E Biomassa 825-Gimelli

8/12/2019 E Biomassa 825-Gimelli

1/6

European Associati

Development of Renewable Enand Power Quality (

2.3Experi

1 DIME Departmant of Mecha2 Faculty of Engineering, Un

Abstract.The present paper shows the experimentanalysis of a biomass plant from maximMW. This is a classical Steam Powmaximum pressure of 48 bar andtemperature of about 430 C at the desigis significantly smaller than the meansystem [1], [2], [3], [4], but maintains a r(about 22.9%) of the Global Electric EfficThe analysis was conducted using ecollected directly on the Power Plant, atand thus validating thermodynamic model

The difficulty in collecting the experimtype of system, is mainly due to the enoof the lower heating value of biomass,large variability of the load and theparameters. Combustion simulation wexperimental data (Flue gas temperaturflow) and the results allowed the evaluaticomposition that is within the rangeliterature [5].Different Plant configurations werevaluated to plug the power fluctuationsof biomass. A 100 kWe Natural Gas fTurbine (MGT) was numerically connect

Steam Power Plant (BSPP) to evaluate tpower fluctuations and on the Global ElA MGT thermodynamic scheme has beeproperly, validated with experimental da[6] e [7]. It is designed to send the hot gthe exit of the MGT in the combustiomain system, thus creating a MGT-SAnalysis of the results of this couplinimprovement in terms of efficiencystability.

Key words

Biomass Power Plant, ThermodynaThermochemical Processes, Steam TurTurbine.

n for thergies, EnvironmentA4EPQ)

International Conference on Renewab(ICREPQ

Santiago de Compostela (Spain),

W Biomass Steam Power Plant:ental and Thermodynamic Analysis

A. Gimelli 1, A.Luongo 2

ical and Energy, Univ. degli Studi di Napoli Federic

iv. degli Studi di Napoli Federico II , alessa.luongo@

al and numericalum power of 2.3r Plant with aa turbine inletn point. The sizeof this type oflative high valueiency.perimental data,the Design Point,s.

ntal data of thisrmous variabilitywhich involves an the operatingas validated bye, air flow, fueln of the biomassreported in the

e, numerically,due to variabilityelled Micro-Gasd to the Biomass

e benefits on theectric Efficiency.n developed and,ta from literatureses coming fromchamber of the

T Power Plant.has noticed an

and operational

ic Analysis ofbine, Micro-Gas

1.

IntroductionBiomass is a term for all orgplants (including algae, trproduced by green plants cmaterial through photosyntand water-based vegetation,The biomass resource canmatter, in which the enerchemical bonds. When thcarbon, hydrogen and oxygdigestion, combustion,substances release their stor

has always been a major sand is presently estimated t14% of the worlds energy sThe processes currentlycategories: thermochemicalprocesses (Fig. 1). Amonprocesses we find the directpyrolysis, while the biocaerobic and anaerobic digest

Fig. 1. Biomass Conversi

Although the direct combform of energy conversiproblems when the biomassthese cases biomass cant bpenalizes the production of

le Energies and Power Quality12)28th to 30th March, 2012

II, [email protected]

tudenti.unina.it

anic material that stems fromes and crops). Biomass isnverting sunlight into plantesis and includes all land-

as well as all organic wastes.be considered as organic

y of sunlight is stored ine bonds between adjacentn molecules are broken by

or decomposition, thesed chemical energy. Biomass

urce of energy for mankindcontribute of the order 10-

pply [8].sed are divided into twoprocesses and biochemicalthe main thermochemical

combustion, gasification andhemical processes are theion proceedings [1].

on Technologies Scheme.

stion is the most commonn, it creates insuperablehumidity is high, in fact indirectly burned. This factordirect combustion biomass


2/6

energy because it is not always availabiomass and the needed amount.In this contest, its important to considepower, but the efficiency is penalizedsystem has relative low power (2.3 Mpenalize very much the global electric efdesign point) [1], [2]. So, its justifieperform an experimental and numericalrelative small Steam Power Plant.Also alternative layouts have been invsolutions to reduce the mentioned prohumidity and relatives fluctuations.These layouts have been numerically carrthermodynamic and thermo-chemical anPlus [9]. [10], [11].

2. Description of Steam power

As said, the steam power plant (scheme ipoint generates 2.3 MWe through dire

woody biomass.The plant (Fig. 2) consists of: Combustion chamber (CC Fi

separated from the steam generat Steam generator (GV Fig. 2

natural circulation of water wisuperheater and economizer;

Steam turbine (T Fig. 2) is a 1first one is an action stage andreaction stages. There is a bleethe fifth and sixth stage;

Flue gas cleaning system (F Fimulti-cyclone and a bag filter;

Condenser (C Fig. 2) at ground

Fig. 2. Layout of Biomass Steam Power

3. Experimental analysis of BiPower Plant (BSPP)

The measurements of experimental dadifficulties due to the continuous variatioconditions. The biomass has a high hu

le low humidity

Plants with low[3]. The present) but it doesnt

iciency (0.229 @the interest to

analysis of this

estigated to findblems about the

ied out through alysis with Aspen

lant

Fig. 2) at designt combustion of

. 2) physicallyor;) , type vertical,th vertical tubes,

stages unit: thehe others are thed steam between

.2) consists of a

ater.

lant (BSPP).

omass Steam

ta present someof the operatingidity variability

causing a change of LHV anconditions. The nominal ponumerous measurementsconditions are reported in trepetitive values).In the following chart (Charof the combustion chambebigger electric power variatemperature is, also, controllit can be seen from Chart 1,the Power Stability.

Chart 1. C.C. temperature t

The experimental data collanalysis have been integrate

Experimental data: Ambient cond (Table I);

Steam Turbinand expansitemperature aof the thermod

Boiler : mass flof the exhaust

Indirect data (Table

Combustion ef

Efficiency of t

Cycle : ter =

Mechanical ef

Global Efficie Global Electri

b

negel

m

P=

&

,

Composition abiomass (Tabl

0 0.4 0.8Ti

800

820

840

860

880

900

920

940

TemperaturePower C. C. TemperatureNet Pow er @ Nom

, consequently, of operatingint has been identified withnd the relative operative

he Table I (more stable and

t 1), the continuous variationgas temperature generates

tions. Combustion chambered by an EGR valve, but, asits not sufficient to control

ends and Power Generated.

ected and used for energywith indirect data:

itions : temperature, pressure

: electric load, compressionn ratio, loss of load,d pressure at various pointsynamic cycle (Table I);ow temperature and pressuregas at various points;

II and Table III):

iciency: bib

f t b

H m

P

=

&

,

e Real Thermodynamic

lim,

lim

,lim P

PPP

PP r

f t f t

r i

==

iciency :r

uam P

P=

cy: mter bg =

al Efficiency :

bi

t

nd lower heating value ofIII).

1.2 1.6 2e, h

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

2.1

2.2

2.3

2.4

@ Nominal Point inal point


3/6

Points Fig. 2 Temperature (C) Pressure (bar)

BurnedGas fromthe SGCC

Fumes 1 933.0 0.998

Fumes 2 262.4 0.998Fumes 3 171.3 0.998Fumes 4 171.3 0.998

Chimney 110.0 1.004

Water inthe

Thermo-dynamic

Cycle

1 24.1 0.030

1'

24.1 3.0001 '' 80.0 2.0001p 97.0 1.5001R 111.3 1.5002 111.8 55.0003 428.7 47.500A 296.7 11.000A' 284.7 1.5004 24.1 0.030

Air 1 21.7 1.004Air 2 125.0 1.004

Table I. - experimental conditions @ nominal point.

Experimental data Simulation data

b 0.903 0.905

ter 0.341 0.342

m 0.806 0.805

g 0.248 0.249

el 0.229 0.229Table II. - Efficiencies @ Nominal Point.

The evaluation of the biomass composition and its lowerheating value was obtained iteratively with the help of athermodynamic simulation software verifying that thecomposition assumed for the biomass and therefore thelower calorific value, realized the same operatingconditions of the experimental data.

Water 46.5%

Average BiomassComposition

Carbon 33%Oxygen 17%

Hydrogen 2%Nitrogen 0.5%

Ash 1%LHV [MJ/Kg] 14.6

Table III. - Biomass Composition and Lower Heating Value.

4. Thermodynamic model of Biomass SteamPower Plant

A thermodynamic simulation of the plant (Fig. 2),energetic and chemical phenomena, has been carried out;the simulation scheme has been validated by experimentaldata. The simulation has been used to verify the biomasscomposition and LHV.Have been supplied the following inputs:

ST and Pumps Efficiencies; Temperatures and pressures of the working fluid in

all the thermodynamic cycle (Table I); Heat Exchangers Sizes;

Fuel and Combustion Air Flow and Composition;The outputs returned are the following:

Flue Gas Temperature in the CC (Fig.2); Turbine Power Output; Thermal Power transferred from the flue gas to the

motor fluid; Pumps Power; Efficiencies Values.In particular, the flue gas temperature has been used as

test. The tables (Table II and Table IV) showcomparisons between the experimental and numericalflue gas temperatures (Table IV) and the comparison ofefficiencies (Table II). It is clear that the compositionassumed for the biomass is very close to the real meanvalue.

Temperatureexperimental

data (C)

TemperatureSimulation

(C)Fumes 1 933.0 936.6

Fumes 2 262.4 261.4Fumes 3 171.3 170.4Fumes 4 171.3 170.4Chimney 110.0 109.3

Table IV. - Flue gas temperatures comparison.

Different Plant configurations were, numerically,evaluated to plug the power fluctuations due to variabilityof biomass. A 100 kWe Natural Gas fuelled MGT wasnumerically connected to the BSPP. It is designed to sendthe hot gases coming to the discharge of the MGT, in thecombustion chamber of the main system, thus realizing aMGT-ST.

4.1 Turbec 100 kWe MGT Validation Model

To analyze different Plant layouts, a thermodynamicmodel of the MGT (Fig. 3) has been implemented. It hasbeen validated with experimental data from literature ([6]and [7]).

Fig. 3. TURBEC 100kWe MGT model.

Input simulation data are reported in Table V. Validationis confirmed by the good approximation betweenexperimental and numerical comparison reported in theTable VI. A natural gas supply compressor has beenconsidered because is necessary a pressure of 6 - 8 bar tointroduce the NG in the Combustion Chamber. Thiscompressor is electrically powered and, therefore, it

results a reduction of net electrical power output. It hasbeen, also, necessary to introduce an air exchanger tocool the exit gas from the compressor because a feed gastemperature between 0 C and 60 C is required.


4/6


5/6


6/6

E Biomassa 825-Gimelli

Documents

Transcript of E Biomassa 825-Gimelli