ENERGY CONSERVATION IN CHEMICAL PROCESS INDUSTRIES

1. ENERGY CONSERVATION IN CHEMICAL PROCESS INDUSTRIES Dr.V.SIVASUBRAMANIAN Associate Professor Former Head Chemical Engineering NIT Calicut

2. DEPARTMENT OF CHEMICAL ENGINEERING

3. Agenda • Introduction • Energy Conservation in Reactors • Energy Conservation in Packed Beds • Energy Conservation in Heat Exchangers • Energy Conservation in Evaporators • Energy Conservation in Crushers and Grinders • Heating and Cooling Requirement in Distillation Columns • Energy Conservation in Dryers • Energy Conservation in Pumps • Methodology of Optimizing Energy Use • Areas of energy Optimization in CPI • Energy Efficiency Improvement and Cost Saving Opportunities in Petrochemical Industry

4. 1. Introduction CHEMICAL PROCESS UNIT PROCESS UNIT OPERATION CHEMICAL ENGINEERING DEPT NIT CALICUT

5. Figure I Input – Processing – Output System • RECYCLE DISPOSAL WASTE INPUT OUTPUT PROCESSING CHEMICAL ENGINEERING DEPT NIT CALICUT

6. Chemical Reaction Types in Petrochemical Industries U.S.-EPA (1993)

7. Unit Operations • Liquid-vapor separation (distillation, evaporation, stripping) • Liquid-liquid separation (extraction, decanting) • Solid-liquid separation (centrifugal, filtration) • Solid-gas separation (filtration) • Solid-solid separation (screening, gravity) CHEMICAL ENGINEERING DEPT NIT CALICUT

8. 2.Energy Conservation in Reactors Ideal Reactors • Batch reactor, or BR (b) Plug flow reactor, or PFR and (c) Mixed flow reactor, or MFR

9. Broad Classification of Reactor Types (a) The batch reactor. (b) The steady-state flow reactor. (c), (d), and (e) Various forms of the semibatch reactor CHEMICAL ENGINEERING DEPT NIT CALICUT

10. Material Balance for the Element of Volume of Reactor

11. Material Balance for the Element of Volume of Reactor

12. Energy Balance for the Element of Volume of Reactor

13. Energy Balance for the Element of Volume of Reactor

14. AGITATION PROCESS VESSEL

15. Mixing Impellers • (a) three-blade marine propeller; (b) open straight-blade turbine; (c) bladed disk turbine; (d) vertical curved-blade turbine; (e) pitched-blade turbine

16. Design of Agitated Vessel

18. Power Consumption in Agitated Vessel • Np power no. • P power in kW • gc Newton’s law proportionality factor • n rotational speed r/s • Da diameter of impeller in m •  density in kg/m3

19. Power Correlation • S1, S2, Sn – Shape factors • hc individual htc for outside of coil, W/m2-C • Dc outside dia of coil tubing, m • k thermal conductivity, W/m-C • Cp specific heat @constant pressure, J/g-C •  absolute viscosity, cP • w absolute viscosity @wall or surface temp

20. Swirling flow pattern with a radial-flow turbine in an unbaffled vessel

21. Prevention of Swirling

22. Multiple turbines in tall tanks

23. Draft tubes, baffled tank (a) Turbine (b) propeller

24. Energy Efficiency in Reactors Agitator motor current monitoring: VFD deployment –feasibility. Accurate mass transfer for reaction by mass flow meters or vortex/magnetic flow meters. Recovery of heat in case of Exothermic Reaction Batch –Automation to control the reaction within a narrow range, saving energy consumed.

25. 3. Energy Conservation in Packed Beds Nusselt Number hw individual htc of gas film near tube wall Dp diameter of particle kg thermal conductivity of gas Prandtl Number,

26. 4. Energy Conservation in Heat Exchangers Single pass tubular condenser

28. Energy Balance in Heat Exchangers flow rate of stream q = Q/t = rate of heat transfer into stream Ha, Hb enthalpies per unit mass of stream at entrance and exit

29. EXTENDED SURFACE EQUIPMENT Types of extended surface: (a) longitudinal fins; (b) transverse fins.

30. 5. Energy Conservation in Evaporators • Types of Evaporators

31. Climbing-film, long-tube vertical evaporator

32. Evaporator Capacity and Economy q rate of heat transfer through heating surface from steam Hs specific enthalpy of steam Hc specific enthalpy of condensate s latent heat of condensation of steam rate of flow of steam

33. Methods of Feeding in Evaporator • Patterns of liquor flow in multiple~effect evaporators: • (a) forward feed • (b) backward feed • (c) mixed feed • (d) parallel feed

34. 6. Energy Conservation in Crushers and Grinders • Rittinger’s Law • Kick’s Law • Bond’s Law

35. 7. Heating and Cooling Requirement in Distillation Column If saturated steam is used as the heating medium, the steam required at the reboiler steam consumption vapor rate from reboiler s latent heat of steam  molal latent heat of mixture

36. If water is used as the cooling medium in the condenser and the condensate is not subcooled, the cooling-water requirement is water consumption T2 - Tl = temperature rise of cooling water

37. 8. Energy Conservation in Dryers Tray Dryer

38. Temperature Patterns in Dryers • batch dryer • continuous countercurrent adiabatic dryer

39. Calculation of Heat Duty Heat transferred per unit mass of solid

40. 9.ENERGY CONSERVATION IN PUMPS

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