L factor method for determining heat rate of a fossil fired system based on effluent flow

• US 6,560,563 B1
• Filed: 04/04/2001
• Issued: 05/06/2003
• Est. Priority Date: 03/24/1998
• Status: Expired due to Fees

• Current Assignee: Exergetic Systems LLC
• Original Assignee: Exergetic Systems LLC
• Inventors: Lang, Fred D.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Sun, Xiuqin
• Application Number:
  US09/827,956
• Time in Patent Office: 762 Days
• Field of Search: 702/182, 364/494, 364/498, 364/496, 454/192, 420/62, 651/34, 110/347, 110/191, 431/12, 162/198
• US Class Current: 702/182
• CPC Class Codes: F22B 35/18 Applications of computers to steam boiler control
• CPC Class Codes: F23N 2221/08 Preheating the air
• CPC Class Codes: F23N 2223/40 Simulation
• CPC Class Codes: F23N 2225/22 heat losses
• CPC Class Codes: F23N 5/003 using detectors sensitive to combustion gas properties F23N5/02, F23N5/18 - F23N5/26 take precedence

Abstract

The operation of a fossil-fueled thermal system is quantified by obtaining effluent flow, the L Factor and other operating parameters to determine and monitor the unit'"'"'s heat rate and to determine the emission rates of its pollutants.

Claims

1. A method for quantifying the operation of a fossil-fired system, the method comprising the steps of:

obtaining an L Factor;

determining a correction to the L Factor which converts its applicability from theoretical combustion to combustion associated with the fossil-fired system, and if applicable the correction for the system heating value base, and if applicable conversion to a wet-base L Factor;

combining the L Factor and the correction to the L Factor, resulting in a corrected L Factor;

obtaining a total effluents flow rate from the fossil-fired system;

obtaining a correction factor for the total effluents mass flow rate, resulting in a corrected total effluents mass flow rate; and

dividing the corrected total effluents flow rate by the corrected L Factor, resulting in a total fuel energy flow of the system.

2. The method of claim 1, wherein the step of obtaining the total effluents flow rate includes the steps of:

obtaining a total effluents volumetric flow rate from the fossil-fired system;

obtaining a density of the total effluents; and

obtaining the total effluents flow rate by multiplying the total effluents volumetric flow rate by the density of the total effluents.

3. The method of claim 1, including additional steps, after the step of dividing the corrected total effluents, of:

obtaining a produced electrical power from the fossil-fired system; and

dividing the total fuel energy flow of the system by the produced electrical power, resulting in a heat rate of the fossil-fired system.

4. The method of claim 1, including additional steps, after the step of dividing the corrected total effluents, of:

obtaining a fuel heating value of the fuel consumed by the fossil-fired system; and

dividing the total fuel energy flow of the system by the fuel heating value, resulting in a fuel flow rate of the fossil-fired system.

5. The method of claim 4, including additional steps, after the step of dividing the total fuel energy flow, of:

obtaining a turbine cycle energy flow;

obtaining a boiler efficiency;

obtaining a turbine cycle based fuel flow rate by dividing the turbine cycle energy flow by the product of the boiler efficiency and the fuel heating value; and

adjusting the turbine cycle energy flow until the turbine cycle based fuel flow rate and the fuel flow rate are in reasonable agreement.

6. The method of claim 1, including additional steps, after the step of dividing the corrected total effluents, of:

obtaining a fuel flow rate of the fossil-fired system; and

dividing the total fuel energy flow of the system, by the fuel flow rate, resulting in the fuel heating value of the fuel consumed by the fossil-fired system.

7. The method of claim 6, including additional steps, after the step of dividing the total fuel energy flow, of:

obtaining a turbine cycle energy flow;

obtaining a boiler efficiency;

obtaining a turbine cycle based fuel flow heating value by dividing the turbine cycle energy flow by the product of the boiler efficiency and the fuel flow rate; and

adjusting the turbine cycle energy flow until the turbine cycle based fuel heating value and the fuel heating value are in reasonable agreement.

8. The method of claim 1, wherein the step of determining the correction to the L Factor comprises the steps of:

obtaining a combustion air flow rate of the fossil-fired system by on-line monitoring;

obtaining a fuel flow rate of the fossil-fired system by on-line monitoring;

determining a correction for the system heating value base used by the fossil-fired system;

determining an on-line correction to the L Factor by combining the combustion air flow rate, the fuel flow rate and, if applicable, the correction for the system heating value base; and

obtaining a corrected L Factor by combining the L Factor and the on-line correction to the L Factor.

9. The method of claim 1, wherein the step of obtaining the L Factor, includes the step of:

determining that the fossil fuel is a coal;

determining a set of properties associated with the coal;

determining a rank for the coal from the set of properties, said rank to be either an anthracite coal, or a semi-anthracite coal, or a low volatile bituminous coal, or a medium volatile bituminous coal, or a high volatile A bituminous coal, or a high volatile B bituminous coal, or a high volatile C bituminous coal, or a sub-bituminous A coal, or a sub-bituminous B coal, or a sub-bituminous C coal, or a lignite A coal, or a lignite B coal;

depending on the rank of the coal, establishing the L Factor for the anthracite coal between 819.36 and 835.83 lbm/million-Btu, or establishing the L Factor for the semi-anthracite coal between 796.14 and 812.14 lbm/million-Btu, or establishing the L Factor for the low volatile bituminous coal between 784.97 and 800.75 lbm/million-Btu, or establishing the L Factor for the medium volatile bituminous coal between 778.81 and 794.47 lbm/million-Btu, or establishing the L Factor for the high volatile A bituminous coal between 774.19 and 789.75 lbm/million-Btu, or establishing the L Factor for the high volatile B bituminous coal between 775.33 and 790.91 lbm/million-Btu, or establishing the L Factor for the high volatile C bituminous coal between 776.82 and 792.43 lbm/million-Btu, or establishing the L Factor for the sub-bituminous A coal between 780.45 and 796.14 lbm/million-Btu, or establishing the L Factor for the sub-bituminous B coal between 779.28 and 794.94 lbm/million-Btu, or establishing the L Factor for the sub-bituminous C coal between 780.86 and 796.56 lbm/million-Btu, or establishing the L Factor for the lignite A coal between 788.63 and 804.49 lbm/million-Btu, or establishing the L Factor for the lignite B coal between 758.39 and 773.63 lbm/million-Btu.

10. The method of claim 1, wherein the step of obtaining the L Factor, includes the step of:

establishing a ratio of non-oxygen gases to oxygen used for ambient air conditions which is greater than a value of 3.7619 and less than a value of 3.7893.

11. The method of claim 1, wherein the step of obtaining the total effluents flow rate includes the step of:

obtaining a total effluents mass flow rate from the fossil-fired system.

12. The method of claim 1, wherein the step of determining the correction to the L Factor includes the steps of:

obtaining a ratio of actual dry-gas effluent mass flow to actual wet fuel mass flow;

obtaining a ratio of the ratio of the theoretical wet fuel mass flow to the theoretical dry-gas effluent mass flow; and

multiplying the ratio of actual dry-gas effluent mass flow to actual wet fuel mass flow by the ratio of the ratio of the theoretical wet fuel mass flow to the theoretical dry-gas effluent mass flow resulting in the correction to the L Factor.

13. The method of claim 1, wherein the step of determining the correction to the L Factor includes the steps of:

obtaining a ratio of actual dry-gas effluent volumetric flow to theoretical dry-gas effluent volumetric flow;

obtaining a ratio of the actual dry-gas density to the theoretical dry-gas density used to convert the ratio of actual dry-gas effluent volumetric flow to theoretical dry-gas effluent volumetric flow;

obtaining a ratio of the ratio of the theoretical wet fuel mass flow to the actual wet fuel mass flow; and

multiplying the ratio of actual dry-gas effluent volumetric flow to theoretical dry-gas effluent volumetric flow by the ratio of the actual dry-gas density to the theoretical dry-gas density by the ratio of the ratio of the theoretical wet fuel mass flow to the actual wet fuel mass flow resulting in the correction to the L Factor.

14. The method of claim 12, wherein the step of obtaining the ratio of actual dry-gas effluent mass flow to actual wet fuel mass flow includes the steps of:

obtaining an actual air/fuel ratio;

obtaining a weight fraction of water in the fossil fuel;

obtaining a weight fraction of ash in the fossil fuel; and

combining the actual air/fuel ratio, the weight fraction of water and the weight fraction of ash resulting in the ratio of actual dry-gas effluent mass flow to actual wet fuel mass flow.

15. The method of claim 12, wherein the step of obtaining the ratio of the theoretical wet fuel mass flow to the theoretical dry-gas effluent mass flow includes the steps of:

obtaining a molecular weight of the wet fuel;

obtaining a molecular weight of the wet-gas effluent based on theoretical combustion;

obtaining a ratio of the moles of wet fuel required to produce 100 moles of wet-gas effluent based on theoretical combustion; and

combining the molecular weight of the wet fuel, the molecular weight of the wet-gas effluent and the ratio of the moles of wet fuel required to produce 100 moles of wet-gas effluents resulting in the ratio of the theoretical wet fuel mass flow to the theoretical dry-gas effluent mass flow.