7/28/2019 Coal Qualified

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Follow prabakaran

how the coal properties affect the boiler feed water temperature?In my knowledge coal properties

affec the boiler efficiency only.

4 days ago

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9 comments

Follow FUTAGOSHI

FUTAGOSHI PENNETT Dear Prabakaran, As far as my knowledge concerned, coal properties won'taffect feed water temperature at inlet of boiler. It may affect Steam temperature but it will be

compensated by spray or burner tilt or air flow control. Any way if coal properties are changed,

operator has to take care of feeding.... I also welcome comments on my statement... Thanks....

4 days ago Like1

Follow Kent

Kent Coleman There are many ways that coal properties affect the water temperature once it getsto the boiler, but not in the feed water system unless there is an effect on the extraction steam

properties which would only happen if you couldn't make Sh or RH temperatue (maybe change due

to use of spray desuperheater). Things of concern include heat content, ash fusion temperature, ash

content, corrosive element content, etc. The way the coal slags, fouls, and the grind ability all affect

the balance between radiant and convective heat in the boiler and can change the heat absorption

throughout the boiler. This leads to more or less heat being taken out in the waterwalls, affects the

furnace exit gas temperature (FEGT), heat absorbed in the sh/rh section, and temperature in the

economizer and air preheaters.

3 days ago Like3

Follow alok

alok bhattacharya Mr. Coleman has explained in comprehensive way how coal quality affects

boiler performance but most importantly boiler operator must know how to handle the generated

heat in boiler to avoid heat loss. I have seen even good quality of coal failed to generate

proportionate (quality / quantity) steam because of improper operation of boiler creating formation

of clinker. I may be slightly off from main question but equally important.

3 days ago Like1

7/28/2019 Coal Qualified

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Follow Ramos Samuel

Ramos Samuel Gultom Hi Prabarkan,

A scenario that I think could satisfy your question is when the coal quality goes really low that you

can't reach your nominal load. In this case your steam properties in the hot side of your HP/LP

heaters would decrease hence changing your final feedwater properties (but this is the same effect

as using as-designed coal but running the unit on partial load).

In contrary, if your coal quality was higher than design then all the steam properties would be

controled to meet as-designed properties either by governor and/or desuperheater spray and/or

burner tilting which would lead to as-designed final feedwater properties.

Either than said first scenario, I cannot think of a direct corelation between coal property &

feedwater property.

Maybe some of the more experienced guys could give in their thoughts?

2 days ago Like

Follow viswanathan

viswanathan govindasamy Hi Prabakaran

Can you clarify, if you mean the selection of feed water temperature at design stage or during

operation

1 day ago Like

Follow prabakaran

prabakaran s Thanku Mr.Ramos

1 day ago Like

Follow prabakaran

prabakaran s During operation

1 day ago Like

Follow Laurie

7/28/2019 Coal Qualified

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Laurie Thompson There is another unmentioned area where coal properties plays a part in

feedwater temperature and Boiler operation. That is the chemical qualities of the coal. We have had

trial deliveries of coal, from other than our normal suppliers, where the silica level has been high.

During combustion, a white, reflective ash builds up on both the water walls, and the economiser

tubing. This has the effect of pushing a lot of heat that would normally be absorbed in these areas

over into the superheater / reheater sections of the back pass.

We found that we were sootblowing every 6 hours, rather than once per day, struggled with low

economiser outlet temperatures, and poor furnace wall heat pick - up. The other by product of this

was very high superheater and reheater steam temperatures that the spray system had difficulty

controlling.

Should you decide to obtain your coal supplies from different areas, and different coal seams, be

careful to do a representative trial burn of the new coal prior to committing to purchase large

stocks. Thanks.

16 hours ago Like Reply privately Flag as inappropriate

Follow alok

alok bhattacharya @ Laurie,

What you have mentioned is certainly a possibility in boiler / feed water operation but in practice

where I worked, random sampling from coal rake ( around 30 wagons ) was done

to ensure the quality of coal which supplier is supposed to deliver. There was penalty in case of gross

deviation found but most of the time it was found within accepted norms. I am not aware, how

other plants handle this issue. Considering malpractices in coal distribution by supplier, constant

check is absolute must. Thanks.