A comprehensive utilization system of waste heat from polysilicon production

Abstract

The present invention discloses a comprehensive utilization system of waste heat from polysilicon production, including a reduction furnace, the reduction furnace being connected with a bell jar heat utilization unit, the bell jar heat utilization unit utilizing the heat generated by the bell jar to form a first steam, and utilizing the first steam to vaporize and overheat trichlorosilane and then supply the steam to the reduction furnace; and / or a chassis heat utilization unit, the chassis heat utilization unit utilizing the heat generated by the chassis to circulate and cool the reduction furnace; and / or a tail gas waste heat utilization unit, the tail gas waste heat utilization unit utilizing the tail gas heat exchange to form a second steam and utilizing the tail gas after heat exchange to preheat trichlorosilane. The bell jar heat, chassis heat and tail gas waste heat can be fully utilized to improve the waste heat utilization efficiency of the overall system.

Description

Technical Field

[0001] The invention relates to the field of polysilicon production, and in particular to a system for comprehensively utilizing waste heat from polysilicon production. Background Art

[0002] Polysilicon is an ultra-high purity material used in the fields of integrated circuits, electronic devices and solar cells. In the polysilicon reduction production process, the working principle of the reduction furnace is to react the high-temperature silicon core with a mixed gas of trichlorosilane and hydrogen by powering on to generate polysilicon and deposit it on the silicon core. The reaction in the reduction furnace is a vapor deposition reaction that occurs on the surface of a silicon core at around 1050 degrees Celsius. The reaction consumes a large amount of electrical energy, and excess heat needs to be taken away by the reduction furnace cooling water to maintain the temperature in the reduction furnace. The heat taken away by the cooling water is cooled by circulating water through a heat exchanger, and then sent to the reduction furnace bell, chassis, electrodes and reduction furnace exhaust for cooling.

[0003] There is a large amount of heat in the bell jar, chassis heat and tail gas of the reduction furnace. During the operation of the reduction furnace, the heat taken away by the bell jar of the reduction furnace is about 55% of the total power consumption, accounting for most of the energy consumption, and the remaining 45% of the heat is taken away by the chassis of the reduction furnace, electrodes and tail gas. The existing waste heat utilization system mainly uses tail gas heat exchangers and hydrogen heaters to utilize the waste heat of tail gas. The temperature of the tail gas after heat exchange is high, and the waste heat in the tail gas is not fully utilized. For the tail gas recovery system, more circulating water and cooling capacity are consumed, resulting in energy waste. At the same time, it does not involve the unified recycling of the bell jar and chassis heat. The utilization rate of the bell jar, chassis heat and tail gas heat is low, which indirectly brings about problems such as high power consumption, large heat loss and high production cost. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of low efficiency of waste heat utilization of reduction furnaces in the prior art, and to provide a comprehensive utilization system for waste heat from polysilicon production.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] The invention mainly provides a comprehensive utilization system of waste heat from polysilicon production, including a reduction furnace, to which is connected:

[0007] A bell jar heat utilization unit, wherein the bell jar heat utilization unit utilizes the heat generated by the bell jar to form a first steam, and utilizes the first steam to vaporize and overheat trichlorosilane before supplying the first steam to the reduction furnace;

[0008] and / or a chassis heat utilization unit, wherein the chassis heat utilization unit utilizes the heat generated by the chassis to cyclically cool the reduction furnace;

[0009] and / or a tail gas waste heat utilization unit, wherein the tail gas waste heat utilization unit utilizes the tail gas for heat exchange to form second steam and utilizes the tail gas after heat exchange to preheat trichlorosilane.

[0010] As a preferred option, a system for comprehensive utilization of waste heat from polysilicon production, the bell jar heat utilization unit comprises a first high-temperature water tank, a trichlorosilane vaporizer and a trichlorosilane superheater are connected to the first high-temperature water tank, the trichlorosilane vaporizer is connected to the trichlorosilane superheater, and the trichlorosilane superheater is also connected to the reduction furnace;

[0011] The chassis heat utilization unit includes a waste heat utilization unit, the waste heat utilization unit is connected to a chassis water tank, and the chassis water tank is connected to the reduction furnace;

[0012] The exhaust gas waste heat utilization unit includes a reducing exhaust gas heat exchange device, to which a second high-temperature water tank and a hydrogen heating device are respectively connected, and to which a trichlorosilane preheater is connected, and the trichlorosilane preheater is also connected to the trichlorosilane vaporizer.

[0013] As a preferred option, in a system for comprehensive utilization of waste heat from polysilicon production, the second high-temperature water tank and the first high-temperature water tank are both flash tanks.

[0014] As a preferred option, in a system for comprehensive utilization of waste heat from polysilicon production, the second high-temperature water tank is a flash tank that produces 0.5MPa to 1.5MPa steam, and the first high-temperature water tank is a flash tank that produces 0.1MPa to 0.5MPa steam.

[0015] As a preferred option, a system for comprehensive utilization of waste heat from polysilicon production, wherein the hydrogen heating device includes a hydrogen heater.

[0016] As a preferred option, a system for comprehensive utilization of waste heat from polysilicon production is provided, wherein the waste heat utilization unit includes a lithium bromide heat pump and a lithium bromide refrigerator.

[0017] As a preferred option, a system for comprehensive utilization of waste heat from polysilicon production, wherein the reduction tail gas heat exchange device includes a heat exchanger.

[0018] As a preferred option, a system for comprehensive utilization of waste heat from polysilicon production, the trichlorosilane vaporizer includes a shell and a heat exchange tube, the heat exchange tube is arranged in the shell, and the heat exchange tube is connected to the first high-temperature water tank.

[0019] As a preferred option, a system for comprehensive utilization of waste heat from polysilicon production, wherein the trichlorosilane superheater comprises a steam boiler.

[0020] As a preferred option, a system for comprehensive utilization of waste heat from polysilicon production, wherein the trichlorosilane preheater is connected to a high-purity trichlorosilane delivery pipeline.

[0021] As a preferred option, in a system for comprehensive utilization of waste heat from polysilicon production, the chassis water tank is a stainless steel water tank.

[0022] It should be further explained that the technical features corresponding to the various options of the above system can be combined or replaced with each other to form a new technical solution without conflict.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The heat generated by the bell jar is utilized by the bell jar heat utilization unit, and the heat generated by the bell jar is used to form the first steam, and the first steam is used to vaporize and overheat trichlorosilane and then supplied to the reduction furnace to prepare for the raw material to enter the reduction furnace for reaction; the chassis heat utilization unit takes out the heat generated by the chassis through heat exchange and supplies it to other process applications. After the waste heat is utilized, the circulating water can cool the chassis of the reduction device to achieve the effect of continuous circulation and cooling. The tail gas waste heat utilization unit utilizes the waste heat of the tail gas. After the tail gas leaves the reduction furnace, it forms the second steam through heat exchange to provide heat for other devices in the plant area. The temperature of the tail gas after heat exchange decreases to a certain extent. The part of the waste heat carried by the tail gas after cooling can be used to heat the hydrogen. The tail gas heated by hydrogen can preheat the raw material trichlorosilane input into the reduction furnace. By comprehensively utilizing the three parts of waste heat, the waste heat utilization efficiency of the overall system is improved.

[0025] (2) In one example, the bell of the reduction furnace in the production process is cooled by a high-temperature water tank, and the water in the high-temperature water tank is vaporized to generate steam. Part of the steam is first used to vaporize trichlorosilane, and then the trichlorosilane is superheated to prepare for the raw material to enter the reduction furnace for reaction. The excess steam can be used for heat utilization by other devices in the plant. The heat generated by the chassis is taken out through heat exchange and utilized in the waste heat utilization unit. After the waste heat is utilized, the circulating water is stored in the chassis water tank and the chassis of the reduction device is cooled. After the tail gas leaves the reduction furnace, the water in the ultra-high temperature water tank is heated by the reduction tail gas heat exchange device to generate steam, which provides heat for other devices in the plant. The exhaust gas outlet temperature of the reduction tail gas heat exchange device can be used to heat hydrogen through the hydrogen heating device. Finally, the tail gas from the hydrogen heating device is supplied to the trichlorosilane preheater to utilize the waste heat of the raw material trichlorosilane. It can make full use of the heat of the bell, the heat of the chassis and the waste heat of the tail gas, reduce production costs and energy consumption, and achieve energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a system for comprehensive utilization of waste heat from polysilicon production according to an embodiment of the present invention;

[0027] Figure 2 This is a specific structural diagram of each waste heat utilization unit shown in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] In an exemplary embodiment, a system for comprehensive utilization of waste heat from polysilicon production is provided, comprising a reduction furnace, to which is connected:

[0033] A bell jar heat utilization unit, wherein the bell jar heat utilization unit utilizes the heat generated by the bell jar to form a first steam, and utilizes the first steam to vaporize and overheat trichlorosilane before supplying the first steam to the reduction furnace;

[0034] and / or a chassis heat utilization unit, wherein the chassis heat utilization unit utilizes the heat generated by the chassis to cyclically cool the reduction furnace;

[0035] and / or a tail gas waste heat utilization unit, wherein the tail gas waste heat utilization unit utilizes the tail gas for heat exchange to form second steam and utilizes the tail gas after heat exchange to preheat trichlorosilane.

[0036] Specifically, Figure 1 As shown, a schematic diagram of a bell heat utilization unit, a chassis heat utilization unit and a chassis heat utilization unit connected to a reduction furnace is given. The reduction furnace is in normal production and operation at 1050℃, and a large amount of heat is generated during the production process; it radiates to the outside through the bell and chassis of the reduction furnace equipment, causing heat pollution and waste; in addition, the tail gas generated during the production process of the reduction furnace also carries a large amount of heat. This system utilizes the heat generated by the reduction furnace, which is mainly divided into three parts. The first part utilizes the bell heat during the production process; the second part utilizes the chassis heat during the production process; and the third part utilizes the waste heat of the tail gas after the reaction.

[0037] The heat generated by the bell jar is utilized by the bell jar heat utilization unit, and the heat generated by the bell jar is used to form the first steam, and the first steam is used to vaporize and overheat trichlorosilane and then supplied to the reduction furnace to prepare for the raw material to enter the reduction furnace for reaction; the chassis heat utilization unit takes out the heat generated by the chassis through heat exchange and supplies it to other process applications. After the waste heat is utilized, the circulating water can cool down the chassis of the reduction device to achieve the effect of continuous circulation and cooling. The tail gas waste heat utilization unit utilizes the waste heat of the tail gas. After the tail gas leaves the reduction furnace, it forms the second steam through heat exchange to provide heat for other devices in the plant area. The temperature of the tail gas after heat exchange drops to a certain extent. The part of the waste heat carried by the tail gas after cooling can be used to heat the hydrogen. The tail gas heated by hydrogen can preheat the raw material trichlorosilane input into the reduction furnace. By comprehensively utilizing the three parts of waste heat, the waste heat utilization efficiency of the overall system is improved.

[0038] In one example, if Figure 2 As shown, a specific structure of a comprehensive utilization system of waste heat from polysilicon production is provided, wherein the bell jar heat utilization unit comprises a first high-temperature water tank, a trichlorosilane vaporizer and a trichlorosilane superheater are connected to the first high-temperature water tank, the trichlorosilane vaporizer is connected to the trichlorosilane superheater, and the trichlorosilane superheater is also connected to the reduction furnace;

[0039] The chassis heat utilization unit includes a waste heat utilization unit, the waste heat utilization unit is connected to a chassis water tank, and the chassis water tank is connected to the reduction furnace;

[0040] The exhaust gas waste heat utilization unit includes a reducing exhaust gas heat exchange device, to which a second high-temperature water tank and a hydrogen heating device are respectively connected, and to which a trichlorosilane preheater is connected, and the trichlorosilane preheater is also connected to the trichlorosilane vaporizer.

[0041] Among them, the bell jar of the reduction furnace in the production process is cooled by the first high-temperature water tank, and the water in the first high-temperature water tank is vaporized to generate steam (first steam). Part of the steam is first used to vaporize trichlorosilane, and then the trichlorosilane is overheated to prepare for the raw material to enter the reduction furnace for reaction. The excess steam can be used for heat utilization by other devices in the plant. The heat generated by the chassis is brought out through heat exchange and utilized in the waste heat utilization unit. After the waste heat is utilized, the circulating water is stored in the chassis water tank and the chassis of the reduction device is cooled. After the tail gas leaves the reduction furnace, the water in the ultra-high temperature water tank is heated by the reduction tail gas heat exchange device to generate steam (second steam) to provide heat for other devices in the plant. The tail gas outlet temperature of the reduction tail gas heat exchange device can be used to heat the hydrogen through the hydrogen heating device. Finally, the tail gas from the hydrogen heating device is supplied to the trichlorosilane preheater to utilize the waste heat of the raw material trichlorosilane.

[0042] In one example, a system for comprehensive utilization of waste heat from polysilicon production, the second high-temperature water tank and the first high-temperature water tank are both flash tanks. The second high-temperature water tank is a flash tank that produces 0.5MPa to 1.5MPa steam, and the first high-temperature water tank is a flash tank that produces 0.1MPa to 0.5MPa steam. Among them, the first high-temperature water tank cools down the bell of the reduction furnace during the production process, vaporizes the water in the high-temperature water tank, and forms 0.1MPa to 0.5MPa steam. The 0.1MPa to 0.5MPa steam is first supplied to the trichlorosilane vaporizer, and the trichlorosilane vaporizer heats the trichlorosilane vaporizer with the 0.1MPa to 0.5MPa steam generated by the first high-temperature water tank, raises the temperature of the trichlorosilane, and vaporizes the liquid phase trichlorosilane into a gas phase. Secondly, 0.1MPa~0.5MPa steam is supplied to the trichlorosilane superheater to superheat the trichlorosilane and further heat the trichlorosilane vaporized by the trichlorosilane vaporizer to prepare for the trichlorosilane to enter the reduction furnace for reaction. Finally, the excess 0.1MPa~0.5MPa steam can be used for heat utilization by other devices in the plant.

[0043] In one example, a system for comprehensive utilization of waste heat from polysilicon production, the reduction tail gas heat exchange device includes a heat exchanger. The reduction tail gas temperature is about 400℃~500℃. After the tail gas leaves the reduction furnace, it heats the water in the second high-temperature water tank through the heat exchanger to generate 0.5MPa~1.5MPa steam to provide heat for other devices in the plant area. The outlet temperature of the heat exchanger tail gas is 100℃~300℃. This part of the waste heat can be used to heat the hydrogen through the hydrogen heating device to raise the temperature of the hydrogen to the production temperature requirement. Finally, the tail gas from the hydrogen heating device is introduced into the trichlorosilane preheater to utilize the waste heat of the raw trichlorosilane, preheat the high-purity trichlorosilane, and prepare for the trichlorosilane vaporizer to vaporize the trichlorosilane.

[0044] In one example, a comprehensive waste heat utilization system for polysilicon production, the waste heat utilization unit uses circulating water to remove the heat from the reduction furnace chassis, and the removed heat is distributed according to production needs through the waste heat system. The waste heat utilization unit includes waste heat utilization devices such as lithium bromide heat pumps, lithium bromide refrigerators, and living area heating. After the waste heat is utilized, the circulating water is stored in the chassis water tank and the chassis of the reduction device is cooled.

[0045] In one example, a system for comprehensive utilization of waste heat from polysilicon production is provided, wherein the hydrogen heating device includes a hydrogen heater.

[0046] In one example, a system for comprehensive utilization of waste heat from polysilicon production is provided, wherein the trichlorosilane vaporizer comprises a shell and a heat exchange tube, wherein the heat exchange tube is arranged in the shell, and the heat exchange tube is connected to the first high-temperature water tank.

[0047] In one example, a system for comprehensive utilization of waste heat from polysilicon production is provided, wherein the trichlorosilane superheater comprises a steam boiler.

[0048] In one example, a system for comprehensive utilization of waste heat from polysilicon production is provided, wherein a high-purity trichlorosilane delivery pipeline is connected to the trichlorosilane preheater.

[0049] In one example, a system for comprehensive utilization of waste heat from polysilicon production, the chassis water tank is a stainless steel water tank.

[0050] Furthermore, the operation mode of each device can be controlled according to the heat proportion of the bell jar, chassis and exhaust waste heat, so as to fully improve the waste heat utilization rate and reasonably use the equipment resources.

[0051] Furthermore, the temperature of each part of the existing reduction furnace is automatically adjusted according to the cooling water flow. Each water tank is equipped with safety accessories such as pressure gauges and thermometers. The cooling water part is equipped with a frequency conversion pump to control the pressure of the water main pipe of each part to ensure the pressure and flow of the cooling water. The system is also designed with a water supply pipeline, which is equipped with a regulating valve, flow meter and pressure gauge to ensure the precise control of each part of the equipment and the stability of the system.

[0052] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A system for comprehensive utilization of waste heat from polysilicon production, comprising a reduction furnace, characterized in that: The reduction furnace is connected with: A bell jar heat utilization unit, wherein the bell jar heat utilization unit utilizes the heat generated by the bell jar to form a first steam, and utilizes the first steam to vaporize and overheat trichlorosilane before supplying the first steam to the reduction furnace; A chassis heat utilization unit, wherein the chassis heat utilization unit utilizes the heat generated by the chassis to cyclically cool the reduction furnace; A tail gas waste heat utilization unit, wherein the tail gas waste heat utilization unit utilizes the tail gas for heat exchange to form a second steam and utilizes the tail gas after heat exchange to preheat trichlorosilane; The bell jar heat utilization unit comprises a first high-temperature water tank, to which a trichlorosilane vaporizer and a trichlorosilane superheater are connected, the trichlorosilane vaporizer is connected to the trichlorosilane superheater, and the trichlorosilane superheater is also connected to the reduction furnace; the bell jar of the reduction furnace in the production process is cooled by the first high-temperature water tank, and the water in the first high-temperature water tank is vaporized to generate first steam, part of the first steam is firstly used to vaporize trichlorosilane, and then the trichlorosilane is superheated to prepare for the raw material to enter the reduction furnace for reaction, and the excess first steam is used for heat utilization of other devices in the plant area; The chassis heat utilization unit includes a waste heat utilization unit, the waste heat utilization unit is connected to a chassis water tank, and the chassis water tank is connected to the reduction furnace; The tail gas waste heat utilization unit comprises a reduction tail gas heat exchange device, the reduction tail gas heat exchange device is respectively connected to a second high temperature water tank and a hydrogen heating device, the hydrogen heating device is connected to a trichlorosilane preheater, and the trichlorosilane preheater is also connected to the trichlorosilane vaporizer; after the tail gas leaves the reduction furnace, the ultra-high temperature water tank water is heated by the reduction tail gas heat exchange device to generate second steam, which provides heat for other devices in the plant area; The operation mode of each device is controlled according to the heat proportion of the bell jar heat, chassis heat and exhaust waste heat.

2. A system for comprehensive utilization of waste heat from polysilicon production according to claim 1, characterized in that: The second high temperature water tank and the first high temperature water tank are both flash tanks.

3. A system for comprehensive utilization of waste heat from polysilicon production according to claim 2, characterized in that: The second high temperature water tank is a flash tank that generates steam at 0.5 MPa to 1.5 MPa, and the first high temperature water tank is a flash tank that generates steam at 0.1 MPa to 0.5 MPa.

4. The system for comprehensive utilization of waste heat from polysilicon production according to claim 1, characterized in that: The hydrogen heating device comprises a hydrogen heater.

5. The system for comprehensive utilization of waste heat from polysilicon production according to claim 1, characterized in that: The waste heat utilization unit includes a lithium bromide heat pump and a lithium bromide refrigerator.

6. The system for comprehensive utilization of waste heat from polysilicon production according to claim 1, characterized in that: The reducing tail gas heat exchange device comprises a heat exchanger.

7. The system for comprehensive utilization of waste heat from polysilicon production according to claim 1, characterized in that: The trichlorosilane vaporizer includes a shell and a heat exchange tube. The heat exchange tube is arranged in the shell and connected to the first high-temperature water tank.

8. The system for comprehensive utilization of waste heat from polysilicon production according to claim 1, characterized in that: The trichlorosilane superheater includes a steam boiler.

9. The system for comprehensive utilization of waste heat from polysilicon production according to claim 1, characterized in that: The trichlorosilane preheater is connected with a high-purity trichlorosilane delivery pipeline.

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