A new type of silicon slurry cold hydrogenation reaction system
By using a silicon slurry cold hydrogenation reaction system, silicon powder is mixed with liquid silicon tetrachloride to form a slurry and pumped into a reactor. This solves the problems of wear, blockage and safety in the silicon powder transportation process, optimizes the polysilicon production process, improves equipment durability and safety, reduces costs and improves product gas quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SINOPEC NANJING ENG & CONSTR
- Filing Date
- 2025-06-09
- Publication Date
- 2026-05-29
AI Technical Summary
In current polysilicon production, there are problems such as equipment wear, pipeline blockage, high resource consumption, and safety hazards during silicon powder transportation, which affect production stability and safety.
A silicon slurry cold hydrogenation reaction system is adopted, in which silicon powder is mixed with liquid silicon tetrachloride to form a slurry, which is then pumped into a reactor. After being mixed with hydrogen and hydrogen chloride, the slurry reacts in the reactor. The traditional electric heater is eliminated, and a dust baffle and an electric heating device are installed to optimize the process design.
It solves the difficulties in silicon powder transportation, reduces resource consumption and production costs, improves equipment durability and safety, avoids plant shutdowns, and enhances product gas quality and energy utilization efficiency.
Smart Images
Figure CN224298911U_ABST
Abstract
Description
Technical Field
[0001] This utility model patent belongs to the field of polycrystalline silicon production and relates to a novel silicon slurry cold hydrogenation reaction system. Background Technology
[0002] Currently, polysilicon production mainly employs the modified Siemens process. This method consumes 19–24 tons of trichlorosilane (TCS) per ton of polysilicon produced, while also generating 15–20 tons of silicon tetrachloride (STC) as a byproduct. These byproducts react with air to form silicic acid and hydrogen chloride, severely polluting the environment and harming human health. The most effective method for recovering silicon tetrachloride is currently cold chlorination technology, which converts it back into trichlorosilane. This achieves a closed-loop circulation of materials within the plant, optimizes the process flow, and achieves zero emissions of pollutants.
[0003] Cold hydrogenation technology primarily utilizes a catalyst to generate trichlorosilane from silicon powder, hydrogen, and silicon tetrachloride in a fluidized bed reactor at temperatures ranging from 400℃ to 800℃ and pressures from 2 MPaG to 4 MPaG. The main reaction equation is as follows: Si + 2SiCl₄ + H₂ + HCl = 3SiHCl₃
[0004] However, existing cold hydrogenation systems use solid-state silicon powder as feedstock, which presents the following problems:
[0005] 1. During the silicon powder transportation process, silicon powder particles will cause a certain degree of wear to the pipelines and equipment, affecting the durability of the equipment and the stability of the system;
[0006] 2. Silica powder has the characteristic of easily clogging pipes. Therefore, when configuring pipes, it is necessary to use larger radius bends and slope designs.
[0007] 3. Silicon powder needs to undergo strict drying treatment before use. This process consumes a large amount of hydrogen resources and energy, which directly affects production costs and resource utilization efficiency.
[0008] 4. Silica powder has a certain explosion hazard, so its airtightness and explosion-proof measures must be fully considered during transportation to ensure production safety.
[0009] Therefore, it is necessary to develop a novel cold hydrogenation reaction system for silicon slurry in order to solve the above problems. Utility Model Content
[0010] The purpose of this utility model patent is to provide a novel silicon slurry cold hydrogenation reaction system and its preparation method, which solves the difficulties in silicon powder transportation during the trichlorosilane synthesis process and the problems of frequent failures caused by local overheating of traditional electric heaters leading to equipment shutdown.
[0011] The objective of this utility model can be achieved through the following technical solutions:
[0012] A novel cold hydrogenation reaction system for silicon slurry includes a hydrogenation reactor. The output end of a mixing discharge tank is connected to the top of the hydrogenation reactor via a raw material preheating system. The output end of the lower part of the hydrogenation reactor is connected in sequence to the raw material preheating system and a hydrogen preheater.
[0013] In the above system, the hydrogen output pipeline is connected to the top and middle of the hydrogenation reactor via a hydrogen preheater.
[0014] In the above system, an electric heating device is installed on the outer wall of the upper reaction zone of the cold hydrogenation reactor.
[0015] In the above system, the lower part of the cold hydrogenation reactor is equipped with a baffle plate.
[0016] In the above system, the hydrogen chloride output pipe is connected to the top of the cold hydrogenation reactor.
[0017] A method for realizing a novel cold hydrogenation reaction of silicon slurry using the above-described system, the method comprising the following steps:
[0018] (1) The silicon powder containing the catalyst and the liquid silicon tetrachloride are mixed into a slurry in a mixing tank to maintain the uniform suspension state of the slurry.
[0019] (2) The mixed slurry enters the raw material preheating system through the feed pump and undergoes multi-stage heat exchange with the high-temperature product gas produced by the cold hydrogenation reactor; at the same time, hydrogen from the compressor is mixed with hydrogen chloride after heat exchange with the product gas to obtain mixed gas 1; the preheated slurry enters from the nozzle at the top of the reactor, and the mixed gas 1 after heat exchange enters the reactor uniformly at an angle of 20-40°, vaporizes and reacts in the reaction zone 1-Ⅰ, and then hydrogen is introduced for the second time in the middle of the reactor to promote the reaction to move in the positive direction, accelerate the reaction rate and improve the conversion rate of reactants;
[0020] (3) The product gas exits the reactor from the top of the separation zone 1-II of the reactor, and after exchanging heat with the slurry and hydrogen, it enters the downstream distillation section for purification and reduction to produce polysilicon.
[0021] In the above preparation method, the catalyst mentioned in step (1) is copper chloride, and the content of the catalyst in the silicon powder is 0.1-1 wt%.
[0022] In the above preparation method, the flow rate ratio of hydrogen in mixed gas 1 and the second hydrogen introduced in step (2) is 3 to 5:1.
[0023] In the above preparation method, the molar ratio of silicon powder, liquid silicon tetrachloride, hydrogen gas and hydrogen chloride in step (2) is 1:1~3:0.5~1.5:0.5~1.5.
[0024] In the above preparation method, the reaction temperature in step (2) is 500-550℃ and the pressure is 2-3 MPaG.
[0025] In the above preparation method, the reason why the mixed gas 1 enters the reactor 1 uniformly at an angle of 20-40° is: 1. to guide the flow of materials; 2. to prevent solid materials in the reactor from entering the pipeline and causing material accumulation.
[0026] The beneficial effects of this utility model are:
[0027] The process technology for synthesizing trichlorosilane hydrogenation system, by changing the way silicon tetrachloride and silicon powder enter the reactor, optimizes the process and achieves the following beneficial effects:
[0028] (1) Trichlorosilane hydrogenation technology can be applied to silicon raw materials of various specifications without prior drying, thus reducing resource and energy consumption;
[0029] (2) Silicon powder slurry effectively solves the problem of wear and blockage of pipes and equipment caused by silicon powder particles, improves the durability of equipment and pipes, and reduces production costs;
[0030] (3) The silicon powder in the system is mixed with liquid silicon tetrachloride into a slurry, which avoids problems such as airtightness and explosion-proof measures during the silicon powder transportation process and improves production safety.
[0031] (4) The cold hydrogenation reactor is equipped with an electric heating device, thereby eliminating the traditional raw material electric heater, avoiding frequent failures due to local overheating that could lead to plant shutdown, and reducing equipment investment.
[0032] (5) After liquid silicon tetrachloride is mixed with raw silicon, it enters the reactor together with hydrogen. The reactants are evenly distributed and there is no need to set up a distributor.
[0033] (6) The optimized heat exchange network uses the reaction product gas to preheat the raw materials, thus making effective use of the system energy;
[0034] (7) A baffle is installed in the lower separation zone of the reactor to reduce the content of unreacted silicon powder in the product gas;
[0035] (8) The mixed slurry can be pumped into the reactor safely and easily. Attached Figure Description
[0036] Figure 1 This is a schematic diagram of the structure of this utility model patent.
[0037] The components include: 1. Hydrogenation reactor (I is the reaction zone, II is the separation zone); 2. Raw material preheating system; 3. Mixing discharge tank (including agitator); 4. Heating device; 5. Ash baffle; 6. Nozzle; 7. Hydrogen preheater; 8. Feed pump;
[0038] Logistics: 9. Slurry; 10. Waste residue; 11. Silicon powder; 12. Silicon tetrachloride; 13. Hydrogen chloride; 14. Hydrogen; 15. Product gas; 16. Primary hydrogen; 17. Secondary hydrogen. Detailed Implementation
[0039] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:
[0040] like Figure 1 A novel cold hydrogenation reaction system for silicon slurry includes a hydrogenation reactor 1. The output end of a mixing discharge tank is connected to the top of the hydrogenation reactor 1 via a raw material preheating system 2. The lower output end of the hydrogenation reactor 1 is sequentially connected to the raw material preheating system 2 and a hydrogen preheater 7. A hydrogen output pipe is connected to the top and middle of the hydrogenation reactor 1 via the hydrogen preheater 7. An electric heating device (4) is installed on the outer wall of the upper reaction zone of the cold hydrogenation reactor 1. A baffle plate 5 is installed at the bottom of the cold hydrogenation reactor 1. A hydrogen chloride output pipe is connected to the top of the cold hydrogenation reactor 1.
[0041] Example 1
[0042] Silicon powder containing 0.5 wt% copper chloride catalyst is mixed with liquid silicon tetrachloride in a mixing tank to form a slurry 9, maintaining the slurry in a uniform suspension state. The mixed slurry is fed into the raw material preheating system 2 via a feed pump 8, where it undergoes multi-stage heat exchange with the high-temperature product gas 15 produced by the cold hydrogenation reactor 1. Simultaneously, hydrogen gas 14 from the compressor exchanges heat with the product gas and then mixes with hydrogen chloride to obtain mixed gas 1. The preheated slurry enters from the top nozzle 6 of the reactor, and the heat-exchanged mixed gas 1 enters the reactor 1 uniformly at an angle of 20-40°, vaporizing and reacting in reaction zone 1-Ⅰ. Then, hydrogen gas is introduced a second time in the middle of the reactor to promote the reaction in the forward direction, accelerating the reaction rate and increasing the reactant conversion rate. The flow rate ratio of hydrogen gas in mixed gas 1 to the second introduced hydrogen gas is 4:1. The molar ratio of silicon powder, liquid silicon tetrachloride, hydrogen gas, and hydrogen chloride is 1:2:1:1. The reaction temperature in step (2) is 500-550℃ and the pressure is 2.5-2.8 MPaG.
[0043] The product gas exits the reactor from the top of the separation zone 1-II, exchanges heat with the slurry and hydrogen, and then enters the downstream distillation section for purification and reduction to produce polycrystalline silicon.
[0044] Product Specifications and Parameters Overview
[0045] product Content wt% Remark Trichlorosilane 70％～80％ main products silicon tetrachloride 10％～15％ Unreacted raw materials hydrogen chloride 5％～10％ byproducts hydrogen 1％～5％ It can be recycled through a recycling system Other chlorosilanes ≤1％ Byproducts such as dichlorosilane Total metallic impurities <1ppm Such as Fe, Al, Cr, etc.
[0046] By adopting the novel silicon slurry cold hydrogenation reaction system in this patent, the selectivity of trichlorosilane is improved, the concentration of by-products is reduced, the quality of product gas is further improved, and the energy consumption of subsequent separation is reduced.
Claims
1. A novel silicon slurry cold hydrogenation reaction system, characterized in that, The system includes a hydrogenation reactor (1), and the output end of the mixing discharge tank is connected to the top of the hydrogenation reactor (1) through the raw material preheating system (2); the output end of the lower part of the hydrogenation reactor (1) is connected in sequence to the raw material preheating system (2) and the hydrogen preheater (7).
2. The novel silicon slurry cold hydrogenation reaction system according to claim 1, characterized in that, The hydrogen output pipeline is connected to the top and middle of the hydrogenation reactor (1) via a hydrogen preheater (7).
3. The novel silicon slurry cold hydrogenation reaction system according to claim 1, characterized in that, An electric heating device (4) is provided on the outer wall of the upper reaction zone of the cold hydrogenation reactor (1).
4. The novel silicon slurry cold hydrogenation reaction system according to claim 1, characterized in that, The lower part of the cold hydrogenation reactor (1) is equipped with a dust baffle (5).
5. The novel silicon slurry cold hydrogenation reaction system according to claim 1, characterized in that, The hydrogen chloride output pipe is connected to the top of the cold hydrogenation reactor (1).