Distilled water recycling system of MVR (Mechanical Vapor Recompression) device in polycrystalline silicon production

Abstract

The utility model relates to the technical field of polycrystalline silicon production equipment, in particular to a distilled water recycling system of an MVR (Mechanical Vapor Recompression) device in polycrystalline silicon production. The steam preheater is communicated with the distilled water preheater; the forced circulation heat exchanger is communicated with the steam preheater; the forced circulation pump is communicated with the forced circulation heat exchanger; an inlet of the crystal separator is communicated with the forced circulation pump; the secondary separator is communicated with the crystallization separator; the steam compressor is communicated with the secondary separator; the liquid accumulation tank is respectively communicated with the steam compressor and the secondary separator; the distilled water tank is respectively communicated with the steam preheater, the forced circulation heat exchanger and the liquid accumulation tank; the distilled water preheater is communicated with the distilled water tank; the circulating water heat exchanger is communicated with the distilled water preheater; the condensate water tank is communicated with the circulating water heat exchanger; and the steam compressor is communicated with the condensed water tank. According to the utility model, the cyclic utilization of distilled water can be realized, and the use amount of desalted water is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon production equipment, in particular to a distilled water recycling system of an MVR device in polysilicon production. Background Art

[0002] During the Siemens process for producing polysilicon, the slag slurry and chlorosilane-containing waste gas are hydrolyzed into chlorine-containing acidic wastewater and silica. Alkali is added to the acidic wastewater to neutralize it into high-salt wastewater. The high-salt wastewater undergoes evaporation and crystallization in an MVR device. During the evaporation and crystallization process, the steam is treated in a crystallizer and then compressed in a steam compressor, achieving energy conversion. This secondary steam enthalpy increases, raising its temperature. The compressed steam enters a heat exchanger to heat the material. After heat exchange, the steam condenses into water and flows to a condensate tank for use as circulating water and backwash water for the sand filter. It is then discharged after use. The steam compressor outlet in the MVR system produces superheated, saturated steam, which requires cooling. Furthermore, the temperature difference between the inlet and outlet of the steam compressor must be controlled within a predetermined range. Excessive temperature differences result in significant energy consumption, increasing equipment operating costs. Furthermore, excessive temperature differences in the cooling liquid can affect the normal operation of the equipment and reduce its service life. In the prior art, the desuperheating water used to cool the steam compressor is 35°C desalted water, which is used in large quantities and has a high cost. Utility Model Content

[0003] In view of this, the utility model provides a distilled water recycling system for an MVR device in polysilicon production, the main purpose of which is to realize the recycling of distilled water, reduce resource waste, and at the same time reduce the use of desalted water and save production costs.

[0004] In order to achieve the above-mentioned purpose, the present invention mainly provides the following technical solutions:

[0005] The embodiment of the utility model provides a distilled water recycling system for an MVR device in polysilicon production, comprising: a distilled water preheater, a steam preheater, a forced circulation heat exchanger, a forced circulation pump, a crystallizer separator, a secondary separator, a steam compressor, a distilled water tank, a liquid accumulation tank, a circulating water heat exchanger, and a condensed water tank;

[0006] The material inlet of the distilled water preheater is used to input MVR raw liquid;

[0007] The material inlet of the steam preheater is connected to the material outlet of the distilled water preheater;

[0008] The material inlet of the forced circulation heat exchanger is connected to the material outlet of the steam preheater;

[0009] The inlet of the forced circulation pump is communicated with the material outlet of the forced circulation heat exchanger;

[0010] The inlet of the crystallization separator is communicated with the outlet of the forced circulation pump; the crystallization separator is provided with a crystallized salt outlet;

[0011] The inlet of the secondary separator is in communication with the mixing outlet of the crystallization separator;

[0012] The steam inlet of the steam compressor is in communication with the steam outlet of the secondary separator;

[0013] The liquid inlet of the liquid accumulation tank is connected to the cooling water outlet of the steam compressor and the liquid outlet of the secondary separator respectively;

[0014] The liquid inlet of the distilled water tank is connected to the medium outlet of the steam preheater, the medium outlet of the forced circulation heat exchanger, and the outlet of the liquid storage tank respectively; the medium inlet of the steam preheater is used to input fresh steam;

[0015] The medium inlet of the distilled water preheater is communicated with the liquid outlet of the distilled water tank;

[0016] The material inlet of the circulating water heat exchanger is connected to the medium outlet of the distilled water preheater;

[0017] The inlet of the condensed water tank is connected to the material outlet of the circulating water heat exchanger;

[0018] The cooling water inlet of the steam compressor is communicated with the outlet of the condensed water tank.

[0019] Furthermore, the material in the condensed water tank is transported to the cooling water inlet of the steam compressor by a distilled water pump 1;

[0020] The material in the distilled water tank is transported to the medium inlet of the steam preheater by a second distilled water pump;

[0021] The material in the liquid accumulation tank is transported to the distilled water tank through the distilled water pump three.

[0022] Furthermore, a temperature detection device is provided at the steam outlet of the steam compressor.

[0023] Furthermore, a flow regulating valve is provided on the pipeline between the condensed water tank and the cooling water inlet of the steam compressor.

[0024] By means of the above technical solution, the distilled water recycling system of the MVR device in polysilicon production of the present invention has at least the following advantages:

[0025] It can realize the recycling of distilled water, reduce the waste of resources, and at the same time reduce the use of desalted water, saving production costs.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a distilled water recycling system for an MVR device in polysilicon production provided by an embodiment of the present utility model. DETAILED DESCRIPTION

[0028] To further illustrate the technical means and effects employed by this utility model to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, provides a detailed description of the specific implementation methods, structures, features, and effects of this utility model application. 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.

[0029] like Figure 1 As shown, an embodiment of the present invention proposes a distilled water recycling system for an MVR device in polysilicon production, comprising: a distilled water preheater, a steam preheater, a forced circulation heat exchanger, a forced circulation pump, a crystallizer, a secondary separator, a steam compressor, a distilled water tank, a liquid accumulation tank, a circulating water heat exchanger and a condensed water tank; the material inlet of the distilled water preheater is used to input MVR raw liquid; the material inlet of the steam preheater is connected to the material outlet of the distilled water preheater; the material inlet of the forced circulation heat exchanger is connected to the material outlet of the steam preheater; the inlet of the forced circulation pump is connected to the material outlet of the forced circulation heat exchanger; the inlet of the crystallizer is connected to the outlet of the forced circulation pump; the crystallizer is provided with a crystallized salt outlet for Crystallized salt output; the inlet of the secondary separator is connected to the mixed outlet of the crystallizer; the steam inlet of the steam compressor is connected to the steam outlet of the secondary separator; the liquid inlet of the liquid accumulation tank is connected to the cooling water outlet of the steam compressor and the liquid outlet of the secondary separator respectively; the liquid inlet of the distilled water tank is connected to the medium outlet of the steam preheater, the medium outlet of the forced circulation heat exchanger, and the outlet of the liquid accumulation tank respectively; the medium inlet of the steam preheater is used to input fresh steam; the medium inlet of the distilled water preheater is connected to the liquid outlet of the distilled water tank; the material inlet of the circulating water heat exchanger is connected to the medium outlet of the distilled water preheater; the inlet of the condensed water tank is connected to the material outlet of the circulating water heat exchanger; the cooling water inlet of the steam compressor is connected to the outlet of the condensed water tank.

[0030] The steam generated by flash-evaporating high-salinity wastewater undergoes crystallization in a crystallizer. The steam then enters a secondary separator to separate liquid droplets entrained in the gas. The steam then enters a steam compressor for compression. Energy conversion in the steam compressor increases the enthalpy and temperature of the secondary steam. The compressed steam then enters a forced circulation heat exchanger to heat the material. During this heating process, the steam condenses into water and flows into a distilled water tank. Simultaneously, the condensate at the bottom of the secondary separator and the condensate from the steam compressor that enters the liquid storage tank are transferred to the distilled water tank. The distilled water is cooled to the required temperature through a distilled water preheater and a circulating water heat exchanger, where it is used as cooling water for the steam compressor.

[0031] An embodiment of the present invention proposes a distilled water recycling system for an MVR device in polysilicon production, which can realize the recycling of distilled water, reduce resource waste, and at the same time reduce the use of desalted water, saving production costs; and solves the problem of water unit consumption in the production of the polysilicon industry chain.

[0032] The comparative data of desalted water and distilled water are as follows:

[0033]

[0034]

[0035] After the distilled water is recycled to the steam compressor, the steam compressor operating data is as follows:

[0036]

[0037] The above data and analysis results confirm that the distilled water is recycled in the MVR device to meet production requirements. The distilled water is used as cooling water for the steam compressor with good operating effect and normal operating indicators.

[0038] Preferably, the material in the condensate tank is transported to the cooling water inlet of the steam compressor through distilled water pump 1; the material in the distilled water tank is transported to the medium inlet of the steam preheater through distilled water pump 2; the material in the liquid accumulation tank is transported to the distilled water tank by distilled water pump 3; the material is transported by distilled water pump 1, distilled water pump 2 and distilled water pump 3, and the transportation is stable and reliable.

[0039] Preferably, a temperature detection device is provided at the steam outlet of the steam compressor. Preferably, a flow control valve is provided on the pipeline between the condensate tank and the cooling water inlet of the steam compressor; the flow control valve is automatically adjusted to set the steam outlet temperature, and the cooling water volume is automatically adjusted according to the temperature.

[0040] In the description of this utility model, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0041] The standard parts used in this utility model can all be purchased from the market, and special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the existing technology. The machinery, parts and equipment all adopt conventional models in the existing technology, and the circuit connection adopts the conventional connection method in the existing technology, which will not be described in detail here.

[0042] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes, and modifications to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A distilled water recycling system for an MVR device in polysilicon production, characterized in that: Including: distilled water preheater, steam preheater, forced circulation heat exchanger, forced circulation pump, crystallizer separator, secondary separator, steam compressor, distilled water tank, liquid storage tank, circulating water heat exchanger and condensate tank; The material inlet of the distilled water preheater is used to input MVR raw liquid; The material inlet of the steam preheater is connected to the material outlet of the distilled water preheater; The material inlet of the forced circulation heat exchanger is connected to the material outlet of the steam preheater; The inlet of the forced circulation pump is communicated with the material outlet of the forced circulation heat exchanger; The inlet of the crystallization separator is communicated with the outlet of the forced circulation pump; the crystallization separator is provided with a crystallized salt outlet; The inlet of the secondary separator is in communication with the mixing outlet of the crystallization separator; The steam inlet of the steam compressor is in communication with the steam outlet of the secondary separator; The liquid inlet of the liquid accumulation tank is connected to the cooling water outlet of the steam compressor and the liquid outlet of the secondary separator respectively; The liquid inlet of the distilled water tank is connected to the medium outlet of the steam preheater, the medium outlet of the forced circulation heat exchanger, and the outlet of the liquid storage tank respectively; the medium inlet of the steam preheater is used to input fresh steam; The medium inlet of the distilled water preheater is communicated with the liquid outlet of the distilled water tank; The material inlet of the circulating water heat exchanger is connected to the medium outlet of the distilled water preheater; The inlet of the condensed water tank is connected to the material outlet of the circulating water heat exchanger; The cooling water inlet of the steam compressor is communicated with the outlet of the condensed water tank.

2. The distilled water recycling system of the MVR device in polysilicon production according to claim 1, characterized in that: The material in the condensed water tank is transported to the cooling water inlet of the steam compressor by a distilled water pump 1; The material in the distilled water tank is transported to the medium inlet of the steam preheater by a second distilled water pump; The material in the liquid accumulation tank is transported to the distilled water tank through the distilled water pump three.

3. The distilled water recycling system of the MVR device in polysilicon production according to claim 2, characterized in that: A temperature detection device is provided at the steam outlet of the steam compressor.

4. The distilled water recycling system of the MVR device in polysilicon production according to claim 3, characterized in that: A flow regulating valve is provided on the pipeline between the condensed water tank and the cooling water inlet of the steam compressor.

Images