A cold hydrogenation heat recovery system
By employing a combined system of mixers, multiphase flow heat exchangers, and high-efficiency heat exchangers in the cold hydrogenation process, the problem of low heat utilization rate was solved, efficient heat recovery was achieved, and production costs were reduced.
Patent Information
- Application Number
- CN202521835213.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-08-27
AI Technical Summary
In existing technologies, the preheating method for silicon tetrachloride and hydrogen in the cold hydrogenation process results in low heat utilization, heat waste, and increased production costs.
A combined system of mixer, multiphase flow heat exchanger, high-efficiency heat exchanger and vaporizer is adopted to improve heat utilization efficiency and reduce the consumption of steam and circulating water through multiple heat exchanges.
This improved heat utilization, reduced the amount of steam required for heating the mixture of hydrogen and silicon tetrachloride, and reduced the amount of cooling water used in the gas phase at the outlet of the scrubbing tower, thus saving resources and reducing production costs.
Smart Images
Figure CN224681325U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of polycrystalline silicon production technology, specifically to a cold hydrogenation heat recovery system. Background Technology
[0002] Currently, the technology used in my country to produce polysilicon is primarily the modified Siemens process. Polysilicon produced using this technology accounts for over 80% of the country's total output. A crucial step in the modified Siemens process is cold hydrogenation. Cold hydrogenation involves mixing and heating hydrogen and silicon tetrachloride, then subjecting them to an endothermic reaction with silicon powder in a fluidized bed reactor at 530℃-560℃ and 2.5MPa-3.0MPa. Prior to the cold hydrogenation reaction, both silicon tetrachloride and hydrogen need to be preheated by gradually increasing the temperature.
[0003] In existing technologies, the common industry practice is to separately heat silicon tetrachloride and hydrogen to 100℃-120℃ using the gaseous material at the outlet of the scrubbing tower, then mix them before entering the vaporizer, where they are heated to 120℃-140℃ with steam, and then further heated to 160℃ with steam in the superheater, followed by further heating. This preheating method, which involves heating, mixing, and then heating again, results in the gaseous temperature at the scrubbing tower outlet dropping to a maximum of 120℃, leading to low heat utilization. The 120℃ gaseous temperature cannot be reused and must be cooled directly using circulating water or an air cooler. This inefficient use of heat results in heat waste and requires more cooling energy, increasing production costs. Utility Model Content
[0004] The purpose of this invention is to develop a cold hydrogenation heat recovery system that reduces the steam required for preheating hydrogen and silicon tetrachloride and the cooling water required for cooling the gas phase at the outlet of the scrubbing tower.
[0005] This utility model is achieved through the following technical solution:
[0006] A cold hydrogenation heat recovery system, comprising:
[0007] A mixer is used to mix silicon tetrachloride and hydrogen.
[0008] The mixer outlet is sequentially connected to a multiphase flow heat exchanger, a high-efficiency heat exchanger, a vaporizer, and a superheater. The heat exchange chamber of the high-efficiency heat exchanger is connected to the heat exchange chamber of the multiphase flow heat exchanger. The gas phase from the scrubbing tower outlet is sequentially fed into the high-efficiency heat exchanger and the multiphase flow heat exchanger.
[0009] Optionally, the high-efficiency heat exchanger includes a shell, with tube sheets at both ends inside the shell, and multiple heat exchange tubes arranged in a spiral trajectory between the two tube sheets. An inlet pipe and an outlet pipe are connected to the shell between the two tube sheets.
[0010] Optionally, the housing is provided with an inlet end cap and an outlet end cap at both ends, and the two tube sheets are respectively disposed in the inlet end cap and the outlet end cap.
[0011] Optionally, a central cylinder is provided between the two tube sheets in the middle of the shell, and a plurality of heat exchange tubes are wound around the outside of the central cylinder.
[0012] Optionally, the two ends of the central cylinder near the tube sheet are reduced diameter sections, and the bending radius of the heat exchange tubes in the reduced diameter sections of the central cylinder is 10D-15D.
[0013] Optionally, multiple heat exchange tubes are wound sequentially around the outside of the central cylinder in a multi-layer structure, with adjacent layers of heat exchange tubes wound in opposite directions.
[0014] Optionally, the gap between the heat exchange tubes is 1mm-2mm, and the gap between layers is 1mm-1.5mm.
[0015] Optionally, the heat exchange tube has a helix angle of 15°, a diameter of φ19-φ25, and a center distance of 25mm-28mm.
[0016] The beneficial effects of this utility model are:
[0017] This invention utilizes the heat of the gas phase at the outlet of the scrubbing tower, thereby reducing the amount of steam required for heating the mixture of hydrogen and silicon tetrachloride, and also reducing the amount of circulating water used for cooling the gas phase at the outlet of the scrubbing tower, thus saving resources and reducing costs. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a structural diagram of the present utility model;
[0020] Figure 2 This is a structural diagram of a high-efficiency heat exchanger.
[0021] Reference numerals in the attached figures: 1. Mixer; 2. Multiphase flow heat exchanger; 3. High-efficiency heat exchanger; 31. Shell; 32. Inlet end cap; 33. Outlet end cap; 34. Tube sheet; 35. Central tube; 36. Heat exchange tube; 37. Inlet pipe; 38. Outlet pipe; 4. Vaporizer; 5. Superheater. Detailed Implementation
[0022] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.
[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.
[0024] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.
[0025] like Figure 1 and Figure 2 As shown, this utility model discloses a cold hydrogenation heat recovery system, including a mixer 1. Silicon tetrachloride and hydrogen are fed into the mixer 1 for mixing. The outlet end of the mixer 1 is sequentially connected to a multiphase flow heat exchanger 2, a high-efficiency heat exchanger 3, a vaporizer 4, and a superheater 5. After the silicon tetrachloride and hydrogen are mixed in the mixer 1, a mixed gas is formed. The mixed gas is then sequentially passed into the multiphase flow heat exchanger 2, the high-efficiency heat exchanger 3, the vaporizer 4, and the superheater 5 to achieve gradual temperature increase.
[0026] The heat exchange chamber of the high-efficiency heat exchanger 3 is also connected to the heat exchange chamber of the multiphase flow heat exchanger 2. The gas phase from the scrubbing tower outlet is sequentially fed into the high-efficiency heat exchanger 3 and the multiphase flow heat exchanger 2. After the gas phase from the scrubbing tower outlet is fed into the heat exchange chamber of the high-efficiency heat exchanger 3 and exchanges heat with the mixed gas, the gas phase from the scrubbing tower outlet is then fed into the heat exchange chamber of the multiphase flow heat exchanger 2 and exchanges heat with the mixed gas. Finally, the gas phase from the scrubbing tower outlet is output, realizing two heat exchanges of the gas phase from the scrubbing tower outlet and improving the heat utilization rate.
[0027] Hydrogen gas at 40℃-50℃ and silicon tetrachloride gas at 40℃-50℃ enter mixer 1 and mix. After mixing, the temperature of the mixed gas decreases to 35-40℃. The mixed gas first enters multiphase flow heat exchanger 2 to exchange heat with the gas phase at the outlet of the scrubbing tower, and the mixed gas is heated to 75℃-80℃. Then, the mixed gas enters high-efficiency heat exchanger 3 to exchange heat with the gas phase at the outlet of the scrubbing tower, and the mixed gas is heated to 130℃. The mixed gas then passes through vaporizer 4 and superheater 5 in sequence, and is heated to 135-140℃ and 160-170℃ by water steam, respectively. After the gas phase at the outlet of the scrubbing tower passes through high-efficiency heat exchanger 3 and multiphase flow heat exchanger 2 in sequence to exchange heat with the mixed gas, the temperature drops from 140℃ to about 90℃.
[0028] By utilizing the heat of the gas phase at the outlet of the scrubbing tower, the amount of steam required for heating the mixture of hydrogen and silicon tetrachloride can be reduced, as can the amount of circulating water used for cooling the gas phase at the outlet of the scrubbing tower, thus saving resources and reducing costs.
[0029] The high-efficiency heat exchanger 3 is a single-flow heat exchanger. The high-efficiency heat exchanger 3 includes a shell 31. The shell 31 is provided with an inlet end cap 32 and an outlet end cap 33 at both ends. Tube sheets 34 are provided inside the inlet end cap 32 and the outlet end cap 33 respectively. A central cylinder 35 is provided between the two tube sheets 34 and is located in the middle of the shell 31. The two ends of the central cylinder 35 are diameter reduction sections near the tube sheets 34.
[0030] Multiple heat exchange tubes 36 arranged in a spiral pattern are wound around the outer side of the central cylinder 35. These heat exchange tubes 36 are arranged in a multi-layer structure and wound sequentially around the central cylinder 35. Both ends of the heat exchange tubes 36 are connected to the tube sheet 34 and communicate with the corresponding inlet end cap 32 and outlet end cap 33, respectively. The spiral angle of the heat exchange tubes 36 is 15°, the diameter of the heat exchange tubes 36 is φ19-φ25, the center distance of the heat exchange tubes 36 is 25mm-28mm, the gap between the heat exchange tubes 36 is 1mm-2mm, and the layer gap is 1mm-1.5mm. Adjacent layers of heat exchange tubes 36 are wound in opposite directions (spiral directions opposite) to ensure optimal heat exchange performance. The bending radius of the heat exchange tubes 36 at the diameter reduction section of the central cylinder 35 is 10D-15D, effectively preventing material erosion of the bends.
[0031] An inlet pipe 37 and an outlet pipe 38 are provided on the shell 31 between the two tube sheets 34, respectively, located near the two sides of the tube sheets 34. During heat exchange in the high-efficiency heat exchanger 3, the inlet pipe 37 and outlet pipe 38 serve as the inlet and outlet of the shell side, while the inlet end cap 32 and outlet end cap 33 serve as the inlet and outlet of the tube side. Gas from the multiphase flow heat exchanger 2 is introduced into the shell side, and the outlet gas phase from the scrubbing tower is introduced into the tube side; the two gases undergo efficient heat exchange in the heat exchanger. The temperature difference between the tube side and the shell side is controlled to within 10°C.
[0032] The above embodiments are merely preferred embodiments of this utility model and are not intended to limit the technical solutions of this utility model. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of this utility model patent.
Claims
1. A cold hydrogenation heat recovery system, characterized by, The utility model relates to a silicon tetrachloride hydrogenation device, including: a mixer, silicon tetrachloride and hydrogen are sent into the mixer to mix; wherein, the mixer outlet end is sequentially communicated with a multiphase flow heat exchanger, a high-efficiency heat exchanger, a vaporizer and a superheater, the heat exchange cavity of the high-efficiency heat exchanger is communicated with the heat exchange cavity of the multiphase flow heat exchanger, and the outlet gas phase of a washing tower is sequentially delivered into the high-efficiency heat exchanger and the multiphase flow heat exchanger.
2. The cold hydrogenation heat recovery system of claim 1, wherein, The high-efficiency heat exchanger includes a shell, two ends in the shell are respectively provided with tube sheets, a plurality of heat exchange tubes arranged in spiral tracks are arranged between the two tube sheets, and a gas inlet pipe and a gas outlet pipe are communicated on the shell between the two tube sheets.
3. The cold hydrogenation heat recovery system of claim 2, wherein, The shell is respectively provided with a gas inlet end and a gas outlet end at both ends, and the two tube sheets are respectively arranged in the gas inlet end and the gas outlet end.
4. The cold hydrogenation heat recovery system of claim 2, wherein, A center cylinder is arranged between the two tube sheets and in the middle of the shell, and a plurality of heat exchange tubes are wound outside the center cylinder.
5. The cold hydrogenation heat recovery system of claim 4, wherein, The center cylinder is a reduced diameter section near the tube sheet at both ends, and the bending radius of the heat exchange tube at the reduced diameter section of the center cylinder is 10D-15D.
6. The cold hydrogenation heat recovery system of claim 4, wherein, A plurality of heat exchange tubes are sequentially wound outside the center cylinder in a multilayer structure, and adjacent two layers of heat exchange tubes are oppositely wound.
7. The cold hydrogenation heat recovery system of claim 6, wherein, The gap between the heat exchange tubes is 1mm-2mm, and the interlayer gap is 1mm-1.5mm.
8. The cold hydrogenation heat recovery system of claim 2, wherein, The spiral angle of the heat exchange tube is 15°, the diameter of the heat exchange tube is φ19-φ25, and the center distance of the heat exchange tube is 25mm-28mm.