Multiphase flow anti-blocking device and desulfurization slurry waste heat recovery system and method

Abstract

The invention discloses a multiphase flow anti-blocking device and a desulfurization slurry waste heat recovery system and method. The desulfurization slurry waste heat recovery system comprises a desulfurization tower, the multiphase flow anti-blocking device, a circulating pump, a heat exchanger and a boiler induced draft fan. A slurry pond is arranged at the bottom of the desulfurization tower, and the multiphase flow anti-blocking device is arranged in the slurry pond; a slurry outlet of the multiphase flow anti-blocking device is sequentially communicated with the circulating pump and the heat exchanger through pipelines, and an outlet of the heat exchanger is communicated with the slurry pond through a pipeline; a backwashing pipeline of the multiphase flow anti-blocking device is communicated with the circulating pump; and the heat exchanger is arranged at an air inlet of the boiler induced draft fan. According to the desulfurization slurry waste heat recovery system, desulfurization slurry waste heat can be directly used for heating boiler air supply, the desulfurization slurry waste heat is utilized to the maximum degree, and meanwhile the slurry waste heat recovery process is simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of energy utilization and environmental protection, and in particular to a multiphase flow anti-blocking device, a desulfurization slurry waste heat recovery system and a method. Background Art

[0002] In recent years, although renewable energy such as solar energy, wind energy, and biomass energy have been greatly developed, they are still unstable and have high investment costs. According to surveys, the total waste heat resources in the thermal power plant industry account for about 67% of the total thermal energy of its fuel, and the recoverable waste heat resources account for about 60% of the total waste heat resources. This not only reduces the efficiency of power plants, but also accelerates the depletion of my country's coal resources and causes great harm to the environment.

[0003] The waste heat from desulfurization slurry accounts for a large proportion of the recoverable waste heat resources. In order to improve the energy utilization efficiency of thermal power plants, many researchers have done a lot of innovative research on the recovery and utilization of waste heat from desulfurization slurry. The desulfurization slurry in the desulfurization tower desulfurizes the high-temperature flue gas while absorbing a large amount of heat energy from the flue gas. However, the excessively high temperature of the desulfurization slurry will lead to a decrease in the desulfurization effect. Therefore, the heat in the desulfurization slurry needs to be recovered and utilized. Most of the current waste heat recovery processes use heat medium liquid to exchange heat with the desulfurization slurry in criss-cross channels. Although the purpose of heat recovery can be achieved, the recovery rate is low and there are still the following defects: (1) The heat exchange time between the desulfurization slurry and the heat medium liquid is short, which reduces the waste heat recovery effect; (2) Storing heat in the heat medium liquid and then sending it to the demand side will cause a large amount of heat energy loss. For example, a Chinese patent document with application number CN 115468177 A discloses a desulfurization slurry waste heat recovery system, which uses a supplementary heat device to supplement heat and adjust the flow of the heat medium flowing between the slurry heat exchanger and the heater. The heat supply end and the demand end cannot directly exchange heat, and two-stage energy conversion must be performed through the heat medium, which inevitably loses some heat, resulting in a relatively low waste heat recovery rate.

[0004] If the desulfurized slurry is directly heat exchanged with the demand side, the utilization efficiency of the waste heat of the desulfurized slurry will be greatly improved. However, the desulfurized slurry contains a large amount of solid particles, which can easily cause blockage of the heat exchange equipment and wear of the pipeline, and needs to be filtered before use. The existing treatment process is to reduce the slurry to an appropriate temperature and then use centrifuges, sedimentation tanks and other filtering equipment for separation and treatment, perform solid-liquid separation to recover heat energy, and finally send the heat energy to the demand side. For example, the Chinese patent document with publication number CN 112675675 A discloses a desulfurized slurry waste heat recovery system and method. Although this treatment method avoids equipment wear and blockage, a large amount of heat energy will still be lost in the filtration and separation stage, and the process flow is cumbersome and the investment is high, and it is impossible to achieve the purpose of completely direct heat exchange.

[0005] Therefore, how to break through the technical bottleneck of direct utilization of waste heat from desulfurization slurry, optimize the process flow, and efficiently recover and utilize the high-temperature waste heat generated during the desulfurization process of desulfurization slurry is the key to improving the efficiency of thermal power plants. Summary of the invention

[0006] The present invention provides a multiphase flow anti-blocking device, a desulfurization slurry waste heat recovery system and method, which can directly use the desulfurization slurry waste heat for heating boiler air supply, maximize the utilization of the desulfurization slurry waste heat, and simplify the slurry waste heat recovery process.

[0007] The technical solution of the present invention is as follows:

[0008] A multiphase flow anti-blocking device comprises a primary filter chamber, a backwashing device, and a secondary filter chamber;

[0009] The primary filter chamber is surrounded by a primary filter screen;

[0010] The backwashing device is arranged in the primary filter chamber, and includes a backwashing pipeline and a plurality of nozzles, and the primary filter screen can be backwashed through the nozzles, and the backwashing pipeline passes through the primary filter screen and communicates with the outside world;

[0011] The secondary filter chamber is surrounded by a secondary filter screen and is arranged in the primary filter chamber; the secondary filter chamber is provided with a slurry outlet, and the slurry outlet is communicated with the slurry heat exchange pipeline.

[0012] Preferably, the aperture of the primary filter is 5-20 mesh; the aperture of the secondary filter is 20-50 mesh.

[0013] Preferably, the top and bottom ends of the primary filter chamber are hollow hemispherical, and the middle section is hollow cylindrical; the filter mesh apertures of the top and middle sections are 5-10 meshes, and the filter mesh aperture of the bottom end is 10-20 meshes.

[0014] The primary filter is mainly used for preliminary filtration of large solid particles in the slurry to prevent blockage and wear of the system pipe network; the bottom filter is set with a relatively large aperture, which can allow the slurry particles with relatively large density to settle and flow out smoothly from the primary filter.

[0015] The top of the secondary filtering chamber is a hollow semicircle, and the middle section is a hollow cylinder without a bottom; the top cavity wall has no holes, and the filter mesh aperture of the middle section is 20-50 meshes.

[0016] The secondary filter with lower density filters the slurry again, further reducing the risk of system blockage; the top seal prevents excessive suction at the top slurry outlet, which would suck large-particle slurry in the primary filter into the pipeline; leaving the bottom empty allows the stratified high-density slurry to settle smoothly, and only transports the upper low-density slurry to the pipeline for heat exchange.

[0017] The present invention also provides a desulfurization slurry waste heat recovery system, including a desulfurization tower, a multiphase flow anti-blocking device, a circulation pump, a heat exchanger, and a boiler induced draft fan;

[0018] The bottom of the desulfurization tower is a slurry pool, and the multiphase flow anti-blocking device is arranged in the slurry pool;

[0019] The slurry outlet of the multiphase flow anti-blocking device is connected to the circulation pump and the heat exchanger in sequence through pipelines, and the heat exchanger outlet is connected to the slurry pool through pipelines; the backwash pipeline of the multiphase flow anti-blocking device is connected to the circulation pump;

[0020] The heat exchanger is arranged at the air inlet of the boiler induced draft fan.

[0021] Preferably, a spray layer, a condensation layer and a demisting layer are sequentially arranged in the tower body above the slurry pool of the desulfurization tower; a smoke inlet is arranged on the tower wall between the slurry pool and the spray layer, and a smoke outlet is arranged on the top of the desulfurization tower.

[0022] Preferably, a stirrer is provided in the slurry pool, and the stirrer is used to mix the slurry in the slurry pool with the slurry after heat exchange, so as to maintain a constant temperature and uniform density in the slurry pool.

[0023] The present invention also provides a method for recovering waste heat from desulfurized slurry based on the desulfurized slurry waste heat recovery system, comprising the following steps:

[0024] (1) After the desulfurized slurry in the slurry pool passes through the primary filter of the multiphase flow anti-blocking device to initially filter out large particles, it enters the secondary filter for further filtration. The low-density desulfurized slurry in the secondary filter enters the pipeline under the action of the circulation pump;

[0025] (2) The desulfurized slurry in the pipeline is transported to the heat exchanger to heat the boiler inlet air;

[0026] (3) After the heat exchange is completed, the desulfurized slurry is sent back to the slurry pool through a pipeline and evenly mixed with the desulfurized slurry in the slurry pool to keep the temperature in the slurry pool constant;

[0027] (4) The high-temperature flue gas entering the desulfurization tower passes through the spray layer, cooling layer, and demister in sequence, completes the desulfurization reaction and is cooled at the same time, and is discharged through the smoke outlet.

[0028] Preferably, the slurry temperature in the slurry pool is 40-60°C, and the boiler inlet air temperature is -20--30°C; after heat exchange in the heat exchanger, the slurry temperature drops to 10-20°C, and the boiler inlet air temperature rises to 5-15°C.

[0029] Preferably, the flue gas inlet temperature of the desulfurization tower is 120-160°C; after the high-temperature flue gas and the desulfurization slurry undergo desulfurization reaction, the flue gas temperature is cooled to 60-70°C.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The desulfurized slurry directly exchanges heat with the cold air entering the boiler through a heat exchanger. On the one hand, the slurry temperature in the slurry pool is maintained, ensuring the desulfurization effect of the high-temperature flue gas; on the other hand, the waste heat of the desulfurized slurry is fully utilized, solving the problem of preheating the boiler air intake and greatly saving the coal consumption of the boiler.

[0032] (2) Due to the deep utilization of the waste heat of the slurry, the desulfurization slurry maintains a low temperature to enhance the cooling effect of the high-temperature flue gas, thereby reducing the flue gas flow rate in the desulfurization tower. The flue gas slowly passes through the packing layer and the spray layer, and is more fully desulfurized and purified, making the treated exhaust gas purer.

[0033] (3) The desulfurization slurry waste heat recovery system of the present invention has a simple structure, does not have excessive devices, has a low cost and has considerable benefits.

[0034] (4) The multiphase flow anti-blocking device of the present invention can be used for in-situ filtration and transportation of multiphase flow containing a mixture of solid, liquid and gas, and is not limited to desulfurization slurry, and can also be used in water conservancy projects such as river dredging. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of a desulfurization slurry waste heat recovery system shown in an embodiment of the present invention;

[0036] Figure 2 It is a structural schematic diagram of a multiphase flow anti-blocking device;

[0037] Figure 3 It is a structural schematic diagram of the first-level filter;

[0038] Figure 4 It is a structural diagram of the secondary filter. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on it. Figure 1 As shown, the present invention discloses a desulfurization slurry waste heat recovery system, including a desulfurization tower 1, a multiphase flow anti-blocking device 2, a slurry circulation pump 3, a slurry heat exchanger 4, an induced draft fan 5, and a backwash valve 6.

[0040] The bottom of the desulfurization tower 1 is a slurry pool 16, in the middle of the slurry pool 16 is provided with a multiphase flow anti-blocking device 2, and a slurry agitator 17 is provided on the side. In the tower body above the slurry pool 16, there are a packing layer 14, a spray layer 13, and a demisting layer 12 from bottom to top. A smoke inlet 15 and a smoke outlet 11 are provided on the left side of the tower body below the packing layer and on the top of the tower body, respectively.

[0041] The multiphase flow anti-blocking device 2 is connected to the slurry circulation pump 3 and the slurry heat exchanger 4 through pipelines, and the outlet of the slurry heat exchanger 4 is connected to the slurry pool 16 through pipelines; in addition, the slurry heat exchanger 4 is located at the air inlet of the induced draft fan 5.

[0042] like Figure 2-Figure 4 As shown, the multiphase flow anti-blocking device 2 includes a primary filter 21 , a backwash device 22 , a secondary filter 24 , a slurry outlet 25 , and a backwash slurry inlet 23 .

[0043] In the multiphase flow anti-blocking device 2, the top and bottom of the primary filter screen 21 are semicircular, the middle is cylindrical, and the interior is hollow.

[0044] The backwashing device 22 is located inside the primary filter 21, has a semicircular top, a hollow cylindrical middle, and no bottom, and is integrally arranged with a backwashing pipeline and a nozzle for backwashing the primary filter 21. A backwashing slurry inlet 23 is provided at the top of the backwashing device 22, passing through the top of the primary filter 21 and communicating with the backwashing pipeline.

[0045] The secondary filter screen 24 is located inside the backwash device 22, has a semicircular top, a hollow cylindrical middle, and no bottom. A slurry outlet 25 is provided at the top of the secondary filter screen 24, and the slurry outlet 25 is connected to the slurry circulation pump 3 through a pipeline.

[0046] The top and middle of the first-stage filter screen 21 are set to 16 meshes, and the bottom is set to 10 meshes; the top of the second-stage filter screen 24 is sealed, and the middle is set to 30 meshes.

[0047] When the primary filter of the multiphase flow anti-blocking device 2 is blocked, the valve 7 can be closed, the backwash valve 6 can be opened, and the slurry circulation pump can be used to backwash the filter with the slurry in the pipeline to solve the filter blockage problem.

[0048] The slurry agitator 17 is used to mix the slurry in the slurry pool 16 with the slurry after heat exchange to maintain a constant temperature and uniform density in the slurry pool.

[0049] A method for recovering waste heat from desulfurized slurry comprises the following steps:

[0050] S1: The desulfurized slurry in the slurry pool 16 maintains uniform density under the action of the slurry agitator 17. After the desulfurized slurry passes through the primary filter of the multiphase flow anti-blocking device 2 to initially filter out large particles, it enters the secondary filter for further filtration. The low-density desulfurized slurry in the secondary filter enters the pipeline under the action of the slurry circulation pump 3;

[0051] S2: The desulfurized slurry in the pipeline is transported to the slurry heat exchanger 4 to heat the boiler inlet air;

[0052] S3: the desulfurized slurry after heat exchange is sent back to the slurry pool 16 through the pipeline, and is evenly mixed with the desulfurized slurry in the slurry pool 16 by the action of the slurry agitator 17 to keep the temperature in the slurry pool 16 constant;

[0053] S4: The high-temperature flue gas entering the desulfurization tower 1 passes through the packing layer 14, the spray layer 13, and the demisting layer 12 in sequence, completes the desulfurization reaction and is cooled, and then is discharged through the smoke outlet 11.

[0054] The flue gas inlet temperature of desulfurization tower 1 is 120-160°C. After the high-temperature flue gas reacts with the desulfurization slurry, the flue gas temperature is cooled to 60-70°C.

[0055] The slurry temperature in the slurry pool 16 is 40-60°C, and the boiler inlet air temperature is -20--30°C; after heat exchange in the slurry heat exchanger 4, the slurry temperature drops to 18°C, and the boiler inlet air temperature rises to 5-15°C.

[0056] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multiphase flow anti-blocking device, characterized in that: It includes a primary filter chamber, a backwashing device, and a secondary filter chamber; The primary filter chamber is surrounded by a primary filter screen; The backwashing device is arranged in the primary filter chamber, and includes a backwashing pipeline and a plurality of nozzles, and the primary filter screen can be backwashed through the nozzles, and the backwashing pipeline passes through the primary filter screen and communicates with the outside world; The secondary filter chamber is surrounded by a secondary filter screen and is arranged in the primary filter chamber; the secondary filter chamber is provided with a slurry outlet, and the slurry outlet is communicated with the slurry heat exchange pipeline.

2. The multiphase flow blocking prevention device according to claim 1, characterized in that: The aperture of the primary filter is 5-20 meshes; the aperture of the secondary filter is 20-50 meshes.

3. The multiphase flow anti-blocking device according to claim 1 or 2, characterized in that: The top and bottom of the primary filter chamber are hollow hemispherical, and the middle section is hollow cylindrical; the filter mesh apertures of the top and middle sections are 5-10 meshes, and the filter mesh aperture of the bottom section is 10-20 meshes.

4. The multiphase flow blocking prevention device according to claim 1 or 2, characterized in that: The top of the secondary filtration chamber is a hollow semicircle, and the middle section is a hollow cylinder without a bottom; The top cavity wall has no holes, and the filter mesh in the middle section has an aperture of 20-50 mesh.

5. A desulfurization slurry waste heat recovery system, characterized in that: It comprises a desulfurization tower, a multiphase flow anti-blocking device according to any one of claims 1 to 4, a circulating pump, a heat exchanger, and a boiler induced draft fan; The bottom of the desulfurization tower is a slurry pool, and the multiphase flow anti-blocking device is arranged in the slurry pool; The slurry outlet of the multiphase flow anti-blocking device is connected to the circulation pump and the heat exchanger in sequence through pipelines, and the heat exchanger outlet is connected to the slurry pool through pipelines; the backwash pipeline of the multiphase flow anti-blocking device is connected to the circulation pump; The heat exchanger is arranged at the air inlet of the boiler induced draft fan.

6. The desulfurization slurry waste heat recovery system according to claim 5, characterized in that: A spray layer, a condensation layer and a demisting layer are sequentially arranged in the tower body above the slurry pool of the desulfurization tower; a smoke inlet is arranged on the tower wall between the slurry pool and the spray layer, and a smoke outlet is arranged on the top of the desulfurization tower.

7. The desulfurization slurry waste heat recovery system according to claim 5, characterized in that: A stirrer is arranged in the slurry pool.

8. A method for recovering waste heat from desulfurized slurry based on the desulfurized slurry waste heat recovery system according to claim 6 or 7, characterized in that: The following steps are involved: (1) After the desulfurized slurry in the slurry pool passes through the primary filter of the multiphase flow anti-blocking device to initially filter out large particles, it enters the secondary filter for further filtration. The low-density desulfurized slurry in the secondary filter enters the pipeline under the action of the circulation pump; (2) The desulfurized slurry in the pipeline is transported to the heat exchanger to heat the boiler inlet air; (3) After the heat exchange is completed, the desulfurized slurry is sent back to the slurry pool through a pipeline and evenly mixed with the desulfurized slurry in the slurry pool to keep the temperature in the slurry pool constant; (4) The high-temperature flue gas entering the desulfurization tower passes through the spray layer, cooling layer, and demister in sequence, completes the desulfurization reaction and is cooled at the same time, and is discharged through the smoke outlet.

9. The method for recovering waste heat from desulfurized slurry according to claim 8, characterized in that: The slurry temperature in the slurry pool is 40-60℃, and the boiler inlet air temperature is -20--30℃; after heat exchange in the heat exchanger, the slurry temperature drops to 10-20℃, and the boiler inlet air temperature rises to 5-15℃.

10. The method for recovering waste heat from desulfurized slurry according to claim 8, characterized in that: The flue gas inlet temperature of the desulfurization tower is 120-160℃; after the high-temperature flue gas and the desulfurization slurry undergo desulfurization reaction, the flue gas temperature is cooled to 60-70℃.

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