Input/loss method for determining boiler efficiency of a fossil-fired system

• US 6,584,429 B1
• Filed: 08/02/2000
• Issued: 06/24/2003
• Est. Priority Date: 08/06/1999
• Status: Expired due to Term

• Current Assignee: Exergetic Systems LLC
• Original Assignee: Exergetic Systems LLC
• Inventors: Lang, Fred D.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Barbee, Manuel L.
• Application Number:
  US09/630,853
• Time in Patent Office: 1,056 Days
• Field of Search: 702/31, 702/32, 702/40, 702/45, 702/50, 702/55, 702/99, 702/100, 702/130, 702/132, 702/134, 702/136, 702/182, 702/183, 702/188, 374/36, 374/43, 374/45, 700/274, 700/275, 700/282
• US Class Current: 702/182
• CPC Class Codes: F23N 1/002 using electronic means F23N1/04 - F23N1/10 take precedence
• CPC Class Codes: F23N 2221/10 Analysing fuel properties, e.g. density, calorific

Abstract

The operation of a fossil-fueled thermal system is quantified by obtaining an unusually accurate boiler efficiency. Such a boiler efficiency is dependent on the calorimetric temperature at which the fuel'"'"'s heating value is determined. This dependency affects the major thermodynamic terms comprising boiler efficiency.

Claims

1. A method for determining a higher heating value boiler efficiency for a thermal system which applies consistently a fuel'"'"'s calorimetric temperature, comprising the steps of:

(a) determining a fuel'"'"'s higher heating value and the associated calorimetric temperature;

(b) equating a thermodynamic reference temperature used to evaluate a boiler'"'"'s energy flows, to the calorimetric temperature as established when determining the fuel'"'"'s higher heating value;

(c) calculating an Enthalpy of Products, an Enthalpy of Reactants and a Firing Correction as a function of the fuel'"'"'s higher heating value, common system parameters, and the thermodynamic reference temperature;

(d) calculating the combustion efficiency as a function of the higher heating value, the Enthalpy of Products, the Enthalpy of Reactants, and the Firing Correction;

(e) calculating a boiler efficiency from the combustion efficiency and a boiler absorption efficiency;

(f) calculating a fuel flow to the thermal system from the boiler efficiency, an energy delivered from the combustion process, the fuel'"'"'s higher heating value and the Firing Correction; and

(g) calculating an effluent flow output from the thermal system from the fuel flow and system stoichiometrics.

2. A method for determining higher heating value boiler efficiency for a thermal system which applies consistently any thermodynamic reference temperature, comprising the steps of:

(a) determining a fuel'"'"'s higher heating value;

(b) using any thermodynamic reference temperature to evaluate a boiler'"'"'s energy flows, wherein a reasonable change in the thermodynamic reference temperature does not substantially affect a computed boiler efficiency or a computed fuel flow;

(c) calculating an Enthalpy of Products, an Enthalpy of Reactants and a Firing Correction as a function of the fuel'"'"'s higher heating value, common system parameters, and the thermodynamic reference temperature;

(d) calculating the combustion efficiency as a function of the higher heating value, the Enthalpy of Products, the Enthalpy of Reactants, and the Firing Correction;

(e) calculating a boiler efficiency from the combustion efficiency and a boiler absorption efficiency;

(f) calculating a fuel flow to the thermal system from the boiler efficiency, an energy delivered from the combustion process, the fuel'"'"'s higher heating value and the Firing Correction; and

(g) calculating an effluent flow output from the thermal system using the fuel flow and system stoichiometrics.

3. A method for determining higher heating value boiler efficiency, comprising the concept of using a fuel'"'"'s calorimetric temperature for the thermodynamic reference energy level of an Enthalpy of Products term, for the thermodynamic reference energy level of an Enthalpy of Reactants term, and also for the thermodynamic reference energy level of a Firing Correction term evaluated independent of a fuel flow and an effluent flow, said terms comprising the major terms of a computed boiler efficiency.

4. A method for determining a lower heating value boiler efficiency for a thermal system which applies consistently a fuel'"'"'s calorimetric temperature, comprising the steps of:

(a) determining a fuel'"'"'s lower heating value and the associated calorimetric temperature;

(b) equating a thermodynamic reference temperature used to evaluate a boiler'"'"'s energy flows, to the calorimetric temperature as established when determining the fuel'"'"'s lower heating value;

(c) calculating an Enthalpy of Products, an Enthalpy of Reactants and a Firing Correction as a function of the fuel'"'"'s lower heating value, common system parameters, and the thermodynamic reference temperature;

(d) calculating the combustion efficiency as a function of the lower heating value, the Enthalpy of Products, the Enthalpy of Reactants, and the Firing Correction;

(e) calculating a boiler efficiency from the combustion efficiency and a boiler absorption efficiency;

(f) calculating a fuel flow to the thermal system from the boiler efficiency, an energy delivered from the combustion process, the fuel'"'"'s lower heating value and the Firing Correction; and

(g) calculating an effluent flow output from the thermal system from the fuel flow and system stoichiometrics.

5. A method for determining lower heating value boiler efficiency for a thermal system which applies consistently any thermodynamic reference temperature, comprising the steps of:

(a) determining a fuel'"'"'s lower heating value;

(b) using any thermodynamic reference temperature to evaluate a boiler'"'"'s energy flows, wherein a reasonable change in the thermodynamic reference temperature does not substantially affect a computed boiler efficiency or a computed fuel flow;

(c) calculating an Enthalpy of Products, an Enthalpy of Reactants and a Firing Correction as a function of the fuel'"'"'s lower heating value, common system parameters, and the thermodynamic reference temperature;

(d) calculating the combustion efficiency as a function of the lower heating value, the Enthalpy of Products, the Enthalpy of Reactants, and the Firing Correction;

(e) calculating a boiler efficiency from the combustion efficiency and a boiler absorption efficiency;

(f) calculating a fuel flow to the thermal system from the boiler efficiency, an energy delivered from the combustion process, the fuel'"'"'s lower heating value and the Firing Correction; and

(g) calculating an effluent flow output from the thermal system using the fuel flow and system stoichiometrics.

6. A method for determining lower heating value boiler efficiency, comprising the concept of using a fuel'"'"'s calorimetric temperature for the thermodynamic reference energy level of an Enthalpy of Products term, for the thermodynamic reference energy level of an Enthalpy of Reactants term, and also for the thermodynamic reference energy level of a Firing Correction term evaluated independent of a fuel flow and an effluent flow, said terms comprising the major terms of a computed boiler efficiency.

7. A method to evaluate either higher or lower heating value efficiencies such that their computed fuel flows are not sensitive to reasonable changes in a thermodynamic reference temperature used to determine the energy level of an Enthalpy of Products term, used to determine the energy level of an Enthalpy of Reactants term, and also used to determine the energy level of a Firing Correction term evaluated independent of a fuel flow and an effluent flow, said terms comprising the major terms of a computed boiler efficiency.

8. A method to evaluate either higher or lower heating value efficiencies such that their computed fuel flows are the same, comprising the steps of:

(a) determining a fuel'"'"'s higher heating value;

(b) calculating an Enthalpy of Products and an Enthalpy of Reactants based on the fuel'"'"'s higher heating value, common system parameters and a thermodynamic reference temperature;

(c) calculating a Firing Correction based on common system parameters and a thermodynamic reference temperature;

(d) calculating the difference between the Enthalpy of Products and the Enthalpy of Reactants, both based on the fuels'"'"' higher heating value;

(e) calculating the higher heating value combustion efficiency as a function of the fuel'"'"'s higher heating value, the difference in the Enthalpy of Products and the Enthalpy of Reactants as based on the fuel'"'"'s higher heating value, and the Firing Correction;

(f) calculating a higher heating value boiler efficiency from the higher heating value combustion efficiency and a boiler absorption efficiency;

(g) determining a fuel'"'"'s lower heating value;

(h) calculating an Enthalpy of Products and an Enthalpy of Reactants based on the fuel'"'"'s lower heating value, common system parameters and a thermodynamic reference temperature;

(i) calculating a Firing Correction based on common system parameters and a thermodynamic reference temperature;

(j) calculating the difference between the Enthalpy of Products and the Enthalpy of Reactants, both based on the fuels'"'"' lower heating value;

(k) calculating the lower heating value combustion efficiency as a function of the fuel'"'"'s lower heating value, the difference in the Enthalpy of Products and the Enthalpy of Reactants as based on the fuel'"'"'s lower heating value, and the Firing Correction;

(l) calculating a lower heating value boiler efficiency from the lower heating value combustion efficiency and a boiler absorption efficiency;

(m) calculating a fuel flow to the thermal system from either the higher heating value boiler efficiency of step (f), an energy delivered from the combustion process, the fuel'"'"'s higher heating value and the Firing Correction, or from the lower heating value boiler efficiency of step (l), an energy delivered from the combustion process, the fuel'"'"'s lower heating value and the Firing Correction, such that these fuel flows are the same.

9. A method for determining a higher heating value boiler efficiency for a thermal system which applies consistently a fuel'"'"'s calorimetric temperature, comprising the steps of:

(a) determining a fuel'"'"'s higher heating value and the associated calorimetric temperature;

(b) equating a thermodynamic reference temperature used to determine the energy levels of the major terms of computed boiler efficiency, to the calorimetric temperature as established when determining the fuel'"'"'s higher heating value;

(c) calculating an Enthalpy of Products, an Enthalpy of Reactants, and a Firing Correction as a function of the fuel'"'"'s higher heating value, common system parameters, and the thermodynamic reference temperature;

(d) determining a set of losses effecting computed boiler efficiency;

(d) calculating a boiler efficiency as a function of the higher heating value, the Enthalpy of Products, the Enthalpy of Reactants, the Firing Correction, and the set of losses; and

(e) reporting the boiler efficiency.

10. The method of claim 9, further comprising an additional step, after the step of reporting, of:

(f) calculating a fuel flow to the thermal system based on the boiler efficiency, an energy flow delivered from the combustion process, the fuel'"'"'s higher heating value, and the Firing Correction.

11. The method of claim 10, further comprising an additional step, after the step of calculating the fuel flow, of:

(g) calculating an effluent flow output from the thermal system based on the fuel flow and system stoichiometrics.

12. A method for determining a lower heating value boiler efficiency for a thermal system which applies consistently a fuel'"'"'s calorimetric temperature, comprising the steps of:

(a) determining a fuel'"'"'s lower heating value and the associated calorimetric temperature;

(b) equating a thermodynamic reference temperature used to determine the energy levels of the major terms of computed boiler efficiency, to the calorimetric temperature as established when determining the fuel'"'"'s lower heating value;

(c) calculating an Enthalpy of Products, an Enthalpy of Reactants, and a Firing Correction as a function of the fuel'"'"'s lower heating value, common system parameters, and the thermodynamic reference temperature;

(d) determining a set of losses effecting computed boiler efficiency;

(d) calculating a boiler efficiency as a function of the lower heating value, the Enthalpy of Products, the Enthalpy of Reactants, the Firing Correction, and the set of losses; and

(e) reporting the boiler efficiency.

13. The method of claim 12, further comprising an additional step, after the step of reporting, of:

(f) calculating a fuel flow to the thermal system based on the boiler efficiency, an energy flow delivered from the combustion process, the fuel'"'"'s lower heating value, and the Firing Correction.

14. The method of claim 13, further comprising an additional step, after the step of calculating the fuel flow, of:

(g) calculating an effluent flow output from the thermal system based on the fuel flow and system stoichiometrics.