Treatment system for heating raw water by using waste heat

Abstract

The invention provides a treatment system for heating raw water by waste heat, which comprises a raw water tank, a primary filtration module, a primary filtration tank, a heat exchanger and an ultrafiltration device which are sequentially connected through a pipeline, a cold end medium and a hot end medium which exchange heat with each other are arranged in the heat exchanger, the cold end medium is water subjected to primary filtration treatment in the primary filtration tank, and the hot end medium is water subjected to secondary filtration treatment in the primary filtration tank. And the hot end medium is desulfurization slurry desulfurized by a desulfurizing tower or cooling water used for cooling steam in a steam turbine condenser. The cold end medium absorbs the heat of the hot end medium and then is conveyed to the backwater treatment system again, so that the temperature requirement of the ultrafiltration device can be met. And the heat end medium returns to the heat source after heat exchange and absorbs heat in the heat source again, so that cyclic utilization of waste heat energy is realized. The water treatment system provided by the invention not only has an excellent water filtering effect, but also can effectively recycle and utilize heat, and compared with the prior art, a large amount of energy can be saved.

Description

Technical Field

[0001] The present invention relates to a water treatment system, specifically a treatment system that uses waste heat to heat raw water. Background Art

[0002] Ultrafiltration devices are important treatment equipment in power plant water treatment systems and can remove most of the organic matter and suspended solids in water. Its working principle is based on physical barrier. The pore size of the ultrafiltration membrane is generally between 0.01 and 0.1 microns. Under a specific pressure, water molecules and small molecule substances can pass through the membrane, while larger particles and molecules (such as bacteria, viruses, suspended solids, and macromolecular organic matter) are intercepted. This technology is suitable for operation at room temperature, especially suitable for the separation of heat-sensitive substances, and has good temperature resistance, acid and alkali resistance, and oxidation resistance. Due to the high efficiency, low energy consumption, and small floor area of ultrafiltration membrane technology, it plays an important role in power plant water treatment systems, helping to improve water quality and reduce operating costs.

[0003] The operating efficiency of ultrafiltration devices is closely related to the inlet water temperature. The higher the inlet water temperature, the greater the water production of the ultrafiltration membrane. Research shows that for every 1°C decrease in the inlet water temperature, the viscosity of water will increase by about 3%, which will increase the resistance to passing through the membrane and lead to a decrease in membrane flux. Therefore, a lower inlet water temperature will reduce the number of water molecules passing through the membrane and decrease the water production. In winter, early spring, or areas with low water temperatures, in order to maintain stable equipment performance, improve water treatment efficiency, and achieve economic operation, it is necessary to heat the raw water at the inlet of the ultrafiltration membrane to 20°C to 27°C through external heating.

[0004] Currently, raw water heating technology usually uses steam to transfer heat to low-temperature raw water through a plate heat exchanger, thereby increasing the inlet water temperature and water production of the ultrafiltration device. However, this heating method requires a certain amount of steam consumption, which will increase the energy consumption of the power plant and reduce the unit efficiency. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a treatment system that uses waste heat to heat raw water, which is characterized in that it includes a raw water tank, a primary filtration module, a primary filtration tank, a heat exchange module, an ultrafiltration device, and a pump body module connected in sequence through pipelines. The pump body module includes multiple pump bodies connected to various parts of the pipeline, and the liquid in the raw water tank is driven by the pump bodies to move directionally;

[0006] The heat exchange module includes a heat exchanger and a waste heat source. The heat exchanger includes a cold end and a hot end for exchanging heat; the waste heat outlet of the waste heat source is connected to the hot end inlet of the heat exchanger, the hot end outlet of the heat exchanger is connected to the waste heat inlet of the waste heat source, the cold end inlet of the heat exchanger is connected to the liquid outlet of the primary filtration tank, and the cold end outlet of the heat exchanger is connected to the liquid inlet of the ultrafiltration device.

[0007] The waste heat source is the desulfurized slurry after desulfurization in the desulfurization tower or the cooling water used to cool the steam in the steam turbine condenser.

[0008] Further, the heat exchanger is a tubular heat exchanger or a plate heat exchanger.

[0009] Further, when the waste heat source is the desulfurized slurry after desulfurization in the desulfurization tower, the desulfurization tower includes a spray layer at the top and a slurry oxidation layer at the bottom. The hot end outlet of the heat exchanger is connected to the spray layer of the desulfurization tower, and the hot end inlet of the heat exchanger is connected to the slurry oxidation layer of the desulfurization tower.

[0010] Further, a second circulation pipeline is connected to the outside of the desulfurization tower. The two ends of the second circulation pipeline are respectively connected to the spray layer and the slurry oxidation layer, and the hot end outlet of the heat exchanger is connected to the second circulation pipeline.

[0011] Further, the primary filtration module includes a flocculation tank, a sedimentation tank, and a sand filtration tank connected in sequence.

[0012] Further, the flocculation tank is a grid flocculation tank.

[0013] Further, when the waste heat source is the cooling water used to cool the steam in the steam turbine condenser, the cooling water outlet of the condenser is connected to the hot end inlet of the heat exchanger through a pipeline, and the hot end outlet of the heat exchanger is connected to the cooling water inlet of the condenser.

[0014] Further, a cooling tower is connected between the cooling water inlet of the condenser and the hot end outlet of the heat exchanger.

[0015] Further, a self-cleaning filter is connected between the ultrafiltration device and the hot end outlet of the heat exchanger.

[0016] The present invention provides a treatment system for heating raw water using waste heat, including a raw water tank, a primary filtration module, a primary filtration tank, a heat exchanger, and an ultrafiltration device connected in sequence through pipelines. There are a cold end medium and a hot end medium in the heat exchanger that exchange heat with each other. The cold end medium is the water that has undergone primary filtration treatment in the primary filtration tank, and the hot end medium is the desulfurized slurry after desulfurization in the desulfurization tower or the cooling water used to cool the steam in the steam turbine condenser. After the cold end medium absorbs the heat of the hot end medium, it is re-transported back to the water treatment system, which can meet the temperature requirements of the ultrafiltration device. The hot end medium returns to the heat source after heat exchange and absorbs heat again in the heat source, thereby realizing the recycling of waste heat energy. The water treatment system provided by the present invention not only has excellent water filtration effect, but also can effectively recover and utilize heat, and can save a large amount of energy compared with the prior art. Description of the Drawings

[0017] Figure 1It is a schematic connection diagram of Embodiment 1 of a treatment system for heating raw water using waste heat according to the present invention;

[0018] Figure 2 It is a schematic connection diagram of Embodiment 2 of a treatment system for heating raw water using waste heat according to the present invention.

[0019] Reference numerals: raw water tank 1, flocculation tank 2, sedimentation tank 3, sand filter 4, primary filter 5, heat exchanger 6, self-cleaning filter 7, ultrafiltration device 8, desulfurization tower 9, steam turbine 10, condenser 11, deaerator 12, cooling tower 13, raw water pump 14, clean water pump 15, pressure pump 16, slurry return pump 17, slurry transfer pump 18, slurry circulation pump 19, cooling water transfer pump 20, cooling water return pump 21, condensate pump 22. Detailed implementation manners

[0020] Embodiment 1: As Figure 1 shown, a treatment system for heating raw water using waste heat includes a raw water tank 1, a primary filtration module, a primary filter 5, a heat exchange module, an ultrafiltration device 8, and a pump body module composed of multiple pump bodies connected in sequence. Industrial raw water to be treated is pumped from a water source and placed in the raw water tank 1, and then transmitted to the primary filtration module through the raw water pump 14. After most of the large particle solid impurities are filtered out in the primary filtration module, it flows to the primary filter 5, is heated by the heat exchange module, and then the impurity particles and molecules in the liquid are filtered out through the membrane treatment structure in the ultrafiltration device 8 to complete the cleaning of the raw water. The raw water is driven by the pump body module and flows directionally along the above connection direction through each component of the treatment system.

[0021] The heat exchange module includes a heat exchanger 6. The heat exchanger 6 can be a tubular heat exchanger 6 or a plate heat exchanger 6, and heat exchange is achieved through the flowing cold-end medium and hot-end medium. Specifically, the outlet of the primary filter 5 is connected to the cold-end inlet a of the heat exchanger 6 through a pipeline, and the inlet of the ultrafiltration device 8 is connected to the cold-end outlet b of the heat exchanger 6. A clean water pump 15 is connected between the primary filter 5 and the heat exchanger 6. The liquid after primary filtration is transported to the heat exchanger 6 by the clean water pump 15 and serves as the cold-end medium of the heat exchanger 6 to exchange heat with the hot-end medium in the heat exchanger 6, and is heated to the target temperature and then transmitted to the ultrafiltration device 8, thereby improving the membrane filtration effect of the ultrafiltration device 8. Further, a self-cleaning filter 7 is connected between the ultrafiltration device 8 and the heat exchanger 6 to filter the heat-exchanged liquid again before ultrafiltration to enhance the filtration effect.

[0022] The heat exchanged in the present invention comes from waste heat recovery in the industrial production system. One of the objectives of the invention is to construct a recyclable waste heat recovery system, make full use of the waste heat of the production device to provide the heat required by the ultrafiltration device 8, and after the hot-end medium exchanges waste heat, it returns to the production system to continue absorbing heat, and so on in a reciprocating cycle, playing a role in saving energy.

[0023] In Example 1, the production system is a desulfurization system. The hot-end medium comes from the desulfurization slurry of the desulfurization system. The desulfurization system is a conventional device in the field of flue gas treatment and is commonly used for desulfurization treatment of the flue gas discharged from boilers. The desulfurization system includes a spray-type desulfurization tower 9 connected to the boiler. The desulfurization tower 9 includes a spray layer at the top and a slurry oxidation layer at the bottom. The desulfurization slurry contains a desulfurizing agent and is atomized into small droplets by nozzles provided in the spray layer, and contacts and reacts with the boiler flue gas introduced into the desulfurization tower 9 to remove sulfur dioxide on the surface of the flue gas. After part of the desulfurization slurry absorbs the heat of the flue gas, it falls into the slurry oxidation area at the bottom of the desulfurization tower 9.

[0024] A first circulation pipeline and a second circulation pipeline are connected to the outside of the desulfurization tower 9. One ends of the first circulation pipeline and the second circulation pipeline are respectively communicated with the slurry oxidation layer, and circulation pumps are respectively arranged on the first circulation pipeline and the second circulation pipeline to drive the slurry to circulate. The other end of the second circulation pipeline is connected to the spray layer of the desulfurization tower 9. The desulfurization slurry at the bottom is driven by a slurry circulation pump 19, returns to the top through the second circulation pipeline and is then sprayed out through the nozzles. The desulfurizing agent in the slurry can be reused, removing sulfur from the flue gas again and exchanging heat with the flue gas. The other end of the first circulation pipeline is connected to the hot-end inlet c of the heat exchanger 6, and the hot-end outlet d of the heat exchanger 6 is connected to the second circulation pipeline. Part of the slurry at the bottom of the desulfurization tower 9 is introduced into the hot-end inlet c of the heat exchanger 6 through the first circulation pipeline, exchanges heat with the liquid after primary filtration in the heat exchanger 6, and then flows through the hot-end outlet d of the heat exchanger 6 to the second circulation pipeline and returns to the top of the desulfurization tower 9 to participate in the desulfurization process of the flue gas again.

[0025] Specifically, a slurry circulation pump 19 is connected to the second circulation pipeline, sucking slurry from the lower layer of the desulfurization tower 9 to the top layer of the desulfurization tower 9; a slurry transfer pump 18 and a slurry return pump 17 are connected to the first circulation pipeline. The slurry transfer pump 18 is connected between the desulfurization tower 9 and the heat exchanger 6, and the slurry return pump 17 is connected between the heat exchanger 6 and the second circulation pipeline, realizing the directional flow of the slurry through the operation of each pump body.

[0026] In the present invention, the primary filtration module includes a flocculation tank 2, a sedimentation tank 3, and a sand filtration tank 4 connected in sequence. The flocculation tank 2 is connected to the raw water tank 1 through a raw water pump 14. The sand filtration tank 4 is connected to the primary filtration tank 5. The liquid in the raw water tank 1 is sucked by the raw water pump 14, and a flocculant is poured into the flocculation tank 2. The fine suspended substances and colloidal particles in the raw water are aggregated into larger flocs, and then pass through the sedimentation tank 3 to settle and separate the flocs in the raw water; finally, through the sand filtration tank 4, the sand filtration layer removes the remaining fine suspended substances and part of the microorganisms in the water, further improving the water quality after primary filtration.

[0027] Specifically, the flocculation tank 2 can be a stirring flocculation tank, a vortex flocculation tank, etc. In this embodiment, the flocculation tank 2 is preferably a grid flocculation tank 2, which includes a plurality of grid layers arranged on the flocculation tank 2. The raw water passes through the multi-layer grids in sequence. After the water flow fully mixes the fine particles in the raw water with the flocculant, larger flocs are formed. The sedimentation tank 3 is an inclined tube sedimentation tank 3, which is connected to the bottom of the flocculation tank 2 through an inclined pipeline. Due to the action of gravity, the raw water flows into the sedimentation tank 3 from the inclined pipeline after passing through the flocculation tank 2, accelerating the sedimentation of the flocs after flocculation and realizing solid-liquid separation. The separated solids are deposited at the bottom of the sedimentation tank 3, and the liquid flows out from above the sedimentation tank 3. The sand filter tank 4 is a V-shaped sand filter tank 4, which is arranged below the sedimentation tank 3. The water inlet tank of the sand filter tank 4 is connected to the water outlet of the sedimentation tank 3, and the water outlet of the sand filter tank 4 is connected to the water inlet of the primary filter tank 5 through a pipeline. The water flow flows from top to bottom through the sand filter tank 4. When passing through the sand filter layer at the bottom of the sand filter tank 4, suspended solids and colloidal particles in the water are removed. After converging into relatively clean water, it flows through the pipeline to the primary filter tank 5, and finally flows to the ultrafiltration device 8 for ultrafiltration after being heated by the heat exchanger 6.

[0028] Using the system provided in this embodiment to treat raw water, taking the raw water treatment volume of 1600 - 1700 t / h and the operation hours of 3600 h / year as an example, compared with the conventional steam heat exchange method, when the raw water is heated from 6°C to 30°C, the steam consumption can be saved by 47 t / h, and the heat recovered throughout the year is 47.4 GJ.

[0029] Embodiment 2: As Figure 2 shown in the second embodiment provided by the present invention, the raw water tank 1, the primary filtration module, the primary filter tank 5, the heat exchange module, the ultrafiltration device 8 and the pump body module composed of multiple water pumps connected in sequence are the same as those in Embodiment 1. The difference is that the heat source in Embodiment 2 comes from the circulating water of the condenser 11 of the steam turbine 10. The steam turbine 10 is a common thermal energy utilization device that can convert thermal energy into mechanical kinetic energy and is widely used in fields such as power generation and ship propulsion. The heat exchange module includes a steam turbine 10 and a condenser 11 connected to the steam end outlet of the steam turbine 10. The function of the condenser 11 is to condense the steam discharged from the steam turbine 10 into water, maintaining a high vacuum state at the exhaust end of the steam turbine 10, thereby improving the thermal efficiency of the steam turbine 10. A deaerator 12 is connected to the rear side of the condenser 11. After the steam is condensed, it is discharged from the condensate outlet of the condenser 11 through the condensate pump 22 and transported to the deaerator 12 to remove the dissolved oxygen and other non-condensable gases in the condensate.

[0030] The condensation of steam relies on heat exchange with cooling water. The side of the condenser 11 is provided with a cooling water inlet and a cooling water outlet for transmitting the circulating cooling water. The cooling water outlet of the condenser 11 is connected to the hot end inlet c of the heat exchanger 6 through a pipeline, and the hot end outlet d of the heat exchanger 6 is connected to the cooling water inlet of the condenser 11. The cooling water flows reciprocally between the condenser 11 and the heat exchanger 6. First, the cooling water exchanges heat with the steam transmitted from the steam turbine 10. After the temperature is increased, it is transmitted to the hot end inlet c of the heat exchanger 6 through the cooling water outlet, exchanges heat with the raw water after primary filtration, and then returns to the condenser 11 from the cooling water inlet after cooling to continue exchanging heat with the steam in the condenser 11, thus forming the recycling of the cooling water.

[0031] Furthermore, a cooling tower 13 is connected between the cooling water inlet and the hot end outlet d of the heat exchanger 6. The two sides of the cooling tower 13 are respectively connected with a cooling water circulation pump 20 and a cooling water return pump 21 to drive the directional movement of the cooling water through the two pump bodies. The function of the cooling tower 13 is to cool the cooling water after heat exchange in the heat exchanger 6 again and strengthen the cooling effect of the cooling water on the steam after it flows into the condenser 11.

[0032] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A treatment system for heating raw water using waste heat, characterized in that: It comprises a raw water pool (1), a primary filter module, a primary filter pool (5), a heat exchange module, an ultrafiltration device (8) and a pump module which are sequentially connected through pipelines, wherein the pump module comprises a plurality of pump bodies connected to various locations of the pipelines, and the liquid in the raw water pool (1) is driven by the pump bodies to move in a directional manner; The heat exchange module comprises a heat exchanger (6) and a waste heat source, wherein the heat exchanger (6) comprises a cold end and a hot end for exchanging heat; the waste heat outlet of the waste heat source is connected to the hot end inlet of the heat exchanger (6), the hot end outlet of the heat exchanger (6) is connected to the waste heat inlet of the waste heat source, the cold end inlet of the heat exchanger (6) is connected to the liquid outlet of the primary filter tank (5), and the cold end outlet of the heat exchanger (6) is connected to the liquid inlet of the ultrafiltration device (8). The waste heat source is the desulfurized slurry after desulfurization in the desulfurization tower (9) or the cooling water used for cooling steam in the condenser (11) of the steam turbine (10).

2. A system for heating raw water using waste heat as claimed in claim 1, characterized in that: The heat exchanger (6) is a tubular heat exchanger (6) or a plate heat exchanger (6).

3. A system for heating raw water using waste heat as claimed in claim 1, characterized in that: When the waste heat source is the desulfurization slurry after desulfurization in the desulfurization tower (9), the desulfurization tower (9) includes a spray layer located at the top and a slurry oxidation layer located at the bottom, the hot end outlet of the heat exchanger (6) is connected to the spray layer of the desulfurization tower (9), and the hot end inlet of the heat exchanger (6) is connected to the slurry oxidation layer of the desulfurization tower (9).

4. A system for heating raw water using waste heat as claimed in claim 3, characterized in that: The outside of the desulfurization tower (9) is connected to a second circulation pipeline, the two ends of the second circulation pipeline are respectively connected to the spray layer and the slurry oxidation layer, and the hot end outlet of the heat exchanger (6) is connected to the second circulation pipeline.

5. A system for heating raw water using waste heat as claimed in claim 1, characterized in that: The primary filtration module comprises a flocculation tank (2), a sedimentation tank (3), and a sand filter tank (4) which are connected in sequence.

6. A system for heating raw water using waste heat as claimed in claim 1, characterized in that: The flocculation tank (2) is a grid flocculation tank (2).

7. A system for heating raw water using waste heat as claimed in claim 1, characterized in that: When the waste heat source is cooling water used to cool steam in the condenser (11) of the steam turbine (10), the cooling water outlet of the condenser (11) is connected to the hot end inlet of the heat exchanger (6) through a pipeline, and the hot end outlet of the heat exchanger (6) is connected to the cooling water inlet of the condenser (11).

8. A system for heating raw water using waste heat as claimed in claim 7, characterized in that: A cooling tower (13) is connected between the cooling water inlet of the condenser (11) and the hot end outlet of the heat exchanger (6).

9. A system for heating raw water using waste heat as claimed in claim 1, characterized in that: A self-cleaning filter (7) is connected between the ultrafiltration device (8) and the hot end outlet of the heat exchanger (6).

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