Calcium-based deacidification agent preparation device and control method

Abstract

The invention relates to the technical field of flue gas purification, in particular to a calcium-based deacidification agent preparation device and a control method. The device comprises a quicklime powder bin, a quicklime metering and feeding device and a three-stage dry digester which are connected through a pipeline, a steam exhaust outlet of the three-stage dry digester is communicated with the bottom of a bag-type dust collector of the digester, and a top outlet of the bag-type dust collector of the digester is connected with a dust removal fan of the digester. A slaked lime discharge port of the third-stage dry type digester is connected with a slaked lime discharge screw conveyor, an outlet of the slaked lime discharge screw conveyor is connected with a slaked lime ejector, and a gas inlet of the slaked lime ejector is connected with a slaked lime powder conveying fan. And the third-stage dry digester is communicated with the digestion water tank through a pipeline. According to the device, the raw material adaptability of a mechanical stirring type dry digestion process can be greatly improved, the whole digestion process is ensured to be in a set temperature window, the conversion rate and quality of a slaked lime product are improved, continuous operation of a quick lime digestion system is ensured, and the energy consumption and water consumption of the system are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas purification, and particularly to a calcium-based deacidifying agent preparation device and a control method thereof. Background Art

[0002] In dry and semi-dry flue gas deacidification process systems, the reaction activity of the deacidifying agent plays an important role, which directly affects the deacidification efficiency and the utilization rate of the deacidifying agent. Currently, in dry and semi-dry flue gas deacidification processes, slaked lime is mostly used as the deacidifying agent, which is transported from the slaked lime supplier to the site by a slaked lime tanker truck and stored in a powder bin for use. During this process, due to the reaction of slaked lime with CO2 in the air and moisture absorption and agglomeration, the reaction activity of slaked lime is reduced; moreover, the price of slaked lime in the market is higher than that of quicklime. Therefore, using low-cost quicklime to prepare slaked lime on-site can reduce the procurement cost of the deacidifying agent, improve the activity and utilization rate of slaked lime, and ensure the deacidification efficiency.

[0003] The digestion method of quicklime can be divided into a wet digestion process and a dry digestion process according to different water-lime ratios. Among them, the wet digestion process system is complex and the quality of slaked lime is not easy to control. Therefore, the dry digestion process is usually adopted in dry and semi-dry flue gas deacidification process systems. The dry digestion process can be further divided into a mechanical stirring dry digestion process and a gas flow agitation dry digestion process. Among them, the gas flow agitation dry digestion process has poor adaptability to the quality of raw material quicklime and high digestion energy consumption. Therefore, the mechanical stirring dry digestion process is mainly adopted in China.

[0004] The traditional mechanical stirring dry digestion process has the following problems:

[0005] (1) The purity, quality, and reaction activity of quicklime raw materials vary greatly. The existing mechanical stirring dry digestion process cannot adjust production parameters in real time. For different quicklime raw materials, due to certain differences in their average purity and reaction activity (the higher the reaction activity, the faster the digestion reaction and the shorter the time required for complete reaction), the digestion water volume, the digestion reaction heat per unit mass of quicklime, and the time required for the digestion reaction are different. If the mixing ratio of quicklime raw materials and water cannot be adjusted in real time accordingly or the residence time of the reactants (i.e., quicklime raw materials and slaked lime products, etc.) in the digester cannot be adjusted, the quicklime digester cannot always be in an efficient working state, resulting in low digestion reaction efficiency, high energy consumption, and limited production capacity improvement.

[0006] (2) A large amount of dusty steam is generated during the digestion process. To ensure the cleanliness of the on-site environment, a bag filter is usually used to purify the dusty steam. However, when the dusty steam is below the water dew point temperature, it has high viscosity and a large amount of moisture, which can cause failures in the bag filter and affect the continuous operation of the quicklime digestion system.

[0007] (3) Usually, after the dusty steam is purified by the bag filter, it is directly discharged into the ambient atmosphere. The heat of this part of the steam is not fully utilized, resulting in a waste of energy and an increase in production costs. SUMMARY OF THE INVENTION

[0008] In view of the above problems in the prior art, the present invention provides a calcium-based deacidifying agent preparation device and a control method.

[0009] To solve the above technical problems, the present application provides the following technical solutions:

[0010] A calcium-based deacidifying agent preparation device includes a quicklime powder silo, a quicklime metering feeder, and a three-stage dry digester connected by pipelines. The exhaust outlet of the three-stage dry digester is connected to the bottom of the digester bag filter. The top outlet of the digester bag filter is connected to the digester dust removal fan. The hydrated lime discharge port of the three-stage dry digester is connected to a hydrated lime discharge screw conveyor. The outlet of the hydrated lime discharge screw conveyor is connected to a hydrated lime injector. The gas inlet of the hydrated lime injector is connected to a hydrated lime powder conveying fan.

[0011] Among them, the three-stage dry digester is connected to a digestion water tank through a pipeline. The top of the digestion water tank is connected to a digestion water inlet pipe. The digestion water inlet pipe is connected to one end of a water supply control valve. The other end of the water supply control valve is connected to a water supply main pipe. The outlet of the steam inlet pipe extends below the liquid level of the digestion water tank. The steam inlet pipe is also connected to the outlet of the digester dust removal fan and a first steam control valve. The other end of the first steam control valve is connected to a steam main pipe. The inlet of the digestion bag filter is connected to a second steam control valve. The other end of the second steam control valve is connected to the steam main pipe.

[0012] Among them, the top of the three-stage dry digester is provided with a quicklime feeding inlet and an exhaust outlet. The bottom of the three-stage dry digester is provided with a slag discharge port and a hydrated lime discharge port. Inside the three-stage dry digester, a first-stage digestion unit, a second-stage digestion unit, and a third-stage digestion unit are sequentially arranged from top to bottom. The material flows through the first-stage digestion unit, the second-stage digestion unit, and the third-stage digestion unit in an "S" shape.

[0013] Among them, a first-stage digestion unit is provided with a first-stage digestion water supply nozzle group above it. The first-stage digestion water supply nozzle group includes a plurality of first-stage digestion water supply nozzles. The lower part of the first-stage digestion unit is provided with a first-stage digestion unit temperature measurement element group, which includes a plurality of first-stage digestion unit temperature measurement elements. The end of the first-stage digestion unit is provided with a first-stage digestion unit overflow plate. The first-stage digestion water supply nozzles in the first-stage digestion water supply nozzle group correspond one by one to the first-stage digestion unit temperature measurement elements in the first-stage digestion unit temperature measurement element group. Judging from the direction of material flow, the corresponding first-stage digestion unit temperature measurement element is located behind the corresponding first-stage digestion water supply nozzle.

[0014] Judging from the direction of material flow, a second-stage digestion water supply nozzle group is arranged above the first half of the second-stage digestion unit. The second-stage digestion water supply nozzle group includes 2 second-stage digestion water supply nozzles. The lower part of the first half of the second-stage digestion unit is provided with a second-stage digestion unit temperature measurement element group, which includes 2 second-stage digestion unit temperature measurement elements. The second-stage digestion water supply nozzles in the second-stage digestion water supply nozzle group correspond one by one to the second-stage digestion unit temperature measurement elements in the second-stage digestion unit temperature measurement element group. Judging from the direction of material flow, the corresponding second-stage digestion unit temperature measurement element is located behind the corresponding second-stage digestion water supply nozzle. The end of the second-stage digestion unit is provided with a second-stage digestion unit overflow plate. Judging from the direction of material flow, a digestion end temperature measurement element group is arranged at the lower part of the second half of the second-stage digestion unit, and the digestion end temperature measurement element group includes 2 digestion end temperature measurement elements.

[0015] The end of the third-stage digestion unit is provided with a third-stage digestion unit overflow plate.

[0016] Among them, the first-stage digestion unit and the second-stage digestion unit are of a double-shaft structure. Propeller-type blades are arranged at intervals on each stirring shaft, forming a spiral shape. The stirring blades on the two stirring shafts are arranged staggeredly. During stirring, it can not only provide strong mixing and shearing effects, but also push the material forward, and adopts frequency conversion control. The third-stage digestion unit is of a single-shaft structure, and continuous spiral blades are arranged on the stirring shaft, and frequency conversion control is adopted. The heights of the first-stage digestion unit overflow plate, the second-stage digestion unit overflow plate, and the third-stage digestion unit overflow plate can be adjusted, so as to adjust the effective capacity of each stage of digestion unit. Judging from the direction of material flow, the slag discharge port is arranged in front of the third-stage digestion unit overflow plate, and the slaked lime discharge port is arranged behind the third-stage digestion unit overflow plate. The slag discharge port is connected to a slag discharge pipe.

[0017] Among them, the outlet of the digestion water tank is connected to the digestion water pump through a pipeline. The digestion water pump is connected to the first-stage digestion water control valve group and the second-stage digestion water control valve group through pipelines. A digestion water flow measurement element is connected to the outlet pipeline of the digestion water pump. A digestion water temperature measurement element and a digestion water tank liquid level measurement element are connected to the digestion water tank. The digestion water pump is frequency-controlled. The outlets of the first-stage digestion water control valve group and the second-stage digestion water control valve group are respectively connected to the first-stage digestion water supply nozzle group and the second-stage digestion water supply nozzle group.

[0018] Among them, a dust collector pressure measurement element is arranged at the bottom inlet of the digester bag filter. A dust collector temperature measurement element is arranged at the top outlet of the digester bag filter. The digester dust removal fan is frequency-controlled. By controlling the operating frequency of the digester dust removal fan, the inlet pressure of the dust collector is about -3000 to -4000 Pa.

[0019] Among them, by adjusting the opening degree of the second steam control valve, the temperature at the outlet of the digester bag filter is controlled to be 15 - 20 °C higher than the water dew point temperature.

[0020] Among them, by adjusting the operating speed of the first-stage digestion unit, the mixing and stirring intensity and the material residence time are controlled, so that the digestion water and the quicklime material are in full contact, the material temperature is uniform, and at the same time, the surface of the material is continuously updated, exposing the undigested quicklime, and sufficient digestion reaction time is provided, which is beneficial to the digestion process. The residence time of the material in the first-stage digestion unit is 5 - 15 minutes, and the operating speed of the first-stage digestion unit is 15 - 25 r / min.

[0021] Preferably, when the operating parameters exceed the above range, that is, when the operating speed of the first-stage digestion unit is 15 r / min and the material residence time is still less than 5 min, manually adjust to increase the height of the overflow plate of the first-stage digestion unit. And when the operating speed of the digestion unit is 25 r / min and the material residence time is still greater than 15 minutes, manually adjust to reduce the height of the overflow plate of the first-stage digestion unit so that the material residence time is within the specified range.

[0022] By adjusting the operating speed of the second-stage digestion unit and the height of the overflow plate of the second-stage digestion unit, the residence time of the material in the second-stage digestion unit is controlled to be 10 - 30 minutes, and the operating speed of the second-stage digestion unit is 15 - 25 r / min.

[0023] The effective working volume of the second-stage digestion unit is 3 - 4 times that of the first-stage digestion unit.

[0024] By adjusting the opening degree of the first steam control valve, the temperature of the digestion water is controlled to be 65 - 80 °C, and the liquid level of the digestion water tank is adjusted by controlling the start and stop of the digestion water supply control valve.

[0025] By adjusting the working frequency of the digestion water pump, the flow rate of the digestion water is controlled so that the water-to-ash ratio during digestion is 1.3 - 2.0 (molar ratio).

[0026] By adjusting the opening degree of the first-stage digestion water control valve group, the temperature of the temperature measuring elements in each first-stage digestion unit during digestion is 105 - 130 °C. By adjusting the opening degree of the second-stage digestion water control valve group, the temperature of the temperature measuring elements in each second-stage digestion unit during digestion is 105 - 130 °C.

[0027] The completion degree of the digestion process is judged by the difference in the measured values of the temperature measuring elements in the digestion end temperature measuring element, and the working frequency of the second-stage digestion unit is adjusted accordingly to control the completion rate of the digestion process. Preferably, the temperature difference is 5 - 10 °C.

[0028] The control method of the calcium-based deacidifying agent preparation device of the present invention includes the following steps:

[0029] Step 1: Start the digestion dust removal fan, and control the operating frequency of the digestion dust removal fan according to the pressure at the inlet of the digestion bag filter. The pressure control value at the inlet of the digestion bag filter is -3000 Pa;

[0030] Step 2: Control the opening degree of the second steam control valve according to the temperature at the outlet of the digestion bag filter. The temperature control value at the outlet of the digestion bag filter is 15 - 20 °C higher than the water dew point;

[0031] Step 3: Control the opening and closing of the water supply control valve according to the liquid level of the digestion water tank;

[0032] Step 4: Control the opening degree of the first steam control valve according to the temperature of the digestion water in the digestion water tank;

[0033] Step 5: Calculate the required digestion water volume according to the flow rate of the quicklime metering feeding device;

[0034] Step 6: Control the working frequency of the digestion water pump according to the difference between the flow rate measured by the digestion water flow measuring element and the theoretically calculated digestion water volume;

[0035] Step 7: Adjust the corresponding first-stage digestion water control valve in the first-stage digestion water control valve group according to the difference between the temperature value measured by the first-stage digestion unit temperature measuring element in the first-stage digestion unit temperature measuring element group and the set temperature control target value, and then adjust the water supply volume of the corresponding first-stage digestion water supply nozzle to control the temperature target value at 105 - 130 °C. When the measured temperature is lower than 105 °C, increase the opening degree of the corresponding first-stage digestion water control valve. When the measured temperature is higher than 130 °C, decrease the opening degree of the corresponding first-stage digestion water control valve;

[0036] Step 8: Automatically adjust the working speed (15 - 25 r / min) of the first-stage digestion unit according to the set material residence time (5 - 15 minutes). When the operating parameters exceed the above range, manually adjust the height of the overflow plate of the first-stage digestion unit to meet the above parameter requirements;

[0037] Step 9: Adjust the corresponding secondary digestion water control valve in the secondary digestion water control valve group according to the difference between the temperature value measured by the secondary digestion unit temperature measuring element in the secondary digestion unit temperature measuring element group and the set temperature control target value, and then adjust the water supply volume of the corresponding secondary digestion water supply nozzle to control the temperature target value at 105 - 130 °C. When the measured temperature value is lower than 105 °C, increase the opening degree of the corresponding secondary digestion water control valve. When the measured temperature is higher than 130 °C, reduce the opening degree of the corresponding secondary digestion water control valve;

[0038] Step 10: Judge the completion rate of the digestion process according to the temperature difference measured by the digestion end temperature measuring element in the digestion end temperature measuring element group. When the temperature difference is less than the set value, it means that the digestion completion rate is qualified, and the working speed of the secondary digestion unit can be increased; when the temperature difference is greater than the set value, it means that the digestion completion rate is unqualified, and the working speed of the secondary digestion unit needs to be reduced; the working speed of the secondary digestion unit is (15 - 25 r / min). When the material residence time exceeds the set material residence time range (10 - 30 minutes), manually adjust the height of the overflow plate of the secondary digestion unit to meet the above parameter requirements;

[0039] Step 11: Adjust the working speed of the third-stage digestion unit according to the set slaked lime output.

[0040] Calculate the required digestion water volume according to the flow rate of the quicklime metering and feeding device as follows:

[0041]

[0042] In the formula:

[0043] is the required digestion water volume for the digestion process, kg / h;

[0044] is the digestion water-lime ratio (molar ratio), with a value of 1.3 - 2.0;

[0045] is the flow rate measured by the quicklime metering and feeding device, kg / h;

[0046] is the mass purity of quicklime, that is, the mass percentage of calcium oxide in unit mass of slaked lime, %;

[0047] is the molar mass of water, 18 g / mol;

[0048] is the molar mass of calcium oxide, 56 g / mol.

[0049] Compared with the prior art, the calcium-based deacidifying agent preparation device and control method of the present invention at least have the following beneficial effects:

[0050] (1) The calcium-based deacidifying agent preparation device and control method of the present invention can greatly improve the raw material adaptability of the mechanical stirring type dry digestion process. When the purity, quality, and reaction activity of the quicklime raw material vary greatly, the mixing ratio of the quicklime raw material and water can be automatically adjusted in real time, or the residence time of the reactants (i.e., the quicklime raw material and the slaked lime product, etc.) in the digester can be adjusted, improving the working efficiency of the quicklime digester, reducing energy consumption, and increasing production capacity.

[0051] (2) The calcium-based deacidifying agent preparation device of the present invention can automatically adjust the flow rate of each digestion water nozzle through the temperature measurement element group of the primary digestion unit and the temperature measurement element group of the secondary digestion unit, ensuring that the entire digestion process is within the set temperature window, and improving the conversion rate and quality of the slaked lime product.

[0052] (3) In the actual operation of the usual mechanical stirring type dry digestion process, due to reasons such as changes in the quicklime raw material and changes in the working load of the dry digester, the temperature of the dust-containing steam entering the bag filter of the digester is lower than the water dew point temperature, with greater viscosity and a large amount of moisture, causing bag filter failures and affecting the continuous operation of the quicklime digestion system. However, the present invention adds steam at the inlet of the bag filter of the digester, automatically adjusts the temperature at the outlet of the bag filter of the digester, ensures that the operating temperature of the bag filter of the digester is higher than the water dew point temperature, and guarantees the continuous operation of the quicklime digestion system.

[0053] (4) By introducing the dust-containing steam into the digestion water tank, the steam can be recovered as digestion water, reducing the water consumption of the system, and the heat of this part of the steam can be utilized, greatly reducing the energy consumption and water consumption of the system.

[0054] The following further describes the calcium-based deacidifying agent preparation device and control method of the present invention with reference to the accompanying drawings. Description of the Drawings

[0055] Figure 1 is a schematic diagram of the calcium-based deacidifying agent preparation device.

[0056] Figure 2 is a schematic diagram of the structure of a three-stage dry digester.

[0057] Figure 3 is Figure 2 the A-A sectional view of

[0058] Figure 4 It is a control logic diagram of a calcium-based deacidifying agent preparation device.

[0059] Among them, 1 - quicklime powder silo, 2 - quicklime metering and feeding device, 3 - three-stage dry digester, 4 - digester bag filter, 5 - digester dust removal fan, 6 - digestion water tank, 7 - digestion water pump, 8 - digestion water flow measuring element, 9 - first-stage digestion water control valve group, 10 - second-stage digestion water control valve group, 11 - hydrated lime discharge screw conveyor, 12 - hydrated lime powder conveying fan, 13 - hydrated lime injector, 14 - dust collector pressure measuring element, 15 - dust collector temperature measuring element, 16 - digestion water temperature measuring element, 17 - second steam control valve, 18 - first steam control valve, 19 - feed water control valve, 20 - steam main pipe, 21 - digestion water inlet pipe, 22 - steam inlet pipe, 23 - slag discharge pipe, 24 - feed water main pipe, 25 - liquid level measuring element;

[0060] 301 - quicklime feed inlet, 302 - first-stage digestion water spray nozzle, 303 - exhaust outlet, 304 - second-stage digestion water spray nozzle, 305 - first-stage digestion unit temperature measuring element, 306 - second-stage digestion unit temperature measuring element, 307 - slag discharge port, 308 - hydrated lime discharge port, 309 - first-stage digestion unit, 310 - second-stage digestion unit, 311 - third-stage digestion unit, 312 - first-stage digestion unit overflow plate, 313 - second-stage digestion unit overflow plate, 314 - third-stage digestion unit overflow plate, 315 - digestion end temperature measuring element. Specific implementation mode

[0061] Example 1

[0062] As Figures 1-3 shown, a calcium-based deacidifying agent preparation device includes a quicklime powder silo 1, a quicklime metering and feeding device 2, and a three-stage dry digester 3 connected by pipelines. The exhaust outlet 303 of the three-stage dry digester 3 is communicated with the bottom of the digester bag filter 4. The top outlet of the digester bag filter 4 is connected to the digester dust removal fan 5. The hydrated lime discharge port 308 of the three-stage dry digester 3 is connected to the hydrated lime discharge screw conveyor 11. The outlet of the hydrated lime discharge screw conveyor 11 is connected to the hydrated lime injector 13. The gas inlet of the hydrated lime injector 13 is connected to the hydrated lime powder conveying fan 12.

[0063] The three-stage dry digester 3 is connected to the digestion water tank 6 through a pipeline. The top of the digestion water tank 6 is connected to the digestion water inlet pipe 21. One end of the digestion water inlet pipe 21 is connected to one end of the feed water control valve 19, and the other end of the feed water control valve 19 is connected to the feed water main pipe 24. The outlet of the steam inlet pipe 22 extends below the liquid level of the digestion water tank 6. The steam inlet pipe 22 is simultaneously connected to the outlet of the digester dust removal fan 5 and the first steam control valve 18. The other end of the first steam control valve 18 is connected to the steam main pipe 20. The inlet of the digestion bag filter 4 is connected to a second steam control valve 17, and the other end of the second steam control valve 17 is connected to the steam main pipe 20.

[0064] As Figure 2 shown, the top of the three-stage dry digester 3 is provided with a quicklime feed inlet 301 and an exhaust outlet 303. The bottom of the three-stage dry digester 3 is provided with a slag discharge port 307 and a slaked lime discharge port 308. Inside the three-stage dry digester 3, a first-stage digestion unit 309, a second-stage digestion unit 310, and a third-stage digestion unit 311 are sequentially arranged from top to bottom. The material flows through the first-stage digestion unit 309, the second-stage digestion unit 310, and the third-stage digestion unit 311 in an "S" shape.

[0065] Above the first-stage digestion unit 309, a first-stage digestion water spray nozzle group is provided. The first-stage digestion water spray nozzle group includes a plurality of first-stage digestion water spray nozzles 302. Below the first-stage digestion unit 309, a first-stage digestion unit temperature measurement element group is provided. The first-stage digestion unit temperature measurement element group includes a plurality of first-stage digestion unit temperature measurement elements 305. At the end of the first-stage digestion unit 309, a first-stage digestion unit overflow plate 312 is provided. The first-stage digestion water spray nozzles 302 in the first-stage digestion water spray nozzle group and the first-stage digestion unit temperature measurement elements 305 in the first-stage digestion unit temperature measurement element group are in one-to-one correspondence. Judging from the direction of material flow, the corresponding first-stage digestion unit temperature measurement element is located behind the corresponding first-stage digestion water spray nozzle.

[0066] Judging from the direction of material flow, above the first half of the secondary digestion unit 310, a secondary digestion water supply nozzle group is arranged. The secondary digestion water supply nozzle group includes two secondary digestion water supply nozzles 304. At the lower part of the first half of the secondary digestion unit 310, a secondary digestion unit temperature measurement element group is provided. The secondary digestion unit temperature measurement element group includes two secondary digestion unit temperature measurement elements 306. The secondary digestion water supply nozzles 304 in the secondary digestion water supply nozzle group and the secondary digestion unit temperature measurement elements 306 in the secondary digestion unit temperature measurement element group are in one-to-one correspondence. Judging from the direction of material flow, the corresponding secondary digestion unit temperature measurement element is located behind the corresponding secondary digestion water supply nozzle. At the end of the secondary digestion unit 310, a secondary digestion unit overflow plate 313 is provided. Judging from the direction of material flow, at the lower part of the second half of the secondary digestion unit 310, a digestion end temperature measurement element group is arranged. The digestion end temperature measurement element group includes two digestion end temperature measurement elements 315.

[0067] At the end of the tertiary digestion unit 311, a tertiary digestion unit overflow plate 314 is provided.

[0068] As Figure 3 shown, the primary digestion unit 309 and the secondary digestion unit 310 are of a double-shaft structure. On each stirring shaft, propeller-type blades are arranged at intervals to form a spiral shape. The stirring blades on the two stirring shafts are arranged staggeredly. During stirring, it can not only provide strong mixing and shearing effects, but also push the material forward, and frequency conversion control is adopted. The tertiary digestion unit 311 is of a single-shaft structure, and continuous spiral blades are arranged on the stirring shaft, and frequency conversion control is adopted. The primary digestion unit overflow plate 312, the secondary digestion unit overflow plate 313, and the tertiary digestion unit overflow plate 314 can adjust the height, thereby adjusting the effective capacity of each digestion unit. Judging from the direction of material flow, the slag discharge port 307 is arranged in front of the tertiary digestion unit overflow plate 314, and the slaked lime discharge port 308 is arranged behind the tertiary digestion unit overflow plate 314. The slag discharge port 307 is connected to the slag discharge pipe 23.

[0069] The water outlet of the digestion water tank 6 is connected to the digestion water pump 7 through a pipeline. The digestion water pump 7 is connected to the primary digestion water control valve group 9 and the secondary digestion water control valve group 10 through pipelines. A digestion water flow measurement element 8 is connected to the outlet pipeline of the digestion water pump 7. A digestion water temperature measurement element 16 and a digestion water tank liquid level measurement element 25 are connected to the digestion water tank 6. The digestion water pump 7 is frequency conversion controlled. The outlets of the primary digestion water control valve group 9 and the secondary digestion water control valve group 10 are respectively connected to the primary digestion water supply nozzle group and the secondary digestion water supply nozzle group.

[0070] A dust collector pressure measuring element 14 is provided at the bottom inlet of the digester bag filter 4, and a dust collector temperature measuring element 15 is provided at the top outlet of the digester bag filter 4. The digester dust removal fan 5 is frequency-controlled. By controlling the operating frequency of the digester dust removal fan 5, the inlet pressure of the dust collector is about -3000 to -4000 Pa.

[0071] By adjusting the opening degree of the second steam control valve 17, the outlet temperature of the digester bag filter 4 is controlled to be 20 °C higher than the water dew point temperature.

[0072] By adjusting the operating speed of the primary digestion unit 309, the mixing and stirring intensity and the residence time of the material are controlled, so that the digestion water and the quicklime material are in full contact, the material temperature is uniform, and at the same time, the surface of the material is continuously updated, exposing the undigested quicklime, and sufficient digestion reaction time is provided, which is beneficial to the digestion process. The residence time of the material in the primary digestion unit 309 is 5 to 15 minutes, and the operating speed of the primary digestion unit 309 is 15 to 25 r / min.

[0073] By adjusting the operating speed of the secondary digestion unit 310 and the height of the overflow plate 313 of the secondary digestion unit, the residence time of the material in the secondary digestion unit 310 is controlled to be 10 to 30 minutes, and the operating speed of the secondary digestion unit 310 is 15 to 25 r / min.

[0074] The effective working volume of the secondary digestion unit 310 is 4 times that of the primary digestion unit 309.

[0075] By adjusting the opening degree of the first steam control valve 18, the temperature of the digestion water is controlled to be 75 °C, and the liquid level of the digestion water tank is adjusted by controlling the start and stop of the digestion water supply control valve 19.

[0076] By adjusting the operating frequency of the digestion water pump 7, the flow rate of the digestion water is controlled so that the water-to-ash ratio in the digestion process is 1.6 (molar ratio).

[0077] By adjusting the opening degree of the primary digestion water control valve group 9, the temperature of each primary digestion unit temperature measuring element 305 in the digestion process is 105 to 130 °C.

[0078] By adjusting the opening degree of the secondary digestion water control valve group 10, the temperature of each secondary digestion unit temperature measuring element 306 in the digestion process is 105 to 130 °C.

[0079] The completion degree of the digestion process is judged by the difference in the measured values of the temperature measuring elements in the digestion end temperature measuring element 315, and the working frequency of the secondary digestion unit 310 is adjusted accordingly to control the completion rate of the digestion process. Preferably, the temperature difference is 5 °C.

[0080] Example 2

[0081] The control method of the calcium-based deacidifying agent preparation device of Example 1 is as Figure 4 shown, and includes the following steps:

[0082] Step 1: Start the digester dust removal fan 5, and control the operating frequency of the digester dust removal fan 5 according to the pressure at the inlet of the digester bag filter 4. The pressure control value at the inlet of the digester bag filter 4 is -3000 Pa;

[0083] Step 2: Control the opening degree of the second steam control valve 17 according to the temperature at the outlet of the digester bag filter 4. The temperature control value at the outlet of the digester bag filter 4 is 20°C higher than the water dew point;

[0084] Step 3: Control the opening and closing of the feed water control valve 19 according to the liquid level of the digestion water tank 6;

[0085] Step 4: Control the opening degree of the first steam control valve 18 according to the temperature of the digestion water in the digestion water tank 6;

[0086] Step 5: Calculate the required digestion water volume according to the flow rate of the quicklime metering and feeding device 2;

[0087] Step 6: Control the operating frequency of the digestion water pump 7 according to the difference between the flow rate measured by the digestion water flow measuring element 8 and the theoretically calculated digestion water volume;

[0088] Step 7: Adjust the corresponding primary digestion water control valve in the primary digestion water control valve group 9 according to the difference between the temperature value measured by the primary digestion unit temperature measuring element 305 in the primary digestion unit temperature measuring element group and the set temperature control target value, and then adjust the water supply volume of the corresponding primary digestion water supply nozzle to control the temperature target value at 105 - 130°C. When the measured temperature is lower than 105°C, increase the opening degree of the corresponding primary digestion water control valve. When the measured temperature is higher than 130°C, decrease the opening degree of the corresponding primary digestion water control valve;

[0089] Step 8: Automatically adjust the operating speed (15 - 25 r / min) of the primary digestion unit 309 according to the set material residence time (10 minutes). When the operating parameters exceed the above range, the height of the overflow plate 312 of the primary digestion unit can be manually adjusted to meet the above parameter requirements;

[0090] Step 9: Adjust the corresponding secondary digestion water control valve in the secondary digestion water control valve group 10 according to the difference between the temperature value measured by the secondary digestion unit temperature measuring element 306 in the secondary digestion unit temperature measuring element group and the set temperature control target value, and then adjust the water supply amount of the corresponding secondary digestion water supply nozzle to control the temperature target value at 105 - 130 °C. When the measured temperature value is lower than 105 °C, increase the opening degree of the corresponding secondary digestion water control valve; when the measured temperature is higher than 130 °C, reduce the opening degree of the corresponding secondary digestion water control valve;

[0091] Step 10: Judge the completion rate of the digestion process according to the temperature difference measured by the digestion end temperature measuring element 315 in the digestion end temperature measuring element group. When the temperature difference is less than the set value, it indicates that the digestion completion rate is qualified, and the working speed of the secondary digestion unit 310 can be increased; when the temperature difference is greater than the set value, it indicates that the digestion completion rate is unqualified, and the working speed of the secondary digestion unit 310 needs to be reduced; the working speed of the secondary digestion unit is (15 - 25 r / min). When the material residence time exceeds the set material residence time range (20 minutes), the height of the secondary digestion unit overflow plate 313 can be manually adjusted to meet the above parameter requirements;

[0092] Step 11: Adjust the working speed of the tertiary digestion unit 311 according to the set slaked lime output.

[0093] Calculate the required digestion water volume according to the flow rate of the quicklime metering feeding device according to the following formula:

[0094]

[0095] In the formula:

[0096] is the required digestion water volume for the digestion process, kg / h;

[0097] is the digestion water - lime ratio (molar ratio), with a value of 1.6;

[0098] is the flow rate measured by the quicklime metering feeding device, kg / h;

[0099] is the mass purity of quicklime, that is, the mass percentage of calcium oxide in unit - mass slaked lime, %;

[0100] is the molar mass of water, 18 g / mol;

[0101] is the molar mass of calcium oxide, 56 g / mol.

[0102] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A calcium-based deacidifying agent preparation device, characterized in that: It includes a quicklime powder silo (1), a quicklime metering and feeding device (2), and a three-stage dry digester (3) connected by pipelines. The exhaust outlet (303) of the three-stage dry digester (3) is communicated with the bottom of the digester bag filter (4). The top outlet of the digester bag filter (4) is connected to the digester dust removal fan (5). The hydrated lime discharge port (308) of the three-stage dry digester (3) is connected to the hydrated lime discharge screw conveyor (11). The outlet of the hydrated lime discharge screw conveyor (11) is connected to the hydrated lime injector (13). The gas inlet of the hydrated lime injector (13) is connected to the hydrated lime powder conveying fan (12). The three-stage dry digester (3) is communicated with the digestion water tank (6) through a pipeline.

2. The calcium-based deacidifying agent preparation device according to claim 1, characterized in that: The top of the digestion water tank (6) is connected to the digestion water inlet pipe (21). The digestion water inlet pipe (21) is connected to one end of the water supply control valve (19). The other end of the water supply control valve (19) is connected to the water supply main pipe (24). The outlet of the steam inlet pipe (22) extends below the liquid level of the digestion water tank (6). The steam inlet pipe (22) is simultaneously connected to the outlet of the digester dust removal fan (5) and the first steam control valve (18). The other end of the first steam control valve (18) is connected to the steam main pipe (20). The inlet of the digestion bag filter (4) is communicated with a second steam control valve (17). The other end of the second steam control valve (17) is connected to the steam main pipe (20).

3. The calcium-based deacidifying agent preparation device according to claim 1, wherein: The top of the three-stage dry digester (3) is provided with a quicklime feeding inlet (301) and an exhaust outlet (303). The bottom of the three-stage dry digester (3) is provided with a slag discharge port (307) and a hydrated lime discharge port (308). Inside the three-stage dry digester (3), a first-stage digestion unit (309), a second-stage digestion unit (310), and a third-stage digestion unit (311) are successively arranged from top to bottom. The material flows through the first-stage digestion unit (309), the second-stage digestion unit (310), and the third-stage digestion unit (311) in an "S" shape.

4. The calcium-based deacidifying agent preparation device according to claim 3, characterized in that: Above the first-stage digestion unit (309), a first-stage digestion water spraying nozzle group is provided. The first-stage digestion water spraying nozzle group includes a plurality of first-stage digestion water spraying nozzles (302). Below the first-stage digestion unit (309), a first-stage digestion unit temperature measuring element group is provided. The first-stage digestion unit temperature measuring element group includes a plurality of first-stage digestion unit temperature measuring elements (305). At the end of the first-stage digestion unit (309), a first-stage digestion unit overflow plate (312) is provided; Above the first half of the secondary digestion unit (310), a secondary digestion water supply nozzle group is arranged. The secondary digestion water supply nozzle group includes a plurality of secondary digestion water supply nozzles (304). At the lower part of the first half of the secondary digestion unit (310), a secondary digestion unit temperature measurement element group is provided. The secondary digestion unit temperature measurement element group includes a plurality of secondary digestion unit temperature measurement elements (306). At the end of the secondary digestion unit (310), a secondary digestion unit overflow plate (313) is provided. At the lower part of the second half of the secondary digestion unit (310), a digestion end temperature measurement element group is arranged. The digestion end temperature measurement element group includes a plurality of digestion end temperature measurement elements (315); At the end of the tertiary digestion unit (311), a tertiary digestion unit overflow plate (314) is provided.

5. The calcium-based deacidifying agent preparation device according to claim 4, characterized in that: The primary digestion unit (309) and the secondary digestion unit (310) are of a double-shaft structure. Propeller-type blades are arranged at intervals on each stirring shaft, forming a spiral shape. The stirring blades on the two stirring shafts are arranged staggeredly; The tertiary digestion unit (311) is of a single-shaft structure, and continuous spiral blades are arranged on the stirring shaft.

6. The calcium-based deacidifying agent preparation device according to claim 5, characterized in that: The heights of the primary digestion unit overflow plate (312), the secondary digestion unit overflow plate (313), and the tertiary digestion unit overflow plate (314) are all adjustable, so as to adjust the effective capacity of each digestion unit.

7. The calcium-based deacidifying agent preparation device according to claim 6, characterized in that: The slag discharge port (307) is arranged in front of the tertiary digestion unit overflow plate (314), and the slaked lime discharge port (308) is arranged behind the tertiary digestion unit overflow plate (314). The slag discharge port (307) is connected to the slag discharge pipe (23).

8. The calcium-based deacidifying agent preparation device according to claim 7, characterized in that: The water outlet of the digestion water tank (6) is connected to the digestion water pump (7) through a pipeline. The digestion water pump (7) is connected to the primary digestion water control valve group (9) and the secondary digestion water control valve group (10) through pipelines. A digestion water flow measurement element (8) is connected to the outlet pipeline of the digestion water pump (7). A digestion water temperature measurement element (16) and a digestion water tank liquid level measurement element (25) are connected to the digestion water tank (6). The outlets of the primary digestion water control valve group (9) and the secondary digestion water control valve group (10) are respectively connected to the primary digestion water supply nozzle group and the secondary digestion water supply nozzle group.

9. The calcium-based deacidifying agent preparation device according to claim 1, wherein: At the bottom inlet of the digester bag filter (4), a dust collector pressure measurement element (14) is provided. At the top outlet of the digester bag filter (4), a dust collector temperature measurement element (15) is provided.

10. The control method of the calcium-based deacidifying agent preparation device according to any one of claims 1-9, characterized in that, Including the following steps: Step 1: Start the digester dust removal fan, and control the operating frequency of the digester dust removal fan according to the pressure at the inlet of the digester bag filter. The pressure control value at the inlet of the digester bag filter is -3000 Pa; Step 2: Control the opening degree of the second steam control valve according to the temperature at the outlet of the digester bag filter. The temperature control value at the outlet of the digester bag filter is 15 - 20 °C higher than the water dew point; Step 3: Control the opening and closing of the water supply control valve according to the liquid level of the digestion water tank; Step 4: Control the opening degree of the first steam control valve according to the digestion water temperature of the digestion water tank; Step 5: Calculate the required digestion water volume according to the flow rate of the quicklime metering feeding device; Step 6: Control the operating frequency of the digestion water pump according to the difference between the flow rate measured by the digestion water flow measuring element and the calculated theoretical digestion water volume; Step 7: Adjust the corresponding primary digestion water control valve in the primary digestion water control valve group according to the difference between the temperature value measured by the primary digestion unit temperature measuring element in the primary digestion unit temperature measuring element group and the set temperature control target value, and then adjust the water supply volume of the corresponding primary digestion water supply nozzle to control the temperature target value at 105 - 130 °C. When the measured temperature is lower than 105 °C, increase the opening degree of the corresponding primary digestion water control valve; when the measured temperature is higher than 130 °C, reduce the opening degree of the corresponding primary digestion water control valve; Step 8: Automatically adjust the operating speed of the primary digestion unit according to the set material residence time. When the operating parameters exceed the range, manually adjust the height of the overflow plate of the primary digestion unit to meet the parameter requirements; Step 9: Adjust the corresponding secondary digestion water control valve in the secondary digestion water control valve group according to the difference between the temperature value measured by the secondary digestion unit temperature measuring element in the secondary digestion unit temperature measuring element group and the set temperature control target value, and then adjust the water supply volume of the corresponding secondary digestion water supply nozzle to control the temperature target value at 105 - 130 °C. When the measured temperature is lower than 105 °C, increase the opening degree of the corresponding secondary digestion water control valve; when the measured temperature is higher than 130 °C, reduce the opening degree of the corresponding secondary digestion water control valve; Step 10: Judge the completion rate of the digestion process according to the temperature difference measured by the digestion end temperature measuring element in the digestion end temperature measuring element group. When the temperature difference is less than the set value, it indicates that the digestion completion rate is qualified, and the operating speed of the secondary digestion unit can be increased; when the temperature difference is greater than the set value, it indicates that the digestion completion rate is unqualified, and the operating speed of the secondary digestion unit needs to be reduced; the operating speed of the secondary digestion unit is 15 - 25 r / min. When the material residence time exceeds the set material residence time range, the height of the overflow plate of the secondary digestion unit can be manually adjusted to meet the parameter requirements; Step 11: Adjust the operating speed of the tertiary digestion unit according to the set slaked lime output; Among them, the digestion water volume required is calculated according to the flow rate of the quicklime metering and feeding device according to the following formula: ， In the formula: The amount of digestion water required for the digestion process, kg / h; To digest the water-cement ratio, the molar ratio is taken as 1.3 to 2.0; is the flow rate measured by the quicklime metering and feeding device, kg / h; It is the mass purity of quicklime, that is, the mass percentage of calcium oxide in hydrated lime per unit mass, %. is the molar mass of water, 18 g / mol; is the molar mass of calcium oxide, 56 g / mol.

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