A gas processing plant for an offshore platform

Abstract

This utility model discloses a gas treatment device for offshore platforms, relating to the field of gas treatment technology. It includes: a scrubber with an internal gas distribution device and wire mesh demisting packing; a natural gas inlet switch valve installed on the scrubber's inlet pipe, which connects to an upstream natural gas treatment system; coalescing filters A and B, operating in parallel, with coalescing filter A containing coalescing filter element A and coalescing filter B containing coalescing filter element B; an electric heater connected to the outlets of coalescing filters A and B; and a piping system connecting the above components. This utility model employs a parallel design for coalescing filters A and B, combined with a differential pressure transmitter to monitor the filter element status in real time, enabling online switching and standby of the filters. Filter elements can be cleaned or replaced without shutdown, ensuring continuous and stable operation of the fuel gas system.

Description

Technical Field

[0001] This utility model relates to the field of gas treatment technology, and in particular to a gas treatment device for offshore platforms. Background Technology

[0002] The process system of an offshore natural gas platform mainly includes the separation of extracted natural gas into gas, oil, and water phases by a production separator. This is followed by further separation through a natural gas processing system, a condensate processing system, and a production water treatment system, ensuring the natural gas meets pipeline transportation requirements. The processed natural gas is then transported to the onshore terminal via subsea pipelines. On-platform processing primarily involves filtration and dehydration of the natural gas. In the natural gas system, besides the majority being transported to the onshore terminal via subsea pipelines, a small portion enters a gas scrubber and gas heater. This portion of natural gas, after filtration and heating, flows into the fuel gas pipeline and is delivered to various users on the platform, including gas generator sets, high and low pressure flare heads, and triethylene glycol regeneration systems. A portion of the natural gas is processed by the platform's purification equipment for daily use, i.e., the fuel gas system. The main uses of fuel gas are: providing fuel for boilers, converting combustion heat into thermal energy; providing fuel for turbine engines, converting combustion heat into electrical energy; and providing fuel for turbine-driven compressors, converting combustion heat into kinetic energy to compress gas.

[0003] Because offshore platforms are located far from land, they generally do not utilize existing onshore power or heat sources, typically relying on their own on-board power generation or heating to achieve self-sufficiency. Natural gas produced by offshore oil and gas exploration platforms can be processed and used as fuel, making it both convenient and inexpensive for offshore platforms, thus becoming their primary fuel.

[0004] The natural gas extracted from the platform contains certain impurities, which can affect its usability. The main hazards of solid and liquid impurities in natural gas are as follows: Solid particulate contaminants in natural gas not only increase pipeline resistance and reduce the quality of gas transmission pipelines, but also cause severe erosion of metals, leading to pipeline rupture. Simultaneously, they affect the normal operation of equipment, valves, and instruments, accelerating the wear and shortening the service life of compressor and gas turbine blades. Liquid water and hydrocarbons easily condense when the temperature decreases, restricting the flow of natural gas in the pipeline, reducing the gas transmission rate, and in severe cases, forming ice blockage. Moreover, liquid water mixed with carbon dioxide or hydrogen sulfide forms corrosive acids that corrode metals, causing large-area thinning of pipe walls or localized pitting corrosion, leading to equipment corrosion and cracking. Therefore, separating solid particles and droplets entrained in natural gas to improve its quality is particularly important.

[0005] Fuel gas has certain quality requirements, including: high calorific value; no free water; 99% of solid particles must be less than 10 μm in diameter; the maximum diameter of liquid hydrocarbon particles must be less than 10 μm; the dew point of the fuel gas should be lower than the supply temperature, and it is required that no hydrates or other solid or semi-solid hydrocarbons will form in the gas when the temperature drops; the supply temperature range of the fuel gas should be 0-65℃ (or other specified temperature range).

[0006] Problems with current fuel gas processing technology:

[0007] 1) The fuel gas heater is designed upstream of the pressure reducing valve, and there is no gas scrubber designed at the outlet of the heater, so it is impossible to remove the condensate generated by the fuel gas treatment system under changing operating conditions.

[0008] 2) The fuel gas filter is designed for independent use by a single unit and cannot be switched between units. In special cases where the generator set must be switched first if the filter needs to be replaced or cleaned, the FM unit cannot use gas normally.

[0009] 3) After being heated by the heater, the fuel gas is directly sent to the heat medium boiler, where it is depressurized and supplied to the boiler. The condensate produced due to the change in operating conditions makes it very difficult for the boiler to ignite in gas mode. Utility Model Content

[0010] This utility model provides a gas treatment device for offshore platforms, which can solve the problem in the prior art where the fuel gas heater is designed upstream of the pressure reducing valve and there is no gas scrubber designed at the outlet of the heater, making it impossible to remove the condensate generated by the fuel gas treatment system under changing operating conditions.

[0011] The objective of this utility model can be achieved through the following technical solutions:

[0012] A gas treatment device for offshore platforms, comprising:

[0013] The scrubber is equipped with a gas distribution device and a wire mesh demisting packing.

[0014] A natural gas inlet switch valve is installed on the inlet pipe of the scrubber, which is connected to the upstream natural gas processing system.

[0015] Coalescing filter A and coalescing filter B are connected in parallel. Coalescing filter A is equipped with coalescing filter element A, and coalescing filter B is equipped with coalescing filter element B.

[0016] An electric heater is connected to the outlets of coalescing filter A and coalescing filter B.

[0017] As a further embodiment of this utility model: the top of the scrubber is provided with a scrubber pressure transmitter and a scrubber pressure regulating valve for adjusting the natural gas pressure.

[0018] As a further embodiment of this utility model: the bottom of the washer is provided with an washer level transmitter, an washer level regulating valve, and an washer level switching valve for controlling the liquid level inside the washer.

[0019] As a further embodiment of this utility model: the coalescing filter A is provided with a coalescing filter A level transmitter and a coalescing filter A level regulating valve; the coalescing filter B is provided with a coalescing filter B level transmitter and a coalescing filter B level regulating valve.

[0020] As a further embodiment of this utility model: both coalescing filter A and coalescing filter B are provided with safety relief pipes at their tops. The safety relief pipes are connected to relief port D. A safety valve for coalescing filter A is installed on the safety relief pipe located above coalescing filter A, and a safety valve for coalescing filter B is installed on the safety relief pipe located above coalescing filter B.

[0021] As a further embodiment of this utility model: both the coalescing filter element A and the coalescing filter element B have a multi-layer structure. The innermost layer is a stainless steel inner skeleton support layer, the middle layer is a multi-pleated glass fiber coalescing layer, the coalescing layer is composed of multiple layers of glass fibers with gradually increasing filter pore diameter, and the outer layer is a drainage layer.

[0022] As a further embodiment of this invention, the surface of the coalescing filter element is provided with a fluoride coating.

[0023] As a further embodiment of this utility model: an electric heater inlet temperature transmitter and an electric heater outlet temperature transmitter are installed on the inlet and outlet pipes of the electric heater, and the electric heater controller automatically adjusts the heating power according to the temperature difference.

[0024] As a further embodiment of this utility model: the outlet pipe of the electric heater is equipped with a fuel gas flow meter for measuring the flow of natural gas exported.

[0025] As a further aspect of this utility model: the switching between coalescing filter A and coalescing filter B is achieved by detecting the filter element blockage status through a differential pressure transmitter. When the inlet and outlet differential pressure of one of the coalescing filters is greater than 300 kPa, the filter is switched to the other coalescing filter.

[0026] The beneficial effects of this utility model are:

[0027] (1) The coalescing filters A and B are designed in parallel and are used in conjunction with a differential pressure transmitter to monitor the filter element status in real time, so as to realize online switching and standby of the filters. The filter element can be cleaned or replaced without stopping the machine, ensuring the continuous and stable operation of the fuel gas system.

[0028] (2) Through the built-in gas distribution device and wire mesh demisting packing, small droplets and particles in natural gas are effectively removed, significantly improving the cleanliness of natural gas and reducing corrosion and wear inside pipelines and equipment.

[0029] (3) Through the gas distribution device and wire mesh demisting packing in the scrubber, combined with the multi-layer filter element structure of the coalescing filter, solid particles, droplets and condensate in natural gas can be removed efficiently, ensuring that the fuel quality meets the requirements and avoiding problems such as equipment corrosion, pipeline blockage and unstable combustion.

[0030] (4) Through the level transmitters, pressure regulating valves and safety relief valves of the scrubber, coalescing filter and electric heater, the system pressure and level are monitored and automatically adjusted in real time. Combined with the relief port and closed drainage system, the risk of overpressure is effectively prevented, and the safety and stability of the equipment are ensured. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] Figure 1 This is a structural schematic diagram of a gas treatment device for offshore platforms according to this utility model.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Natural gas inlet switch valve; 2. Scrubber; 3. Gas distribution device; 4. Wire mesh demister packing; 5. Scrubber pressure transmitter; 6. Scrubber pressure regulating valve; 7. Scrubber level transmitter; 8. Scrubber level regulating valve; 9. Scrubber level switch valve; 10. Scrubber safety valve; 11. Coalescing filter A; 12. Coalescing filter B; 13. Coalescing filter element A; 14. Coalescing filter element B; 15. Coalescing filter A level transmitter; 6. Coalescing filter B level transmitter; 17. Coalescing filter A level control valve; 18. Coalescing filter B level control valve; 19. Coalescing filter A safety valve; 20. Coalescing filter B safety valve; 21. Coalescing filter differential pressure transmitter; 22. Electric heater; 23. Electric heater inlet temperature transmitter; 24. Electric heater outlet temperature transmitter; 25. Electric heater controller; 26. Electric heater safety valve; 27. Fuel gas flow meter. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] In the description of this utility model, it should be understood that the terms "upper," "lower," "left," and "right," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on this utility model. Furthermore, "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "multiple" means two or more.

[0037] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0038] Please see Figure 1 As shown, this utility model is a gas processing device for offshore platforms, comprising:

[0039] The scrubber 2 is equipped with a gas distribution device 3 and a wire mesh demisting packing 4;

[0040] Natural gas inlet switch valve 1 is installed on the inlet pipe of scrubber 2, which is connected to the upstream natural gas processing system.

[0041] Coalescing filter A11 and coalescing filter B12 operate in parallel. Coalescing filter A11 is equipped with coalescing filter element A13, and coalescing filter B12 is equipped with coalescing filter element B14.

[0042] An electric heater 22 is connected to the outlets of coalescing filters A11 and B12.

[0043] Natural gas from the processing system undergoes pretreatment such as dehydration, decarbonization, and desulfurization before being transported via pipeline to the fuel gas processing unit. It then enters the scrubber 2 via the natural gas inlet valve 1. The natural gas inlet valve 1 can be opened and closed as needed. It opens when fuel gas replenishment is required and closes when no fuel gas replenishment is needed or in case of an emergency preventing fuel gas supply. The scrubber 2 is typically a vertical tank. A gas distribution device 3 is installed at the fuel inlet pipeline connection to evenly distribute the natural gas entering the scrubber 2 radially, preventing gas short-circuiting. At the top of the scrubber 2, a wire mesh demister packing 4 is installed. Natural gas from the gas distribution device 3 flows upwards and passes through the wire mesh demister packing 4, removing small droplets and particles, thus purifying the natural gas. A pressure transmitter 5 is installed at the top of the scrubber 2 near the wire mesh demisting packing 4 to indicate the natural gas pressure in real time. A pressure regulating valve 6 is installed on the branch pipe of the natural gas outlet pipeline. The opening of the pressure regulating valve 6 is adjusted according to the pressure indication of the pressure transmitter 5 to keep the natural gas pressure within the required controllable range. Small droplets separated from the scrubber 2 collect at the bottom of the scrubber 2 to form a liquid layer. A liquid level transmitter 7 is installed at the bottom of the scrubber 2 to indicate the liquid level in real time. A liquid discharge pipe is installed at the bottom of the scrubber 2, and a liquid level regulating valve 8 and a liquid level switch valve 9 are installed on the liquid discharge pipe. The opening of the liquid level regulating valve 8 can be adjusted according to the liquid level indication of the liquid level transmitter 7 to keep the liquid level at the bottom of the scrubber 2 at a suitable position. A safety relief pipe and a safety valve 10 are installed at the top of the scrubber 2 to ensure that the entire fuel gas system does not overpressure.

[0044] Natural gas flows from the top net outlet pipe of scrubber 2 to coalescing filters A11 and B12, which are respectively equipped with coalescing filter elements A13 and B14. The coalescing filters are typically vertical, consisting of upper and lower sections. Gas first enters the lower primary cyclone separator through the inlet, where large droplets larger than 300μm are separated by sedimentation. The gas then flows upward through the tube sheet to the upper secondary coalescing zone. After flowing from the inside of the coalescing filter element to the outside, the gas exits through the top outlet. The coalescing filter element has a multi-layered structure. The innermost layer is a stainless steel inner skeleton support layer, the middle layer is a multi-pleated glass fiber coalescing layer composed of multiple layers of glass fiber with gradually increasing pore diameters. The outermost layer is a drainage layer, and the outermost layer usually has an outer skeleton to meet the strength requirements of the coalescing filter element. The gas-liquid coalescing filter element has a higher efficiency in removing droplets. The cumulative efficiency for 0.3μm droplets is over 99.8%; the cumulative efficiency for 1μm droplets is 99.99%. Unlike direct interception and inertial impaction interception, this method utilizes micropores to intercept droplets in the airflow. Therefore, the coalescing filter separator's separation efficiency increases as the gas flow rate decreases. It also boasts high filtration accuracy, excellent separation effect, low equipment cost, and small footprint, making it a superior choice for removing entrained droplets from natural gas. A fluorinated emulsion is used as a treatment agent to surface-treat the entire filter element, forming a thin fluorinated coating on the filter media surface. This coating provides both oleophobic and hydrophobic properties, effectively reducing the surface energy of the coalescing medium, preventing liquid from wetting the entire coalescing medium fiber, and ensuring effective coalescing. Simultaneously, it accelerates the drainage rate, ensuring that liquid only drains from the bottom of the filter element. In untreated filter elements, liquid drains from the entire filter element. Both chemically treated and untreated filter elements offer the following advantages: better coalescing effect, larger flow rate, smaller equipment size, longer lifespan, and lower pressure drop. Generally, chemically treated filter cartridges have a service life of 1-2 years due to their anti-fouling ability, while untreated filter cartridges typically have a service life of no more than 0.5 years.

[0045] Fine droplets in the natural gas accumulate at the bottom of coalescing filters A11 and B12, forming a liquid layer. Coalescing filter A level transmitter 15 and coalescing filter B level transmitter 16 are installed at the lower part of coalescing filters A11 and B12, respectively. Coalescing filter A level regulating valve 17 and coalescing filter B level regulating valve 18 are installed on their drain pipes, respectively. Based on the level setpoints of coalescing filter A level transmitter 15 and coalescing filter B level transmitter 16, the opening of coalescing filter A level regulating valve 17 and coalescing filter B level regulating valve 18 is adjusted to ensure that the liquid level in coalescing filters A11 and B12 is maintained at a suitable position. Safety relief pipes and coalescing filter A safety valve 19 and coalescing filter B safety valve 20 are installed at the top of coalescing filters A11 and B12 to ensure that the entire fuel gas system does not overpressure.

[0046] Coalescing filters A11 and B12 operate in parallel. Depending on the opening and closing of their respective manual or automatic inlet and outlet valves, when coalescing filter A11 is running, coalescing filter B12 is on standby; conversely, when coalescing filter A11 is on standby, coalescing filter B12 is running. The operation and standby status are indicated by the differential pressure indication of the coalescing filter differential pressure transmitter 21. Generally, when the inlet and outlet differential pressure of the coalescing filter exceeds 300 kPa, it indicates that the coalescing filter element needs cleaning, and in this case, it is necessary to switch to the standby coalescing filter.

[0047] After being dehumidified and having solid impurities removed by the coalescing filter, the natural gas exits the coalescing filter at the top and proceeds to the subsequent electric heater 22. An inlet temperature transmitter 23 and an outlet temperature transmitter 24 are installed on the pipeline connecting the natural gas to and from the electric heater 22. Based on the temperature difference between the inlet and outlet temperature transmitters 23 and 24, the electric heater controller 25 automatically adjusts the heating power of the electric heater 22 to ensure that the natural gas temperature meets the subsequent usage temperature requirements, i.e., the outlet temperature transmitter 24 meets the set requirements. A fuel gas flow meter 27 is also installed on the outlet pipeline of the electric heater 22 for measuring the exported natural gas. The outlet of the fuel gas flow meter 27 is connected to the fuel gas port E leading to the subsequent usage unit.

[0048] The electric heater 22 is equipped with a safety relief pipe and an electric heater safety valve 26 on top to ensure that the entire fuel gas system does not overpressure. When the system differential pressure needs to be safely released, the released gas is combined with the released gas from the scrubber safety valve 10, the released gas from the coalescing filter A safety valve 19 and the coalescing filter B safety valve 20 and connected to the release port D.

[0049] Each of the above components is connected to a drain pipe at its bottom. The drain pipe is connected to drain port F, which is connected to an external closed-loop drainage system.

[0050] The above description provides a detailed account of one embodiment of the present invention. However, this description is merely a preferred embodiment and should not be construed as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the claims of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A gas processing device for offshore platforms, characterized in that, include: The washer (2) is equipped with a gas distribution device (3) and a wire mesh demisting packing (4). Natural gas inlet switch valve (1) is installed on the inlet pipe of the scrubber (2), which is connected to the upstream natural gas processing system; Coalescing filter A (11) and coalescing filter B (12) are connected in parallel. Natural gas is delivered to coalescing filter A (11) and coalescing filter B (12) through the net outlet pipe at the top of the scrubber (2). Coalescing filter A (11) is equipped with coalescing filter element A (13), and coalescing filter B (12) is equipped with coalescing filter element B (14). An electric heater (22) is connected to the outlets of coalescing filter A (11) and coalescing filter B (12).

2. The gas treatment equipment for offshore platforms according to claim 1, characterized in that, The top of the scrubber (2) is equipped with a scrubber pressure transmitter (5) and a scrubber pressure regulating valve (6) for regulating the natural gas pressure.

3. The gas treatment equipment for offshore platforms according to claim 1, characterized in that, The bottom of the washer (2) is provided with a washer level transmitter (7), a washer level regulating valve (8) and a washer level switching valve (9) for controlling the liquid level inside the washer (2).

4. A gas treatment device for offshore platforms according to claim 1, characterized in that, The coalescing filter A (11) is equipped with a coalescing filter A level transmitter (15) and a coalescing filter A level regulating valve (17); the coalescing filter B (12) is equipped with a coalescing filter B level transmitter (16) and a coalescing filter B level regulating valve (18).

5. A gas treatment device for offshore platforms according to claim 1, characterized in that, Both coalescing filter A (11) and coalescing filter B (12) are provided with safety relief pipes at the top. The safety relief pipes are connected to the relief port D. A safety valve (19) for coalescing filter A is installed on the safety relief pipe above coalescing filter A (11), and a safety valve (20) for coalescing filter B is installed on the safety relief pipe above coalescing filter B (12).

6. A gas treatment device for offshore platforms according to claim 1, characterized in that, Both the coalescing filter element A (13) and the coalescing filter element B (14) have a multi-layer structure. The innermost layer is a stainless steel inner skeleton support layer, the middle layer is a multi-fold glass fiber coalescing layer, the coalescing layer is composed of multiple layers of glass fiber with gradually increasing filter pore diameter, and the outer layer is a drainage layer.

7. A gas treatment device for offshore platforms according to claim 6, characterized in that, The surface of the coalescing filter element is coated with a fluoride.

8. A gas treatment device for offshore platforms according to claim 1, characterized in that, The electric heater (22) is equipped with an electric heater inlet temperature transmitter (23) and an electric heater outlet temperature transmitter (24) on the inlet and outlet pipes. The electric heater controller (25) automatically adjusts the heating power according to the temperature difference.

9. A gas treatment device for offshore platforms according to claim 1, characterized in that, The outlet pipe of the electric heater (22) is equipped with a fuel gas flow meter (27) for measuring the output natural gas.

10. A gas treatment device for offshore platforms according to claim 1, characterized in that, The switching between coalescing filter A (11) and coalescing filter B (12) is achieved by detecting the filter element blockage status through differential pressure transmitter (21). When the inlet and outlet differential pressure of one of the coalescing filters is greater than 300 kPa, the filter is switched to the other coalescing filter.

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