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Title: Ash level meter for a fixed-bed coal gasifier

An ash level meter for a fixed-bed coal gasifier is provided which utilizes the known ash level temperature profile to monitor the ash bed level. A bed stirrer which travels up and down through the extent of the bed ash level is modified by installing thermocouples to measure the bed temperature as the stirrer travels through the stirring cycle. The temperature measurement signals are transmitted to an electronic signal process system by an FM/FM telemetry system. The processing system uses the temperature signals together with an analog stirrer position signal, taken from a position transducer disposed to measure the stirrer position to compute the vertical location of the ash zone upper boundary. The circuit determines the fraction of each total stirrer cycle time the stirrer-derived bed temperature is below a selected set point, multiplies this fraction by the average stirrer signal level, multiplies this result by an appropriate constant and adds another constant such that a 1 to 5 volt signal from the processor corresponds to a 0 to 30 inch span of the ash upper boundary level. Three individual counters in the processor store clock counts that are representative of: (1) the time the stirrer temperature is below themore » set point (500.degree. F.), (2) the time duration of the corresponding stirrer travel cycle, and (3) the corresponding average stirrer vertical position. The inputs to all three counters are disconnected during any period that the stirrer is stopped, eliminating corruption of the measurement by stirrer stoppage.« less
Authors:
 [1]
  1. (Morgantown, WV)
Publication Date:
OSTI Identifier:
865138
Report Number(s):
US 4466747
Resource Type:
Patent
Research Org:
National Energy Technology Laboratory, Pittsburgh, PA, and Morgantown, WV
Country of Publication:
United States
Language:
English
Subject:
ash; level; meter; fixed-bed; coal; gasifier; provided; utilizes; temperature; profile; monitor; bed; stirrer; travels; extent; modified; installing; thermocouples; measure; stirring; cycle; measurement; signals; transmitted; electronic; signal; process; fm; telemetry; processing; analog; position; transducer; disposed; compute; vertical; location; zone; upper; boundary; circuit; determines; fraction; total; time; stirrer-derived; below; selected; set; multiplies; average; result; appropriate; constant; adds; volt; processor; corresponds; 30; inch; span; individual; counters; store; clock; counts; representative; 500; degree; duration; corresponding; travel; inputs; disconnected; period; stopped; eliminating; corruption; stoppage; signal level; bed temperature; fixed-bed coal; measurement signals; temperature profile; bed level; coal gasifier; coal gas; time duration; ash bed; bed coal; temperature measurement; vertical position; ash level; electronic signal; circuit determines; temperature signal; level meter; position signal; signal process; cycle time; vertical location; measurement signal; temperature measure; bed stirrer; /374/48/73/