Comprehensive treatment system for tail gas of steel mill

Abstract

The invention relates to a comprehensive treatment system for tail gas of a steel mill. The system comprises a pre-treatment module, an absorption tower, a liquid circulator, crystal quantity detectors and a liquid supplementing module, wherein the pre-treatment module is used for carrying out dust removal, desulfurization and denitration treatment on tail gas; the absorption tower is connected with the output end of the pre-treatment module; the liquid circulator is connected with the absorption tower and forms a loop; gas in the absorption tower flows from bottom to top, liquid in the absorption tower flows from top to bottom, the crystal amount detector is used for detecting the crystal generation amount, and the liquid circulator is used for adjusting the flowing speed of the liquid in the absorption tower according to the detection result of the crystal amount detector. According to the comprehensive treatment system for the tail gas of the steel mill, the amount of crystals generated in the treatment process can be actively measured, the flowing speed of an absorbent can be matched with the input speed of the tail gas in the mode, and energy consumption can be reduced while a good absorption effect is obtained.

Description

Technical Field

[0001] The present application relates to the field of industrial environmental protection technology, and in particular to a comprehensive treatment system for steel plant tail gas. Background Art

[0002] The comprehensive treatment of steel mill exhaust gas includes clean energy substitution, low-pollution production processes, end-of-pipe treatment technologies (dust removal, desulfurization, and denitrification), coordinated treatment of multiple pollutants (adsorption and catalytic oxidation), waste heat power generation and recovery, etc. A major purpose of these treatment methods is to reduce the impact on the surrounding environment and achieve full utilization of materials.

[0003] With the development of technology and the further improvement of environmental protection requirements, requirements for carbon oxides in exhaust gas have begun to be put forward, because the concentrated emission of large amounts of carbon oxides will damage the ecosystem and biodiversity to a certain extent, and will also cause acid corrosion, etc.

[0004] At present, the treatment of carbon oxides in exhaust gas is based on a phase change reaction. The advantages of this treatment method are low energy consumption, low absorbent loss and no indirect products. The specific treatment process is to input the treated exhaust gas into the absorbent for treatment. The absorbent reacts with the carbon oxides to form crystals, and the crystals are pyrolyzed at high temperature to obtain the absorbent again.

[0005] An important factor affecting the above process is controlling the growth rate of the crystals. If the crystals are too large or too small, it means that the flow rate of the absorbent is not matched, and there is also the problem of high energy consumption. Summary of the Invention

[0006] The present application provides a comprehensive treatment system for steel plant exhaust gas, which can actively measure the amount of crystals produced during the treatment process. This method can match the flow rate of the absorbent with the input rate of the exhaust gas, thereby achieving better absorption effect while also helping to reduce energy consumption.

[0007] The above-mentioned purpose of this application is achieved through the following technical solutions: This application provides a comprehensive treatment system for steel mill tail gas, including: Pre-treatment module, used for dust removal, desulfurization and denitrification of exhaust gas; The absorption tower is connected to the output end of the pre-processing module, and the gas in the absorption tower flows from bottom to top; The liquid circulator is connected to the absorption tower to form a loop, and the liquid in the absorption tower flows from top to bottom; A crystal quantity detector is arranged at intervals on the absorption tower and is used to detect the amount of crystal generated; Liquid replenishment module, connected to the absorption tower or liquid circulator; The liquid circulator is used to adjust the liquid flow rate in the absorption tower according to the detection results of the crystal amount detector.

[0008] In a possible implementation of the present application, the liquid circulator includes: A water distributor is provided in the absorption tower and is located below the liquid level in the absorption tower; Liquid return pipe, connected to the absorption tower; The circulation pump is connected to the return liquid pipeline and the circulation pump.

[0009] In a possible implementation of the present application, an interception cover is provided on the inner wall of the absorption tower, and the connection between the liquid return pipe and the absorption tower is located between the interception cover and the inner wall of the absorption tower; The space formed by the interception cover and the inner wall of the absorption tower faces the bottom of the absorption tower.

[0010] In a possible implementation of the present application, the water distributor has multiple output ends, and the multiple output ends are evenly arranged on a plane perpendicular to the axis of the absorption tower; A flow valve is provided on the output end; A plurality of flow velocity sensors are arranged in the absorption tower, and the plurality of flow velocity sensors are evenly arranged on a plane perpendicular to the axis of the absorption tower.

[0011] In a possible implementation of the present application, the crystal quantity detector includes: The sampler is located inside the absorption tower; The sampling pipeline is connected with the sampler and the absorption tower to form a loop; A first electronically controlled sampling pump is provided on the sampling pipeline; A diversion pipe is connected to the sampling pipe and the absorption tower to form a loop, and a switching valve is provided at the connection between the diversion pipe and the sampling pipe; The metering box is installed on the diversion pipeline; an interception filter is installed in the metering box; The second electronically controlled sampling pump is arranged on the diversion pipeline and is located behind the metering box.

[0012] In a possible implementation of the present application, a laser ranging sensor and a float are provided inside the metering box.

[0013] In a possible implementation of the present application, the following is further included: The electric heating wire is arranged on the outer wall of the meter box or inside the meter box; Purge pipeline, connected to metering box.

[0014] In a possible implementation of the present application, a regeneration module connected to the absorption tower is further included, and the regeneration module is used to thermally decompose the crystals generated in the absorption tower.

[0015] In one possible implementation of the present application, the regeneration module includes: A pyrolysis tower connected to an absorption tower; Two sets of pyrolysis plates are symmetrically and alternately arranged inside the pyrolysis tower; Among them, the end of the pyrolysis plate away from the inner wall of the pyrolysis tower is inclined toward the bottom of the pyrolysis tower.

[0016] In a possible implementation of the present application, there is a gap between one end of the pyrolysis plate close to the inner wall of the pyrolysis tower and the inner wall of the pyrolysis tower.

[0017] The beneficial effects of this application are: The comprehensive treatment system for steel plant exhaust gas disclosed in this application determines whether the flow rates of the absorbent and the exhaust gas are appropriate by actively measuring the generated crystals at multiple locations. When the flow rates of the two do not match, timely adjustments can be made to match the speeds of the two to ensure that the particle size of the crystals obtained meets the requirements of subsequent regeneration treatment, thereby achieving optimized control of the circulation energy consumption and regeneration energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural schematic diagram of a comprehensive treatment system for steel plant tail gas provided in this application.

[0019] Figure 2 This is a schematic diagram of the internal structure of an absorption tower provided in this application.

[0020] Figure 3 This is a distribution diagram of the output end of a water distributor provided in this application.

[0021] Figure 4 This is a deployment diagram of a flow rate sensor provided in this application.

[0022] Figure 5 This is a structural schematic diagram of a crystal quantity detector provided in this application.

[0023] Figure 6 This is a schematic diagram of the absorbent flow path corresponding to the crystal quantity detector during detection provided by this application.

[0024] Figure 7 This is a schematic diagram of the internal structure of a metering box provided in this application.

[0025] Figure 8 This is a structural diagram of a regeneration module provided in this application.

[0026] In the figure, 1. pre-processing module, 2. absorption tower, 3. liquid circulator, 4. crystal quantity detector, 5. liquid replenishing module, 6. regeneration module, 21. flow rate sensor, 31. water distributor, 32. return liquid pipeline, 33. circulation pump, 34. interception cover, 41. sampler, 42. sampling pipeline, 43. first electric-controlled sampling pump, 44. diversion pipeline, 441. switching valve, 45. metering box, 46. interception filter, 47. second electric-controlled sampling pump, 451. laser ranging sensor, 452. float, 453. electric heating wire, 454. purge pipeline, 61. pyrolysis tower, 62. pyrolysis plate, 311. output end, 312. flow valve. DETAILED DESCRIPTION

[0027] The technical solution in this application is further described in detail below with reference to the accompanying drawings.

[0028] The present application discloses a comprehensive treatment system for steel plant exhaust gas. In some examples, the comprehensive treatment system for steel plant exhaust gas disclosed in the present application includes a pre-treatment module 1, an absorption tower 2, a liquid circulator 3, a crystal quantity detector 4 and a liquid replenishment module 5.

[0029] See also Figure 1 The function of the pre-treatment module 1 is to remove dust, desulfurize and denitrify the exhaust gas. The pre-treatment module 1 has an input end and an output end. The input end of the pre-treatment module 1 is connected to the exhaust gas pipeline. It specifically includes a dust collector (lower left), a desulfurization tower (upper right), a denitrification tower (upper right) and a heat exchanger. The dust collector generally chooses a dry dust removal method in which a cyclone dust collector and a bag dust collector are connected in series. If the steel plant has sufficient electricity, an electrostatic dust collector can be selected.

[0030] After dust removal, desulfurization, and denitrification, the exhaust gas is sent to absorption tower 2 for recovery of nitrogen oxides (primarily CO2). Absorption tower 2 is connected to the output end of pre-processing module 1. After the exhaust gas from pre-processing module 1 enters absorption tower 2, its flow direction is from bottom to top.

[0031] The liquid circulator 3 is connected to the absorption tower 2 to form a loop, driving the liquid (absorbent, hereinafter referred to as absorbent) in the absorption tower 2 to flow from top to bottom. That is, inside the absorption tower 2, the flow directions of the liquid and the gas are opposite. The purpose is to increase the contact time between the gas and the liquid. The crystals generated during the contact process fall to the bottom of the absorption tower 2 under the action of gravity and are then transferred to the regeneration process for treatment.

[0032] In some possible implementations, the liquid circulator 3 includes a circulation pump and a pipeline.

[0033] After crystal regeneration (pyrolysis), absorbent and high-concentration CO2 gas are produced. This CO2 gas can be temporarily stored by compression and then used as a production raw material or stored for processing. The absorbent produced after crystal regeneration (pyrolysis) is returned to the absorption tower 2 for recycling.

[0034] Crystal quantity detectors 4 are spaced apart on absorption tower 2 to monitor the crystal growth process. Specifically, multiple crystal quantity detectors 4 are located at different locations (heights) on absorption tower 2 to monitor the entire crystal growth process. Specifically, at each height, the crystal quantity generated should meet the requirements for that location.

[0035] The liquid replenishment module 5 is connected to the absorption tower 2 or the liquid circulator 3, and its function is to replenish the absorbent in the absorption tower 2. This is because the absorbent is lost during the treatment process described in the above content. In this application, the liquid level in the absorption tower 2 is required to remain unchanged.

[0036] In some possible implementations, a liquid level sensor is installed near the top of the absorption tower 2, and the liquid replenishment module 5 adjusts the liquid level in the absorption tower 2 according to a feedback signal from the liquid level sensor.

[0037] In some possible implementations, the liquid replenishment module 5 includes a storage tank and a replenishment pump. The number of replenishment pumps is two or has a direction adjustment function, that is, it can not only replenish the absorbent into the absorption tower 2, but also transfer the absorbent from the absorption tower 2 to the storage tank.

[0038] The liquid circulator 3 is used to adjust the liquid flow rate in the absorption tower 2 according to the detection results of the crystal amount detector 4. The specific analysis is as follows: When insufficient crystal formation is detected, the reasons include a decrease in the nitrogen oxide content in the exhaust gas and an excessively fast flow rate of the absorbent; when excessive crystal formation is detected, the reasons include an increase in the nitrogen oxide content in the exhaust gas and an excessively slow flow rate of the absorbent.

[0039] At this time, it is necessary to first detect the nitrogen oxide content in the exhaust gas. If the nitrogen oxide content in the exhaust gas is high, it can be diluted and then sent to the absorption tower 2 for treatment, or the liquid flow rate in the absorption tower 2 can be adjusted.

[0040] The purpose of this treatment method is to avoid secondary treatment of the tail gas as much as possible, that is, sending it into the absorption tower 2 for treatment again, because this will increase unnecessary energy consumption.

[0041] When the crystal output is insufficient, it means that there will be a certain amount of heat waste in the subsequent regeneration process. Otherwise, the crystal will not be completely pyrolyzed, and a secondary regeneration will be required, which will increase additional heat consumption.

[0042] For some examples, see Figure 2 The liquid circulator 3 includes a water distributor 31, a return liquid pipe 32 and a circulation pump 33. The water distributor 31 is installed in the absorption tower 2 and is located below the liquid level in the absorption tower 2. The return liquid pipe 32 is connected to the absorption tower 2, and the circulation pump 33 is connected to the return liquid pipe 32 and the circulation pump 33.

[0043] When the circulation pump 33 is working, it drives the absorbent to circulate between the absorption tower 2 and the liquid return pipe 32. Another function of the circulation pump 33 is to adjust the flow rate of the absorbent in the absorption tower 2.

[0044] For some examples, see Figure 2 An interception cover 34 is added to the inner wall of the absorption tower 2, and the connection between the return liquid pipe 32 and the absorption tower 2 is located between the interception cover 34 and the inner wall of the absorption tower 2. The space formed by the interception cover 34 and the inner wall of the absorption tower 2 faces the bottom of the absorption tower 2.

[0045] The function of the interception cover 34 is to prevent the generated crystals from flowing into the return liquid pipe 32. On the one hand, it is to avoid additional mechanical wear on the return liquid pipe 32 and the circulation pump 33. On the other hand, it is to avoid additional flow distance of the crystals, because such flow may cause the crystals to break and fail to settle to the bottom of the absorption tower 2.

[0046] For some examples, see Figure 2 and Figure 3 The water distributor 31 has multiple output ends 311 , which are evenly arranged on a plane perpendicular to the axis of the absorption tower 2 , and a flow valve 312 is added to each output end 311 .

[0047] In some possible implementations, the water distributor 31 is a ring-shaped pipe, and the output ends 311 are evenly distributed on the ring-shaped pipe. The purpose of adding the output end 311 and adding a flow valve 312 to each output end 311 is to control the flow rate of the absorbent at various locations within the absorption tower 2 to be uniform. This method can make the contact time between the absorbent and the tail gas at various locations within the absorption tower 2 uniform, and at the same time help to obtain a uniform crystal particle size.

[0048] The advantage of the particle size tending to be consistent is that in the later pyrolysis regeneration process, the pyrolysis consumption time of the crystals tends to be stable, which can effectively shorten the invalid time increased to ensure the pyrolysis effect.

[0049] The flow valve 312 is controlled by a flow rate sensor 21. There are multiple flow rate sensors 21, which are evenly arranged on a plane perpendicular to the axis of the absorption tower 2. Each flow rate sensor 21 is responsible for the flow rate measurement of an area, and corresponds to a single flow valve 312 or multiple flow valves 312 in a given area.

[0050] See also Figure 4 The flow rate sensor 21 is deployed in a manner that uses a ring bracket as a support, and the flow rate sensor 21 is directly fixedly mounted on the ring bracket.

[0051] For some examples, see Figure 5 The crystal quantity detector 4 includes a sampler 41, a sampling pipe 42, a first electrically controlled sampling pump 43, a diversion pipe 44, a switching valve 441, a metering box 45, an intercepting filter 46 and a second electrically controlled sampling pump 47. The sampler 41 is installed inside the absorption tower 2 and its function is to perform sampling. The sampling pipe 42 is connected to the sampler 41 and the absorption tower 2 to form a loop, and its function is to perform fixed-point sampling and quantitative sampling.

[0052] Specifically, the sampler 41 is arranged horizontally inside the absorption tower 2 and has multiple input ports. Each input port corresponds to a different position. Only one input port is opened for each sampling, so that fixed-point sampling can be performed. At this time, the sample obtained flows in the sampler 41 and the sampling pipe 42. Figure 5 As shown by the arrow in FIG, when the set time is reached, the switching valve 441 on the diversion pipe 44 is opened, allowing the sample to flow into the diversion pipe 44, as shown in FIG. Figure 6 As shown by the arrow in .

[0053] The purpose of allowing the sample to flow in the sampler 41 and the sampling pipe 42 for a certain period of time is to remove the residue from the previous sampling process. The first electronically controlled sampling pump 43 is installed on the sampling pipe 42 and is responsible for driving the sample to flow in the sampler 41 and the sampling pipe 42.

[0054] The diversion pipe 44 is connected to the sampling pipe 42 and the absorption tower 2 to form a loop. At the same time, a metering box 45 is also set on the diversion pipe 44. The purpose of the metering box 45 is to perform volume detection on the sample obtained by quantitative sampling. The quantitative sampling here is achieved by switching the fixed opening time of the valve 441.

[0055] An interception filter 46 is installed in the metering box 45 to intercept crystals of a specified size. A second electronically controlled sampling pump 47 is installed on the diversion pipe 44 and is located behind the metering box 45. When the sample flows into the metering box 45, the second electronically controlled sampling pump 47 is in the off state. After the test is completed, the second electronically controlled sampling pump 47 is turned on and the sample in the metering box 45 is returned to the absorption tower 2.

[0056] For quantitative collection of samples, the volume is V1. After being intercepted by the interception filter 46, the volume becomes V2. At this time, the volume difference V=V1-V2. The volume difference V corresponds to the amount of crystals generated at different height positions. By comparing with the standard value, it can be determined whether the crystal generation amount at the current position meets the requirements.

[0057] That is, at different height positions, the values ​​of the volume difference V are different, and the corresponding apertures of the intercepting filter 46 are also different.

[0058] See also Figure 7 A laser distance sensor 451 and a float 452 are provided inside the metering box 45. The function of the laser distance sensor 451 is to perform height detection. The value obtained at this time is H, the bottom area of ​​the metering box 45 is S, and the volume of the sample V=HxS.

[0059] The float 452 can use a hollow ball, which is connected to the slide rail and can slide on the slide rail. The laser ranging sensor 451 is located above the float 452 and directly detects the upper surface of the hollow ball. Height correction needs to be introduced here, that is, the data obtained by detection needs to be added with a constant to obtain the height above the liquid surface.

[0060] The function of the float 452 is to cooperate with the laser ranging sensor 451 to perform height detection, because the laser needs to be reflected on the surface of the float 452.

[0061] At the same time, an electric heating wire 453 and a purge pipe 454 are added. The electric heating wire 453 is located on the outer wall of the metering box 452 or inside the metering box 452. Here, the inside refers to the presence of an interlayer in the metering box 452, and the electric heating wire 453 is located inside the interlayer.

[0062] The function of the electric heating wire 453 is to heat so that the crystals remaining inside the metering box 45 can be pyrolyzed, and the function of the purge pipe 454 is to dry the inside of the metering box 45. The functions of the two are to ensure that there will be no residue on the inner wall of the metering box 45 every time it works.

[0063] At this time, it is also necessary to add an exhaust valve or exhaust hole to the metering box 45 for exhaust.

[0064] The electric heating wire 453 is powered by an external power supply, and the air source used by the purge pipe 454 can be provided by an air pump on the ground, or by a micro air pump installed on the outer wall of the metering box 45.

[0065] For some examples, see Figure 1 and Figure 8A regeneration module 6 connected to the absorption tower 2 is also added. The regeneration module 6 is used to thermally decompose the crystals produced in the absorption tower 2. It is specifically composed of a pyrolysis tower 61 and a pyrolysis plate 62. There are two groups of pyrolysis plates 62, and the two groups of pyrolysis plates 62 are symmetrically and alternately arranged inside the pyrolysis tower 61.

[0066] The crystals produced in absorption tower 2 are transported to pyrolysis tower 61, where they move downward. The heat source for pyrolysis plates 62, typically steel mill waste heat, is piped into the plates. The crystals are pyrolyzed while in contact with the plates 62. The crystals are also broken down by falling. This combination of factors allows for rapid pyrolysis of the crystals as they fall.

[0067] In some possible implementations, one end of the pyrolysis plate 62 away from the inner wall of the pyrolysis tower 61 is tilted toward the bottom of the pyrolysis tower 61 , in order to speed up the movement of the crystals.

[0068] In some possible implementations, a gap exists between the end of pyrolysis plate 62 near the inner wall of pyrolysis tower 61 and the inner wall of pyrolysis tower 61. This gap allows for the flow of pyrolysis gas. This prevents the movement path of the crystals from interfering with the path of the pyrolysis gas, thus preventing the crystals from being disturbed by the airflow and causing their movement speed to decrease or even become suspended.

[0069] The valves and sensors described above are all connected to a unified control cabinet for control. The core of the control cabinet is implemented using a programmable logic controller in combination with peripheral circuits. This part of the content is existing technology and will not be repeated here.

[0070] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A comprehensive treatment system for steel plant tail gas, characterized in that: include: A pre-treatment module (1) for removing dust, desulfurizing and denitrifying the exhaust gas; The absorption tower (2) is connected to the output end of the pre-processing module (1), and the gas in the absorption tower (2) flows from bottom to top; The liquid circulator (3) is connected to the absorption tower (2) to form a loop, and the liquid in the absorption tower (2) flows from top to bottom; A crystal quantity detector (4) is arranged at intervals on the absorption tower (2), and the crystal quantity detector (4) is used to detect the amount of crystal generated; A liquid replenishing module (5) is connected to the absorption tower (2) or the liquid circulator (3); The liquid circulator (3) is used to adjust the liquid flow rate in the absorption tower (2) according to the detection result of the crystal amount detector (4).

2. The comprehensive treatment system for steel mill tail gas according to claim 1, characterized in that: The liquid circulator (3) comprises: A water distributor (31) is provided in the absorption tower (2) and is located below the liquid level in the absorption tower (2); A liquid return pipe (32) connected to the absorption tower (2); The circulation pump (33) is connected to the liquid return pipe (32) and the circulation pump (33).

3. The comprehensive treatment system for steel mill tail gas according to claim 2, characterized in that: An interception cover (34) is provided on the inner wall of the absorption tower (2), and the connection between the liquid return pipe (32) and the absorption tower (2) is located between the interception cover (34) and the inner wall of the absorption tower (2); The space formed by the interception cover (34) and the inner wall of the absorption tower (2) faces the bottom of the absorption tower (2).

4. The comprehensive treatment system for steel mill tail gas according to claim 2, characterized in that: The water distributor (31) has a plurality of output ends (311), and the plurality of output ends (311) are evenly arranged on a plane perpendicular to the axis of the absorption tower (2); A flow valve (312) is provided on the output end (311); A plurality of flow rate sensors (21) are provided in the absorption tower (2), and the plurality of flow rate sensors (21) are evenly arranged on a plane perpendicular to the axis of the absorption tower (2).

5. The comprehensive treatment system for steel mill tail gas according to claim 1, characterized in that: The crystal quantity detector (4) comprises: A sampler (41) is provided inside the absorption tower (2); A sampling pipe (42) is connected to the sampler (41) and the absorption tower (2) to form a loop; A first electrically controlled sampling pump (43) is provided on the sampling pipeline (42); A diversion pipe (44) is connected to the sampling pipe (42) and the absorption tower (2) to form a loop, and a switching valve (441) is provided at the connection between the diversion pipe (44) and the sampling pipe (42); A metering box (45) is provided on the diversion pipe (44); an interception filter (46) is provided in the metering box (45); The second electrically controlled sampling pump (47) is provided on the diversion pipe (44) and is located behind the metering box (45).

6. The comprehensive treatment system for steel mill tail gas according to claim 1, characterized in that: A laser distance sensor (451) and a float (452) are provided inside the metering box (45).

7. The comprehensive treatment system for steel mill tail gas according to claim 6, characterized in that: Also includes: An electric heating wire (453) is provided on the outer wall of the metering box (452) or inside the metering box (452); The purge pipe (454) is connected to the metering box (452).

8. The comprehensive treatment system for steel mill tail gas according to claim 1, characterized in that: It also includes a regeneration module (6) connected to the absorption tower (2), and the regeneration module (6) is used to thermally decompose crystals generated in the absorption tower (2).

9. The comprehensive treatment system for steel mill tail gas according to claim 8, characterized in that: The regeneration module (6) includes: A pyrolysis tower (61) is connected to the absorption tower (2); Two groups of pyrolysis plates (62) are symmetrically and alternately arranged inside the pyrolysis tower (61); The end of the pyrolysis plate (62) away from the inner wall of the pyrolysis tower (61) is inclined toward the bottom of the pyrolysis tower (61).

10. The comprehensive treatment system for steel mill tail gas according to claim 9, characterized in that: There is a gap between one end of the pyrolysis plate (62) close to the inner wall of the pyrolysis tower (61) and the inner wall of the pyrolysis tower (61).

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