STRO membrane desalting water device for polycrystalline silicon production plant

Abstract

The utility model discloses an STRO membrane desalted water device for a polycrystalline silicon production plant. The STRO membrane desalted water device comprises a multi-stage security filter, a high-pressure pump, a circulating pump and a group of STRO membrane filtering modules, the multi-stage security filter, the high-pressure pump and the circulating pump are sequentially connected through a pipeline; all the STRO membrane filtration modules are connected through parallel pipelines, and sewage is respectively fed into all the STRO membrane filtration modules for treatment through a circulating pump. The device can tolerate higher suspended matter content through the STRO membrane, and is easy to clean and maintain, small in dependence on biological pretreatment, high in filtering stability and high in operation safety. The occupied area is small, the service life is long, and the energy consumption is low. Strong brine generated by filtration enters the pretreatment system to be recycled again, so that the discharge capacity is reduced, and the utilization rate of water resources is improved.

Description

Technical Field

[0001] The utility model belongs to the field of polysilicon production, and in particular relates to a STRO membrane desalination device for a polysilicon production plant. Background Art

[0002] With the acceleration of urbanization and the improvement of people's living standards, the discharge of domestic sewage is also increasing. Domestic sewage contains large amounts of organic matter, nitrogen, phosphorus and other pollutants. If not effectively treated, it will cause serious harm to the environment and human health. Therefore, the development of efficient, economical and environmentally friendly domestic sewage treatment technologies is of great significance.

[0003] Wastewater with a pH of 7.0-7.5 is filtered through a mechanical screen and introduced into the hydrolysis adjustment tank. After hydrolysis treatment, the wastewater flows out of the contact oxidation tank. After partial contact oxidation, the wastewater enters the anoxic tank, secondary aerobic tank, and secondary sedimentation tank, and then overflows from the top of the filtration tank and disinfection tank. The effluent water quality meets and exceeds the national Class A emission standards. In principle, this part of the clean water is preferentially used for landscaping in the summer. The clean water after treatment by the domestic wastewater treatment device contains various impurities, such as suspended matter, colloids, organic matter, and inorganic salts. To ensure the normal operation of the reverse osmosis part of the desalination system, the suspended matter, colloids, and organic matter in the water must be removed first to ensure that the reverse osmosis water meets the requirements. A pretreatment system is added before the domestic wastewater enters the membrane. The biochemical effluent is reacted, coagulated, precipitated and filtered before being sent to the ultrafiltration system. The ultrafiltration water is softened by the water softener to reduce the hardness and then sent to the desalted water reverse osmosis system. The reverse osmosis water is transported to the desalted water tank through EDI electric desalination and is used by downstream users. The ultrafiltration backwash water is discharged to the front end of the pre-sedimentation system for further reaction, precipitation and filtration, and the reverse osmosis concentrated water is treated by the concentrated water RO system and sent to the ultrafiltration water tank. The concentrated water is then concentrated again and sent to the production wastewater MVR zero discharge system.

[0004] In this process system, after domestic sewage is treated, it undergoes pretreatment (triple tank, inclined plate sedimentation tank, multi-media filter) and the water quality undergoes secondary physical purification. However, the water still contains a small amount of organic matter and microorganisms, which can easily clog the ultrafiltration system. The ultrafiltration membrane has a short service life and often requires chemical cleaning. The high-concentration brine produced by desalting water enters the MVR evaporation and crystallization system, causing the COD of the brine in the evaporator to be too high, making it difficult to treat. Summary of the Invention

[0005] Purpose of the utility model: The technical problem to be solved by the utility model is to address the deficiencies of the existing technology and provide a device that uses STRO membrane to treat domestic sewage in polysilicon production plants, reduce the impact of domestic sewage on the desalination system, and shorten the equipment and material replacement cycle.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0007] A STRO membrane desalination device for a polysilicon production plant comprises a multi-stage safety filter, a high-pressure pump, a circulation pump, and a group of STRO membrane filtration modules; the multi-stage safety filter, the high-pressure pump, and the circulation pump are sequentially connected by pipes; the STRO membrane filtration modules are connected by parallel pipes, and wastewater is respectively sent to each STRO membrane filtration module for treatment via the circulation pump.

[0008] Furthermore, the clean water generated by the filtration of each STRO membrane filtration module is collected into the water production tank through a pipeline.

[0009] Furthermore, the concentrated water generated by the filtration of each STRO membrane filtration module is collected into the COD degradation system through a pipeline.

[0010] Furthermore, the multi-stage security filter includes at least a primary security filter and a secondary security filter.

[0011] Furthermore, the filter element of the first-level security filter is 40-25µm.

[0012] Furthermore, the filter element of the secondary security filter is 5 to 0.45 μm.

[0013] Furthermore, a self-cleaning filter is provided at the front end of the multi-stage security filter.

[0014] Furthermore, a multi-media filter is provided at the front end of the self-cleaning filter.

[0015] Furthermore, an inclined plate settler is provided at the front end of the multi-media filter.

[0016] Furthermore, a soft water tank is provided at the front end of the inclined plate settler. Beneficial effects

[0017] The STRO membrane in this new desalination system can tolerate high suspended solids content, is easy to clean and maintain, has low reliance on biological pretreatment, has strong filtration stability, and high operational safety. It has the advantages of small footprint, long service life, and low energy consumption. The concentrated brine produced by filtration enters the pretreatment system for recycling, reducing external discharge and improving water resource utilization. The COD degradation system reduces the COD in the water, reducing the MVR evaporation and crystallization load. The COD of the STRO concentrated water is ≤400mg / L, avoiding the risk of fouling and blockage caused by frequent ultrafiltration cleanings, and reducing the impact of excessively high COD in the concentrated water on the MVR falling film evaporation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0019] Figure 1 It is a schematic diagram of the overall system structure of the device of the utility model.

[0020] Wherein, each reference numeral represents:

[0021] 1-First-level safety filter; 2-Second-level safety filter; 3-High-pressure pump; 4-Circulation pump; 5-STRO membrane filtration module; 6-COD degradation system; 7-Water production tank. DETAILED DESCRIPTION

[0022] The present invention can be better understood according to the following embodiments.

[0023] The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for the understanding and reading of those familiar with this technology. They are not used to limit the conditions for the implementation of the utility model and therefore have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in the utility model without affecting the efficacy and purpose of the utility model. At the same time, terms such as "upper", "lower", "front", "back", and "middle" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the utility model. Changes or adjustments in their relative relationships should also be considered as the scope of the implementation of the utility model without substantially changing the technical content.

[0024] like Figure 1 As shown, the STRO membrane desalination device of the polysilicon production plant includes a multi-stage safety filter, a high-pressure pump 3, a circulation pump 4 and a group of STRO membrane filtration modules 5; the multi-stage safety filter, high-pressure pump 3, and circulation pump 4 are connected in sequence through pipelines; the STRO membrane filtration modules 5 are connected by parallel pipelines, and the sewage is sent to each STRO membrane filtration module 5 for treatment through the circulation pump 4.

[0025] In this embodiment, the molecular weight cutoff of the STRO membrane filtration module 5 is about 500,000. The STRO membrane can effectively intercept all dissolved salts and organic matter with a molecular weight greater than 100, while allowing water molecules to pass through and intercepting substances larger than 0.0001 microns.

[0026] In this embodiment, the clean water generated by the filtration of each STRO membrane filtration module 5 is collected into the water production tank 7 through a pipeline.

[0027] In this embodiment, the concentrated water generated by the filtration of each STRO membrane filtration module 5 is collected into the COD degradation system 6 through a pipeline.

[0028] In this embodiment, the multi-stage security filter at least includes a primary security filter 1 and a secondary security filter 2 .

[0029] In this embodiment, the filter element of the first-level security filter 1 has a thickness of 40-25 μm.

[0030] In this embodiment, the filter element of the secondary security filter 2 has a filter thickness of 5 to 0.45 μm.

[0031] In some embodiments, a self-cleaning filter is further provided at the front end of the multi-stage security filter.

[0032] In some embodiments, a multi-media filter is provided at the front end of the self-cleaning filter.

[0033] In some embodiments, an inclined plate settler is provided at the front end of the multi-media filter.

[0034] In some embodiments, a soft water tank is provided at the front end of the inclined plate settler.

[0035] During operation, sodium carbonate is added to soften the water and reduce the calcium ion content of the incoming water. Inclined plate settlers accelerate sludge settling. A multi-media filter then removes large suspended solids from the wastewater. A self-cleaning filter reduces the amount of grit entering the safety filter, removing suspended solids from the water. A primary safety filter (1) (40µm filter element) and a secondary safety filter (2) (5µm filter element) are added to the front end of the STRO membrane filtration module 5 to remove fine suspended solids, minimizing damage to the high-pressure pump 3 and clogging of the STRO membrane filtration module 5. Antiscaling agents and non-oxidizing biocides are added to reduce scaling and bacterial growth in the STRO membrane filtration module 5, which can affect water quality. The recovery rate reaches 80%. The STRO membrane filtration module 5 features open flow channels and other anti-fouling and clogging features. Currently, the influent CODCr value of the STRO system after pretreatment is 200-400 mg / L, and the TDS is 16,000 mg / L. The water flux through the STRO unit is maintained at 15-17 L / (m²·h) with no significant flux reduction. Circulation pump 4 has a high flow rate and low head, while high-pressure pump 3 has a low flow rate and high head. These two pumps operate in series to achieve high cross-flow and high-pressure operation, resulting in high recovery rates and slow scaling. The STRO concentrate enters COD degradation system 6, which reduces the COD content and reduces the load on the evaporation and crystallization unit. The STRO product water enters product water tank 7.

[0036] This system replaces the traditional ultrafiltration membrane with a STRO membrane. The brine produced by the STRO membrane then passes through a degradation system to reduce the COD content in the brine. Ultrafiltration membrane water produces water with a conductivity of approximately 2000µs / cm and a COD ≥ 500mg / L. STRO membrane water produces water with a conductivity of ≤ 1000µs / cm. The resulting brine then passes through a degradation system to reduce the COD to ≤ 500mg / L, reducing the load on the MVR evaporation system.

[0037] This utility model provides a concept and method for a STRO membrane desalination system for a polysilicon production plant. There are many methods and approaches to implement this technical solution. The above is only a preferred embodiment of the utility model. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the utility model, and such improvements and modifications should also be considered within the scope of protection of the utility model. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. A STRO membrane desalination device for a polysilicon production plant, characterized in that: The invention comprises a multi-stage safety filter, a high-pressure pump (3), a circulation pump (4) and a group of STRO membrane filtration modules (5); the multi-stage safety filter, the high-pressure pump (3) and the circulation pump (4) are connected in sequence through pipelines; each of the STRO membrane filtration modules (5) is connected by parallel pipelines, and sewage is respectively sent to each STRO membrane filtration module (5) for treatment through the circulation pump (4).

2. The polysilicon production plant STRO membrane desalination device according to claim 1, characterized in that: The clean water generated by the filtration of each STRO membrane filtration module (5) is collected into the water production tank (7) through a pipeline.

3. The polysilicon production plant STRO membrane desalination device according to claim 1, characterized in that: The concentrated water generated by the filtration of each STRO membrane filtration module (5) is collected through a pipeline to the COD degradation system (6).

4. The polysilicon production plant STRO membrane desalination device according to claim 1, characterized in that: The multi-stage security filter comprises at least a first-stage security filter (1) and a second-stage security filter (2).

5. The polysilicon production plant STRO membrane desalination device according to claim 4, characterized in that: The filter element of the first-level security filter (1) is 40-25µm.

6. The polysilicon production plant STRO membrane desalination device according to claim 4, characterized in that: The filter element of the secondary security filter (2) is 5 to 0.45 μm.

7. The polysilicon production plant STRO membrane desalination device according to claim 1, characterized in that: A self-cleaning filter is also provided at the front end of the multi-stage safety filter.

8. The polysilicon production plant STRO membrane desalination device according to claim 7, characterized in that: A multi-media filter is provided at the front end of the self-cleaning filter.

9. The polysilicon production plant STRO membrane desalination device according to claim 8, characterized in that: The front end of the multi-media filter is provided with an inclined plate settler.

10. The STRO membrane desalination device for a polysilicon production plant according to claim 9, characterized in that: A soft water tank is provided at the front end of the inclined plate settler.

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