New Concept of Steam/Power generation from Waste Heat Recovery Boiler

Power Generation/ Steam Generation from W.H.R.B concept where waste heat is based over water filled boiler tubes and steam generated. The Heat value 780 kcal/NM3 and 1000 NM3 generates 405 kg/hr of steam.

a) Present Concept steam at 66 ata, 485oC generates from individual W.H.R.B (I,II & III ) & AFBCare combined in steam header and AFBC is controlled steam regulates steam turbine for Power generation.
In above case each boiler 10tph with 100 tpd Klin is costly . So 4 no. boiler with controls will come under IBR costly capital cost and heavy maintenance etc.

b) New Concept of technology to go for a single boiler WHRB and we are combining flue gas in mixing chamber by individual M.S Ducting before radiant chamber.

WHRB 100 tpd I,II,III Gas volume
3 x 24,000 NM3/ hr at 950oC
= 72,000 NM3/hr

Theoritically this can generate 0.405 x 72,000 NM3/hr
= 29 tph at 485oC

Power generation = 29/4.1
= 7MW


c) To increase the steam generation & to restore the fluctuation of gas volume from klin we can introduce one Cyclonic Gas Generator (CGS) to increase the volume of the fuel gas. The capacity of coal gasifier range from 20,000 – 50,000 NM3/hr. Thus we can increase steam generation vice versa power.

ADVANTAGES:

1. Small entrepreneur having single 100 tpd with gasifier can generate power.
2. 2 x 50 tph with combined gasifier can generate steam or power.

But since there is no control of steam generation in WHRB. All the power generated has to be consumed in grid or internal consumption, which will vary from case to case depending on working hours quality coal used etc.



Klin 3 no.s X 100 tpd having one 30 tph, 66 ata, 485 oC Waste Heat Boiler has been developed in M/S DEVI Iron and Steel , Dharsima , Raipur is under operation to generate 8 MW power feed to grid.

Now during running to maintain pressure in 100 tpd klin the feed rate of coal varies and resulting gas generation. Our prime objective was to get maximum fuel gas from each kiln. After attaining injection of dedusting coal fines in kiln.

Now new Concept we are attaching one coal gasifier (C.S.G ) at entry top of mixed chamber of WHRB. Capacity will 50,000 NM3/hr using 50% coal & 50% char (non magnetic).
Gasifiers are variable coal/char mixed bed can controlled the flue gas generation 60-100 % of its capacity.

Thus the concept of multi klin technology with single boiler will bring capacital cost of WHRB less easy to operate and pay back period is less. It has multiple advance and used of combined Gasifier, which will reduce cost of coal consumption. Because Gasifier are capable of burning 50% char & 50% coal and fuel feeding can be controlled from 60-100 % of rated capacity.

a) CSG are used to extract flue gas which is rich in carbon monoxide. Gas is used in preheating of furnaces in rolling mills.
b) CSG can be used in boiler for steam generation.