Refrigerant r134a dewatering device and dewatering method

Abstract

The application discloses a refrigerant R134a dehydration device and a dehydration method. By arranging two or more dehydration adsorption towers in series in an adsorption unit, the R134a raw material can be continuously subjected to multistage adsorption dehydration treatment, and the water in the R134a raw material can be efficiently removed through multistage adsorption purification, so that the R134a product with water content of less than or equal to 0.1 ppm (w%) can be finally collected. The above refrigerant R134a dehydration device is suitable for deep dehydration of R134a, and has the advantages of energy saving and consumption reduction through adsorption dehydration of adsorbents.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology and relates to the purification technology of environmentally friendly refrigerants, particularly to a refrigerant R134a dehydration device and dehydration method. Background Technology

[0002] 1,1,1,2-Tetrafluoroethane (R134a) is a third-generation refrigerant, belonging to the HFC class of substances. It does not contain chlorine atoms and is considered an environmentally friendly refrigerant. Currently, industrial-grade R134a products have a water content ≤10 ppm (w%) and are mainly used in large refrigeration units such as automotive air conditioners, central air conditioners, and refrigerators. However, precision temperature controllers have much stricter requirements for the water content in R134a, requiring a water content ≤0.1 ppm (w%).

[0003] Currently, the main methods for removing water from R134a are distillation and adsorption. However, the R134a products obtained using these methods do not meet the requirement of a water content of ≤0.1 ppm (w%). For example, the apparatus for separating and purifying R134a using distillation technology disclosed in Chinese utility model patent CN216755432U produces an R134a product with a water content of 7 ppm after dehydration, which does not meet the requirements for higher precision temperature controllers. Furthermore, the method for drying R134a products using 5A molecular sieves disclosed in Chinese invention patent CN115626864A, after comparative testing, shows that the 5A molecular sieve still does not achieve a water removal depth of ≤0.1 ppm (w%) in the R134a product.

[0004] In summary, there is an urgent need to propose a novel dehydration and purification scheme for refrigerant R134a to meet the requirements of higher precision temperature controllers regarding the water content in R134a. Summary of the Invention

[0005] The purpose of this invention is to provide a refrigerant R134a dehydration device and method, which removes water from R134a by adsorption, reducing the water content in R134a to ≤0.1ppm. This solves the problem that the existing R134a dehydration technology cannot achieve a removal depth of ≤0.1ppm, thus failing to meet the water content requirements of higher precision temperature controllers.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides a refrigerant R134a dehydration device, comprising:

[0008] An adsorption unit includes at least two dehydration adsorption towers connected in series along the raw material flow direction to perform at least two stages of adsorption and dehydration on R134a raw material.

[0009] A filtration system whose inlet is connected to the outlet of the adsorption unit;

[0010] The product collection device is connected to the outlet of the filtration system.

[0011] Preferably, the system further includes a moisture measuring device, and the outlet of any of the dehydration adsorption towers is connected to the moisture measuring device, which is used to detect the water content of the outlet product of any of the dehydration adsorption towers.

[0012] Preferably, the system further includes a purging unit, wherein the inlet of any of the dehydration adsorption towers is connected to the outlet of the purging unit.

[0013] Preferably, the system further includes a vacuum unit, and the inlet of any of the dehydration adsorption towers is connected to the vacuum unit.

[0014] Preferably, the vacuum unit includes a vacuum buffer tank, a vacuum pump, and a tail gas treatment system connected in sequence. The inlet of the vacuum buffer tank is connected to the inlet of any of the dehydration adsorption towers, and the vacuum buffer tank is also directly connected to the tail gas treatment system.

[0015] Preferably, the adsorption unit includes a first dehydration adsorption tower and a second dehydration adsorption tower connected in series along the raw material flow direction, wherein:

[0016] The adsorbents installed in the first dehydration adsorption tower include type A molecular sieve adsorbents and / or modified type A molecular sieve adsorbents;

[0017] The adsorbents provided in the second dehydration adsorption tower include metal ion-modified nano ZSM-5 molecular sieve adsorbents and / or metal ion-modified nano TS-1 molecular sieve adsorbents.

[0018] Preferably, the device further includes a raw material storage device connected to the inlet of the adsorption unit, the raw material storage device being used to store and supply R134a raw material to be dehydrated to the adsorption unit.

[0019] Preferably, it also includes a flow meter connected between the inlet of the adsorption unit and the raw material storage device.

[0020] The present invention also proposes a method for dehydrating refrigerant R134a, implemented using the above-mentioned refrigerant R134a dehydration device, comprising:

[0021] R134a raw material is fed into the adsorption unit, and the first dehydration adsorption tower and the second dehydration adsorption tower respectively perform primary adsorption dehydration and secondary adsorption dehydration on the R134a raw material.

[0022] The water content of the product at the outlet of the second dehydration adsorption tower is detected by the moisture measuring device until the water content of the product at the outlet of the second dehydration adsorption tower is ≤0.1ppm. Then, the product at the outlet of the second dehydration adsorption tower is discharged into the product collection device for collection.

[0023] Preferably, the weight hourly space velocity (WHSV) of the R134a feedstock introduced into the adsorption unit is 0.05–1.2 h⁻¹. -1 The first dehydration adsorption tower has an adsorption temperature of room temperature and an adsorption pressure of 0.1–0.5 MPa; the second dehydration adsorption tower has an adsorption temperature of room temperature and an adsorption pressure of 0.1–1.0 MPa.

[0024] The present invention achieves the following technical effects compared to the prior art:

[0025] The refrigerant R134a dehydration device and method proposed in this invention utilize two or more dehydration adsorption towers connected in series in the adsorption unit to continuously perform multi-stage adsorption dehydration treatment on R134a raw material. Through multi-stage adsorption purification, water in the R134a raw material can be efficiently removed, ultimately yielding an R134a product with a water content ≤0.1 ppm (w%). The aforementioned refrigerant R134a dehydration device is suitable for deep dehydration of R134a, employing adsorption dehydration with adsorbents, and offers advantages in energy saving and consumption reduction. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the refrigerant R134a dehydration device disclosed in the embodiments of the present invention;

[0028] Figure 2 This is a schematic diagram of the installation of the purging unit and the vacuuming unit in the refrigerant R134a dehydration device disclosed in the embodiments of the present invention.

[0029] In the figure, the attached reference numerals are:

[0030] 100. Refrigerant R134a dehydration device;

[0031] 1. Raw material storage device;

[0032] 2. Flow meter;

[0033] 3. Adsorption unit; 31. First dehydration adsorption tower; 32. Second dehydration adsorption tower;

[0034] 4. Filtration system;

[0035] 5. Moisture measuring device;

[0036] 6. Product collection device;

[0037] 7. Purging unit;

[0038] 8. Vacuum pumping unit; 81. Vacuum buffer tank; 82. Vacuum pump; 83. Exhaust gas treatment system;

[0039] K1~K11, Valves. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The purpose of this invention is to provide a refrigerant R134a dehydration device and method, which removes water from R134a by adsorption, reducing the water content in R134a to ≤0.1ppm. This solves the problem that existing R134a dehydration technologies cannot achieve a removal depth of ≤0.1ppm, thus failing to meet the water content requirements of higher precision temperature controllers.

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] like Figure 1 As shown, this embodiment provides a refrigerant R134a dehydration device 100, including an adsorption unit 3, a filtration system 4 whose inlet is connected to the outlet of the adsorption unit 3, a product collection device 6 whose inlet is connected to the outlet of the filtration system 4, and a moisture measuring device 5. The adsorption unit 3 includes at least two dehydration adsorption towers arranged in series along the raw material flow direction to perform at least two stages of adsorption dehydration on the R134a raw material. The inlet of the moisture measuring device 5 is connected to the outlet of any one of the dehydration adsorption towers, and the moisture measuring device 5 is used to detect the water content of the product at the outlet of any one of the dehydration adsorption towers. Preferably, the moisture measuring device 5 is an online moisture analyzer.

[0045] In this embodiment, the adsorption unit 3 may specifically include a first dehydration adsorption tower 31 and a second dehydration adsorption tower 32 arranged in series along the raw material flow direction. The adsorbent in the first dehydration adsorption tower 31 includes type A molecular sieve adsorbent and / or modified type A molecular sieve adsorbent, while the adsorbent in the second dehydration adsorption tower 32 includes metal ion-modified nano-ZSM-5 molecular sieve adsorbent and / or metal ion-modified nano-TS-1 molecular sieve adsorbent. Based on this, the inlet of the moisture measuring device 5 is connected to the outlets of both the first dehydration adsorption tower 31 and the second dehydration adsorption tower 32.

[0046] Furthermore, the aforementioned type A molecular sieve adsorbent can specifically be a 3A, 4A, or 5A molecular sieve, more preferably a spherical 3A molecular sieve. The preparation method of the modified type A molecular sieve adsorbent includes the following steps: mixing the type A molecular sieve and an acid solution for acid exchange to obtain an acid-modified type A molecular sieve. The acid solution preferably includes an aqueous solution of nitric acid or an aqueous solution of acetic acid, more preferably an aqueous solution of nitric acid; the molar concentration of the acid solution is preferably 0.05–10 mol / L, more preferably 0.1–5 mol / L; the solid-liquid ratio of the type A molecular sieve to the acid solution is preferably 1:1–50, more preferably 1:5–30; the acid exchange temperature is preferably 50–120℃, more preferably 60–100℃; the acid exchange time is preferably 8–48 h, more preferably 12–24 h.

[0047] Furthermore, in this embodiment, the adsorbent of the first dehydration adsorption tower 31 is preferably one of type A molecular sieve adsorbent and modified type A molecular sieve adsorbent, which can reduce the water content in the R134a raw material to about 15 ppm.

[0048] Furthermore, the preferred carrier for the aforementioned metal ion-modified nano-ZSM-5 molecular sieve adsorbent is a shaped ZSM-5 molecular sieve with a crystal size of 20–100 nm and a silicon-to-aluminum ratio of 20–100; the preferred carrier for the metal ion-modified nano-TS-1 molecular sieve adsorbent is a shaped TS-1 molecular sieve with a crystal size of 20–100 nm and a silicon-to-titanium ratio of 40–100. This scheme does not impose any particular limitation on the preparation methods of the nano-ZSM-5 molecular sieve carrier and the nano-TS-1 molecular sieve carrier; any preparation method known in the art can be used, such as the hydrothermal synthesis method for preparing nano-TS-1 molecular sieves or ZSM-5 molecular sieves disclosed in "Effect of treatment with different bases on the catalytic properties of TS-1 / SiO2 extrudates in propylene epoxidation" (Microporous and Mesoporous Materials, 2015, 212:48-55) or the invention patent with publication number CN102502696A. The nano-TS-1 or ZSM-5 molecular sieves can preferably be cylindrical, spherical, or clover-shaped, with cylindrical being more preferred. Preferably, the nano-TS-1 or ZSM-5 molecular sieves are prepared by mixing them with a binder using a molding machine to produce TS-1 or ZSM-5 molecular sieves of different shapes. The binder is preferably silica sol, and the mass ratio of the nano-molecular sieves to the binder is preferably 50–95:10–30, more preferably 60–80:15–25. There are no special requirements for the molding method; conventional methods in the art can be used, such as using an extrusion molding machine to prepare cylindrical TS-1 or ZSM-5 molecular sieves.

[0049] The preferred method for preparing metal ion-modified nanomolecular sieves includes the following steps: impregnating the shaped nanomolecular sieve with a metal salt solution to obtain metal ion-modified nanomolecular sieves. The metal salt solution is preferably zinc nitrate, zinc sulfate, zinc acetate, copper nitrate, or magnesium nitrate, more preferably zinc nitrate or magnesium nitrate; the concentration of the metal salt solution is preferably 0.01–10 mol / L, more preferably 0.05–5 mol / L; the metal loading is preferably 0.1–25%, more preferably 1%–15%; the solid-liquid ratio of the shaped nanomolecular sieve to the metal salt solution is preferably 1:1–20, more preferably 1:3–10; the impregnation temperature is preferably 40–100℃, more preferably 50–80℃; and the impregnation time is preferably 1–12 h, more preferably 2–8 h.

[0050] In this embodiment, the metal ion modified nano-molecular sieve in the second dehydration adsorption tower 32 preferably includes one of metal ion modified nano-ZSM-5 molecular sieve adsorbent and metal ion modified nano-TS-1 molecular sieve adsorbent, which can reduce the water content in R134a to ≤0.1ppm.

[0051] In this embodiment, the refrigerant R134a dehydration device 100 can be connected to an external R134a raw material supply source, or it can be specially configured with a raw material storage device 1. The raw material storage device 1 is connected to the inlet of the adsorption unit 3. The raw material storage device 1 is used to store R134a raw material and supply R134a raw material to the adsorption unit 3.

[0052] Furthermore, a flow meter 2 is installed between the inlet of the raw material storage device 1 and the adsorption unit 3 to facilitate real-time monitoring of the supply flow rate of R134a raw material.

[0053] In this embodiment, both the raw material storage device 1 and the aforementioned product collection device 6 are preferably collection bottles. This solution does not have any special limitations on the size and material of the collection bottle; conventional sizes and materials in the art can be used.

[0054] In this embodiment, as Figure 1 As shown, to facilitate the control of the flow and direction of R134a raw material within the R134a dehydration device 100, valves K1, K2, K3, K4, and K5 are respectively installed between the raw material storage device 1 and the flow meter 2, between the first dehydration adsorption tower 31 and the second dehydration adsorption tower 32, between the outlet of the first dehydration adsorption tower 31 and the inlet of the moisture measuring device 5, between the outlet of the second dehydration adsorption tower 32 and the inlet of the moisture measuring device 5, and between the outlet of the filtration system 4 and the product collection device 6. Valve K1, K2, K3, K4, and K5 are preferably solenoid valves.

[0055] In this embodiment, the filtration system 4 preferably uses an existing filter with a filter element precision of 0.1µm, the purpose of which is to remove particulate impurities introduced by the adsorbent. Both the filter and the online moisture analyzer are existing devices, and their specific structures and working principles will not be described in detail here.

[0056] The aforementioned refrigerant R134a dehydration device 100 can adsorb and dehydrate R134a raw material with a water content of 10-100 ppm to obtain R134a product with a water content ≤0.1 ppm (w%). The following example, using an R134a raw material with a water content of 70 ppm, and employing a type A molecular sieve adsorbent in the first dehydration adsorption tower 31 and a metal ion-modified nano ZSM-5 molecular sieve adsorbent (also known as nano zeolite molecular sieve) in the second dehydration adsorption tower 32, will specifically illustrate the refrigerant R134a dehydration process and principle implemented using the aforementioned refrigerant R134a dehydration device 100:

[0057] R134a feedstock with a water content of 70 ppm is introduced into adsorption unit 3 via flow meter 2. First, the first dehydration adsorption tower 31 uses type A molecular sieve adsorbent to reduce the water content from 70 ppm to 15 ppm. Then, the second dehydration adsorption tower 32 uses metal ion-modified nano-ZSM-5 molecular sieve adsorbent to reduce the water content from 15 ppm to ≤0.1 ppm. After passing the moisture measurement device 5, the product is finally processed by filtration system 4 to obtain R134a product with a water content ≤0.1 ppm (w%). The preferred weight hourly space velocity (WHSV) for introducing the R134a feedstock into adsorption unit 3 is 0.2–1.0 h⁻¹. -1 The first dehydration adsorption tower 31 has an adsorption temperature of room temperature, such as 0 to 35°C, and an adsorption pressure of 0.1 to 0.5 MPa; the second dehydration adsorption tower 32 has an adsorption temperature of room temperature, such as 0 to 35°C, and an adsorption pressure of 0.1 to 1.0 MPa.

[0058] In actual operation, before the R134a raw material is introduced into the adsorption unit 3, the first dehydration adsorption tower 31 and the second dehydration adsorption tower 32 can be purged and evacuated respectively by corresponding equipment. Generally, the purging temperature is 300-600℃ and the time is 12-24h; the evacuation time is 4-12h.

[0059] The aforementioned R134a dehydration device 100, by arranging two stages of dehydration adsorption towers in series in the adsorption unit 3, can continuously perform two-stage adsorption dehydration treatment on R134a raw material. The two-stage adsorption purification process efficiently removes water from the R134a raw material. After passing the online moisture analyzer test, an R134a product with a water content ≤0.1ppm (w%) can be collected. This R134a dehydration device is suitable for deep dehydration of R134a, employing adsorption dehydration with adsorbents, and offers advantages in energy saving and consumption reduction.

[0060] In addition, nano-zeolite molecular sieves have abundant pore structures and large specific surface areas. After being modified with metal ions, the electrostatic field effect in the zeolite pores is enhanced, which improves hydrophilicity and makes it more conducive to the adsorption and removal of water in R134a.

[0061] The dehydration effect of the above-mentioned refrigerant R134a dehydration device 100 is verified below with reference to embodiments and comparative examples:

[0062] Example 1

[0063] use Figure 1 The R134a dehydration device 100 shown adsorbs and removes water from the R134a raw material, which has a water content of 70 ppm.

[0064] The adsorbent in the first dehydration adsorption tower 31 is 3A molecular sieve.

[0065] The adsorbent in the second dehydration adsorption tower 32 is a zinc nitrate-modified nano ZSM-5 molecular sieve. The preparation method of the zinc nitrate-modified nano ZSM-5 molecular sieve is as follows: a shaped nano ZSM-5 molecular sieve with a silicon-to-aluminum ratio of 30 and a crystal size of 50 nm is mixed with a zinc nitrate solution with a molar concentration of 1.0 mol / L (solid-liquid ratio 1:4), impregnated at 80℃ for 6 h, filtered, dried at 110℃ for 12 h, and calcined at 540℃ for 6 h to obtain the zinc nitrate-modified nano ZSM-5 molecular sieve adsorbent.

[0066] The adsorbent in the adsorption unit 3 is activated using the purging unit 7 and the vacuuming unit 8. The gas used for purging the first dehydration adsorption tower 31 and the second adsorption dehydration adsorption tower 4 is high-purity nitrogen with a purity of 99.999%, the temperature is 400℃, and the purging time is 24h. After vacuuming the first dehydration adsorption tower 31 and the second adsorption dehydration adsorption tower 4 for 4h, the temperature is reduced to room temperature, for example, 0-35℃.

[0067] R134a raw material was fed at 0.6h -1 The R134a is fed into the first dehydration adsorption tower 31 at weight space velocity and undergoes the first stage of adsorption and dehydration under normal temperature and pressure conditions. After the first stage of adsorption and dehydration, the R134a enters the second dehydration adsorption tower 32 and undergoes the second stage of adsorption and dehydration under normal temperature and pressure conditions to obtain the dehydrated R134a product.

[0068] Example 2

[0069] The R134a raw material was dehydrated by adsorption according to the method in Example 1, except that the adsorbent in the second dehydration adsorption tower 32 was a copper nitrate modified nano ZSM-5 molecular sieve.

[0070] Example 3

[0071] The R134a raw material was dehydrated by adsorption according to the method of Example 1, except that the adsorbent in the second dehydration adsorption tower 32 was a magnesium nitrate modified nano ZSM-5 molecular sieve.

[0072] Example 4

[0073] The R134a raw material was dehydrated by adsorption according to the method in Example 1, except that the adsorbent in the second dehydration adsorption tower 32 was a zinc sulfate-modified nano ZSM-5 molecular sieve.

[0074] Example 5

[0075] The R134a raw material was dehydrated by adsorption according to the method in Example 1, except that the adsorbent in the second dehydration adsorption tower 32 was a zinc acetate modified nano ZSM-5 molecular sieve.

[0076] Comparative Example 1

[0077] Compared with the refrigerant R134a dehydration device 100 used in Example 1, the adsorption dehydration device used in Comparative Example 1 only has a first dehydration adsorption tower 31 in the adsorption unit 3, and no second dehydration adsorption tower 32; the water content in the R134a raw material is 70ppm.

[0078] The adsorbent in the first dehydration adsorption tower 31 is 3A molecular sieve.

[0079] The adsorbent in the adsorption unit 3 is activated by purging unit 7 and vacuuming unit 8. The gas used to purge the first dehydration adsorption tower 31 is high-purity nitrogen with a purity of 99.999%, the temperature is 400℃, and the purging time is 24h. After vacuuming the first dehydration adsorption tower 31 for 4h, it is cooled to room temperature, such as 0~35℃.

[0080] R134a raw material was fed at 0.6h -1 The weight space velocity is fed into the first dehydration adsorption tower 31, and adsorption and dehydration are carried out under normal temperature and pressure conditions to obtain the dehydrated R134a product.

[0081] Comparative Example 2

[0082] The R134a raw material was dehydrated by adsorption according to the method of Comparative Example 1, except that the adsorbent in the first dehydration adsorption tower 31 was 5A molecular sieve.

[0083] The water content in the dehydrated R134a products of Examples 1-5 and Comparative Examples 1 and 2 was detected using an online moisture analyzer, and the results are listed in Table 1.

[0084] Table 1. Water content in R134a products after adsorption and dehydration in Examples 1-5 and Comparative Examples 1 and 2.

[0085]

[0086] As can be seen from Table 1, the refrigerant R134a dehydration device 100 with a two-stage dehydration adsorption tower provided in this embodiment can effectively remove water from R134a raw material by adsorbing and removing water, and obtain R134a product with a water content ≤0.1ppm.

[0087] Example 2

[0088] like Figure 2 As shown, this embodiment provides a refrigerant R134a dehydration device 100, which, based on the first embodiment, is further provided with a purging unit 7 and a vacuum unit 8. The outlet of the purging unit 7 is connected to the inlet of the first dehydration adsorption tower 31 and the inlet of the second dehydration adsorption tower 32; the inlet of the vacuum unit 8 is connected to the inlet of the first dehydration adsorption tower 31 and the inlet of the second dehydration adsorption tower 32.

[0089] In this embodiment, as Figure 2 As shown, the vacuum unit 8 includes a vacuum buffer tank 81, a vacuum pump 82, and an exhaust gas treatment system 83 connected in sequence. The inlet of the vacuum buffer tank 81 is connected to the inlet of both the first dehydration adsorption tower 31 and the second dehydration adsorption tower 32. The vacuum buffer tank 81 is also directly connected to the exhaust gas treatment system 83. The exhaust gas treatment system 83 adopts existing technology, such as the Hercules Mini exhaust gas processor, the specific structure and working principle of which will not be described in detail here.

[0090] Based on the above solutions, such as Figure 2 As shown, in this embodiment, valves K6, K7, K8, K9, K10, and K11 are respectively installed between the outlet of the purging unit 7 and the inlet of the first dehydration adsorption tower 31, between the outlet of the purging unit 7 and the inlet of the second dehydration adsorption tower 32, between the inlet of the vacuum buffer tank 81 and the inlet of the first dehydration adsorption tower 31, between the inlet of the vacuum buffer tank 81 and the inlet of the second dehydration adsorption tower 32, between the vacuum buffer tank 81 and the tail gas treatment system 83, and between the vacuum pump 82 and the tail gas treatment system 83. Valves K6, K7, K8, K9, K10, and K11 are preferably solenoid valves.

[0091] The refrigerant R134a dehydration method implemented based on the above-mentioned refrigerant R134a dehydration device 100 includes the following steps:

[0092] R134a feedstock with a water content of 70 ppm is introduced into adsorption unit 3 via flow meter 2. First, the first dehydration adsorption tower 31 uses type A molecular sieve adsorbent to reduce the water content from 70 ppm to 15 ppm. Then, the second dehydration adsorption tower 32 uses metal ion-modified nano-ZSM-5 molecular sieve adsorbent to reduce the water content from 15 ppm to ≤0.1 ppm. After passing the moisture content test by moisture measuring device 5, the product is finally processed by filtration system 4 to obtain R134a product with a water content ≤0.1 ppm (w%). The preferred weight hourly space velocity (WHSV) for introducing the R134a feedstock into adsorption unit 3 is 0.05–1.2 h⁻¹. -1 More preferably, it is 0.2 to 0.8 h. -1 The first dehydration adsorption tower 31 has an adsorption temperature of room temperature, such as 0 to 35°C, and an adsorption pressure of 0.1 to 0.5 MPa; the second dehydration adsorption tower 32 has an adsorption temperature of room temperature, such as 0 to 35°C, and an adsorption pressure of 0.1 to 1.0 MPa.

[0093] In actual operation, before the R134a raw material is introduced into the adsorption unit 3, the first dehydration adsorption tower 31 and the second dehydration adsorption tower 32 of the adsorption unit 3 are purged and evacuated using the purging unit 7 and the vacuuming unit 8, respectively, to activate the adsorbent in the first dehydration adsorption tower 31 and the second dehydration adsorption tower 32. The purging gas used for the first dehydration adsorption tower 31 and the second dehydration adsorption tower 4 is high-purity nitrogen with a purity of 99.999%, the purging temperature is 300–500°C, and the purging time is 18–32 hours, more preferably 24–28 hours. The vacuuming time for the first dehydration adsorption tower 31 and the second dehydration adsorption tower 4 is preferably 2–8 hours, more preferably 4–6 hours.

[0094] The aforementioned R134a dehydration device 100, by arranging two stages of dehydration adsorption towers in series in the adsorption unit 3, can continuously perform two-stage adsorption dehydration treatment on R134a raw material. The two-stage adsorption purification process efficiently removes water from the R134a raw material. After passing the online moisture analyzer test, an R134a product with a water content ≤0.1ppm (w%) can be collected. This R134a dehydration device is suitable for deep dehydration of R134a, employing adsorption dehydration with adsorbents, and offers advantages in energy saving and consumption reduction.

[0095] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for dehydrating refrigerant R134a, characterized in that, The process employs a refrigerant R134a dehydration device, which includes an adsorption unit, a filtration system with its inlet connected to the outlet of the adsorption unit, and a product collection device with its inlet connected to the outlet of the filtration system. The adsorption unit comprises at least two dehydration adsorption towers connected in series along the raw material flow direction to perform at least two stages of adsorption and dehydration on the R134a raw material. The adsorption unit includes a first dehydration adsorption tower and a second dehydration adsorption tower connected in series along the raw material flow direction. The adsorbent in the first dehydration adsorption tower includes type A molecular sieve adsorbent and / or modified type A molecular sieve adsorbent. The adsorbent in the second dehydration adsorption tower includes metal ion-modified nano-ZSM-5 molecular sieve adsorbent and / or metal ion-modified nano-TS-1 molecular sieve adsorbent. The method for preparing the adsorbent in the second dehydration adsorption tower includes: impregnating a shaped nano-molecular sieve with a metal salt solution to obtain a metal ion modified nano-molecular sieve; wherein the concentration of the metal salt solution is 0.01~10 mol / L, the metal loading is 0.1~25%, the solid-liquid ratio of the shaped nano-molecular sieve to the metal salt solution is 1:1~20, the impregnation temperature is 40~100℃, and the impregnation time is 1~12h; The preparation method of the modified type A molecular sieve adsorbent set in the first dehydration adsorption tower includes: mixing type A molecular sieve and acid solution for acid exchange to obtain acid-modified type A molecular sieve; the molar concentration of the acid solution is 0.05~10 mol / L, the solid-liquid ratio of type A molecular sieve and acid solution is 1:1~50, the acid exchange temperature is 50~120℃, and the acid exchange time is 8~48h; Methods for dehydrating refrigerant R134a include: Before the R134a raw material is introduced into the adsorption unit, both the first dehydration adsorption tower and the second dehydration adsorption tower are purged and evacuated to activate the adsorbent in the first dehydration adsorption tower and the second dehydration adsorption tower; wherein, the purging gas is high-purity nitrogen with a purity of 99.999%, the purging temperature is 300~500℃, the purging time is 18~32h, and the evacuation time is 2~8h; R134a raw material is fed into the adsorption unit, and the first dehydration adsorption tower and the second dehydration adsorption tower respectively perform primary adsorption dehydration and secondary adsorption dehydration on the R134a raw material. The water content of the product at the outlet of the second dehydration adsorption tower is detected by a moisture measuring device until the water content of the product at the outlet of the second dehydration adsorption tower is ≤0.1ppm. Then the product at the outlet of the second dehydration adsorption tower is discharged into the product collection device for collection. The weight hourly space velocity (WHSV) of the R134a feedstock introduced into the adsorption unit is 0.05–1.2 h⁻¹. -1 The first dehydration adsorption tower has an adsorption temperature of room temperature and an adsorption pressure of 0.1~0.5MPa; the second dehydration adsorption tower has an adsorption temperature of room temperature and an adsorption pressure of 0.1~1.0MPa.

2. The method for dehydrating refrigerant R134a according to claim 1, characterized in that, The refrigerant R134a dehydration device also includes a moisture measuring device. The outlet of any of the dehydration adsorption towers is connected to the moisture measuring device, which is used to detect the water content of the outlet product of any of the dehydration adsorption towers.

3. The method for dehydrating refrigerant R134a according to claim 2, characterized in that, The refrigerant R134a dehydration device also includes a purging unit, and the inlet of any of the dehydration adsorption towers is connected to the outlet of the purging unit.

4. The method for dehydrating refrigerant R134a according to claim 2, characterized in that, The refrigerant R134a dehydration device also includes a vacuum unit, and the inlet of any of the dehydration adsorption towers is connected to the vacuum unit.

5. The method for dehydrating refrigerant R134a according to claim 4, characterized in that, The vacuum unit includes a vacuum buffer tank, a vacuum pump, and a tail gas treatment system connected in sequence. The inlet of the vacuum buffer tank is connected to the inlet of any of the dehydration adsorption towers, and the vacuum buffer tank is also directly connected to the tail gas treatment system.

6. The method for dehydrating refrigerant R134a according to any one of claims 1 to 5, characterized in that, The refrigerant R134a dehydration device also includes a raw material storage device connected to the inlet of the adsorption unit. The raw material storage device is used to store and supply R134a raw material to be dehydrated to the adsorption unit.

7. The method for dehydrating refrigerant R134a according to claim 6, characterized in that, It also includes a flow meter connected between the inlet of the adsorption unit and the raw material storage device.

Images