Method of cleaning pressurized containers containing anhydrous ammonia

• US 6,758,913 B1
• Filed: 10/12/2000
• Issued: 07/06/2004
• Est. Priority Date: 10/12/2000
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Tunney, Joseph P., Buchan, Paul
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): Winter, Gentle E.
• Application Number:
  US09/689,035
• Time in Patent Office: 1,363 Days
• Field of Search: 134/10, 134/21, 134/104, 141/4, 220/749, 431/18, 431/22, 431/202
• US Class Current: 134/21
• CPC Class Codes: B08B 7/00 Cleaning by methods not provided for in a single other subclass or a single group in this subclass
• CPC Class Codes: B08B 9/08 Cleaning containers, e.g. tanks

Abstract

The present invention relates to a method of cleaning a container having an amount of anhydrous ammonia contained therein. The container is first inspected thoroughly for leaks. Heated nitrogen gas is then fed into the container. The heated nitrogen gas may be transported from a nitrogen storage tank to the container via at least one pipe. Liquid nitrogen may be fed into a vaporizer for vaporizing the nitrogen. The liquid nitrogen gas may then be heated via a heater, such as a steamer, to expand the nitrogen gas and ensure that no liquid nitrogen enters the container. The heated nitrogen gas may vaporize any liquid anhydrous ammonia contained therein. Further, the heated nitrogen gas may transport the anhydrous ammonia to a flare for incineration. The heated nitrogen gas may be added any number of times to reduce the concentration of the anhydrous ammonia therein to a desired level. The container may then be steam cleaned and opened to enter and thoroughly clean the inside of the container.

Claims

1. A method of cleaning a pressurized container, the method comprising the steps of:

providing a pressurized container containing an amount of anhydrous ammonia wherein the container has inlet and outlet valves;

injecting a quantity of heated nitrogen gas into the container to form a nitrogen/anhydrous ammonia mixture; and

venting the nitrogen/anhydrous ammonia mixture to a flare,

wherein said heated nitrogen gas is a sufficient temperature and pressure such that injection of the heated nitrogen gas and venting of said gas to a flare occurs without mechanical means; and

repeating the injection of the container with heated nitrogen gas and venting the mixture to the flare until the concentration of anhydrous ammonia is less than or equal to about 10,000 ppm.

2. The method of claim 1 further comprising the steps of:

providing a natural gas inlet for feeding natural gas to a burn ring within the flare;

feeding the nitrogen/anhydrous ammonia mixture to the burn ring.

3. The method of claim 1 further comprising the steps of:

providing a blower for flowing air into the flare; and

blowing air into the flare via the blower to aid in the burning of the anhydrous ammonia.

4. The method of claim 1 further comprising the steps of:

visually looking for leaks in the container;

providing a housing having a cover on the container having a plurality of valves therein and a plurality of sideports for access to the interior of the housing;

sampling the interior of the housing via the sideport for a quantity of anhydrous ammonia via a chemical detecting instrument for leaks; and

removing the cover of the housing to inspect the interior of the housing for leaks.

5. The method of claim 1 further comprising the steps of:

weighing the container; and

comparing the weight of the container to a tare weight of the container to determine a weight of the anhydrous ammonia therein.

6. The method of claim 1 further comprising the steps of:

providing a nitrogen tank having nitrogen contained therein;

attaching a nitrogen line between the nitrogen tank and a first valve of the container;

heating a portion of the nitrogen line to heat nitrogen contained within the nitrogen line; and

attaching a flare line between the container and the flare.

7. The method of claim 1 further comprising the steps of:

sampling a quantity of anhydrous ammonia in vapor form to determine a concentration of vapor within the container, and

verifying the identity of the anhydrous ammonia within the container.

8. The method of claim 1 wherein the nitrogen gas is heated to between 100°

F. and 300°

F.

9. The method of claim 1 further comprising the steps of:

inspecting the container for leaks via a leak detection apparatus; and

stopping the cleaning of the container if a leak of the nitrogen/anhydrous ammonia mixture is found wherein said anhydrous ammonia is present in the nitrogen/anhydrous ammonia mixture emanating from the leak at a concentration of at least 50 ppm.

10. The method of claim 1 further comprising the steps of:

injecting the heated nitrogen into the container via a liquid valve on the container; and

venting the gas within the container to the flare via one of the valves.

15. The method of claim 1 further comprising the steps of:

a weighing the container; and

comparing the weight of the container to a tare weight of the container to determine a weight of the anhydrous ammonia therein.

11. A method of cleaning a pressurized container, the method comprising the steps of:

providing a pressurized container comprising an amount of anhydrous ammonia wherein the container has a plurality of valves;

injecting a quantity of heated nitrogen gas into the container to form a nitrogen/anhydrous ammonia mixture;

venting the nitrogen/anhydrous ammonia mixture to a flare,

wherein said heated nitrogen gas is a sufficient temperature and pressure such that injection of the heated nitrogen gas and venting of said nitrogen/anhydrous ammonia mixture occurs without mechanical means; and

repeating injecting the container with the heated nitrogen gas and venting the mixture to the flare until the concentration of the anhydrous ammonia is at most about 50 ppm.

12. The method of claim 11 further comprising the steps of:

inspecting the container for leaks.

13. The method of claim 11 further comprising the steps of:

inspecting the container for leaks via a leak detection apparatus; and

stopping the cleaning of the container if a leak of the nitrogen/anhydrous ammonia mixture is found wherein said anhydrous ammonia is present in the nitrogen/anhydrous ammonia mixture emanating from the leak at a concentration of at least about 50 ppm.

14. The method of claim 11 further comprising the steps of:

visually looking for leaks in the container;

providing a housing having a cover and an interior space wherein a plurality of valves are contained within the interior space;

providing at least one sideport in the housing for accessing the interior space of the housing;

sampling the interior of the housing via the sideport for a leak in the plurality of valves via a chemical detection device; and

removing the cover to inspect the interior space of the housing for leaks.

16. The method of claim 11 further comprising the steps of:

providing a nitrogen tank having nitrogen therein;

attaching a nitrogen line between a nitrogen tank and a first valve of the container;

heating a portion of the nitrogen line to heat nitrogen contained within the nitrogen line; and

attaching a flare line between the container and a flare.

17. The method of claim 11 further comprising the steps of:

sampling a quantity of anhydrous ammonia contained in the headspace of the container to determine a concentration of the anhydrous ammonia within the headspace.

18. The method of claim 11 wherein the nitrogen gas is heated to between 100°

F. and 300°

F.

19. The method of claim 11 further comprising the steps of:

injecting the heated nitrogen into the container via a liquid valve on the container; and

venting the nitrogen/anhydrous ammonia mixture within the container to the flare via a vapor valve on the container.

20. The method of claim 11 further comprising the steps of:

injecting the container with steam after the concentration of the anhydrous ammonia therein is about 50 ppm;

removing the pressure plate on the container; and

entering the container and cleaning debris from the container.