Gas phase washing system of hydrochlorination synthesis furnace

Abstract

The utility model discloses a hydrochlorination synthesis furnace gas phase washing system which comprises a hydrochlorination synthesis furnace, a heat exchanger, a first-stage leaching tower and a second-stage leaching tower which are communicated in sequence, and further comprises a slurry recycling pool, a chlorosilane storage tank and a circulating pump. According to the utility model, a gas phase discharged from a hydrochlorination synthesis process enters the two-stage leaching tower to be washed, silicon powder, a catalyst, high-boiling residues and other impurities in the gas phase are removed through chlorosilane leaching, so that the impurities can be more thoroughly washed and removed, the purity of the gas phase is improved, the product quality is ensured, the gas phase entering the two-stage leaching tower contains less impurities, and the product quality is improved. And the packing layer is not easy to block, and the service life is long.

Description

Technical field:

[0001] The utility model belongs to the technical field of polysilicon production, and in particular relates to a gas phase washing system for a hydrochlorination synthesis furnace. Background technology:

[0002] In the polysilicon production process, the hydrochlorination technology successfully converts silicon tetrachloride, hydrogen chloride, and dichlorosilane, which are by-products in the polysilicon production process, into trichlorosilane, realizing a closed cycle of polysilicon production and avoiding pollutant emissions. It is an ideal production technology. At present, a leaching packing tower is usually connected to the gas phase outlet of the hydrochlorination synthesis furnace, and liquid chlorosilane is used to elute impurities such as silicon powder, catalysts, and high boiling points in the gas phase of the hydrochlorination synthesis furnace. The leached gas phase enters the subsequent condensation process. However, in actual operation, the above impurities have the problem of insufficient elution. Some impurities will adhere to the packing and block the gaps of the wire mesh packing during the mass and heat transfer between the gas phase and the liquid chlorosilane on the packing, causing pitting and erosion of the stainless steel packing, affecting the normal operation of the system and short service life; and the gas phase impurity removal effect is general, and the gas phase entering the condensation process still contains a small amount of impurities, affecting the quality of the final product. Utility model content:

[0003] The utility model aims to provide a gas phase washing system for a hydrochlorination synthesis furnace to solve the problems mentioned in the background technology.

[0004] The utility model is implemented by the following technical solutions:

[0005] A gas phase washing system for a hydrochlorination synthesis furnace comprises a hydrochlorination synthesis furnace, and also comprises a heat exchanger, a primary elution tower, a secondary elution tower, and a circulation pump; the gas phase outlet of the hydrochlorination synthesis furnace is communicated with the heat medium inlet of the heat exchanger, the heat medium outlet of the heat exchanger is communicated with the gas phase inlet of the primary elution tower, the gas phase outlet of the primary elution tower is communicated with the gas phase inlet of the secondary elution tower; the discharge port of the secondary elution tower is communicated with the liquid inlet of the circulation pump, and the liquid outlet of the circulation pump is respectively communicated with the liquid inlet of the primary elution device of the primary elution tower and the liquid inlet of the secondary elution device of the secondary elution tower. The gas phase of the chlorination hydrogenation synthesis furnace passes through the heat exchanger, and the heat can be recovered to other sections. The gas phase after cooling enters the first-level washing tower from the gas phase inlet of the first-level washing tower, passes through the chlorosilane liquid seal and the first-level washing device for washing, and after preliminarily removing impurities such as silicon powder, catalyst, and high boiling point in the gas phase, the gas phase is discharged from the gas phase outlet of the first-level washing tower, and then enters the second-level washing tower through the gas phase inlet of the second-level washing tower, passes through the chlorosilane liquid seal and the second-level washing device for washing, and after further dust removal and cooling, the gas phase basically does not contain impurities such as silicon powder, catalyst, and high boiling point, and the gas phase is discharged from the gas phase outlet of the second-level washing tower and enters the subsequent condensation process to separate chlorosilane and hydrogen. Since the primary elution tower has carried out preliminary dust removal on the gas phase, the chlorosilane liquid in the secondary elution tower contains fewer impurities. The chlorosilane liquid at the bottom of the secondary elution tower is sent to the secondary elution device and the primary elution device respectively through the circulation pump to be recycled as spray liquid without affecting the normal operation of the circulation pump and the cleanliness of the gas phase.

[0006] Furthermore, the liquid outlet of the primary elution tower is connected to a slurry recovery pool. After the system has been running for a period of time, the chlorosilane liquid at the bottom of the primary elution tower contains a lot of impurities, and the residual liquid carrying impurities such as silicon powder, catalyst and high boiling products in the tower is discharged from the liquid outlet of the primary elution tower to the slurry recovery pool, and subsequent processes such as chlorosilane recovery and hydrolysis post-processing of impurities can be carried out.

[0007] Furthermore, the first-level elution device includes a first-level spray pipe, which passes through the tower body of the first-level elution tower and extends to the interior of the first-level elution tower, and the liquid inlet of the first-level spray pipe is connected to the liquid outlet of the circulation pump; a plurality of first-level spray heads are connected to the bottom of the first-level spray pipe, and the first-level spray heads are higher than the gas phase inlet of the first-level elution tower.

[0008] Furthermore, the secondary elution device includes an upper spray pipe and a lower spray pipe from top to bottom, both of which pass through the tower body of the secondary elution tower and extend to the inside of the secondary elution tower, and the liquid inlet of the upper spray pipe and the liquid inlet of the lower spray pipe are both connected to the liquid outlet of the circulation pump; the bottom of the upper spray pipe is connected to a plurality of upper spray heads, and the bottom of the lower spray pipe is connected to a plurality of lower spray heads, and the lower spray heads are higher than the gas phase inlet of the secondary elution tower; a packing layer is arranged between the upper spray pipe and the lower spray pipe, and the packing layer is fixedly connected to the inner wall of the secondary elution tower. This arrangement allows the gas phase entering the secondary elution tower to pass through the chlorosilane liquid seal and the spray of the lower spray head in turn, and the impurities in the gas phase are basically removed, and then pass through the packing layer and the upper spray head, which can remove impurities to the greatest extent and is not easy to clog the packing.

[0009] Furthermore, a liquid replenishing port is provided at the bottom of the secondary elution tower, and the liquid replenishing port is connected to a chlorosilane storage tank. After running for a period of time, the chlorosilane liquid contains more impurities, and after the chlorosilane liquid at the bottom of the primary elution tower is discharged, new chlorosilane liquid needs to be replenished.

[0010] Advantages of the utility model:

[0011] The utility model provides a gas phase washing system for a hydrochlorination synthesis furnace, which passes the gas phase discharged from the hydrochlorination synthesis process into a two-stage leaching tower for washing, and removes impurities such as silicon powder, catalyst and high boiling point in the gas phase by leaching with chlorosilane. The two-stage leaching tower is set up, the first-stage leaching tower is used for preliminary impurity removal, and the second-stage leaching tower is used for deep impurity removal. On the one hand, it can wash and remove impurities more thoroughly, which is conducive to improving the purity of the gas phase and ensuring the quality of the product; on the other hand, the gas phase entering the second-stage leaching tower contains fewer impurities, the packing layer is not prone to clogging, etc., and the service life is long. In addition, the chlorosilane liquid in the second-stage leaching tower is used as a spray liquid for recycling, which does not affect the normal operation of the system and saves resources. Description of the drawings:

[0012] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 This is a schematic diagram of a gas phase washing system for a hydrochlorination synthesis furnace in Example 1.

[0014] The accompanying drawings are as follows:

[0015] 1. Chlorine hydrogenation synthesis furnace; 2. Heat exchanger; 3. Primary elution tower; 31. Primary spray pipe; 32. Primary spray head; 4. Slurry recovery tank; 5. Secondary elution tower; 51. Upper spray pipe; 52. Upper spray head; 53. Packing layer; 54. Lower spray pipe; 55. Lower spray head; 6. Chlorosilane storage tank; 7. Circulation pump. Specific implementation method:

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] Example 1

[0018] A gas phase washing system for a hydrochlorination synthesis furnace, such as Figure 1 As shown, it includes a hydrochlorination synthesis furnace 1, a heat exchanger 2, a primary elution tower 3, a secondary elution tower 5, and a circulation pump 7. The gas phase outlet of the hydrochlorination synthesis furnace 1 is communicated with the heat medium inlet of the heat exchanger 2, the heat medium outlet of the heat exchanger 2 is communicated with the gas phase inlet of the primary elution tower 3, and the gas phase outlet of the primary elution tower 3 is communicated with the gas phase inlet of the secondary elution tower 5. The discharge port of the secondary elution tower 5 is communicated with the liquid inlet of the circulation pump 7, and the liquid outlet of the circulation pump 7 is communicated with the liquid inlet of the primary elution device of the primary elution tower 3 and the liquid inlet of the secondary elution device of the secondary elution tower 5, respectively.

[0019] The primary elution device includes a primary spray pipe 31, which passes through the tower body of the primary elution tower 3 and extends to the inside of the primary elution tower 3. The liquid inlet of the primary spray pipe 31 is connected to the liquid outlet of the circulation pump 7. The bottom of the primary spray pipe 31 is connected to a plurality of primary spray heads 32, which are higher than the gas phase inlet of the primary elution tower 3. The liquid outlet of the primary elution tower 3 is connected to a slurry recovery tank 4.

[0020] The secondary elution device includes an upper spray pipe 51 and a lower spray pipe 54 from top to bottom. Both the upper spray pipe 51 and the lower spray pipe 54 pass through the tower body of the secondary elution tower 5 and extend to the inside of the secondary elution tower 5. The liquid inlet of the upper spray pipe 51 and the liquid inlet of the lower spray pipe 54 are both connected to the liquid outlet of the circulation pump 7. The bottom of the upper spray pipe 51 is connected to a plurality of upper spray heads 52, and the bottom of the lower spray pipe 54 is connected to a plurality of lower spray heads 55, which are higher than the gas phase inlet of the secondary elution tower 5. A packing layer 53 is arranged between the upper spray pipe 51 and the lower spray pipe 54, and the packing layer 53 is fixedly connected to the inner wall of the secondary elution tower 5. A liquid replenishing port is provided at the lower part of the secondary elution tower 5, and the liquid replenishing port is connected to the chlorosilane storage tank 6.

[0021] The working process is as follows:

[0022] After the gas phase of the chlorine hydrogenation synthesis furnace 1 is cooled by the heat exchanger 2, it enters the primary washing tower 3 from the gas phase inlet of the primary washing tower 3, passes through the chlorosilane liquid seal and the primary spray head 32 for washing, and after the impurities such as silicon powder, catalyst, and high boiling point in the gas phase are preliminarily removed, the gas phase is discharged from the gas phase outlet of the primary washing tower 3, and then enters the secondary washing tower 5 through the gas phase inlet of the secondary washing tower 5. The gas phase passes through the chlorosilane liquid seal and the lower spray head 55 for spraying, and the impurities in the gas phase are basically removed. After passing through the packing layer 53 and the upper spray head 52, the gas phase is further dusted and cooled, and the gas phase basically does not contain impurities such as silicon powder, catalyst, and high boiling point. The gas phase is discharged from the gas phase outlet of the secondary washing tower 5 and enters the subsequent condensation process to separate the chlorosilane and hydrogen. Since the primary leaching tower 3 has carried out preliminary dust removal on the gas phase, the chlorosilane liquid in the secondary leaching tower 5 contains fewer impurities. The chlorosilane liquid at the bottom of the secondary leaching tower 5 is sent to the secondary leaching device and the primary leaching device respectively through the circulating pump 7, and is recycled as a spray liquid, and does not affect the normal operation of the circulating pump 7 and the cleanliness of the gas phase. After the system has been running for a period of time, the chlorosilane liquid at the bottom of the primary leaching tower 3 contains more impurities. As the residual liquid carrying impurities such as silicon powder, catalyst and high boiling products in the tower is discharged from the liquid outlet of the primary leaching tower 3 to the slurry recovery tank 4, the subsequent processes such as chlorosilane recovery and hydrolysis post-processing impurities can be carried out. After running for a period of time, the chlorosilane liquid contains more impurities. After the chlorosilane liquid at the bottom of the primary leaching tower 3 is discharged, new chlorosilane liquid needs to be supplemented.

[0023] Example 2

[0024] A gas phase scrubbing system for a chlorination hydrogenation synthesis furnace is the same as that of Example 1 as a whole, except that it further includes a controller; a liquid level meter, a turbidity meter, and a colorimeter are arranged at the lower parts of a primary elution tower 3 and a secondary elution tower 5, and the liquid level meter, the turbidity meter, and the colorimeter are all connected to the signal input end of the controller; a flow valve is arranged on the connecting pipe between a circulation pump 7 and a primary spray pipe 31, on the connecting pipe between the circulation pump 7 and an upper spray pipe 51, on the connecting pipe between the circulation pump 7 and a lower spray pipe 54, on the connecting pipe between the liquid outlet of the primary elution tower 3 and a slurry recovery tank 4, and on the connecting pipe between the liquid replenishment port of the secondary elution tower 5 and a chlorosilane storage tank 6, and the flow valve is connected to the signal output end of the controller.

[0025] During operation, the opening and closing size of each flow valve can be controlled according to the liquid level, impurity content, etc. of the chlorosilane at the bottom of the primary elution tower 3 and the secondary elution tower 5, so that the system can operate more energy-efficiently and stably.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A gas phase scrubbing system for a hydrochlorination synthesis furnace, comprising a hydrochlorination synthesis furnace, characterized in that: It also includes a heat exchanger, a primary elution tower, a secondary elution tower, and a circulation pump; the gas phase outlet of the hydrochlorination synthesis furnace is communicated with the heat medium inlet of the heat exchanger, the heat medium outlet of the heat exchanger is communicated with the gas phase inlet of the primary elution tower, and the gas phase outlet of the primary elution tower is communicated with the gas phase inlet of the secondary elution tower; the discharge port of the secondary elution tower is communicated with the liquid inlet of the circulation pump, and the liquid outlet of the circulation pump is respectively communicated with the liquid inlet of the primary elution device of the primary elution tower and the liquid inlet of the secondary elution device of the secondary elution tower.

2. A gas phase scrubbing system for a hydrochlorination synthesis furnace according to claim 1, characterized in that: The liquid outlet of the primary elution tower is connected to a slurry recovery tank.

3. A gas phase scrubbing system for a hydrochlorination synthesis furnace according to claim 1 or 2, characterized in that: The primary elution device includes a primary spray pipe, which passes through the tower body of the primary elution tower and extends to the interior of the primary elution tower, and the liquid inlet of the primary spray pipe is connected to the liquid outlet of the circulation pump; a plurality of primary spray heads are connected to the bottom of the primary spray pipe, and the primary spray heads are higher than the gas phase inlet of the primary elution tower.

4. A gas phase scrubbing system for a hydrochlorination synthesis furnace according to claim 1, characterized in that: The secondary elution device comprises an upper spray pipe and a lower spray pipe from top to bottom, both of which pass through the tower body of the secondary elution tower and extend to the inside of the secondary elution tower, and the liquid inlet of the upper spray pipe and the liquid inlet of the lower spray pipe are both connected to the liquid outlet of the circulation pump; a plurality of upper spray heads are connected to the bottom of the upper spray pipe, and a plurality of lower spray heads are connected to the bottom of the lower spray pipe, and the lower spray heads are higher than the gas phase inlet of the secondary elution tower; a packing layer is arranged between the upper spray pipe and the lower spray pipe, and the packing layer is fixedly connected to the inner wall of the secondary elution tower.

5. A gas phase scrubbing system for a hydrochlorination synthesis furnace according to claim 1 or 4, characterized in that: A liquid replenishing port is provided at the lower part of the secondary elution tower, and the liquid replenishing port is connected to a chlorosilane storage tank.

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