Desulfurization device and method for large ships

Abstract

The present invention discloses a desulfurization device and method for large ships, comprising a desulfurization tower, a seawater lift pump, a flue gas heat exchanger, a cyclone sedimentation tank, and a microbubble generator. The desulfurization tower is provided with a flue gas outlet at the top and a liquid discharge port at the bottom. An air inlet is provided above the liquid discharge port within the desulfurization tower. A first spray pipe is provided near the upper end of the air inlet within the desulfurization tower. Two layers of cyclone atomizers are provided above the first spray pipe within the desulfurization tower. The upper cyclone atomizer is connected to the seawater lift pump. The liquid discharge port at the bottom of the desulfurization tower is connected to the water inlet of the cyclone sedimentation tank. The water outlet of the cyclone sedimentation tank is connected to the microbubble generator, and the microbubble generator is respectively connected to the cyclone atomizer at the lower layer. The advantages of the present invention are that while achieving a high desulfurization effect, the desulfurization rate is also higher. At the same time, wastewater is precipitated and removed for reuse, avoiding impact on marine water quality.

Description

Technical Field

[0001] The present invention relates to the technical field of ship exhaust desulfurization, and in particular to a desulfurization device and method for large ships. Background Art

[0002] With the increase in global trade, shipping, as an important means of transportation, has seen rapid growth in its capacity in the 21st century. However, ship exhaust contains large amounts of sulfur oxides (SO2) and nitrogen oxides (NO2), causing severe air pollution. The international community and regional organizations have enacted legislation to limit pollutant emissions from ships. With increasingly stringent national emission regulations, controlling sulfur and nitrogen oxide emissions from ships is becoming increasingly urgent.

[0003] Currently, there are several key measures to control the sulfur content in ship engine exhaust: 1. Using low-sulfur heavy fuel oil. Using low-sulfur fuel oil will increase shipping companies' operating costs, with an estimated increase of over 30%, which will reduce the competitiveness of shipping in the industry. In addition to the fuel costs, using low-sulfur fuel oil also requires modifications to the entire engine fuel system. This is because high-sulfur heavy fuel oil has different physical and chemical properties, flash point, viscosity, specific gravity, calorific value, and other parameters, and therefore places different requirements on the engine. 2. Using liquefied natural gas as fuel presents difficulties and high costs in modifying the engine fuel system. Natural gas storage issues on ships result in reduced cruising range, and current port refueling infrastructure is incomplete. 3. Installing and using ship engine exhaust gas desulfurization equipment, while increasing the investment cost of some equipment, avoids modifying the engine system and has significantly lower operating costs than switching to low-sulfur heavy fuel oil, making it highly economical.

[0004] Seawater desulfurization utilizes the alkalinity of seawater to remove sulfur dioxide and sulfur trioxide from flue gas. Traditionally, large amounts of seawater are sprayed into the flue gas absorber, where the sulfur dioxide and sulfur trioxide are absorbed and removed. The purified flue gas is then demisted by a demister and heated by a flue gas heat exchanger before being discharged. The wastewater generated by desulfurization can be discharged directly into the sea. Existing flue gas treatment methods are unsatisfactory, and direct discharge of wastewater into the sea significantly damages marine water quality. Summary of the Invention

[0005] The purpose of the present invention is to provide a desulfurization device and method for large ships, which can achieve efficient desulfurization effect and higher desulfurization rate. At the same time, wastewater is precipitated and removed before reuse, avoiding impact on marine water quality.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A desulfurization device for large ships, characterized in that it includes a desulfurization tower, a seawater lifting pump, a flue gas heat exchanger, a cyclone sedimentation tank and a microbubble generator, wherein a flue gas outlet is provided at the top of the desulfurization tower and a liquid discharge port is provided at the bottom. An air inlet is provided above the liquid discharge port inside the desulfurization tower, and the air inlet is connected to the air flow section of the flue gas heat exchanger. A first spray pipe is provided near the upper end of the air inlet inside the desulfurization tower, and the first spray pipe is connected to a stirring tank. The front end of the stirring tank is connected to the liquid flow section of the flue gas heat exchanger. Two layers of cyclone atomizers are provided above the first spray pipe inside the desulfurization tower. The cyclone atomizer on the upper layer is connected to the seawater lifting pump, the drain port at the bottom of the desulfurization tower is connected to the water inlet of the cyclone sedimentation tank, the water outlet of the cyclone sedimentation tank is connected to the microbubble generator, and the microbubble generator is connected to the cyclone atomizer on the lower layer respectively. A dielectric barrier low-temperature plasma reactor is provided above the cyclone atomizer inside the desulfurization tower, a second spray pipe is provided above the dielectric barrier low-temperature plasma reactor, and the second spray pipe is connected to a feed pump outside the desulfurization tower, an induced draft fan is provided at the flue gas outlet, and a demister is provided below the flue gas outlet inside the desulfurization tower.

[0008] Preferably, a plurality of spray heads are equidistantly distributed on the first spray pipe and the second spray pipe.

[0009] Preferably, eight groups of the cyclone atomizers are provided in each layer, and the eight groups of the cyclone atomizers are arranged in a tangential circular direction on the inner wall of the desulfurization tower.

[0010] Preferably, an electric stirrer is provided in the stirring tank, and a thermometer, a first stop valve and a feeding pump are provided on the pipe connecting the first spray pipe and the stirring tank.

[0011] Preferably, a second stop valve is provided at the connection point between the air inlet and the air flow section of the flue gas heat exchanger, and a third stop valve is provided between the feed pump and the second spray pipe.

[0012] Preferably, the inlet of the seawater lifting pump is connected to the sea surface of the ship, a replaceable filter is provided at the inlet of the seawater lifting pump, and a fourth stop valve is provided between the seawater lifting pump and the upper cyclone atomizer.

[0013] Preferably, one end of the microbubble generator is further connected to an ozone generator, and a fifth shut-off valve is provided between the microbubble generator and the cyclone atomizer on the lower layer.

[0014] Preferably, an aeration pipe is provided in the cyclone sedimentation tank, the aeration pipe is connected to the ozone generator, the aeration direction of the aeration pipe is arranged in a tangential direction to the inner wall of the cyclone sedimentation tank, a sedimentation tank is provided at the bottom of the cyclone sedimentation tank, an electric feeding screw is provided in the sedimentation tank, a discharge port is provided at the outlet end of the electric feeding screw on one side of the cyclone sedimentation tank, an electric gate valve is provided at the discharge port, a partition is provided on the side away from the aeration pipe in the cyclone sedimentation tank, an inclined tube clarification area is provided in the cyclone sedimentation tank on the other side away from the aeration pipe by the partition, the inclined tube clarification area is connected to the bottom of the cyclone sedimentation tank, two groups of inclined tubes placed in opposite directions are provided in the inclined tube clarification area, the inclination angle of the inclined tubes is 60°, and the water outlet is provided above the inclined tube clarification area.

[0015] A seawater desulfurization method for large ships, characterized by comprising the following steps:

[0016] Step 1: First, open the second stop valve and the fourth stop valve. The flue gas generated by the ship enters the desulfurization tower and comes into contact with the seawater output by the cyclone atomizer to achieve preliminary treatment.

[0017] Step 2: The dielectric barrier low-temperature plasma reactor is turned on to release the low-temperature plasma. At the same time, the feed pump is turned on to spray ethanolamine from above the dielectric barrier low-temperature plasma reactor through the second spray pipe. The desulfurization reaction of the flue gas is achieved through the combination of ethanolamine and the plasma environment.

[0018] Step 3: When the flue gas heat exchanger reaches the preset operating temperature, water is introduced. After the water is heated by the flue gas heat exchanger, it enters the mixing tank. Urea is added to the mixing tank while stirring. When the urea solution reaches the preset initial temperature, the first stop valve is opened to exchange heat with the high-temperature flue gas at the air inlet through the feeding pump and achieve hydrolysis, thereby treating the high-temperature flue gas.

[0019] Step 4: The water at the bottom of the desulfurization tower is discharged into the cyclone sedimentation tank. The ozone in the aeration pipe enters the cyclone sedimentation tank in the form of a cyclone, causing the water flow in the tank to generate a horizontal cyclone perpendicular to the main flow, thereby sinking the sediment in the water into the sedimentation tank. The sediment is then discharged from the discharge port through the electric feeding screw. The water entering the inclined tube clarification area subsequently reacts with ozone to form a water body containing microbubble ozone and enters the desulfurization tower for further desulfurization treatment.

[0020] Step 5: After undergoing multiple treatment processes, the flue gas passes through the demister and is discharged to the outside of the desulfurization tower through the induced draft fan.

[0021] Preferably, the controlled discharge current of the dielectric barrier low-temperature plasma reactor in step 2 is 0.83~4.16A, the discharge voltage is 0~20KV, the discharge frequency is 8.7kHz~11.0kHz, the discharge power is 8~90W, and the feed speed of ethanolamine is 2~3m 3 / h.

[0022] In summary, the present invention has the following beneficial effects:

[0023] 1. The present invention allows urea in an aqueous solution to contact high-temperature flue gas in a spraying state, and the urea is converted into a portion of solid urea and water vapor. The solid urea undergoes thermal decomposition and hardening at high temperature, and the solid urea is rapidly converted into a mixture of ammonia and isohydrogen acid. The mixture appears in the form of gas and is extremely stable. The isohydrogen acid reacts with the water vapor therein to produce ammonia, which can quickly produce a preliminary desulfurization effect on the flue gas.

[0024] 2. The method of the present invention utilizes a pulsed high-voltage power supply to generate high-energy electrons in the reactor, which collide with molecules such as H2O, O2, and N2 in the exhaust gas to generate highly active free radicals. These substances react with gaseous pollutants such as SO2 in the exhaust gas to achieve the purpose of removal.

[0025] 3. The present invention introduces ozone into the water body after desulfurization treatment for cyclone precipitation, and then generates microbubbles through ozone. The bubble space in the microbubble solution itself will produce a variety of active free radicals (hydroxyl ions, active oxygen ions, hydrogen ions, etc.), among which the hydroxyl ions have super strong oxidizing ability, thereby generating a certain desulfurization ability.

[0026] 4. The present invention realizes efficient desulfurization of flue gas and at the same time, wastewater is precipitated and removed before reuse, thus avoiding impact on ocean water quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 Schematic diagram of the distribution of cyclone atomizers in each layer of the present invention;

[0029] Figure 3 It is a schematic diagram of the internal structure of the cyclone sedimentation tank in the present invention. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. This embodiment does not constitute a limitation to the present invention.

[0031] like Figures 1 to 3The desulfurization device shown is for large ships, comprising a desulfurization tower 1, a seawater lifting pump 2, a flue gas heat exchanger 3, a cyclone sedimentation tank 4 and a microbubble generator 5. The desulfurization tower 1 is provided with a flue gas outlet 6 at the top and a liquid discharge port 7 at the bottom. An air inlet 8 is provided above the liquid discharge port 7 inside the desulfurization tower 1. The air inlet 8 is connected to the air flow section of the flue gas heat exchanger 3. A first spray pipe 9 is provided near the upper end of the air inlet 8 inside the desulfurization tower 1. The first spray pipe 9 is connected to a stirring tank 10. The front end of the stirring tank 10 is connected to the liquid flow section of the flue gas heat exchanger 3. Two layers of cyclone atomizers 11 are provided above the first spray pipe 9 inside the desulfurization tower 1. The upper layer of the cyclone atomizer 11 is provided. The flow atomizer 11 is respectively connected to the seawater lifting pump 2, the discharge port 7 at the bottom of the desulfurization tower 1 is connected to the water inlet of the cyclone sedimentation tank 4, the water outlet of the cyclone sedimentation tank 4 is connected to the microbubble generator 5, and the microbubble generator 5 is respectively connected to the cyclone atomizer 11 in the lower layer. A dielectric barrier low-temperature plasma reactor 12 is provided above the cyclone atomizer 11 inside the desulfurization tower 1, and a second spray pipe 13 is provided above the dielectric barrier low-temperature plasma reactor 12. The second spray pipe 13 is connected to a feed pump 14 outside the desulfurization tower 1, an induced draft fan 15 is provided at the flue gas outlet 6, and a demister 16 is provided below the flue gas outlet 6 inside the desulfurization tower 1.

[0032] There are several spray heads distributed at equal intervals on the first spray pipe 9 and the second spray pipe 13. There are eight groups of cyclone atomizers 11 on each layer. The eight groups of cyclone atomizers 11 are arranged in a tangential circular direction on the inner wall of the desulfurization tower 1. The cyclone atomization is more comprehensive, the gas-liquid mixing effect is higher, and the overall reaction degree is improved.

[0033] An electric stirrer is provided in the mixing tank 10, and a thermometer 17, a first stop valve 18 and a feeding pump 19 are provided on the connecting pipe between the first spray pipe 9 and the mixing tank 10. A second stop valve 20 is provided at the connection point between the air inlet 8 and the air flow section of the flue gas heat exchanger 3, and a third stop valve 21 is provided between the feed pump 14 and the second spray pipe 13. The inlet of the seawater lifting pump 2 is connected to the sea surface of the ship, and a replaceable filter 22 is also provided at the inlet of the seawater lifting pump 2. A fourth stop valve 23 is also provided between the seawater lifting pump 2 and the upper cyclone atomizer 11, and an ozone generator 24 is also connected to one end of the microbubble generator 5. A fifth stop valve 25 is provided between the microbubble generator 5 and the lower cyclone atomizer 11.

[0034] An aeration pipe 26 is provided in the cyclone sedimentation tank 4, and the aeration pipe 26 is connected to the ozone generator 24. The aeration direction of the aeration pipe 26 is set in a tangential direction on the inner wall of the cyclone sedimentation tank 4. A sedimentation tank 27 is provided at the bottom of the cyclone sedimentation tank 4. An electric feeding screw 28 is provided in the sedimentation tank 27. A discharge port 29 is provided at the outlet end of the electric feeding screw 28 on one side of the cyclone sedimentation tank 4. An electric gate valve 30 is provided at the discharge port 29. A partition 31 is provided on the side away from the aeration pipe 26 in the cyclone sedimentation tank 4. The cyclone sedimentation tank 4 is connected to the cyclone sedimentation tank 4 through the partition 31. An inclined tube clarification zone is separated from the other side of the aeration pipe 26. The inclined tube clarification zone is connected to the bottom of the cyclone sedimentation tank 4. Two groups of inclined tubes 32 placed in opposite directions are provided in the inclined tube clarification zone. The inclined tube 32 has an inclination angle of 60°. The water outlet is set above the inclined tube clarification zone. The generated sediment is transported to the discharge port 29 by the electric feeding screw 28 for subsequent discharge. The subsequent water body passes through the two groups of inclined tubes in the inclined plate clarification zone, which greatly slows down the flow rate of the water body and can intercept the generated floc impurities to the greatest extent. The water body then reacts with ozone to form microbubble water body.

[0035] A seawater desulfurization method for large ships comprises the following steps:

[0036] Step 1: First, open the second stop valve 20 and the fourth stop valve 23. The flue gas generated by the ship enters the desulfurization tower 1 and is cooled by contact with the seawater output by the cyclone atomizer 11 to achieve preliminary treatment. The seawater cyclone atomization system has a higher desulfurization effect and a lower operating pressure drop, which can effectively reduce the floor space of the desulfurization tower, thereby having better load fluctuation resistance.

[0037] Step 2: Turn on the dielectric barrier low-temperature plasma reactor 12 to release the low-temperature plasma. The dielectric barrier low-temperature plasma reactor 12 is controlled to have a discharge current of 0.83-4.16A, a discharge voltage of 0-20KV, a discharge frequency of 8.7kHz-11.0kHz, a discharge power of 8-90W, and a feed speed of ethanolamine of 2-3m / s. 3 / h, and at the same time, the feed pump 14 is turned on. The feed pump 14 sprays ethanolamine from above the dielectric barrier low-temperature plasma reactor 12 through the second spray pipe 13. The desulfurization reaction of the flue gas is achieved by combining ethanolamine with the plasma environment. A pulsed high-voltage power supply is used to generate high-energy electrons in the reactor 12, which collide with molecules such as H2O, O2, and N2 in the exhaust gas to generate highly active free radicals. These substances react with gaseous pollutants such as SO2 in the exhaust gas to achieve the purpose of removal.

[0038] Step 3: When the flue gas heat exchanger 3 reaches the preset working temperature, water is introduced. After the water is heated by the flue gas heat exchanger 3, it enters the stirring tank 10. Urea is added to the stirring tank 10 while stirring. When the urea solution reaches the preset initial temperature, the first stop valve 18 is opened to exchange heat with the high-temperature flue gas at the air inlet 8 through the feeding pump 19 and realize hydrolysis, thereby treating the high-temperature flue gas. The urea in the aqueous solution state contacts the high-temperature flue gas in a spraying state, and the urea dissolves and converts into a part of solid urea and water vapor. The solid urea undergoes thermal decomposition and hardening at high temperature, and the solid urea is quickly converted into a mixture of ammonia and isohydrogen acid. The mixture appears in the form of gas and is extremely stable. The isohydrogen acid reacts with the water vapor therein to produce ammonia, which can quickly produce a preliminary desulfurization effect on the flue gas.

[0039] Step 4: The water at the bottom of the desulfurization tower 1 is discharged into the cyclone sedimentation tank 4, and the ozone in the aeration pipe 26 enters the cyclone sedimentation tank 4 in the form of a cyclone, so that the water flow in the tank produces a horizontal cyclone perpendicular to the mainstream, and then the sediment in the water body is sunk into the sedimentation tank 27, and then discharged from the discharge port 29 through the electric feeding screw 28. The water body entering the inclined tube clarification area subsequently forms a water body containing microbubble ozone with ozone and enters the desulfurization tower 1 for further desulfurization treatment. After the desulfurization treatment, the water body is passed through ozone for cyclone sedimentation, and then microbubbles are generated by ozone. The bubble space in the microbubble solution itself will produce a variety of active free radicals (hydroxyl ions, active oxygen ions, hydrogen ions, etc.), among which the hydroxyl ions have super strong oxidizing ability, thereby producing a certain desulfurization ability.

[0040] Step 5: After undergoing various treatment processes, the flue gas passes through the demister 16 and is discharged to the outside of the desulfurization tower 1 through the induced draft fan 15.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions should also be deemed to fall within the protection scope of the technical solution of the present invention.

Claims

1. A seawater desulfurization method for large ships, characterized in that: The device includes a desulfurization tower, a seawater lifting pump, a flue gas heat exchanger, a cyclone sedimentation tank and a microbubble generator. The top of the desulfurization tower is provided with a flue gas outlet, the bottom is provided with a drain port, the inside of the desulfurization tower is provided with an air inlet above the drain port, the air inlet is connected to the air flow section of the flue gas heat exchanger, the inside of the desulfurization tower is provided with a first spray pipe near the upper end of the air inlet, the first spray pipe is connected to a stirring tank, the front end of the stirring tank is connected to the liquid flow section of the flue gas heat exchanger, the inside of the desulfurization tower is provided with two layers of cyclone atomizers above the first spray pipe, the upper layer of the cyclone atomizer is connected to the upper layer of the cyclone atomizer. The desulfurization tower is connected to the seawater lifting pump, the bottom discharge port of the desulfurization tower is connected to the water inlet of the cyclone sedimentation tank, the water outlet of the cyclone sedimentation tank is connected to the microbubble generator, and the microbubble generator is respectively connected to the cyclone atomizer in the lower layer. A dielectric barrier low-temperature plasma reactor is provided above the cyclone atomizer in the desulfurization tower, a second spray pipe is provided above the dielectric barrier low-temperature plasma reactor, and the second spray pipe is connected to the feed pump outside the desulfurization tower, an induced draft fan is provided at the flue gas outlet, and a demister is provided below the flue gas outlet in the desulfurization tower. The connecting pipe between the first spray pipe and the stirring tank is provided with a thermometer, a first stop valve and a feeding pump; A second stop valve is provided at the connection between the air inlet and the air flow section of the flue gas heat exchanger; A fourth stop valve is also provided between the seawater lifting pump and the upper cyclone atomizer; One end of the microbubble generator is also connected to an ozone generator; An aeration pipe is provided in the cyclone sedimentation tank, the aeration pipe is connected to the ozone generator, the aeration direction of the aeration pipe is arranged in a tangential direction with respect to the inner wall of the cyclone sedimentation tank, a sedimentation tank is provided at the bottom of the cyclone sedimentation tank, an electric feeding screw is provided in the sedimentation tank, a discharge port is provided at the outlet end of the electric feeding screw on one side of the cyclone sedimentation tank, an electric gate valve is provided at the discharge port, a partition is provided on the side of the cyclone sedimentation tank away from the aeration pipe, and an inclined tube clarification zone is separated from the other side of the cyclone sedimentation tank away from the aeration pipe by the partition; The method comprises the following steps: Step 1: First, open the second stop valve and the fourth stop valve. The flue gas generated by the ship enters the desulfurization tower and comes into contact with the seawater output by the cyclone atomizer to achieve preliminary treatment. Step 2: The dielectric barrier low-temperature plasma reactor is turned on to release the low-temperature plasma. At the same time, the feed pump is turned on to spray ethanolamine from above the dielectric barrier low-temperature plasma reactor through the second spray pipe. The desulfurization reaction of the flue gas is achieved through the combination of ethanolamine and the plasma environment. Step 3: When the flue gas heat exchanger reaches the preset operating temperature, water is introduced. After the water is heated by the flue gas heat exchanger, it enters the mixing tank. Urea is added to the mixing tank while stirring. When the urea solution reaches the preset initial temperature, the first stop valve is opened to exchange heat with the high-temperature flue gas at the air inlet through the feeding pump and achieve hydrolysis, thereby treating the high-temperature flue gas. Step 4: The water at the bottom of the desulfurization tower is discharged into the cyclone sedimentation tank. The ozone in the aeration pipe enters the cyclone sedimentation tank in the form of a cyclone, causing the water flow in the tank to generate a horizontal cyclone perpendicular to the main flow, thereby sinking the sediment in the water into the sedimentation tank. The sediment is then discharged from the discharge port through the electric feeding screw. The water entering the inclined tube clarification area subsequently reacts with ozone to form a water body containing microbubble ozone and enters the desulfurization tower for further desulfurization treatment. Step 5: After undergoing multiple treatment processes, the flue gas passes through the demister and is discharged to the outside of the desulfurization tower through the induced draft fan.

2. The seawater desulfurization method for large ships according to claim 1, characterized in that: A plurality of spray heads are evenly distributed on the first spray pipe and the second spray pipe.

3. The seawater desulfurization method for large ships according to claim 1, characterized in that: There are eight groups of cyclone atomizers in each layer, and the eight groups of cyclone atomizers are arranged in a tangential circular direction on the inner wall of the desulfurization tower.

4. The method for desulfurizing seawater for large ships according to claim 1, characterized in that: An electric stirrer is provided in the stirring tank.

5. The seawater desulfurization method for large ships according to claim 1, characterized in that: A third stop valve is provided between the feed pump and the second spray pipe.

6. The seawater desulfurization method for large ships according to claim 1, characterized in that: The inlet of the seawater lifting pump is communicated with the sea surface of the ship, and a replaceable filter is also provided at the inlet of the seawater lifting pump.

7. The seawater desulfurization method for large ships according to claim 1, characterized in that: A fifth stop valve is provided between the microbubble generator and the cyclone atomizer at the lower layer.

8. The seawater desulfurization method for large ships according to claim 1, characterized in that: The inclined tube clarification area is connected to the bottom of the cyclone sedimentation tank. Two groups of inclined tubes placed in opposite directions are arranged in the inclined tube clarification area. The inclined tubes have an inclination angle of 60°. The water outlet is arranged above the inclined tube clarification area.

9. The seawater desulfurization method for large ships according to claim 1, characterized in that: The control discharge current of the dielectric barrier low-temperature plasma reactor in step 2 is 0.83~4.16A, the discharge voltage is 0~20KV, the discharge frequency is 8.7kHz~11.0kHz, the discharge power is 8~90W, and the feed speed of ethanolamine is 2~3m 3 / h.

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