Liquefied natural gas vaporizer for downhole oil or gas applications

Patent metadata

Field	Value
Publication number	US-10544902-B2
Application number	US-201515522280-A
Country	US
Kind code	B2
Filing date	Nov 27, 2015
Priority date	Dec 2, 2014
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

A vaporizer apparatus for vaporizing liquefied natural gas (LNG) into vapor-phase natural gas for injection into an oil or gas well, comprises a blower assembly, a burner section, a heat exchanger section, and at least one flammable gas concentration sensor. The blower assembly comprises a primary blower configured to move air along an air flow path through the vaporizer apparatus and a flame arrestor configured to allow passage of the air into the vaporizer apparatus and impede passage of a flame out of the vaporizer apparatus. The burner section comprises an enclosure having an upstream end coupled to the blower assembly and a downstream end, and a burner inside the enclosure and in the air flow path for heating the air. The heat exchanger section comprises an enclosure having an upstream end coupled to the downstream end of the burner section enclosure and a downstream end, and at least one LNG heat exchange tube inside the enclosure and in the air flow path, and thermally communicable with the air heated by the burner. The at least one flammable gas concentration sensor is in the air flow path upstream of the burner and is configured to detect whether a concentration of a flammable gas in the air is above a flammable gas concentration set point.

First claim

What is claimed is:

1. A system for injecting vapor-phase natural gas into an oil or gas well, comprising:
(a) a pump configured to pressurize liquefied natural gas (LNG) to fracturing pressure; and
(b) a vaporizer apparatus for vaporizing LNG into the vapor-phase natural gas, the vaporizer apparatus fluidly coupled to the pump and comprising:
(i) a blower assembly comprising a primary blower configured to move air along a supply air flow path through the vaporizer apparatus;
(ii) a burner section comprising an enclosure having an upstream end coupled to the blower assembly and a downstream end, and at least one burner inside the enclosure and in the supply air flow path for heating the air;
(iii) a heat exchanger section comprising an enclosure having an upstream end coupled to the downstream end of the burner section enclosure and a downstream end, and at least one LNG heat exchange tube inside A the enclosure and in the supply air flow path, and thermally communicable with the air heated by the burner; and
(iv) at least one flammable gas concentration sensor in the air flow path upstream of the burner and configured to detect whether a concentration of a flammable gas in the air is above a flammable gas concentration set point.

2. A vaporizer apparatus as claimed in claim 1 wherein the blower assembly further comprises a flame arrestor configured to allow passage of the air into the vaporizer apparatus and impede passage of a flame out of the vaporizer apparatus.

3. A vaporizer apparatus as claimed in claim 1 wherein the at least one flammable gas concentration sensor comprises a gas concentration sensor mounted outside the vaporizer apparatus and in the supply air flow path upstream of the primary blower.

4. A vaporizer apparatus as claimed in claim 3 further comprising an exhaust duct having an upstream end coupled to the downstream end of the heat exchanger enclosure, and an outlet for discharging the air and combustion products from the vaporizer apparatus; and at least one ultraviolet or infrared flame detector in the exhaust duct.

5. A vaporizer apparatus as claimed in claim 1 further comprising at least one temperature sensor inside the vaporizer apparatus downstream of the burner, and configured to detect whether the temperature inside the vaporizer apparatus is above a temperature set point.

6. A vaporizer apparatus as claimed in claim 5 further comprising an exhaust duct having an upstream end coupled to the downstream end of the heat exchanger enclosure, an outlet for discharging the air and combustion products from the vaporizer apparatus, and wherein the at least one temperature sensor comprises an exhaust temperature sensor in the exhaust duct.

7. A vaporizer apparatus as claimed in claim 5 wherein the at least one temperature sensor comprises a heat exchanger temperature sensor inside the heat exchanger enclosure and configured to measure the temperature of the air blown by the primary blower and heated by the burner.

8. A vaporizer apparatus as claimed in claim 1 further comprising an exhaust duct having an upstream end coupled to the downstream end of the heat exchanger enclosure, an outlet for discharging the air and combustion products from the vaporizer apparatus, and wherein the at least one flammable gas concentration sensor comprises an exhaust gas concentration sensor in the exhaust duct.

9. A vaporizer apparatus as claimed in claim 1 wherein the blower assembly, burner section enclosure, and heat exchanger section enclosure are sealed or gasketed to produce at least a flame-tight air flow pathway through the inside of the vaporizer apparatus.

10. A vaporizer apparatus as claimed in claim 1 further comprising a cooling air assembly comprising a secondary cooling air source in air flow communication with the air moved by the primary blower and heated by the burner.

11. A vaporizer apparatus as claimed in claim 10 wherein the secondary cooling air source comprises a cooling air blower controllable independently from the primary blower.

12. A vaporizer apparatus as claimed in claim 1 further comprising a cooling air assembly comprising at least one cooling air duct having an inlet in air flow communication with the air moved by the primary blower but not heated by the burner, and an outlet in air flow communication with the air moved by the primary blower and heated by the burner, and a control valve in air flow communication with the at least one cooling air duct and operable to control the flow rate of air flowing therethrough.

13. A method for injecting vapor-phase natural gas into an oil or gas well, comprising:
(a) operating a primary blower to move air into the vaporizer apparatus;
(b) measuring a flammable gas concentration in the air;
(c) only when the measured flammable gas concentration is below a flammable gas concentration set point, operating a burner to provide the air with enough heat energy to vaporize LNG flowing through at least one heat exchange tube inside the vaporizer apparatus;
(d) operating a pump to pressurize the LNG to fracturing pressure; and
(e) injecting the vapor-phase natural gas into the oil or gas well.

14. A method as claimed in claim 13 further comprising: measuring a temperature of the air moved into the vaporizer apparatus and heated by the burner, and only when the measured temperature of the air is below a temperature set point, operating the burner to provide the air with enough heat energy to vaporize LNG flowing through at least one heat exchange tube inside the vaporizer apparatus.

15. A method as claimed in claim 14 further comprising: when the measured temperature of the heated air is at or above the temperature set point, adjusting the primary blower operation to increase the flow rate of the air through the vaporizer apparatus.

16. A method as claimed in claim 15 further comprising: when the measured temperature of the air is at or above the temperature set point, moving cooling air into the vaporizer apparatus to cool the air moved by the primary blower and heated by the burner.

17. A method as claimed in claim 14 further comprising: when the measured temperature of the air is at or above the temperature set point, decreasing a supply of burner fuel to the burner to reduce heating of the air by the burner.

18. A method as claimed in claim 14 further comprising at least one of: measuring a flammable gas concentration in exhaust air heated by the burner, and monitoring for a flame in the vaporizer apparatus downstream of the burner, and when the measured flammable gas concentration in the exhaust air is at or above the flammable gas concentration set point or when a flame is detected, stopping operation of the primary blower and burner.

19. A method as claimed in claim 18 wherein stopping operation of the primary blower and burner further comprises measuring the flammable gas concentration and air temperature inside the vaporizer and releasing an extinguishing gas into the vaporizer apparatus when at least one of the measured flammable gas concentration and air temperature is at or above the respective flammable gas concentration set point and temperature set point.

20. A method as claimed in claim 13 further comprising: when the measured flammable gas concentration is at or above the flammable gas concentration set point, stopping operation of the primary blower and burner.

21. A method as claimed in claim 20 wherein stopping operation of the primary blower and burner further comprises purging the vaporizer ap

Assignees

• Halliburton Energy Services Inc

Inventors

• Nevison Grant W

Classifications

• F17C2221/033

  Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG · CPC title

• B01B1/005

  Evaporation for physical or chemical purposes; Evaporation apparatus therefor, e.g. evaporation of liquids for gas phase reactions · CPC title

• F17C2227/0332

  by burning a combustible · CPC title

• F17C2223/0161

  cryogenic, e.g. LNG, GNL, PLNG · CPC title

• F17C2225/0123

  gaseous, e.g. CNG, GNC · CPC title