Waste gas treatment system and waste gas treatment method

Abstract

The present invention discloses a waste gas treatment system and method, comprising: a waste gas treatment tower, a liquid caustic soda conveying device, a waste gas source storage tank, a liquid caustic soda circulation pump, a vacuum pump, and a program controller. Through the design of the waste gas treatment tower, the liquid caustic soda conveying device, the liquid caustic soda circulation pump, a first pH sensor, a second pH sensor, a third pH sensor, a spray liquid discharge pipe, and a program controller, as well as the design of treatment process conditions, the present invention can, on the one hand, ensure that waste gas is effectively absorbed and discharged harmlessly, and on the other hand, can monitor and adjust the pH value and pressure of the spray liquid in the waste gas treatment tower in real time and perform automatic feedback adjustment in a timely manner. This not only ensures efficient absorption of waste gas and improves waste gas treatment efficiency and quality, but also enables timely troubleshooting and control of blockages and other faults, reduces maintenance difficulty and cost, and promptly discharges the saturated solution obtained after spraying, recovers by-products, and realizes the transformation of waste into valuables.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a waste gas treatment system and a waste gas treatment method. Background Art

[0002] In today's society, chemical plants, steel mills, pharmaceutical plants, coking plants, and refineries still emit industrial waste gases from burning oil and coal, such as sulfuric acid dioxide and nitrogen oxides. If these gases are released into the atmosphere without treatment, they not only have a strong odor, seriously polluting the environment and affecting human health, but they can also interact with water vapor in the air, forming acid rain and causing secondary harm. Therefore, the effective collection and treatment of process waste gases is a key issue in current environmental protection.

[0003] However, the inventors of this application discovered during the process of implementing the technical solutions of the invention in the embodiments of this application that, although the existing waste gas treatment towers and waste gas treatment devices for waste gas treatment can treat waste gas to a certain extent and reduce waste gas emissions and the resulting harm, they still have the following problems:

[0004] 1. The pH value stability in the exhaust gas treatment device is low, the exhaust gas treatment efficiency is low, and the effect is poor;

[0005] 2. Existing waste gas treatment devices are prone to clogging and difficult to clear after clogging. The clearing process not only requires manual processing, but also increases wastewater discharge, resulting in large manpower input and secondary pollution of wastewater. Summary of the Invention

[0006] The present invention can solve the above-mentioned problems existing in the prior art by providing an exhaust gas treatment system and an exhaust gas treatment method.

[0007] In order to solve the above technical problems, the present invention provides an exhaust gas treatment system, comprising:

[0008] An exhaust gas treatment tower, comprising, from top to bottom, a tower top exhaust port, two or more tower sections, and a tower kettle; a spray liquid collection device is installed at the bottom of each tower section; the spray liquid collection device located at the topmost tower section is connected to a first pH value sensor, the spray liquid collection device located at the bottommost tower section is connected to a second pH value sensor and a spray liquid discharge pipe, and the tower kettle is connected to a third pH value sensor;

[0009] a liquid caustic soda conveying device, the liquid caustic soda conveying device being connected to the topmost tower section of the exhaust gas treatment tower through a pipeline with a first feeding valve, and being connected to the tower kettle through a pipeline with a second feeding valve;

[0010] A waste gas source storage tank, the waste gas source storage tank is connected to the tower kettle through an air inlet pipe;

[0011] a liquid caustic soda circulation pump, wherein the liquid inlet of the liquid caustic soda circulation pump is connected to the tower kettle through a pipeline, and the liquid outlet of the liquid caustic soda circulation pump is connected to the second tower section from top to bottom through a pipeline;

[0012] A vacuum pumping device, the vacuum pumping device being connected to the tower bottom;

[0013] A program controller, wherein the first pH sensor and the first feeding valve are connected through linkage control of the program controller; the second pH sensor and the spray liquid discharge valve on the spray liquid discharge pipe are connected through linkage control of the program controller; and the third pH sensor and the second feeding valve are connected through linkage control of the program controller.

[0014] In a preferred embodiment of the present invention, the ratio of the opening of the first feeding valve to the opening of the second feeding valve is 10% to 30%: 70% to 90%.

[0015] In a preferred embodiment of the present invention, the tower section is provided with fillers, and the spray liquid collecting device is located below the fillers; the spray liquid collecting device includes a spray liquid collector, a water collecting trough and a water distributor; wherein, the spray liquid collector is a corrugated folding guide plate, and its liquid outlet is located above the notch of the water collecting trough; the water collecting trough is an annular groove installed on the inner wall of the exhaust gas treatment tower; the water distributor includes a first transverse pipe, a vertical pipe, a second transverse pipe and a water distribution pipe, wherein the two ends of the first transverse pipe are connected to the inner ring wall of the water collecting trough, the second transverse pipe is located below the first transverse pipe, the two ends of the vertical pipe are connected to the first transverse pipe and the second transverse pipe respectively, the water distribution pipe is distributed in the second transverse pipe, and a water distribution hole is opened on it; the spray liquid discharge pipe is connected to the water collecting trough.

[0016] In a preferred embodiment of the present invention, the vacuum pumping device includes a water-flushing vacuum pump, a water-flushing pump head and a three-way valve. One end of the water-flushing vacuum pump is connected to the tower kettle, and the other end is connected to the three-way valve. The three-way valve is also connected to the air inlet pipe and the water-flushing pump head. The water outlet end of the water-flushing pump head extends into the tower kettle.

[0017] In a preferred embodiment of the present invention, the tower bottom is further equipped with a pressure sensor, and the pressure sensor is connected to the program controller.

[0018] In a preferred embodiment of the present invention, the tower bottom is also connected to a steam inlet pipe, the steam inlet pipe is provided with a steam inlet valve, a temperature sensor is also installed in the tower top exhaust port, and the steam inlet valve and the temperature sensor are connected through linkage control of the program controller.

[0019] In a preferred embodiment of the present invention, the topmost tower section is also connected to a cleaning water pipe, the cleaning water pipe is provided with a cleaning water valve, and the cleaning water pipe and the pressure sensor are connected through linkage control of the program controller.

[0020] To solve the above technical problems, the present invention provides a method for treating waste gas using the above waste gas treatment system, comprising the following steps:

[0021] (1) Waste gas absorption: The waste gas in the waste gas source storage tank is ejected into the waste gas treatment tower under negative pressure through the vacuum pumping device;

[0022] (2) Liquid caustic soda feeding: determining the delivery amount of liquid caustic soda according to the type and amount of the waste gas, and then delivering the required amount of liquid caustic soda to the waste gas treatment tower through the first feeding valve and the second feeding valve respectively, and regulating the opening of the first feeding valve and the second feeding valve according to the detection value of the first pH value sensor and the detection value of the third pH value sensor;

[0023] (3) Waste gas treatment: the liquid alkali with a mass concentration of 15-32% in the tower kettle is circulated and sprayed into the second tower section through the liquid alkali circulation pump to react with the waste gas, and the spray liquid after the reaction enters the spray liquid collecting device at the bottom of the tower section; when the second pH value sensor detects that the pH value of the spray liquid in the spray liquid collecting device is between 4.5 and 6, the spray liquid discharge valve is opened by the program controller to recover the spray liquid; when the second pH value sensor detects that the pH value of the spray liquid in the spray liquid collecting device is not between 4.5 and 6, the spray liquid discharge valve is in a closed state, and the spray liquid in the spray liquid collecting device is returned to the tower kettle to continue circulating and spraying, and the treated gas is discharged from the exhaust port at the top of the tower.

[0024] In a preferred embodiment of the present invention, in step (2), when the detection value of the first pH sensor is greater than 9, the opening of the first feeding valve is 10% to 30%; when the detection value of the third pH sensor is 7.5 to 8, the opening of the second feeding valve is 70% to 90%.

[0025] In a preferred embodiment of the present invention, it also includes a fault detection and processing step, and the fault detection and processing method is: when the program controller detects that the pressure value of the pressure sensor is greater than 0.1MPa, the cleaning water valve is opened to input cleaning water into the exhaust gas treatment tower until the pressure value of the pressure sensor recovers to 0~0.1MPa; when the detection value of the first pH value sensor is less than or equal to 7.5, the processing is stopped.

[0026] The beneficial effects of the present invention are as follows: a waste gas treatment system and a waste gas treatment method of the present invention, through the design of a waste gas treatment tower, a liquid alkali conveying device, a liquid alkali circulation pump, a first pH value sensor, a second pH value sensor, a third pH value sensor, a spray liquid discharge pipe and a program controller and the design of treatment process conditions, on the one hand, can ensure that the waste gas is harmlessly discharged after effective absorption, and on the other hand, can monitor and adjust the pH value of the spray liquid in the waste gas treatment tower and the pressure in the tower in real time and perform automatic feedback adjustment in time, which not only ensures the efficient absorption of waste gas and improves the waste gas treatment efficiency and treatment quality, but also can timely detect and regulate faults such as blockage, reduce maintenance difficulty and maintenance cost, and discharge the saturated solution obtained after spraying in time, recover by-products, and realize waste into treasure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the three-dimensional structure of a preferred embodiment of an exhaust gas treatment system of the present invention;

[0028] Figure 2 Schematic diagram of the cross-section structure of the spray liquid collecting device shown;

[0029] Figure 3 Schematic diagram of the structure of the spray liquid collector and the water collection tank from above;

[0030] Figure 4 1 is a schematic top view of the vertical pipe, the second horizontal pipe and the water distribution pipe in the water distributor;

[0031] Figure 5 This is a process flow diagram of a waste gas treatment method of the present invention;

[0032] The markings of the components in the accompanying drawings are as follows:

[0033] 100. Exhaust gas treatment tower, 110. Tower top exhaust port, 120. First tower section, 130. Second tower section, 140. Tower kettle, 150. Spray liquid collection device, 151. Spray liquid collector, 152. Water collection tank, 153. Water distributor, 1531. First transverse pipe, 1532. Vertical pipe, 1533. Second transverse pipe, 1534. Water distribution pipe; 160. Spray liquid discharge pipe, 161. Spray liquid discharge valve; 170. Steam inlet pipe, 171. Steam inlet valve; 180. Temperature sensor, 190. Pressure sensor;

[0034] 200. Liquid caustic soda conveying device, 210. First feeding valve, 220. Second feeding valve, 230. Liquid caustic soda conveying pump;

[0035] 300. Waste gas source storage tank; 400. Liquid alkali circulation pump;

[0036] 500. Vacuum pump, 510. Water-flushing vacuum pump, 520. Water-flushing pump head, 530. Three-way valve;

[0037] 600. First pH value sensor; 700. Second pH value sensor; 800. Third pH value sensor; 900. Cleaning water pipe, 910. Cleaning water valve. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0039] See also Figure 1-5 , embodiments of the present invention include:

[0040] Example 1

[0041] The present invention discloses a waste gas treatment system, comprising: a waste gas treatment tower 100, a liquid alkali conveying device 200, a waste gas source storage tank 300, a liquid alkali circulation pump 400, a vacuum device 500, a first pH sensor 600, a second pH sensor 700, a third pH sensor 800 and a program controller.

[0042] Specifically, the exhaust gas treatment tower 100 includes, from top to bottom, a tower top exhaust port 110, a first tower section 120, a second tower section 130 and a tower bottom 140. The first tower section 120 and the second tower section 130 are both installed with packing, and a spray liquid collection device 150 is installed below the packing. The spray liquid collection device 150 includes a spray liquid collector 151, a water collection tank 152 and a water distributor 153. Among them, the water collection tank 152 is an annular groove, which is installed on the inner wall of the exhaust gas treatment tower for temporarily storing spray liquid. The spray liquid collector 151 is a corrugated folding guide plate, which is placed horizontally on the water collection tank 152. The water outlets at both ends (i.e., the ends of the guide plate) are located above the notch of the water collection tank 152, and are used to guide the spray liquid after passing through the packing into the water collection tank 152. In addition, there are gaps between each guide plate for the passage of waste gas. The waste gas to be treated flows from bottom to top, passes through the above gaps, and comes into contact with the liquid alkali sprayed from top to bottom. The absorbable waste gas is absorbed by the liquid alkali and finally falls into the spray liquid collector 151 and then flows into the water collection tank 152.

[0043] The water distributor 153 includes a first transverse pipe 1531, a vertical pipe 1532, a second transverse pipe 1533, and a water distribution pipe 1534. The first transverse pipe 1531 is connected at both ends to the inner annular wall of the water collecting tank 152, the second transverse pipe 1533 is located below the first transverse pipe 1531, the vertical pipe 1532 is arranged vertically, and its two ends are connected to the first transverse pipe 1531 and the second transverse pipe 1533, respectively. The water distribution pipe 1534 is installed on both sides of the second transverse pipe 1533 by welding or threaded connection, and the pipe opening at the connecting end is connected to the second transverse pipe 1533. The water distribution pipe 1534 is also provided with a water distribution hole. The spray liquid collected in the water collecting tank 152 is immersed in the water distribution pipe 1534 through the first horizontal pipe 1531, the vertical pipe 1532 and the second horizontal pipe 1533 in turn, and finally dispersed through the water distribution holes and refluxed into the tower bottom 140. The design of the water distribution pipe can further increase the contact area between the spray liquid and the exhaust gas during the reflux process, thereby improving the exhaust gas absorption effect.

[0044] The first pH sensor 600 is connected to the spray liquid collecting device at the bottom of the first tower section 120 , specifically, to the sump 152 in the spray liquid collecting device, for real-time detection of the pH value of the spray liquid in the first tower section 120 .

[0045] The second pH sensor 700 is connected to the spray liquid collecting device at the bottom of the second tower section 130 and to the sump 152 in the spray liquid collecting device, and is used to detect the pH value of the spray liquid in the second tower section 130 in real time.

[0046] The third pH sensor 800 is connected to the tower bottom 140 and is used to detect the pH value of the liquid alkali in the tower bottom in real time.

[0047] The second tower section 130 is also connected to a spray liquid discharge pipe 160, which is connected to the sump 152 of the spray liquid collection device 150 on the corresponding tower section. A spray liquid discharge valve 161 is also installed on the spray liquid discharge pipe 160. The spray liquid discharge valve 161 is connected to the third pH value sensor 800 through a program controller for linkage control. When the third pH value sensor 800 detects that the pH value of the spray liquid is between 4.5 and 6, indicating that the liquid alkali has been absorbed to saturation, the program controller is used for linkage control to open the spray liquid discharge valve 161, and the spray liquid (i.e., saturated liquid) in the sump 152 is discharged and recovered. When the detected pH value is not between 4.5 and 6, the spray liquid discharge valve 161 is closed, and the spray liquid flows back to the tower kettle for continued recycling. The design of the spray liquid discharge pipe 160 allows the treated spray liquid to be promptly recovered to extract by-products, while preventing the spray liquid without waste gas treatment function from flowing back to the bottom of the tower and affecting the pH value of the bottom liquid.

[0048] In addition, the tower bottom 140 is located above the liquid alkali liquid level and is also equipped with a steam inlet pipe 170. The steam inlet pipe 170 is provided with a steam inlet valve 171 for transporting hot steam into the waste gas treatment tower to adjust the temperature inside the waste gas treatment tower so that the temperature inside the tower top reaches 40-60°C. Specifically, a temperature sensor 180 for detecting the temperature is also installed in the exhaust port at the top of the tower. The steam inlet valve 171 and the temperature sensor 180 are connected through the linkage control of the program controller.

[0049] The waste gas source storage tank 300 is connected to the tower bottom 140 through an air intake pipe with a gas flow meter (not shown). The vacuum pumping device 500 is connected to the tower bottom 140. Specifically, the vacuum pumping device 500 includes a water-flushing vacuum pump 510, a water-flushing pump head 520 and a three-way valve 530. The three-way valve is connected to the air intake pipe, the water-flushing vacuum pump 510 and the water-flushing pump head 520, respectively. Through the design of the vacuum pumping device 500 and its connection with the air intake pipe, the waste gas generated by the waste gas source storage tank 300 is sprayed into the waste gas treatment tower 100 under the condition of -0.001 to -0.01 MPa, ensuring that the waste gas is completely absorbed under negative pressure.

[0050] The liquid caustic soda conveying device 200 is connected to the first tower section 120 via a pipeline with a first feed valve 210. The end of the pipeline is located above the packing of the first tower section 120 and is connected to a nozzle for spraying liquid caustic soda into the first tower section to increase the contact area with the exhaust gas. The liquid caustic soda conveying device 200 is connected to the tower bottom 140 via a pipeline with a second feed valve 220 for conveying liquid caustic soda into the tower bottom. Specifically, the first pH sensor 600 is connected to the first feed valve 210 through a program controller, and the third pH sensor 800 is connected to the second feed valve 220 through a program controller. Under normal operating conditions, the pH value measured in real time by the first pH sensor 600 is required to be greater than 9, and the pH value measured in real time by the third pH sensor 800 is required to be greater than or equal to 7.5 and less than or equal to 8.0. Therefore, the first pH sensor 600 and the third pH sensor 800 regulate the opening of the first feed valve 210 to 10-30% and the opening of the second feed valve 220 to 70-90%, ensuring that 20% of the liquid caustic soda conveying device 200 is sprayed into the first tower section 120 and 80% is conveyed into the tower kettle 140. Controlling the pH value of the spray liquid in the first tower section 120 ensures that the waste gas about to leave the waste gas treatment tower 100 can be further effectively absorbed and treated, ensuring that the discharged gas is effectively purified and pollution-free.

[0051] Specifically, the liquid caustic soda conveying device 200 includes a liquid caustic soda conveying pump 230 , which is an existing pressure-transmitting pump and can select the liquid caustic soda conveying amount according to the amount of waste gas generated.

[0052] The liquid caustic soda circulation pump 400 is located outside the waste gas treatment tower 100. Its liquid inlet is connected to the tower kettle 140 via a pipe, and its liquid outlet is connected to the second tower section 130 via a pipe. The end of the pipe connected to the liquid outlet is equipped with a nozzle and extends above the packing in the second tower section 130. It is used to spray the liquid caustic soda in the tower kettle 140 into the second tower section to increase the contact area with the waste gas. The design of the liquid caustic soda circulation pump 400 enables the liquid caustic soda in the tower kettle to be rotated and sprayed within the waste gas treatment tower 100, thereby increasing the contact area between the liquid caustic soda and the waste gas and improving the waste gas treatment effect.

[0053] The tower kettle 140 is also equipped with a pressure sensor 190, which is connected to the program controller. The first tower section 120 is also connected to a wash water pipe 900, which is equipped with a wash water valve 910. The wash water valve 910 and the pressure sensor 190 are linked and controlled by the program controller. The wash water pipe 900 is used to supply wash water to the exhaust gas treatment tower 100, resolving blockage issues within the exhaust gas treatment tower 100. Under normal circumstances, the pressure within the exhaust gas treatment tower 100 is between 0 and 0.1 MPa. When the pressure sensor 190 detects a pressure higher than 0.1 MPa, it indicates a blockage within the tower. At this point, the wash water valve 910 can be activated to supply wash water to the exhaust gas treatment tower 100 until the pressure sensor 190 detects a pressure of 0.1 MPa or less.

[0054] Example 2

[0055] The method for treating sulfur dioxide (SO2) waste gas using the above waste gas treatment system specifically comprises the following steps:

[0056] (1) Waste gas absorption: The SO2 waste gas in the waste gas source storage tank 300 is injected into the waste gas treatment tower 100 through the water pump head 520 at a pressure of -0.001 to -0.01 MPa through the vacuum device, and the injection amount of SO2 is metered by the gas flow meter;

[0057] (2) Liquid caustic soda feed: The liquid caustic soda is a sodium hydroxide solution with a mass concentration of 25%. According to the principle of SO2+2NaOH→Na2SO3+H2O, the amount of liquid caustic soda required for treating SO2 in step (1) is calculated, and then the liquid caustic soda is delivered to the waste gas treatment tower 100 through the liquid caustic soda delivery pump. Specifically, by adjusting the openings of the first feed valve 210 and the second feed valve 220, 20% of the total amount of liquid caustic soda delivered is sprayed into the first tower section 120 through the first feed valve 210, and the remaining 80% is delivered to the tower bottom 140 through the second feed valve 220, so as to ensure that the pH value detected by the first pH sensor is greater than 9 and the pH value detected by the third pH sensor is between 7.5 and 8;

[0058] (3) Waste gas treatment: The liquid alkali in the tower kettle 140 is circulated and sprayed into the second tower section 130 through the liquid alkali circulation pump 400 to react with the waste gas, and the spray liquid after the reaction enters the spray liquid collecting device 150 at the bottom of the tower section; when the pH value detected by the second pH value sensor 700 is between 4.5 and 6, the spray liquid discharge valve 161 is opened by the program controller to discharge the spray liquid from the spray liquid discharge pipe 160, and the by-product Na2SO3 is recovered and processed, thereby realizing waste recycling; when the second pH value sensor 700 detects that the pH value of the spray liquid in the spray liquid collecting device is not between 4.5 and 6, the spray liquid discharge valve 161 remains closed, and the spray liquid flows back to the tower kettle to continue circulating and spraying; after the SO2 waste gas flowing from bottom to top in the waste gas treatment tower 100 is absorbed by the liquid alkali in each tower section, the remaining harmless tail gas is discharged and released from the exhaust port 110 at the top of the tower, thereby realizing harmless treatment of the SO2 waste gas.

[0059] During the above-mentioned waste gas absorption treatment process, hot steam is introduced into the waste gas treatment tower 100 through the steam inlet pipe 170, and the opening of the steam inlet valve 171 is adjusted by the program controller, so that the temperature sensor 180 detects the temperature of the top of the tower to ensure that the temperature is between 40 and 60°C. By controlling the temperature in the tower, the crystals produced during the reaction process can be cleared to a certain extent to prevent the waste gas treatment tower from being blocked.

[0060] Example 3

[0061] The method for treating nitrogen dioxide (NO2) waste gas using the above waste gas treatment system specifically includes the following steps:

[0062] (1) Waste gas absorption: The NO2 waste gas in the waste gas source storage tank 300 is injected into the waste gas treatment tower 100 through the water pump head 520 at a pressure of -0.001 to -0.01 MPa through the vacuum device, and the injection amount of NO2 is measured by the gas flow meter;

[0063] (2) Liquid caustic soda feed: The liquid caustic soda is a sodium hydroxide solution with a mass concentration of 30%. According to the principle of 2NO2+2NaOH=NaNO3+NaNO2+H2O, the amount of liquid caustic soda required for treating NO2 in step (1) is calculated, and then the liquid caustic soda is delivered to the waste gas treatment tower 100 through the liquid caustic soda delivery pump. Specifically, by adjusting the openings of the first feed valve 210 and the second feed valve 220, 20% of the total amount of liquid caustic soda delivered is sprayed into the first tower section 120 through the first feed valve 210, and the remaining 80% is delivered to the tower bottom 140 through the second feed valve 220, so as to ensure that the pH value detected by the first pH sensor is greater than 9 and the pH value detected by the third pH sensor is between 7.5 and 8;

[0064] (3) Waste gas treatment: The liquid alkali in the tower bottom 140 is circulated and sprayed into the second tower section 130 through the liquid alkali circulation pump 400 to react with the waste gas, and the spray liquid after the reaction enters the spray liquid collecting device 150 at the bottom of the tower section; when the pH value detected by the second pH value sensor 700 is between 4.5 and 6, the spray liquid discharge valve 161 is opened by the program controller to discharge the spray liquid from the spray liquid discharge pipe 160, and the by-products NaNO3 and NaNO2 are recovered and processed, thereby realizing waste recycling; when the second pH value sensor 700 detects that the pH value of the spray liquid in the spray liquid collecting device is not between 4.5 and 6, the spray liquid discharge valve 161 remains closed, and the spray liquid flows back to the tower bottom to continue circulating and spraying; after the NO2 waste gas flowing from bottom to top in the waste gas treatment tower 100 is absorbed by the liquid alkali in each tower section, the remaining harmless tail gas is discharged and released from the exhaust port 110 at the top of the tower, thereby realizing harmless treatment of the NO2 waste gas.

[0065] The temperature control process and method in the tower are the same as in Example 2.

[0066] Example 4

[0067] Troubleshooting

[0068] During the above-mentioned waste gas treatment process, the pressure value in the tower is detected in real time by the pressure sensor 190. When the pressure value is greater than 0.1 MPa, it indicates that there is blockage in the tower. The cleaning water valve 910 is then opened through the program controller to spray cleaning water from the first tower section 120 into the tower to clear the blockage. When the pressure sensor 190 detects that the pressure value in the tower has returned to below 0.1 MPa, the cleaning water valve 910 is closed.

[0069] In addition, if the pH value detected by the first pH sensor 600 is less than or equal to 7.5, it indicates that there is a serious fault in the exhaust gas treatment tower, and the production must be stopped immediately.

[0070] The design of the exhaust gas treatment system according to the present invention is used to perform fault processing, thereby achieving real-time and automated fault detection and elimination, and achieving high efficiency in fault detection and treatment.

[0071] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An exhaust gas treatment system, characterized in that: include: An exhaust gas treatment tower, comprising, from top to bottom, a tower top exhaust port, two or more tower sections, and a tower kettle; a spray liquid collection device is installed at the bottom of each tower section; the spray liquid collection device located at the topmost tower section is connected to a first pH value sensor, the spray liquid collection device located at the bottommost tower section is connected to a second pH value sensor and a spray liquid discharge pipe, and the tower kettle is connected to a third pH value sensor; a liquid caustic soda conveying device, the liquid caustic soda conveying device being connected to the topmost tower section of the exhaust gas treatment tower through a pipeline with a first feeding valve, and being connected to the tower kettle through a pipeline with a second feeding valve; A waste gas source storage tank, the waste gas source storage tank is connected to the tower kettle through an air inlet pipe; a liquid caustic soda circulation pump, wherein the liquid inlet of the liquid caustic soda circulation pump is connected to the tower kettle through a pipeline, and the liquid outlet of the liquid caustic soda circulation pump is connected to the second tower section from top to bottom through a pipeline; A vacuum pumping device, the vacuum pumping device being connected to the tower bottom; A program controller, wherein the first pH sensor and the first feeding valve are connected through linkage control of the program controller; the second pH sensor and the spray liquid discharge valve on the spray liquid discharge pipe are connected through linkage control of the program controller; and the third pH sensor and the second feeding valve are connected through linkage control of the program controller.

2. The exhaust gas treatment system according to claim 1, characterized in that: The opening ratio of the first feeding valve to the second feeding valve is 10% to 30%: 70% to 90%.

3. The exhaust gas treatment system according to claim 2, characterized in that: The tower section is provided with packing, and the spray liquid collecting device is located below the packing; the spray liquid collecting device includes a spray liquid collector, a water collecting trough and a water distributor; wherein, the spray liquid collector is a corrugated folding guide plate, which is horizontally placed above the water collecting trough, and the two ends of the guide plate are located above the notch of the water collecting trough; the water collecting trough is an annular groove installed on the inner wall surface of the exhaust gas treatment tower; the water distributor includes a first transverse pipe, a vertical pipe, a second transverse pipe and a water distribution pipe, wherein the two ends of the first transverse pipe are connected to the inner ring wall of the water collecting trough, the second transverse pipe is located below the first transverse pipe, the two ends of the vertical pipe are connected to the first transverse pipe and the second transverse pipe respectively, the water distribution pipe is installed on both sides of the second transverse pipe and connected to the second transverse pipe, and a water distribution hole is provided on the water distribution pipe; the spray liquid discharge pipe is connected to the water collecting trough.

4. The exhaust gas treatment system according to claim 1, characterized in that: The vacuum pumping device includes a water-flushing vacuum pump, a water-flushing pump head and a three-way valve. One end of the water-flushing vacuum pump is connected to the tower kettle, and the other end is connected to the three-way valve. The three-way valve is also connected to the air inlet pipe and the water-flushing pump head. The water outlet end of the water-flushing pump head extends into the tower kettle.

5. The exhaust gas treatment system according to claim 3, characterized in that: The tower kettle is also equipped with a pressure sensor, which is connected to the program controller.

6. The exhaust gas treatment system according to claim 5, characterized in that: The tower kettle is also connected to a steam inlet pipe, which is provided with a steam inlet valve. A temperature sensor is also installed in the tower top exhaust port. The steam inlet valve and the temperature sensor are connected through linkage control of the program controller.

7. The exhaust gas treatment system according to claim 6, characterized in that: The topmost tower section is also connected to a cleaning water pipe, the cleaning water pipe is provided with a cleaning water valve, and the cleaning water pipe and the pressure sensor are connected through linkage control of the program controller.

8. A method for treating waste gas using the waste gas treatment system according to claim 7, characterized in that: The steps include: (1) Waste gas absorption: The waste gas in the waste gas source storage tank is ejected into the waste gas treatment tower under negative pressure through the vacuum pumping device; (2) Liquid caustic soda feeding: determining the delivery amount of liquid caustic soda according to the type and amount of the waste gas, and then delivering the required amount of liquid caustic soda to the waste gas treatment tower through the first feeding valve and the second feeding valve respectively, and regulating the opening of the first feeding valve and the second feeding valve according to the detection value of the first pH value sensor and the detection value of the third pH value sensor; (3) Waste gas treatment: the liquid alkali in the tower kettle is circulated and sprayed into the second tower section through the liquid alkali circulation pump to react with the waste gas, and the spray liquid after the reaction enters the spray liquid collecting device at the bottom of the tower section; when the second pH value sensor detects that the pH value of the spray liquid in the spray liquid collecting device is between 4.5 and 6, the spray liquid discharge valve is opened by the program controller to recover the spray liquid; when the second pH value sensor detects that the pH value of the spray liquid in the spray liquid collecting device is not between 4.5 and 6, the spray liquid discharge valve is in a closed state, and the spray liquid in the spray liquid collecting device is returned to the tower kettle to continue circulating and spraying, and the treated gas is discharged from the exhaust port at the top of the tower.

9. The method for treating waste gas according to claim 8, characterized in that: In step (2), when the detection value of the first pH sensor is greater than 9, the opening of the first feeding valve is 10% to 30%; when the detection value of the third pH sensor is 7.5 to 8, the opening of the second feeding valve is 70% to 90%.

10. The waste gas treatment method according to claim 9, characterized in that: It also includes a fault detection and processing step, and the fault detection and processing method is: when the program controller detects that the pressure value of the pressure sensor is greater than 0.1MPa, the cleaning water valve is opened to input cleaning water into the exhaust gas treatment tower until the pressure value of the pressure sensor recovers to 0~0.1MPa; when the detection value of the first pH value sensor is less than or equal to 7.5, the processing is stopped.

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