PROCESS FOR THE REMOVAL OF H2S FROM SOUR GAS WHILE LIMITING SCAVENGING CHEMICALS

Abstract

An H.sub.2S stripper that utilizes random packing material in the center column to greatly increase the conversion of H.sub.2S gas to a solid form of sulfur. A thin film of scrubbing solution coating the packing material allows for a more efficient process of H.sub.2S scrubbing that can reduce the chemical consumption rates of traditional, commercially available sulfide scavengers by 25 to 60%. This unit also allows for an easy clean out and is built to handle the pressure extremes that could be encountered in oil wells and/or gas wells, gas plants, offshore rigs, gas gathering systems, or pipe lines while not having any mechanical parts. This invention improves the H.sub.2S removal process and reduces the amount of H.sub.2S in natural gas streams as well as reducing the amount of treating chemicals.

Claims

1. A process for the removal of H.sub.2S from a gas stream containing H.sub.2S enclosed in a steel vessel, includes the following: a) a solution of scrubbing chemical, and b) random packing material.

2. The scrubbing solution described in claim 1 includes, but is not limited to, triazine, the current industry standard for H.sub.2S scrubbing, any other or newly developed scrubbing solution can be applied to the process in claim 1.

3. A process, in accordance with claim 1 may contain any gas stream which has H.sub.2S present that needs to be removed by a reactor or any type of vessel acting as a reactor that is filled a packing material that is coated in a scrubbing chemical solution.

4. The packing material, in accordance with claims 1 and 3 may be of any material, including but not limited to ceramic, plastic, or a metal.

5. The process, described in claim 1 may have any type of flow entering the reactor vessel. The flow profile may be either laminar or turbulent in nature.

6. The packing material in claim 3 and claim 5 creates a turbulent type flow even for the laminar fluids and drives the gas into the liquid interface at the surface of the packing material.

7. The process in accordance to claim 1, drives the conversion reaction between the H.sub.2S and the scrubbing solution. The greater the surface area of the packed material, the more favorable the reaction.

8. The process, described in claim 7, will result in the decrease in the amount of scrubbing material needed for the removal of H.sub.2S from the gas stream. The reduction of scrubbing chemicals is reduced by 25 to 60%.

9. The reduction in scrubbing chemicals, described in claim 8, is tied directly to the size of the reactor equipment, resulting in a reduction of reactor size, generally by the same percentage of the reduction of scrubbing chemicals, 25 to 60%.

10. The process in accordance with claim 1 reduces the amount of H.sub.2S from a standard natural gas stream from an oil and/or gas well by at least 95%.

Description

DRAWING DESCRIPTIONS

[0018] FIG. 1 is a schematic of the invention for the process of the removal of H.sub.2S from the natural gas stream. FIG. 1 is a single tube/vessel packed reactor.

DETAILED DESCRIPTION OF THE INVENTION

[0019] This invention is different from those previously patented and in the market today. This will be made clear in this section, based on previous sections and what is claimed in this patent. While slight modification may be made or constructed to change the described invention, this patent should be taken as a guideline and anything created within the spirit or the scope of this invention should fall under this patent. The description and drawings should be understood as an illustration of one example of the said invention in is not the sole, limiting case. Let it be known that the claims and illustration are a generic example of the invention and the language and description used to describe the invention are not limiting.

[0020] Referring to FIG. 1, the reactor for the process of stripping H.sub.2S from natural gas. Natural gas from the gas lines enters the bottom of the reactor, 1. The natural gas can have any concentration of H.sub.2S and CO.sub.2 in it, along with other gasses commonly found in natural gas streams. The natural gas can have any type of flow rate, and with that a corresponding turbulent or laminar flow, for the said invention to work. The reaction vessels are custom made for specific applications and any pressure may be used that are commonly seen in the oil and gas industry.

[0021] Along with the natural gas entering the reactor from the gas line, labeled 1, the scrubbing chemical also enters the reaction vessel from this line. There are multiple ways to accomplish this task of getting a liquid droplet of chemical into a gas stream, including using an atomizer to emit either a fine mist spray continuously or intermittently, another is to slowly drip small amounts of chemical into the gas stream and allow the gas to pick up the liquid as it is passing by on the way to the reaction vessel. Other possibilities exist, but that is not the scope of this invention.

[0022] Referring to the pressure tested common steel reactor, 2, the reactor may be made from a long pre-ordered tube or a custom made welded tube manufactured for the specific application. This pressure tested common steel reaction vessel can be made of any thickness, to meet the pressure and flow rate demands of the application, generally the steel is constructed from J-55 or L-80 grade steel. The thickness of the steel vessel is dependent upon the specifications of the oil and/or gas well as defined by the ASME code. The outer diameter (O.D.) of the vessel can also be adapted based on the concentration of H.sub.2S and the flow rate of natural gas, but generally it must be at least 4 inches in O.D. to accommodate the random packing materials and to ensure that there is not sufficient pressure drop in the reactor. The height of the reactor is also dependent on the application. For a single natural gas well, the vessel may only be 1 to 2 feet tall, for larger applications, the vessel may need to 4 to 7 feet tall. The diameter can also be widened to keep costs of fabrication and transport to a minimum.

[0023] The reaction vessel, 2, along with the contents inside of the reactor, are coated with a thin film of the scrubbing chemical, depicted in FIG. 1 as the dark gray shading, 3 around the random packings, 4. The scrubbing liquid reacts with the H.sub.2S. The scrubbing liquid is commercially bought. The industry standard at the present time of the invention is triazine. While more modern scrubbers are surely being developed by other companies, this invention could use those that are being developed after testing for material and safety compatibility. The amount of scrubbing solution is dependent upon the conditions of the individual well, based on H.sub.2S and the flow rate of gas, along with the packings that are used. With a higher surface area packing, it will take more liquid to coat all of the surfaces with a thin, reactive film of the scrubbing solution. To use the scrubbing solution, follow the commercially approved guidelines from the supplier that you purchase the solution from. Just note that if you are using current methods you will be using more solution than you would be using if you are using this invention, this invention decreases your solution requirements by 25 to 60%.

[0024] The random packings, 4, are installed when the reaction vessel, 2 is constructed. The random packings are completely filling the vessel. The random packing materials are purchased from commercial suppliers, one such supplier is Koch-Glitsch that are commonly found in separation columns. The materials can be either plastic, ceramic or metal, depending on user preference, costs, components of natural gas, and temperatures. To keep costs and shipping weight down, plastics have been used very successfully in most applications. The random packings also allow the flow rate of natural gas from the input stream, 1, to be either a laminar or turbulent flow, because the flow around the random packings create eddies, causing any laminar flow to exhibit a turbulent flow like profile. The size of the random packings is also dependent on the application. In our trial tests, we have seen that random packing from ¾ to 1 inch work very well, as long as they have a fairly hollow design, much like the FLEXIRING® that Koch-Glitsch produces and sells commercially.

[0025] The benefit of the random packings, 4, and how random packing improves the H.sub.2S removal process is the random packing generates a much higher surface area for the reaction to take place. By spreading the scrubbing solution, 3, over the random packing material to create a thin film of the reactive solution and forcing the gas to flow on and over the random packing creates a much more favorable environment for the reaction to take place. By increasing this surface area and making for a much richer environment for the reaction, less of the scrubbing liquid is required for the reaction. This in turn, makes the reaction vessel, 2, to be smaller as well.

[0026] After the natural gas has been forced past all of the random packing material, 4, the natural gas exits the reaction vessel, 2, through a port at the top, 5. The natural gas exiting the reactor can then be shipped or sold to gas processing plants. However, this natural gas will be reduced of H.sub.2S. It has been common to see H.sub.2S in the exiting natural gas streams to be more than 95% less than the entering stream, in some applications, H.sub.2S has been virtually undetectable, meaning that this process removes most, if not all of the H.sub.2S from the natural gas stream. All while using much less scrubbing solution, 3.