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ENERGY EFFICIENCY IMPROVEMENT in Refineries and Petrochemical Plants. Unit Operations in Process Plants. Distillation / Evaporation Heat Transfer Pumping and Compression Filtration / Crystallisation Chemical reaction processes. Energy Minimisation in Distillation.
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ENERGY EFFICIENCY IMPROVEMENT in Refineries and Petrochemical Plants
Unit Operations in Process Plants • Distillation / Evaporation • Heat Transfer • Pumping and Compression • Filtration / Crystallisation • Chemical reaction processes
Energy Minimisation in Distillation • Typically distillation is a maximum energy consuming unit operation deployed in Refineries and Petrochemicals • Energy Requirement : 40 – 60 % of the total Energy
Energy Minimisation in Distillation • Distillation at low pressure • Maximizing Pump Arounds in Petroleum type distillation • Compensating seperation with increased no of stages as Pump Arounds will reduce internal reflux • Drawing products/Pump Arounds at maximum temperature for preheating feed/utilities. • Optimisation of Stripping steam / overflash
Energy Minimisation in Distillation Overhead Heat Integration GAS FEED Preferred for super fractionators and also in crude distillation
Energy Minimisation in Distillation Conventional Process GAS FEED Example:-1 Butene Separation process
Energy Minimisation in Distillation Heat Coupled Process FEED Example:-1 Butene Separation through Heat Coupled Process
Energy Minimisation in Distillation Heat Coupling in Distillation GAS FEED Example:-In super fractionator or distillation column operating with high R/R, above type of Heat coupling is beneficial
Energy Minimisation in Distillation Multiple Heat Coupling GAS REB-1 REB-3 REB-2 Example:- Xylene Column of Px Plant
Energy Minimisation in Distillation Vapour Compression in Distillation GAS
Energy Minimisation in Distillation Vapour Compression in Distillation FEED
Energy Minimisation in Distillation Vapour Compression in Distillation
Energy Minimisation in Distillation Vapour Compression in Distillation
Energy Minimisation in Distillation Low Temp heat integration in Distillation column Conventional FEED Steam reboiler 190 C
Energy Minimisation in Distillation Low Temp heat integration in Distillation column To Crude Preheat Train FEED
Energy Minimisation in Crude/Vacuum Distillation • Overhead Integration • Maximisation Pump Arounds • Introduction of top PA • Use of Pretopper • Low column pressure • Avoid successive distillation and try to draw product from same distillation column.
Energy Minimisation Crude/Vacuum Distillation Top Pump Around crude integration Crude FEED PA’s are maximised to reduce R/R and seperation is compensated by higher nos of stages
Energy Minimisation in Hydrotreaters/ Hydrocrackers Conventional stripping of CLPS Stream GAS to LE Section CLPS LIQ STABILISER FRACTIONATOR
Energy Minimisation in Hydrotreaters/ Hydrocrackers Adding Stripper ahead of Main Fractionators GAS CLPS LIQ MP STRIPPER STEAM FRACTIONATOR • Eliminate WGC • Reduce reboil requirement for stabiliser/de-ethaneiser
Energy Minimisation in Hydrotreaters/ Hydrocrackers Addition of heat exchangers /steam generators in between successive reactors CLPS LIQ FEED RG HPS FRACTIONATOR
Energy Minimisation in Hydrotreaters/ Hydrocrackers • Even Steam Generators can be installed to recover heat of individual reactors • Utility generation in HP heater convection to increase efficiency of HP furnaces
Energy Minimisation in Hydrotreaters/ Hydrocrackers CHPS/HHPS CLPS/HLPS160 Kg/cm2gPressure RT Cascaded with drives of feed pump to provide around 30% pump power drive 25 kg/cm2g HHPS/CHPS HLPS/CLPS PRT
Energy Minimisation in Hydrotreaters/ Hydrocrackers CONVENTIONAL DESIGN GAS Rx EFFLUENT RGC 55 – 60 C AIR COOLER CHPS WASH WATER HEATER FRACTIONATOR CLPS
Energy Minimisation in Hydrotreaters/ Hydrocrackers Use of HHPS to conserve heat instead of CHPS MODIFIED ENERGY EFFICIENT DESIGN R GAS RGC 55 – 60 C Rx EFFLUENT AIR COOLER CHPS WASH WATER ~180 C HHPS CLPS ~180 C HLPS FRACTIONATOR
Energy Minimisation Refinery Very Low Temp heat integration • Hot products are cooled by tempered water coolers and the tempered water is cooling with heating of DM Water before feeding to Deaerators • Overall pinch to improve plant efficiency / Grand composite
Energy Minimisation in Coker • Efficient integration of feed preheat circuit • Maximisation of Hot feed streams • Recovery of Blowdown tower off gases
Energy Minimisation in FCCU • Maximize Main Column Bottom Pump Around to heat feed /raise BFW • PRT for air blower ---Regen. Flue Gas PRT provides part of power to drive main air blower • Two stage regeneration --- First stage: 2C+O2=2CO CO incinerator --- Second stage:2CO+O2=2CO2 • Feed Preheat improvement
Energy Minimisation in other processes • Separation done through Molecular Sieve or Membrane separation technology as a substitute of distillation/extraction -- ISOSIV for separation of iso-paraffins from normals -- PSA for H2 separation from Syn Gas -- Molex Process- for ext of n-paraffin for LAB prodn -- Parex Process- for ext of p-xylene for PX prodn • Supercritical extraction of Asphalts with propane • Introduction of Low Pressure Technologies
Energy Minimisation in Refinery General for Furnace Efficiency Improvement • Furnace Flue Gas temp lowering either with APH or outside/inside mounted steam generator • Excess Air Control • Steam Generation in HP Furnaces
Energy Minimisation in Refinery General for Heat Exchanger Efficiency Improvement • Use of packinox to low approach Heat Exchangers • Cleaning of Heat Exchangers periodically • Better thermal design with optimum velocities
Energy Minimisation in Refinery General Pumps & Compressors Efficiency Improvement • Minimise Recirculation / Spillback flows • Operate at the best efficiency point to the extent possible • Better specification of pumps / compressors during design stage for operation around best efficiency point. • Pressure cascading to avoid successive pumping and compression.
