Emission monitoring of flare systems

Patent metadata

Field	Value
Publication number	US-12044641-B2
Application number	US-202117325876-A
Country	US
Kind code	B2
Filing date	May 20, 2021
Priority date	May 29, 2020
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

Systems and methods for monitoring emissions of a combusted gas are provided. The method includes determining a first net heating value of a flare gas. The method also includes determining a second net heating value of a combustion gas including the flare gas. The second net heating value can be determined based upon the first net heating value and a volumetric flow rate of the flare gas. Based upon the value of the second net heating value, an empirical model or a non-parametric machine learning model can be selected. A combustion efficiency of the combustion gas can be determined using the selected model, the second net heating value, and selected ones of the process conditions and the environmental conditions. Total emissions of the combustion mixture can be further determined from the combustion efficiency and a volumetric flow rate of the combustion gas.

First claim

The invention claimed is:

1. A method of monitoring emissions, comprising:
determining, in real-time, by one or more processors, a first net heating value (NHV) of a flare gas emitted from an industrial process;
determining, in real-time, by the one or more processors, a second net heating value (NHV CZ ) of a combustion gas within a combustion zone including at least the flare gas, wherein the second net heating value (NHV CZ ) is determined based upon the first net heating value (NHV) and a first volumetric flow rate of the flare gas;
comparing, in real-time, by the one or more processors, the second net heating value (NHV CZ ) to a predetermined criterion;
generating, in real-time, by an empirical model selected from a plurality of computational models a first estimate of combustion efficiency of the combustion gas when the second net heating value (NHV CZ ) is determined to satisfy the predetermined criterion;
generating, in real-time, by a non-parametric machine learning model selected from the plurality of computational models a second estimate of combustion efficiency of the combustion mixture when the second net heating value (NHV CZ ) does not satisfy the predetermined criterion;
determining, in real-time, by the one or more processors, a total emissions of the combustion gas based on the first or second combustion efficiency estimate; and
outputting, in real-time, by the one or more processors, the first or second combustion efficiency estimate corresponding to the selected model and the total emissions to a display communicatively coupled to the one or more processors to be viewed by a user.

2. The method of claim 1 , further comprising determining, in real-time, by the one or more processors, total emissions of the combustion gas based upon the output one of the first combustion efficiency estimate or the second combustion efficiency estimate.

3. The method of claim 1 , wherein determining, in real-time, the first net heating value (NHV) comprises receiving the first net heating value from a data storage device.

4. The method of claim 1 , wherein determining, in real-time, the first net heating value (NHV) comprises:
measuring, prior to combustion, a speed of sound in the flare gas, a pressure of the flare gas, and a temperature of the flare gas; and
determining, in real-time, by the one or more processors, a molecular weight of the flare gas based upon the measured speed of sound in the flare gas, the pressure of the flare gas, and the temperature of the flare gas.

5. The method of claim 4 , wherein the speed of sound in the flare gas is measured by an ultrasonic flow meter.

6. The method of claim 1 , further comprising:
measuring, in real-time, by a multi-spectral imaging system, absorption/emission spectra of the combustion gas; and
determining, in real-time, by the one or more processors, a third estimate of the combustion efficiency of the combustion gas based upon the measured spectra.

7. The method of claim 6 , further comprising adjusting, in real-time, the selected model such that the output combustion efficiency estimate is approximately equal to the third estimate of combustion efficiency.

8. The method of claim 1 , wherein the combustion gas further comprises a supplementary fuel gas and wherein the second net heating value (NHV CZ ) is further determined, in real-time, based upon a second volumetric flow rate of the supplementary fuel gas.

9. The method of claim 1 , wherein the combustion gas further comprises at least one assist gas and wherein the second net heating value (NHV CZ ) is further determined, in real-time, based upon a third volumetric flow rate of the assist gas.

10. The method of claim 1 , wherein the combustion gas further comprises a supplementary fuel gas and at least one assist gas and wherein the second net heating value (NHV CZ ) is further determined, in real-time, based upon a second volumetric flow rate of the supplementary fuel gas and a third volumetric flow rate of the at least one assist gas.

11. The method of claim 1 , wherein the conduit is a portion of a flare stack.

12. A system for monitoring emissions, comprising:
one or more processors configured to:
determine, in real-time, a first net heating value (NHV) of a flare gas emitted from an industrial process;
determine, in real-time, a second net heating value (NHV CZ ) of a combustion gas within a combustion zone including the flare gas, wherein the second net heating value (NHV CZ ) is determined based upon the first net heating value (NHV) and a first volumetric flow rate of the flare gas;
compare, in real-time, the second net heating value (NHV CZ ) to a predetermined criterion;
generate, in real-time, by an empirical model selected from a plurality of computational models, a first estimate of combustion efficiency of the combustion gas when the second net heating value (NHV CZ ) satisfies the predetermined criterion;
generate, in real-time, by a non-parametric machine learning model selected from a plurality of computational models, a second estimate of combustion efficiency of the combustion gas when the second net heating value (NHV CZ ) does not satisfy the predetermined criterion; and
output, in real-time, the selected one of the first combustion efficiency estimate or second combustion efficiency estimate corresponding to the selected model to a display communicatively coupled to the one or more processors to be viewed by a user,
provide, to a controller communicatively coupled to the one or more processors, a command signal configured to regulate the first volumetric flow rate of the flare gas based on the first or the second combustion efficiency estimate.

13. The system of claim 12 , wherein the one or more processors is further configured to determine, in real-time, total emissions of the combustion gas based upon the output one of the first combustion efficiency estimate or the second combustion efficiency estimate.

14. The system of claim 12 , further comprising a data storage device in communication with the one or more processors, wherein the one or more processors is further configured to determine, in real-time, the first net heating value (NHV) by receipt of the first net heating value from the data storage device.

15. The system of claim 12 , wherein the one or more processors is further configured to:
receive a speed of sound in the flare gas prior to combustion, a pressure of the flare gas prior to combustion, and a temperature of the flare gas prior to combustion; and
determine, in real-time, a molecular weight of the flare gas based upon the measured speed of sound in the flare gas, the pressure of the flare gas, and the temperature of the flare gas.

16. The system of claim 15 , further comprising:
a flow meter configured to measure the speed of sound in the flare gas and the flow rate of the flare gas prior to combustion;
a temperature sensor configured to measure the temperature of the flare gas;
a pressure sensor configured to measure the pressure of the flare gas.

17. The system of claim 15 , wherein the flow meter is an ultrasonic flow meter.

18. The system of claim 12 , further comprising a multi-spectral imaging system configured to measure spectra of the combustion gas, wherein the one or more processors is further configured to determine, in real-time, a third estimate of the combustion efficiency of the combustion gas based upon the measured spectra.

19. The system of claim 18 , wherein the one or more processors is further configured to adjust, in real-time, the selec

Assignees

• Baker Hughes Oilfield Operations Llc

Inventors

• Tao Chong
• Weling Aniruddha
• Sui Lei
• Kowal Anthony
• Muller Michael

Classifications

• F01N11/00

  Monitoring or diagnostic devices for exhaust-gas treatment apparatus · CPC title

• F23G5/50

  Control or safety arrangements · CPC title

• G01N25/20

  by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity (calorimeters per se G01K) · CPC title

• G01N2021/8411

  Application to online plant, process monitoring · CPC title

• G01N25/28

  the rise in temperature of the gases resulting from combustion being measured directly · CPC title