De-dusting Pipe Layout : An Ignored Aspect

Everyone is entitled to a pollution free environment and it is everyone’s moral obligation to

keep it that way. In line with

and healthy environment, India is

comply, industries are implementing highly efficient emissions control systems, such as state

of-the-art dust collectors/bag filters.

complemented by a properly designed piping sy

An adequate de-dusting pipe arrangement plays

overall system, and it is essential to

tocomply with local environmental

In order to achieve a well-designed plant

productivity and perform an analysis of

being made to optimize construction costs by looking into various building and equipment

arrangement options, there is a tendency to

piping arrangement. Leaving

construction of the plant has been completed

and legislative issues, additional costs,

shutdowns because of high dust emissions.

The design and layout of de

factors. Technical factors involve

layout, dimensions, etc. Non

dusting Pipe Layout : An Ignored Aspect

Everyone is entitled to a pollution free environment and it is everyone’s moral obligation to

keep it that way. In line with the concerted movement throughout the world

and healthy environment, India is issuing stringent laws to protect the environment. To

comply, industries are implementing highly efficient emissions control systems, such as state

art dust collectors/bag filters. However, to be fully efficient these systems need to be

complemented by a properly designed piping system.

dusting pipe arrangement plays an important role in the

essential tofollow a maintenance program tomonito

environmental standards and legislation.

designed plant, it is required to do research

perform an analysis of relevant processes. While we see considerable effort

to optimize construction costs by looking into various building and equipment

, there is a tendency to disregard the design of the de

Leaving the layoutof the de-dusting and pipe arrangement

ion of the plant has been completed has enormous consequences such as operational

additional costs, inadequate plant performance, and temporary

dust emissions.

Inadequatede-dusting pipe layout

The design and layout of de-dusting pipes depend on various technical and non

factors. Technical factors involve operational parameters, type of material

on-technical factors include outlet emission limits, stack height

dusting Pipe Layout : An Ignored Aspect

Everyone is entitled to a pollution free environment and it is everyone’s moral obligation to

throughout the world towards a safe

to protect the environment. To

comply, industries are implementing highly efficient emissions control systems, such as state-

ully efficient these systems need to be

important role in the performance of the

monitorits performance

esearchon how to improve

While we see considerable effort

to optimize construction costs by looking into various building and equipment

de-dusting system and

dusting and pipe arrangement until after the

has enormous consequences such as operational

inadequate plant performance, and temporary

on various technical and non-technical

operational parameters, type of materials/fines, building

technical factors include outlet emission limits, stack height

regulations etc. Adhering to technical and non-technical requirements provides forefficient

results,compliance with the law, and an eco- friendly environment.

Material handling operationsgenerate dust at various sources of a plant, such as transfer points,

crushers,dump hoppers,storage silos, packing areas,etc.The selection ofemission control

equipmentfor these sources should be done at the same time with an adequate and efficient

pipe arrangement.

The following factors should be considered when designing a pipe layout:

Sizing of pipes: The sizing of vent pipes dependson factors likegas velocity within the pipe and

vent volume to be picked up. Special attention mustbe given while deciding the

velocity for different types of fines. The gas velocity should be lowfor high

abrasive fines such as clinker dust, coal dust etc., whereas it could be higher for

low to moderate abrasive fines(e.g. raw meal dust). This shows that for the same

vent volume of clinker and raw meal dust, the pipe sizes vary.

Sizing of pick-up hood:Pick-up hoods at source points of dust generation should be sized for

low velocityin order to capture only the fine dust and not the processed

material.

Inclination of pipes:It is recommended to avoid horizontal pipes for de-dusting purpose. For

upward and downward flow directions, pipes must be laid with proper

inclination to avoid dust accumulation within the pipes.

Avoid false air entry:Flanged pipe joints are prone to leakages and invite false air entry creating

imbalance of the system.For that reason, welded joints should be favored

against flanged joints.There are exceptions where flanged joints are essential to

provide clear space for maintenance.

Avoid too many bends: Having too many bends and diversions in the pipe layout increases the

pressure drop and consequentially increases load on the fan. In addition to

increased pressure drop, pipe bends are prone to wear due to impact of abrasive

fines while changingthe flow direction.

Bend Radius: To allow a smooth change inthe flow direction, the radius for pipe bends

shouldbe largeenough. It is more critical for gases carrying dust. Pipes carrying

clean air may have bends with a radius as low as 1 times of the diameter of dust.

Pipe Branches: At pipe joints, the direction of branch pipes should always be towards the flow

and not in the opposite direction or perpendicular to the main pipe as it may

create turbulence and cause additional pressure drop. Expander pieces should

be provided atthe connection point of multiple pipes. Pipe diameter exactly after

the connection, should be in accordance to the combined vent volume of branch

pipes.

Dust Collection device: In cases where horizontal pipes cannot b

collection arrangement must be provided

Plate thickness:The plate thickness of vent pipes from

filter intake should be higher

fan. The plate thickness also varies for pipes carrying abrasive fines versus

carrying non-abrasive fines.

Limiting the number of dust sources

recommended

costs in mind. It becomes

with too many vent points

emissions.

Existing installation: Designing a de

always been challenging.

layout so that the existing system

regulations.

Thesebasic guidelines play a

the same time improving the overall performance ofthe plant

every aspect of the design while

the connection, should be in accordance to the combined vent volume of branch

In cases where horizontal pipes cannot be avoided,

arrangement must be provided; e.g. quick opening cleaning doors etc.

late thickness of vent pipes from the point of dust sources up to

filter intake should be higheras compared to pipes after the bag f

late thickness also varies for pipes carrying abrasive fines versus

abrasive fines.

dust sources: To keep a de-dusting system in balance,it is

recommended to connect as little as possible sourcesto

. It becomes operationally difficult to maintain

with too many vent points. Thus, the system becomes inefficient to handle dust

: Designing a de-dusting pipe layout within an existing building or

challenging. A detailed study is required to design an efficient pipe

the existing system is not affectedand stillcomplying with

Proper De-dusting pipe layout

a significant role in designing an efficient de-

the same time improving the overall performance ofthe plant. It requires

every aspect of the design whilemeeting all technical and legislative demands.

the connection, should be in accordance to the combined vent volume of branch

e avoided, a proper dust

e.g. quick opening cleaning doors etc.

dust sources up to the bag

pipes after the bag filter up to the

late thickness also varies for pipes carrying abrasive fines versus those

dusting system in balance,it is

to a bag filter, keeping

difficult to maintain the pressure balance

omes inefficient to handle dust

existing building or plant has

to design an efficient pipe

and stillcomplying with emission

-dusting system and at

requires a close review of

islative demands.

It not only gives the legal security and efficient system to the plant owner but also becomes

instrumental in saving the significant amount of money by controlling the dust emission and/or

material losses.

PENTA India recommends givingvalue to awell-designed de-dusting pipe layoutwhich

contributes to the efficient performance of the plant and a healthy environment too.

Manoj Thakur