1. Critical environment challenges and constraints of foundries and feasible clean technology options Workshop on Sustainable Environment Practices in Foundry Sector, Kolkata Prosanto Pal Senior Fellow, TERI, New Delhi prosanto@teri.res.in 24 August 2012

2. Outline  About TERI  Cleaner technology demonstrations in the foundry sector and TERI’s work  Environment challenges and way forward

3. Origins of TERI  Conceived by Late Sri Darbari Sethi of Tata Chemicals  Registered as ‘Tata Energy Research Institute’ in 1974  1974-82 – operated from Mumbai  Moved to Delhi in 1982  Own premises at India Habitat Centre in 1994

4. Research orientation  Independent, non-profit, research institute  Core competencies – research, information & communication and training & outreach  Undertakes sponsored research projects in energy, environment and sustainable development areas  Major sponsors include GOI, corporate, multilateral & bilateral agencies

5. Salient features of gray iron foundries  Cupola is common melting furnace  Conventional cupolas poorly designed and operated leading to high coke consumption  No standardized design of pollution control system to control suspended particulate matter (SPM) Commissioning of the demonstration plant

6. Present technology status  Cupola –Poor furnace design –Poor operating practices –Non-uniform size of charge material  PCS –Variety of PCS designs –Short life/high corrosion –Poor knowledge on emission standards and PCS technology

7. Pollution reduction at source by Energy Efficient Cupola  Divided blast cupola –Reduces coke consumption by about 25% –Increases tapping temperature by about 50º C –Increases melting rate  Best operating practice –optimization of blast rate –bed preparation –sizing the raw material –charging practices

8. CPCB emission standards TypePollutantConc. (mg/Nm 3 ) Cupola < 3 tph > 3 tph Particulate 450 150 Induction furnacesParticulate150 SO 2 – 300 mg/Nm 3

9. UK emission standards TypePollutantConc. (mg/Nm 3 ) New cupola Particulate20 Existing cupola Less than 4 tph 4 tph and more Particulate No standard 100

10. SPM emissions from cupola without PCS (1300-2200 mg/Nm 3 ) Figure 3

11. Common PCS types Minimum Particle size, μm Collection efficiency, % Cyclone> 10< 85 Multiple cyclone> 5< 95 Wet cap> 5< 95 Venturi-scrubber> 0.5< 99 Fabric filter> 0.2< 99

12. Selection criteria of PCS  Fines in cupola emissions is high (< 5 μm 16%)  Ability to meet the 150 mg/Nm3 norm  Life of the equipment  Ability to control SO2 emissions

13. Different PCS initiatives in Howrah  CPCB-NML ‘cyclone’ system at M/s Crawley & Ray  NML-IFA cyclone system at M/s Shree Uma Foundries (P) Ltd, Liluah  B.E. College-WBPCB ‘wet scrubber’ at M/s Bharat Engineering Works  Jadavpur-HFA ‘cyclone and submerged wet-scrubber’ system  TERI-SDC ‘venturi-scrubber’ system at M/s Bharat Engineering Works

14. Spark arrestor/ dry arrestor/Chinese hat type (Coimbatore)

15. Wet-scrubber system (PCST) DIRTY FLUE GAS WATER AND ENTRAINED DUST TO SETTLING TANK WATER FILM WATER CUPOLA CANOPY DEFLECTOR

16. Photo of wet cap

17. Three stage wet-scrubber system (B.E.- WBPCB)

18. Cyclone & submerged wet-scrubber system Cupola  conventional cyclone  high efficiency cyclone  submerged wet scrubber  ID fan

19. Twin cyclone

20. Demonstration Plant at Bharat Engineering Works, Howrah Commissioned 1998 DBC – Divided Blast Cupola Bucket charging system PCS – Pollution Control System (venturi-scrubber) 100 ft free standing chimney TERI-SDC demonstration plant

21. Demonstration plant

22. Salient features of the TERI-SDC design  Divided blast cupola –matching molten metal requirement to cupola size –increase stack height to utilize heat in flue gas –proper selection of cupola blower –proper distribution of blast air –feedstock weighted & charged mechanically  Venturi scrubber system –fitted with variable throat –critical surfaces made of stainless steel –gas tight construction with explosion doors

23. Photos of PCS

24. Coke charge in CC 13.6% Coke charge in DBC 8.8 % Energy savings 35 % [(13.6 – 8.8)/13.6] Energy performance

25. Figure 4

26. Stainless Steel Venturi Scrubber

27. Environment performance

28. (a) without PCS: 2000 mg/Nm 3 (b) with common PCS: 500 mg/Nm 3 (c) with venturi scrubber: 50 mg/Nm 3

29. Environmental challenges  High cost of pollution control especially for small foundry units  Pollution control cost is same for small and large foundries  Particle size analysis is most important in selection of pollution control system  Can be done using centrifugal dust classifier or image analyzer (more accurate)  Fine particles get deposited in filter paper

30. Environmental challenges  Problems in isokinetic sampling : accuracy of stack velocity measurement  At no time the gas pressure at sampling point should be negative  Lowest pressure level which can be accurately measured in field conductions is about 3 m/s  If ratio of highest to lowest pitot-static reading exceeds 9:1 (ratio of highest to lowest gas velocity exceeds 3:1) new sampling position needs to be sought  Repeat the readings of gas velocity and temperature  If the sum of pitot static readings differ by more than 10% (or sum of gas velocity readings by more than 5%) the test is not accurate  Measurement of emission level using instrument based on light extinction principle (using laser light) is better

31. Way-forward  Adopt energy efficient DBC for all new cupola  Develop clearer guidelines for selection of PCS  Appoint independent agency to validate design, fabrication and installation  Develop approved list of vendors/fabricators for fabricating/ installing PCS  Provide soft loans for PCS  Hold regular training programs on stack monitoring and PCS design/operation for PCB staff, fabricators and entrepreneurs

32. Thank you for your kind attention!