A desulfurization system and a method for sulfur dioxide absorption

Abstract

The present invention discloses a desulfurization system, comprising: a Venturi buffer tank, the gas inlet of the Venturi buffer tank is connected to the tail gas outlet, a Venturi valve and a check valve are arranged in the Venturi buffer tank, and a first gas outlet valve is installed on the gas outlet; the Venturi buffer tank is connected to a Venturi circulation pump through a pipeline; the Venturi circulation pump is connected to a primary falling film absorption tower, and the primary falling film absorption tower is further provided with a gas outlet, which is connected to the gas inlet of a secondary falling film absorption tower through a pipeline; the liquid caustic soda in the primary and secondary falling film absorption towers respectively flows into a primary water tank and a secondary water tank; a high gravity absorber is communicated with the secondary falling film absorption tower; the liquid caustic soda inlet of the desulfurization liquid caustic soda tank is connected to the liquid caustic soda outlet of the high gravity absorber; the waste gas in the high gravity absorber or the secondary falling film absorption tower is discharged through a desulfurization buffer tank. A method for absorbing sulfur dioxide is also disclosed. The present invention can absorb sulfur dioxide and eliminate the problem of salt accumulation in the tail gas pipeline and the Venturi buffer tank.

Description

Technical Field

[0001] The present invention relates to the field of waste gas treatment, and particularly to a desulfurization system and a method for absorbing sulfur dioxide. Background Art

[0002] In the reaction with thionyl chloride as the chlorinating agent, the by-product sulfur dioxide is neutralized with liquid caustic soda in the desulfurization system to generate sodium bisulfite wastewater, which is sent out for treatment. The tail gas containing a large amount of sulfur dioxide in the original system passes through a Venturi buffer tank, a rotating packed bed, a desulfurization buffer tank (spare), and finally enters the rooftop absorption device.

[0003] Among them, the absorption capacity of the Venturi buffer tank is small, and the desulfurization buffer tank has poor absorption effect and large odor, and is only used when the rotating packed bed fails. During this process, salts are likely to accumulate in the Venturi buffer tank and the tail gas pipeline, posing a safety hazard; the rotating packed bed, as the main desulfurization device, is in a high-acidity and high-temperature working condition environment for a long time, resulting in equipment corrosion and frequent failures, affecting normal production. Summary of the Invention

[0004] In order to overcome the above problems, one of the purposes of the present invention is to provide a desulfurization system that can stably absorb a large amount of sulfur dioxide in waste gas under high-acidity and high-temperature conditions.

[0005] Another purpose of the present invention is to provide a method for absorbing sulfur dioxide in waste gas using the above desulfurization system.

[0006] A desulfurization system includes:

[0007] At least one Venturi buffer tank, the gas inlet of the Venturi buffer tank is connected to the tail gas outlet, a Venturi valve and a check valve are arranged in the Venturi buffer tank, and a first gas outlet valve is installed on the gas outlet;

[0008] The Venturi buffer tank is connected to a Venturi circulation pump through a pipeline;

[0009] The outlet of the Venturi circulation pump is connected to the gas inlet of the first-stage falling film absorption tower, and the first-stage falling film absorption tower is also provided with a gas outlet, which is connected to the gas inlet of the second-stage falling film absorption tower through a pipeline;

[0010] The first-stage and second-stage falling film absorption towers are respectively provided with a first and a second liquid caustic soda inlet and outlet, and a first and a second cooling water inlet and outlet;

[0011] The lower parts of the first-stage and second-stage falling film absorption towers are respectively connected to a first-stage water tank and a second-stage water tank;

[0012] The primary water tank and the secondary water tank are respectively provided with a first and a second water tank feed inlet, a first and a second liquid caustic soda inlet and outlet. The liquid caustic soda in the primary and secondary falling film absorbers respectively flows into the primary water tank and the secondary water tank;

[0013] At least one high gravity absorber, which is connected to the gas outlet of the secondary falling film absorber through a pipeline;

[0014] At least one desulfurization liquid caustic soda tank, the liquid caustic soda inlet of which is connected to the liquid caustic soda outlet of the high gravity absorber;

[0015] The waste gas in the high gravity absorber or the secondary falling film absorber is discharged through a desulfurization buffer tank.

[0016] In a preferred embodiment of the present invention, the primary water tank and the secondary water tank respectively pump the liquid caustic soda into the primary and secondary falling film absorbers through a primary liquid caustic soda circulation pump and a secondary liquid caustic soda circulation pump.

[0017] In a preferred embodiment of the present invention, the liquid caustic soda outlet of the desulfurization liquid caustic soda tank is connected to the liquid caustic soda inlet of the high gravity absorber through a high gravity circulation pump.

[0018] In a preferred embodiment of the present invention, the outlet of the desulfurization buffer tank is connected to a roof absorption device through a blower.

[0019] In a preferred embodiment of the present invention, a discharge valve is provided at the bottom of the venturi buffer tank.

[0020] In a preferred embodiment of the present invention, the components are connected to each other through pipelines with valves.

[0021] In a preferred embodiment of the present invention, the primary falling film absorber and the secondary falling film absorber are connected in series.

[0022] In a preferred embodiment of the present invention, the high gravity absorber is provided with a gas inlet and outlet, a liquid caustic soda inlet and outlet.

[0023] A sulfur dioxide absorption method includes the following steps:

[0024] Step 1: First start the venturi circulation pump and then start the high gravity absorber, and increase the rotation speed in sequence according to the ratios of 30%, 50%, and 100%. After running smoothly, start the high gravity circulation pump;

[0025] Step 2: Open the venturi valve, and then start the blower, and the tail gas enters the desulfurization system;

[0026] Subsequently, according to the total amount of tail gas absorption in each batch, the sodium hydroxide solution is pumped into the high-gravity absorber, the first-stage falling film absorber, the second-stage falling film absorber, and the Venturi buffer tank.

[0027] In a preferred embodiment of the present invention, in the second step, the gas inlet mode of the first-stage falling film absorber and the second-stage falling film absorber is from top to bottom. If the pipeline for entering the absorption water tank is blocked, the absorption liquid enters the desulfurization high-gravity from the gas outlet pipeline, with low safety hazards.

[0028] Due to the adoption of the above technical solution, the present invention can absorb sulfur dioxide, eliminate the problem of salt accumulation in the tail gas pipeline and the Venturi buffer tank, and improve its safety; reduce the usage amount of liquid caustic soda and the amount of wastewater treatment, effectively reduce the desulfurization cost; at the same time, reduce the load of the desulfurization high-gravity, reduce the equipment failure rate, save the maintenance cost, and ensure the production progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the present invention.

[0030] Figure 2 It is a schematic diagram of the inlet and outlet temperatures of the high-gravity gas phase. DETAILED DESCRIPTION OF THE INVENTION

[0031] See Figure 1 , the desulfurization system 100 shown in the figure includes a Venturi buffer tank 110, a Venturi circulation pump 120, two falling film absorbers (the first-stage falling film absorber 130 and the second-stage falling film absorber 140 respectively), two water tanks (the first-stage water tank 150 and the second-stage water tank 160 respectively), two liquid caustic soda circulation pumps (the first-stage liquid caustic soda circulation pump 170 and the second-stage liquid caustic soda circulation pump 180 respectively), a high-gravity absorber 190, a desulfurization liquid caustic soda tank 200, a high-gravity circulation pump 210, a desulfurization buffer tank 220, and a blower 230.

[0032] The Venturi buffer tank 110 is provided with a Venturi valve, a check valve, a gas outlet, and a gas outlet valve (not shown in the figure), and a discharge valve (not shown in the figure) is provided at the bottom of the Venturi buffer tank 110.

[0033] The inlet of the Venturi circulation pump 120 is connected to the discharge valve of the Venturi buffer tank 110 through a pipeline.

[0034] The tops of the first-stage falling film absorber 130 and the second-stage falling film absorber 140 are respectively provided with a gas inlet 131 and 141, a liquid caustic soda inlet 132 and 142, a liquid caustic soda inlet valve 133 and 143, and a cooling water outlet 134 and 144.

[0035] The bottoms are respectively provided with a gas outlet 135 and 145, a liquid caustic soda outlet 136 and 146, a liquid caustic soda outlet valve 137 and 147, and a cooling water inlet 138 and 148.

[0036] The gas outlet 135 at the bottom of the first-stage falling film absorption tower 130 is connected to the gas inlet 141 of the second-stage falling film absorption tower 140 through a pipeline.

[0037] Two water tanks (the first-stage water tank 150 and the second-stage water tank 160 respectively) are provided with feed inlets 151 and 161, liquid caustic soda inlets 152 and 162, and liquid caustic soda outlets 153 and 163. The liquid caustic soda inlet 152 of the first-stage water tank 150 is connected to the liquid caustic soda outlet valve 137 of the first-stage falling film absorption tower 130 through a pipeline.

[0038] The liquid caustic soda inlet 162 of the second-stage water tank 160 is connected to the liquid caustic soda outlet valve 147 of the second-stage falling film absorption tower 140 through a pipeline.

[0039] Two liquid caustic soda circulation pumps (the first-stage liquid caustic soda circulation pump 170 and the second-stage liquid caustic soda circulation pump 180 respectively). The inlet of the first-stage liquid caustic soda circulation pump 170 is connected to the liquid caustic soda outlet 153 valve of the first-stage water tank 150 through a pipeline, and the outlet of the first-stage liquid caustic soda circulation pump 170 is connected to the liquid caustic soda inlet valve 133 of the first-stage falling film absorption tower 130 through a pipeline.

[0040] The inlet of the second-stage liquid caustic soda circulation pump 180 is connected to the liquid caustic soda outlet 163 valve of the second-stage water tank 160 through a pipeline, and the outlet of the second-stage liquid caustic soda circulation pump 180 is connected to the liquid caustic soda inlet valve 143 of the second-stage falling film absorption tower 140 through a pipeline.

[0041] The rotating packed bed absorber 190 is provided with a gas inlet 191, a gas inlet valve 192, a gas outlet 193, a gas outlet valve 194, a liquid caustic soda inlet 195, a liquid caustic soda inlet valve 196, a liquid caustic soda outlet 197, and a liquid caustic soda outlet valve 198.

[0042] The gas inlet valve 192 is connected to the gas outlet 145 of the second-stage falling film absorption tower 140 through a pipeline. The desulfurization liquid caustic soda tank 200 is provided with a liquid caustic soda inlet 201, a liquid caustic soda outlet 202, and a liquid caustic soda outlet valve 203. The liquid caustic soda inlet 201 of the desulfurization liquid caustic soda tank 200 is connected to the liquid caustic soda outlet valve 198 of the rotating packed bed absorber 190 through a pipeline.

[0043] The inlet of the rotating packed bed circulation pump 210 is connected to the liquid caustic soda outlet valve 203 of the desulfurization liquid caustic soda tank 200 through a pipeline, and the outlet of the rotating packed bed circulation pump 210 is connected to the liquid caustic soda inlet valve 196 of the rotating packed bed absorber 190 through a pipeline.

[0044] The desulfurization buffer tank 220 is provided with a gas inlet 221 and a gas outlet 222; the gas inlet 221 of the desulfurization buffer tank 220 is connected to the gas outlet valve 194 of the rotating packed bed absorber 190 through a pipeline; the gas inlet 221 of the desulfurization buffer tank 220 is connected to the gas outlet 145 of the second-stage falling film absorption tower 140 through a pipeline, and a gas inlet valve can be provided.

[0045] The inlet 231 of the blower 230 is connected to the gas outlet 222 of the desulfurization buffer tank 220 through a pipeline; the outlet 232 of the blower 230 is connected to the roof absorption device 240.

[0046] To improve the absorption effect, the first-stage falling film absorption tower and the second-stage falling film absorption tower can be connected in series.

[0047] The following takes the absorption of sulfur dioxide as an example to illustrate in detail the method for absorbing sulfur dioxide using the above desulfurization system in the present invention. This method includes the following steps:

[0048] (1) Start the Venturi circulation pump, the first-stage liquid caustic soda circulation pump, and the second-stage liquid caustic soda circulation pump. Start the rotating packed bed absorber (when starting, increase the rotation speed in sequence of 30%, 50%, 100%), and start the rotating packed bed circulation pump after running smoothly.

[0049] (2) Open the Venturi valve, and then start the blower to make the tail gas enter the absorption system.

[0050] (3) According to the total amount of tail gas absorbed in each batch, add sodium hydroxide solution to the rotating packed bed absorber, the first-stage falling film absorption tower, the second-stage falling film absorption tower, and the Venturi buffer tank.

[0051] After adding two falling film absorption towers to the original process in the new process, the highest temperature at the inlet of the rotating packed bed absorber drops from 80 °C in the original process to 50 °C, and the outlet temperature drops from 40 °C in the original process to 20 °C. The temperature reduction ensures the normal operation of the rotating packed bed absorber.

[0052] In the present invention, the total amount of the absorption liquid is reduced. After each batch of materials in the first stage and the second stage of the new process is finished, it is pumped to the waste water tank. The absorption liquid in the rotating packed bed is changed every two batches. 600 kg of water in the Venturi is pumped to the second stage as the absorption liquid, and the remaining water and liquid caustic soda are supplemented. Calculated according to 800 batches per year, 392 tons of liquid caustic soda can be saved annually, and 880 tons of waste water can be reduced.

[0053] Table 1 shows the ratio of the absorption liquid:

[0054]

[0055] To reduce potential safety hazards, the gas inlet mode of the first-stage falling film absorption tower and the second-stage falling film absorption tower is from top to bottom. If the pipeline for entering the absorption water tank is blocked, the absorption liquid enters the desulfurization rotating packed bed from the gas outlet pipeline, and the potential safety hazard is low.

Claims

1. A desulfurization system, characterized in that, It is characterized in that it includes: At least one Venturi buffer tank, the gas inlet of the Venturi buffer tank is connected to the tail gas outlet, a Venturi valve and a check valve are arranged in the Venturi buffer tank, and a first gas outlet valve is installed on the gas outlet; The Venturi buffer tank is connected to a Venturi circulation pump through a pipeline; The outlet of the Venturi buffer tank is connected to the gas inlet of the first-stage falling film absorption tower, and the first-stage falling film absorption tower is also provided with a gas outlet, which is connected to the gas inlet of the second-stage falling film absorption tower through a pipeline; The first-stage and second-stage falling film absorption towers are respectively provided with first and second liquid caustic soda inlets and outlets, and first and second cooling water inlets and outlets; The lower parts of the first-stage and second-stage falling film absorption towers are respectively connected to a first-stage water tank and a second-stage water tank; The first-stage and second-stage water tanks are respectively provided with first and second water tank feed inlets, first and second liquid caustic soda inlets and outlets, and the liquid caustic soda in the first-stage and second-stage falling film absorption towers respectively flows into the first-stage and second-stage water tanks; At least one high-gravity absorber, the high-gravity absorber is connected to the gas outlet of the second-stage falling film absorption tower through a pipeline; At least one desulfurization liquid caustic soda tank, the liquid caustic soda inlet of the desulfurization liquid caustic soda tank is connected to the liquid caustic soda outlet of the high-gravity absorber; the liquid caustic soda outlet of the desulfurization liquid caustic soda tank is connected to the liquid caustic soda inlet of the high-gravity absorber through a high-gravity circulation pump; The waste gas in the high-gravity absorber or the second-stage falling film absorption tower is discharged through a desulfurization buffer tank, and the outlet of the desulfurization buffer tank is connected to a roof absorption device through a fan.

2. The desulfurization system according to claim 1, characterized in that, The first-stage and second-stage water tanks respectively pump the liquid caustic soda into the first-stage and second-stage falling film absorption towers through a first-stage liquid caustic soda circulation pump and a second-stage liquid caustic soda circulation pump.

3. A desulfurization system according to claim 1, characterized in that, A discharge valve is arranged at the bottom of the Venturi buffer tank.

4. A desulfurization system according to claim 1, characterized in that, The first-stage falling film absorption tower and the second-stage falling film absorption tower are connected in series.

5. A desulfurization system according to claim 1, characterized in that, The high-gravity absorber is provided with a gas inlet and outlet, a liquid caustic soda inlet and outlet.

6. A method for sulfur dioxide absorption using the system according to any one of claims 1-5, characterized in that, It includes the following steps: Step 1: First start the Venturi circulation pump and then start the high-gravity absorber, and increase the rotation speed in sequence according to the ratios of 30%, 50%, and 100%. After running smoothly, start the high-gravity circulation pump; Step 2: Open the Venturi valve, and then start the fan, and the tail gas enters the desulfurization system; After that, according to the total amount of tail gas absorption in each batch, pump the sodium hydroxide solution into the high-gravity absorber, the first-stage falling film absorption tower, the second-stage falling film absorption tower and the Venturi buffer tank.

7. The sulfur dioxide absorption method according to claim 6, wherein In Step 2, the gas inlet mode of the first-stage falling film absorption tower and the second-stage falling film absorption tower is from top to bottom. If the pipelines for entering the first-stage water tank and the second-stage water tank are blocked, the absorption liquid enters the high-gravity absorber from the gas outlet pipelines of the first-stage falling film absorption tower and the second-stage falling film absorption tower, and the potential safety hazard is low.

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