Amorphous silicon powder treatment system in electronic grade polysilicon tail gas

Abstract

The present invention discloses a system for treating amorphous silicon powder in electronic-grade polysilicon tail gas, relating to the technical field of polysilicon production. Its main purpose is to remove amorphous silicon powder from reduced tail gas and reduce the failure rate of tail gas recovery unit equipment. The main technical solution of the present invention is as follows: a system for treating amorphous silicon powder in electronic-grade polysilicon tail gas, comprising: the upper end of a tower body connected to an exhaust pipe, and the lower end of the tower body connected to a filter; the separation section comprising a spray mechanism and a cyclone separation mechanism, the spray mechanism and the cyclone separation mechanism being sequentially arranged from top to bottom within the tower body; the spray mechanism comprising a spray structure and a packing structure sequentially arranged from top to bottom; the tangential inlet pipe of the cyclone separation mechanism penetrating the side wall of the tower body; and the upper outlet of the cyclone separation mechanism being provided with a cover to prevent spray liquid from entering the cyclone separation mechanism through the upper outlet.

Description

Technical Field

[0001] The present invention relates to the technical field of polysilicon production, in particular to a system for processing amorphous silicon powder in electronic-grade polysilicon tail gas. Background Art

[0002] At present, electronic-grade polysilicon is mainly produced using the modified Siemens method. Due to factors such as the reduction furnace ratio, current and temperature differences at different stages, the recovered gaseous chlorosilane contains a large amount of amorphous silicon powder. SiHCl3 and hydrogen react in the reduction furnace through chemical vapor deposition to produce polysilicon. The specific reaction equation is: 3SiHCl3+H2→2Si+5HCl+SiCl4. During the chemical vapor deposition process, gaseous chlorosilane, hydrogen and a large amount of amorphous silicon powder are produced. During the recovery of gaseous chlorosilane and hydrogen, amorphous silicon powder can easily cause wear of the exhaust gas recovery condensation equipment, leading to leakage, equipment blockage and a short replacement cycle of compressor wearing parts in the compressor system. Summary of the Invention

[0003] In view of this, the present invention provides a system for treating amorphous silicon powder in electronic-grade polysilicon tail gas, the main purpose of which is to remove amorphous silicon powder in the reduction tail gas and reduce the failure rate of the tail gas recovery unit equipment.

[0004] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0005] The present invention provides a system for processing amorphous silicon powder in electronic-grade polysilicon tail gas, the system comprising: a tower body and a separation part;

[0006] The upper end of the tower body is connected to the exhaust pipe, and the lower end of the tower body is connected to the filter;

[0007] The separation part includes a spray mechanism and a cyclone separation mechanism, which are arranged in sequence from top to bottom inside the tower body. The spray mechanism includes a spray structure and a filler structure arranged in sequence from top to bottom. The tangential inlet pipe of the cyclone separation mechanism passes through the side wall of the tower body. The upper end outlet of the cyclone separation mechanism is provided with a cover body to prevent the spray liquid from entering the cyclone separation mechanism through the upper end outlet.

[0008] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0009] Optionally, the cover body is a spherical cover body, and the edge of the spherical cover body is fixedly connected to the edge of the upper end outlet through a plurality of support rods.

[0010] Optionally, the spray structure includes an infusion pipe and a plurality of spray pipes connected to the lower side wall of the infusion pipe.

[0011] Optionally, the filler structure includes a support plate, a filler and a pressing plate arranged in sequence from bottom to top, the upper surface of the support plate is evenly distributed with a plurality of support tubes, the tube walls of the support tubes are evenly distributed with a plurality of air holes, the upper surface of the pressing plate is arranged with a plurality of overflow grooves, and the plurality of overflow grooves and the plurality of spray pipes are staggered with each other.

[0012] Optionally, the lower end of the tower body is connected to the inlet end of the filter, and the outlet end of the filter is connected to the distillation unit and the liquid infusion pipe.

[0013] Optionally, the filter includes a first filter and a second filter connected in parallel, the outlet end of the first filter and the outlet end of the second filter are respectively connected to the backwash pipe, and the slag discharge port of the filter is connected to the slurry unit.

[0014] Optionally, the filter is provided with a differential pressure sensor.

[0015] By means of the above technical solution, the present invention has at least the following advantages:

[0016] The exhaust gas from the reduction furnace containing amorphous silicon powder enters the cyclone separation mechanism through the tangential inlet pipe. The heavy components and silicon powder with larger particle size spirally settle in the shell of the cyclone separation mechanism, and the light components and silicon powder with smaller particle size are discharged from the upper outlet along with the exhaust gas, pass over the edge of the cover, and rise upward.

[0017] At the same time, the spray structure sprays out spray liquid, and the spray liquid and tail gas contact in countercurrent in the packing structure, and the silicon powder with smaller particle size is washed away. The cleaned reduction furnace tail gas enters the tail gas recovery unit through the exhaust pipe.

[0018] At the same time, since the cover covers the upper outlet of the cyclone separation mechanism, the downward-flowing spray liquid is prevented from entering the cyclone separation mechanism from the upper outlet, and the spiral airflow in the cyclone separation mechanism will not be affected by the spray liquid, thereby ensuring that silicon powder with larger particle size can be successfully separated in the cyclone separation mechanism.

[0019] After the above treatment process, the probability of silicon powder wearing out the condensing equipment is reduced, leakage is avoided, and silicon powder is prevented from clogging the equipment, which extends the replacement cycle of the compressor wearing parts and reduces the failure rate of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic structural diagram of a system for processing amorphous silicon powder in electronic-grade polysilicon tail gas provided by an embodiment of the present invention;

[0021] Figure 2 for Figure 1 Enlarged view of part A;

[0022] Figure 3 A top view of the pressing plate.

[0023] The figure marks in the drawings of the specification include: tower body 1, exhaust pipe 2, cyclone separation mechanism 3, cover body 4, support rod 5, liquid infusion pipe 6, spray pipe 7, support plate 8, pressing plate 9, support pipe 10, air vent 11, overflow trough 12, first filter 13, second filter 14, backwash pipe 15, output pipe 16, distillation main pipe 17, slag discharge port 18, and differential pressure sensor 19. DETAILED DESCRIPTION

[0024] To further illustrate the technical means and effects employed by the present invention to achieve its intended objectives, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 As shown, an embodiment of the present invention provides a system for processing amorphous silicon powder in electronic-grade polysilicon tail gas, which includes: a tower body 1 and a separation part;

[0027] The upper end of the tower body 1 is connected to the exhaust pipe 2, and the lower end of the tower body 1 is connected to the filter;

[0028] The separation part includes a spray mechanism and a cyclone separation mechanism 3, which are arranged in sequence from top to bottom inside the tower body 1. The spray mechanism includes a spray structure and a filler structure arranged in sequence from top to bottom. The tangential inlet pipe of the cyclone separation mechanism 3 passes through the side wall of the tower body 1, and the upper end outlet of the cyclone separation mechanism 3 is provided with a cover body 4 for preventing the spray liquid from entering the cyclone separation mechanism 3 through the upper end outlet.

[0029] The working process of a system for treating amorphous silicon powder in electronic-grade polysilicon tail gas is as follows:

[0030] The reduction furnace tail gas containing amorphous silicon powder enters the cyclone separation mechanism 3 through the tangential inlet pipe. The heavy component and the silicon powder with larger particle size spirally settle in the shell of the cyclone separation mechanism 3, and the light component and the silicon powder with smaller particle size are discharged from the upper end outlet along with the tail gas, and pass over the edge of the cover body 4 and rise upward.

[0031] At the same time, the spray structure sprays out spray liquid, and the spray liquid and tail gas contact in countercurrent in the packing structure, and the silicon powder with smaller particle size is washed away. The cleaned reduction furnace tail gas enters the tail gas recovery unit through the exhaust pipe 2.

[0032] At the same time, since the cover body 4 covers the upper outlet of the cyclone separation mechanism 3, the downward-flowing spray liquid is prevented from entering the cyclone separation mechanism 3 from the upper outlet, and the spiral airflow in the cyclone separation mechanism 3 will not be affected by the spray liquid, thereby ensuring that silicon powder with larger particle size can be successfully separated in the cyclone separation mechanism 3.

[0033] After the above treatment process, the probability of silicon powder in the exhaust gas wearing out the exhaust gas recovery unit condensing equipment is reduced, leakage is avoided, and silicon powder is prevented from clogging the equipment, which extends the replacement cycle of the compressor wearing parts and reduces the failure rate of the equipment.

[0034] Specifically, the spray liquid is chlorosilane liquid.

[0035] Specifically, the cyclone separation mechanism 3 and the spray mechanism cooperate with each other to efficiently remove amorphous silicon powder in the tail gas.

[0036] In a specific embodiment, the cover body 4 is a spherical cover body 4 , and the edge of the spherical cover body 4 is fixedly connected to the edge of the upper outlet through a plurality of support rods 5 .

[0037] In this embodiment, specifically, the spray liquid is eluted onto the spherical cover body 4, flows along the curved surface of the spherical cover body 4 toward the edge of the cover body 4, and finally settles to the bottom of the tower body 1; at the same time, there is a gap between adjacent support rods 5, and the tail gas that removes larger particles of silicon powder passes through the gap and then passes over the spherical cover body 4 and rises upward, and the gas-solid separation process and the downward flow of the spray liquid do not interfere with each other.

[0038] like Figure 1 As shown, in a specific embodiment, the spray structure includes a liquid infusion tube 6 and a plurality of spray tubes 7 connected to the lower side wall of the liquid infusion tube 6.

[0039] In this embodiment, specifically, the liquid infusion pipe 6 is horizontally arranged above the interior of the tower body 1, and the inlet end of the liquid infusion pipe 6 passes through the side wall of the tower body 1, which is used to drain the external spray liquid into the tower body 1 and spray it to the packing structure through the spray pipe 7.

[0040] like Figures 1 to 3 As shown, in a specific embodiment, the filler structure includes a support plate 8, a filler and a pressing plate 9 arranged in sequence from bottom to top, the upper surface of the support plate 8 is evenly distributed with a plurality of support tubes 10, the tube walls of the support tubes 10 are evenly distributed with a plurality of air holes 11, and the upper surface of the pressing plate 9 is arranged with a plurality of overflow grooves 12, and the plurality of overflow grooves 12 and the plurality of spray pipes 7 are staggered with each other.

[0041] In this embodiment, the packing is a rectangular saddle ring, 80*40*0.5 (outer diameter*height*thickness mm), with a stacking number of 5800 / m 3 , bulk density 148kg / m3 , specific surface area 74.9m2 / m 3 , porosity 0.96.

[0042] In this embodiment, a plurality of first mounting ports are provided on the surface of the support plate 8, the lower end of the support tube 10 is welded to the first mounting port, a plurality of second mounting ports are provided on the surface of the pressing plate 9, and the lower end of the overflow groove 12 is welded to the second mounting port; the spray liquid sprayed from the spray pipe 7 is first deposited above the pressing plate 9, and when the liquid level of the spray liquid rises to the upper end of the overflow groove 12, the spray liquid passes through the second mounting port and contacts the filler.

[0043] At the same time, compared with the case where multiple air holes 11 are directly provided on the support plate 8 , the tube wall of the support tube 10 is evenly distributed with multiple air holes 11 , and the filler structure can be provided with more air holes 11 .

[0044] Specifically, the diameter of the support tube 10 gradually decreases from top to bottom, so that the tube wall of the support tube 10 can share a part of the weight of the stacked filler.

[0045] Through the above structure, the spray liquid first contacts the pressing plate 9 and then overflows the upper end of the overflow trough 12, consuming the kinetic energy of the spray liquid just leaving the spray pipe 7, avoiding the spray liquid from violently impacting the filler and destroying the stacking structure of the filler.

[0046] like Figure 1 As shown, in a specific embodiment, the lower end of the tower body 1 is connected to the inlet end of the filter, and the outlet end of the filter is connected to the distillation unit and the liquid infusion pipe 6.

[0047] In this embodiment, specifically, the silicon powder is intercepted by the filtering action of the filter, producing a relatively clean chlorosilane liquid component. A portion of the chlorosilane liquid enters the distillation unit for multi-stage distillation, thereby reducing the difficulty of the distillation process; the other portion of the chlorosilane liquid component reaches the liquid infusion pipe 6 and is again used as a spray liquid to wash the reduction furnace exhaust.

[0048] like Figure 1 As shown, in a specific embodiment, the filter includes a first filter 13 and a second filter 14 connected in parallel, the outlet end of the first filter 13 and the outlet end of the second filter 14 are respectively connected to the backwash pipe 15, and the slag discharge port 18 of the filter is connected to the slurry unit.

[0049] In this embodiment, specifically, the upper head of the first filter 13 and the upper head of the second filter 14 are respectively connected to one end of the backwash pipe 15 and one end of the output pipe 16, and the other end of the backwash pipe 15 and the other end of the output pipe 16 are connected to the distillation main pipe 17.

[0050] When the pressure difference of the first filter 13 is large, the operator can switch the first filter 13 to the second filter 14, and then open the slag discharge port 18 valve and the backwash pipe 15 valve of the first filter 13 to flush and discharge the silicon powder in the first filter 13 into the slurry unit. The slurry unit heats the chlorosilane in the backwash liquid through a spiral dryer to recover it, and also safely and environmentally recovers the amorphous silicon powder in the backwash liquid, so that the filter element of the first filter 13 is restored to cleanliness and the switched first filter 13 is in standby state.

[0051] like Figure 1 As shown, in a specific embodiment, the filter is provided with a differential pressure sensor 19 .

[0052] In this embodiment, specifically, the pressure difference sensor 19 is integrated into the DCS control system, which makes it convenient for the operator to remotely control the filter pressure difference and backwash time, control the filter inlet valve, outlet valve, and slag discharge port 18 valve, and circulate backwash and put the filter into use.

[0053] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A system for processing amorphous silicon powder in electronic grade polysilicon tail gas, characterized in that: include: a tower body, wherein the upper end of the tower body is connected to the exhaust pipe, and the lower end of the tower body is connected to the filter; a separation portion, the separation portion comprising a spray mechanism and a cyclone separation mechanism, the spray mechanism and the cyclone separation mechanism being sequentially arranged from top to bottom within the tower body, the spray mechanism comprising a spray structure and a packing structure sequentially arranged from top to bottom, the tangential inlet pipe of the cyclone separation mechanism penetrating the side wall of the tower body, and the upper end outlet of the cyclone separation mechanism being provided with a cover body for preventing spray liquid from entering the cyclone separation mechanism through the upper end outlet; The cover body is a spherical cover body, and the edge of the spherical cover body is fixedly connected to the edge of the upper end outlet through a plurality of support rods; The spray structure includes a liquid infusion pipe and a plurality of spray pipes connected to the lower side wall of the liquid infusion pipe.

2. The system for processing amorphous silicon powder in electronic-grade polysilicon tail gas according to claim 1, characterized in that: The packing structure includes a support plate, a packing and a pressing plate arranged in sequence from bottom to top, the upper surface of the support plate is evenly distributed with a plurality of support tubes, the tube walls of the support tubes are evenly distributed with a plurality of air holes, the upper surface of the pressing plate is arranged with a plurality of overflow grooves, and the plurality of overflow grooves and the plurality of spray pipes are staggered with each other.

3. The system for processing amorphous silicon powder in electronic-grade polysilicon tail gas according to claim 1, characterized in that: The lower end of the tower body is connected to the inlet end of the filter, and the outlet end of the filter is connected to the distillation unit and the liquid infusion pipe.

4. The system for processing amorphous silicon powder in electronic-grade polysilicon tail gas according to claim 3, characterized in that: The filter includes a first filter and a second filter connected in parallel, the outlet end of the first filter and the outlet end of the second filter are respectively connected to the backwash pipe, and the slag discharge port of the filter is connected to the slurry unit.

5. The system for processing amorphous silicon powder in electronic-grade polysilicon tail gas according to claim 3, characterized in that: The filter is provided with a differential pressure sensor.

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