DESIGN OF A BIOMASS POWER PLANT

(L-R) Ankush, Amit, Siddhant, Neel, Raghav, Gowtham

Sponsor Name: Dr. Steven Trimble

8th

May, 2014

2

Team Member Page

Each of the members of this group has contributed to and reviewed this final project, and agrees with its

contents.

Signed,

Amit Mehta

Ankush Kumar

Gowtham Ranganathan

Neel Patel

Raghav Kushagra

Siddhant Datta

3

Executive Summary:

The following report is a documentation of the steps and processes followed in completing the graduate

project for Ira A. Fulton School of Engineering, Mechanical Engineering graduate program. The details are

presented to meet the Accreditation Board for Engineering and Technology criteria that demonstrate the ability

of the team to function as successful engineers in a professional environment.

The team worked for preliminary design of a Biomass Power Plant with a capacity of 3MW electrical

power. Fuel in the form of woodchips is burnt in the combustor where the chemical energy is converted into

heat energy. By utilizing this energy high pressure steam is generated and directed to drive the turbine, which

in turn transfers the power to drive the electric generator through a common shaft. The most important project

requirement is to achieve minimum cost of electricity with maximum possible plant efficiency. The federal

rules related to emission and environmental aspects were also taken into consideration.

The detailed preliminary design is presented in section 6 of this report. The electric power output was found

to be 3MW. The cost of electricity was .22 cents/KWh. The plant efficiency was 24 percent. After carrying out

the entire design process the team recommends that in order to make a viable biomass power plant the sponsor

should consider building a higher capacity plant of around 25MW as the component cost would increase only

marginally but the cost of electricity would come down drastically.

The final design is simply a proof that the expected outcome can be achieved. For the purposes of the

project, the capacity of power required to be produced was achieved. However, with further development, we

can achieve a lower cost of electricity than a coal fired power plant. Within the allotted time, the team

accomplished all of the set requirements which were required for the successful design of the Biomass plant

Final Conceptual Design

4

Table of Contents Page No.

ABET Criteria/ Final Report cross reference table 8

1. Introduction 9

1.1 Design Need 9

1.2 Problem Statement 10

1.3 Physics Involved 11

1.4 Project Scope and Limitations 11

1.5 Societal Impact 12

1.6 Applicable Contemporary Engineering Issues 12

1.7 ABET Accreditation and the Assessment Fair 12

1.8 Report Organization 12

1.9 Project Notebook 13

2. Final Design Description 13

2.1 Design Description Overview 13

2.2 Method of Operation 14

2.3 Key Features and Benefits 15

2.4 Cost Results 15

2.5 Requirements/Validation Matrix 16

3. Design Process and Project Planning 17

3.1 Integrated Product Design and Support (IPDS) Process 17

3.2 Project Plan 18

3.2.1 Overview 18

3.2.2 Pre-Concept Design 19

3.2.3 Strategies to Address Key Issues 21

3.2.4 Technical Approach 22

3.2.5 Project Management Approach 23

5

3.2.6 Risk Management Plan 24

3.2.7 Work Breakdown Structure and WBS Dictionary 25

3.2.8 Project Schedules 29

4. Requirements and Constraints 30

4.1 Needs to Requirements 30

4.2 Applicable Standards and Regulations 31

4.3 Validation Methods 32

4.4 Requirements/Validation Matrix 33

5. Conceptual Design 34

5.1 Functional Block Diagram 34

5.2 Research of Prior Art 35

5.3 Conceptual Design Options 38

5.4 Method of Selecting Final Conceptual Design 39

5.5 Final Selection Comparisons and Rationale 42

5.6 Analyses 43

5.7 Prototype Final Conceptual Design 44

6. Preliminary Design 45

6.1 Configuration Block Diagram 45

6.2 Analysis Plan and Results 46

6.3 Failure Modes and Effects Analysis 54

6.4 System Optimization 56

6.5 Trade Studies 59

7. Project Performance 61

8. Project Conclusions 64

9. Recommendations 65

10. Appendices 66

6

List of Figures:

Figure1.1: Boise Cascade LLC- Biomass Plant

Figure1.2: Schematic of a working Biomass plant

Figure 1.3: Basic Physics block diagram

Figure 2.1: Final Preliminary Sketch of Biomass Power Plant

Figure 2.2: Process Flow Diagram

Figure 2.3: Graph of Plant Efficiency vs Plant Cost

Figure 3.1: Integrated Product Development and Support Process

Figure 3.2 Project Plan flow for Biomass Power Plant

Figure 3.3 Schematic of Biomass Direct Combustion System

Figure 3.4: Gantt chart

Figure 5.1: Functional Block Diagram of Biomass power Plant

Figure 5.2: Livestock waste storage facility

Figure 5.3: Woodchips storage facility

Figure 5.4: Bubbling fluidized bed combustion boiler

Figure 5.5: The direct combustion method

Figure 5.6: Co- Firing methods

Figure 5.7: Simple Rankine Cycle

Figure 5.8: Rankine cycle with reheat

Figure 5.9: Rankine cycle with Regeneration

Figure 7.1 Gantt chart showing team progress

Figure 7.2 Labor Chart Biomass Power Plant

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List of Tables:

Table 2.1 Cost and Technical Data

Table 2.2: Features and Benefits

Table 2.3: Performance Results

Table 2.4: Cost Chart

Table 2.5: Requirement Validation Matrix

Table 3.1: Engineering Requirements

Table 3.2: SWOT Analysis table

Table 3.3 Biomass Power Generation Modes

Table 3.4: Possible Risks and its Solution

Table 3.5: Work Breakdown Structure

Table 3.6: Task allocation table

Table 3.6: Task allocation table (cont.)

Table 4.1 House of Quality

Table 4.2 Requirement Matrix

Table 5.1: Criteria for fuel selection

Table 5.2: Criteria for Combustor selection

Table 5.3: Decision Matrix for fuel

Table 5.4: Decision Matrix for Combustion Method

Table 5.5: Decision Matrix for Rankine Cycle

Table 7.1 Labor Chart for Biomass Power Plant

Table 10.1: Emission Standards

Table 10.2: Probability of Failure (Reference)

Table 10.3: Severity of Failure

8

ABET Criteria/ Final Report Cross Reference Table

ABET Requirements Expected level of

Mastery

Achieved

level of

Mastery

Report

Reference

An ability to apply knowledge of mathematics,

science and engineering. Analysis Analysis

Calculation

Appendix I,

II,III, IV

An ability to design and conduct experiments, as

well as analyze and interpret data. Analysis Analysis Sec.6.1, 6.2

An ability to design a system, component or

process to meet desired needs within realistic

constraints such as economic, environmental,

social, political, ethical, health and safety,

manufacturability and sustainability.

Analysis Analysis Sec 5

An ability to function on multi-disciplinary teams. Application Application N/A

An ability to identify, formulate and solve

engineering problems. Analysis Analysis Sec1- Sec9

An understanding of professional and ethical

responsibilities. Application Application Sec6.5

An ability to communicate effectively. Application Application N/A

To broad education necessary to understand the

impact of engineering solutions in a global,

economic, environmental and societal context.

Comprehension Entire

Report

A recognition of the need for and an ability to

engage in life- long learning. Application Sec.9

A knowledge of contemporary issues. Application Analysis N/A

An ability to use the technique, skills and modern

engineering tools necessary for engineering

practice.

Analysis Analysis

Sec3.4, 5,

6,

Appendix

9

1. Introduction

This project report is for the MAE 598 “Energy Systems Engineering” class conducted at Arizona State

University during the time period 01/10/2014 to 05/02/2014. The report addresses the need for a Biomass plant

of 3MWe capacity with minimum cost of electricity.

The deliverables of the project are:

(1) Final Project Report

(2) Final Presentation

(3) Project Notebook.

The sponsor for this project is Dr. Steven Trimble, the instructor for the course. The project team

consists of the following members: Ankush Kumar, Neel Patel, Raghav Kushagra, Amit Mehta, Gowtham

Ranganathan and Siddhant Datta.

This section of the report introduces the project by describing the design need, the resulting project

problem statement, the societal impact, the projects role in ABET accreditation, the organization of the report

and the use of the project notebook.

1.1 Design Need

The design need was a 3MWe capacity Biomass Power Plant with minimum cost of electricity. This

would not only result in increased profit for the customer but the employment and economic growth of the area

would also increase significantly.

The following figure is an example of 11MW electrical power plant at Medford Oregon.

10

Figure1.1: Boise Cascade LLC.- Biomass Plant

1.2 Problem Statement

Non-renewable energy is very expensive and non-ecofriendly. The customer required a profitable

biomass power plant of 3MWe capacity. It was also essential for the customer to ensure that all relevant

statutory laws relating to the environment were abided by during the working of the power plant. The team

concluded therefore that the requirement was to design a 3MWe capacity Biomass power plant with minimum

cost of electricity. Figure 1.2 shows a schematic diagram of a biomass plant.

The problem statement was

Figure1.2: Schematic of a working Biomass plant

(Courtesy: Whole Building Design Guide)

To design a Biomass Power plant that can generate 3MWe electrical power with optimum

efficiency and minimum cost of electricity and which functions within the limits set by relevant

environmental statutory laws. The design will include the final report and the project notebook.

11

1.3 Physics Involved

The basic physics involved in a biomass power plant is explained with the help of block diagram, where

the input is fuel and output is 3MW electrical power. In the Processing Unit, the biomass (wood chips) is

directly burned in a stoker which generates heat and flue gasses. This heat then heats water in the boiler and

converts the water into steam. The steam hits the turbine blades and rotates the turbine shaft. The mechanical

work is then converted into electrical energy by the generator. In many applications, steam is extracted from

the combustor and sent to the air preheater to increase the efficiency of the plant.

Figure 1.3: Basic Physics block diagram

The chemical reaction taking place in the combustor during combustion of wood chips are as follows;

CH1.44O0.66 + 1.03 O2 = 0.72 H2O + CO2 (+Heat)

1.4 Project Scope and Limitation

In this project we are comparing and analyzing all the types of Rankine cycles, Combustion methods

and Biomass fuels which will be best suited for producing the required amount of electrical power with

maximum plant efficiency and minimum cost of electricity. We have tried to accomplish the ABET criteria and

meeting all federal standards related to plant emission and environmental aspects. To prove that we have met

all the requirements, a combustion and thermodynamic analysis will also be done.

There are a few limitations with this project like; the cost of electricity will always be expensive for a

small power output from a biomass plant as compared to coal fired power plant. On the other hand if the

requirement of power would have been more, then the cost of electricity would have been less. The theoretical

data cannot be verified with experimental data, since the time provided for the project was not sufficient.

Processing

Unit Biomass Fuel 3MWe

12

1.5 Social Impact

One of the major challenges facing engineering is developing clean, sustainable source of energy. This

Biomass plant will set an example of generating electricity through renewable sources like wood chips. Since

we know that our planet is very fragile and greenhouse gasses are rising it is our duty to switch from non-

renewable sources to renewable sources.

Biomass plant can create local business, job opportunities and support the rural economy. Many

biomass fuels generate low levels of such atmospheric pollutants as sulphur dioxide and CO2. Modern biomass

combustion systems are highly sophisticated, offering combustion efficiency and emission levels comparable

with the best fossil fuel boilers. The customers will have a healthy environment to stay in.

1.6 Applicable Contemporary Engineering Issues

The Biomass plant has to face many contemporary engineering issues, and they are as follows;

(1). There are a wide number of choices in selecting biomass materials and each present unique utilization

challenges. Heating value, percent volatiles, total ash and moisture content, ash constituents, and particle size

of the fuel are key parameters to consider in designing the plant. The ability to match the biomass fuel

attributes with the unique boiler requirements is a key consideration.

(2). One of the limitations of biomass products such as wood chips is the relatively low, volumetric heating

value or energy density compared to coal or other fuels, requiring a significantly higher volume to be handled

and stored.

(3).Biomass fuels with moisture levels between 20% and 40% create concerns for degradation and spontaneous

combustion.

(4).The fuel cost, location, fuel handling, reliability and dependability, partnerships, and subsidies need to be

addressed for biomass fuels to become a cost-effective, main stream alternative.

1.7 ABET Accreditation and Assessment Fair

The graduate project also serves as a method of evaluating the mechanical engineering program at

Arizona State University. The ABET Criteria/ Final Report Cross Reference Table is provided to help ABET

project assessors find objective evidence in the final report for meeting each of the ABET criteria.

1.8 Report Organization

The report is divided into 9 sections. Section 1 discusses the societal need, the project problem

statement and the project scope. Section 2 presents the solution to the problem statement, i.e., the final

design description in the form of a matrix. The next few sections describe the design/development

process, i.e., Design Process and Project Plan, Requirements, Conceptual Design and Preliminary

Design. Section 7 discusses the team‟s project effectiveness. Section 8 covers the project conclusions

and Section 9 provides go-forward recommendations. Following Section 9 are the Appendices.

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1.9 Project Notebook

The team organizes all its work into a Team Project Notebook that is used throughout the

project to document the work. The notebook contains detailed descriptions of all trade studies,

analyses, tests, and team decisions. The final report is written as a comprehensive, stand-alone

document. However, it refers to the notebook as needed to direct the reader to more detailed

information regarding the design.

2. Final Design Description

This section describes the final design that meets the customer needs. The remaining part of this report

explains the design process that resulted in this final preliminary design.

2.1 Design Description Overview

The Figure 2.1 shows the final preliminary design & components of the biomass power plant

developing power of 3MW. Steam enters in the turbine at 800 Psi pressure and 840 F. To achieve these

conditions biomass fuel (Wood chips with 20% MC) are burnt in combustor and develop gases at 1800 F. The

hot flue gases are passed through boiler to generate steam.

To remove the moisture content wood chips are processed in drier before sending to combustor. As

shown in the figure flue gases at 350 F from combustor are allowed to go through drier before going to stack

and then to atmosphere. Overall efficiency of the plant is 27.89%.

14

Figure 2.1: Final Preliminary Sketch of Biomass Power Plant

Following table shows the cost and technical data for the final Preliminary design.

Table 2.1 Cost and Technical Data

Technical

Specification

Moisture

Content of Fuel

(Wet Basis)

Fuel

consumption

Rate (lbs/hr)

Plant Overall

Efficiency (%)

Plant Cost

(USD)

P=800 Psi

T= 840 F

20% 6420.7 27.89 17916650.00

2.2 Method of Operation

The process of power generation involves converting chemical energy of fuel into mechanical energy

by burning wood chips into the combustor and utilizing the heat for steam generation. The generated steam is

utilized for power generation by using Rankine thermodynamic cycle. A process flow diagram is shown in

Figure 2.2.

Figure 2.2: Process Flow Diagram

(Start)

Wood chips

store yard.

In this section fuel is

processed in Drier

for removal of

moisture content.

In this section wood

chips are burned (in

combustor) and

heat energy

liberated is used for

steam generation.

Flue gases from the

combustor are

directed to drier and

then to stack.

(Stop)

In this section steam

is directed to

turbine for power

generation.

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2.3 Key Features and Benefits

The following table shows the key features and benefits of the biomass plant designed by the team.

Table 2.2: Features and Benefits

Features Benefits

Installation of Drier Remove moisture content from feed stock and

increase the efficiency and also reduce the plant cost.

Emission Control (ESP) Precipitate carbon particles

2.4 Cost Results

This section consists of a table and graph showing the cost versus efficiency data for the plant based on

different component combinations.

Table 2.4: Cost Chart

Cost Installation

S.No Inlet

Conditions Dryer Combustor Boiler

Turbine and

Generator set Total

Plant

Efficiency

1 P=840 psi,

T= 800 F $200,000 $4,555,710 $6,074,280 $7,086,660 $17,916,650 0.28

2 P=640 psi,

T=600 F $217,908 $6,823,005 $5,264,376 $6,479,232 $18,784,521 0.21

3 P=440 psi,

T= 400 F $225,433 $7,330,581 $4,859,424 $6,276,756 $18,692,194 0.18

$17,000,000.00

$18,000,000.00

$19,000,000.00

0.17 0.19 0.21 0.23 0.25 0.27 0.29

Pla

nt

Cost

, ($

)

Efficiency,

Plant efficiency vs Plant Cost

16

Figure 2.4: Graph of Plant Efficiency vs Plant Cost

2.5 Requirement Validation Matrix

We used the modified Quality Function Deployment (QFD) to convert the voice of customer into the

Technical requirements. The detail table and the requirements are specified in section 4.1.

Requirement matrix consist of 3 columns one specifying the requirements, next one specifying the

conceptual design (chosen concept values) and the last column has the Preliminary design values which

represent the calculated values which are verified for the chosen concept from Conceptual Design. The

importance of Requirement/Validation matrix is to make sure that the requirement i.e. customer needs are

achieved at each stage of the designing process.

Based on the QFD table shown above, the team decided to use the following requirements to design the

Biomass Power Plant. The below table gives the requirements along with the details of how it will be validated

and what is the status of the requirement, i.e. whether the requirement is met or not.

Table 2.5: Requirement Validation Matrix

S.No. Requirement Method of

Validation

Validation Result

1 3 MWe capacity Thermodynamic

Model

Able to produce

3MWe

2 Cost of Electricity should be less than

$0.25/kWh

Analysis – Hand

Calculation

Able to achieve

$0.22/kWh

3 Exhaust Stack Temperature should be

around 325ᵒF to 350ᵒF

Thermodynamic

Model

Have 350F

temperature at Stack

4 Emissions within the limits mentioned in

appendix(a)

Analysis – Similarity

5

Moisture Content of the air at intake of

combustor should be less than 10-30%.

(to have better efficiency from combustion

process)

Analysis – Sensitivity Moisture content of

air is calculated to be

20%

6 Feedstock must be able to be stored for at

least 5 days at any given time.

Analysis – Hand

Calculation

Storage unit volume

should be able to hold

atleast 770400 lbs of

fuel (fuel req. for 5

days)

7 Proper Disposal of Waste water and ashes

from combustion

Analysis – Similarity Has to be met while

building the plant.

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3. Design Process and Project Planning

The team followed the Integrated Product Development and Support (IPDS) design process to design the 3

MWe Biomass Power Plant. The project is planned to optimize by using the sensitivity study of various

variables with respect to Cost of Electricity (COE) and uses it to fix the appropriate values of each variable to

optimize the COE. The Section 7 includes the detail presentation of the team‟s actual project conduct in terms

of schedules and budgets.

3.1. IPDS Design Process

The IPDS Design Process has 6 phases by which the customer needs are converted into deliverable

products with support and improvement. The process flow of IPDS is shown below.

Figure 3.1: Integrated Product Development and Support Process

The six phases of IPDS process is explained briefly below.

1. It starts with collecting customer needs from the customers, based on the customer needs the

team develops a Pre-Concept design to get the proposal approved from the management.

2. Once the project is approved the team begins with developing various Concept to meet the

requirements of the customer needs.

3. From which one best concept is selected and carried forward to the Preliminary Design where

the components are selected for the Design.

4. In the next step the team does Detailed Designing to fix the component dimensions to match the

selected design parameters.

5. After which the prototype is developed to do testing and quality check.

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6. In next step, the product is delivered and the team works continuously to provide support and

improvement till the committed period or the life of product.

For this Class Project, our team goes only through Preliminary Design i.e. till third phase of IPDS

process.

3.2 Project Plan

This section explains how the team has planned to do the Biomass Power Plant Project.

3.2.1 Overview

The team was formed based upon the interest of the individual to work for the given problem

statement by the Professor. In the end there were 6 individuals who were interested to work for Biomass

Power Plant. After which the each individual committed to work for Biomass Project with single motive

which is best for the team at each and every stage of the progress.

The below figure shows the flow of Project Plan based on which the team planned to work on the

project.

Figure 3.2 Project Plan flow for Biomass Power Plant

The team started would start with customer needs to develop the Pre-Concept Design based on which

the necessary tasks for the project have to be determined. With the task description the team can figure out the

time, labor and money needs for the project to be completed. After which the task will be allotted and also

how the team approached the project technically. Then the team finalizes the Project plan which will be used

to develop the project.

SWOT Analysis

Task Description Strategy

Customer

Needs

Technical

Requirements Pre-concept

Design

Estimating Time, Labor

Resources, Money

Resources

Defining Roles and

responsibilities

Summarizing Technical

and Management

approach

Finalizing

Project Plan

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3.2.2 Pre-Concept Design

The Team began to prepare the Pre-Concept design with a set of Technical Requirements which are

derived from the problem statement obtained from the customers based upon their needs. The list of 3 basic

engineering requirements used to develop pre-concept design is given in the below table.

Table 3.1: Engineering Requirements

3MWe Electricity using Bio-waste

Emission meeting state and federal laws

Cost of electricity lesser than $0.25/kWh

Based on the pre-requirements shown above the team developed Biomass power plant with realistic

but non-optimized pre-concept design. The pre-concept design developed by the team is shown in the below

figure.

Figure 3.3 Schematic of Biomass Direct Combustion System

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The biomass is feed into the boiler which generates steam which is then used to run the turbine

connected to the generator to produce electricity. The exhaust gas from boiler is feed to the stack via Heat

Exchanger. The steam from turbine is condensed and pump to heat exchanger to get preheated in it by the

exhaust gas and if feed to the boiler.

The pre-concept design explained above will be discarded when the conceptual design is started. That

is, the team will create a new and more complete set of requirements and a structured conceptual process will

be followed to make sure the entire design space is explored.

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3.2.3 Strategies to Address key success

In order to tackle any issues the team will face during the project phases a SWOT analysis is

developed in which the list of strength, weakness, opportunities and threat which the team will have during

the project phase is listed below in the table.

Table 3.2: SWOT Analysis table

S.No. Item Description S.No. Item Description

Strength Weakness

1 MATLAB

Programming skills is a

big advantage. Use

computer to perform big

calculations in a short

time.

1 New to the

field

The Project execution

and planning may be

delayed. Less experience

may lead to wrong

decisions.

2 CATIA V5 CAD modelling of the

power plant. 2 Documentation

Preparing prefect

documentation is difficult

3

Conceptual

Design

Experience

Better understanding of

Conceptual design and

Concept generation

techniques

3 Time

management

Poor time management

may lead to heavy

workloads towards the

end of the project.

4 Project

Experience

Aide in the organization

of the project

5 Thermal

Analysis

Required to calculate the

properties of steam as

well as aide in the

thermal analysis of the

plant.

Opportunities Threat

1 Biomass

plant visit

A visit to an established

plant can give the

invaluable experience.

1 Failure to meet

plan

Schedules should be

followed, but due to

unavoidable and

sometimes lethargic the

plans might not be met.

2

Relations

with

suppliers

With the help of

Professor who has many

industrial contacts the

suppliers are reachable

and maintaining a good

relationship is important

to obtain details.

2 Limited

resources

Allocation must be

optimized; otherwise the

overall result may be

affected.

3

Industrial

Project

Experience

Team members

experience in the field

will help in the project

building.

3 Unforeseen

Circumstances

Extraordinary

circumstances may lead

to a delay in the schedule

tasks completion

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3.2.4 Technical Approach

To design and develop a Biomass plant, various factors need to be answered and considered. A

suitable approach is displayed as follows;

1. Provide a detailed scope of work for the plant:

1.1 Feasibility studies- Includes determination of various components in the plant.

1.2 Identifying issues- Project proposal will only succeed or fail on the public perception of

its environmental effects.

1.3 Site selection- A systematic approach is needed to ensure that the chosen site meets

the environmental, civil and engineering requirements.

1.4 Planning applications & Enquires- This includes applications of permission from the

government and the county for a bunch of laws.

1.5 Project design and summary.

1.6 Conceptual design.

1.7 Plant design.

2. Comparison of Biomass power generation modes:

The below table shows the comparison of biomass power generation modes.

Table 3.3 Biomass Power Generation Modes

MODE COMBUSTION GASIFICATION COMBUSTION

MIXED

BURNING

GASIFICATION MIXED

BURNING Technological Characteristic

Biomass

burned directly in

boiler to produce

steam to

generate

electricity.

Biomass

gasified and then fuel gas

burned in gas

turbine or

engine.

Biomass

mixed with coal

and burned in

boiler.

Biomass

gasified first and then

fuel gas burned

with coal in

boiler. Advantage Large scale,

simple biomass

pretreatment,

reliable

equipment

and low running

cost.

Low

emission pollution, high

efficiency at

small scale, low

investment.

Simple

and convenient

operation.

Universal application, low

impact on

original coal

fired system,

economic

benefit. Disadvantage High

emission pollution, low

efficiency at

small scale,

large investment.

Complex equipment,

high

maintenance

cost.

Strict

biomass quality

and

pretreatment,

some impact

on original

system.

Complex management,

erosion problem.

Application Condition

Large scale

power generation.

Medium

and small system.

Suitable

for timber biomass

and special

boiler.

Power

generation for mass

biomass.

23

3. Process flow chart.

4. Utility requirements like Natural Gas Fuel Supply, Water Supply, Waste Water Treatment/

Disposal, Solid Disposal.

5. Environmental aspects related to air and solid emission, dust, noise, storm water, fuel delivery traffic. 3.2.5 Management Approach

This section explains how the team has planned to meet the project in term of management aspects

right from preparing project plan to design a preliminary design of the Biomass power plant. Main aim of the

project is to present a Preliminary Design, Conceptual Design of a Biomass Power Plant that can generate

3MW of power without producing any hazardous materials into the environment and meeting all other

requirements of the project.

Management Functions

- The base plan for the plan is to focus on weekly task while keeping in mind the final deliverables

- The Project Plan is organized in such a way that each member has equal number of work allotted to

them and allowances are given for any unforeseen events.

- The Plan is in controlled manner without giving any excess work to anyone.

Usage of Project Plan

- Project Plan is just a reference material which is to be followed to achieve the goal, but when the

project proceeds, the plan will be changed according for the development and issues without influence

the final goal.

Meetings

- Meetings have been planned for twice a week on Thursday and Saturday in Noble Library

- The minutes of the meeting are written down for future references

- The meeting agenda is pre-planned and time for the meeting is changed according to the agendas

- A Common drive is been created to share each member work which can be view by all other

members, which helps in saving time during meeting.

- Focus of the meeting is to discuss any changes in anybody work and compiling the deliverable and

also

on priority of things to be focus and how to change the approach as need.

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3.2.6 Risk Management

The Risk management is address in the tabulation below. When the team comes across any risk the

team meeting and discuss on how to get over the issue. Some time is allocated for address this issue. The

below table shows what are the risk team might face during the project phase and what are the possible

solution which can be followed to tackle the risk.

Table 3.4: Possible Risks and its Solution

Priority Levels

A High

B Medium

C Low

D Not a priority

Risk Management

Sr.

No.

Priorit

y

Risk Solution

1

A

Environmental

The plant should meet the

regulations set by the government and local authorities. 2 A Financial Monetary risks due to change in

profits.

3

A

Feedstock

Supply

Shut down threat due to low

feedstock supply.

4

A

Legal

Emission Rules and Regulations

pose a major threat. 5 A Labor Labor Unions, Strikes.

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3.2.7 Work Breakdown Structure

This section describes how the team has scheduled its necessary task based on the labor resource and

time requirement of the completion of the project. The task are set equally to each person based upon their

interest and their availability at specific time.

Work Breakdown Structure is the overview of the project schedule which describes how many hours of

work will be put in per hour for the completion of the project. The below diagram shows

Table 3.5: Work Breakdown Structure

H

o

u

r

s

p

e

r

w

e

e

k

Semester Weeks 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Research 30 1

0

Project Plan 2

0

1

0

System Requirements 2

0

Concept Generation 1

5

Trade Studies 1

5

Final Conceptual

Design

3

0

Budgetary studies 1

5

Thermodynamic Model 1

5

1

5

Cost Model 1

5

State Point Diagrams 1

5

Hand Drawings 1

5

Bill of Materials 1

5

Solid Works Model 2

0

DFMEA 1

5

Sensitivity Study 1

5

Final Design

Description

3

0

Final Report 3

0

Final Presentation 3

0

26

Assuming X hours for research, we are calculating the working hours for the rest based on it.

Research – X Project Plan – X

Requirements – 2X Concept Generation –2X

Final Conceptual Draft - 2X

Hand drawings – X

Creating Bill of Materials - .75X

State Point Diagrams - .5X

Cost Model – X

Final Drafting – 2X

Collecting Budgetary Info - X

Trade Studies - .5X

Cost of Electricity – .5X

Thermo model - .75X

Solid Works model - .5X

DFMEA - .5X

Sensitivity Study – X

Risk Management – X

Documentation – 4X

Miscellaneous – 2X

Presentation – 2X

Total Hours - 27X

Project Deliverables

Project Plan

Conceptual Design Draft Final Design Draft Presentation

Total No. of Hours needed = 27X

No. of Hours committed per week = 6 hours

Total no. of weeks = 10

No. of Members in team = 6

Total No. of working hours by the Team = 360 hours

27

No. of working hours need per week = 360/10 =36 hours

No. of working hour per person per week = 36/6 = 6hours

From the above shown calculation it is determined that each member of team would be working for 6

hours a week to finish the project on planned day which is when the project is due.

Based on this we developed an approximate schedule of the number of how each member will be

working on to complete the task necessary to complete. The allocation of task for specific member in the team

is given in the below table.

Table 3.6: Task allocation table

Work Am A G N R S Am A G N R S Am A G N R S Am A G N R S

Final

Drafting of

Project Plan

2 3 2 3 3 6

Requirements 4 2 4 2 3 2 6 2 1

Concept

Generation 3 4 4 4 6 1 2 3 2 2 3

Sketches 1 3 2

Trade Studies 5 4 2 4 4 3 1 2 4 3 3 3

Final

Conceptual

Drafting

3 4 2 1 3 3

Collecting

Budgetary

info

2 2

Total

Hours/person 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

Hours/week 36 36 36 36

Legends

Am Amit

A Ankush

G Gowtham

N Neel

R Raghav

S Siddhant

28

Table 3.6: Task allocation table (cont.)

As shown in the above table, it is estimated the completion of project will take up to 19th

week. This

matches to the due date of the project. In case if the team couldn‟t meet the schedule the team member has

agreed upon to work extra hours to complete the project on time.

Work Am A G N R S Am A G N R S Am A G N R S Am A G N R S

Thermo-

model 4 3 2

COE model 5 2 3

Cost of

Electricity(Op

timization)

3 3 4 2 2

State Pt

Diagrams 3 3 2 2

Hand

Drawings 4 4

Creating Bill

of Materials 4 4

Solid works

model 2 2

DFMEA 4 3 3

Sensitivity

Study 4 4 3 1

Risk analysis 3 4 2

Final Drafting 2 2 4 5 2 1 2

Final Report 4 6 5 6 4 6

Total

hours/person 5 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

Total

hours/week 35 36 36 36

29

Gantt chart

The below figure show the gnat chart for the Biomass power plant project.

Figure 3.3: Gantt Chart

We planned the project plan in such a way that the project will be completed by May 6th

in 13 weeks

and working for total of 360 hours throughout the semester. And each person will be working for around

5hour per week.

3.2.8 Project Success Factors

The project success factors are

1) Detailed Planning.

2) Knowledgeable and experienced team members.

3) Good communication within the team.

4) Careful Risk Management.

30

4. Requirements and Constraints

Requirements are the entities that describe the specification of the design problem which are derived

from the customer needs. A design problem is usually based upon the needs of the customer life. The design

problem is generally formulated with additional requirements by the designer which includes customer needs

and things that are required to fulfil the customer requirements. The problem is generally specified by a set of

design goals and requirements.

Constrains are generally requirements which have limits or restriction values given to them. For

example: the cost should not exceed $2 million or downtime should not exceed 10 days in a year. The

environmental laws are also consider as constrains which generally have to be under the specified limit.

Requirement/Validation Matrix

Requirement matrix consist of 3 columns one specifying the requirements, next one specifying the

conceptual design (chosen concept values) and the last column has the Preliminary design values which

represent the calculated values which are verified for the chosen concept from Conceptual Design. The

importance of Requirement/Validation matrix is to make sure that the requirement i.e. customer needs are

achieved at each stage of the designing process.

In section 4.4, a modified form of Requirement Validation Matrix is shown, which shows the

requirements in the first column, how it will be validated by the team and the result of validation status in the

following columns.

4.1 Needs to Requirements

There are various ways to convert the Voice of Customers into the technical requirements one of the

way is to use House of Quality table (Quality Function Deployment(QFD)). QFD is a tool used by many

industries to convert their customer needs into the Technical requirements which are then used by the Designers

to choose a Concept from the number of available concepts. QFD also gives the relationship between various

customer needs which helps in understanding design process better.

The team has used a modified form of House of quality to derive the Technical requirements from the

Customer Needs. The Customer Needs were derived from the problem statement, which are then converted to

Technical requirements. The below table shows customer needs and its equivalent one or two technical

requirements along with their strength of relationship which are being weighted as 1, 3 or 9. In which, 1 being

very poor, 3 being weak and 9 being strong relationship.

31

In below table, the first column has the set of Customer requirements and the top row specifies its

corresponding Technical Requirements. In Biomass Power Plant, problem statement „Cheap Electricity‟ is the

basis, so it is a customer need and its equivalent technical requirements is „Cost not to exceed $.50kW/hr‟ and

their relationship is strong which is indicated by 9 in the cell where they both intersect. Similarly all other

customer needs and their corresponding technical requirements are shown in below table.

Table 4.1 House of Quality 1 – Poor Relation

3 – Weak Relation

9 – Strong relations

Customer needs/ Technical

Requirements

3 M

We

capac

ity

Cost

not

to

exce

ed

$.5

0kW

/hr

Volu

me

of

the

Chopper

Cap

acit

y s

hould

be

4.5

to 6

Tons

Dow

nti

me

should

n‟t

be

more

than

120hr/

yr

Dis

posa

l of

Was

te

wat

er a

nd a

shes

More

th

an

10%

mois

ture

conte

nt

in f

uel

Aro

und 3

50ᵒC

Exhau

st

Sta

ck T

emper

ature

Cheap Electricity 3 9 1 1 1 1 1

Less environmental Pollution 1 1 1 1 9 1 1

Use waste woods/weeds 1 1 1 1 1 9 1

Less odor 1 1 1 1 9 3 1

Continuous supply of electricity 1 1 9 9 9 9

Produce electricity for a specified

area 9 3 1 3 1 1 1

4.2 Applicable Standards and Regulations

The major standards and regulation of the given problem i.e. for a power generation from a Bio-mass

Power Plant are identified based on the environmental requirements and the process requirements to produce

3MW of electricity from the Biomass Plant from the given fuel. Some of the standards and regulation for

Biomass are given below:-

Exhaust emission from the power plant should follow NAAQS1

The odor from the plant should not be more than that mentioned in the regulations.

The ash content should be less than that mentioned in the regulations.

1 National Ambient Air Quality Standards (NAAQS) see appendix for details

32

4.3 Validation Methods

The requirements need to be validated to meet the customer needs by at least one of the following

validation process

1. Analysis – Similarity

In this method, the process/component used to develop the Power Plant is compared to one of

existing/existed plant to validate whether the plant meets certain requirements.

2. Analysis – Sensitivity

In this method, a graph is drawn to study how a variable will be varied with respect to other

variable, which helps in understanding the behavior of the variables.

3. Analysis – Computational

In this method, a computational model is developed in one of software packages and it is

analyzed to check whether the design meets the requirements.

4. Prototype Testing

In this method, the team builds a smaller version of the product/component to test it under the

real time condition to check whether the system will produce the required outcome.

5. Analysis – Hand Calculation

This is most generally used method, wherein the team does the thermodynamic calculation by

assuming certain assumptions and does the calculation to see whether the assumption meet the required

results, if not the assumptions are changed and calculations are re-done till the required results are

achieved.

33

4.4 Requirements/Validation Matrix

Based on the QFD table shown above, the team decided to use the following requirements to design the

Biomass Power Plant. The below table gives the requirements along with the details of how it will be validated

and what is the status of the requirement, i.e. whether the requirement is met or not.

Table 4.2 Requirement Matrix

S.No. Requirement Method of

Validation

Validation Result

1 3 MWe capacity Thermodynamic

Model

Able to produce

3MWe

2 Cost of Electricity should be less than

$0.25/kWh

Analysis – Hand

Calculation

Able to achieve

$0.22/kWh

3 Exhaust Stack Temperature should be

around 325ᵒF to 350ᵒF

Thermodynamic

Model

Have 350F

temperature at Stack

4 Emissions within the limits mentioned in

appendix(a)

Analysis – Similarity

5

Moisture Content of the air at intake of

combustor should be less than 10-30%.

(to have better efficiency from combustion

process)

Analysis – Sensitivity Moisture content of

air is calculated to be

20%

6 Feedstock must be able to be stored for at

least 5 days at any given time.

Analysis – Hand

Calculation

Storage unit volume

should be able to hold

atleast 770400 lbs of

fuel (fuel req. for 5

days)

7 Proper Disposal of Waste water and ashes

from combustion

Analysis – Similarity Has to be met while

building the plant.

34

5. Conceptual Design

Biomass energy is abundant and renewable. It has developed into an alternative source of energy and

reduced our dependency on conventional fossil fuels. However, biomass energy is also quite expensive and

inefficient compared to conventional fossil fuels. It was hense concluded that to build a viable biomass power

plant, topmost priority had to be given to reduced cost of electricity (COE) and emissions, and increased

efficiency. The major factors affecting the COE, efficiency and efficiency of a power plant are

Type of fuel

How the energy of fuel is converted to electrical energy

In this section, these two things will be analysed and based on efficiency, emissions and COE, optimum

comceptual design shall be presented.

5.1 Functional Block Diagram

Figure 5.1: Functional Block Diagram of Biomass Power Plant

As shown in Fig 5.1 the basic functions of the power plant are as follows

1) Delivery of appropriate fuel to the power plant.

2) Grinding and drying of fuel to enable direct delivery to energy conversion system

3) Converting chemical energy of fuel to heat energy with the help of a combustor and heat

exchanger.

4) Converting the available heat energy to electrical energy with a turbine generator set.

5) Proper disposal of byproducts of energy conversion process based on requirements

6) Optimum waste heat rejection to ensure high efficiency.

Delivery of fuel Storage and

preparation of fuel for energy conversion

Conversion of chemical energy of fuel to heat energy

Conversion of heat energy to electrical

energy

Waste Energy

Rejection

Proper disposal of

byproducts

35

5.2 Research and prior art

The factors which critically affect the efficiency, emissions and cost of a biomass power plant are

Fuel

Chemical to heat energy conversion

Thermodynamic Cycle

5.2.1 Fuel

Most of the existing power plants all use solid biomass fuel in the form of wood chips to heat water to

generate steam; however some also use agricultural waste products like fruit pits and corn cobs, or landfill gas

like methane and alcohol fuels like ethanol. The steam is then use to rotate a turbine and generator to generate

electricity.

5.2.2 Heat Energy eneration

Most power plants use direct combustion where biomass is burnt directly in boiler to produce steam.

This is a fairly mature technology with low running cost and simple biomass pretreatment. Another way to

extract chemical energy of biomass is gasification combustion where solid biomass first breaks down to form a

flammable gas which can then be burnt to generate heat. However gasification requires complex equipment and

high maintenance cost.

Other methods include mixed burning where biomass is mixed with coal and burnt in a boiler. This

method requires strict biomass pretreatment and quality which would increase cost. Other ways include

Biomass liquefaction via pyrolysis which is similar to gasification, or biogas anaerobic digestion where biomass

is first converted to biogas which is then burnt to generate heat. When compared to direct combustion all these

methods have significant disadvantages in terms of maintenance and cost. After exploring all the options, direct

combustion was selected based on the advantages it offers. The fuels available for direct combustion are wood

chips, landscape waste and livestock waste.

Figure 5.2: Livestock waste storage facility Figure 5.3: Woodchips storage facility

(Courtesy: www.njaes.rugers.edu) (Courtesy: www.dreamstime.com)

36

5.2.3 Combustion:

The two most commonly used methods for biomass firing are stoker boilers and fluidized bed boilers.

Either of these can be fueled entirely by biomass fuel or co-fired with a combination of biomass and coal.

Stoker boilers employ direct fire combustion of solid fuels with excess air, producing hot flue gases which then

produce steam in the heat exchange section of the boiler. Fluidized bed boilers are the most recent type of boiler

developed for solid fuel combustion.

The primary driving force for development of fluidized bed combustion is reduced sulphur and nitrogen

dioxide emissions. In this method fuel is burnt in a bed of hot inert, or incombustible, particles suspended by an

upward flow of combustion air that is injected from the bottom of the combustor to keep the bed in a floating or

fluidized state. The scrubbing action of the bed material on the fuel enhances the combustion process by

stripping away the carbon dioxide and solids residue that normally forms around the fuel particles.

Note: The Co-Firing method has lately become popular in the coal based thermal power plants; thanks to

the easy availability of biomass(refer to appendix b). The cost of the fuel per kWe has reduced significantly in

europe and north american companies by using the co-firing method. However, this method can be emploed

only in large scale power plant (>100MWe).

Figure 5.4: Bubbling Fluidized Bed Figure 5.5: The Direct Combustion Method

Combustion boiler

(Courtesy : www.energy-enviro.fi) (Courtesy : www.busytrade.com)

37

(a) (b)

Figure 5.6: Co-Firing method. The part (a) shows the mixture of coal and wood is fed to the pulverizer

via a conveyor belt and the part (b) shows how the fuel mixture is fed to the boiler.

(Courtesy: www.barr.com)

5.2.4 Thermodynamic Cycle

Rankine cycle consist of following processes.

Process 1-2: Isentropic Compression in Pump

This process is called isentropic compression process where saturated water is pumped

isentropically to state 2 and enter to the boiler. A centrifugal pump is generally installed for this purpose.

Process 2-3: Constant Pressure Heat addition in a Boiler

Water in boiler at state 2 is heated till superheated region to state 3. This process take place at

constant pressure thus called as isobaric heat addition. In this section, combustion gases reject the heat

which is utilized to raise the water temperature and convert it into superheated steam.

Process 3-4: Isentropic Expansion in Turbine

In this stage superheated vapor enters in the turbine and expand isentropically (enthalpy drop)

and produce work. The work developed by the turbine is used to drive the electric generator through a

common shaft by which they are connected.

Process 4-1: Constant Pressure Heat Rejection

This is a constant pressure process wherein heat is rejected to cooling medium. A condenser is

installed for this purpose. Steam from the turbine outlet enter the condenser and cooled to saturated

liquid at constant pressure to state 1.

38

So far we have explained about the ideal Rankine cycle. Based upon the heat available at temperature

(1800 F) from combustion of biomass fuel, we have decided to use Rankine cycle with reheat.

Figure 5.7: Simple Rankine Cycle

(Courtesy: www.ou.edu)

5.3 Conceptual Design Options

Based on the research and prior art, the following options were analyzed, and then narrowed down based

on requirements.

5.3.1 Fuel:

Since direct combustion was the optimum energy conversion method, landfill gas like methane and

alcohol fuels like ethanol were rejected. The team narrowed down the viable solid fuel options to

1) Wood chips

2) Livestock waste

3) Landscape waste

5.3.2 Combustion:

Since direct combustion was selected as the method of chemical to heat energy conversion. The

available options are:

1) Water tube boilers,

2) Fluidized bed combustion,

3) Stoker fired boilers.

4) Co- firing with coal

39

5.3.3 Thermodynamic Cycles:

Typically following are the Rankine cycles which are used.

1) Ideal Rankine cycle

2) Rankine Cycle with Reheat

3) Rankine cycle with regeneration

5.4 Method of selecting final conceptual design

A decision matrix evaluates and prioritizes the list of available options. The design team first established

a list of weighted criteria and then evaluated each option against these criterias to select the optimum design

option.

Criteria like cost, emissions, efficiency, etc which affect the overall performace of the plant have been

assigned an appropriate weightage on a scale of 0-10 with 10 assigned to most critical criteria based on

requirements.

Next all available options have been assigned a rank between 0-10 with 10 being the highest against

each criteria based on research and brainstorming.

Finally a Weighted value = ∑ (Weightage x Ranking) has been calculated for each design option to

select the best option.

5.4.1 Fuel

Since the most important requirement of the project were minimum cost, high efficiency and low

emissions, the team decided to establish the following criteria for fuel selection.

Table 5.1: Criteria for Fuel Selection

Criteria Weight Rationale

Cost 10 Top priority was cost so

maximum weight was given to it

Emissions 9

Emissions was one of the

requirement so 9 points have

been given

Availability 8

Availability is to also important

to ensure smooth functioning of

the plant

Calorific Value 9 Calourific value directly affects

the efficiency.

40

The calorific value, cost and fuel emission information of each available fuel needs to be known to give

an appropriate rank and make a rational comparison which shall be done in section 5.5 of the project report.

5.4.2 Combustion Method

Since direct firing was selected, the team established the following criteria to select the best

boiler/combustor to achieve minimum cost and emissions.

Table 5.2: Criteria for Combustor Selection

Criteria Weight Rationale

Cost 10 The plant is to be designed for

lowest cost hence the cost is

weighted at 10.

Emissions 10 Strict Emissions control, less

emission are desirable

Maintenance 5 A secondary priority hence

the low weighting

Operability 6 A secondary priority hence

the low weighting

5.4.3 Thermodynamic Cycle

As described in section 5.2 Rankine cycle is used as thermodynamic cycle for power generation by

steam. Generally, three types of Rankine cycles are used for power generation which are listed as below.

Ideal Rankine Cycle

Rankine cycle with reheat

Rankine cycle with regeneration

Ideal Rankine cycle consist of 4 different processes which are already explained in section 5.2.

5.4.3.1 Rankine cycle with Reheat:

In this cycle, steam is reheated but at lower pressure. Two turbines, High Pressure and Low Pressure are

installed for reheating system. Steam at high pressure is expanded in HP turbine as shown in figure from state 3

to state 4.

41

Now, steam at state 4 is directed to boiler for reheating which resulted out steam at higher temperature

and i.e. state 5. Now steam is expanded in LP turbine to state 6. Advantage of reheat is that, efficiency of the

plant is increased because we are using the same amount of heat for producing more work as without reheat.

Further, if we look at the turbine outlet which is nothing but at state 6 steam is saturated and have good quality

i.e. dryness fraction is 1.

Impact of good quality of steam is good working life of turbine blades. But this system leads to increase

in cost because for reheating we have to install super-heaters which are having expensive MOC (material of

construction). Because of their exotic metallurgy and high temperature operating conditions, cost will be

increased to a significant amount. So, weighted matrix study need to be carried out for the selection or rejection

of this system.

Figure 5.8 Rankine Cycle with Reheat

(Courtesy: www.ou.edu)

42

5.3.2 Rankine cycle with regeneration:

Efforts are always put to get maximum efficiency. Rankine cycle with regeneration is used to get higher

efficiency. In this Rankine cycle system, turbine is split into two stages, one is high pressure and another is low

pressure stage. Steam from the high pressure turbine is bleed out and supplied to Feed Water Heater. As shown

in the figure steam at state is 5 is sent out and supplied to Feed water heater at state 7 where it get mixed with

water from condenser. After mixing the temperature of the Feed water is raised which leads to increase in plant

efficiency.

Figure 5.9 Rankine Cycle with Regeneration (courtesy ecourses at www.ou.edu)

All these thermodynamic cycles have some merits and demerits. A weighted matrix study has been

carried out for the selection Rankine cycle for our project. After carrying this study simple Rankine cycle has

the highest ranking to meet our project requirements.

5.5 Decision Matrix for Fuel

Parameter with high importance, cost of fuel in this case, has been assigned maximum weightage of 10

at a scale of 0-10 e.g. Efficiency and emissions also important factors but relatively lesser important than cost

and are a weightage of 9 keeping into consideration the project requirements.

Hence wood chips turns out to be the best options among the available choice of fuels for the biomass

plant. Wood chips can be obtained for use as fuel without involving high costs of transportation due to its

reasonable availability. Cost for this fuel is also reasonable and emissions are below the government established

emission standards.

43

Table 5.3 Decision Matrix for Fuel

5.6 Decision Matrix for Combustion method

The below is the decision matrix for combustion method selection.

Table 5.4 Decision Matrix for Combustion Method

44

5.7 Decision Matrix For Rankine Cycle

Criteria for weighted matrix for selection of Rankine cycle:

To reach for a decision and selection of the Rankine cycle, a weighted matrix study has been carried out.

In this matrix three (3) Rankine cycles are rated and weighted. Each Rankine cycle system has merits and

demerits and must be fit to our project requirements. Low COE and high efficiency are the main requirements

and is the basic milestone for this study.

Weighted value= Weightage X Rating

Rankine cycle with maximum weightage has been selected for further analysis. Here after study,

Rankine cycle without reheat has maximum weightage which is 271 and will be part of further analysis and

preliminary design.

Matrix with various weightage and rating for Rankine cycles is shown as below.

Table 5.5 Decision Matrix for Rankine Cycle

45

6. Preliminary Design

6.1 Configuration Block Diagram

Configuration block diagram shows the working functional model with each function being

replaced by the one of the component with state point at critical places. Configuration block diagram of

Biomass Power Plant is shown below.

Figure 6.1: Configuration Block Diagram

46

6.2 Analysis Plan and Results

We followed the following flow chart for analysis plan to design the design point with the main

objective to minimize the COE (cost of electricity) with maximum efficiency. From the design points we

optimized the COE from the sensitivity study of we did on various design variables.

Figure 6.2: Analysis Plan

We did thermodynamic analysis for three different inlet conditions to figure out which condition is

more efficient. The below table shows the three inlet conditions with their efficiency.

For 3 different Turbine

Inlet conditions

800 psi, 840F

600 psi, 640F

400 psi, 440F

Thermodynamic Efficiency &

Steam mass flow rate

Combustor Analysis for 3

different moisture content

(20%, 30%, 40%)

Calculation of Overall

Efficiency

Various Design Points

Sensitivity Study Optimum Design point for

minimum COE

47

Table 6.1: Efficiency of Rankine

Inlet Condition of Turbine (P & T) Efficiency (%)

800 psi, 840F 29.86

600 psi, 640F 26.35

400 psi, 444.7F 24.3

We have considered wood chips with 3 different moisture contents and calculated the air by fuel

ratio for complete combustion of the Biomass Fuel. The table (6.3) shows the mass flow rate of the air.

Table 6.2: Air/Fuel Ratio

Moisture Content of fuel (%, wet basis) Air/ Fuel Ratio

20 5.22

30 4.847

40 4.5

For all the inlet conditions and along with the Air/Fuel ratio, we have calculated the mass flow rate

of the fuel for the combustor using the below given formula.

Mass flow rate of fuel (m) = Desired power output / (LHV * Overall efficiency)

where, LHV – low heat value (BTU/lb)

m - Mass flow rate is in lb/hr

The below table show the mass flow rate at different inlet condition of the turbine.

48

Table 6.3: Mass Flow rate and Cost of Fuel

The above table calculates the cost of fuel and the mass flow rate of fuel required to generate 3MWe.

The overall efficiency is calculated and the design points are given in the below table.

Figure 6.2: Cost of Fuel vs Mass flow rate of fuel

Sr.No.Moisture Content(%, wet

basis)LHV (BTU/lb) Pressure(Psi) Temp(F)

Mass flow

rate of

fuel(lb/hr)

Total Fuel

Energy,

MMBTU/year

1 800 842 5238.18335 375075.9622 $0.019 99.525484 $871,843.24 2.3244 0.243789 0.19401

2 600 640 5873.114665 420539.7152 $0.019 111.58918 $977,521.20 2.3244 0.212039 0.20567

3 400 442 6142.960474 439861.8103 $0.019 116.71625 $1,022,434.34 2.3244 0.179371 0.21033

4 800 842 6420.742924 375061.0071 $0.016 104.71827 $917,332.04 2.4458 0.284 0.2148

5 600 640 7198.533785 420494.8497 $0.016 117.40355 $1,028,455.08 2.4458 0.247 0.2277

6 400 442 7531.872725 439966.4965 $0.016 122.8401 $1,076,079.24 2.4458 0.209 0.2329

7 800 842 7095.357446 375427.7081 $0.015 107.44545 $941,222.10 2.5071 0.306098 0.2258

8 600 640 7936.641439 419941.508 $0.015 120.18506 $1,052,821.14 2.5071 0.265761 0.23909

9 400 442 8309.663586 439678.7588 $0.015 125.83376 $1,102,303.74 2.5071 0.224987 0.24463

10 800 842 7730.288761 375229.1033 $0.014 109.7289 $961,225.14 2.5617 0.302855 0.23569

11 600 640 8650.939168 419917.5797 $0.014 122.79723 $1,075,703.70 2.5617 0.263492 0.24962

12 400 442 9055.707882 439565.0995 $0.014 128.54278 $1,126,034.79 2.5617 0.222921 0.25538

2. Inflation adjusted according to http://data.bls.gov/cgi-bin/cpicalc.pl

1. Wood Fuels Handbook by AE biomass. (www.Biomasstradecenters.eu)

CoE

Note:

Total

efficicency

Beginning of

life Fuel Cost,

$/MMBtu

5541.108987

Cost(8760hrs)Rate ($/lb) Cost ($/hr)

20

30

40

Mass Flow Rate of Fuel (Wood Chips)

0 (Ideal) 8173.996176

6668.260038

6040.152964

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

$800,000.00 $1,000,000.00 $1,200,000.00

Ma

ss f

low

rate

(lb

/hr)

Cost of Fuel per year

Cost of Fuel vs Mass flow rate of Fuel

0

20

30

40

Moisture

Content

Moisture

Content (%,

wet basis)

49

Overall efficiency of the Power Plant was calculated using the below formula and the values are in table

Overall efficiency = Efficiency of Drier * Efficiency of Power unit * Efficiency of combustor

From this we calculated the fuel required per year which is,

Fuel required/per yr = Amount of the fuel required per hour (lbs) * 8760

Table 6.4: Overall Efficiency of the Plant for all Design Points

Design

Points

Moisture

Content of

Fuel (%)

(wet basis)

Inlet Condition

at Turbine (P &

T)

Mass Flow rate

of Fuel (lbs/hr)

Overall

Efficiency (%)

1

20

800 psi, 840F 6420.74 28.36

2 600 psi, 640F 7198.53 24.7

3 400 psi, 444F 7531.87 20.90

4

30

800 psi, 840F 7095.35 28.36

5 600 psi, 640F 7936.64 24.7

6 400 psi, 444F 8309.66 20.90

7

40

800 psi, 840F 7730.28 28.36

8 600 psi, 640F 8650.93 24.7

9 400 psi, 444F 9055.70 20.90

50

6.2.3 The Steam Turbine and Generator Cost Model

The table below indicates the overall cost of installation of the Steam turbine and Generator for the

different inlet conditions of the turbine.

Table 6.5: Steam Turbine and Generator Cost

The cost for the Items was decided by the Fraction of F.o.B column. The values of this column were

obtained from Dr. Steven Trimble Class notes for MAE 598: Energy Systems Design.

Exhaust Temp.

= 1800 F Inlet Steam Temp. = 640 F Inlet Steam Temp. = 440 F

Inlet Steam Pressure = 600 psi Inlet Steam Pressure = 400 psi

Sr.No. ItemFraction

of F.o.BCombustor Cost Boiler Cost

Turbine and

GensetBoiler Cost

Turbine and

GensetBoiler Cost

Turbine and

Genset

1 F.o.B (Cp) 1*Cp $1,125,000.00 $1,500,000.00 $1,750,000.00 $1,300,000.00 $1,600,000.00 $1,200,000.00 $1,550,000.00

2

Materials used for

installation 0.77*Cp $798,750.00 $1,065,000.00 $1,242,500.00 $923,000.00 $1,136,000.00 $852,000.00 $1,100,500.00

3 Direct Labor 0.63*Cp $708,750.00 $945,000.00 $1,102,500.00 $819,000.00 $1,008,000.00 $756,000.00 $976,500.00

Sub-Total 2.34*Cp $2,632,500.00 $3,510,000.00 $4,095,000.00 $3,042,000.00 $3,744,000.00 $2,808,000.00 $3,627,000.00

4 Frieght, insurance 0.14*Cp $157,500.00 $210,000.00 $245,000.00 $182,000.00 $224,000.00 $168,000.00 $217,000.00

5 Construction Overhead 0.44*Cp $495,000.00 $660,000.00 $770,000.00 $572,000.00 $704,000.00 $528,000.00 $682,000.00

6

Contractor Engineering

Exp. 0.26*Cp $292,500.00 $390,000.00 $455,000.00 $338,000.00 $416,000.00 $312,000.00 $403,000.00

Sub-Total 0.84*Cp $945,000.00 $1,260,000.00 $1,470,000.00 $1,092,000.00 $1,344,000.00 $1,008,000.00 $1,302,000.00

7 Contingency 0.48*Cp $540,000.00 $720,000.00 $840,000.00 $624,000.00 $768,000.00 $576,000.00 $744,000.00

8 Fee 0.10*Cp $112,500.00 $150,000.00 $175,000.00 $130,000.00 $160,000.00 $120,000.00 $155,000.00

Sub-Total 0.58*Cp $652,500.00 $870,000.00 $1,015,000.00 $754,000.00 $928,000.00 $696,000.00 $899,000.00

$4,230,000.00 $5,640,000.00 $6,580,000.00 $4,888,000.00 $6,016,000.00 $4,512,000.00 $5,828,000.00

$4,555,710.00 $6,074,280.00 $7,086,660.00 $5,264,376.00 $6,479,232.00 $4,859,424.00 $6,276,756.00

1.The quotes provided were for USD 2010, Inflation adjusted according to http://data.bls.gov/cgi-bin/

2. The boiler prices include economizer, sootblowers, ash hoppers and boiler trim.

Note :

After Infaltion Adjustment

Grand Total

Inlet Steam Temp. = 840 F

Inlet Steam Pressure = 800 psi

Steam Turbine And Genset Cost

Direct Materials

Indirect Expenses

Other Expenses

51

6.2.4 The Combustor and Dryer Cost

The following table as used to calculate the costs for Combustor and dryer. The Dryer cost for the

initial/ reference value was calculated as the 0.25 times the Boiler cost. The values for the cost are in 2010 USD

so they were adjusted according to the US government inflation adjustment calculator.

Table 6.6: Combustor and Dryer Cost

The cost estimation were done using the following formulae (obtained from Dr. Trimble notes)

Where,

C = cost for size of item of interest

Cr = reference case cost

S = size of item of interest

Sr = reference case size

m = scaling exponent (0.5 in our case)

Sr.No. Item Reference Actual Reference Actual Reference Actual

1Fuel Flow

Rate((lb/hr))6420.742924 6420.742924 6420.742924 7198.533785 6420.742924 7531.872725

2Dryer Cost( =

0.75)$200,000.00 $217,908.45 $225,433.40

3

Gas Flow

rate(lb/hr) 19,047.94 19,047.94 19,047.94 30,635.44 19,047.94 33,333.89

4

Combustor Cost(

= 0.85) $4,555,710.00 $4,555,710.00 $6,823,005.54 $7,330,581.26

$4,755,710.00 $7,040,913.99 $7,556,014.66

2. Dryer Cost is considered to be 0.25 times the boiler cost.

Combustor and Dryer Cost

1. Inflation adjusted according to http://data.bls.gov/cgi-bin/cpicalc.pl

Inlet Steam Pressure = 400

psi

Inlet Steam Temp. = 445 FInlet Steam Temp. = 850 F

Inlet Steam Pressure = 800

psi

Inlet Steam Temp. = 640 F

Inlet Steam Pressure = 600

psi

Grand Total

Note :

52

6.2.5 Cost of Installation of the plant

The Cost of Installation was calculated using the inflated costs calculated from the previous tables.

Table 6.7: Cost of Installation

The following plot explains the relation between the plant efficiency and plant cost. We observe that the

maximum efficiency was obtained for the plant with lowest cost.

Figure 6.3: Plot to decide the cost effective plant setup

Sr.No. Inlet Conditions Dryer Combustor Boiler Turbine and Genset TotalPlant

Efficiency

1 P = 840 psi, T= 800 F $200,000.00 $4,555,710.00 $6,074,280.00 $7,086,660.00 $17,916,650.00 0.28

2 P = 640 psi, T=600 F $217,908.45 $6,823,005.54 $5,264,376.00 $6,479,232.00 $18,784,521.99 0.25

3 P = 440 psi, T= 400 F $225,433.40 $7,330,581.26 $4,859,424.00 $6,276,756.00 $18,692,194.66 0.21

Cost Installation

$17,000,000.00

$18,000,000.00

$19,000,000.00

0.200.210.220.230.240.250.260.270.280.290.30Pla

nt

Cost

, ($

)

Efficiency,

Plant efficiency vs Plant Cost

53

6.2.6 Cost of Electricity (CoE)

The Cost of electricity (CoE) was calculated using the costs and data obtained from the previous calculations

above. Some of the assumptions include the FCR, CF and O&M charges. The minimum CoE was obtained for

the 800 psi and 840 F. Hence we have selected these inlet conditions for our turbine.

Table 6.8: Cost of Electricity Calculations

Note: CoE units are in $/kWh.

Inlet Steam Temp. =

840 F

Inlet Steam Temp. =

640 F

Inlet Steam Temp. =

440 F

Inlet Steam Pressure

= 800 psi

Inlet Steam Pressure

= 600 psi

Inlet Steam Pressure =

400 psi

1

1.1 Fixed charge rate, FCR($) 0.18 0.18 0.18

1.2 Capital Cost, CI($) $17,916,650.00 $18,784,521.99 $18,692,194.66

1.3 Capcity Factor, CF 0.7 0.7 0.7

1.4 Rated Capcity, (MWe) 3 3 3

Fixed charges($) 0.175309687 0.183801585 0.182898186

2 O& M Charges($/kWh) 0.01 0.01 0.01

3

3.1Beginning of life Fuel Cost,

$/MMBtu2.45 2.45 2.45

3.2

3.2.1 Rankine cycle Efficiency 0.2986 0.26 0.22

3.2.2 Dryer Efficiency 1 1 1

3.2.3 Combustor Efficiency 0.95 0.95 0.95

Total Efficiency 0.2837 0.2470 0.2090

Fuel Charges 0.029486022 0.033863563 0.040020574

4 Cost of Electricity, CoE $0.2148 $0.2277 $0.2329

2. The Value of FCR, Capacity Factor and O&M charges were referred from Dr.Trimbles MAE 598 class notes.

Turbine Input ConditionsSr. No.

Cost of Electricity Calculations

Note:

1. Inflation adjusted according to http://data.bls.gov/cgi-bin/cpicalc.pl

Overall Plant Efficiency

Fixed Charges

Fuel Cost($)

54

6.3 DFMEA

Design Failure Mode Effective Analysis (DFMEA) is a method used in many industries to figure out

what are the possible failures of the system, what are its possibilities of occurrences, what is the severity and

how can a failure which is occurring could be detected. DFMEA combines the 3 potential things stated above

(i.e. Probability of occurrences (P), Severity of the failure (S) and its Detection rate (D)) to find the Risk

Priority Number (RPN). RPN predicts whether the design is acceptable or not. A pre-defined table is present to

check whether the obtained RPN is satisfactory or not and this pre-defined table is based on the probability,

severity and detection.

The Priority and severity reference sheet is shown at the appendix based on which the team

calculated RPN. The below table shows how the RPN is calculated.

Table 6.7: Risk Priority Number

As shown in the above table, there are certain values which are in unacceptable range meanwhile

some have low risk. A to E represents the Probability of failure occurrence while I to VI represents Severity of

the failure.

55

The below table shows the DFMEA for the Biomass Power Plant.

Table 6.8: DFMEA for Biomass Power Plant

The above table shows the potential 5 majors failures that might occur, with their severity, detection

rate and what action is required to stop the failure from damaging the entire system. As one can see, all the

failure which might occur have acceptable risk factor and so design which we have selected can go on to real

world and potentially there won‟t be any failure.

Item Potential

Failure mode

Causes Prob -

ability

Severity Detection RPN

Turbine Corrosion of

Blades

Moisture content

of steam

D IV Moderate High

Combustor Explosion of

Boilers

Over-heating of

Combustors

A V Low Moderate

Pipe flow Leakage of

Steam pipes

High pressure &

Maintenance deficiency

B II Moderate Low

Heat

Exchanger

Wear damage High pressure C III Low Moderate

Pump Neglect to

Pump water

Maintenance Deficiency B II High Low

56

6.4 System Optimization

The main aim of the project is to provide cheap electricity and the team planned to optimize the Cost of

Electricity (COE). COE depends on the following variables and team studied the sensitivity of each variable

with the cost of electricity and found the sweet point of each variable.

Sensitivity study was done for the following variables,

Mass Flow rate of the fuel

Overall efficiency of Plant

Moisture content of Fuel

Mass Flow Rate of Fuel vs Cost of Electricity

The relationship between the mass flow rate of fuel and the COE is shown in the below figure.

Figure 6.3: COE vs Mass Flow Rate of Fuel

As shown in the figure the COE increases with mass flow rate of fuel required per year. And it is

clear the mass flow rate has to be minimum.

$0.22

$0.22

$0.23

$0.23

$0.24

$0.24

$0.25

370000 380000 390000 400000 410000 420000 430000 440000 450000

CO

E

Mass Flow Rate of Fuel (MMBTU/yr)

COE vs Mass Flow rate of Fuel

COE vs Mass Flow rate of Fuel

57

Overall efficiency of Plant vs Cost of Electricity

The relationship between the overall efficiency and the COE is shown in the below figure.

Figure 6.4: COE vs Overall Efficiency

As shown above the COE increases when the efficiency is less and it is clear it is better to choose

better efficiency plant.

Moisture Content of Fuel vs COE

To determine the minimum cost of electricity we have to plot all the CoE against the mass flow

rates of the fuel. We hence infer that the minimum CoE is for the case where the inlet condition of the

steam are P=800psi and T=840 F.

0.19

0.2

0.21

0.22

0.23

0.24

0.25

0.26

0.2 0.22 0.24 0.26 0.28 0.3

Cost

of

Ele

ctri

cit

y,$/k

Wh

Plant Efficiency

Comparison of CoE and Plant Efficiency

MC_0

MC_20

MC_30

MC_40

58

The relationship between the Moisture Content of Fuel and the COE is shown in the below figure.

Table 6.5: COE vs Moisture Content of Fuel

The above figure shows that COE increases with respect to increase in Moisture Content of Air. So lower

the moisture content its better.

0.17

0.18

0.19

0.2

0.21

0.22

0.23

0.24

0.25

0.26

5000 6000 7000 8000 9000 10000

Cost

of

Ele

ctri

cit

y, C

oE

($/k

Wh

)

Mass Flow Rate of Fuel (lb/hr)

Mass flow rates vs CoE for Different Moisture Content

MC_0

MC_20

MC_30

MC_40

59

6.5 Trade Study

Following are the major components which have major contribution in plant cost and being used for trade

studies.

1. Steam Turbine

2. Combustors/ Boiler

3. Condenser

Table 6.9: Trade Study of Components

Steam Turbine Technical Specifications Decision

SVSS, Back Pressure

Condensing By Elliott

Ebara

50 kW- 2.6MWe

Inlet Pressure= 900 Psig

Inlet Temp= 900 F

Rentech

Rentech 3.0 MWe

Inlet Pressure 800Psi &

Temp= 850F

MARC 1( Modular

Arrangement Concept)

MAN Steam Turbines

2-3.5MWe

Inlet Pressure =870 Psi

Inlet Temp=842 F

Boilers

Rentech Boiler Outlet Condition

Pressure= 800 Psi & Temp

850 F

Rentech

Steam Condenser

Plate type –Alfa Laval

make

Shell & Tube Type

Shell & Tube Type -

Double Pipe Heat

Exchanger

60

Comments:

Rentech make of steam turbines are used for analysis because we are having technical and cost data for

these turbines.

Boiler make is Rentech and cost data has been provided by the instructor.

Steam condenser is selected based upon compact design, ease of maintenance.

61

7.1 Schedule

A Gantt chart showing the actual progress of the team is shown in figure 8.1. This Gantt chart helped

the team keep track of the amount of work for each phase of the project. The chart helped the team keep track of

the milestones and the deadlines to be met. The labor put in was in accordance with the requirements of the

chart. More time was spent on the more difficult tasks at hand.

Figure 7.1 Gantt chart showing team progress

The importance of meeting deadlines and staying on course with the plan was realized early on. Team

meetings were held every week and appropriate progress was made at every meeting. The minutes of the

meeting were recorded in the team notebook. The team notebook contains the research done by all team

members while also identifying the possible roadblocks and limitations as a team. An initial estimate of the time

required for the various phases of the project was drawn out and efforts were made to stick to the plan.

Whenever the team faced bottlenecks during the process, the team members helped each other out and ensured

that the schedule was followed accurately. Once a particular task was accomplished, the team consulted with

Dr. Trimble and asked for his review. This ensured that a task once completed did not require more time later

on.

62

7.2 Labor Budget

The comparison of the allotted time for the project to the actual time spent by the team was an important

performance metric. The time required to complete the project was estimated to establish a budget. This was

then compared with actual time spent by the team and used to monitor the team performance and to ensure that

the labor spent was not falling below expectations. This is shown in graph 7.2.

Table 7.1 Labor Chart for Biomass Power Plant

Labor Hour Table

Task

Working

days Planned Actual

Cumulative

hours

Cumulative

hours

1 Research 40 40 48 40 48

2 Project Plan 15 30 36 70 84

3 System Requirements 7 20 24 90 108

4 Concept Generation 8 15 18 105 126

5 Trade Studies 8 15 18 120 144

6 Final Conceptual Design 11 30 36 150 180

7 Budgetary studies 8 15 12 165 192

8 Thermodynamic Model 8 30 24 195 216

9 Cost Model 7 15 12 210 228

10 State Point Diagrams 8 15 12 225 243

11 Hand Drawings 1 15 12 240 255

13 DFMEA 1 15 12 290 267

14 Sensitivity Study 6 15 12 305 276

15 Final Design Description 8 30 40 335 316

16 Final Report 6 30 35 365 354

17 Final Presentation 2 30 25 395 376

360 376

63

The below figure shows the labor chart with actual work done and the planned working hours.

Figure 7.2 Labor Chart Biomass Power Plant

0123456789

101112131415161718

0 75 150 225 300 375 450

Task

Nu

mb

er

Hours

Labour Chart fo Biomass Team

Planned Hours

Actual Labour Hours

64

8. Project Conclusion

The following conclusions were made by the design team based on analysis.

The cost of electricity was calculated to be $ 0.229/kWh

The rated output of the plant was 3MWe

Exhaust stack temperature was found to be 350 F.

Components selected in Preliminary Design are according to the Emission Standards specified in

appendix.

In final design, the dryer should be designed to bring moisture content of fuel to twenty percent

Based on fuel consumption calculation fuel storage area should be designed in final design to

accommodate 800,000 pounds of fuel.

Arrangement has to be done for proper waste water and ash disposal.

The team finished the project on 8th

May which was at par with the planned date. The labor budget also

was in line in with the planned budget. The team realized that teamwork was the key to success. The team also

learnt about how to do research on various topics. The team understood the importance of maintaining good

communication during the entire process quite early on in the project and established various methods to ensure

that every team member was well informed about the progress and their respective roles. The team also learnt

that unforeseen circumstances can often affect the project schedule and it is important that an appropriate

cushion time be provided in the project plan to compensate for the same.

65

9. Recommendation

The below are the main recommendations for the implementation of Biomass Power Plant.

The cost of electricity was found to be high compared to conventional methods of producing

electricity. The team therefore recommends that the customer consider increasing the capacity of

plant to about 100MWe as the capital cost would increase marginally but the cost of electricity

would reduce drastically.

The team also recommends installing the plant at a location where wood chips are easily

available in abundance and where easy disposal of waste water and ash is possible

More detailed analysis of turbine inlet condition could be done to obtain optimum plant

efficiency and lowest cost of electricity.

Action have to be taken when the failure of components is detected to minimize severity and

probability of the failure mode.

66

10. Appendices

10.1 Appendix for section 4. Requirement

National Ambient Air Quality Standards (NAAQS) table is shown below.

Table 10.1: Emission Standards

10.2 Appendix for DFMEA

The Probability of Failure rate is selected based on the below table.

Table 10.2: Probability of Failure (Reference)

67

The Severity in section 6.3 is selected based on the below table.

Table 10.3: Severity of Failure