High-boiling residue cracking tail gas circulating system

Abstract

The utility model provides a high-boiling-point substance cracking tail gas circulating system, which relates to the technical field of polycrystalline silicon, and comprises a reactor provided with a high-boiling-point substance inlet, a tail gas circulating inlet, a product liquid outlet and a tail gas outlet; an inlet of the compressor is connected with the tail gas outlet, and an outlet is directly or indirectly connected with the tail gas circulating inlet; wherein the high-boiling-point substance inlet is used for introducing a liquid-state high-boiling-point substance; the tail gas outlet is used for discharging tail gas containing HCL and silane gas; the reactor can supplement HCL gas; the reaction pressure of the reactor is less than 80kpaG, and the reaction temperature is less than 70 DEG C. The reaction pressure and the reaction temperature of the reactor are reduced, so that the system energy consumption is reduced. The compressor is connected with the tail gas outlet and the tail gas circulating inlet, on one hand, the tail gas pressure is increased, the tail gas can be returned to the reactor to be utilized, the material loss and water treatment cost generated by tail gas washing are reduced, and on the other hand, the stability of the primary conversion rate of the reactor is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon, in particular to a high-boiling substance cracking tail gas circulation system. Background Art

[0002] See also Figure 1 In the cracking reaction of polysilicon high-boiling products, liquid high-boiling products (mainly including Si2CL6) and HCL gas are introduced into the reactor for reaction, the obtained product liquid is poured into the product buffer tank, and the tail gas (including HCL and silane gas) is discharged from the top of the reactor. In the cracking reaction process, the reaction pressure and temperature of the reactor are very important and directly affect the operating cost of the system.

[0003] The reaction pressure of the original reactor is 80 ~ 120kpaG and the reaction temperature is 70℃. At this time, the tail gas (including HCL and silane gas) can be used in the downstream device for secondary utilization. The downstream device controls the pressure at 100 ~ 120kpaG, and it is washed and discharged after secondary recycling. However, this consumes more heat than the low-pressure operation of the reactor. At the same time, due to the unstable pressure of the recovered tail gas, the reaction pressure of the downstream device continues to fluctuate, and the primary conversion rate fluctuates greatly, resulting in unstable primary conversion rate.

[0004] In order to reduce the operating energy consumption, it is considered to reduce the reaction pressure and temperature of the reactor. However, if the reaction pressure of the reactor is controlled at 50kpaG, the tail gas cannot be directly recovered (the downstream device controls the pressure at 100 ~ 120kpaG), and can only be sent to the tail gas washing system, where the tail gas is washed with water and then discharged, resulting in the useful materials in the tail gas being washed with water and finally treated as hazardous waste, increasing the loss of materials and water treatment costs.

[0005] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that the information constitutes the prior art known to those skilled in the art. Utility Model Content

[0006] In view of the above situation, the utility model provides a high-boiling-substance cracking tail gas circulation system, aiming to solve the technical problems of high energy consumption and unstable primary conversion rate of the existing system.

[0007] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0008] The utility model provides a high boiling point cracking tail gas circulation system, comprising:

[0009] The reactor has a high boiling material inlet, an exhaust gas circulation inlet, a product liquid outlet and an exhaust gas outlet;

[0010] A compressor, wherein the inlet of the compressor is connected to the exhaust gas outlet, and the outlet is directly or indirectly connected to the exhaust gas circulation inlet;

[0011] The high boiling point inlet is used to introduce liquid high boiling points; the tail gas outlet is used to discharge tail gas containing HCL and silane gas; the reactor can be supplemented with HCL gas;

[0012] The reaction pressure of the reactor is less than 80 kpaG and the reaction temperature is less than 70°C.

[0013] In some embodiments of the present invention, the reaction pressure of the reactor is 50 kPaG.

[0014] In some embodiments of the present invention, the reaction temperature of the reactor is 55-60°C.

[0015] In some embodiments of the present invention, an HCL supplement port is connected to the inlet of the compressor.

[0016] In some embodiments of the utility model, a cooler is further included; the inlet of the cooler is connected to the outlet of the compressor, and the outlet is connected to the inlet of the exhaust gas circulation.

[0017] In some embodiments of the utility model, a condenser is further included; the gas phase inlet of the condenser is connected to the exhaust gas outlet; and the gas phase outlet of the condenser is connected to the inlet of the compressor.

[0018] In some embodiments of the present invention, a product buffer tank is further included; the product buffer tank has a product liquid inlet, and the product liquid inlet is connected to the product liquid outlet.

[0019] In some embodiments of the present invention, the product buffer tank further has a product condensate inlet, and the product condensate inlet is connected to the liquid phase outlet of the condenser.

[0020] The embodiments of the present invention have at least the following advantages or beneficial effects:

[0021] This embodiment reduces the reaction pressure and reaction temperature of the reactor to reduce system energy consumption. The tail gas outlet and the tail gas circulation inlet are connected by a compressor. On the one hand, the tail gas pressure is increased, so that the tail gas can be returned to the reactor for use, reducing the material loss and water treatment costs caused by tail gas washing. On the other hand, the stable operation of the compressor solves the problem of unstable pressure of the recovered tail gas, ensuring the stability of the reactor's primary conversion rate.

[0022] Other features and advantages of the present invention will be set forth in the following description, and in part will become apparent from the description, or may be understood by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a structural diagram of the existing system;

[0025] Figure 2 This is a schematic diagram of the structure of the high-boiling-material cracking tail gas circulation system provided in an embodiment of the present application.

[0026] Icon: 1-reactor, 2-compressor, 3-cooler, 4-condenser, 5-product buffer tank. DETAILED DESCRIPTION

[0027] In the following, only some exemplary embodiments are briefly described. As those skilled in the art can appreciate, the described embodiments can be modified in various different ways without departing from the spirit or scope of the embodiments of the present invention.

[0028] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0029] The embodiments of the present utility model are described in detail below with reference to the accompanying drawings.

[0030] See also Figure 1-2 This embodiment provides a high-boiling-material cracking tail gas circulation system, including a reactor, a compressor and a cooler.

[0031] The reactor has a high boiling material inlet and an exhaust gas circulation inlet at the bottom and a product liquid outlet and an exhaust gas outlet at the top; the high boiling material inlet is used to introduce liquid high boiling materials, which mainly include Si2CL6; the product liquid outlet is used to discharge the product liquid; the exhaust gas outlet is used to discharge the exhaust gas, which includes HCL and silane gas; the exhaust gas circulation inlet is used to connect with the exhaust gas outlet.

[0032] The reaction pressure of the reactor is less than 80 kpaG, and the reaction temperature is less than 70°C. Those skilled in the art can select appropriate reaction pressure and reaction temperature as needed. Preferably, in this embodiment, the reaction pressure of the reactor is 50 kpaG, and the reaction temperature is 55-60°C. Compared with the prior art, this embodiment reduces the reaction pressure and reaction temperature of the reactor. After changing the reaction pressure and reaction temperature of the reactor, the supporting equipment (pressure supply, heat supply) of the reactor is adaptively adjusted to provide the above conditions.

[0033] The inlet of the compressor is connected to the exhaust gas outlet, and the outlet is connected to the inlet of the cooler.

[0034] The outlet of the cooler is connected to the exhaust gas circulation inlet.

[0035] This embodiment reduces the reaction pressure and reaction temperature of the reactor, and in particular, configures the reactor to have a reaction pressure of 50 kPaG and a reaction temperature of 55 to 60°C to reduce system energy consumption. The exhaust gas outlet and the exhaust gas circulation inlet are connected by a compressor. On the one hand, the exhaust gas pressure is increased, so that the exhaust gas can be returned to the reactor for use, reducing the material loss and water treatment costs generated by exhaust gas washing. On the other hand, the stably operated compressor solves the problem of unstable pressure of the recovered exhaust gas, ensuring the stability of the reactor's primary conversion rate.

[0036] Based on the working characteristics of the compressor, the outlet temperature of the compressor may be higher than the reaction temperature of the reactor; when the outlet temperature of the compressor is higher than the reaction temperature of the reactor, the temperature of the exhaust gas entering the exhaust gas circulation inlet can be matched with the reaction temperature through the setting of the cooler.

[0037] It can be understood that the reactor should be able to be supplemented with HCl gas, the reactor has an HCl supplement port, or the inlet of the compressor is connected to the HCl supplement port.

[0038] The high-boiling-substance cracking tail gas circulation system also includes a condenser; the gas phase inlet of the condenser is connected to the tail gas outlet; the gas phase outlet of the condenser is connected to the inlet of the compressor; the liquid phase outlet of the condenser is used to discharge the product condensate, which can be combined with the product liquid and then sent out. The components of the product condensate and the product liquid are the same because: the reaction in the reactor is a gas-liquid reaction, and the liquid after the reaction mainly enters the product buffer tank through the product liquid outlet. The tail gas will carry part of the product liquid into the condenser. The condenser condenses and recovers most of the product liquid carried by the unreacted gas, and a small part enters the compressor circulation with the tail gas.

[0039] The high-boiling-material cracking tail gas circulation system further includes a product buffer tank; the product buffer tank has a product liquid inlet, which is connected to the product liquid outlet. In this embodiment, in order to facilitate the merging of the product condensate and the product liquid, the product buffer tank also has a product condensate inlet, which is connected to the liquid phase outlet of the condenser.

[0040] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. In the absence of conflicts, the embodiments of the present application and the features in the embodiments may be combined with each other at will. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high boiling point cracking tail gas circulation system, characterized in that: include: The reactor has a high boiling material inlet, an exhaust gas circulation inlet, a product liquid outlet and an exhaust gas outlet; A compressor, wherein the inlet of the compressor is connected to the exhaust gas outlet, and the outlet is directly or indirectly connected to the exhaust gas circulation inlet; The high-boiling-substance inlet is used to introduce liquid high-boiling-substances; the tail gas outlet is used to discharge tail gas containing HCL and silane gas; and the reactor can be supplemented with HCL gas; The reaction pressure of the reactor is less than 80 kPaG and the reaction temperature is less than 70°C.

2. The high-boiling-material cracking tail gas circulation system according to claim 1, characterized in that: The reaction pressure of the reactor is 50 kpaG.

3. The high boiling point cracking tail gas circulation system according to claim 2, characterized in that: The reaction temperature of the reactor is 55-60°C.

4. The high-boiling-material cracking tail gas circulation system according to claim 1, characterized in that: The inlet of the compressor is connected with an HCL replenishing port.

5. The high-boiling-substance cracking tail gas circulation system according to claim 1, characterized in that: It also includes a cooler; the inlet of the cooler is connected to the outlet of the compressor, and the outlet is connected to the exhaust gas circulation inlet.

6. The high boiling matter cracking tail gas circulation system according to any one of claims 1 to 5, characterized in that: It also includes a condenser; the gas phase inlet of the condenser is connected to the tail gas outlet; the gas phase outlet of the condenser is connected to the inlet of the compressor.

7. The high-boiling-material cracking tail gas circulation system according to claim 6, characterized in that: It also includes a product buffer tank; the product buffer tank has a product liquid inlet, and the product liquid inlet is connected to the product liquid outlet.

8. The high-boiling-substance cracking tail gas circulation system according to claim 7, characterized in that: The product buffer tank also has a product condensate inlet, and the product condensate inlet is connected to the liquid phase outlet of the condenser.

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