CA3090120A1

CA3090120A1 - A process and system for recovering contaminants from production water

Info

Publication number: CA3090120A1
Application number: CA3090120A
Authority: CA
Inventors: James Madsen
Original assignee: Optivus Engineering Ltd
Current assignee: Optivus Engineering Ltd
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2022-02-14

Abstract

A process and associated system for removing contaminants from production water is described. The method involves passing production water through an ad sorption med ia in order to capture hydrocarbon contaminants. The method further involves subjecting the adsorption media to a heat treatment until the contaminants undergo a phase change to gaseous form. The method finally involves condensing the contaminants in the gaseous form to a liquid fonn and capturing the contaminants in the liquid form.

Description

TITLE
[0001] A process and system for recovering contaminants from production water FIELD

[0002] There is described a process and system for recovering contaminants from production water.
BACKGROUND

[0003] A by-product of oil and gas production is water that was either trapped in the same deep formations as the oil and gas, water that was injected to stimulate a formation (e.g., hydraulic fracturing), or water that was injected to enhance oil recovery.
This water by-product is commonly known as "production water". Production water is generally disposed of by injection into disposal wells.

[0004] Due to environmental concerns over the use of fresh water, there has been pressure placed upon the oil and gas industry to use production water. Production water is highly saline and contaminated with noxious compounds including B1EX (benzene, toluene, ethyl benzene, and xylene), alkanes, and other hydrocarbons. Untreated production water stored in atmospheric storage ponds creates safety and environmental risks through the release of the noxious emissions created by the contaminants.

[0005] Efforts are now being made to remove contaminants from production water, so the production water can be safely stored. Activated carbon technology is one medium currently being used to remove contaminants from production water. Activated carbon saturated by contaminants is currently being disposed of at landfill sites.
SUMMARY

[0006] According to one aspect there is provided a process for removing contaminants from production water, which involves passing production water through an adsorption media in order to capture hydrocarbon contaminants. The process then involves subjecting the adsorption media to a heat treatment until the contaminants undergo a phase change to gaseous fon'', condensing the contaminants in the gaseous form to a liquid form, and capturing the contaminants in the liquid form.
Date Recue/Date Received 2020-08-14

[0007] While the process, as described above, works with any adsorption media capable of adsorbing hydrocarbon contaminants, in various forms, beneficial results have been obtained through the use of a combination of activated and bio carbon adsorption media.
It is prefened that the adsorption media used be in a granulated form, as the granulated form is easier to handle and manipulate.

[0008] While the process, as described above, will work whether the de-contaminated water is put to use directly after de-contamination or stored for later use, it is anticipated that after removal of the contaminants, the production water will be stored in uncovered water storage ponds in accordance with standard oil and gas industry practices.

[0009] While the process, as described above, will work to some degree as long as the contaminated production water is flowing through the adsorption media, it is preferred that the flow rate through the adsorption media be closely controlled. Controlling the flow rate will allow for the most optimal removal of contaminants from the production water, as the effectiveness of the adsorption media depends upon time exposure.

[0010] While the process, as described above, will work with some contaminants at lower temperature ranges, it is preferred that the adsorption media is subjected to heat treatment at temperatures of between 650 and 850 degrees Celsius, as some contaminants (such as B l'EX) will only be combusted or undergo a phase change to gaseous form at temperatures of between 650 and 850 degrees Celsius.

[0011] While the process described above will work without any agitation, it is preferred that the adsorption media is agitated during the heat treatment. Agitation will assist with exposure of the contaminants to both heat and combustion air.

[0012] According to another aspect there is described a system that was developed for the purpose of implementing the method. There is provided a system for removing contaminants from production water, which includes an adsorption media module, an adsorption media rejuvenation module, and a hydrocarbon contaminants recovery module.
Date Recue/Date Received 2020-08-14

[0013] The adsorption media module includes one or more elongated vessels that contain an adsorption media capable of adsorbing hydrocarbons. The one or more elongated vessels have a first end and a second end. There is a water inlet at the first end and a water outlet at the .. second end. There is also a media inlet at the first end. The one or more elongated vessels are in a generally horizontal orientation. The adsorption media module also includes a flow control assembly for controlling a flow rate of production water through the one or more elongated vessels from the inlet to the outlet.

[0014] The adsorption media rejuvenation module includes a kiln for subjecting the adsorption media to a heat treatment until the contaminants undergo a phase change to gaseous form.

[0015] The hydrocarbon contaminants recovery module includes at least one cooler-condenser for condensing the contaminants in the gaseous form to a liquid fonn, and a storage container for capturing the contaminants in the liquid form.

[0016] While the one or more elongated vessels are in a substantially horizontal orientation to assist with flow control, it is preferred that the one or more elongated vessels oriented at an oblique angle relative to a horizontal plane, with the first end positioned above the second end.
The slightly elevated horizontal position allows the water to slowly flow through the adsorption media by operation of gravity. The slightly elevated position also encourages the flow of adsorption media from the first end to the second end via the operation of gravity. This results in gravity assisting in loading the adsorption media into the elongated vessels and gravity .. assisting in the unloading of adsorption media once the adsorption media is fully saturated. The generally horizontal position also provides a more convenient point of access for operators to load and unload the media. It is preferred that the one or more elongated vessels are oriented an oblique angle of between 10 and 30 degrees. This angle of orientation provides an optimal amount of gravity assistance in both the movement of production water through the elongated vessels and the loading and unloading of adsorption media.

[0017] While the adsorption media rejuvenation module will work with any commercially available standard kiln that can subject the adsorption media to heat, it is prefen-ed that the kiln Date Recue/Date Received 2020-08-14 used is a rotary kiln. A rotary kiln will be able to subject the adsorption media to a heat treatment with agitation until the contaminants undergo a phase change to gaseous form. The added agitation assists with the efficient removal of contaminants from the adsorption media.

[0018] While different ways exist to move the contaminants in gaseous form from the kiln to the at least one cooler-condenser, it is preferred that at least one compressor is used to thaw contaminants in gaseous form from the kiln into the at least one cooler-condenser. Use of a compressor is advantageous as it will assist in the cooling and condensing of the hot gaseous contaminants.

[0019] While the one or more elongated vessels in the adsorption media module may be of a variety of materials, it is prefen-ed that the one or more elongated vessels are of a non-corrosive material. Some contaminants, such as hydrogen sulphide, are highly corrosive. It is further preferred that the non-corrosive material is a high-density polyethylene polymer plastic (HDPE). Use of a non-corrosive material will increase the life span of the elongated vessels.

[0020] While the adsorption media rejuvenation module can remove contaminants withjust the application of heat in the kiln, it is preferred that an air source provide limited amounts of air to the kiln. It will be understood that excessive amounts of air can cause an explosion, but some air is desirable to facilitate oxidization and combustion required for the effective removal of contaminants from the adsorption media.
BRIEF DESCRIPTION OF THE DRAWINGS

[0021] These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:

[0022] FIG.
1 is a flow diagram of the process and system for recovering contaminants from production water.

[0023] FIG. 2 is a perspective view of an adsorption media module of the system for recovering contaminants.

[0024] FIG.
3 is a side elevation view of a flow control assembly for the adsorption media module of FIG. 2.
Date Recue/Date Received 2020-08-14

[0025] FIG.
4 is a side elevation view of a rotary kiln used as part of an adsorption media rejuvenation module of the system for recovering contaminants.
DETAILED DESCRIPTION

[0026] A system for removing contaminants from production water will now be described with reference to FIG. 1 through FIG. 4.
Structure and Relationship of Parts:

[0027] Referring to FIG. 1, a system100 for removing contaminants fromproduction water includes an adsorption media module 200, an adsorption media rejuvenation module 300, and a hydrocarbon contaminants recovery module 400.

[0028]
Referring to FIG. 2, adsorption media module 200 includes two elongated vessels 202 containing an adsorption media (not shown) capable of adsorbing hydrocarbons. The Adsorption media is a combination of activated and bio carbon adsorption media in granulated form. The two elongated vessels 202 have a first end 206, a second end 208, a water inlet 210 at a first end 206 and a water outlet 212 at a second end 208. There is also a media inlet 214 at first end 206. Media inlet 214 has a removable flange 213 and a valve connection 215 for the loading of adsorption media. The two elongated vessels 202 are in a generally horizontal orientation, and at an oblique angle of between 10 and 30 degrees relative to a horizontal plane, with first end 206 positioned above second end 208. The two elongated vessels 202 are placed on a skid 217 for transport to well sites. The two elongated vessels 202 are of a non-corrosive high-density polyethylene polymer plastic (HDPE). Referring to FIG. 3, there is a flow contni assembly 218 controlling a flow rate of production water into water inlet 210 of two elongated vessels 202. Flow control assembly 218 includes a primary filter 219, a secondary filter 221, and valves 220.

[0029]
Referring to FIG. 1, a de-contaminated water storage facility 500 is available for the storage of de-contaminated production water.

[0030]
Referring to FIG. 4, adsorption media rejuvenation module 300 includes a rotaiy kiln 302 for subjecting adsorption media to a heat treatment with agitation until the Date Recue/Date Received 2020-08-14 contaminants undergo a phase change to gaseous form. The source of the heat generated by the rotary kiln 302 is high voltage, three phase electricity. Referring to FIG. 1, adsorption media rejuvenation module 300 also includes an air source 304 for supplying air to rotary kiln 302.
Rotary kiln 302 has a gas outlet 306 for the evacuation of the contaminants in gaseous form.

[0031] Referring to FIG. 1, hydrocarbon contaminants recovery module 400 includes a compressor 402 for drawing contaminants in gaseous form from the rotary kiln 302 through gas outlet 306, a cooler-condenser 404 for condensing the contaminants in the gaseous form to a liquid fon'', and a storage container 406 for capturing the contaminants in the liquid form.

[0032] Referring to FIG. 1, a disposal well 600 is available for the disposal of the contaminants in liquid form.
Operation:

[0033] Referring to FIG. 1, the process involves a first step of passing production water through adsorption media, which is a combination of activated and bio carbon, at a controlled flow rate in order to capture hydrocarbon contaminants. Referring to FIG. 2, this is achieved by operating the adsorption media module 200, which include two elongated vessels 202.
Adsorption media is pumped in to elongated vessels 202 as a slurry through valve connection 215 at media inlet 214, which is located at first end 206. Alternatively, flange 213 may be removed and dry adsorption media may be added pneumatically. The elevated position of fist end 206 above the second end 208, allows the adsorption media to slide down to the second end by the operation of gravity. Adsorption media is loaded into the two elongated vessels 202 until the two elongated vessels 202 are completely filled. Once adsorption media is loaded into the two elongated vessels 202, adsorption media module 200 is ready for the intake of production water. Referring to FIG. 3, before production water is pumped into adsorption media module 200, the production water is passed through flow control assembly 218. In flow control assembly 218, production water passes through primary filter 219 and secondary filter 221, for the removal of particulate matter. Once production water passes through flow control assembly 218, the production water is then pumped into the two elongated vessels 202 through water inlet 210.
Date Recue/Date Received 2020-08-14

[0034] Referring to FIG. 3, the flow of water into the two elongated vessels 202 is controlled via flow control assembly 218. The flow rate should match the ability of the adsorption media to adsorb the contaminants. This is tied to time exposure.
Referring to FIG.
2, in the proto-type, elongated vessels 202 were 25 feet long. As the production water flows through the adsorption media in the two elongated vessels 202, contaminants from the production water are adsorbed by adsorption media. De-contaminated production water then flows out water outlet 212 to de-contaminated water storage facility 500 for storage and reuse.
The flow rate was optimized by performing calculations and by testing performed at water outlet 212. If trace contaminants appear at water outlet 212, the flow rate is too high.

[0035] Referring to FIG. 2, once adsorption media in one of the two elongated vessels 202 becomes saturated with contaminants from the production water, the flow of production water through that elongated vessel 202 is stopped. Water is then pumped into the elongated vessel 202 to turn the granular adsorption media into a slurry, which can be removed through water outlet 212 using a vacuum truck.

[0036] The two elongated vessels 202 allow for alteration in operation between the two such that the process of passing production water through adsorption media can be a continual process. An operator can keep the flow of production water running through one elongated vessel 202, while replacing the saturated adsorption media with fresh adsorption media in the other elongated vessel 202. Preferably, both of the two elongated vessels 202 is operated simultaneously with a slightly offset operationschedule to allow for the time required to change out adsorption media. Doing so would provide for a continuous and high capacity operation.

[0037] Referring to FIG. 1, the process then involves a second step of subjecting adsorption media to an agitation and heat treatment at temperatures of between 650 and 850 degrees Celsius until the contaminants undergo a phase change to gaseous form. The saturated adsorption media is moved from adsorption media module 200 to the adsorption media rejuvenation module 300. Referring to FIG. 4, the saturated adsorption media is loaded into the rotary kiln 302. Once loaded into the rotary kiln 302, the rotary kiln 302 subjects the saturated adsorption media to a direct heat treatment at temperatures of between 650 and 850 degrees Date Recue/Date Received 2020-08-14 Celsius. Rotary kiln 302 agitates the saturated adsorption media through a rotary mechanism.
Referring to FIG. 1, air inlet 304 adds a controlled amount of air to rotary kiln 302 to assist with the oxidization and combustion of contaminants. As the contaminants undergo a phase change to gaseous form and are liberated from adsorption media, the gaseous contaminants are evacuated from rotary kiln 302 via gas outlet 306. Once adsorption media is fully de-contaminated via this heat and agitation treatment, adsorption media is unloaded from rotary kiln 302 and cooled to room temperature. This de-contaminated adsorption media is removed from adsorption media rejuvenation module 300 and re-loaded back into adsorption media module 200 for re-use in the de-contamination of production water.

[0038] Referring to FIG. 1, the process involves a third step of condensing the contaminants in the gaseous form to a liquid form, and capturing the contaminants in the liquid form. As the contaminants undergo a phase change to gaseous form in rotary kiln 302, the gaseous contaminants are continuously evacuated from adsorption media rejuvenation module 300 to hydrocarbon contaminants recovery module 400 by compressor 402 through gas outlet 306.
The gaseous contaminants are discharged into cooler-condenser 404 and are condensed back into liquid form. The liquefied contaminants are then captured in storage container 406. The recovered liquid contaminants in storage container 406 can then be refined and reused, sold, or disposed of safely into disposal well 600. It is important to note, that there will be no atmospheric discharge of the noxious contaminants.

[0039] In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.

[0040] The scope of the claims should not be limited by the illustrated embodiments set forth as examples, but should be given the broadest interpretation consistent with a purposive construction of the claims in view of the description as a whole.
Date Recue/Date Received 2020-08-14

Claims

What is Claimed is:

1. A process for removing contaminants from production water, comprising:
passing production water through an adsorption media in order to capture hydrocarbon contaminants;
subjecting the adsorption media to a heat treatment until the contaminants undergo a phase change to gaseous form;
condensing the contaminants in the gaseous form to a liquid form; and capturing the contaminants in the liquid form.

2. The process of Claim 1, wherein the adsorption media is a combination of activated and bio carbon adsorption media.

3. The process of Claim 1, wherein after removal of the contaminants the production water is stored in preparation for reuse.

4. The process of Claim 1, wherein the flow rate through the adsorption media is controlled.

5. The process of Claim 1, wherein the heat treatment is at temperatures of between 650 and 850 degrees Celsius.

6. The process of Claim 1, wherein the adsorption media is agitated during the heat treatment.

7. A process for removing contaminants from production water, comprising:
passing production water through an adsorption media which is a combination of activated and bio carbon at a controlled flow rate in order to capture hydrocarbon contaminants;
storing the production water for reuse after removal of contaminants;
subjecting the adsorption media to a heat treatment at temperatures of between 650 and 850 degrees Celsius until the contaminants undergo a phase change to gaseous form, the adsorption media being agitated during the heat treatment;
Date Recue/Date Received 2020-08-14 condensing the contaminants in the gaseous form to a liquid form; and capturing the contaminants in the liquid form.

8. A system for removing contaminants from production water, comprising:
an adsorption media module, comprising:
one or more elongated vessels containing an adsorption media capable of adsorbing hydrocarbons, the one or more elongated vessels having a first end, a second end, a water inlet at the first end and a water outlet at the second end, the one or more elongated vessels being in a generally horizontal orientation; and a flow control assembly for controlling a flow rate of production water through the one or more elongated vessels from the inlet to the outlet;
an adsorption media rejuvenation module, comprising:
a kiln for subjecting the adsorption media to a heat treatment until the contaminants undergo a phase change to gaseous form;
a hydrocarbon contaminants recovery module, comprising:
at least one cooler-condenser for condensing the contaminants in the gaseous form to a liquid form; and a storage container for capturing the contaminants in the liquid form.

9. The system of Claim 8, wherein the one or more elongated vessels are oriented at an oblique angle relative to a horizontal plane, with the inlet positioned above the outlet.

10. The system of Claim 9, wherein the oblique angle is between 10 and 30 degrees.

11. The system of Claim 8, further comprising a media inlet at the first end.

12. The system of Claim 8, wherein the kiln is a rotary kiln for subjecting the adsorption media to a heat treatment with agitation until the contaminants undergo a phase change Date Recue/Date Received 2020-08-14 to gaseous form.

13. The system of Claim 8, wherein at least one compressor draws contaminants in gaseous form from the kiln into the at least one cooler-condenser.

14. The system of Claim 8, wherein the one or more elongated vessels are of a non-corrosive material.

15. The system of claim 14, wherein the non-corrosive material is a high density polyethylene polymer plastic (HDPE).

16. The system of Claim 8, wherein air is supplied to the kiln.

17. The system of Claim 8, the adsorption media is a combination of activated and bio carbon adsorption media.

18. The system of Claim 8, wherein the adsorption media is in granulated form.

19. A system for removing contaminants from production water, comprising:
an adsorption media module, comprising:
one or more elongated vessels containing an adsorption media capable of adsorbing hydrocarbons, a combination of activated and bio carbon adsorption media in granulated form, the one or more elongated vessels having a first end, a second end, an inlet at the first end and an outlet at the second end, the one or more elongated vessels being in a generally horizontal orientation; the one or more elongated vessels are oriented at an oblique angle of between 10 and 30 d egrees relative to a horizontal plane, with the inlet positioned above the outlet, the one or more elongated vessels are of a non-corrosive high density polyethylene polymer plastic (HDPE); and a flow control assembly for controlling a flow rate of production water through the one or more elongated vessels from the inlet to the outlet;
an adsorption media rejuvenation module, comprising:
a rotary kiln for subjecting the adsorption media to a heat treatment with agitation until the contaminants undergo a phase change to gaseous form; and Date Recue/Date Received 2020-08-14 an sources supplies combustion air to the rotary kiln;
a hydrocarbon contaminants recovery module, comprising:
at least one compressor for drawing contaminants in gaseous form from the rotary kiln;
at least one cooler-condenser for condensing the contaminants in the gaseous form to a liquid form; and a storage container for capturing the contaminants in the liquid form.
Date Recue/Date Received 2020-08-14