Emerson Compressor Control Process Control Made Easy with - - PowerPoint PPT Presentation

Emerson Compressor Control

Process Control Made Easy with SmartProcess™ Compressor

Agenda

Problems to Solve Compressor Control from Bottom to Top SmartProcess™ Compressor Additional Information

Problems to Solve

Compressor Operating Objectives

Operate Safely Avoid Compressor Surge Keep Compressor On-line Highest Possible Efficiency Automatically follow procedures to safely start, operate and shut down the compressor A surge event can damage the compressor and raise the potential for catastrophic consequences Handle process demand swings and avoid trips from hitting limits. Quickly troubleshoot and return to service when something happens Do not recycle already compressed gas Reduce Cost of Ownership Get rid of “black boxes” that require third party contractor to support

Compressor Operating Challenges

Basic Compressor Control Poorly Performing Control

Speed Of Response

Parallel and Serial Operation Manual operation and significantly reduced operating range and compression ratio Profit loss due to inefficiencies: reduced operating range, higher compression ratios unavailable Potential for surging Surge events require very high scan rate to efficiently prevent instability Lack of recorded data Control loops interaction, inefficiency, potential for surging Black Box Problem Highly-specialized hardware, software and expertise

Compressor Control

From Bottom to Top

What is surge?

Flow Rc

Pd Rc Ps

~

Vol 2 Vol 1 PLoad

What is surge?

Flow Rc

Pd Rc Ps

• Motor started, compressor unloaded

~

Vol 2 Vol 1 PLoad

What is surge?

Flow Rc

• Antisurge valve is closing
• Discharge pressure is raising

Pd Rc Ps

~

Vol 2 Vol 1 PLoad

What is surge?

Flow Rc

• Antisurge valve is closing
• Discharge pressure is raising

Pd Rc Ps

~

Vol 2 Vol 1

• Check valve opens

PLoad

What is surge?

Flow Rc

Pd Rc

• Compressor reaches surge point A
• Max RC and Min Flow cause rotating stall
• Compressor surges
• PLoad becomes bigger than Рd

Surge Line Ps A

~

Vol 2 Vol 1 PLoad

What is surge?

Flow Rc

• Reverse flow
• Operating Point reaches point B
• Check valve closes
• Flow drops from А to В within 20-60 ms

Pd Rc B Surge Line Ps A

~

Vol 2 Vol 1 PLoad

What is surge?

Flow Rc

• Reverse flow makes RC drop
• Operating Point reaches point C
• Transition from B to C is 200 to 1000 ms

Pd Rc B C Surge Line Ps A

~

Vol 2 Vol 1 PLoad

What is surge?

Flow Rc

• Compressor can maintain the RC
• Operating Point reaches point D
• Check valve opens

Pd Rc B C Surge Line Ps A D

~

Vol 2 Vol 1 PLoad

What is surge?

Surge phenomena applies to only centrifugal and axial compressors.

• From A to B (surge): 20 ÷ 60 ms
• From C to D (recovering): 20 ÷ 120 ms
• A-B-C-D-A (full surge cycle): 0,4 ÷ 2,0 sec

Flow Rc

Pd Rc B C Surge Line Ps A D

~

Vol 2 Vol 1 PLoad

Antisurge Control: Key Elements

Nmax Nmin Operating Point

1 2

P dPo q = % 100

2 2

 =

SL OP

q q OP

2 1 2 1

ln = ln T T P P             





1 − =

c p

R h

red

( )

red

p

h f q =

Key Antisurge Control Features

• Calculate Operating Point value
• Main PI control loop
• Derivative Control
• Open-loop step response
• Limiting Loops
• Adaptive tuning parameters
• Automated load/unload/ESD/purge

Basic Antisurge Control Strategy

Calculation

• f the OP

and other parameters Flow Pressure Temperature PID Control Safety Open Step Loop Decoupling Input

>

Manual Operation and Automatic Sequencing Output to the Antisurge Valve Antisurge Valve Balancing Input Valve After Surge Loop Decoupling Output Antisurge Valve Balancing Output

Load Control: Key Elements

Key Load Control Features

• Main PI control loop
• Limiting Loops
• Automated load/unload/ESD/purge

Surge line Choke

РТ N1 N2 N3

Pressure limit Power limit Pressure setpoint Network (process) resistance

Pressure ratio Flow

1

Power Flow

N1 N2 N3

Recycle

2 3

Savings

Load Sharing: Key Elements

Key Load Sharing Features

• Optimized overall efficiency
• Operating Points reach control

lines simultaneously

• Antisurge Valve Balancing
• Automated load/unload
• No Master Controller – no single

point of failure

Single Compressor

• Most of the time it looks like this:

Main Control Parameter Anti-Surge Valve Load Control

Parallel Compressors

• Or like this:

Main Control Parameter Anti-Surge Valve Load Control

Parallel and Serial Compressors

• Or like this:

SmartProcess™ Compressor

DeltaV Controls

Emerson SmartProcess™ Compressor Solution

Experts Smart Devices Pre-Engineered Module Libraries Special Anti-Surge Valves

Emerson SmartProcess™ Compressor Solution

• Pre-engineered DeltaV compressor control libraries
• Standard DeltaV graphical objects
• Fast Historian software
• Compressor control expertise
• Customer training
• Worldwide engineering centers
• Global support

Main Control Functions

• SmartProcess™ Compressor

DeltaV Control libraries:

– Antisurge Control – Load Control – Load Sharing Control – Automatic load, unload, ESD and purge sequencing – Demo system simulator

• Documentation

Example Screen from Real Project

DeltaV Template Libraries

• Standard template libraries
• Sample graphics
• Custom faceplates
• Documentation

– Installation Manual – Configuration Guide – User Guide

Fast Data Recording

Fast Data Recording

Compressor Consulting Services

• Project Services

– FEED – Control Strategy Consulting – Instrumentation and Control Performance Review – Configuration – Commissioning

• Global Worldwide Support
• On-site troubleshooting and Support

– Surge testing – Tuning and modifications assistance

Compressor Controls Engineers

SmartProcess™ Compressor Benefits

• No black boxes
• High-quality Antisurge Control
• Increased efficiency
• Standard solution supported worldwide

Additional Information

• SmartProcess™ Compressor Product Data Sheet

– Web Link: http://www.emerson.com/documents/automation/1510338.pdf

• Emerson Turbo Machinery Control Solutions Brochure

– Web Link: http://www.emerson.com/documents/automation/587900.pdf