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Title: Air-flow regulation system for a coal gasifier

Abstract

An improved air-flow regulator for a fixed-bed coal gasifier is provided which allows close air-flow regulation from a compressor source even though the pressure variations are too rapid for a single primary control loop to respond. The improved system includes a primary controller to control a valve in the main (large) air supply line to regulate large slow changes in flow. A secondary controller is used to control a smaller, faster acting valve in a secondary (small) air supply line parallel to the main line valve to regulate rapid cyclic deviations in air flow. A low-pass filter with a time constant of from 20 to 50 seconds couples the output of the secondary controller to the input of the primary controller so that the primary controller only responds to slow changes in the air-flow rate, the faster, cyclic deviations in flow rate sensed and corrected by the secondary controller loop do not reach the primary controller due to the high frequency rejection provided by the filter. This control arrangement provides at least a factor of 5 improvement in air-flow regulation for a coal gasifier in which air is supplied by a reciprocating compressor through a surge tank.

Inventors:
 [1]
  1. Morgantown, WV
Issue Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States)
OSTI Identifier:
865042
Patent Number(s):
4453948
Assignee:
United States of America as represented by United States (Washington, DC)
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
air-flow; regulation; coal; gasifier; improved; regulator; fixed-bed; provided; allows; close; compressor; source; pressure; variations; rapid; single; primary; control; loop; respond; controller; valve; main; air; supply; line; regulate; slow; changes; flow; secondary; faster; acting; parallel; cyclic; deviations; low-pass; filter; time; constant; 20; 50; couples; output; input; responds; rate; sensed; corrected; reach; due; frequency; rejection; arrangement; provides; factor; improvement; supplied; reciprocating; surge; tank; acting valve; fixed-bed coal; line parallel; control arrangement; control loop; arrangement provides; coal gasifier; flow rate; air flow; coal gas; supply line; bed coal; air supply; time constant; pass filter; reciprocating compressor; air-flow regulation; low-pass filter; pressure variations; flow regulator; /48/137/

Citation Formats

Fasching, George E. Air-flow regulation system for a coal gasifier. United States: N. p., 1984. Web.
Fasching, George E. Air-flow regulation system for a coal gasifier. United States.
Fasching, George E. Sun . "Air-flow regulation system for a coal gasifier". United States. https://www.osti.gov/servlets/purl/865042.
@article{osti_865042,
title = {Air-flow regulation system for a coal gasifier},
author = {Fasching, George E},
abstractNote = {An improved air-flow regulator for a fixed-bed coal gasifier is provided which allows close air-flow regulation from a compressor source even though the pressure variations are too rapid for a single primary control loop to respond. The improved system includes a primary controller to control a valve in the main (large) air supply line to regulate large slow changes in flow. A secondary controller is used to control a smaller, faster acting valve in a secondary (small) air supply line parallel to the main line valve to regulate rapid cyclic deviations in air flow. A low-pass filter with a time constant of from 20 to 50 seconds couples the output of the secondary controller to the input of the primary controller so that the primary controller only responds to slow changes in the air-flow rate, the faster, cyclic deviations in flow rate sensed and corrected by the secondary controller loop do not reach the primary controller due to the high frequency rejection provided by the filter. This control arrangement provides at least a factor of 5 improvement in air-flow regulation for a coal gasifier in which air is supplied by a reciprocating compressor through a surge tank.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1984},
month = {1}
}

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