A zero-discharge drying system for desulfurization wastewater based on a strong mixer and venturi

Abstract

The present invention discloses a zero-emission drying system for desulfurization wastewater based on a strong mixer and a Venturi, belonging to the field of wastewater desulfurization technology. The system comprises: a bypass flue connected in parallel with the main flue of a boiler, the inlet of the bypass flue being located between the boiler and the air preheater, and the outlet of the bypass flue being located between the air preheater and the dust collector; a drying tower, a Venturi ejector, and a strong mixer located on the bypass flue; the drying tower being connected to the desulfurization tower located on the main flue; the Venturi ejector having an air inlet end, an air outlet end, and an ejector end; the air inlet end being connected to the outlet flue of the drying tower, the air outlet end being connected to the inlet flue of the dust collector, the ejector end being connected to the outlet flue of the dust collector via an ejector pipe, and a booster fan being installed on the ejector pipe; and the strong mixer being located inside the drying tower and being used to mix the flue gas from the bypass flue with the atomized desulfurization wastewater from the desulfurization tower, with the flue gas and wastewater droplets flowing in opposite directions within the strong mixer. Zero emission of desulfurization wastewater is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater desulfurization, and relates to a desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi. Background Art

[0002] In industrial development, the national environmental protection department advocates that industrial enterprises strictly implement desulfurization waste liquid drying technology to achieve zero emission goals.

[0003] In the implementation of the existing desulfurization waste liquid drying technology, when the boiler is started and running at full load, the air preheater resistance is large, and the high-temperature flue gas discharged from the boiler bypasses the air preheater and flows along the bypass flue to the drying tower, and the wastewater treated by the desulfurization tower (desulfurization waste liquid) is introduced into the drying tower. The wastewater is atomized by the atomizer to form wastewater droplets. In the initial operation, the high-temperature flue gas entering the drying tower dries the wastewater droplets, thereby achieving zero wastewater discharge. After a period of time, since the flue gas that has not been treated by the dust collector contains a large amount of dust, the droplets are entrained by the flue gas to the flue gas negative pressure area of ​​the hot air distributor above the atomizer and dry to form crystals that block the hot air distributor, thereby affecting the flue gas flow field distribution in the entire drying tower, and ultimately leading to serious dust accumulation at the bottom of the tower and the system cannot operate.

[0004] When the boiler is started and running at low load, the resistance of the air preheater is small, and most of the high-temperature flue gas discharged from the boiler flows along the main flue in sequence through the air preheater, induced draft fan, dust collector, desulfurization tower, and finally discharged through the chimney, resulting in heat waste. Only a small amount of flue gas bypasses the air preheater and flows along the bypass flue to the drying tower to mix with wastewater (desulfurization waste liquid). Although water enters the atomizer, the flue gas flow rate entering the drying tower is too small, so the wastewater droplets cannot be completely evaporated, causing the wastewater to flow directly into the bottom of the tower, resulting in a wet bottom phenomenon. At the same time, the flue gas that has not been treated by the dust collector contains a large amount of dust, causing ash blockage in the drying tower.

[0005] Therefore, it is necessary to provide a desulfurization wastewater zero-emission drying system that can increase the air inlet volume of the drying tower when the boiler is running at low load. Summary of the Invention

[0006] In order to at least solve the problem in the prior art described above that when the boiler is operating at low load, insufficient air flow into the drying tower causes unevaporated wastewater to flow directly into the tower bottom, resulting in a wet bottom phenomenon, the present invention provides the following technical solution: a zero-emission drying system for desulfurization wastewater based on a strong mixer and a Venturi, comprising: a bypass flue connected in parallel with the main flue of the boiler, the inlet of the bypass flue being located between the boiler and the air preheater, and the outlet of the bypass flue being located between the air preheater and the dust collector, and further comprising: a drying tower, a Venturi ejector, and a strong mixer located on the bypass flue;

[0007] The drying tower is connected to the desulfurization tower located on the main flue;

[0008] The venturi ejector has an air inlet end, an air outlet end and an ejector end, the air inlet end is connected to the outlet flue of the drying tower, the air outlet end is connected to the inlet flue of the dust collector, and the ejector end is connected to the outlet flue of the dust collector through an ejector pipe, and a booster fan is installed on the ejector pipe;

[0009] The strong mixer is located in the drying tower and is used to mix the flue gas from the bypass flue with the atomized desulfurization wastewater from the desulfurization tower. The flue gas and wastewater droplets flow in opposite directions in the strong mixer.

[0010] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, the strong mixer includes: a shell, a guide plate and a main shaft;

[0011] The shell is connected to the inner wall of the drying tower;

[0012] The main shaft is located inside the housing, one end of the main shaft is connected to the output shaft of the motor, and a plurality of guide plates are arranged on the circumferential outer wall of the main shaft;

[0013] The guide plate is arranged at an angle to the horizontal plane.

[0014] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, the desulfurization wastewater zero-discharge drying system further comprises: a pressure pump;

[0015] The booster pump is installed in the drying tower and is connected to the drainage pipe of the desulfurization tower. A nozzle is installed at the water outlet of the booster pump for spraying the desulfurization wastewater toward the air outlet of the strong mixer.

[0016] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, the strong mixer further comprises: a diverter cone;

[0017] The diverter cone is located at the other end of the main shaft, and the tip of the diverter cone is arranged in the opposite direction of the flue gas flow.

[0018] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, the strong mixer further comprises: a diffusion hood;

[0019] The diffusion cover is located outside the main shaft, and the tip of the diversion cover is connected to the guide plate to increase the flow rate of the smoke after passing through the guide plate.

[0020] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, the diverter cone is a blunt body, and a wear-resistant layer is provided on the windward outer wall of the diverter cone and / or the diffusion cover.

[0021] Optionally, in the above-mentioned zero-emission drying system for desulfurization wastewater based on a strong mixer and a venturi, the diffusion cover is in the shape of a hollow conical column, and a plurality of through holes are opened along the circumference of the side wall, and the maximum diameter of the diffusion cover is greater than the maximum diameter of the diverter cone.

[0022] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, isolation valves are provided at the inlet and outlet of the booster fan.

[0023] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, a pressure transmitter is provided at the outlet of the booster fan.

[0024] Optionally, in the above-mentioned desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi, the outlet flue of the drying tower is located above the lower cone hopper of the drying tower.

[0025] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0026] The present application installs a Venturi ejector between the drying tower and the dust collector, and adds a booster fan between the ejector end of the Venturi ejector and the outlet flue of the dust collector, thereby providing power for the drying flue gas through external force driving, so that the flue gas flow rate in the drying tower can still maintain a reasonable flow rate and flow rate even under low load conditions. At the same time, a high-speed rotating strong mixer is used to fully mix the flue gas with the atomized desulfurization wastewater, thereby achieving the goal of zero discharge of desulfurization wastewater and solving the problem of insufficient air intake in the drying tower causing the wastewater that has not yet evaporated to flow directly into the bottom of the tower, resulting in a wet bottom phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of a desulfurization waste liquid drying system in the prior art;

[0028] Figure 2 A schematic structural diagram of a zero-discharge drying system for desulfurization wastewater based on a strong mixer and a venturi according to an embodiment of the present invention;

[0029] Figure 3 for Figure 2 Schematic diagram of the structure of the Chinese Qiuli ejector;

[0030] Figure 4 for Figure 2 Schematic diagram of the structure of the medium-intensity mixer;

[0031] In the figure: 1. Drying tower; 2. Venturi ejector; 201. First convergent pipe; 202. First nozzle pipe; 203. First expansion pipe; 204. Elbow pipe; 205. Second convergent pipe; 206. Second nozzle pipe; 3. Booster fan; 4. Strong mixer; 401. Shell; 402. Guide plate; 403. Main shaft; 404. Diverter cone; 405. Diffuser; 5. Air preheater; 6. Dust collector; 7. Reinforcement plate; 8. Wear-resistant layer; 9. Drying tower outlet flue; 10. Ejector pipe; 11. Main flue; 12. Bypass flue; 13. Booster pump; 14. Pressure transmitter; 15. Motor. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0033] In the description of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connected", "connected", and "set" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components; they can be wired electrical connections, radio connections, or wireless communication signal connections. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] See also Figure 2-4 The present invention provides the following technical solution: a zero-emission drying system for desulfurization wastewater based on a strong mixer and a venturi, comprising: a bypass flue 12 and a drying tower 1, a venturi ejector 2 and a strong mixer 4 installed on the bypass flue 12.

[0035] Specifically, the bypass flue 12 is arranged in parallel with the boiler main flue 11 (see Figure 1 As shown), the inlet of the bypass flue 12 is located between the boiler and the air preheater 5, and the outlet of the bypass flue 12 is located between the air preheater 5 and the dust collector 6 (such as an electrostatic precipitator ESP). The drying tower 1 is connected to the desulfurization tower located on the main flue 11. Figure 2As shown, the venturi ejector 2 has an air inlet end, an air outlet end and an ejector end. The air inlet end is connected to the outlet flue 9 of the drying tower, the air outlet end is connected to the inlet flue of the dust collector 6, and the ejector end is connected to the outlet flue of the dust collector 6 through an ejector pipe 10. The structure of the venturi ejector 2 is designed and made using the Venturi principle. When the boiler is running at low load, the venturi ejector 2 is used as a driving device. When in use, the flue gas flowing out of the drying tower 1 can be ejected into the dust collector 6. Preferably, the outlet flue 9 of the drying tower is located above the lower cone hopper of the drying tower 1. A booster fan 3 is installed on the ejector pipe 10, which is used to introduce a portion of the clean flue gas purified by the dust collector 6 into the venturi ejector 2. The strong mixer 4 is located in the drying tower 1. The strong mixer 4 is used to mix the flue gas from the bypass flue 12 with the desulfurization wastewater from the desulfurization tower after atomization. When the boiler is running at low load, the Venturi ejector 2 is started. Initially, a small amount of high-temperature flue gas bypasses the air preheater 5 and flows into the drying tower 1 along the bypass flue 12. The strong mixer 4 rotates at high speed to generate centrifugal force, mixing the flue gas with the atomized desulfurization wastewater from the desulfurization tower to form dry exhaust gas. The exhaust gas flows along the outlet flue 9 of the drying tower 1 to the Venturi ejector 2. The negative pressure area in the Venturi ejector 2 adsorbs the exhaust gas, attracting it to enter, and drives more flue gas into the drying tower 1 to form exhaust gas, increasing the outlet negative pressure of the drying tower 1, and starting at the same time. The booster fan 3 extracts an appropriate amount of clean flue gas purified by the dust collector 6. The clean flue gas serves as a driving source and flows into the venturi ejector 2 along the ejector pipe 10, further increasing the negative pressure at the outlet of the drying tower 1, thereby increasing the air (flue gas) intake of the drying tower 1. The flue gas and the wastewater droplets flow in opposite directions in the strong mixer 4. The continuous high-temperature flue gas is fully mixed with the atomized desulfurization wastewater, achieving the goal of zero discharge of desulfurization wastewater and solving the problem of insufficient air intake of the drying tower 1, which causes the unevaporated wastewater to flow directly into the bottom of the tower and produce a wet bottom phenomenon. The strong mixer 4 can be a strong mixer 4 in the prior art, and this embodiment does not limit the specific structure of the strong mixer 4.

[0036] Reference Figure 3 As shown, as an embodiment of the specific structure of the above-mentioned strong mixer 4, in this embodiment, the strong mixer 4 includes: a shell 401, a guide plate 402 and a main shaft 403. The shell 401 is connected to the inner wall of the drying tower 1 using common technical means in this field. The main shaft 403 is located on the inner side of the shell 401, and one end of the main shaft 403 is connected to the output shaft of the motor 15. A plurality of guide plates 402 are arranged on the circumferential outer wall of the main shaft 403. The guide plates 402 are arranged at intervals to form a plurality of flue gas channels. The main shaft 403 rotates under the drive of the motor 15, and at the same time drives the plurality of guide plates 402 to rotate in the same direction on the inner side of the shell 401. The guide plates 402 are arranged at an angle to the horizontal plane. Preferably, the guide plates 402 are streamlined and have little resistance to the flue gas.

[0037] In order to atomize the desulfurization wastewater entering the drying tower 1, the desulfurization wastewater zero-discharge drying system further includes: a pressure pump 13 (not shown in the figure). Figure 2 As shown, a booster pump 13 is installed within the drying tower 1 and is connected to the desulfurization tower's drainage pipe. A nozzle is installed at the water outlet of the booster pump 13. When the booster pump 13 is activated, desulfurized wastewater flows along the drainage pipe into the booster pump 13. The booster pump 13 acts as a power device to pressurize the desulfurized wastewater and spray the high-pressure wastewater toward the outlet of the mixer 4. The high-pressure wastewater passes through the nozzle of the booster pump 13 to form wastewater droplets. The wastewater droplets mix with the high-temperature flue gas passing through the mixer 4, and the wastewater droplets evaporate to form exhaust gas. As can be understood, the desulfurized wastewater is sprayed in the opposite direction of the flue gas flow.

[0038] Reference Figure 3 As shown in FIG. 4 , as a preferred embodiment of the specific structure of the strong mixer 4, in this embodiment, the strong mixer 4 further includes a diverter cone 404. The diverter cone 404 is located at the other end of the main shaft 403 (the end away from the motor 15), with the tip of the diverter cone 404 facing in the opposite direction of the flue gas flow. The diverter cone 404 diverts the flue gas flowing into the strong mixer 4 through the bypass flue 12 and flows into the flue gas channel between the guide plates 402.

[0039] In order to avoid dust accumulation in the drying tower 1 and the flue, the strong mixer 4 also includes: a diffusion cover 405. The diffusion cover 405 is located on the outside of the main shaft 403, and the tip of the diffusion cover 405 is connected to the guide plate 402. When the strong mixer 4 is started, the diffusion cover 405 can rotate in the same direction as the guide plate 402. The diffusion cover 405 can increase the flow rate of the flue gas after passing through the guide plate 402. Since these flue gases carry some dust, the increase in the flue gas flow rate can prevent dust from settling in the drying tower 1 and the flue. Preferably, the diverter cone 404 is a blunt body (i.e., a non-streamlined body) with a large pressure difference resistance. A wear-resistant layer 8, such as wear-resistant ceramics, is provided on the windward outer wall of the diverter cone 404 and / or the diffusion cover 405 to reduce the impact force of the flue gas on the diverter cone 404 and / or the diffusion cover 405, thereby improving the service life of the diverter cone 404 and / or the diffusion cover 405. Further preferably, the diffusion cover 405 is in the shape of a hollow conical column and has a plurality of through holes along the circumference of the side wall. After the flue gas passes through the high-speed rotating guide plate 402, a portion of it can flow out through the through holes of the diffusion cover 405, thereby reducing the impact of the flue gas on the diffusion cover 405. The maximum diameter of the diffusion cover 405 is greater than the maximum diameter of the diverter cone 404, thereby increasing the flue gas flow rate. It should be noted that in order to better reflect the position of the diffusion cover 405 in the strong mixer 4, Figure 3 The height of the housing 401 of the medium-intensity mixer 4 does not represent the actual height.

[0040] To accurately control the flow direction of the driving source of the Venturi ejector 2 (referring to the clean flue gas purified by the dust collector 6), isolation valves (not shown) are installed at the inlet and outlet of the booster fan 3. These valves isolate the fluid and can quickly and accurately cut off the flow of flue gas. Preferably, a pressure transmitter 14 is installed at the outlet of the booster fan 3 to monitor the output gas (referring to the flue gas) pressure of the booster fan 3.

[0041] As an example of the specific structure of the aforementioned Venturi ejector 2, in this embodiment, the Venturi ejector 2 is a sleeve tube comprising an inner tube and an outer tube; the air inlet end of the outer tube is connected to the outlet flue 9 of the drying tower, and the air outlet end of the outer tube is connected to the inlet flue of the dust collector 6. The ejector end of the inner tube is connected to the outlet flue of the booster fan 3, and the air outlet end of the inner tube extends into the outer tube. In this way, clean flue gas extracted by the booster fan 3 and filtered by the dust collector 6 enters the inner tube, and then passes through the inner tube jet and enters the outer tube. When the boiler is running at low load, part of the high-temperature flue gas discharged from the boiler bypasses the air preheater 5 and flows into the drying tower 1 along the bypass flue 12. It is mixed with the atomized desulfurization wastewater from the desulfurization tower through the strong mixer 4 to form dry exhaust gas. The exhaust gas flows into the outer pipe through the outlet flue 9 of the drying tower. The negative pressure area in the outer pipe has an adsorption effect on the exhaust gas, thereby attracting more flue gas into the drying tower 1 to form exhaust gas. After passing through the outer pipe, the exhaust gas flows into the inlet flue of the dust collector 6. After starting the booster fan 3, the booster fan 3 extracts a small amount of clean flue gas filtered by the dust collector 6. The clean flue gas flows into the inner pipe along the ejector pipe 10 and enters the outer pipe through the jet, and then flows into the inlet flue of the dust collector 6. It should be noted that both the inner pipe and the outer pipe are designed according to the Venturi principle, and each has a negative pressure area inside. This embodiment does not limit its specific structure. Preferably, a wear-resistant layer 8, such as wear-resistant ceramic, is provided on the windward outer wall of the inner tube and the inner wall of the outer tube to reduce the impact of the flue gas on the windward outer wall of the inner tube and the inner wall of the outer tube, thereby increasing the service life of the inner tube and the outer tube.

[0042] Reference Figure 4As shown, the outer tube comprises a first reducer 201, a second nozzle 202, and a first expander 203. The diameter of the first reducer 201 gradually decreases along the flue gas flow direction. This increases the flue gas flow rate (and pressure) as the cross-section of the first reducer 201 decreases. This creates a pressure difference between the two ends of the first reducer 201, which attracts the incoming flue gas and attracts more flue gas, thereby increasing the air intake of the drying tower 1. One end of the second nozzle 202 is connected to the outlet of the first reducer 201, while the other end is connected to the inlet of the first expander 203. This allows the high-pressure flue gas flowing out of the first reducer 201 to flow rapidly into the first expander 203 through the second nozzle 202. The diameter of the first expander 203 gradually increases along the flue gas flow direction. This reduces the flow rate (and pressure) of the high-pressure flue gas as the cross-section increases, thereby preventing the high-pressure flue gas from impacting the inner wall of the flue. The inner tube includes an elbow tube 204, a second tapered tube 205, and a second nozzle tube 206. The elbow tube 204 is fixed in the outlet flue 9 of the drying tower 1. For example, four reinforcement plates 7 are arranged around the circumference of the elbow tube 204. The elbow tube 204 is connected to the inner wall of the flue through the reinforcement plates 7. One end of the elbow tube 204 is connected to the outlet flue of the booster fan 3. In this way, the booster fan 3 can discharge clean flue gas filtered by the dust collector 6 into the elbow tube 204. The diameter of the second reducer 205 gradually decreases along the direction of the flue gas flow. One end of the second reducer 205 is connected to the elbow pipe 204, and the other end of the second reducer 205 is connected to the air inlet end of the second nozzle pipe 206. The other end of the second reducer 205 and the second nozzle pipe 206 are both located inside the air inlet end of the outer pipe. The clean flue gas flows into the second reducer 205 along the elbow pipe 204. Its flow rate (and air pressure) increases as the cross-section of the second reducer 205 decreases, and a pressure difference is generated at both ends of the second reducer 205, which has a certain adsorption effect on the clean flue gas that is close to it, attracting more clean flue gas to gather, and then injected into the outer pipe (specifically the first reducer 201) through the second nozzle pipe 206. It should be noted that Figure 4 The arrows in the figure represent the direction of flue gas flow.

[0043] It is understood from common technical knowledge that the present invention may be implemented by other embodiments that do not depart from its spirit or essential features. Therefore, the embodiments disclosed above are, in all respects, merely illustrative and not exclusive. All modifications within the scope of the present invention or equivalent to the scope of the present invention are intended to be encompassed by the present invention.

Claims

1. A zero-discharge drying system for desulfurization wastewater based on a strong mixer and a venturi, characterized in that: include: A bypass flue connected in parallel with the main flue of the boiler, wherein the inlet of the bypass flue is located between the boiler and the air preheater, and the outlet of the bypass flue is located between the air preheater and the dust collector, and further comprising: a drying tower, a venturi ejector and a strong mixer located on the bypass flue; The drying tower is connected to the desulfurization tower located on the main flue; The venturi ejector has an air inlet end, an air outlet end and an ejector end, the air inlet end is connected to the outlet flue of the drying tower, the air outlet end is connected to the inlet flue of the dust collector, and the ejector end is connected to the outlet flue of the dust collector through an ejector pipe, and a booster fan is installed on the ejector pipe; The strong mixer is located in the drying tower and is used to mix the flue gas from the bypass flue with the atomized desulfurization wastewater from the desulfurization tower. The flue gas and wastewater droplets flow in opposite directions in the strong mixer. The strong mixer comprises: a shell, a guide plate, a main shaft, a splitter cone and a diffusion cover; The shell is connected to the inner wall of the drying tower; The main shaft is located inside the housing, one end of the main shaft is connected to the output shaft of the motor, and a plurality of guide plates are arranged on the circumferential outer wall of the main shaft; The guide plate is arranged at an angle to the horizontal plane; The diverter cone is located at the other end of the main shaft, and the tip of the diverter cone is arranged in the opposite direction of the flue gas flow; The diffusion cover is located outside the main shaft, and the tip of the diffusion cover is connected to the guide plate to increase the flow rate of the smoke after passing through the guide plate; The diverter cone is a blunt body, and a wear-resistant layer is provided on the windward outer wall of the diverter cone and / or the diffuser cover; The diffusion cover is in the shape of a hollow conical column and is provided with a plurality of through holes along the circumference of the side wall. The maximum diameter of the diffusion cover is greater than the maximum diameter of the diverter cone.

2. The desulfurization wastewater zero-discharge drying system based on a strong mixer and a venturi according to claim 1 is characterized in that: The desulfurization wastewater zero-discharge drying system further includes: a pressure pump; The booster pump is installed in the drying tower and is connected to the drainage pipe of the desulfurization tower. A nozzle is installed at the water outlet of the booster pump for spraying the desulfurization wastewater toward the air outlet of the strong mixer.

3. The zero-discharge drying system for desulfurization wastewater based on a strong mixer and a venturi according to claim 1 is characterized in that: The inlet and outlet of the booster fan are both provided with isolation valves.

4. The zero-discharge drying system for desulfurization wastewater based on a strong mixer and a venturi according to claim 1 is characterized in that: The outlet of the booster fan is provided with a pressure transmitter.

5. The zero-discharge drying system for desulfurization wastewater based on a strong mixer and a venturi according to claim 1 is characterized in that: The outlet flue of the drying tower is located above the lower cone hopper of the drying tower.

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