Power plant wastewater recycling-waste heat recovery coupling system

Abstract

The utility model provides a waste water recycling-waste heat recovery coupling system for a power plant. The waste water recycling-waste heat recovery coupling system comprises a membrane distillation raw water tank, a membrane distillation circulating pump, a first heat exchanger, a membrane distillation device, a second heat exchanger, a vacuum tank, a condensate water tank and a vacuum pump, according to the power plant wastewater recycling-waste heat recovery coupling system, waste heat water of a thermal power plant serves as a heat source and exchanges heat with wastewater of the thermal power plant through a first heat exchanger, then the heated wastewater of the thermal power plant is concentrated through a membrane distillation device, the concentrated wastewater is circulated to a membrane distillation raw water tank, and after the requirement for the emission concentration is met, waste heat is recycled. And the permeate liquid of the membrane distillation device passes through the second heat exchanger and then enters the vacuum tank to be condensed, and condensate water is collected through the condensate water tank. The device can improve the concentration effect of the waste water of the thermal power plant, and can reduce the occupied area and civil engineering investment of the system compared with the conventional common reverse osmosis membrane system.

Description

TECHNICAL FIELD

[0001] The utility model belongs to power plant wastewater treatment technical field especially, be related to a power plant wastewater resource - waste heat recovery coupling system. BACKGROUND

[0002] Wastewater resource of thermal power plant gradually becomes the development trend of thermal power plant wastewater treatment.Wastewater resource mainly is to take effective measures to realize the continuous recycling of water resources in thermal power plant, try to reduce the wastewater of different degree of pollution to outside, the water into the power plant can finally in the form of steam into the atmosphere, or realize the closed treatment with proper form.

[0003] ‌Power plant waste heat utilization refers to recycling the waste heat generated in the process of power generation through technical means, to improve energy utilization efficiency, reduce energy waste and reduce operating costs.Power plant waste heat mainly includes heat generated by boiler flue gas, cooling medium, wastewater, etc.If these waste heat is effectively utilized, not only can improve the energy utilization efficiency of power plant, but also can reduce greenhouse gas emissions, in line with the requirements of energy saving and emission reduction.Through waste heat recovery and utilization, the energy utilization efficiency of power plant can be improved, fuel consumption can be reduced, and operating costs can be reduced.For example, the flue gas waste heat recovery system can reduce the boiler exhaust loss and improve the thermal efficiency, and the boiler thermal efficiency can be improved by about 1% for every 10℃ reduction in exhaust gas temperature.Through waste heat recovery and utilization, greenhouse gas emissions can be reduced, and carbon dioxide and other pollutants can be reduced, in line with the national energy saving and emission reduction policy requirements, and the social image and competitiveness of enterprises can be improved.‌

[0004] Membrane distillation (MD) is a membrane separation process driven by the vapor pressure difference across a hydrophobic microporous membrane. It is a combination of membrane technology and distillation process. The volatile components in the feed solution permeate through the membrane pores in the form of vapor, thus achieving the separation purpose. The organic membrane distillation technology has many advantages: compared with multi-effect evaporation and other evaporation processes, the feed temperature of the organic membrane distillation is relatively low, and low-grade energy such as solar energy, geothermal energy and waste heat of factories can be used to reduce operating costs; the organic membrane distillation equipment is simple, the operating conditions are mild, and the flexibility of using high-efficiency small membrane components to form large-scale production system is realized, and the equipment investment is low. Compared with high-pressure reverse osmosis and other processes, the operating pressure of the organic membrane distillation is low, the operation is convenient, and it can handle very high concentration of aqueous solution, can concentrate the solution to supersaturated state, realize direct separation of crystalline product from the solution, and can realize high desalination rate. It has good potential application prospect in material concentration, desalination and zero emission. In the organic membrane distillation process of non-volatile solute aqueous solution, because only water vapor can permeate through the membrane pores, the distillation liquid is very pure, and it is expected to become an effective means for large-scale and low-cost preparation of ultrapure water. The hollow fiber structure of the hydrophobic PTFE membrane has very high specific surface area and provides mass transfer interface for two-phase mass transfer. Because PTFE material has good hydrophobicity and chemical stability, compared with other membrane materials such as PP or PVDF, the service life of PTFE membrane is long, and the running performance is stable. Practical new type content

[0005] The utility model discloses a kind of power plant wastewater resourceization-heat recovery coupling systems.

[0006] To this end, the above-mentioned purpose of the utility model is realized by the following technical solutions.

[0007] A power plant wastewater resourceization-heat recovery coupling system includes a membrane distillation raw water tank, a membrane distillation circulating pump, a first heat exchanger, a membrane distillation device, a second heat exchanger, a vacuum tank, a condensate tank, and a vacuum pump.

[0008] The water inlet of the membrane distillation raw water tank is connected to the water outlet of the security filter. The water outlet of the membrane distillation raw water tank is connected to the cold source side inlet of the first heat exchanger through the membrane distillation circulating pump. The cold source side outlet of the first heat exchanger is connected to the inlet of the membrane distillation device. The heat source side inlet of the first heat exchanger is connected to the waste heat water of the thermal power plant.

[0009] The concentrated liquid outlet of the membrane distillation device is connected to the raw water tank, and an external discharge pipeline is provided on the connecting pipeline.

[0010] The permeate outlet of the membrane distillation device is communicated with the heat source side inlet of the second heat exchanger, the heat source side outlet of the second heat exchanger is communicated with the inlet of the vacuum tank, and the cold source side of the second heat exchanger is communicated with cooling water; the vacuum tank is provided below with a condensate tank, the condensate tank is communicated with the bottom of the vacuum tank, and the vacuum tank is communicated with a vacuum pump.

[0011] In addition to the above technical solutions, the utility model also can adopt or adopt the following technical solutions in combination:

[0012] As a preferred technical solution of the utility model: the system is also equipped with hot water tank, the hot water tank is equipped with electric heating system, the hot water tank is communicated with the heat source side inlet of the first heat exchanger through hot water pump.

[0013] As a preferred technical solution of the utility model: the heat source outlet of the first heat exchanger is communicated with the hot water tank.

[0014] As a preferred technical solution of the utility model: the condensate tank is communicated with the vacuum pump.

[0015] As a preferred technical solution of the utility model: the filter precision of the security filter is 5-10 microns.

[0016] As a preferred technical solution of the utility model: the first heat exchanger is plate heat exchanger or shell and tube heat exchanger.

[0017] The second heat exchanger is plate heat exchanger or shell and tube heat exchanger.

[0018] As a preferred technical solution of the utility model: the membrane assembly of the membrane distillation device is organic hydrophobic microporous filter membrane of PTFE material.

[0019] As a preferred technical solution of the utility model: the membrane assembly of the membrane distillation device is hollow fiber type.

[0020] As a preferred technical solution of the utility model: the nominal pore size of the membrane assembly of the membrane distillation device is 40-50 nm.

[0021] The utility model provides a kind of power plant wastewater resourceization- waste heat recovery coupling system, including membrane distillation raw water tank, membrane distillation circulating pump, first heat exchanger, membrane distillation device, second heat exchanger, vacuum tank, condensate tank and vacuum pump;The power plant wastewater resourceization- waste heat recovery coupling system with thermal power plant waste heat water as heat source is exchanged with thermal power plant wastewater by first heat exchanger, then the thermal power plant wastewater after heating is concentrated by membrane distillation device, and the wastewater after concentration is circulated to membrane distillation raw water tank, after meeting the concentration requirement of external discharge, switch to external discharge pipeline, and the permeate of membrane distillation device enters vacuum tank after second heat exchanger and condenses, and condensate is collected by condensate tank, and specifically, the utility model has the following beneficial effects:

[0022] 1), by setting membrane distillation device, more than 90% of water in thermal power plant wastewater can be reused, and waste heat resource in thermal power plant can be also recycled;Thermal power plant wastewater treatment process can be shortened, additional energy consumption in other process operation can be reduced, treatment cost can be reduced, and the stability of system operation is improved;

[0023] 2), by setting membrane distillation device, vacuum condensing equipment can be equipped, and high-energy evaporation crystallization treatment is not needed;

[0024] 3), the utility model can improve the concentration effect of thermal power plant wastewater, and compared with the commonly used reverse osmosis membrane system, the land area of system and civil engineering investment can be reduced. DRAWINGS

[0025] Figure 1 The utility model provides the connecting diagram of power plant wastewater resourceization- waste heat recovery coupling system;

[0026] In the drawing: 101-membrane distillation raw water tank;201-membrane distillation circulating pump;202-membrane distillation device;301-first heat exchanger;302-second heat exchanger;401-hot water tank;402-hot water pump;501-vacuum tank;502-condensate tank;503-vacuum pump. DETAILED DESCRIPTION

[0027] The application is further described in detail with reference to the drawings and specific embodiments.

[0028] A kind of power plant wastewater resourceization- waste heat recovery coupling system, including membrane distillation raw water tank 101, membrane distillation circulating pump 201, first heat exchanger 301, membrane distillation device 202, second heat exchanger 302, vacuum tank 501, condensate tank 502 and vacuum pump 503;

[0029] The water inlet of the membrane distillation raw water tank 101 is communicated with the water outlet of the security filter, the water outlet of the membrane distillation raw water tank 101 is communicated to the cold source side inlet of the first heat exchanger 301 through the membrane distillation circulating pump 201, and the cold source side outlet of the first heat exchanger 301 is communicated with the inlet of the membrane distillation device 202; the heat source side inlet of the first heat exchanger 301 is connected to the waste heat water of the thermal power plant;

[0030] The concentrated liquid outlet of the membrane distillation device 202 is communicated with the raw water tank, and an external discharge pipeline is arranged on the communication pipeline, when the concentration of the circulating backflow waste water reaches a preset TDS, the circulating pipeline is closed, the external discharge pipeline is opened, and the concentrated waste water is discharged into a rear-end treatment system for deeper waste water treatment;

[0031] The permeated liquid outlet of the membrane distillation device 202 is communicated with the heat source side inlet of the second heat exchanger 302, the heat source side outlet of the second heat exchanger 302 is communicated with the inlet of the vacuum tank 501, and the cold source side of the second heat exchanger 302 is connected to cooling water; the vacuum tank 501 is provided below with a condensate tank 502, the condensate tank 502 is communicated with the bottom of the vacuum tank 501, and the vacuum tank 501 is communicated with a vacuum pump 503. When the water level in the condensate tank 502 reaches a set value, the condensate tank 502 is discharged.

[0032] The system is also provided with a hot water tank 401, the hot water tank 401 is provided with an electric heating system (for example, in the form of an electric heating rod), and the hot water tank 401 is communicated with the heat source side inlet of the first heat exchanger 301 through a hot water pump 402. The heat source outlet of the first heat exchanger 301 is communicated with the hot water tank 401. The purpose of the heating water tank and the electric heating system is to improve the treatment efficiency of the membrane distillation device and avoid insufficient waste heat grade of the waste heat water of the thermal power plant.

[0033] The condensate tank 502 is communicated with the vacuum pump 503.

[0034] The filtering precision of the security filter is 5-10 microns.

[0035] The first heat exchanger 301 is a plate heat exchanger; and the second heat exchanger 302 is a plate heat exchanger.

[0036] The membrane assembly of the membrane distillation device 202 is an organic hydrophobic microporous filter membrane made of PTFE material. The membrane assembly of the membrane distillation device 202 is in a hollow fiber type, so that it has the ability to resist concentration polarization and the ability to resist fouling. The nominal pore size of the membrane assembly of the membrane distillation device 202 is 40-50 nm.

[0037] 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 into the protection scope of the present application.

Claims

1. A power plant wastewater resource recovery- waste heat recovery coupled system, characterized in that: The system comprises a membrane distillation raw water tank, a membrane distillation circulating pump, a first heat exchanger, a membrane distillation device, a second heat exchanger, a vacuum tank, a condensate tank and a vacuum pump. The water inlet of the membrane distillation raw water tank is connected with the water outlet of the security filter, the water outlet of the membrane distillation raw water tank is connected to the cold source side inlet of the first heat exchanger through the membrane distillation circulating pump, and the cold source side outlet of the first heat exchanger is connected with the inlet of the membrane distillation device; the heat source side inlet of the first heat exchanger is connected with the waste heat water of the thermal power plant. The concentrated liquid outlet of the membrane distillation device is connected with the raw water tank, and an external discharge pipeline is arranged on the connecting pipeline. The permeate liquid outlet of the membrane distillation device is connected with the heat source side inlet of the second heat exchanger, the heat source side outlet of the second heat exchanger is connected with the inlet of the vacuum tank, and the cold source side of the second heat exchanger is connected with cooling water; the vacuum tank is provided below the condensate tank, the condensate tank is connected with the bottom of the vacuum tank, and the vacuum tank is connected with the vacuum pump.

2. The system of claim 1, wherein: The system is also provided with a hot water tank, the hot water tank is provided with an electric heating system, and the hot water tank is connected with the heat source side inlet of the first heat exchanger through a hot water pump.

3. The system of claim 2, wherein: The heat source outlet of the first heat exchanger is connected with the hot water tank.

4. The system of claim 1, wherein: The condensate tank is connected with the vacuum pump.

5. The system of claim 1, wherein: The security filter has a filtering precision of 5-10 μm.

6. The system of claim 1, wherein: The first heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger. The second heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger.

7. The system of claim 1, wherein: The membrane assembly of the membrane distillation device is an organic hydrophobic microporous filter membrane made of PTFE.

8. The system of claim 1 or 7, wherein: The membrane assembly of the membrane distillation device is a hollow fiber.

9. The system of claim 8, wherein: The nominal pore size of the membrane assembly of the membrane distillation device is 40-50 nm.

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