Inst ToolsInst ToolsInst Tools
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Search
  • Books
  • Software
  • Projects
  • Process
  • Tools
  • Basics
  • Formula
  • Power Plant
  • Root Cause Analysis
  • Electrical Basics
  • Animation
  • Standards
  • 4-20 mA Course
  • Siemens PLC Course
Reading: Three Element Drum Level Control System
Share
Font ResizerAa
Inst ToolsInst Tools
Font ResizerAa
  • Courses
  • Design
  • PLC
  • Interview
  • Control System
Search
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > Control Systems > Three Element Drum Level Control System

Three Element Drum Level Control System

Last updated: May 4, 2019 5:47 pm
Editorial Staff
Control Systems
2 Comments
Share
4 Min Read
SHARE

In most drum level control applications, the two-element drum level control will maintain the required water/steam interface level – even under moderate load changes.

However, If an unstable feedwater system exists exhibiting a variable feed header-to-drum pressure differential, or if large unpredictable steam demands are frequent, a three-element drum level control scheme should be considered. As implied from the previous information, this control strategy supplies control of feedwater flow in relationship to steam flow.

The performance of the three-element control system during transient conditions makes it very useful for general industrial and utility boiler applications. It handles loads exhibiting wide and rapid rates of change. Plants which exhibit load characteristics of this type are those with mixed, continuous, and batch processing demands. It is also recommended where normal load characteristics are fairly steady; but upsets can be sudden, unpredictable and/or a significant portion of the load.

How it works:

The Below Figure shows the control scheme for three-element drum level control. To the left of the dotted line, the instrumentation is the same as that for the two-element drum level control, with one exception: the output of the feedwater flow computer now becomes the set-point of the feedwater flow controller (FIC-2). Equipment required to complete our three-element drum level control scheme includes an additional flow device (FE-2) and differential pressure transmitter (FT-2).

Three Element Drum Level Control SystemThe area to the left of the dotted line in figure functions the same as that of a two-element drum level control. We can pick up the operation for this scheme where the output signal of the feedwater flow computer (the combination of steam flow and drum level) enters the feedwater controller (FIC-2).

This in effect becomes the set-point to this controller. Feedwater flow Is measured by the transmitter (FT-2). The output signal of the feedwater flow transmitter is linearized by the square root extractor, (FY-2) (Note: Now a days square root extractor function provided in either transmitter or controller as inbuilt option). This signal is the process variable to the feedwater controller and is compared to the output of the feedwater flow computer (set-point). The feedwater flow controller produces the necessary corrective signal to maintain feedwater flow at its set-point by the adjustment of the feedwater control valve (FCV-1).

As in the two-element drum level control scheme, nearly all of the work necessary to compensate for load change is done by the feed-forward system (i.e. a pound of feedwater change is made for every pound of steam flow change). The drum level portion of the control scheme is used only in a compensating role. Despite low-to-moderate volume/ throughput ratio and a wide operating range, it is expected the drum level will be maintained very close to set-point. Achieving this requires use of the integrating response and reset in both the drum level and feedwater controllers.

Source : ABB

Don't Miss Our Updates
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Invalid email address
You've successfully subscribed !

Continue Reading

Control Room Design Guidelines
Industrial Automation in the Mining Industry
Chemical Reactor Temperature Control System
What is High Integrity Pressure Protection System?
Introduction to Control System
Liquid Level Switch Control Pump and Lamp
Share This Article
Facebook Whatsapp Whatsapp LinkedIn Copy Link
Share
2 Comments
  • Rodolfo Redovan says:
    March 27, 2017 at 3:05 pm

    How to prevent carry over on the steam boiler main header?

    Reply
  • Qadir Mohtasham says:
    July 13, 2018 at 1:12 pm

    Good job

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Stay Connected

128.3kFollowersLike
69.1kFollowersFollow
210kSubscribersSubscribe
38kFollowersFollow

Categories

Explore More

What is the OPC Server?
Proportional-only Control Theory
Basics of Wellhead Control Panel (WHCP)
Difference Between PNP and NPN Sensors
What is Maintenance Override Switch (MOS) ?
Control Modes of Air Handling Unit (AHU) – HVAC Basics
Anti Surge Controller Working Principle
Basics of Process Control Systems

Keep Learning

Rotary UPS or Dynamic UPS

What are Static UPS and Rotary UPS?

Basic Process Control System

Basic Process Control System

Identify Instruments in Piping and instrumentation Diagram

Identify Instruments in Piping and instrumentation Diagram

control of temperature in a vessel

How to Analyze PID Controller Actions

Levels in Industrial Automation

Five Levels in Industrial Automation

Fixed Type Motor control center (MCC)

Motor Control Center (MCC) Signal Interface Termination (SIT)

What is Open Telemetry?

What is Open Telemetry? – Principles and Benefits

EcoStruxure Machine Expert - HVAC - Programming Software

How to Write a Program in Ecostruxure Machine Expert HVAC Software?

Learn More

What is Travel Stop in Control Valve

What is Travel Stop in Control Valve?

Transmitter Range and Sensor Limits

Transmitter Minimum Span, Accuracy & Turndown

Gauge Display Scale

How to Read Gauge Analog Scales

How do AC drives work

How do AC Drives Work? – Variable Frequency Drive (VFD)

Industrial Control Systems Security

Comparing ICS and IT Systems Security

Safety PLC Programming steps

Safety Door Interlock PLC Program

Instrument Technician Interview Questions

Instrument Technician Interview Questions and Answers

Power Systems Questions & Answers

Power Systems MCQ Series 10

Menu

  • About
  • Privacy Policy
  • Copyright

Quick Links

  • Learn PLC
  • Helping Hand
  • Part Time Job

YouTube Subscribe

Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Welcome Back!

Sign in to your account

Username or Email Address
Password

Lost your password?