Ship tail gas desulfurization and denitrification catalytic treatment device and method

Abstract

The invention discloses a ship tail gas desulfurization and denitration catalytic treatment device and method.The device comprises a heat exchange oil tank, a desulfurization tower, a denitration tower and an SCR denitration reactor, a first heat exchange coil pipe is arranged in the heat exchange oil tank, and a tail gas exhaust pipe of a ship diesel engine is connected with a three-way valve; one outlet of the three-way valve is connected with a first heat exchange coil pipe through a pipeline, the other outlet of the three-way valve is connected with a heat exchanger through a pipeline, the heat exchanger and the first heat exchange coil pipe are connected with an air inlet header pipe of a desulfurizing tower through pipelines, and a plurality of first spraying heads are arranged in the desulfurizing tower and connected with a first booster pump through pipelines; the first booster pump is connected with an alkali liquor tank through a pipeline; the bottom of the desulfurizing tower is communicated with an alkali liquor recycling tank through a pipeline. Compared with a traditional treatment mode that sulfur dioxide and nitric oxide need to be completely oxidized into sulfur trioxide and nitrogen dioxide, the method only needs to oxidize part of nitric oxide, energy is saved, and meanwhile treatment reagents can be saved.

Description

Technical Field

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

[0002] Heavy fuel oil is a common fuel for marine diesel engines. After burning, heavy fuel oil will produce a large amount of harmful gases. The harmful gas components are NOx (mainly NO) and SOx (mainly SO2). These gases are prone to cause acid rain and photochemical smog, which are harmful to human health and the environment. To this end, the International Maritime Organization has formulated a series of anti-pollution conventions to strictly limit the emission of harmful components in ship exhaust. At the same time, various countries are also actively developing ship exhaust treatment devices to treat NOx and SOx in exhaust gas. The main methods for removing sulfur oxides include ammonia method, organic amine method, wet calcium method, sodium alkali method, citrate method, etc. The main methods for removing nitrogen oxides include selective catalytic reduction method, selective non-catalytic reduction method, non-selective catalytic reduction method, etc. Most of the existing desulfurization and denitrification devices have the problems of high energy consumption, large reagent usage, and large space occupation. Summary of the invention

[0003] In view of the above technical problems, the present invention provides a catalytic treatment device and method for desulfurization and denitrification of ship exhaust.

[0004] Technical solution: A ship exhaust desulfurization and denitration catalytic treatment device comprises a heat exchange oil tank, a desulfurization tower, a denitration tower and an SCR denitration reactor, wherein a first heat exchange coil is arranged in the heat exchange oil tank, an exhaust emission pipe of a ship diesel engine is connected to a three-way valve, one outlet of the three-way valve is connected to the first heat exchange coil through a pipeline, another outlet of the three-way valve is connected to the heat exchanger through a pipeline, the heat exchanger and the first heat exchange coil are connected to an air intake manifold of the desulfurization tower through a pipeline, a plurality of first spray heads are arranged inside the desulfurization tower, the first spray head is connected to a first booster pump through a pipeline, the first booster pump is connected to an alkali liquid tank through a pipeline, the bottom of the desulfurization tower is connected to an alkali liquid recovery tank through a pipeline, the top air outlet of the desulfurization tower is connected to a plasma oxidation device through a pipeline, and the plasma oxidation device An air outlet is connected to an air inlet of a denitrification tower through a pipeline, a plurality of second spray heads are arranged inside the denitrification tower, the second spray heads are connected to a second booster pump through a pipeline, the second booster pump is connected to an alkali solution recovery tank through a pipeline, an air outlet at the top of the denitrification tower is connected to a second heat exchange coil through a pipeline, the second heat exchange coil is arranged in a heat exchange oil tank, the second heat exchange coil is connected to one of the air inlets of a gas mixer through a pipeline, the other air inlet of the gas mixer is connected to a third heat exchange coil through a pipeline, the third heat exchange coil is arranged in the heat exchange oil tank, the third heat exchange coil is connected to an ammonia generator through a pipeline, the end outlet of the gas mixer is connected to an air inlet of an SCR denitrification reactor, and a porous carrier loaded with a catalyst is arranged inside the SCR denitrification reactor.

[0005] Furthermore, a dust removal device is provided between the exhaust pipe of the ship diesel engine and the three-way valve to remove solid particles in the ship exhaust.

[0006] Furthermore, the alkali solution in the alkali solution box includes 5-10% sodium hydroxide solution and 10-20% sodium carbonate solution, and the added amount of the sodium carbonate solution is 5-15% of the sodium hydroxide solution.

[0007] Furthermore, a packing layer is provided in the tower body between the air inlet of the desulfurization tower and the denitration tower and the first spray head or the second spray head, so as to increase the contact time between the gas and the liquid.

[0008] Furthermore, the alkali liquid tank and the alkali liquid recovery tank are both provided with pH sensors, the alkali liquid recovery tank is also connected to a reflux pump through a pipeline, and the reflux pump is connected to the first spray head through a reflux pipe.

[0009] Furthermore, a gas buffer tank is provided between the plasma oxidation device and the denitration tower, and a flow regulating valve is provided between the gas buffer tank and the denitration tower.

[0010] Furthermore, the alkali liquid box and the alkali liquid recovery box are both provided with solid feeders, and both are provided with stirrers inside; and a water inlet is also provided on the top of the alkali liquid box.

[0011] Furthermore, the bottom of the denitrification tower is connected to a waste liquid treatment tank through a pipeline, and an oil-water separation component and a sedimentation separation component are arranged in the waste liquid treatment tank.

[0012] Furthermore, the heat exchange oil tank is provided with a temperature controller.

[0013] A catalytic treatment method for desulfurization and denitrification of ship exhaust gas comprises the following steps: S1: The exhaust gas of the ship diesel engine is passed through the dust removal device to remove solid particles. After dust removal, the exhaust gas is controlled by the three-way valve. The exhaust gas first passes through the first heat exchange coil and the intake manifold to enter the desulfurization tower. The high-temperature exhaust gas heats the heat transfer oil in the heat exchange oil tank through the first heat exchange coil. The temperature controller controls the temperature after heating. The exhaust gas enters the desulfurization tower for desulfurization after heat exchange and cooling. When the temperature of the heat transfer oil reaches the set temperature, the other exhaust gas enters the desulfurization tower after being cooled through the heat exchanger; S2: After the tail gas enters the desulfurization tower, it moves upward from the air inlet below the desulfurization tower. At the same time, the first booster pump works to spray the alkali in the alkali tank from the first spray head. The sulfur dioxide in the tail gas meets the alkali to generate sodium sulfite, and a small amount of nitrogen dioxide meets the alkali to generate sodium nitrate and sodium nitrite; the tail gas after desulfurization treatment enters the plasma oxidation device, and the alkali that absorbs sulfur dioxide enters the alkali recovery tank. The pH sensor detector on the alkali recovery tank monitors the alkaline strength of the internal recovery liquid. If the alkaline strength is high, it can be refluxed for reuse. At this time, the reflux pump is started to continue to absorb sulfur dioxide; S3: The plasma oxidation device works to partially oxidize the residual nitric oxide in the tail gas into nitrogen dioxide. The oxidized tail gas can enter the gas buffer tank for temporary storage. When the pH value of the alkali solution recovery tank does not meet the requirements for reflux use, sodium sulfite is added to the alkali solution recovery tank to adjust the total concentration of sodium sulfite in the recovery liquid; S4: The flow regulating valve controls the flow of the exhaust gas into the denitrification tower. After the exhaust gas enters the denitrification tower, the second booster pump pumps the liquid in the alkali solution recovery tank into the second spray head. The sodium sulfite in the liquid reacts with the nitrogen dioxide and nitric oxide in the exhaust gas to generate nitrogen and water. The ratio of the reacted nitric oxide to nitrogen dioxide is 1:1. S5: After the reaction is completed, the small amount of nitrogen monoxide remaining in the exhaust gas is heated in the heat exchange oil tank and mixed with the ammonia that has been heated in the same way, and then enters the SCR denitrification reactor, where it completely reacts to generate nitrogen and water under the catalytic action of the catalyst.

[0014] Beneficial effects: The present invention provides a ship exhaust desulfurization and denitration catalytic treatment device and method, the device absorbs the heat of the ship diesel engine exhaust through a heat exchange oil tank and cools it, and after cooling, it enters the desulfurization tower, plasma oxidation device, denitration tower and SCR denitration reactor in sequence for treatment, wherein the denitration tower reuses the recovered alkali solution of the desulfurization tower, and the sodium sulfite in the recovered alkali solution reacts with the nitrogen monoxide and nitrogen dioxide in the exhaust gas. Compared with the traditional treatment method, sulfur dioxide and nitrogen monoxide need to be completely oxidized into sulfur trioxide and nitrogen dioxide. The present invention only needs to oxidize part of the nitrogen monoxide, which can save energy and treatment reagents. At the same time, the remaining unoxidized nitrogen monoxide in the exhaust gas reacts with the heated ammonia after being heated by the heat exchange oil tank, and the heat exchange oil tank provides energy for the SCR reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the catalytic treatment device for desulfurization and denitrification of ship exhaust gas according to the present invention. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0017] Example: As attached Figure 1 As shown, a ship exhaust desulfurization and denitration catalytic treatment device comprises a heat exchange oil tank 1, a desulfurization tower 2, a denitration tower 3 and an SCR denitration reactor 4, a first heat exchange coil 5 is arranged in the heat exchange oil tank 1, an exhaust emission pipe of a ship diesel engine is connected to a three-way valve 5, one outlet of the three-way valve 5 is connected to the first heat exchange coil 5 through a pipeline, the other outlet of the three-way valve 5 is connected to a heat exchanger 6 through a pipeline, the heat exchanger 6 and the first heat exchange coil 5 are connected to an air intake manifold 7 of the desulfurization tower 2 through a pipeline, a plurality of first spray heads 8 are arranged inside the desulfurization tower 2, the first spray head 8 is connected to a first booster pump 9 through a pipeline, the first booster pump 9 is connected to an alkali liquid tank 10 through a pipeline, the bottom of the desulfurization tower 2 is connected to an alkali liquid recovery tank 11 through a pipeline, the top air outlet of the desulfurization tower 2 is connected to a plasma oxidation device 12 through a pipeline, the outlet of the plasma oxidation device 12 The air port is connected to the air inlet of the denitrification tower 3 through a pipeline. A plurality of second spray heads 13 are arranged inside the denitrification tower 3. The second spray head 13 is connected to the second booster pump 14 through a pipeline. The second booster pump 14 is connected to the alkali solution recovery tank 11 through a pipeline. The top air outlet of the denitrification tower 3 is connected to the second heat exchange coil 15 through a pipeline. The second heat exchange coil 15 is placed in the heat exchange oil tank 1. The second heat exchange coil 15 is connected to one of the air inlets of the gas mixer 16 through a pipeline. The other air inlet of the gas mixer 16 is connected to the third heat exchange coil 17 through a pipeline. The third heat exchange coil 17 is placed in the heat exchange oil tank 1. The third heat exchange coil 17 is connected to the ammonia generator 18 through a pipeline. The end outlet of the gas mixer 16 is connected to the air inlet of the SCR denitrification reactor 4. A porous carrier loaded with a catalyst is arranged inside the SCR denitrification reactor 4.

[0018] A dust removal device 19 is provided between the exhaust pipe of the ship's diesel engine and the three-way valve 5 to remove solid particles in the ship's exhaust gas. Specifically, an electrostatic precipitator or a cyclone may be used.

[0019] The alkali solution in the alkali solution box 10 includes 5-10% sodium hydroxide solution and 10-20% sodium carbonate solution, and the amount of sodium carbonate solution added is 5-15% of the sodium hydroxide solution. The reactions occurring in the desulfurization tower include: (1) sulfur dioxide reacts with sodium hydroxide to form sodium sulfite; (2) a small amount of nitrogen dioxide in the tail gas reacts with sodium hydroxide to form sodium nitrate and sodium nitrite; (3) carbon dioxide in the tail gas reacts with sodium hydroxide to form sodium carbonate. In order to reduce the occurrence of this reaction, sodium carbonate is added to inhibit the reaction.

[0020] A packing layer 20 is provided in the tower body between the air inlet of the desulfurization tower 2 and the denitration tower 3 and the first spray head 8 or the second spray head 13 to increase the contact time between the gas and the liquid. After the liquid is sprayed out from the spray head, it contacts and reacts with the rising airflow, falls to the packing layer, slowly flows down through the surface of the packing layer, and reacts with sulfur dioxide or nitrogen dioxide in the gas.

[0021] The alkali liquid tank 10 and the alkali liquid recovery tank 11 are both provided with pH sensors. The alkali liquid recovery tank 11 is also connected to the reflux pump 21 through a pipeline, and the reflux pump 21 is connected to the first spray head 8 through a reflux pipe. The pH sensor monitors the pH value of the liquid in the alkali liquid tank 10 and the alkali liquid recovery tank 11. When the pH in the alkali liquid recovery tank 11 shows that the alkalinity is strong, the reflux pump 21 is started for reflux use.

[0022] A gas buffer tank 22 is also provided between the plasma oxidation device 12 and the denitrification tower 3, and a flow regulating valve 23 is provided between the gas buffer tank 22 and the denitrification tower 3. Since the absorption liquid of the denitrification tower 3 uses the recovered liquid in the alkali recovery tank 11, and the recovered liquid in the alkali recovery tank 11 needs to be refluxed when the alkalinity is strong, for this reason, the gas buffer tank 22 is designed to temporarily store the tail gas treated by the desulfurization tower 2, and when reflux is not required, the recovered liquid in the alkali recovery tank 11 is pumped into the denitrification tower 3. The reaction occurring in the denitrification tower 3 is: sodium sulfite and nitric oxide and nitrogen dioxide undergo redox reaction to generate nitrogen and sodium sulfate, wherein the molar ratio of nitric oxide to nitrogen dioxide is 1:1.

[0023] The alkali liquid tank 10 and the alkali liquid recovery tank 11 are both provided with a solid feeder 24, and a stirrer 25 is provided inside; a water inlet is also provided at the top of the alkali liquid tank 10. Sodium hydroxide or sodium sulfite can be added through the solid feeder 24 to prepare the liquid or adjust the concentration of sodium sulfite in the recovered liquid in the alkali liquid recovery tank 11.

[0024] The bottom of the denitrification tower 3 is connected to the waste liquid treatment box 26 through a pipeline. The waste liquid treatment box 26 is provided with an oil-water separation component and a sedimentation separation component for separating the oil on the surface and the sediment on the bottom. The middle layer liquid is discharged normally.

[0025] The heat exchange oil tank 1 is provided with a temperature controller 27 for controlling the temperature of the heat transfer oil in the heat exchange oil phase 1. When the temperature is low, it is heated by the tail gas. When it is too high, the tail gas is passed through the heat exchanger 6 to complete energy recovery and reuse.

[0026] A catalytic treatment method for desulfurization and denitrification of ship exhaust gas comprises the following steps: S1: The exhaust gas of the ship diesel engine is passed through the dust removal device 19 to remove solid particles. After the dust removal, the exhaust gas is controlled by the three-way valve 5. The exhaust gas first passes through the first heat exchange coil 5 and the intake manifold 7 to enter the desulfurization tower 2. The high-temperature exhaust gas heats the heat transfer oil in the heat exchange oil tank 1 through the first heat exchange coil 5. The temperature controller 27 controls the temperature after heating. After the exhaust gas is cooled by heat exchange, it enters the desulfurization tower 2 for desulfurization. When the temperature of the heat transfer oil reaches the set temperature, the other exhaust gas is cooled by the heat exchanger 6 and then enters the desulfurization tower 2; S2: After the tail gas enters the desulfurization tower 2, it moves upward from the air inlet below the desulfurization tower 2. At the same time, the first booster pump 9 works to spray the alkali solution in the alkali solution tank 10 from the first spray head 8. The sulfur dioxide in the tail gas meets the alkali to generate sodium sulfite, and a small amount of nitrogen dioxide meets the alkali to generate sodium nitrate and sodium nitrite; the tail gas after desulfurization treatment enters the plasma oxidation device 12, and the alkali solution that absorbs sulfur dioxide enters the alkali solution recovery tank 11. The pH sensor detector on the alkali solution recovery tank 11 monitors the alkaline strength of the internal recovery liquid. If the alkaline strength is high, it can be refluxed for reuse. At this time, the reflux pump 21 is started to continue to absorb sulfur dioxide; S3: The plasma oxidation device 12 works to partially oxidize the residual nitric oxide in the tail gas into nitrogen dioxide. The oxidized tail gas can enter the gas buffer tank 22 for temporary storage. When the pH value of the alkali liquid recovery tank 11 does not meet the requirements for reflux use, sodium sulfite is added to the alkali liquid recovery tank 11 to adjust the total concentration of sodium sulfite in the recovered liquid; S4: The flow regulating valve 23 controls the flow of the exhaust gas entering the denitrification tower 3. After the exhaust gas enters the denitrification tower 3, the second booster pump 14 pumps the liquid in the alkali solution recovery tank 11 into the second spray head 13. The sodium sulfite in the liquid reacts with the nitrogen dioxide and nitrogen monoxide in the exhaust gas to generate nitrogen and water. The ratio of the reacted nitrogen monoxide to nitrogen dioxide is 1:1. S5: After the reaction is completed, a small amount of nitrogen monoxide remaining in the tail gas is heated in the heat exchange oil tank 1 and mixed with the ammonia that has been heated in the same manner, and then enters the SCR denitration reactor 4, where it is completely reacted to generate nitrogen and water under the catalytic action of the catalyst.

[0027] Although the present invention has been disclosed as above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone skilled in the art can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims of this application.

Claims

1. A catalytic treatment device for desulfurization and denitrification of ship exhaust, characterized in that: The invention comprises a heat exchange oil tank, a desulfurization tower, a denitration tower and an SCR denitration reactor, wherein a first heat exchange coil is arranged in the heat exchange oil tank, an exhaust emission pipe of a ship diesel engine is connected to a three-way valve, one outlet of the three-way valve is connected to the first heat exchange coil through a pipeline, another outlet of the three-way valve is connected to the heat exchanger through a pipeline, the heat exchanger and the first heat exchange coil are connected to an air intake manifold of the desulfurization tower through a pipeline, a plurality of first spray heads are arranged inside the desulfurization tower, the first spray head is connected to a first booster pump through a pipeline, the first booster pump is connected to an alkali liquid tank through a pipeline, the bottom of the desulfurization tower is connected to an alkali liquid recovery tank through a pipeline, the top air outlet of the desulfurization tower is connected to a plasma oxidation device through a pipeline, and the air outlet of the plasma oxidation device is connected to a plasma oxidation device through a pipeline. The pipeline is connected to the air inlet of the denitrification tower, a plurality of second spray heads are arranged inside the denitrification tower, the second spray head is connected to the second booster pump through a pipeline, the second booster pump is connected to the alkali solution recovery tank through a pipeline, the top air outlet of the denitrification tower is connected to the second heat exchange coil through a pipeline, the second heat exchange coil is placed in the heat exchange oil tank, the second heat exchange coil is connected to one of the air inlets of the gas mixer through a pipeline, the other air inlet of the gas mixer is connected to the third heat exchange coil through a pipeline, the third heat exchange coil is placed in the heat exchange oil tank, the third heat exchange coil is connected to the ammonia generator through a pipeline, the end outlet of the gas mixer is connected to the air inlet of the SCR denitrification reactor, and a porous carrier loaded with a catalyst is arranged inside the SCR denitrification reactor.

2. A ship exhaust desulfurization and denitrification catalytic treatment device according to claim 1, characterized in that: A dust removal device is provided between the exhaust gas discharge pipe of the ship diesel engine and the three-way valve, which is used to remove solid particles in the ship's exhaust gas.

3. A ship exhaust desulfurization and denitrification catalytic treatment device according to claim 1 or 2, characterized in that: The alkali solution in the alkali solution box includes 5-10% sodium hydroxide solution and 10-20% sodium carbonate solution, and the added amount of the sodium carbonate solution is 5-15% of the sodium hydroxide solution.

4. A catalytic treatment device for desulfurization and denitration of ship exhaust gas according to claim 3, characterized in that: A packing layer is provided in the tower body between the air inlet of the desulfurization tower and the denitration tower and the first spray head or the second spray head, so as to increase the contact time between the gas and the liquid.

5. A ship exhaust desulfurization and denitrification catalytic treatment device according to claim 4, characterized in that: The alkali liquid box and the alkali liquid recovery box are both provided with pH sensors. The alkali liquid recovery box is also connected to a reflux pump through a pipeline, and the reflux pump is connected to the first spray head through a reflux pipe.

6. A ship exhaust desulfurization and denitrification catalytic treatment device according to claim 1 or 5, characterized in that: A gas buffer tank is also provided between the plasma oxidation device and the denitration tower, and a flow regulating valve is provided between the gas buffer tank and the denitration tower.

7. A catalytic treatment device for desulfurization and denitration of ship exhaust gas according to claim 6, characterized in that: The alkali liquid box and the alkali liquid recovery box are both provided with solid feeders, and both are provided with stirring rods inside; and a water injection port is also provided on the top of the alkali liquid box.

8. A catalytic treatment device for desulfurization and denitration of ship exhaust gas according to claim 6, characterized in that: The bottom of the denitration tower is connected to a waste liquid treatment box through a pipeline, and an oil-water separation component and a sedimentation separation component are arranged in the waste liquid treatment box.

9. A catalytic treatment device for desulfurization and denitration of ship exhaust gas according to claim 8, characterized in that: The heat exchange oil tank is provided with a temperature controller.

10. A catalytic treatment method for desulfurization and denitrification of ship exhaust gas according to claim 9, characterized in that: The following steps are involved: S1: The exhaust gas of the ship diesel engine is passed through the dust removal device to remove solid particles. After dust removal, the exhaust gas is controlled by the three-way valve. The exhaust gas first passes through the first heat exchange coil and the intake manifold to enter the desulfurization tower. The high-temperature exhaust gas heats the heat transfer oil in the heat exchange oil tank through the first heat exchange coil. The temperature controller controls the temperature after heating. The exhaust gas enters the desulfurization tower for desulfurization after heat exchange and cooling. When the temperature of the heat transfer oil reaches the set temperature, the other exhaust gas enters the desulfurization tower after being cooled through the heat exchanger; S2: After the tail gas enters the desulfurization tower, it moves upward from the air inlet below the desulfurization tower. At the same time, the first booster pump works to spray the alkali in the alkali tank from the first spray head. The sulfur dioxide in the tail gas meets the alkali to generate sodium sulfite, and a small amount of nitrogen dioxide meets the alkali to generate sodium nitrate and sodium nitrite; the tail gas after desulfurization treatment enters the plasma oxidation device, and the alkali that absorbs sulfur dioxide enters the alkali recovery tank. The pH sensor detector on the alkali recovery tank monitors the alkaline strength of the internal recovery liquid. If the alkaline strength is high, it can be refluxed for reuse. At this time, the reflux pump is started to continue to absorb sulfur dioxide; S3: The plasma oxidation device works to partially oxidize the residual nitric oxide in the tail gas into nitrogen dioxide. The oxidized tail gas can enter the gas buffer tank for temporary storage. When the pH value of the alkali solution recovery tank does not meet the requirements for reflux use, sodium sulfite is added to the alkali solution recovery tank to adjust the total concentration of sodium sulfite in the recovery liquid; S4: The flow regulating valve controls the flow of the exhaust gas into the denitrification tower. After the exhaust gas enters the denitrification tower, the second booster pump pumps the liquid in the alkali solution recovery tank into the second spray head. The sodium sulfite in the liquid reacts with the nitrogen dioxide and nitric oxide in the exhaust gas to generate nitrogen and water. The ratio of the reacted nitric oxide to nitrogen dioxide is 1:

1. S5: After the reaction is completed, the small amount of nitrogen monoxide remaining in the exhaust gas is heated in the heat exchange oil tank and mixed with the ammonia that has been heated in the same way, and then enters the SCR denitrification reactor, where it completely reacts to generate nitrogen and water under the catalytic action of the catalyst.

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