Mixed gas multi-stage condensing device

Abstract

The utility model provides a multi-stage condensing device for mixed gas, which comprises more than two stages of condensers which are sequentially connected in series and are used for condensing and separating the mixed gas to be treated. And an air outlet of the last-stage condenser is connected to a refrigerant inlet of any stage of condenser which is more preceding than the last-stage condenser through a pipeline to provide cooling capacity for the last-stage condenser. Compared with an existing condensation recovery device, the mixed gas multi-stage condensation device can utilize the cooling capacity of the gas separated by the last-stage condenser, and has lower energy consumption.

Description

Technical Field

[0001] The utility model relates to a multi-stage condensation recovery device, in particular to a multi-stage condensation device for a chlorosilane mixed gas. Background Art

[0002] Polysilicon is the most important and basic functional material for the semiconductor and solar photovoltaic cell industries. Trichlorosilane is one of the main raw materials for the production of polysilicon products. It is currently mainly produced by the cold hydrogenation process of silicon tetrachloride. The process principle of the cold hydrogenation process of silicon tetrachloride to produce trichlorosilane is: the raw silicon powder, hydrogen, silicon tetrachloride copper-based or nickel-based catalyst, gas-solid fluidization reaction occurs in a fluidized bed reactor, and trichlorosilane is synthesized at a certain temperature and pressure. The main reaction formula is: Si+2H2+3SiCl4=4SiHCl3, the reaction temperature is 500-550℃, and the reaction pressure is 2-3Mpa. The chlorosilane mixed gas obtained by the reaction in the fluidized bed reactor mainly includes trichlorosilane, dichlorodihydrosilane, unreacted silicon tetrachloride, hydrogen and fine silicon powder. The chlorosilane mixed gas containing fine silicon powder is first cooled in a quenching tower to obtain a mixed gas to be treated. The mixed gas to be treated flows out through the top outlet of the quenching tower to a mixed gas multi-stage condensing device. The mixed gas to be treated is condensed and recovered by a condensation recovery device to form a chlorosilane solution. The chlorosilane solution is then subjected to processes such as rough separation and distillation to separate a high-purity trichlorosilane product.

[0003] The current mixed gas multi-stage condensation device includes an air cooler, a water cooler and a Freon condenser connected in sequence. The mixed gas to be treated is condensed and recovered in three stages by the air cooler, the water cooler and the Freon condenser to form the above-mentioned chlorosilane solution, and the obtained non-condensable gas is directly discharged, which has the defect of wasting cold. In addition, the device completely relies on an external cold source, has the disadvantages of high energy consumption and poor condensation effect.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the utility model, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to ordinary technicians in this field. Utility Model Content

[0005] Purpose of the utility model: The technical problem to be solved by the utility model is to provide a mixed gas multi-stage condensation device for the deficiencies in the prior art, which can condense and separate chlorosilane solution and has lower energy consumption and better condensation effect.

[0006] In order to solve the above technical problems, the utility model provides a mixed gas multi-stage condensation device, which is characterized by comprising:

[0007] Two or more stages of condensers arranged in series;

[0008] A degassing storage tank, wherein the degassing storage tank can be configured to receive and degas the final liquid separated product containing non-condensable gas obtained by condensation of the last condenser in the two or more condensers to obtain the non-condensable gas;

[0009] And a non-condensable gas return pipeline, the gas outlet of the degassing storage tank is connected to the refrigerant inlet of any one of the more than two-stage condensers that is earlier than the last-stage condenser through the non-condensable gas return pipeline, so as to allow the non-condensable gas to pass through the earlier condenser to provide cooling for it.

[0010] Preferably, the gas outlet of the last-stage condenser is connected to the refrigerant inlet of the first-stage condenser in the condensers with more than two stages through the non-condensable gas return pipeline to provide cooling capacity therefor.

[0011] Specifically, the condenser with more than two stages is provided with three stages, including:

[0012] A primary condenser, used for performing a first condensation on the mixed gas to be treated to obtain a first liquid separated product and a mixed gas from which the first liquid separated product has been separated;

[0013] A secondary condenser, used for performing a second condensation on the mixed gas from which the first liquid separated product has been separated, to obtain a mixed gas of the second liquid separated product and the separated second liquid separated product;

[0014] and a three-stage condenser for condensing the mixed gas from which the second liquid separated product has been separated for the third time to obtain the final liquid separated product containing the non-condensable gas.

[0015] Specifically, the mixed gas to be treated includes trichlorosilane, dichlorosilane, silicon tetrachloride and hydrogen, and the non-condensable gas is hydrogen.

[0016] Specifically, the refrigerant of the secondary condenser is ethylene glycol.

[0017] Specifically, the refrigerant of the three-stage condenser is Freon.

[0018] Specifically, the temperature of the secondary condenser is lower than that of the primary condenser. The temperature of the tertiary condenser is lower than that of the secondary condenser.

[0019] Furthermore, it also includes a quenching tower, which is used to quench the chlorosilane mixed gas generated by the fluidized bed reactor to obtain the mixed gas to be treated.

[0020] Specifically, the air inlet of the primary condenser is used for the mixed gas to be treated to pass through, the air outlet of the primary condenser is connected to the air inlet of the secondary condenser, and the air outlet of the secondary condenser is connected to the air inlet of the tertiary condenser.

[0021] Specifically, the liquid outlet of the primary condenser and the liquid outlet of the secondary condenser are both connected to the degassing storage tank.

[0022] Beneficial effects:

[0023] 1) Compared with the prior art which directly discharges the non-condensable gas, the mixed gas multi-stage condensing device provided by the utility model can utilize the cold energy of the non-condensable gas, avoid the waste of cold energy, and has lower energy consumption.

[0024] 2) When the mixed gas multi-stage condensation device provided by the utility model is specifically composed of a first-stage condenser using non-condensable gas as the refrigerant, a second-stage condenser using ethylene glycol as the refrigerant, and a third condenser using Freon as the refrigerant, the mixed gas multi-stage condensation device has a better condensation effect than the existing device composed of an air cooler, a water cooler and a Freon condenser. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods, and the above and / or other advantages of the present invention will become more clear.

[0026] Figure 1 The present invention is a schematic structural diagram of a mixed gas multi-stage condensation device according to an embodiment of the present invention.

[0027] The description of the accompanying drawings is:

[0028] A primary condenser 1, a secondary condenser 2, a tertiary condenser 3, a quench tower 4 and a degassing storage tank 5. DETAILED DESCRIPTION

[0029] The current mixed gas multi-stage condensation device includes an air cooler, a water cooler and a Freon condenser connected in sequence. The mixed gas to be treated is condensed and recovered in three stages by the air cooler, the water cooler and the Freon condenser to form the above-mentioned chlorosilane solution, and the obtained non-condensable gas is directly discharged.

[0030] The inventors found that the existing device completely relies on an external cold source, and has the disadvantages of high energy consumption and poor condensation effect. The inventors also found that in the existing device, the non-condensable gas obtained is directly discharged, resulting in the waste of its cold capacity.

[0031] Therefore, the utility model provides a mixed gas multi-stage condensation device, which includes more than two stages of condensers arranged in series, and is used for condensing and separating the mixed gas to be processed.

[0032] The device comprises a degassing storage tank 5, which can be configured to receive and degas the final liquid separated product containing non-condensable gas obtained by condensation of the last condenser in the two or more condensers, to obtain the non-condensable gas.

[0033] The device includes a non-condensable gas reflux pipeline, and the gas outlet of the degassing storage tank 5 is connected to the refrigerant inlet of any one of the more than two-stage condensers that is earlier than the last-stage condenser through the non-condensable gas reflux pipeline, so as to allow the non-condensable gas to pass through the earlier condenser to provide cooling for it.

[0034] Compared with the existing condensation recovery device, the mixed gas multi-stage condensation device can use the non-condensable gas to provide cooling capacity for the condenser at the previous stage, and has lower energy consumption.

[0035] Preferably, the gas outlet of the last-stage condenser is connected to the refrigerant inlet of the first-stage condenser in the condenser with more than two stages through a non-condensable gas return pipeline to provide cooling capacity therefor.

[0036] Example 1

[0037] In this embodiment, the chlorosilane mixed gas generated by the reaction in the fluidized bed reactor is quenched in a quench tower 4 to obtain the mixed gas to be treated. Specifically, the mixed gas to be treated includes trichlorosilane, dichlorosilane, silicon tetrachloride and hydrogen, wherein trichlorosilane, dichlorosilane and silicon tetrachloride constitute condensable gas, and non-condensable gas includes hydrogen.

[0038] In this embodiment, the condenser with more than two stages is provided with three stages, including a first-stage condenser 1, a second-stage condenser 2 and a third-stage condenser 3. The first-stage condenser 1 is used as a first-stage condenser for performing the first condensation on the mixed gas to be treated to obtain a first liquid separation and a mixed gas from which the first liquid separation has been separated. The second-stage condenser 2 is used for performing a second condensation on the mixed gas from which the first liquid separation has been separated to obtain a second liquid separation and a mixed gas from which the second liquid separation has been separated. The third-stage condenser 3 is used as a final-stage condenser for performing a third condensation on the mixed gas from which the second liquid separation has been separated to obtain a final-stage liquid separation containing non-condensable gas.

[0039] It should be understood that, according to the difference in boiling points of the components of the condensable gas, the condenser with more than two stages may be provided with more stages to more effectively condense and separate the different components.

[0040] Specifically, the temperature of the secondary condenser 2 is lower than that of the primary condenser 1. The temperature of the tertiary condenser 3 is lower than that of the secondary condenser 2. Preferably, the temperature of the primary condenser 1 is configured to be 20° to 45°, the temperature of the secondary condenser 2 is configured to be -10° to 15°, and the temperature of the tertiary condenser 3 is configured to be -40° to -30°.

[0041] The first liquid separation, the second liquid separation and the final liquid separation all include trichlorosilane, dichlorosilane and silicon tetrachloride, but the corresponding weight percentages are different. Since the specific weight percentages of the first liquid separation, the second liquid separation and the final liquid separation do not involve the main improvement points of the present application, they are not described here.

[0042] Specifically, the refrigerant of the secondary condenser 2 is ethylene glycol.

[0043] Specifically, the refrigerant of the tertiary condenser 3 is Freon.

[0044] Furthermore, the device also includes a quenching tower 4, which is used to quench the chlorosilane mixed gas generated by the fluidized bed reactor to remove fine silicon powder and obtain the mixed gas to be treated.

[0045] Specifically, the air inlet of the first-stage condenser 1 is used for the introduction of the mixed gas to be treated, the air outlet of the first-stage condenser 1 is connected to the air inlet of the second-stage condenser 2, the air outlet of the second-stage condenser 2 is connected to the air inlet of the third-stage condenser 3, and the air outlet of the third-stage condenser 3 is connected to the refrigerant inlet of the first-stage condenser 1.

[0046] Specifically, the liquid outlet of the tertiary condenser 3 is used to supply the final liquid separation containing non-condensable gas to flow out. The liquid outlet of the primary condenser 1 and the liquid outlet of the secondary condenser 2 are used to supply the first liquid separation and the second liquid separation to flow out, respectively. The liquid outlet of the primary condenser 1, the liquid outlet of the secondary condenser 2 and the liquid outlet of the tertiary condenser 3 are all connected to the liquid inlet of the degassing storage tank 5.

[0047] Below, refer to Figure 1 , the method of using the mixed gas multi-stage condensing device of the utility model shown in embodiment 1 in the condensation recovery process is explained.

[0048] The chlorosilane mixed gas flowing out from the outlet of the fluidized bed reactor is washed and cooled in the quench tower 4, and the fine silicon powder entrained in the chlorosilane mixed gas is removed to obtain the mixed gas to be treated; the mixed gas to be treated flows out from the outlet at the top of the quench tower 4 to the air inlet of the primary condenser 1, and the non-condensable gas from the degassing storage tank 5 flows into the refrigerant inlet of the primary condenser 1 to provide cooling capacity to the primary condenser. After the mixed gas to be treated exchanges heat with the non-condensable gas, a first liquid separation is obtained; the mixed gas from which the first liquid separation is separated flows into the air inlet of the secondary condenser 2, and the mixed gas from which the first liquid separation is separated exchanges heat with the refrigerant ethylene glycol in the shell side of the secondary condenser 2 to obtain a second liquid separation; the mixed gas from which the second liquid separation is separated flows into the air inlet of the tertiary condenser 3, and the mixed gas from which the second liquid separation is separated exchanges heat with the refrigerant Freon in the shell side of the tertiary condenser 3 to obtain a final liquid separation containing non-condensable gas, wherein the non-condensable gas is hydrogen. The first, second and final liquid separations containing non-condensable gas all flow into the degassing storage tank 5 for storage and degassing treatment. The degassed liquid separations will subsequently be supplied to the coarse separation tower and the distillation tower to separate high-purity trichlorosilane products.

[0049] The utility model provides a concept and method of a mixed gas multi-stage condensing device. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the utility model. These improvements and modifications should also be regarded as the protection scope of the utility model. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A mixed gas multi-stage condensation device, characterized in that: include: Two or more stages of condensers arranged in series; A degassing storage tank (5), wherein the degassing storage tank (5) can be configured to receive and degas a final liquid separation containing non-condensable gas obtained by condensation of the last condenser in the two or more condensers, to obtain the non-condensable gas; and a non-condensable gas return pipeline, wherein the gas outlet of the degassing storage tank (5) is connected to the refrigerant inlet of any one of the two or more condensers that is earlier than the last condenser through the non-condensable gas return pipeline, so as to allow the non-condensable gas to pass through the earlier condenser to provide cooling for it.

2. The mixed gas multi-stage condensation device according to claim 1, characterized in that: The gas outlet of the last-stage condenser is connected to the refrigerant inlet of the first-stage condenser in the condensers with more than two stages through the non-condensable gas return pipeline to provide cooling capacity therefor.

3. The mixed gas multi-stage condensation device according to claim 2, characterized in that: The condenser with more than two stages is provided with three stages, including: A primary condenser (1) is used to perform a first condensation on the mixed gas to be treated to obtain a first liquid separated product and a mixed gas from which the first liquid separated product has been separated; A secondary condenser (2) is used to perform a second condensation on the mixed gas from which the first liquid separated product has been separated, to obtain a mixed gas of the second liquid separated product and the separated second liquid separated product; and a three-stage condenser (3) for performing a third condensation on the mixed gas from which the second liquid separated product has been separated, so as to obtain the final liquid separated product containing the non-condensable gas.

4. The mixed gas multi-stage condensation device according to claim 3, characterized in that: The mixed gas to be treated includes trichlorosilane, dichlorosilane, silicon tetrachloride and hydrogen, and the non-condensable gas is hydrogen.

5. The mixed gas multi-stage condensation device according to claim 3, characterized in that: The refrigerant of the secondary condenser (2) is ethylene glycol.

6. The mixed gas multi-stage condensation device according to claim 3, characterized in that: The refrigerant of the three-stage condenser (3) is Freon.

7. The mixed gas multi-stage condensation device according to claim 3, characterized in that: The temperature of the secondary condenser (2) is lower than the temperature of the primary condenser (1); and the temperature of the tertiary condenser (3) is lower than the temperature of the secondary condenser (2).

8. The mixed gas multi-stage condensation device according to claim 3, characterized in that: It also comprises a quenching tower (4), wherein the quenching tower (4) is used to quench the chlorosilane mixed gas generated by the reaction in the fluidized bed reactor to obtain the mixed gas to be treated.

9. The mixed gas multi-stage condensation device according to claim 3, characterized in that: The air inlet of the first-stage condenser (1) is used for the mixed gas to be treated to pass through, the air outlet of the first-stage condenser (1) is connected to the air inlet of the second-stage condenser (2), and the air outlet of the second-stage condenser (2) is connected to the air inlet of the third-stage condenser (3).

10. The mixed gas multi-stage condensation device according to claim 9, characterized in that: The liquid outlet of the primary condenser (1) and the liquid outlet of the secondary condenser (2) are both connected to the degassing storage tank (5).

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