Treatment equipment and treatment method of hydrogen chloride fluid

Abstract

The invention relates to treatment equipment and a treatment method for hydrogen chloride fluid, the treatment equipment comprises a Nessler pump, and a cooling tank, a water segregator and a circulating pump which are connected with a working liquid outlet of the Nessler pump, and a gas outlet of the Nessler pump is connected with a gas-liquid separator and a gas storage tank; the hydrogen chloride fluid comprises hydrogen chloride gas, hydrogen chloride mixed gas containing organic or inorganic substances and other mixed gas containing hydrogen chloride, and a liquid ring vacuum pump is utilized, and appropriate liquid is arranged in the pump to pressurize low-pressure gas. Compared with existing equipment and methods, the method is high in pressurization efficiency, does not need to frequently replace the working fluid, does not pollute gas in the pump, can also remove water for the fluid part, and does not generate pollutants in the operation process of the equipment.

Description

Technical Field

[0001] This invention belongs to the field of gas treatment and environmental protection technology, and relates to a treatment device and method for a mixed gas containing organic or inorganic substances of hydrogen chloride, particularly a treatment device and method for hydrogen chloride fluid. Background Technology

[0002] Chlorine (Cl2) is an important basic chemical raw material and the source of hydrogen chloride (HCl) gas. In the preparation of chemicals using Cl2, processes often require operation under low pressure (<0.1 MPa or 1 atmosphere), resulting in HCl gas pressures below atmospheric pressure. This causes inconvenience for subsequent gas pipeline transportation and use. For example, in the propylene chlorination process for producing allyl chloride, for safety reasons and to increase the reaction rate and suppress or reduce the formation of byproducts, the reaction pressure needs to be controlled below 0.08 MPa. As the products cool and separate, the pressure of the unreacted propylene feedstock and HCl mixture drops to 0.02-0.06 MPa. Similar situations are common in fluorochemical processes. For instance, HCl gas containing impurities such as hydrogen fluoride, R22, and R23, although water washing can significantly reduce the impurity content, still produces HCl with a pressure of only 0.01-0.06 MPa after low-pressure hydrochloric acid removal. To achieve HCl treatment and utilization, the low-pressure HCl needs to be compressed to medium or high pressure for easy pipeline transportation or storage. However, HCl is hygroscopic and highly corrosive. Some processes involve flammable and explosive gases like propylene, some contain low-boiling-point oils, and some contain strong acidic gases like inorganic hydrogen fluoride. This leads to sealing difficulties in gas compression equipment (such as piston compressors, diaphragm compressors, screw compressors, and centrifugal compressors), resulting in excessively low air-pressure ratios, frequent maintenance, and an inability to meet long-term pressurization requirements. To meet the needs of different industries, there is an urgent need to develop a universal, highly sealing, safe, reliable, and easy-to-install and maintain gas pressurization method. Nash pumps exhibit unique advantages in handling corrosive, toxic, flammable, and explosive gases, especially in the compression and transportation of dry gases such as chlorine, propylene, and hydrogen, making them an ideal choice. Nash pumps often use concentrated sulfuric acid as the liquid medium for gas pressurization and transportation. During operation, a sulfuric acid liquid ring seal forces the gas from the low-pressure end to the high-pressure end, while the concentrated sulfuric acid is discharged from the high-pressure end along with the gas. After separation and cooling by a separator, it is recycled.

[0003] However, Nash pumps for compressing HCl gas have the following drawbacks: 1. The strong corrosiveness of HCl causes severe corrosion of the equipment, resulting in a significant decrease in gas delivery and compression capacity, requiring frequent impeller maintenance and replacement; 2. When using concentrated sulfuric acid as the liquid medium, it is suitable for handling dry gases, but its efficiency is low when handling gases containing water, requiring frequent replacement of the working fluid; 3. HCl containing hydrocarbon organic compounds easily reacts with sulfuric acid, contaminating and consuming the liquid medium, rapidly increasing operating costs, and the reaction products also cause pollution. These problems make it difficult for enterprises to guarantee continuous and stable operation, highlighting cost and safety issues. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a device and method for processing hydrogen chloride fluid. Specifically, it relates to a method for pressurizing hydrogen chloride gas or hydrogen chloride mixtures containing inorganic or organic matter, and other hydrogen chloride-containing gases. The method utilizes a liquid ring vacuum pump, with a suitable liquid inside the pump to pressurize the negative pressure gas. This invention modifies the existing Nessler pump, making it applicable to the pressurization of hydrogen chloride or hydrogen chloride mixtures containing impurities, thus solving the drawback of conventional compression equipment being unable to meet the pressurization requirements of low-pressure HCl gas.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] The present invention provides a hydrogen chloride fluid treatment device, including a Nessler pump. The impeller of the Nessler pump is made of carbon steel and coated with polytetrafluoroethylene. Its function is to avoid the strong corrosiveness of HCl to the impeller and extend the service life of the device.

[0007] Furthermore, the Nash pump uses a high-boiling-point, acid-resistant, hydrophobic liquid organic material as the working fluid.

[0008] Furthermore, the liquid organic material is selected from those containing C. 8-20 Saturated alkanes containing 0-3 carbon atoms 1-4 The liquid mixture of one or more of the following: benzene with saturated alkane substituents, chlorobenzene containing 1-3 Cl substituents, or liquid chlorinated paraffin.

[0009] Furthermore, the one containing C 8-20 The saturated alkane is selected from octane, undecane, or eicosane, etc. In this embodiment of the invention, eicosane is used as the working fluid.

[0010] Furthermore, the one containing 0-3 C 1-4 The saturated alkane substituent in the benzene is selected from benzene, ethylbenzene, propenzene, xylene, diethylbenzene, trimethylbenzene, triethylbenzene, etc. In one embodiment of the present invention, pseudotrimethylbenzene is used as the working liquid.

[0011] Furthermore, the chlorobenzene containing 1-3 Cl substituents is selected from monochlorobenzene, dichlorobenzene, trichlorobenzene, etc. In one embodiment of the present invention, 1,2,4-trichlorobenzene is used as the working liquid.

[0012] Furthermore, the liquid chlorinated paraffin has the chemical formula C0. n H 2n+2-x Cl x , where n = 8 - 20, x = 1 - 3.

[0013] In embodiments of the present invention, the processing equipment further includes a cooling tank, a water distributor, and a circulating pump connected in series with the Nash pump via pipelines, and the outlet of the Nash pump is also connected in sequence to a gas-liquid separator via pipelines.

[0014] After the working liquid and HCl are discharged from the outlet of the Nessler pump, the HCl enters the gas-liquid separator. The separated HCl gas enters the gas storage tank for downstream use or is directly used in downstream processes via pipeline. The working liquid separated from the cooling tank enters the water separator and then enters the circulating pump, where it enters the Nessler pump together with the HCl to be processed later.

[0015] This invention also provides a method for processing hydrogen chloride fluid. The hydrogen chloride fluid enters a Nessler pump and is compressed to obtain compressed gas. After passing through a gas-liquid separator, it enters a gas storage tank. The working liquid in the Nessler pump enters a cooling tank for cooling and then enters a water separator. The working liquid after being processed by the water separator (if water is present) is then injected into the Nessler pump for recycling. The working liquid in the Nessler pump is a non-sulfuric acid organic liquid.

[0016] Preferably, the hydrogen chloride fluid is a hydrogen chloride mixture containing organic or inorganic substances; the organic substances are dimethyl carbonate, C... 1-4 Saturated alkanes, C 2-5 Alkenes or alkynes, C 1-3 Halogenated saturated alkanes, alkenes, or alkynes, wherein C 1-3 Halogenated saturated alkanes or alkenes include C 1-3 Fluorinated saturated alkanes or alkenes, C 1-5 Chlorinated saturated alkanes, alkenes, or alkynes, as well as chlorofluorocarbons containing both fluorine and chlorine, and inorganic impurities including PF5, HF, H2S, SOx, and NOx; in SOx, x = 2-3, and in NOx, x = 1-2.

[0017] In addition, the hydrogen chloride fluid also includes hydrogen chloride gas. The processing equipment and method provided by this invention enable the pressurized delivery of hydrogen chloride gas.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] (1) This invention develops an improved Nash pump pressurization process that involves coating the impeller surface with polytetrafluoroethylene (PTFE) and using a high-boiling-point, acid-resistant organic compound as the liquid medium. This process enables the compression and pressurization of low-pressure HCl gas (including HCl gas and impure HCl gas, i.e., mixed gases containing alkanes, alkenes, alkynes, hydrogen fluoride, H2S, SOx (x=2-3), NOx (x=1-2), organic fluorine gases, organic chlorine gases, etc.) to 0.3-10.0 MPa. Compared to existing gas compression and pressurization methods, this invention exhibits superior corrosion resistance, making it particularly suitable for compressing and pressurizing various HCl mixtures. The equipment operates stably, the gas pressure remains stable after pressurization with minimal fluctuations, and there are no safety hazards. This effectively meets the requirements of downstream equipment.

[0020] (2) The processing equipment provided by the present invention uses an impeller with a surface coating of polytetrafluoroethylene, which can withstand the corrosion of conventional inorganic acidic gases or liquids. It has excellent anti-corrosion ability against HCl, hydrochloric acid, sulfuric acid, H2S, SOx, NOx, phosphoric acid, nitric acid, etc. The impeller is easy to maintain and has a long service life.

[0021] (3) The processing equipment provided by the present invention uses high-boiling-point, acid-resistant, hydrophobic liquid organic matter instead of concentrated sulfuric acid as the working medium, which avoids the pollution problem caused by the reaction of organic impurities (such as propylene) in HCl with sulfuric acid. There is no need to replace the working fluid, which completely solves the problem of sulfuric acid waste treatment and greatly reduces the cost of use.

[0022] (4) The present invention uses a high-boiling-point, acid-resistant, hydrophobic liquid organic substance as the working medium. It does not react with the gas and has excellent compression and pressurization capabilities for dry or water-containing HCl gas. Compared with sulfuric acid working solution, which is only suitable for dry gas, the scope of application of the present invention is greatly expanded. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a schematic diagram of a hydrogen chloride fluid treatment device provided in Embodiment 1 of the present invention; wherein, 1-Nessler pump, 2-cooling tank, 3-water separator, 4-circulating pump, 5-gas-liquid separator, 6-storage tank.

[0025] Figure 2 This is a structural diagram of an existing Nessler pump. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] Existing Nash pump structures such as Figure 2 As shown, inside a circular pump body A, there is an eccentrically mounted rotor impeller B relative to the central axis of the pump body. The rotating impeller, through its centrifugal force, causes the working fluid to flow through channel D to the periphery of the pump cavity, thus forming a liquid ring C. When the liquid ring vacuum pump is operating, the gas mixture drawn into the pump enters the impeller through the suction port H on the intermediate partition E, thereby creating a vacuum at the pump inlet. The gas mixture is located in the impeller cavity between the inner wall of the liquid ring and the root of the blades. As the impeller rotor rotates, the length of the blades entering the liquid ring increases, reducing the volume between the liquid ring and the blade root. The volume of the gas mixture is compressed until it is discharged through the discharge port J (outlet) in the intermediate partition K.

[0029] This invention modifies the existing Nash pump structure by using carbon steel for the impeller and coating it with polytetrafluoroethylene (PTFE). This coating helps to prevent the strong corrosive effect of HCl on the impeller and extends the service life of the equipment. The Nash pump uses a high-boiling-point, acid-resistant, hydrophobic liquid organic material, selected from those containing C... 8-20 Saturated alkanes, such as octane, undecane, and eicosane, contain 0-3 carbon atoms. 1-4 Benzene with saturated alkane substituents, such as benzene, ethylbenzene, propylbenzene, xylene, methylethylbenzene, trimethylbenzene, etc.; chlorobenzenes containing 1-3 Cl substituents, such as monochlorobenzene, dichlorobenzene, trichlorobenzene, etc.; liquid chlorinated paraffin C. n H 2n+2-x Cl x( Where n = 8-20, x = 1-3) or a liquid mixture of one or more of the above organic compounds.

[0030] Example 1: Structure of a hydrogen chloride fluid processing device

[0031] like Figure 1As shown, the system includes a modified Nash pump 1, a cooling tank 2, a water distributor 3, a circulating pump 4, a gas-liquid separator 5, and a storage tank 6. The Nash pump 1 is connected in series with the cooling tank 2, the water distributor 3, and the circulating pump 4 via pipelines. The outlet of the Nash pump 1 is also connected to the gas-liquid separator 5 and the gas storage tank 6 via pipelines.

[0032] Cooling tank 2 cools the working liquid at the outlet, ensuring that the working liquid temperature is close to room temperature during use, thereby achieving the cooling and liquefaction of gaseous water and preventing the working liquid from evaporating and being lost, and thus separating and removing liquid water in water separator 3.

[0033] The gas-liquid separator 5 includes a separator body and a demister and cooling coil installed within the separator body. The demister can separate and collect liquid droplets in the gas, and the cooling coil can be cooled by introducing a low-temperature fluid. The separator body has a fluid inlet pipe and a fluid outlet pipe connected internally, and gas-liquid separation is achieved through cooling. The fluid inlet pipe of the gas-liquid separator 5 is connected to the outlet of the Nash pump 1, and the fluid outlet pipe of the gas-liquid separator 5 is connected to the gas storage tank 6. Since the working liquids are all high-boiling-point substances, the gas-liquid separator 5 separates the small amount of working liquid entrained in the HCl from the HCl gas.

[0034] Gas-liquid separators with coolers are commonly used devices in this field. Those skilled in the art can select similar devices as needed and can refer to the structure disclosed in the published patent "Gas-liquid separator, air conditioning system and operation control method" (Publication No.: CN117906320A).

[0035] The water separator 3 and the gas-liquid separator 5 have similar structures. The working fluid is cooled by a cooling method. Since the working fluid and water are immiscible, the water is separated after the organic phase and the water phase are separated in the water separator.

[0036] After the working liquid and HCl are discharged from the outlet of the Nessler pump, the gas part enters the gas-liquid separator. The separated HCl gas enters the gas storage tank for downstream use. The liquid separated by the gas-liquid separator enters the water separator for liquid collection and water removal, and then enters the circulating pump. Together with the HCl to be processed, it enters the inlet of the Nessler pump. The working liquid at the outlet directly enters the cooling tank 2, and is injected into the Nessler pump for circulation through the water separator 3 and the circulating pump 6.

[0037] The following section describes this technology in conjunction with a specific working process:

[0038] Example 2:

[0039] The propylene chloride process produces a mixture of propylene and HCl (propylene:HCl = 85:15) at a pressure of 0.03 MPa, room temperature, and a water content of 50 ppm. This gas enters a Nash pump with a carbon steel impeller coated with PTFE and eicosane as the working fluid. The unit has a processing capacity of 10 cubic meters per hour. After compression, the gas pressure is increased to 0.5 MPa. The compressed gas then passes through a gas-liquid separator and enters a gas storage tank for downstream use, with a water content of 51 ppm. The eicosane is cooled in a cooling tank, enters a water separator, and is then circulated back into the Nash pump for reuse. The low-pressure HCl mixture is compressed from 0.03 MPa to 0.5 MPa with almost no change in water content. Furthermore, eicosane does not react with propylene. The entire system has good sealing and high safety. The unit has been running continuously for 6 months without impeller corrosion or replacement of the working medium.

[0040] Example 3:

[0041] The R22 (difluorochloromethane) process produces a mixture of R22 and HCl (R22:HCl = 2:98), with a pressure of 0.02 MPa, room temperature, and a water content of 300 ppm. This gas enters a Nash pump with a carbon steel impeller coated with polytetrafluoroethylene and using pseudotrimethylbenzene as the working fluid. The unit has a processing capacity of 20 cubic meters per hour. After compression, the gas pressure is increased to 0.6 MPa. The compressed gas passes through a gas-liquid separator and then enters a gas storage tank for downstream users, with a water content of 305 ppm. The pseudotrimethylbenzene is cooled in a cooling tank, enters a water separator, and then is circulated back into the Nash pump for reuse. The low-pressure HCl mixture, after compression, increases in pressure from 0.03 MPa to 0.6 MPa with almost no change in water content. Pseudotrimethylbenzene does not react with R22 or HCl, demonstrating the good sealing and high safety of the entire system. After 10 months of continuous operation, the impeller showed no corrosion, and the working medium was not changed.

[0042] Example 4:

[0043] A mixture of HF and HCl (HF: 1000 ppm), at a pressure of 0.02 MPa and room temperature, with a water content of 1500 ppm, is introduced into a Nessler pump with a carbon steel impeller coated with polytetrafluoroethylene. The pump uses 1,2,4-trichlorobenzene as the working fluid. The unit has a processing capacity of 10 cubic meters per hour. After two-stage compression, the gas pressure is increased to 6.0 MPa. The compressed gas then passes through a gas-liquid separator and enters a gas storage tank for downstream use. The gas contains 800 ppm of water. The 1,2,4-trichlorobenzene is cooled in a cooling tank and enters a water separator. Water appears in the upper layer, while the lower layer contains 1,2,4-trichlorobenzene. The lower layer of organic working fluid is circulated back into the Nessler pump for reuse. The upper layer of water is discharged for treatment periodically. The low-pressure HCl mixture was compressed from 0.02 MPa to 6.0 MPa. This compression process liquefied and separated some of the moisture. Furthermore, 1,2,4-trichlorobenzene showed no reaction with HF or HCl, demonstrating the excellent sealing and high safety of the entire system. After 12 months of continuous operation, the impeller showed no corrosion, and the working medium remained unchanged.

[0044] As a further modification, a multi-stage series connection of Nash pumps can be used to increase the pressure of the compressed gas to 10 MPa.

[0045] Compared to existing equipment and methods, this method is more efficient (high pressurization efficiency), stable (no pollution to pressurized gas, and can also partially remove water from the gas), environmentally friendly (no pollutants are generated during equipment operation), and environmentally friendly (the working liquid inside the pump has stable properties and can be recycled for a long time).

[0046] Example 5:

[0047] Hydrogen chloride gas, pressure 0.04 MPa, temperature room temperature, water content 1000 ppm. This gas enters a carbon steel impeller coated with polytetrafluoroethylene (PTFE) and is treated with chlorinated paraffin C8H. 17 The Nash pump, using Cl as the working fluid, pressurizes the gas to 3.0 MPa after two-stage compression. The compressed gas then passes through a gas-liquid separator and is transported to a gas storage tank for downstream use. The gas contains 700 ppm of water. Chlorinated paraffin (C8H) 17 After being cooled in the cooling tank, Cl enters the water distributor where some water flows out for processing. The bottom working fluid is then injected into the Nash pump for recycling via a circulating pump.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for processing hydrogen chloride fluid, characterized in that, This includes a Nash pump, in which the working fluid is a high-boiling-point, acid-resistant, hydrophobic liquid organic compound.

2. The hydrogen chloride fluid processing equipment according to claim 1, characterized in that, The impeller in the Nash pump is made of carbon steel and coated with polytetrafluoroethylene.

3. The hydrogen chloride fluid processing equipment according to claim 1, characterized in that, The liquid organic matter is selected from those containing C. 8-20 Saturated alkanes containing 0-3 carbon atoms 1-4 A liquid mixture of one or more of the following: benzene with saturated alkane substituents, chlorobenzene containing 1-3 Cl substituents, or liquid chlorinated paraffin.

4. The hydrogen chloride fluid processing equipment according to claim 3, characterized in that, The one containing C 8-20 The saturated alkanes are selected from octane, undecane, or eicosane.

5. The hydrogen chloride fluid processing equipment according to claim 3, characterized in that, The one containing 0-3 C 1-4 The saturated alkane substituents of benzene are selected from benzene, toluene, ethylbenzene, propenzene, xylene, methyl ethylbenzene, and trimethylbenzene.

6. The hydrogen chloride fluid processing equipment according to claim 3, characterized in that, The chlorobenzene containing 1-3 Cl substituents is selected from monochlorobenzene, dichlorobenzene, and trichlorobenzene.

7. The hydrogen chloride fluid processing equipment according to claim 3, characterized in that, The liquid chlorinated paraffin has the chemical formula C. n H 2n+2-x Cl x , where n = 8 - 20, x = 1 - 3.

8. The hydrogen chloride fluid processing equipment according to claim 1, characterized in that, The processing equipment also includes a cooling tank, a water distributor, and a circulating pump connected in series with the Nash pump via pipelines. The outlet of the Nash pump is also connected in sequence to a gas-liquid separator via pipelines.

9. A method for treating hydrogen chloride fluid, characterized in that, Hydrogen chloride fluid enters the Nash pump and is compressed to obtain compressed gas. After passing through a gas-liquid separator, it becomes high-pressure gas. The working liquid in the Nash pump enters the cooling tank for cooling and then enters the water distributor. The working liquid after being treated by the water distributor is then injected into the Nash pump for recycling. The working liquid in the Nash pump is a non-sulfuric acid organic liquid.

10. The method for treating hydrogen chloride fluid according to claim 9, characterized in that, The hydrogen chloride fluid is selected from hydrogen chloride gas or a mixture of hydrogen chloride gas containing inorganic or organic compounds, the organic compounds being dimethyl carbonate, C... 1-4 Saturated alkanes, C 2-5 olefins, C 2-3 alkynes, C 1-3 Halogenated saturated alkanes, alkenes, or alkynes, wherein C 1-3 Halogenated saturated alkanes, alkenes, or alkynes include C 1-3 Fluorinated saturated alkanes, C 1-5 Chlorinated saturated alkanes, alkenes, or alkynes, as well as chlorofluorocarbons containing both fluorine and chlorine, and inorganic compounds including PF5, HF, H2S, SOx, and NOx; in SOx, x = 2-3, and in NOx, x = 1-2.

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