ENERGY EFFICIENCY IMPROVEMENT in Refineries and Petrochemical Plants.

ENERGY EFFICIENCY

IMPROVEMENTin

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


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


Overhead Heat Integration

GAS

FEED

Preferred for super fractionators and also in crude distillation

Conventional Process

GAS

FEED

Example:-1 Butene Separation process


Heat Coupled Process

Example:-1 Butene Separation through Heat Coupled Process


FEED

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


Multiple Heat Coupling

GAS

Example:- Xylene Column of Px Plant

REB-1

REB-3

REB-2


Vapour Compression in Distillation

GAS



FEED


Low Temp heat integration in Distillation column

Conventional

FEED


Steam reboiler

190 C

Low Temp heat integration in Distillation column

FEED


To Crude Preheat Train

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.

Top Pump Around crude integration

FEED

Energy Minimisation Crude/Vacuum Distillation

Crude

PA’s are maximised to reduce R/R and seperation is compensated by higher nos of stages

Conventional stripping of CLPS Stream

CLPS LIQ

Energy Minimisation in Hydrotreaters/ Hydrocrackers

FRACTIONATOR

GAS to LE Section

STABILISER

Adding Stripper ahead of Main Fractionators

CLPS LIQ


STEAM

MP STRIPPER

FRACTIONATOR

Eliminate WGC

Reduce reboil requirement for stabiliser/de-ethaneiser

GAS

Addition of heat exchangers /steam generators in between successive reactors

FRACTIONATOR


HPS

CLPS LIQ

FEED RG


Even Steam Generators can be installed to recover heat of individual reactors

Utility generation in HP heater convection to increase efficiency of HP furnaces

CHPS/HHPS CLPS/HLPS 160 Kg/cm2g

Pressure RT Cascaded with drives of feed pump to provide around 30% pump power drive


PRT

HHPS/CHPS HLPS/CLPS

25 kg/cm2g

WASH WATER

GAS

CONVENTIONAL DESIGN

CHPS

55 – 60 C

RxEFFLUENT

AIR COOLER

RGC


HEATER

FRACTIONATOR

CLPS

Use of HHPS to conserve heat instead of CHPS

WASH WATER

R GAS

CHPS

55 – 60 CRxEFFLUENT

AIR COOLER

RGC

MODIFIED ENERGY EFFICIENT DESIGN


~180 C HHPS

HLPS

~180 C

FRACTIONATOR

CLPS

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 Refinery

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

Furnace Flue Gas temp lowering either with APH or outside/inside mounted steam generator

Excess Air Control

Steam Generation in HP Furnaces

General for Furnace Efficiency Improvement


Use of packinox to low approach Heat Exchangers

Cleaning of Heat Exchangers periodically

Better thermal design with optimum velocities

General for Heat Exchanger 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.

General Pumps & Compressors Efficiency Improvement

Thank You

ENERGY EFFICIENCY IMPROVEMENT in Refineries and Petrochemical Plants.

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