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Presentation outline

Company backgrounds

The IJmuiden site.

The need for pipeline management at IJmuiden.

The solution

Model predictive control

The solution so far Working together

Further work

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Gases

Healthcare ( medical )

Tonnage ( on-sites )

Merchant and packaged ( liquefied and cylinder gases )

Electronic gases

The Linde group

The Linde Group is one of the largest and most global of the world's leading gases and engineering

companies. Following the acquisition of BOC in 2006, we have 50,000 employees in more than 100

countries, and over 12 billion a year in sales.

Engineering

OlefinNatural gas

Air separation

Hydrogen and synthesis gas plants

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4500

Operations

Personnel

300

ASUs

70

HyCO

plants

100

CO2

plants

900

Ecovar

plants

350

Production

Sites

56

countries

Global Business Unit Tonnage: Global Operations

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Linde Global Operations ASU plants

Globally: 300 plants

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Linde Gas Global operations

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Tata Steel

In 2007 Tata Steel Limited acquired Corus Group plc

On 27 September 2010 Corus rebranded to Tata Steel

Tata Steel Group:

Fortune 500 company

Top 10 global steel producer

Annual crude steel capacity of 28 million tonnes

More than 80,000 employees

Manufacturing operations in 26 countriesacross 5 continents

Serving customers all across the globe

Turnover 2009-10: $22.8 billion

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Strip Products Mainland Europe & IJmuiden site (TataSteel)

Produces hot rolled steel strip, cold rolled, metallic coated

steels and processed steel products for industrial

applications (for example, for construction)

Manufacturing locations in different European countries.Largest production location in IJmuiden (9.300 employees)

Annual crude steel capacity of 7,5 million tonnes

Crude steel made by combination of 2 blast furnaces and

3- converter BOS plant Blast furnaces operate with high coal and O2 injection

rates

IJmuiden

Raw materials - Pig iron - Steelmaking - Casting - Rolling - Coating

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IJmuiden site

Challenges

TATA steel looking for improved site operation

HPGOX demand is not constant but highly changing due to the batch making pattern of steel making.

HPGOX pipeline with limited buffer capacity

MPGOX is constant for the blast furnaces but can go up and down in steps. This also is a challenge.

Typical HPGOX pattern

resulting in high pipeline pressure changes

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The need for better pipeline management

Improvements necessary in two main areas

Reduction in venting. Production to meet demand.

Better setting of the loads of the three main plants LF33, LF41, LF51 to improve overall

efficiency.

For Tata Steel

Reduced energy bill therefore reduced costs.

More reliable and consistent operation.

For Linde

Meeting the customers needs.

Reduced operator input and thereby can concentrate on other tasks.

More reliable and consistent operation.

Site can be brought into ROC operation.

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Model predictive control solution

Tata Steel had already proven in simulation that model predictive control can give improvements

in pipeline control. Online advisory system for Linde operators.

Linde has significant experience with implementing online model predictive controllers on their

air separation and HYCO units.

Model predictive control was our solution.

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Simplified architecture of the pipeline

LF41

LF51

PIC

PIC

HPGOX

VAROX ( 1- FAST )

BASIC ( 3 - SLOW )

MPGOX ( 2 MEDIUM )

22 bar gas to converters

( variable demand,

frequent large changes )

8 bar gas to blast furnace

(flatter demand pattern,

changes less frequent)

LOX TO

STORAGE

LIN TO

STORAGE

Other MP streams

( Normally constant unless plant /

compression change )

Other HP streams

( Normally constant

unless plant / compression change )

LET-DOWN

FLOW

FI

MP VENT

FLOW

HP VENTFLOW

LOX TANK

LEVEL

LIN TANK

LEVEL

MPGOX pressure needs to be very stable and so

HP supplements all the time unless very low

demand from blast furnace.

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LF51 simplified controls

FIC

LICFIC

FIC

HP TURBINE

PIC

MAIN

EXCHANGER

FIC

ARGON

SYSTEM

HPGOX TO PIPELINE

FIC

LIN TO

STORAGE

1

FIC

1

LPGAN

FIC

AIR TO

PLANT

LIQUID EXPANDER

LP TURBINE

LIC

LOX TO

STORAGE

*

*

*

*

*

**

**

**

* Adjusted for VAROX or BASIC

** Adjusted for BASIC

HP

COL

LP

COL

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LF41 simplified controls

FIC

LICFIC

FIC

HP TURBINE

PIC

MAIN

EXCHANGER

FIC

ARGON

SYSTEM

HPGOX TO PIPELINE

FIC

LIN TO

STORAGE

1

FIC

1

LPGAN

FIC

AIR TO

PLANT

LIQUID EXPANDER

LP TURBINE

LIC

LOX TO

STORAGE

*

*

*

*

*

**

**

**

* Adjusted for VAROX or BASIC

** Adjusted for BASIC

HP

COL

LP

COL

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Key handles.

Key handle Ramp speed Maximise or minimise

LF51 VAROX Minimal effect on

columns so can

move fast

Zero. Depends on how much LOX or LIN to produce.

Check tank levels.

LF51 BASIC Air change so

needs to be

slower

Maximise since LF51 BASIC can be produced

efficiently although high purity and high pressure

LF41 MPGOX No Argon so speed

can be medium

Minimise since LF41 oxygen is expensive to produce

although low purity.

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Model predictive control solution to work with existingsupervisory controls

Production Controller ( LMPC )

LF51 HPGOX

VAROX target

LF51 HPGOXbasic target

LF41 MPGOX

target

ALC LF51 ALC LF41

DCS LF51

PLANT SET-POINTS

E.G. HPGOX, AIR, REFLUX FLOWS; ETC.

DCS LF41

Plant set-points

E.G. HPGOX, AIR, REFLUX FLOWS; ETC.

EXISTING

NEW

LF41 and LF51 already have existing load control programs or automatic load change ( ALC ).

These give good performance within certain ramp speeds. The LMPC pipeline controller or

Production Controller was therefore interfaced with these existing load controllers.

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Variables in the model predictive controller

Type Description

MV

( manipulated )

LF51 VAROX target, LF51 BASIC target, LF41 MPGOX target

CV

( controlled )

VAROX target ( longer term requirement ). Note this is not actually a true CV but the

controller drives to it using a combination of LP weight.

LV

( constraint )

Let-down flow, HP pipeline pressure, LOX and LIN tank levels

FF

( feed-forward )

Demand forecast from Tata Steel ( still under test ).

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HPGOX demand forecast from customer

General expectation

Should be very useful for

ramping plants before the

actual demand changeoccurs

Key question

Quality of the forecast

Reliability of the signal

(data interface to

customer)

Demand picks up

before the

prediciton

Predicted time of

1hour with no

HPGOX demand

real demand

forecast (now)forecast (in past)

futurepastnow

Forecast given atthat time

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IJmuiden Production Controller: Control strategy

Use pipeline pressure as quickly reacting key measurement for demand changes.

Use LF51 VAROX and LF41 as quick control handles to control pressure within limits

Use LF51 base and LF41 to keep VAROX at target

On

Dropping pressure

(increased demand),ramping VAROX, LF41 andslowly LF51 base up

Slowly ramping LF51

base up, to be able to

keep VAROX at target

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Typical weekly performance: Production Controller

The Production Controller

significantly reduces venting that can be avoided

manages difficult situations without increase of controllable venting

On

High venting due to lack of MPGOX demand => high specific power

BUT: still very small controllable ventsHigh venting due to PC switched off(high controllable vents)

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IJmuiden Production Controller: First experience on site

What is observed so far

Significant reduction of GOX loss - benefit for customer Tata Steel

Reduction of specific norm power payments e.g. better balancing of ASUs for minimum

power - benefit for customer Tata Steel

Significant reduction of workload for the operator benefit for Linde

Operators do not have to permanently monitor changing customer demand of HPGOX and

MPGOX.

Production Controller automatically adapts production to meet varying customer demandand to minimise venting

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IJmuiden Production Controller: Novel features

Technology

Straight-forward LMPC solution at typical RTO layer.

In the LMPC solution, sensible approach to balance

short and long term objectives of the controller using LP weights.

People

Working closely with the customer ( Linde / Tata Steel ).

Working closely with the operators they like it !

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Further work

IMPROVE

Investigate further the use of demand forecast for improved oxygen pipeline control.

VAROX target at present operator set. Use longer term tools to advise e.g. steel works outage.

Replace ALC controllers on LF41/LF51 with LMPC for better control.

EXPAND

Inclusion of LF33 into the Production Controller once the LF33 control system has been upgraded.

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Any questions ?

The use of model predictive control foroxygen pipeline management.