Case Study- for WHRB - DEVI IRON & STEEL POWER Ltd Dharsima , Raipur

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WHRB boiler for 100 tpd sponge,steam output temperature problem raised from 400degC to 480degC

         Sponge Iron units running 300 tpd klin having WHRB to generate steam at 64 ata, 485degC considering gas from klin 72,000 nm³/hr at 950⁰C, over a period of long running have  detoriation of coal and iron ore quality. The total gas generation from klin has reduced for 100 tpd only 18,000 nm³/hrand ABC temperature  850⁰C.

The ideal 100 tpd klin with good quality coal (GCV 3500Kcal/kg) with less ash below 25%. Gas generation from 100 tpd klin is 24,000nm³/hr , 950^oC and steam generated 10.5 tph , 64 ata, 485^oC. Accordingly  turbine selected 64ata, 485⁰C and consumption of turbine of steam increases as less 420^oC and below turbine trips. In some cases due to low temperature steam and by pass of safety system of turbine which leads to entire rotor blade broken and major shut down of system.

DEVI IRON & STEEL POWER Ltd. Dharsima , Raipur is having combined 3x100 tpd WHRB (common boiler) 30 tph, 485⁰C. During operation we initially could not attain temperature of 430⁰C due to coal quality which varies from supplier to supplier and steam generation also low due to less gas volume.

Turbine operation became critical due to less temperature because trip was set 410⁰C at turbine inlet & vice versa steam consumption increased and generation was low.

To Incease the steam temperature. We have taken following step and success was tremendous.

1.       Super heater was placed in pass – 03 in previous design.

2.       1^st pass 850⁰C flue gas temperature water walls, 3^rd pass super heater where passing temperature was below 450⁰C and steam temprature 430⁰C max.

3.       We extended. Super heater of thick S.S heavy gauge horizontal coils in 1^st pass.

4.       The result we achieved immediately from even two klin at ABC temperature 900⁰C steam temperature 480⁰C-490⁰C .

5.       When steam temperature was high even less quantity of steam generation we can safely run the generation. However pressure are controllable.

6.       Devi Iron & Power Ltd. Running with grid operator 33 KV.

Note- My experience with WHRB steam generation it is possible to raise the steam temperature with a little modification in WHRB boilers. However basic design of boiler to be studied first and modificatio is possible.

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.

W.H.R.B (Waste Heat Boiler)

A waste heat which is being generated from W.H.R.B 100 TPD Klin of 24,000 NM^3/hr. this depends on Metalisation of sponge Iron and klin operation. presently Coal quality has deteriorated tremendously and accordingly gas volume decreases. for which many of the enterpruners telephonic contacted about Quality of Steam generation at 64 ata, 485 Deg C, for 10 TPH of Steam.

So, for above low Steam generation, let me explain the following reasons, which are as follows: -

(1) Low gas generation from Klin.
(2) Low capacity of Celler Fan.
(3) Coal Composition.
(4) WHRB Boiler design parameter i.e. economizer storage capacity.

So, the above problems can be solved following ways: -

(a) Increase the volume of air (Oxygen) to klin keeping full coal burning.
(b) Injection Coal fines in ABC Chamber or WHRB Boiler.
(c) Regulation economizer water volume with respect to design of WHRB 11 Ton steam
generation then holding capacity of economizer is more for 10 ton WHRB.
(d) Check Flue gas temperature at ESP Inlet.

As in the year 1993 waste heat boiler was made available in India only by BHEL at Prakash industries, Champa (C.G.) 32 Kg/Cm^2, at 400 Deg C.

Now technology has developed & we are getting from 100 TPD Klin of steam of 10 TPH, at 66 ata, at 485 Deg C from many Boiler manufacturer.

Today development have been made in 300 TPD klin & 500 TPD Klin in which Boiler manufacturer can produce steam at 105 Kg/Cm^2, at 490 Deg C. which is High pressure steam from WHRB coupled with CFBC for 30 MW to 50 MW will be more economical for Power Generation and sponge Iron Klin can generate power to boost the economy of the system.

New Concept of Waste Heat Steam Generation

Raipur Power Gen has developed a New concept of WHRB( Waste Heat Recovery Boiler) from sponge Iron Kiln.

In General Sponge Iron Kiln we have for example 100tpd( tones per day ) that generates 24,000 cum/hr hot gases at 950degC to be used for WHRB to produce steam of 10 tph (tones per hour ) , 64ata, 485degC with each boiler attached with 100 tpd Sponge Iron Kiln .
We know in this we would need 3 WHRB’s would be needed under 3 separate kiln.
In the new concept that RPG has developed we have combined 3X100 tpd sponge from Hot Gas duct in one WHRB (waste heat recovery boiler) having isolation slide gate (water cooled ) at inlet of hot duct on riser side.
This slide valve can withstand temperature upto 1600degC and by valve controlling we can control the pressure inside the kiln if necessary.

After combining all the three duct’s in one WHRB we can get waste gas of 3X24000cum/hr & corresponding steam generation 30 tph (tonne per hour) for running steam turbine generator. And now if one kiln is under shutdown we are providing pulverized coal nozzle to generate more gas vice versa we would get more steam from waste heat boiler. The coal nozzles and slide gates valves are imported.

The Operation of this kind of a project under my guidance will begin from JUNE 09.
For which boilers are under erecting stage.

The total design and concept has been verified by boiler design experts.
We sincerely and firmly believe and wish that we will achieve success in our developmental project and in future times this can be used with coal dust in plant for recycle.

D.Mukherjee
9827172172

Projects Handled

Indo-Lahari Power Ltd. Raipur (C.G.) - 6 MW BIOMASS (Rice Husk Based) , loan from IREDA, IDBI.
Vandana Vidyut Ltd, Bilaspur (C.G.)- 8 MW BIOMASS (Rice Husk Based) , loan IREDA.
Indsil Power Company Ltd.(C.G.) - 12 MW Coal Based
Drollia Electrosteels (P) Ltd (C.G.)- 12 MW Air Cooled Condenser Waste Heat Based
SKS Ispat Power (C.G.) - 25 MW Waste Heat Based
CHIND Power and Steel Pvt. Ltd. (C.G.)- 8 MW BIOMASS (Rice Husk Based) - Ongoing
G.R. Sponge and Power (P) Ltd.(C.G.) - 8 MW Air Cooled Condenser Waste Heat Based
Sunil Sponge (P) Ltd. Raipur (C.G.) - 8 MW Air Cooled Condenser Waste Heat Based - Equipment order placed - Ongoing
Aarti Sponge & Power (P) Ltd.(C.G.) - 10 MW Air Cooled Condenser Waste Heat Based - Equipment order placed - Ongoing
Devi Steel and Power Pvt. Ltd (C.G.) - 8 MW Air Cooled Condenser Waste Heat Based - Ongoing
Shyam Sponge and Power Pvt. Ltd (C.G.)- 20 MW Air Cooled Condenser Waste Heat Based - Ongoing
Mahaveer Energy and Coal Benefication Pvt. Ltd (C.G.) - 12 MW BIOMASS (Rice Husk Based) - Ongoing, on verge of completion
Kasturi Cements and Power Pvt. Ltd.(C.G.) - 30 MW Coal Based - Project initialized
Saikrupa Biotech Pvt. Ltd. (Andhra Pradesh) - 15 MW BIOMASS (Rice Husk Based) - Project initialized
N.R. Sponge Pvt. Ltd. (C.G.) - 12 MW Air Cooled Condenser Waste Heat Based - Ongoing
Bilasraika Sponge Iron India Pvt. Ltd. - 12 MW Air Cooled Condenser Waste Heat Based - Ongoing

Detailed Engineering Services (Synopsis)

Civil Engineering
Structural Analysis
Civil design Drawings
Bill of Quantities
Mechanical Engineering
Specification for Main Plant Equipment
Specification & design drgs for Balance of Plant Equipment
Piping Layout/ Stress Analysis/ Bill of Quantities
Fabrication Drawings
Electrical Engineering
Specification & design drgs for Electrical Systems and equipment
Cable Routing, Cable Schedule and Bill of Quantities
Grounding Layout and Bill of Quantities
Instrumentation Engineering
Specification for Instrumentation system and Equipment

Basic Engineering Services (Synopsis)

System Design & Main Plant Equipment
Plot Plan/ Layouts/ General Arrangement Drawings
P&ID/ PFD
Electrical Single Line Diagrams
Protection and Control Philosophy
Intrumentation System Design and Architecture