Landfill gas extraction systems and methods

Patent metadata

Field	Value
Publication number	US-11235361-B2
Application number	US-202017086987-A
Country	US
Kind code	B2
Filing date	Nov 2, 2020
Priority date	Oct 1, 2018
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

Described herein are embodiments of a control system that automatically (1) determines whether a gas extraction system is in a state in which landfill gas is being released into the atmosphere, and (2) automatically controls landfill gas flow to mitigate, prevent and/or stop the release of landfill gas. The control system may control a valve to control flow of landfill gas through well piping of the gas extraction system. The pressure of landfill gas in the well piping at a location upstream of the valve may indicate whether there is a risk of landfill gas being released into the atmosphere. The control system may adjust a position of the valve in response to determining that the pressure at the location upstream of the valve indicates that there is a risk of landfill gas being released into the atmosphere.

First claim

What is claimed is:

1. A control system for controlling extraction of landfill gas from a landfill via a gas extraction system, the gas extraction system comprising well piping for coupling a well to a gas output, the control system comprising:
a controller configured to:
obtain a measure of landfill gas pressure upstream of a valve disposed in the well piping, the valve being for controlling the flow of landfill gas through the well piping to the gas output;
obtain a measure of landfill gas pressure downstream of the valve;
determine whether the measure of the landfill gas pressure upstream of the valve is greater than a first threshold pressure;
determine whether the measure of landfill gas pressure downstream of the valve is less than a second threshold pressure; and
in response to determining that the measure of landfill gas pressure upstream of the valve is greater than the first threshold pressure and the measure of the landfill gas pressure downstream of the valve is less than the second threshold pressure, control the valve to reduce the landfill gas pressure upstream of the valve.

2. The control system of claim 1 , wherein the controller is configured to control the valve to reduce the landfill gas pressure upstream of the valve by increasing a degree to which the valve is open.

3. The control system of claim 2 , wherein the controller is configured to control the valve to increase the degree to which the valve is open by an amount that is proportional to a ratio of the measure of landfill gas pressure upstream of the valve to the first threshold pressure.

4. The control system of claim 1 , further comprising at least one sensor configured to obtain the measure of the landfill gas pressure upstream of the valve and the measure of the landfill gas pressure downstream of the valve.

5. The control system of claim 4 , wherein the at least one sensor comprises:
a first pressure sensor configured to obtain the measure of landfill gas pressure upstream of the valve; and
a second pressure sensor configured to obtain the measure of landfill gas pressure downstream of the valve.

6. The control system of claim 5 , wherein the first pressure sensor is configured to measure landfill gas pressure in the well piping at a location upstream of the valve, and the second pressure sensor is configured to measure landfill gas pressure in the well piping at a location downstream of the valve.

7. The control system of claim 1 , wherein the second threshold pressure is approximately −5 mbar.

8. The control system of claim 1 , wherein the first threshold pressure is approximately 0.0 mbar.

9. The control system of claim 1 , wherein the first threshold pressure is approximately −1 mbar.

10. The control system of claim 1 , wherein the controller is configured to control the valve to reduce the landfill gas pressure upstream of the valve by:
increasing a degree to which the valve is open by a first amount; and
after increasing the degree to which the valve is open by the first amount:
obtaining a second measure of landfill gas pressure upstream of the valve; and
in response to determining that the second measure of landfill gas pressure upstream of the valve is greater than the first threshold pressure, increasing the degree to which the valve is open by the first amount.

11. The control system of claim 1 , wherein the controller is configured to:
in response to determining that the measure of landfill gas pressure upstream of the valve is greater than the first threshold pressure:
store a record of the measure of landfill gas pressure upstream of the valve;
store a record of controlling the valve to reduce landfill gas pressure upstream of the valve; and
store a record of a second measure of landfill gas pressure upstream of the valve after controlling the valve to reduce the landfill gas pressure upstream of the valve.

12. The control system of claim 1 , wherein the controller is configured to:
in response to determining that the measure of landfill gas pressure upstream of the valve is less than or equal to the first threshold pressure, control the valve by maintaining a position of the valve.

13. A method of controlling extraction of landfill gas from a landfill via a gas extraction system, the method comprising:
obtaining a measure of landfill gas pressure upstream of a valve disposed in well piping of the gas extraction system, the valve being for controlling flow of landfill gas through the well piping from the landfill to a gas output;
obtaining a measure of landfill gas pressure downstream of the valve;
determining whether the measure of landfill gas pressure upstream of the valve is greater than a first threshold pressure;
determining whether the measure of landfill gas pressure downstream of the valve is less than a second threshold pressure; and
in response to determining that the measure of landfill gas pressure upstream of the valve is greater than the first threshold pressure and the measure of landfill gas pressure downstream of the valve is less than the second threshold pressure, controlling the valve to reduce the landfill gas pressure upstream of the valve.

14. The method of claim 13 , wherein controlling the valve to reduce the landfill gas pressure upstream comprises increasing a degree to which the valve is open.

15. The method of claim 13 , wherein:
obtaining the measure of landfill gas pressure upstream of the valve comprises obtaining the measure of landfill gas pressure upstream of the valve with a first pressure sensor; and
obtaining the measure of landfill gas pressure downstream of the valve comprises obtaining the measure of landfill gas pressure downstream of the valve with a second pressure sensor.

16. The method of claim 15 , wherein:
the first pressure sensor is configured to measure landfill gas pressure in the well piping at a location upstream of the valve, and the second pressure sensor is configured to measure landfill gas pressure in the well piping at a location downstream of the valve.

17. The method of claim 13 , wherein the second threshold pressure is approximately −5 mbar.

18. The method of claim 13 , wherein the first threshold pressure is approximately 0.0 mbar.

19. A method of controlling extraction of landfill gas from a landfill via a gas extraction system, the method comprising:
obtaining a measure of landfill gas pressure upstream of a valve disposed in well piping of the gas extraction system, the valve being for controlling flow of landfill gas through the well piping from the landfill to a gas output;
obtaining a measure of landfill gas pressure downstream of the valve;
determining whether the measure of landfill gas pressure upstream of the valve is greater than a first threshold pressure;
determining whether the measure of landfill gas pressure downstream of the valve is less than a second threshold pressure; and
in response to determining that the measure of landfill gas pressure upstream of the valve is greater than the first threshold pressure and the measure of landfill gas pressure downstream of the valve is not less than the second threshold pressure, controlling the valve to maintain the landfill gas pressure upstream of the valve by maintaining a position of the valve.

20. The method of claim 19 , wherein:
obtaining the measure of landfill gas pressure upstream of the valve comprises obtaining the measure of landfill gas pressure upstream of the valve with a first pressure sensor configured to measure landfill gas pressure in

Assignees

• Loci Controls Inc

Inventors

• Quigley Peter
• Martin Ian
• Neff Nicole
• Rowbottom Jack

Classifications

• B09C1/005

  Extraction of vapours or gases using vacuum or venting · CPC title

• B09B1/00 Primary

  Dumping solid waste · CPC title

• B09B1/006 Primary

  Shafts or wells in waste dumps · CPC title

• Y02W30/30

  Landfill technologies aiming to mitigate methane emissions · CPC title

• E21B34/02

  in well heads · CPC title