Purification method and device for preparing high-purity propane through low-pressure method

Abstract

The invention relates to a purification method and device for preparing high-purity propane by a low-pressure method. The method comprises the following steps: pressing a crude product raw material with the purity of 99% into a first-stage rectifying tower by a low-pressure rectifying method, enabling the material to form reflux in the tower through a tower top condenser and a tower kettle heater, removing light component impurities such as hydrogen, oxygen, nitrogen, methane, carbon monoxide and propylene at the tower top, and transferring the material to a second-stage rectifying tower after the material is sampled to be qualified by the first-stage rectifying tower; materials are refluxed in the tower through a tower top condenser and a tower kettle heater, and heavy components such as isobutane and the like are mainly removed; after being analyzed and detected to be qualified at the tower top, the gas enters a product storage tank, and tail gas generated by light-component impurities, unqualified gas and the like passes through an alkaline tower and is discharged into a three-waste collector after reaching the standard. Based on the purification device and the purification method, propane with the purity of 99.9997% can be obtained, and the method is simple, convenient to operate, energy-saving, environment-friendly and good in purification effect.

Description

Technical Field

[0001] The invention relates to the technical field of propane purification for semiconductor industry, and in particular to a purification method and device for preparing high-purity propane by a low-pressure method. Background Art

[0002] Propane is a colorless gas, odorless in pure form, flammable, and produces a bright flame when burned. At present, high-purity propane is widely used. It is not only the raw material for optoelectronic components, but also an important component in the gas distribution process. With the development of the optoelectronics industry in the semiconductor industry, the purity requirements are particularly high, and the demand for high-purity propane is also increasing. However, the boiling point of propane is -42.1℃, and the boiling point of propylene is -47.7℃. The difference between the boiling points of the two is small, so it is particularly important to remove propylene from propane. Commonly used methods include absorption separation, membrane separation and distillation.

[0003] Absorption separation is a method of selective separation using the difference in solubility of propane and propylene in the absorbent. Chinese patent publication number CN102795956B discloses a method for separating the reaction products of propane dehydrogenation to propylene. The reaction products of propane dehydrogenation to propylene are separated by combining membrane separation and cryogenic separation. However, the recovery rate of membrane separation is low and the total energy consumption is not reduced.

[0004] The membrane separation method is a means of separating a mixture by utilizing the difference in permeation rates of the components of the mixture to be separated through a membrane under the action of a pressure difference. A Chinese patent with the announcement number CN111747818B discloses a propylene / propane separation method. The patent uses a modified molecular sieve modified with an imidazole compound for selective adsorption separation of propane and propylene. Although propane and propylene can be separated, the adsorbent cost is high, the selectivity is not high, and the adsorption amount is small, and it still does not have the possibility of industrial application.

[0005] The Chinese patent with the announcement number CN116603258A discloses a system and method for separating and preparing high-purity propane and high-purity propylene, which mainly uses a pre-reactor, a storage tank, a catalytic distillation tower, a catalytic cracking distillation tower and a heat exchanger to first cause propylene to undergo etherification reaction in the pre-reactor, and then the remaining propylene undergoes etherification reaction in the catalytic distillation tower, and high-purity propane is obtained by separation at the top of the tower; the materials in the bottom of the tower enter the catalytic cracking distillation tower for catalytic cracking reaction, and high-purity propylene is obtained by separation at the top of the tower. However, the purity of the propane product of this method needs to be further improved.

[0006] In summary, the existing technology has the problems of high propane purification cost, complex process, low separation efficiency, and low product purity. It is urgent to propose a propane purification method with simple process, low cost, high separation efficiency and high product purity to solve the current problems. Summary of the invention

[0007] In view of the problems existing in the prior art of high propane purification cost, complex process, low separation efficiency, and low product purity, the present application proposes a purification method and device for preparing high-purity propane by a low-pressure method.

[0008] The technical solution of this application:

[0009] On the one hand, the present application provides a purification method for preparing high-purity propane by a low-pressure method, comprising the following steps:

[0010] Step S1. The crude propane product is subjected to primary distillation to remove light components in the crude product to obtain a primary distillate, and the light components are alkali washed to meet emission requirements;

[0011] Step S2: subjecting the primary distillate to secondary distillation to remove heavy components in the primary distillate to obtain high-purity propane, and alkali washing the heavy components to meet emission requirements.

[0012] Preferably, the reflux ratio in the primary distillation in step S1 is 20-35, the temperature is -5-20°C, the pressure is 0.3-0.7 MPa, and the time is not less than 2 hours; the light components are hydrogen, oxygen, nitrogen, methane, carbon monoxide and propylene.

[0013] Preferably, in the step S2, the reflux ratio in the secondary distillation is 20-35, the temperature is -14-15°C, the pressure is 0.2-0.6 MPa, and the time is not less than 2 hours; the recombinant fraction is isobutane.

[0014] Preferably, the alkali washing solution in step S1 and step S2 is any one of sodium hydroxide, potassium hydroxide and calcium hydroxide.

[0015] On the other hand, the present application provides a purification device for preparing high-purity propane by a low-pressure method, comprising a primary distillation tower, wherein a first heater is provided at the lower end of the primary distillation tower, and a first condenser is provided at the upper end; the upper part of the primary distillation tower is connected to an alkali washing tower through a first pipeline, and the lower part is connected to a secondary distillation tower through a second pipeline; the lower end of the secondary distillation tower is provided with a second heater, and the upper end is provided with a second condenser, the upper part of the secondary distillation tower is connected to a product storage tank through a third pipeline, and the lower part is connected to the alkali washing tower through a fourth pipeline.

[0016] Preferably, the alkali washing tower is also connected to the three-waste collector through a fifth pipeline, and a fifth valve is provided on the fifth pipeline.

[0017] Preferably, a crude product inlet is further provided on the side of the primary distillation tower for the crude product to enter the primary distillation tower.

[0018] Preferably, a first sampling port is further provided at the lower portion of the primary distillation tower, and a second sampling port is further provided at the upper portion of the secondary distillation tower; and the number of plates of the primary distillation tower and the secondary distillation tower is 45-90.

[0019] Preferably, the first pipeline is provided with a first valve; the second pipeline is provided with a second valve; the third pipeline is provided with a third valve; and the fourth pipeline is provided with a fourth valve.

[0020] Beneficial effects of this application:

[0021] The present application uses a low-pressure method to control the pressure of the first-stage distillation to 0.3-0.7 MPa, and efficiently separates the light component propylene in the first-stage distillation tower, solving the problem of low efficiency and low product purity of separating propylene and propane by traditional methods. The purification device of the present application is mainly composed of a first-stage distillation tower, a second-stage distillation tower, an alkali washing tower, a product storage tank, etc. The connection between each component is clear and easy to operate, which reduces the complexity and difficulty of the equipment and improves production efficiency and stability. The present application can control the purification process of propane by two-stage distillation, effectively remove light components and heavy components in the crude product, and reduce energy consumption and waste emissions. At the same time, an alkali washing tower is set to recycle and treat light components and heavy components, which reduces environmental pollution and meets the requirements of green production. The purification method of the present application can efficiently remove light components and heavy components in the crude propane product by controlling the process parameters, reflux ratio, temperature, pressure and time of the two-stage distillation, and obtain a high-purity propane product. The device of the present application is simple and can realize industrial production. At the same time, it provides a design idea for the purification of other gas products, and can be tried in other gas purification fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention discloses a purification device for preparing high-purity propane by a low-pressure method.

[0023] Figure numerals: 1, primary distillation tower; 2, first heater; 3, first condenser; 4, secondary distillation tower; 5, second heater; 6, second condenser; 7, product storage tank; 8, alkali washing tower; 9, three wastes collector; 10, crude product inlet; 11, first sampling port; 12, second valve; 13, second pipeline; 14, first pipeline; 15, first valve; 16, fifth valve; 17, fifth pipeline; 18, second sampler; 19, third valve; 20, third pipeline; 21, fourth valve; 22, fourth pipeline. DETAILED DESCRIPTION

[0024] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0025] Example 1

[0026] This embodiment provides a purification device for preparing high-purity propane by a low-pressure method, such as Figure 1As shown,

[0027] The invention comprises a primary distillation tower 1, wherein a first heater 2 is arranged at the lower end of the primary distillation tower 1, a first condenser 3 is arranged at the upper end, the upper part of the primary distillation tower 1 is connected with an alkali washing tower 8 through a first pipeline 14, and the lower part is connected with a secondary distillation tower 4 through a second pipeline 13; a second heater 5 is arranged at the lower end of the secondary distillation tower 4, a second condenser 6 is arranged at the upper end, the upper part of the secondary distillation tower 4 is connected with a product storage tank 7 through a third pipeline 20, and the lower part is connected with the alkali washing tower 8 through a fourth pipeline 22.

[0028] Furthermore, the alkali washing tower 8 is also connected to the three-waste collector 9 through a fifth pipeline 17 .

[0029] Furthermore, a crude product inlet 10 is provided on the side of the primary distillation tower 1 for the crude product to enter the primary distillation tower 1 .

[0030] Furthermore, a first sampling port 11 is provided at the lower portion of the primary distillation tower 1 , and a second sampling port 18 is provided at the upper portion of the secondary distillation tower 4 .

[0031] Valves are provided on the first pipeline 14 , the second pipeline 13 , the third pipeline 20 , the fourth pipeline 22 and the fifth pipeline 17 .

[0032] Example 2

[0033] Based on the purification device for preparing high-purity propane by a low-pressure method provided in Example 1, this example provides a purification method for preparing high-purity propane by a low-pressure method. The number of plates of the first distillation tower and the second distillation tower in this example is 45.

[0034] The crude propane with a purity of 99% is introduced into the primary distillation tower 1 through the crude product inlet 10 under the action of pressure, the first heater 2 and the first condenser 3 are turned on, the temperature of the primary distillation tower 1 is adjusted to 20°C and the pressure is 0.7MPa, and under the action of the first heater 2 and the first condenser 3, the logistics in the primary distillation tower 1 is refluxed, and the reflux ratio is controlled to be 30. After the temperature and pressure of the primary distillation tower 1 are kept stable for 2 hours, the first valve 15 is opened, and hydrogen, oxygen, nitrogen, methane, and carbon monoxide are discharged from the top of the tower. , propylene light component impurities enter the alkaline washing tower 8 along the first pipeline 14, and the light component gas is absorbed under the action of sodium hydroxide with a concentration of 5 mol / L. After reaching the standard, the fifth valve 16 is opened, and other impurities insoluble in alkaline solution enter the three-waste collector 9 through the fifth pipeline 17; and through the first sampling port 11, sampling is performed to detect the purity of the primary distillate. When the product purity is qualified, the first valve 15 is closed, the second valve 12 is opened, and the gas enters the secondary distillation tower 4 through the second pipeline 13.

[0035] Open the second heater 5 and the second condenser 6 in the secondary distillation tower 4, adjust the temperature of the secondary distillation tower 4 to 15°C and the pressure to 0.6MPa, and under the action of the second heater 5 and the second condenser 6, the primary distillate forms reflux in the secondary distillation tower 4, and the reflux ratio is controlled to be 20-35. After the temperature and pressure positions of the secondary distillation tower 4 are stabilized for 2 hours, sample and detect through the second sampling port 18. When the purity of the product is 99.9993%, open the third valve 19, and the product enters the product storage tank 7 through the third pipeline 20. Finally, open the fourth valve 21, and the isobutane heavy component enters the alkali washing tower 8 through the fourth pipeline 22, and enters the three waste collector 9 after meeting the standards.

[0036] Example 3

[0037] Based on the purification device for preparing high-purity propane by a low-pressure method provided in Example 1, this example provides a purification method for preparing high-purity propane by a low-pressure method. The number of plates of the first distillation tower and the second distillation tower in this example is 70.

[0038] The crude propane with a purity of 99% is introduced into the primary distillation tower 1 through the crude product inlet 10 under the action of pressure, the first heater 2 and the first condenser 3 are turned on, the temperature of the primary distillation tower 1 is adjusted to 8°C and the pressure is 0.5MPa, and under the action of the first heater 2 and the first condenser 3, the logistics in the primary distillation tower 1 is refluxed, and the reflux ratio is controlled to be 20. After the temperature and pressure of the primary distillation tower 1 are kept stable for 2 hours, the first valve 15 is opened, and hydrogen, oxygen, nitrogen, methane, and carbon monoxide are discharged from the top of the tower. , propylene light component impurities enter the alkaline washing tower 8 along the first pipeline 14, and the light component gas is absorbed under the action of calcium hydroxide with a concentration of 3 mol / L. After reaching the standard, the fifth valve 16 is opened, and other impurities insoluble in alkaline solution enter the three-waste collector 9 through the fifth pipeline 17; and through the first sampling port 11, sampling is performed to detect the purity of the primary distillate. When the product purity is qualified, the first valve 15 is closed, the second valve 12 is opened, and the gas enters the secondary distillation tower 4 through the second pipeline 13.

[0039] Open the second heater 5 and the second condenser 6 in the secondary distillation tower 4, adjust the temperature of the secondary distillation tower 4 to 2°C and the pressure to 0.4 MPa, and under the action of the second heater 5 and the second condenser 6, the primary distillate forms reflux in the secondary distillation tower 4, and the reflux ratio is controlled to be 20-35. After the temperature and pressure positions of the secondary distillation tower 4 are stabilized for 2 hours, sample and detect through the second sampling port 18. When the purity of the product is 99.9995%, open the third valve 19, and the product enters the product storage tank 7 through the third pipeline 20. Finally, open the fourth valve 21, and the isobutane heavy component enters the alkali washing tower 8 through the fourth pipeline 22, and enters the three waste collector 9 after reaching the standard.

[0040] Example 4

[0041] Based on the purification device for preparing high-purity propane by a low-pressure method provided in Example 1, this example provides a purification method for preparing high-purity propane by a low-pressure method. The number of plates of the first distillation tower and the second distillation tower in this example is 90.

[0042] The crude propane with a purity of 99% is introduced into the primary distillation tower 1 through the crude product inlet 10 under the action of pressure, the first heater 2 and the first condenser 3 are turned on, the temperature of the primary distillation tower 1 is adjusted to -5°C and the pressure is 0.3MPa, and under the action of the first heater 2 and the first condenser 3, the logistics in the primary distillation tower 1 is refluxed, and the reflux ratio is controlled to be 30. After the temperature and pressure of the primary distillation tower 1 are kept stable for 2 hours, the first valve 15 is opened, and hydrogen, oxygen, nitrogen, methane, and carbon monoxide are discharged from the top of the tower. , propylene light component impurities enter the alkaline washing tower 8 along the first pipeline 14, and the light component gas is absorbed under the action of potassium hydroxide with a concentration of 5 mol / L. After reaching the standard, the fifth valve 16 is opened, and other impurities insoluble in alkaline solution enter the three-waste collector 9 through the fifth pipeline 17; and through the first sampling port 11, sampling is performed to detect the purity of the primary distillate. When the product purity is qualified, the first valve 15 is closed, the second valve 12 is opened, and the gas enters the secondary distillation tower 4 through the second pipeline 13.

[0043] Open the second heater 5 and the second condenser 6 in the secondary distillation tower 4, adjust the temperature of the secondary distillation tower 4 to -14°C and the pressure to 0.2MPa, under the action of the second heater 5 and the second condenser 6, the primary distillate forms reflux in the secondary distillation tower 4, and the reflux ratio is controlled to be 20-35. After the temperature and pressure positions of the secondary distillation tower 4 are stabilized for 2 hours, sampling and detection are performed through the second sampling port 18. When the purity of the product is 99.9997%, open the third valve 19, and the product enters the product storage tank 7 through the third pipeline 20. Finally, open the fourth valve 21, and the isobutane heavy component enters the alkali washing tower 8 through the fourth pipeline 22, and enters the three waste collector 9 after meeting the standards.

[0044] Comparative Example 1

[0045] The main difference between this comparative example and Example 4 is that the pressure of the primary distillation tower in this comparative example is set to 1 MPa, and the purity of the final detected product is 99.6888%.

[0046] Comparative Example 2

[0047] The main difference between this comparative example and Example 4 is that the pressure of the primary distillation tower in this comparative example is set to 0 MPa, and the purity of the final detected product is 99.5555%.

[0048] Comparative Example 3

[0049] The main difference between this comparative example and Example 4 is that the temperature of the primary distillation tower in this comparative example is 25° C., and the purity of the final detected product is 99.5127%.

[0050] Comparative Example 4

[0051] The main difference between this comparative example and Example 4 is that the temperature of the primary distillation tower in this comparative example is -10°C, and the purity of the final detected product is 99.4623%.

[0052] In summary, the propane purification device and purification method based on the present application effectively remove light components and heavy components in the crude product, and the purity of the final product is above 99.9993%, while the pressure of Comparative Example 1 and Comparative Example is higher than or lower than the pressure range of the present application, and it is difficult to separate propylene from propane. Although the pressure of Comparative Example 3 and Comparative Example 4 is within the scope of the present application, the temperature is adjusted, and the temperature is higher or lower than the temperature range of the present application. Due to the inappropriate temperature, the hydrogen components including propylene in the product may be difficult to separate from the crude propane product, and directly enter the secondary distillation with the primary distillate, resulting in the product obtained by the secondary distillation containing more light components. Therefore, based on the purification method and purification device provided by the present application, the crude propane product can be effectively purified, and components such as propylene can be efficiently separated, and the operation of the present application is simple, which reduces the complexity and difficulty of the equipment and improves the production efficiency and stability. The present application is provided with an alkali washing device to treat the generated waste gas, reduce environmental pollution, and meet the requirements of green production.

[0053] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A purification method for preparing high-purity propane by a low-pressure method, It is characterized in that The steps include: Step S1. The crude propane product is subjected to primary distillation to remove light components in the crude product to obtain a primary distillate, and the light components are alkali washed to meet emission requirements; Step S2: subjecting the primary distillate to secondary distillation to remove heavy components in the primary distillate to obtain high-purity propane, and alkali washing the heavy components to meet emission requirements.

2. A purification method for preparing high-purity propane by a low-pressure method according to claim 1, It is characterized in that In the step S1, the reflux ratio in the primary distillation is 20-35, the temperature is -5-20°C, the pressure is 0.3-0.7MPa, and the time is not less than 2h; the light components are hydrogen, oxygen, nitrogen, methane, carbon monoxide and propylene.

3. The method for purifying high-purity propane prepared by a low-pressure method according to claim 1, It is characterized in that In the step S2, the reflux ratio in the secondary distillation is 20-35, the temperature is -14-15°C, the pressure is 0.2-0.6MPa, and the time is not less than 2h; the recombinant fraction is isobutane.

4. The method for preparing high-purity propane by a low-pressure purification method according to claim 1, It is characterized in that The alkali washing solution in step S1 and step S2 is any one of sodium hydroxide, potassium hydroxide and calcium hydroxide.

5. A purification device for preparing high-purity propane by a low-pressure method, based on the purification method according to any one of claims 1 to 4, It is characterized in that The invention comprises a primary distillation tower (1), wherein a first heater (2) is provided at the lower end of the primary distillation tower (1), and a first condenser (3) is provided at the upper end; the upper part of the primary distillation tower (1) is connected to an alkali washing tower (8) through a first pipeline (14), and the lower part is connected to a secondary distillation tower (4) through a second pipeline (13); the lower end of the secondary distillation tower (4) is provided with a second heater (5), and the upper end is provided with a second condenser (6); the upper part of the secondary distillation tower (4) is connected to a product storage tank (7) through a third pipeline (20), and the lower part is connected to the alkali washing tower (8) through a fourth pipeline (22).

6. A purification device for preparing high-purity propane by a low-pressure method according to claim 5, It is characterized in that The alkali washing tower (8) is also connected to the three wastes collector (9) through a fifth pipeline (17), and a fifth valve (16) is provided on the fifth pipeline (17).

7. A purification device for preparing high-purity propane by a low-pressure method according to claim 5, It is characterized in that The side of the primary distillation tower (1) is also provided with a crude product inlet (10) for the crude product to enter the primary distillation tower (1).

8. A purification device for preparing high-purity propane by a low-pressure method according to claim 5, It is characterized in that The first distillation tower (1) is also provided with a first sampling port (11) at the bottom, and the second distillation tower (4) is also provided with a second sampling port (18) at the top; the number of plates of the first distillation tower (1) and the second distillation tower (4) is 45 to 90.

9. A purification device for preparing high-purity propane by a low-pressure method according to claim 5, It is characterized in that The first pipeline (14) is provided with a first valve (15); the second pipeline (13) is provided with a second valve (12); the third pipeline (20) is provided with a third valve (19); and the fourth pipeline (22) is provided with a fourth valve (21).

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