pinch technology: 기본 이론

Pinch Technology:

기본 이론

Identify Opportunities by Inspection

ProcessUnit

10 C

100 C

150 C

30 C

Steam Cooling Water

Feed Product

An opportunity for heat recovery

Stream A Stream B

Heat kW

ProcessUnit

10 C

100 C

150 C

30 C

Steam Cooling Water

Feed Product

Tem

pera

ture

C

Good Idea … or is it?

A

B

Tem

pera

ture

C

Heat kW

CoolingWater

Steam

A pity !A pity !

One part of the siteOne part of the site Another locationAnother location

ProcessUnit

10 C

100 C

150 C

30 C

Steam Cooling Water

Feed Product

Tem

pera

ture

C

Heat kW

Not a good idea any more?Not a good idea any more?

A good idea ?A good idea ?

C

D

B

A

Tem

pera

ture

C

But suppose we could have seen the entire picture !But suppose we could have seen the entire picture !

Better Approach

B

A

C

D

Especially

• On a large site• When we have different departments• No one person has all the knowledge• etc.

How can we avoid missing such opportunities?

Do we really need 2,040 kW of steam?

An Example

Heating and Cooling Duties

The hot composite curve

The cold composite curve

Energy Targets Ahead of Design!

The composite curves

PINCH

Qcmin=120 kW

QHmin=960kW

The composite curves show our target (minimum)

should be 960 kW of steam

We actually use 2040 kW

Why?

The closest approach between the compositecurves represents the "Pinch".

Divide the process at the Pinch

The feasibility of heat transfer

Therefore if we have ‘A’ kW of cross pinch heat transfer our utility consumption will be: Steam Q HMIN + A

Cooling Water QCMIN + A

In our example the X pinch heat transfer must be 1080kW

• Do not use hot utility below

• Do not recover process heat across

• Do not use cold utility above

Do not Transfer heat across the PinchDo not Transfer heat across the Pinch

Divide the process at the pinch

Pinch Design Principles

Design now achieves the target of 960 kW steam

Pinch Design

NEW

Design now achieves the target of 960 kW steam

Pinch Design

NEW

SMALLER EXCHANGERAND BOILER PLANT

SMALLEREXCHANGERAND COOLINGTOWER

NEW

SMALLER EXCHANGERAND BOILER PLANT

SMALLEREXCHANGERAND COOLINGTOWER

Which Design Is Cheaper?

To operate - clearly the one with less energyTo build?

The more energy efficient design is not necessarily more expensive

Original Design

Q Q HOTHOT

Q Q HOTHOT

TT

HH

Q Q COLDCOLD

TT

HHQ Q COLDCOLD

Composite Curve Grand Composite Curve

Process / Utility Interface

TT

HH HH

HP SteamHP Steam

Cooling WaterCooling Water

HP SteamHP Steam

MPMP

LPLP

bfwbfwCWCW

Simple Process/UtilityInterface

Alternative Process/UtilityInterface

Process / Utility Interface