System for optimizing total air flow in coal-fired boilers
First Claim
1. A method of using a computer to monitor combustion of fuel to heat a fluid in a boiler, said method comprising the steps of:
- (a) detecting characteristics of the fuel supplied;
(b) measuring physical properties of the apparatus, by performing the following substeps;
(b2) measuring flow, temperature and pressure of the fluid in the boiler; and
(b2) detecting stack gas temperature; and
(c) determining an air/fuel mixture resulting in at least one of minimal heat loss and maximum production, while meeting operational criteria, said determining including the following substeps;
(c1) measuring rates of air and fuel supplied;
(c2) comparing the flow, temperature and pressure measured in step (b1) with a desired steam output; and
(c3) determining the air/fuel mixture for optimized operation, including the factors of(c3i) minimizing heat loss in the stack gases; and
(c3ii) preventing deterioration of the boiler while maintaining the desired steam output.
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Accused Products
Abstract
A system for monitoring combustion of coal in a boiler detects coal composition and heating value using a bulk material analyzer and determines an air/fuel mixture so that when the coal is burned oxygen is available throughout the boiler and the wall temperature of the boiler is maintained below the metallurgical limit and the surface temperature below the ash fusion temperature of the coal where slagging is not desired. The temperature and pressure of steam in the boiler, fuel and air flow rates and temperature and oxygen content of the stack gases are supplied to a boiler model. The boiler model predicts how varying the air supply rate affects sensible heat loss. Periodic measurements of unburned carbon in the ash produced by combustion of the coal are correlated with the operation of the boiler at the time that the ash was produced to provide a basis for estimating unburned coal loss. An optimum air/fuel mixture is determined to minimize heat loss for a given steam production rate or to maximize steam production, using the estimate of unburned carbon loss and output from the boiler model, while at all times maintaining sufficient air flow to prevent oxygen depletion and acceptable wall temperatures.
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Citations
12 Claims
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1. A method of using a computer to monitor combustion of fuel to heat a fluid in a boiler, said method comprising the steps of:
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(a) detecting characteristics of the fuel supplied; (b) measuring physical properties of the apparatus, by performing the following substeps; (b2) measuring flow, temperature and pressure of the fluid in the boiler; and (b2) detecting stack gas temperature; and (c) determining an air/fuel mixture resulting in at least one of minimal heat loss and maximum production, while meeting operational criteria, said determining including the following substeps; (c1) measuring rates of air and fuel supplied; (c2) comparing the flow, temperature and pressure measured in step (b1) with a desired steam output; and (c3) determining the air/fuel mixture for optimized operation, including the factors of (c3i) minimizing heat loss in the stack gases; and (c3ii) preventing deterioration of the boiler while maintaining the desired steam output. - View Dependent Claims (2, 3, 4, 5, 6, 12)
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7. A method of using a computer to monitor combustion of coal to heat a boiler and produce steam, stack gases and ash, comprising the steps of:
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(a) continuously analyzing at least samples of the coal, using a bulk material analyzer to determine coal composition, during supply thereof; (b) calculating a heating value of the coal in dependence upon aid analyzing; (c) determining desired operating conditions by selecting a mode of operation from among at least minimizing the heat loss in the stack gases for a given steam production rate and maximizing steam production; (d) measuring steam flow, temperature and pressure in the boiler, air and coal supply rates, wall and surface temperatures of the boiler and oxygen concentration in the stack gases; (e) modeling boiler performance in dependence upon the steam flow, temperature and pressure, the air and coal supply rates, the coal composition and the heating value of the coal to predict heat loss in the stack gases; (f) determining an air/fuel mixture capable of maintaining the desired operating conditions, in dependence upon said modeling in step (e), to prevent boiler tube deterioration due to deficient amounts of oxygen and high wall temperatures and ash deposition due to excessive surface temperature, for the mode of operation selected in step (c). - View Dependent Claims (8)
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9. A system for monitoring combustion of coal in a boiler, comprising:
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a bulk material analyzer for analyzing the coal as it is supplied to the boiler to determine coal composition, ash content and heating value of the coal; measurement means for measuring steam flow, temperature and pressure in the boiler, air and coal supply rates, wall temperature of the boiler and oxygen concentration in the stack gases; input means for inputting periodic measurements of unburned coal in ash produced by the combustion of the coal and a mode of operation selected from among at least a fixed steam production rate and maximum steam production; processing means for modeling boiler performance in dependence upon the steam flow, temperature and pressure, the air and coal supply rates, the coal composition and the heating value of the coal to determine heat loss in the stack gases, for estimating unburned carbon content in the ash between the periodic measurements and for determining an air/fuel mixture in dependence upon the mode of operation, the modeling of boiler performance and the estimating of unburned carbon content. - View Dependent Claims (10, 11)
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Specification