PSA (Pressure Swing Adsorption) device with long operation period and operation method thereof

Abstract

The invention relates to the technical field of PSA hydrogen purification, and discloses a long-operation-cycle PSA device and an operation method thereof.The device comprises a feeding buffer part communicated with feed gas, an adsorption part communicated with the feeding buffer part, and a product gas buffer part and a desorption gas buffer part which are communicated with the adsorption part; the feeding buffer part comprises a tank body, a liquid separation adsorption part arranged in the tank body and a baffle plate for changing the flow direction of gas at a feeding hole; the liquid separation adsorption part comprises an adsorption part and a liquid separation part arranged on the adsorption part in a sleeving manner; according to the device, an adsorbent and a vapor-liquid separation part are coupled in the feeding buffer part, so that the technical effect of simultaneously separating liquid heavy hydrocarbon and crystalline salt is realized; meanwhile, the structures of the adsorption part, the gas-liquid part and the buffer tank body are optimized, so that raw material gas with high content of crystalline salt and liquid heavy hydrocarbon can be treated; and the device is also provided with a washing part at the adsorption part, so that the production continuity is ensured, the crystal salt in the adsorption part is treated, and the operation cycle of the PSA device is obviously prolonged.

Description

Technical Field

[0001] This invention relates to the field of PSA hydrogen purification technology, and in particular to a long-cycle PSA device and its operation method. Background Technology

[0002] There are four main methods for purifying petrochemical gases: cryogenic separation, membrane separation, chemical absorption, and adsorption separation. Pressure swing adsorption (PSA) has rapidly developed due to its advantages such as high product purity, short process flow, strong applicability to feed gas, high operational flexibility, simple product purity adjustment and operation, and low energy consumption and operating costs, becoming the main process for purifying gases in oil refining and chemical enterprises. For PSA hydrogen purification, the strong applicability to feed gas is one of the advantages of this process. However, the complexity and diversity of feed gas, and the accumulation of trace impurities such as chlorine, ammonia, and trace amounts of gaseous water in the feed gas over a period of time, can clog the bottom distributor of the adsorption tower and some adsorbent channels, thereby causing an increase in the pressure drop of the adsorption tower bed and affecting the normal operation of the PSA unit. Furthermore, during the vacuuming process, some impurities enter the vacuum pump, making the vacuum pump water environment acidic and accelerating the corrosion of vacuum pump system equipment and pipelines.

[0003] To address the aforementioned issues, existing technologies often incorporate pretreatment devices at the upstream end of the PSA unit to pretreat the feed gas. This pretreatment removes crystalline salts and liquid heavy hydrocarbons from the feed gas, preventing them from adhering to the adsorbent in the PSA unit's adsorption tower and causing blockage of the micropores responsible for adsorption. This ensures the lifespan and adsorption performance of the adsorbent in the PSA unit's adsorption tower, improving the operational economy of the PSA unit. For example, CN216440254U discloses a feed gas pretreatment system for a PSA unit. This system uses an adsorbent in a filter to remove crystalline salts from the feed gas and a coalescer to separate liquid heavy hydrocarbons from the feed gas.

[0004] The present invention found that the above-mentioned devices have the following problems: (1) The activated carbon adsorbent in the filter mainly passes through the adsorbent axially with all components of the raw gas, resulting in a small cross-sectional area through the adsorbent and easy increase of differential pressure; (2) The filter and coalescer are arranged in series, resulting in a large footprint and large process pressure drop; (3) The existing raw gas pretreatment method can only remove some of the crystalline salts in the raw gas. The remaining crystalline salts will continue to enter the bottom of the adsorption tower. With the accumulation of time, it will also affect the operation of the adsorbent and the adsorption bed. The pressure drop of the adsorption bed will continue to rise, which will affect the normal operation of the device. The current conventional method is to remove the adsorbent and replace part or all of the adsorbent at the bottom of the adsorption tower, which is costly and generates a large amount of solid waste; (4) In the pressure swing adsorption device, the vacuum desorption will bring some crystalline salts or acidic substances to the vacuum pump system. The crystalline salts and acidic substances will cause the vacuum pump system to generate an acidic environment. The acidic environment will accelerate the corrosion of equipment and pipelines. The corrosion will cause equipment damage. Air will enter the vacuum system from the equipment leakage point, causing safety hazards. Summary of the Invention

[0005] This invention addresses the problems of existing PSA pretreatment devices, such as small adsorbent cross-sectional area, large footprint due to series connection, large pressure difference, high pressure drop, and high cost for processing feed gas with high crystalline salt content. It provides a long-cycle PSA device and its operating method. This device achieves the technical effect of simultaneously separating liquid heavy hydrocarbons and crystalline salts by coupling the adsorbent and gas-liquid separator in the feed buffer section. Furthermore, the optimized structure of the adsorbent, gas-liquid separator, and buffer tank significantly increases the gas flow area, adsorbent capacity, and liquid heavy hydrocarbon separation efficiency, significantly extending the PSA device's operating cycle. It can handle feed gas with high crystalline salt and liquid heavy hydrocarbon content, significantly improving production efficiency and reducing production costs.

[0006] The specific technical solution of this invention is as follows: A long-cycle PSA unit includes a feed buffer section connected to the feed gas, an adsorption section connected to the feed buffer section, and a product gas buffer section and a desorption gas buffer section connected to the adsorption section. The feed buffer section includes a tank, a liquid-separating adsorption element disposed in the tank, and a baffle plate for changing the gas flow direction at the feed inlet. The liquid-separating adsorption element includes an adsorption element and a liquid-separating element sleeved on the adsorption element.

[0007] This invention provides a long-cycle PSA device, which is equipped with a feed buffer section to pre-treat the feed gas. The feed buffer section integrates the activated carbon filter and liquid heavy hydrocarbon coalescer in the prior art into a liquid separation adsorption element, so as to pre-separate the crystalline salt and liquid heavy hydrocarbon in the feed gas in one device, thereby reducing the footprint of the device and improving the processing efficiency.

[0008] Furthermore, this invention optimizes the structure of the liquid-liquid adsorption element. Traditional pretreatment structures consist of axially arranged activated carbon or demisters, where the raw gas is processed axially. During axial processing, the content of substances adsorbed by the adsorbent or demister inside the axial direction is different. The adsorbent or demister at the beginning end adsorbs the most adsorbable substances in the raw gas. This leads to the adsorbent or demister at the beginning end being quickly blocked by crystalline salts, resulting in the ineffective utilization of the adsorption at the end, which in turn increases the pressure drop and reduces the adsorption efficiency. Therefore, to solve the above problems, this invention designs a liquid-separating adsorption element, which includes an adsorption element and a liquid-separating element sleeved on the adsorption element. The adsorption element is composed of a defoaming mesh layer and an adsorbent layer. The liquid-separating adsorption element of this invention can process the raw gas simultaneously in both radial and axial directions after it enters. After the raw gas enters, the water and liquid heavy hydrocarbons in the raw gas first enter the liquid-separating element and are separated by the liquid-separating element. The other light hydrocarbons and hydrogen continue to enter the adsorbent layer to adsorb the crystalline salt. The cross-sectional area through which the radial airflow passes is significantly larger than the cross-sectional area through which the axial airflow passes, which allows a large flow of raw gas to pass through the activated carbon layer at a low speed. The effect of raw gas treatment is significantly increased. The radial space can maximize the utilization of the effective space volume under the premise of small pressure drop.

[0009] When the feed gas enters the buffer tank, the high-speed airflow will directly impact the liquid separator, resulting in uneven airflow distribution in the liquid separator, reducing the oil-water separation effect of the liquid separator, and making it difficult for water and liquid heavy hydrocarbons to condense into droplets. Setting up baffles to change the airflow direction can allow the feed gas to enter the liquid separator slowly and steadily, so that water and heavy hydrocarbons can effectively condense into droplets.

[0010] Preferably, the adsorption element is a hollow frustum with a thickness that gradually decreases from top to bottom, and the liquid distribution element is a hollow frustum with a thickness that gradually increases from top to bottom. The thickness of the adsorption element is 200-250 mm, and the thickness of the liquid distribution element is 200-250 mm.

[0011] The hollow part of the adsorption element is also provided with a wire mesh element, and the adsorption element is sleeved on the wire mesh element. The liquid separation element includes a support plate, a blade separator provided on the support plate, and a collection groove provided on the support plate grid. The angle between the blade separator and the central axis of the adsorption element is 105-135°, and the blade is a wedge-shaped liquid separator.

[0012] This invention further optimizes the structure of the adsorbent by setting it as a hollow frustum with gradually decreasing thickness from top to bottom, and a hollow frustum with gradually increasing thickness from top to bottom. After the liquid separator is fitted onto the adsorbent, a hollow cylinder is formed. After the raw gas passes through the baffle and changes its airflow direction, the gas gradually fills the cavity from bottom to top. Therefore, the raw gas at the bottom has the highest content of water and liquid heavy hydrocarbons. Thus, the thicker area at the bottom of the liquid separator is more conducive to the separation of raw gas with high water and liquid heavy hydrocarbon content. The content of water and liquid heavy hydrocarbons in the raw gas gradually decreases from bottom to top. Therefore, the liquid separator at the top can be set with a smaller area to efficiently separate raw gas with lower water and heavy hydrocarbon content. Furthermore, the above structure can further increase the capacity of the adsorbent and improve its operation in the later stages. At the same time, the interface formed between the adsorbent and the liquid separator is significantly increased, which can significantly increase the cross-sectional area of ​​gas passing through the adsorbent and improve the pretreatment efficiency. In addition, the present invention also found that when the moisture in the raw gas comes into contact with the surface of the adsorbent, it will dissolve the crystalline salt on the surface of the adsorbent, ensuring that the bottom of the adsorbent will not be blocked by condensation of crystalline salt. This allows the feed buffer section to have a long operating cycle when processing raw gas with high salt content and will not fail quickly.

[0013] This invention sets the blade separator of the liquid separator as a wedge-shaped liquid separator to increase the gas-liquid separation efficiency. By changing the angle of the blade separator, the droplets gathered on the blade can slide down and gather under the action of gravity, which can quickly separate the droplets from the blade separator, provide a position for subsequent gas-liquid exchange, and increase the exchange efficiency.

[0014] Preferably, the adsorption unit includes an adsorption tank and an adsorption layer disposed in the adsorption tank. The adsorption layer includes an activated carbon adsorption layer and a mixed adsorbent layer disposed on the activated carbon adsorption layer. An auxiliary water-washing magnetic ball layer is provided at the bottom of the activated carbon layer, and an isolation net is provided between the activated carbon layer and the auxiliary water-washing magnetic ball layer.

[0015] The present invention also provides an auxiliary water-washing magnetic ball layer in the adsorption section, which can avoid the interference of water on the adsorbent during water washing.

[0016] Preferably, the adsorption section is also connected to the vacuum section and the water washing section, the vacuum section is connected to the desorption section, the vacuum section is a water ring vacuum pump, and the water washing section includes a water metering tank, a water pump and a condensate drainage system.

[0017] Preferably, the vacuum unit is also connected to the neutralization injection unit, which includes a water metering tank, a water injection pump, a condensate drainage system, and a pH detection device.

[0018] A method for operating the above-mentioned long-cycle PSA device includes the following steps: (1) Hydrogen purification: The raw material gas of 1.6MPa to 1.9MPa is passed into the feed buffer section for pretreatment to obtain pretreated gas. The pretreated gas is then passed into the adsorption tower for pressure swing adsorption to produce product gas. After the product gas is stabilized by the product gas buffer tank, it enters the product gas system for later use. (2) Adsorption section regeneration: The desorption gas is drawn into the desorption gas buffer tank using the vacuum pumping section. The neutralization aid section, which is connected to the vacuum pumping section, detects the pH in the vacuum pump and injects neutralizing agent to maintain the pH of the vacuum pumping section at 6 to 7.5. (3) Adsorption section water washing: After replacing the adsorption section with nitrogen, the adsorption section is washed with water. After washing, the cleaning water is removed and the remaining moisture is purged with nitrogen. First, nitrogen is replaced, then hydrogen is purged. Gas is injected at the top and a flare system is set at the bottom.

[0019] Preferably, the neutralizing agent is a carbonate-based alkaline solution, wherein the carbonate-based alkaline solution is sodium carbonate and water in a mass ratio of 1:60-160.

[0020] Preferably, the distance between the water level submerging the inlet distributor and the inlet distributor during water washing of the suction section is less than 100mm.

[0021] As a preferred option, the adsorption unit should be vacuumed 3 to 5 times before it can be reused after being washed with water.

[0022] The present invention also provides an operating method for the above-mentioned long operating cycle PSA device. The method first pre-treats the feed gas through the feed buffer section to remove most of the water and liquid heavy hydrocarbons in the feed gas. The pre-treated gas is then fed into the adsorption tower for pressure swing adsorption separation of light hydrocarbons to obtain hydrogen products.

[0023] In this invention, during the regeneration and desorption of the adsorbent in the adsorption section, some of the crystalline salt adsorbed at the bottom of the adsorbent is adsorbed into the vacuum pump and enters the desorption gas buffer tank, forming an acidic environment. This causes the pipelines and devices in this section to be corroded by the acidic environment after long-term use, resulting in equipment damage. Therefore, to solve this problem, this invention adds a neutralizing agent section to the vacuum pump section. The pH of the vacuum pump environment is detected by the neutralizing agent, and a neutralizing agent is injected to ensure that the pH of the vacuum pump section is maintained in a neutral environment, ensuring that the pipelines in this section are not corroded by the acidic environment.

[0024] To ensure continuous production, this invention uses the pressure drop in the adsorption section to assess its effectiveness. When the pressure drop increases to 60-90 kPa, it indicates that the amount of crystalline salt adsorbed on the adsorbent or components has reached a threshold, affecting the operation of the entire device. In this case, the adsorption section is isolated, and the crystalline salt adsorbed in it is washed and soaked in water to remove it. After washing, it is purged with nitrogen and dried by the flare system before being reused. This method ensures that the adsorption sections with poor adsorption performance are cleaned without affecting other adsorption sections. This approach guarantees long-term operation of the device and prevents pipeline corrosion.

[0025] Compared with the prior art, this application has the following technical effects: (1) Gas-liquid separation followed by pretreatment in the feed buffer section can improve the adsorption effect and service life of the pretreated activated carbon layer. (2) Gas-liquid separation is carried out radially in the feed buffer section, which utilizes gravity and the tangential force of the airflow downward, which helps to improve the gas-liquid separation effect. At the same time, a means is reserved to carry micro-molecule water in the air intake to reduce the blockage of inorganic salts in the adsorption layer. (3) In the feed buffer section, the raw gas passes radially through the liquid separation adsorption element. The radial cross-sectional area of ​​the adsorption element in the liquid separation adsorption element is more than 4 times that of the cross-sectional area of ​​the traditional axial adsorbent. This can reduce the airflow rate and increase the adsorption efficiency. Under the same adsorption layer thickness, the total amount of ammonium salt that can be adsorbed is more than 3 times that of conventional technology. (4) In the feed buffer section, the amount of adsorbent in the adsorbent element is several times that of the traditional axial adsorbent. This can ensure the initial treatment effect while expanding the capacity of the adsorbent and extending the service life of the activated carbon layer. (5) By setting up a water washing section in the adsorption section, the production continuity can be ensured while the crystallized salt in the adsorption section is treated, thereby improving production efficiency. (6) By setting a neutralizing agent section on the vacuum section, the corrosion rate of the vacuum section pipeline and equipment can be significantly reduced, thereby improving the safety of the device operation. (7) In high-load, high-flow hydrogen processing systems, the device fundamentally solves the problem of device shutdown caused by ammonium salt crystallization through online processing, especially for devices that have been running for more than two cycles, the effect is particularly significant. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention.

[0027] Figure 2 This is a cross-sectional view of the feed buffer section of the present invention.

[0028] Figure 3This is a cross-sectional view of the adsorption section of the present invention.

[0029] In the figure, there are: feed buffer section 1, tank 101, liquid separation adsorption component 102, adsorption component 121, liquid separation component 122, support plate 1221, blade separator 1222, baffle plate 103, adsorption section 2, adsorption tank 201, adsorption layer 202, auxiliary water washing magnetic ball layer 203, product gas buffer section 3, desorption gas buffer section 4, vacuum section 5, water washing section 6, and neutralization injection section 7. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments.

[0031] Example 1: like Figure 1 As shown, a long-cycle PSA unit includes a feed buffer section 1 connected to a raw material gas feed pipe, an adsorption section 2 connected to the feed buffer section, a product gas buffer section 3 connected to the adsorption section, and a desorption gas buffer section 4 connected to the adsorption section. The adsorption section is connected to the desorption gas buffer section through a vacuum section 5. The adsorption section is also connected to a water washing section 6. The vacuum section is also connected to a neutralizing agent injection section 7. The vacuum section is a water ring vacuum pump. The feed buffer section is connected to multiple adsorption sections through several adsorption tower feed distribution plates.

[0032] The desorption gas buffer section includes a desorption gas buffer tank and a compressor connected to the desorption gas buffer tank. A control drain is installed at the bottom of the desorption gas buffer tank. The washing section includes a water injection pump, a water metering tank, and a condensate drainage system. The water injection pump is connected to the water metering tank and the adsorption section. The water injection pump is a volumetric reciprocating pump (injection volume of 2-3 m³ / h). 3 / h); The neutralizing injection section includes a water injection pump, a water metering tank, a condensate drainage system, and a pH testing agent. The pH testing agent is installed in the vacuum pump to detect the pH in the vacuum pump. The water injection pump is connected to the water metering tank and the vacuum pump. The water injection pump is a volume reciprocating pump (injection rate is 0-50L / h).

[0033] like Figure 2 As shown, the feed buffer section includes a tank body 101, a liquid separation adsorption component 102 disposed inside the tank body, and a baffle plate 103 disposed inside the tank body. The liquid separation adsorption component includes an adsorption component 121 and a liquid separation component 122 sleeved on the adsorption component. The top of the tank body is provided with a raw material gas outlet, the middle of the tank body is provided with two symmetrical raw material gas inlets, and the bottom of the tank body is provided with a condensate outlet. The raw material gas inlets are connected to the raw material gas inlet pipe. The baffle plate is disposed inside the tank body at the outlet of the raw material gas inlet. The baffle plate changes the airflow direction of the raw material gas inlet and reduces the airflow impact force.

[0034] The liquid separation and adsorption device includes a liquid separation element and an adsorption element. The liquid separation element includes a cylindrical support plate 1221 and a plurality of blade separators 1222 arranged circumferentially along the inner surface of the support plate. The support plate is provided with a cover plate at the top and a porous bottom plate at the bottom. The outer surface of the support plate is provided with a collection groove. The blade separators are wedge-shaped liquid separators. The angle between the blade separators and the central axis of the liquid separation element is 105°. The thickness of the top of the liquid separation element is 200 mm, and the thickness of the bottom of the liquid separation element is 250 mm.

[0035] The adsorption component includes an outer cylinder, an inner cylinder, and an adsorbent disposed between the inner and outer cylinders. The radius of the top ring formed by the inner and outer cylinders is 250 mm, and the radius of the bottom ring formed by the inner and outer cylinders is 200 mm. The top of the inner and outer cylinders is provided with an annular cover plate formed by the interlocking of 18 small fan-shaped cover plates. The bottom is provided with a porous support plate that connects to the inner and outer cylinders. The porous support plate has a positioning groove, which is detachably connected to the inner and outer cylinders. The inner and outer cylinders are enclosed by ribs. The ribs on the outer cylinder and the inner cylinder have a spacing of 1.2 mm. The ribs between the inner and outer cylinders have a spacing of 150 mm. The outer wall of the outer cylinder has a reinforcing rib perpendicular to the ribs every 200 mm. The outer wall of the inner cylinder also has a reinforcing rib perpendicular to the ribs every 200 mm. A layer of 16-mesh stainless steel wire mesh is laid on the bottom surface, and the wire mesh is fixed to the wire with pressure strips to prevent leakage of activated carbon particles. Long strips of activated carbon, 4–6 mm in length and 2–3 mm in particle size, are placed in both the inner and outer cylinders. A wire mesh component is also provided at the bottom of the inner cylinder, fitted onto the inner cylinder. This wire mesh component is a disc-shaped high-efficiency wire mesh separator (radius 200 mm).

[0036] like Figure 3 As shown, the adsorption unit includes an adsorption tank 201 and an adsorption layer 202 disposed inside the adsorption tank. The bottom of the adsorption tank is provided with a gas phase feed port, a vacuum section connection port, and a water washing section connection port. The gas phase feed port is connected to the adsorption tower feed distribution plate and is connected to the feed buffer tank outlet. The adsorption tower feed distribution plate consists of two layers of porous support steel plates and a single layer of GFW2.0 / 0.9 / 321 wire mesh in the middle. Four φ6mm oblique drainage holes are symmetrically arranged at the edge of the distribution plate. The adsorption layer includes an activated carbon adsorption layer 221 and a mixed adsorbent layer 222 disposed on the activated carbon adsorption layer. An auxiliary water washing magnetic ball layer 203 is provided at the bottom of the activated carbon layer. An isolation net 204 is provided between the activated carbon layer and the auxiliary water washing magnetic ball layer. The auxiliary water washing magnetic ball layer contains φ19, φ13, φ6, and φ3 inert magnetic balls, each 50mm in size. The isolation net is a 16-mesh wire mesh.

[0037] Example 2: A method for operating the above-mentioned long-cycle PSA device includes the following preparation method: (1) The feed hydrogen from the reforming unit, hydrogenation unit or other units is mixed in the feed buffer section; most of the feed gas passes radially through the liquid separator and adsorption unit in sequence, and a small amount of feed gas passes axially through the porous support plate through the gas-liquid separator and adsorbent bed in sequence. Most of the heavy molecular hydrocarbons and crystalline salts in the feed gas remain in the feed buffer tank to obtain the pretreated gas after preliminary treatment; the pretreated gas is introduced into the adsorption section, and the hydrogen is purified by pressure swing adsorption to obtain the product gas, which is then transferred to the product gas buffer tank for later use. (2) The non-hydrogen gas remaining in the adsorption tower is regenerated by vacuuming. During the adsorption regeneration process, most impurities enter the vacuum pump with the desorption gas. During the adsorption regeneration process, hydrocarbon molecules, crystal salts, acids and other substances adsorbed on the adsorbent enter the vacuum pump system with the desorption gas, forming an acidic environment in the water ring of the vacuum pump, which corrodes the vacuum pump equipment and pipelines. The pH of the vacuum pump water environment is adjusted to the range of 6.0 to 7.5 by pumping in a neutralizing agent through the neutralizing agent injection section. The neutralizing agent is a carbonate alkaline solution, which is a 1:60 ratio of sodium carbonate and water. The sodium carbonate is industrial sodium carbonate with a purity of 99.7%. (3) As the processing load of the equipment increases and the operating time increases, the adsorption tower will experience an increase in pressure drop due to the accumulation of crystalline salts and heavy hydrocarbons in the bottom distributor and bottom adsorbent bed. This weakens the adsorption effect and may even cause the pressure in the feed buffer tank to exceed the safe pressure. In such cases, the adsorption tower with the high pressure difference should be removed, and the crystalline brine at the bottom of the adsorption tower should be washed away using the water injection section. If the differential pressure in the adsorption section exceeds 60 kPa, the adsorption tower with the high pressure difference should be removed from the adsorption section for vacuuming and nitrogen purging. After successful purging, an isolation blind flange should be added to the inlet flange of the adsorption tower. Before the adsorption tower is connected to the washing section, water is injected into the inlet distributor at a volume not exceeding 100mm in height, based on the volume from the blind plate to the inlet distributor. After 20 minutes, the washing water is discharged into the sewage system. The water injection can be used for testing the washing water (chlorine or ammonium concentration). This process is repeated several times. After the washing is completed, the isolation blind plate is removed, nitrogen is introduced into the top to purge water vapor and replace air, hydrogen is pressurized, and the bottom is depressurized to the flare system. Finally, a small amount of hydrogen is introduced into the top, and the bottom is evacuated to remove all residual water vapor from the washing process. The washed adsorption tower is then put back into the adsorption section.

[0038] Example 3: A method for operating the above-mentioned long-cycle PSA device includes the following preparation method: (1) The feed hydrogen from the reforming unit, hydrogenation unit or other units is mixed in the feed buffer section; most of the feed gas passes radially through the liquid separator and adsorption unit in sequence, and a small amount of feed gas passes axially through the porous support plate through the gas-liquid separator and adsorbent bed in sequence. Most of the heavy molecular hydrocarbons and crystalline salts in the feed gas remain in the feed buffer tank to obtain the pretreated gas after preliminary treatment; the pretreated gas is introduced into the adsorption section, and the hydrogen is purified by pressure swing adsorption to obtain the product gas, which is then transferred to the product gas buffer tank for later use. (2) Non-hydrogen gas remaining in the adsorption tower is regenerated by vacuuming. During the adsorption regeneration process, most impurities enter the vacuum pump with the desorption gas. During the adsorption regeneration process, hydrocarbon molecules, crystalline salts, acids, etc. adsorbed on the adsorbent enter the vacuum pump system with the desorption gas, forming an acidic environment in the water ring of the vacuum pump, which corrodes the vacuum pump equipment and pipelines. The pH of the vacuum pump water environment is adjusted to the range of 6.0 to 7.5 by pumping in a neutralizing agent through the neutralizing agent injection section. The neutralizing agent is a carbonate alkaline solution, which is a 1:160 ratio of sodium carbonate and water. The sodium carbonate is industrial sodium carbonate with a purity of 99.7%. (3) As the processing load of the equipment increases and the operating time increases, the adsorption tower will experience an increase in pressure drop due to the accumulation of crystalline salts and heavy hydrocarbons in the bottom distributor and bottom adsorbent bed. This weakens the adsorption effect and may even cause the pressure in the feed buffer tank to exceed the safe pressure. In such cases, the adsorption tower with the high pressure difference should be removed, and the crystalline brine at the bottom of the adsorption tower should be washed away using the water injection section. If the differential pressure in the adsorption section exceeds 60 kPa, the adsorption tower with the high pressure difference should be removed from the adsorption section for vacuuming and nitrogen purging. After successful purging, an isolation blind flange should be added to the inlet flange of the adsorption tower. Before the adsorption tower is connected to the washing section, water is injected into the inlet distributor at a volume not exceeding 100mm in height, based on the volume from the blind plate to the inlet distributor. The water is left to stand for 10 minutes, and then the washing water is discharged into the sewage system. The water injection can be used for testing the washing water (chlorine or ammonium concentration). This process is repeated several times. After the washing is completed, the isolation blind plate is removed, nitrogen is introduced into the top to purge water vapor and replace the air, hydrogen is pressurized, and the bottom is depressurized to the flare system. Finally, a small amount of hydrogen is introduced into the top, and the bottom is evacuated to remove all residual water vapor from the washing process. The washed adsorption tower is then put back into the adsorption section.

[0039] Example 4: A method for operating the above-mentioned long-cycle PSA device includes the following preparation method: (1) The feed hydrogen from the reforming unit, hydrogenation unit or other units is mixed in the feed buffer section; most of the feed gas passes radially through the liquid separator and adsorption unit in sequence, and a small amount of feed gas passes axially through the porous support plate through the gas-liquid separator and adsorbent bed in sequence. Most of the heavy molecular hydrocarbons and crystalline salts in the feed gas remain in the feed buffer tank to obtain the pretreated gas after preliminary treatment; the pretreated gas is introduced into the adsorption section, and the hydrogen is purified by pressure swing adsorption to obtain the product gas, which is then transferred to the product gas buffer tank for later use. (2) The non-hydrogen gas remaining in the adsorption tower is regenerated by vacuuming. During the adsorption regeneration process, most impurities enter the vacuum pump with the desorption gas. During the adsorption regeneration process, hydrocarbon molecules, crystal salts, acids and other substances adsorbed on the adsorbent enter the vacuum pump system with the desorption gas, forming an acidic environment in the water ring of the vacuum pump, which corrodes the vacuum pump equipment and pipelines. The pH of the vacuum pump water environment is adjusted to the range of 6.0 to 7.5 by pumping in a neutralizing agent through the neutralizing agent injection section. The neutralizing agent is a carbonate alkaline solution, which is a 1:60 ratio of sodium carbonate and water. The sodium carbonate is industrial sodium carbonate with a purity of 99.7%. (3) As the processing load of the equipment increases and the operating time increases, the adsorption tower will experience an increase in pressure drop due to the accumulation of crystalline salts and heavy hydrocarbons in the bottom distributor and bottom adsorbent bed. This will weaken the adsorption effect and may even cause the pressure in the feed buffer tank to exceed the safe pressure. In such cases, the adsorption tower with the high pressure difference should be removed, and the crystalline brine at the bottom of the adsorption tower should be washed away using the water injection section. If the differential pressure in the adsorption section exceeds 60 kPa, the adsorption tower with the high pressure difference should be removed from the adsorption section for vacuuming and nitrogen purging. After successful purging, an isolation blind flange should be added to the inlet flange of the adsorption tower. Before attaching the adsorption tower, connect the water washing section. Based on the volume from the blind plate to the inlet distributor, inject water with a volume not exceeding 100mm in height of the inlet distributor. Let it stand for 30 minutes, then discharge the washing water into the wastewater system. The water injection can be used for testing the washing water (chlorine or ammonium concentration). Repeat this process several times. After the water washing is completed, remove the isolation blind plate, introduce nitrogen gas into the top to purge water vapor and replace air, pressurize with hydrogen gas, depressurize the bottom to the flare system, and finally introduce a small amount of hydrogen gas into the top and evacuate the bottom to completely remove any remaining water vapor from the water washing. Then, put the water-washed adsorption tower back into the adsorption section.

[0040] Example 5: A method for operating the above-mentioned long-cycle PSA device includes the following preparation method: (1) The feed hydrogen from the reforming unit, hydrogenation unit or other units is mixed in the feed buffer section; most of the feed gas passes radially through the liquid separator and adsorption unit in sequence, and a small amount of feed gas passes axially through the porous support plate through the gas-liquid separator and adsorbent bed in sequence. Most of the heavy molecular hydrocarbons and crystalline salts in the feed gas remain in the feed buffer tank to obtain the pretreated gas after preliminary treatment; the pretreated gas is introduced into the adsorption section, and the hydrogen is purified by pressure swing adsorption to obtain the product gas, which is then transferred to the product gas buffer tank for later use. (2) The non-hydrogen gas remaining in the adsorption tower is regenerated by vacuuming. During the adsorption regeneration process, most impurities enter the vacuum pump with the desorption gas. During the adsorption regeneration process, hydrocarbon molecules, crystal salts, acids and other substances adsorbed on the adsorbent enter the vacuum pump system with the desorption gas, forming an acidic environment in the water ring of the vacuum pump, which corrodes the vacuum pump equipment and pipelines. The pH of the vacuum pump water environment is adjusted to the range of 6.0 to 7.5 by pumping in a neutralizing agent through the neutralizing agent injection section. The neutralizing agent is a carbonate alkaline solution, which is a 1:60 ratio of sodium carbonate and water. The sodium carbonate is industrial sodium carbonate with a purity of 99.7%. (3) As the processing load of the equipment increases and the operating time increases, the adsorption tower will experience an increase in pressure drop due to the accumulation of crystalline salts and heavy hydrocarbons in the bottom distributor and bottom adsorbent bed. This will weaken the adsorption effect and may even cause the pressure in the feed buffer tank to exceed the safe pressure. In such cases, the adsorption tower with the high pressure difference should be removed, and the crystalline brine at the bottom of the adsorption tower should be washed away using the water injection section. If the differential pressure in the adsorption section exceeds 60 kPa, the adsorption tower with the high pressure difference should be removed from the adsorption section for vacuuming and nitrogen purging. After successful purging, an isolation blind flange should be added to the inlet flange of the adsorption tower. Before attaching the adsorption tower, connect the water washing section. Based on the volume from the blind plate to the inlet distributor, inject water with a volume not exceeding 100mm in height of the inlet distributor. Let it stand for 20 minutes, then discharge the washing water into the wastewater system. The water injection can be used for testing the washing water (chlorine or ammonium concentration). Repeat this process several times. After the water washing is completed, remove the isolation blind plate, introduce nitrogen gas into the top to purge water vapor and replace air, pressurize with hydrogen gas, depressurize the bottom to the flare system, and finally introduce a small amount of hydrogen gas into the top and evacuate the bottom to completely remove any remaining water vapor from the water washing. Then, put the washed adsorption tower back into the adsorption section.

[0041] Comparative Example 1: In Comparative Example 1, the feed buffer tank of Example 1 is set as an axially arranged defoaming layer.

[0042] Comparative Example 2: Comparative Example 2 replaced the raw material buffer tank in Example 1 with the pretreatment device disclosed in CN216440254U.

[0043] Comparative Example 3: In Comparative Example 3, the top and bottom rings of the liquid separator and adsorption element in Example 1 have the same radius, which is 225 mm.

[0044] Comparative Example 4: In Comparative Example 4, no water washing section was used for water washing, and all other conditions were the same as in Example 2.

[0045] Comparative Example 5: In Comparative Example 5, no neutralizing agent was used; all other conditions were the same as in Example 2.

[0046] Example of detection: The PSA unit was observed and statistically analyzed when the technical solutions of Examples 2 to 5 and Comparative Examples 1 to 5 were used to process the raw gas (the feed rate of the raw gas was 150,000 cubic meters per hour). The statistical items were: the initial pressure difference at the bottom of the adsorption section, the pressure difference at the bottom of the adsorption section after 100 days of treatment, the corrosion and leakage cycle of the vacuum pump pipeline (days), and the blockage cycle of the feed buffer tank (days). The statistical results are shown in Table 1.

[0047] Table 1 Statistical Results As shown in Table 1, when the feed gas is treated using the long-cycle PSA device and method provided by the present invention, the initial pressure difference at the bottom of the adsorption section increases from 25 kPa to 28-30 kPa after 100 days of treatment. Furthermore, after water washing and neutralization treatment, no corrosion occurs in the pipeline, and the feed buffer tank does not become clogged, enabling continuous long-cycle treatment of the feed gas.

[0048] In Comparative Example 1, the feed buffer tank was treated only with an axially arranged defoaming screen. The results showed that after 100 days of treatment, the initial pressure difference at the bottom of the adsorption section of Comparative Example 1 increased from 30 kPa to 80 kPa, and the feed buffer tank became completely blocked after 400 days of use.

[0049] Comparative Example 2 uses the device disclosed in CN216440254U. It was found that when Comparative Example 2 processes feed gas with high salt and liquid heavy hydrocarbon content, its pretreatment device becomes completely clogged after 90 days, making it unable to process the feed gas for a long time.

[0050] In Comparative Example 3, the liquid distribution element and the adsorption element in the buffer tank were set as nested cylinders. The results showed that the effective cross-section of the adsorption element was reduced, the capacity of the adsorbent was reduced, and the processing efficiency and processing cycle of the feed buffer section were reduced compared with Example 1.

[0051] In Comparative Example 4, no water washing treatment was performed, and the pressure difference at the bottom of the adsorption section of Comparative Example 4 increased to 80 kPa after 365 days.

[0052] In Comparative Example 5, no neutralizing agent was used, and it was found that corrosion and leakage occurred in the vacuum pump pipeline of Comparative Example 5 180 days after treatment.

[0053] In summary, the long-cycle PSA device and method provided by the present invention can process feed gas with high salt content and high liquid heavy hydrocarbon content. The processing can be continuous and the operating cycle is long. At the same time, the pipelines of the device will not be corroded, and the safety of the device is significantly improved.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A long-cycle PSA device, characterized in that, It includes a feed buffer section (1) connected to the raw material gas, an adsorption section (2) connected to the feed buffer section, a product gas buffer section (3) connected to the adsorption section, and a desorption gas buffer section (4). The feed buffer section includes a tank (101), a liquid separation adsorption component (102) disposed in the tank, and a baffle plate (103) for changing the gas flow direction at the feed inlet. The liquid separation adsorption component includes an adsorption component (121) and a liquid separation component (122) sleeved on the adsorption component.

2. The long-cycle PSA device according to claim 1, characterized in that, The adsorption element is a hollow frustum with a thickness that gradually decreases from top to bottom, and the liquid distribution element is a hollow frustum with a thickness that gradually increases from top to bottom. The thickness of the adsorption element is 200~250 mm, and the thickness of the liquid distribution element is 200~250 mm.

3. The long-cycle PSA device according to claim 1 or 2, characterized in that, The hollow part of the adsorption element is also provided with a wire mesh (123), the adsorption element is sleeved on the wire mesh, the liquid separation element includes a support plate (1221), a blade separator (1222) provided on the support plate, and a collection groove provided on the support plate grid. The angle between the blade separator and the central axis of the adsorption element is 105~135°, and the blade is a wedge-shaped liquid separator.

4. The long-cycle PSA device according to claim 1, characterized in that, The adsorption unit includes an adsorption tank (201) and an adsorption layer (202) disposed in the adsorption tank. The adsorption layer includes an activated carbon adsorption layer (221) and a mixed adsorbent layer (222) disposed on the activated carbon adsorption layer. An auxiliary water-washing magnetic ball layer (203) is provided at the bottom of the activated carbon layer, and an isolation net (204) is provided between the activated carbon layer and the auxiliary water-washing magnetic ball layer.

5. The long-cycle PSA device according to claim 4, characterized in that, The adsorption section is also connected to the vacuum section (5) and the water washing section (6). The vacuum section is connected to the analysis section. The vacuum section is a water ring vacuum pump. The water washing section includes a water metering tank, a water pump and a condensate drainage system.

6. The long-cycle PSA device according to claim 5, characterized in that, The vacuum unit is also connected to the neutralization injection unit (7), which includes a water metering tank, a water injection pump, a condensate drainage system, and a pH detection device.

7. A method for operating a long-cycle PSA device according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) The raw material gas is fed into the feed buffer section for pretreatment to obtain pretreated gas, and then the pretreated gas is fed into the adsorption tower for pressure swing adsorption to produce product gas for later use. (2) The desorption gas is drawn into the desorption gas buffer tank using the vacuum pumping unit. The neutralizing agent unit connected to the vacuum pumping unit detects the pH of the solution in the vacuum pump and injects neutralizing agent to maintain the pH of the vacuum pumping unit at 6~7.

5. (3) After replacing the adsorption section with nitrogen, the adsorption section is washed with water. After washing, the cleaning water is removed and the remaining moisture is purged with nitrogen. First replace with nitrogen, then purge with hydrogen. Gas is injected at the top and a flare system is set at the bottom.

8. The method according to claim 7, characterized in that, The neutralizing agent is a carbonate-based alkaline solution.

9. The method according to claim 7, characterized in that, During water washing of the suction section, the water level submerging the inlet distributor is less than 100 mm away from the inlet distributor.

10. The method according to claim 7, characterized in that, Before reusing the adsorption unit after washing, it needs to be vacuumed 3-5 times.

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