Resourceful treatment system for wastewater of thermal power plant

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The wastewater resource utilization system for thermal power plants, utilizing technologies such as ceramic membranes and nanofiltration, has solved the problem of wastewater treatment in thermal power plants, achieving efficient resource utilization and economic benefits, and addressing the issues of suspended solids and heavy metals in the wastewater.

CN223722970UActive Publication Date: 2025-12-26HANGZHOU HUADIAN BANSHAN POWER GENERATION

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Patent Information

Application Number: CN202520012909.2
Authority / Receiving Office: CN · China
Patent Type: Utility models(China)
Current Assignee / Owner
Filing Date: 2025-01-03
Publication Date: 2025-12-26
Estimated Expiration: 2035-01-03

AI Technical Summary

Technical Problem

Wastewater from thermal power plants contains suspended solids and heavy metals, with a pH value of 5-6, making it highly polluting and difficult to treat and utilize effectively using existing technologies.

Method used

A wastewater resource utilization system for thermal power plants is adopted, including heat exchangers, pre-sedimentation tanks, ceramic membrane devices, nanofiltration devices, high-pressure nanofiltration devices, cryogenic crystallization devices, and bipolar membrane devices. Magnesium ions and calcium ions are separated through chemical reactions and membrane separation technology, and chloride ions and sulfate ions are recovered to achieve resource utilization.

Benefits of technology

It achieves the reuse of more than 90% of the water in the wastewater from thermal power plants, and makes resource-based use of Mg2+, Ca2+, Cl-, and SO42- ions, reducing the amount of NaOH and HCl added, lowering treatment costs, and reducing the system's footprint, thus having economic and social benefits.

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Abstract

The utility model provides a resourceful treatment system for wastewater of a thermal power plant. The resourceful treatment system comprises a heat exchanger, a pre-sedimentation tank, a first reaction tank, a first concentration tank, a first ceramic membrane device, a second reaction tank, a second concentration tank, a second ceramic membrane device, a nanofiltration device, a high-pressure nanofiltration device, a freezing crystallization device and a hot melting device which are connected in sequence. Through the chemical reaction, the first ceramic membrane device, the second ceramic membrane device, the nanofiltration device and the high-pressure nanofiltration device, the reverse osmosis device and the bipolar membrane device, more than 90% of water in the wastewater of the thermal power plant can be recycled, and Mg < 2 + > ions, Ca < 2 + > ions, Cl <-> ions and SO4 < 2-> ions in the wastewater can be recycled; the strong brine is treated by the bipolar membrane device to obtain NaOH and HCl, so that the dosage of NaOH and HCl can be reduced, and the treatment cost is further reduced; the concentration effect of Mg (OH) 2 and calcium oxalate can be improved through the first ceramic membrane device and the second ceramic membrane device, a sedimentation tank is not needed, and the occupied area of the system is reduced.

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Description

TECHNICAL FIELD

[0001] The utility model belongs to wastewater treatment technical field especially, it is a kind of resource processing system of thermal power plant wastewater. BACKGROUND

[0002] Thermal power plant can produce wastewater, the pH value of wastewater is 5~6, simultaneously contains a large amount of suspended matter (gypsum particles, SO2, Al and iron hydroxide) and As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Sn, Zn and other heavy metal elements.Because water quality is special, pollution is strong, therefore, thermal power plant wastewater must be discharged after being treated separately, otherwise it can cause great pollution to environment.Therefore, to thermal power plant wastewater for depth processing, realize the resource of thermal power plant wastewater has become the new challenge that coal-fired power plant planning and design, environmental protection upgrading and reconstruction work face. CONTENT

[0003] The utility model is to provide a kind of resource processing system of thermal power plant wastewater, to separate magnesium ion, calcium ion, recover chloride ion, sulfate ion.

[0004] Therefore, the above-mentioned purpose of the utility model is realized by the following technical scheme:

[0005] A kind of resource processing system of thermal power plant wastewater, it is characterized by: the system includes heat exchanger, pre-sedimentation tank, first reaction pool, first concentration tank, first ceramic membrane device, second reaction pool, second concentration tank, second ceramic membrane device, nanofiltration device, high-pressure nanofiltration device, freeze crystallization device and hot melting device connected in sequence;

[0006] The pre-sedimentation tank is communicated with the heat source side outlet of heat exchanger, the first reaction pool is communicated with the supernatant outlet of pre-sedimentation tank, the first concentration tank is communicated with the liquid outlet of first reaction pool, the inlet of first ceramic membrane device is communicated with the feed liquid outlet of first concentration tank, the second reaction pool is communicated with the water production outlet of first ceramic membrane device, and the concentrated water outlet of first ceramic membrane device is communicated to first concentration tank;The second concentration tank is communicated with the liquid outlet of second reaction pool, the inlet of second ceramic membrane device is communicated with the feed liquid outlet of second concentration tank, and the concentrated water outlet of second ceramic membrane is communicated to second concentration tank;The inlet of nanofiltration device is communicated with the water production outlet of second ceramic membrane device, the inlet of high-pressure nanofiltration device is communicated with the concentrated liquid outlet of nanofiltration device, the inlet of freeze crystallization device is communicated with the concentrated liquid outlet of high-pressure nanofiltration device, and the inlet of hot melting device is communicated with the freeze crystallization outlet of freeze crystallization device;

[0007] The mother liquor outlet of the freezing crystallization device is communicated to the cold source side inlet of the heat exchanger, and the cold source side outlet of the heat exchanger is communicated to the inlet of the nanofiltration device;

[0008] The concentrated liquid outlet of the nanofiltration device is also communicated to the inlet of the reverse osmosis device, the concentrated liquid outlet of the reverse osmosis device is respectively communicated to the inlet of the evaporation device and the inlet of the bipolar membrane device, the alkali liquid outlet of the bipolar membrane device is communicated to the first reaction tank, and the acid liquid outlet of the bipolar membrane device is communicated to the inlet of the nanofiltration device.

[0009] In addition to the above technical solutions, the utility model also can adopt or adopt the following technical solutions in combination:

[0010] As a preferred technical solution of the utility model: the system further includes a first filter press, and the first filter press is communicated to the bottom of the first concentration tank.

[0011] As a preferred technical solution of the utility model: the system further includes a second filter press, and the second filter press is communicated to the bottom of the second concentration tank.

[0012] As a preferred technical solution of the utility model: the water production outlet of the high-pressure nanofiltration device is communicated to the inlet of the reverse osmosis device.

[0013] As a preferred technical solution of the utility model: the nanofiltration membrane in the nanofiltration device is a tubular nanofiltration membrane or a disc tube nanofiltration membrane, the interception rate of the nanofiltration membrane to divalent ions such as calcium ions and sulfate ions is above 99%, and the concentration of sodium sulfate in the concentrated liquid of the nanofiltration device is 50000-90000 mg / L.

[0014] As a preferred technical solution of the utility model: the nanofiltration membrane in the high-pressure nanofiltration device is a tubular nanofiltration membrane or a disc tube nanofiltration membrane, the interception rate of the nanofiltration membrane to divalent ions such as calcium ions and sulfate ions is above 99%, and the concentration of sodium sulfate in the concentrated liquid of the high-pressure nanofiltration device is 120000-150000 mg / L.

[0015] As a preferred technical solution of the utility model: a sodium hydroxide adding port is arranged on the communication pipeline between the pre-sedimentation tank and the first reaction tank.

[0016] As a preferred technical solution of the utility model: an oxalic acid adding port is arranged on the communication pipeline between the first ceramic membrane device and the second reaction tank.

[0017] As a preferred technical solution of the utility model: the brine outlet of the bipolar membrane device is communicated to the inlet of the evaporation device.

[0018] The utility model provides a kind of resource processing system of thermal power plant wastewater, with following beneficial effects:

[0019] 1), through "chemical reaction + ceramic membrane system (first ceramic membrane device, second ceramic membrane device) + nanofiltration system (nanofiltration device and high pressure nanofiltration device) + reverse osmosis device + bipolar membrane device", more than 90% of the water in the waste water of thermal power plant can be recycled, and Mg 2+ ions, Ca 2+ ions, Cl - ions and SO4 2- ions can be recycled and utilized as resources in waste water;

[0020] 2), the concentrated brine is treated by the bipolar membrane device to obtain NaOH and HCl, so that the dosing amount of NaOH and HCl can be reduced, and the treatment cost can be further reduced;

[0021] 3), the ceramic membrane system (first ceramic membrane device, second ceramic membrane device) can improve the concentration effect of Mg(OH)2 and calcium oxalate, so that the sedimentation tank is not needed, and the land area occupied by the system is reduced;

[0022] 4), the resource treatment system for waste water of thermal power plant provided by the utility model has economic benefit and social benefit when treating waste water of thermal power plant, and has research and popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The figure of the resource treatment system for waste water of thermal power plant provided by the utility model is shown. DETAILED DESCRIPTION

[0024] The utility model is further described in detail with reference to the drawings and specific embodiments.

[0025] A resource treatment system for waste water of thermal power plant, comprising heat exchangers, a pre-sedimentation tank, a first reaction tank, a first concentration tank, a first ceramic membrane device, a second reaction tank, a second concentration tank, a second ceramic membrane device, a nanofiltration device, a high pressure nanofiltration device, a refrigeration crystallization device and a hot melting device connected in sequence;

[0026] The pre-sedimentation tank is connected to the heat source side outlet of the heat exchanger, the first reaction tank is connected to the supernatant outlet of the pre-sedimentation tank, the first concentration tank is connected to the liquid outlet of the first reaction tank, the inlet of the first ceramic membrane device is connected to the feed liquid outlet of the first concentration tank, the second reaction tank is connected to the water outlet of the first ceramic membrane device, and the concentrated water outlet of the first ceramic membrane device is connected to the first concentration tank; the second concentration tank is connected to the liquid outlet of the second reaction tank, the inlet of the second ceramic membrane device is connected to the feed liquid outlet of the second concentration tank, and the concentrated water outlet of the second ceramic membrane is connected to the second concentration tank; the inlet of the nanofiltration device is connected to the water outlet of the second ceramic membrane device, the inlet of the high-pressure nanofiltration device is connected to the concentrated liquid outlet of the nanofiltration device, the inlet of the freeze crystallization device is connected to the concentrated liquid outlet of the high-pressure nanofiltration device, and the inlet of the hot melting device is connected to the freeze crystallization outlet of the freeze crystallization device;

[0027] The mother liquor outlet of the freeze crystallization device is connected to the cold source side inlet of the heat exchanger, and the cold source side outlet of the heat exchanger is connected to the inlet of the nanofiltration device.

[0028] The concentrated liquid outlet of the nanofiltration device is also connected to the inlet of the reverse osmosis device, the concentrated liquid outlet of the reverse osmosis device is connected to the inlet of the evaporation device and the inlet of the bipolar membrane device respectively, the alkali liquid outlet of the bipolar membrane device is connected to the first reaction tank, and the acid liquid outlet of the bipolar membrane device is connected to the inlet of the nanofiltration device.

[0029] The system further comprises a first filter press connected to the bottom of the first concentration tank.

[0030] The system further comprises a second filter press connected to the bottom of the second concentration tank.

[0031] The water outlet of the high-pressure nanofiltration device is connected to the inlet of the reverse osmosis device.

[0032] The nanofiltration membrane in the nanofiltration device is a tubular nanofiltration membrane or a disc-tube nanofiltration membrane, the interception rate of the nanofiltration membrane to divalent ions such as calcium ions and sulfate ions is above 99%, and the concentration of sodium sulfate in the concentrated liquid of the nanofiltration device is 50,000-90,000 mg / L.

[0033] The nanofiltration membrane in the high-pressure nanofiltration device is a tubular nanofiltration membrane or a disc-tube nanofiltration membrane, the interception rate of the nanofiltration membrane to divalent ions such as calcium ions and sulfate ions is above 99%, and the concentration of sodium sulfate in the concentrated liquid of the high-pressure nanofiltration device is 120,000-150,000 mg / L.

[0034] A sodium hydroxide adding port is arranged on the connecting pipeline between the pre-sedimentation tank and the first reaction tank.

[0035] An oxalic acid adding port is arranged on the connecting pipeline between the first ceramic membrane device and the second reaction tank.

[0036] The saltwater outlet of the bipolar membrane device is communicated to the inlet of the evaporation device.

[0037] Specifically, the resource processing system of the thermal power plant wastewater operates in the following manner:

[0038] 1) The thermal power plant wastewater is treated by a triple-tank, and then enters a pre-sedimentation tank to obtain a sediment at the bottom and supernatant at the top; the triple-tank includes a neutralization tank, a reaction tank and a flocculation tank; after the wastewater enters the neutralization tank, the pH value is adjusted by adding lime milk, so that the pH value of the wastewater is 9-10, at which time most of the heavy metal ions form hydroxide precipitates. Part of the unprecipitated heavy metal ions enter the reaction tank with the wastewater, and by adding an organic sulfur solution to the reaction tank, the part of the heavy metal ions form slightly soluble precipitates. At the same time, a flocculant is added to make the suspended solids and the precipitates in the wastewater form larger particles of flocculation. Subsequently, the wastewater enters the flocculation tank, and by adding a coagulant aid, the flocculation formed above is accelerated to settle. After the triple-tank treatment, the wastewater enters the pre-sedimentation tank for mud-water separation.

[0039] 2) The supernatant obtained from the pre-sedimentation tank is overflowed to the first reaction tank after adding NaOH, and the supernatant and NaOH are fully reacted in the first reaction tank;

[0040] 3) The effluent from the first reaction tank enters the first concentration tank, and the liquid in the first concentration tank is transported into the first ceramic membrane device for filtration treatment by a large-flow circulating pump, the Mg(OH)2 precipitate formed by the reaction is intercepted and returned to the first concentration tank, the Mg(OH)2 concentration continuously increases, and when it reaches a certain concentration, it is transported to the first filter press for filtration to obtain magnesium hydroxide;

[0041] 4) The water produced by the first ceramic membrane device enters the second reaction tank through a pipeline, a dosing port for adding oxalic acid is opened on the pipeline, and a certain stirring treatment is performed at a certain speed, and after a certain reaction time, the effluent from the second reaction tank enters the second concentration tank, and the liquid in the second concentration tank is transported into the second ceramic membrane device for filtration treatment by a large-flow circulating pump, the calcium oxalate precipitate formed by the reaction is intercepted and returned to the second concentration tank, the calcium oxalate concentration continuously increases, and when it reaches a certain concentration, it is transported to the second filter press for filtration to obtain calcium oxalate;

[0042] 5) The water produced by the second ceramic membrane device enters the nanofiltration device for filtration treatment to obtain dialysate and concentrated liquid;

[0043] 6), the concentrated liquid treated by the nanofiltration device enters a high-pressure nanofiltration device to be concentrated again, to obtain dialysate and concentrated liquid. The concentrated liquid is discharged into a freeze crystallization device to be freeze crystallized (the freeze crystallization crystallization temperature is 0-5℃), to obtain sodium sulfate decahydrate, and then enters a hot melting device to be hot melted to obtain anhydrous sodium sulfate, and the mother liquor of the freeze crystallization device and the raw water are mixed with the product water of the second ceramic membrane device after heat exchange by a heat exchanger to enter the nanofiltration device;

[0044] 7), the dialysate treated by the nanofiltration device enters a reverse osmosis device to be concentrated, to obtain dialysate and concentrated liquid (the concentrated liquid of the reverse osmosis device is concentrated brine with a salt content higher than 10%), and the concentrated liquid of the nanofiltration device is divided into two paths, one path enters an evaporation device to be evaporated and crystallized to obtain sodium chloride crystalline salt, and the other path enters a bipolar membrane device to obtain hydrochloric acid, sodium hydroxide and brine, the hydrochloric acid is used for pH adjustment before nanofiltration, the sodium hydroxide is used for adjusting the pH of the first reaction tank, and the brine and the concentrated water of the reverse osmosis device are mixed to enter the evaporation device. The dialysate (product water) of the reverse osmosis device is used as recycled water.

[0045] The concentration of the HCl solution treated by the bipolar membrane device is 1.5-2.5mol / L, and the concentration of the NaOH solution is 1.5-3.2mol / L.

[0046] The above specific embodiments are used to explain and illustrate the present application, and are only preferred embodiments of the present application, rather than limiting the present application, and any modification, equivalent replacement, improvement, etc. made to the present application within the spirit and protection scope of the claims of the present application, all fall within the protection scope of the present application.

Claims

1. A system for resourceful treatment of waste water from a thermal power plant, characterized in that: The system comprises a heat exchanger, a pre-sedimentation tank, a first reaction tank, a first concentration tank, a first ceramic membrane device, a second reaction tank, a second concentration tank, a second ceramic membrane device, a nanofiltration device, a high-pressure nanofiltration device, a freeze crystallization device and a hot melting device connected in sequence. The pre-sedimentation tank is connected to the heat source side outlet of the heat exchanger, the first reaction tank is connected to the supernatant outlet of the pre-sedimentation tank, the first concentration tank is connected to the liquid outlet of the first reaction tank, the inlet of the first ceramic membrane device is connected to the feed liquid outlet of the first concentration tank, the second reaction tank is connected to the water outlet of the first ceramic membrane device, and the concentrated water outlet of the first ceramic membrane device is connected to the first concentration tank. The concentrated liquid outlet of the nanofiltration device is also connected to the inlet of the reverse osmosis device, the concentrated liquid outlet of the reverse osmosis device is connected to the inlet of the evaporation device and the inlet of the bipolar membrane device respectively, the alkali liquid outlet of the bipolar membrane device is connected to the first reaction tank, and the acid liquid outlet of the bipolar membrane device is connected to the inlet of the nanofiltration device. The system further comprises a first filter press connected to the bottom of the first concentration tank.

2. The system for resource recovery of thermal power plant wastewater according to claim 1, characterized in that: The system further comprises a second filter press connected to the bottom of the second concentration tank.

3. The system for resource recovery of thermal power plant wastewater according to claim 1, characterized in that: The water outlet of the high-pressure nanofiltration device is connected to the inlet of the reverse osmosis device.

4. The thermal power plant wastewater valorization system according to claim 1, characterized in that: The nanofiltration membrane in the nanofiltration device is a tubular nanofiltration membrane or a disc-tube nanofiltration membrane.

5. The thermal power plant wastewater valorization system according to claim 1, characterized in that: The nanofiltration membrane in the high-pressure nanofiltration device is a tubular nanofiltration membrane or a disc-tube nanofiltration membrane.

6. The thermal power plant wastewater valorization system according to claim 1, characterized in that: A sodium hydroxide adding port is arranged on the connecting pipeline between the pre-sedimentation tank and the first reaction tank.

7. The thermal power plant wastewater valorization system according to claim 1, characterized in that: An oxalic acid adding port is arranged on the connecting pipeline between the first ceramic membrane device and the second reaction tank.

8. The system for resource recovery of thermal power plant wastewater according to claim 1, characterized in that: The brine outlet of the bipolar membrane device is connected to the inlet of the evaporation device.

9. The thermal power plant wastewater valorization system according to claim 1, characterized in that: