quality of fuels used in boilers.
In boiler operation and performance the quality of fuels play an important role.
1. Normally we uses solid, liquid and gas as fuels in operating the boilers.
2.The solid fuels are coal, wood, brickets, bagasse, paddy husk etc.
2. The liquid fuels are furnace oil, LDO, HSD, concentrated liquors from process plants, etc
3. Gaseous fuels are CNG, BIOGAS, PRODUCER GAS etc.
4.Since Gaseous fuels are very clean we may not experience much of operational problems.
5. Liquid fuels barring furnace oil are also clean as such operational problems are less but furnace oil fired boilers face lot of problems .
6.Solid fuels boilers are one which normally encounter lot of problems. we will focus more on solid fired boilers particularly coal fired boilers.
The quality of coal play major part for operational problems in a boiler. There are many grades of coal available which can be classified from GRADE A to GRADE H.
grade A is good quality and grade H be the worst quality. normally grade A and B are used in large scale power plants and the normal process industries will uses mostly grade C are lower. There are imported coal are used in boilers. The main problem in the Indian coal is high percentage of ash content. The medium scale process industries normally use high ash content coal because it is cheaper than imported coal in which ash content is significantly less. This high ash percentage will poses major problems in boiler operation. This ash get deposited in outer surface of boiler tubes in water tube boilers and inside in smoke tube boilers. this ash deposit over tubes reduces heat transfer and thereby boiler efficiency. though soot blowing and air lancing operations removes most ashes from tube surfaces, still will not remove all. For this reason we will take periodical cleaning of boilers.The other solid fuels such as bagasse, husk are also create this problems but to lower extent. Though we know the problem of ash, we don't have any other options considering the economic in operating the industries. sulphur is another content in coal which creates corrosion problems in furnace grate, flue gas passages, ducting, and chimney. flue gas desulfuricatipn (FDG) is remedy for this problem but not viable for its high costs.
Calorific Value of fuel namely NCV net Calorific value of fuel plays on boiler performance and not GCV. since GCV gross Calorific value is includes hydrogen heating value which is not useful for heat transfer in boilers.
Boiler Manufacturers always shows efficiency based on GCV rather than NCV.
to show higher figures.
Preparation of coal for boiler such as screening, sizing, segregation improves boiler performance.
Don't get fooled by c.v.figure of coal coal suppliers. it is the figure of dried coal and the as supplied which we use in boilers normally.
further information one can always contact me by mail or phone given below.
K GOPALAN.
Kgopalan1956@gmail.com
9429663740/9208956202
