Device for preparing flue gas desulfurizer by using alkaline residues

Abstract

The utility model discloses a device for preparing a flue gas desulfurizing agent by utilizing alkaline residues, which comprises an alkaline residue pulping tank, a stirring tank, a settling tank, a filter press, a turning and throwing crusher for treating solids in the filter press, a flour mill, a powder concentrator, a dust collector and an induced draft fan which are sequentially communicated through a slurry pump, and an air feeder is communicated with the interior of the flour mill through a hot blast stove. And the air feeder and the induced draft fan are respectively communicated with the two heat exchange pipelines of the air-smoke heat exchanger. The high-quality coal-fired power plant flue gas desulfurization powder which is low in energy consumption, low in chlorine ion content, high in activity and wide in particle size adjusting range can be prepared by efficiently utilizing stock alkaline residues, and the problem of resource utilization of the alkaline residues is effectively solved.

Description

Technical Field

[0001] The utility model relates to a comprehensive utilization method for solid waste of alkali residue generated in the ammonia-alkali process for producing soda ash, specifically a device for preparing a flue gas desulfurizer by using alkali residue, belonging to the technical field of solid waste utilization. Background Technique

[0002] Alkali residue is a solid waste generated in the process of producing soda ash by the ammonia-alkali method. For a long time, the ammonia-alkali method, as the main method for producing soda ash, has been adopted by most domestic alkali plants. According to statistics, for every 1 ton of soda ash produced, 300 kg of alkali residue needs to be discharged accordingly. Its main chemical components include calcium carbonate, calcium sulfate, calcium chloride, and calcium oxide, etc. Generally, alkali residue contains 60% - 70% water, and the solid components mostly exist in the form of particles. The particles with a particle size between 2.0 μm and 25.0 μm account for more than 60%. The particle size is extremely fine, the specific surface area is relatively large, and it has certain colloidal properties, making it difficult to dehydrate and utilize. In addition, the content of soluble chlorides (such as NaCl, CaCl2, etc.) in alkali residue is relatively high, accounting for 20% - 40% in the dry basis, with certain corrosiveness, making its reuse in industrial production face great difficulties.

[0003] In the development process of the alkali residue treatment industry, in the initial stage, due to technical and equipment limitations, alkali residue was mainly simply stacked or discharged into the environment, causing serious environmental pollution. Solid residue methods such as building dams to store slag have caused long-term stacking of alkali residue, not only occupying a large amount of land resources, but also bringing a series of environmental problems.

[0004] In addition to building dams for stacking, major alkali plants have also actively explored the resource utilization of alkali residue, and put forward application ideas such as using alkali residue to fill the sea and create land, using it as engineering backfill soil, or developing by-products using alkali residue such as manufacturing new building materials, flue gas desulfurizer, asphalt concrete filler, etc., but all encountered technical problems such as high moisture content of alkali residue, difficulty in decomposing chlorides, and sticky paste that is not easy to separate.

[0005] Due to the strong alkalinity, high calcium carbonate content, and large activity of alkali residue, it has good economic and environmental benefits when used to prepare flue gas desulfurizer for coal-fired power plants. According to the conveying method, there are currently two production routes for preparing flue gas desulfurizer from alkali residue:

[0006] One is to use the alkali residue waste liquid generated in the production process of the alkali plant, through processes such as sand sedimentation, thickening, and chlorine reduction, to prepare a liquid desulfurizer, which is transported to the thermal power plant for use by an alkali residue pump or a tanker truck. The process flow diagram is as Figure 1 shown.

[0007] The principle of alkali slag washing is similar to that of salt mud washing. The alkali slag is transported from the slag yard to the factory and thickened by the thickener. It then enters from the top layer of the mud washing barrel. Clarified return water is added to the center sleeve and the bottom layer for reverse contact washing. The washed alkali slag is discharged into the waste mud tank through the mud discharge pipeline at the bottom of the barrel, and the washing water enters the pump station. On this basis, Chinese patent CN104857831B proposes a alkali slag liquid desulfurizer preparation device and method to ensure good dispersion, activity and fluidity of liquid desulfurizer particles. The use of liquid transportation requires the use of existing process equipment in the alkali plant, and generally requires a close distance to the power plant. It is suitable for the treatment of waste liquid discharged during the production process of the alkali plant, but it is not applicable to the treatment of a large amount of solid alkali slag stored in the alkali slag dam.

[0008] Another route for preparing flue gas desulfurization agent is to filter the waste alkali residue of the alkali plant to form dry residue, mix it with other powders and additives, and prepare flue gas desulfurization powder after drying, grinding and other processes. In view of the fact that the current wet desulfurization system of power plants generally directly purchases limestone powder for direct slurrying, this method can achieve seamless connection between the resource utilization of alkali residue and the existing desulfurization process, without increasing the investment in equipment transformation on the power plant side, while solving the problem of limited transportation distance of desulfurizers, which can reduce the difficulty of subsequent market promotion and application. Chinese patent CN101870900B uses industrial waste alkali residue as the main raw material, adds light-burned dolomite powder, mullite powder and other additives, and prepares desulfurization powder; Chinese patent CN103157652B discloses a method for manufacturing desulfurizers from solid waste generated in the soda ash plant industry, including specific steps such as mixing, impurity removal, drying, crushing, grinding, etc., which can produce high-quality limestone powder desulfurizer with high CaO purity, high activity and few impurities. However, this method is only effective for the chloride soluble salts (NaCl, CaCl 2 The chloride ions in the slurry after the desulfurizer is slurried will not only cause certain corrosion to the internal components of the desulfurization tower and the slurry circulation system, but will also increase the output of desulfurization wastewater in the power plant and increase the burden of sewage treatment on the enterprise.

[0009] In summary, for the existing technology of preparing flue gas desulfurization agent from alkali slag, the use of alkali slag waste liquid to prepare liquid desulfurization agent requires the use of existing process equipment in the alkali plant, and liquid transportation generally requires a close distance to the power plant, which is not suitable for solid storage of alkali slag treatment and long-distance transportation; and the existing flue gas desulfurization powder preparation technology cannot completely remove the chloride soluble salts contained in the alkali slag, which not only causes certain corrosion to the internal components of the desulfurization tower and the slurry circulation system, affecting the safety and stability of the original desulfurization system of the power plant, but also increases the output of desulfurization wastewater from the power plant, increasing the burden of sewage treatment on the enterprise.

[0010] Currently, there is a lack of technical research on preparing flue gas desulfurization agents from stockpile alkali residue after chlorine removal by water washing. Moreover, the existing technology for preparing flue gas desulfurization agent powder from alkali residue also lacks energy-saving measures, resulting in relatively high drying energy consumption, which is not conducive to the large-scale popularization and application of this technology. Utility Model Content

[0011] The technical problem to be solved by this utility model is to provide a device and method for preparing flue gas desulfurization agents using alkali residue, so as to solve the blank in the current field of using stockpile alkali residue to efficiently remove the chlorides contained in the alkali residue for preparing flue gas desulfurization powder.

[0012] To solve the above problems, this utility model provides a device for preparing flue gas desulfurization agents using alkali residue, which includes an alkali residue pulping tank, a stirring tank, a sedimentation tank, and a filter press connected in sequence by a slurry pump, a turning and crushing machine, a grinding machine, a powder separator, a dust collector, and an induced draft fan for processing the solids in the filter press. The blower is connected to the inside of the grinding machine through a hot blast stove, and the blower and the induced draft fan are respectively connected to two heat exchange pipelines of the air-smoke heat exchanger.

[0013] Preferably, the stirring tank and the sedimentation tank are respectively connected to the medium water circulation pump through a stirring tank water inlet regulating valve and a sedimentation tank water inlet regulating valve.

[0014] Preferably, a medicine adding tank is connected to the stirring tank.

[0015] Preferably, at least one surplus water pump is connected to the bottom of the sedimentation tank, and one of the surplus water pumps is connected to the alkali residue pulping tank.

[0016] Preferably, a tail water pump for draining water is connected to the bottom of the filter press.

[0017] Preferably, a belt conveyor, a hoist, and a feeder are sequentially arranged between the turning and crushing machine and the grinding machine. A feed bin is arranged above the feeder, and the hoist is connected to the feed bin.

[0018] Preferably, the top of the grinding machine is connected to the top of the powder separator, and the bottom of the powder separator is connected to the middle of the grinding machine to form a loop; the hot blast stove is connected to both sides of the bottom of the grinding machine, so that convection is formed inside the grinding machine.

[0019] Preferably, the air-smoke heat exchanger includes a heat exchanger housing. Gravity heat pipes and heat exchange fins are arranged inside the heat exchanger housing. The inside of the heat exchanger housing is divided into two upper and lower heat exchange pipelines. The upper part is an air duct, and the lower part is a flue; two ash hoppers are arranged at the bottom of the heat exchanger housing, and a discharge pipe is arranged at the bottom of each ash hopper, and a discharge valve is arranged on the discharge pipe.

[0020] Preferably, in the air-smoke heat exchanger, the outlet end of the heat exchange pipeline connected to the induced draft fan is connected to the chimney, and the inlet end of the heat exchange pipeline connected to the blower is connected to the atmosphere.

[0021] The utility model provides a device for preparing a flue gas desulfurization agent by using alkali residue. Aiming at the stored alkali residue in the slag pool, through processes such as alkali residue excavation and transportation, stirring, dosing, precipitation, and pressure filtration, the chlorides contained in the alkali residue are efficiently removed to form solid dry slag filter blocks. Then, through processes such as turning, breaking, drying, grinding, powder selection, and dust collection, high-quality flue gas desulfurization powder for coal-fired power plants with low energy consumption, low chloride ion content, high activity, and a wide particle size adjustment range is prepared, so as to solve the technical problems in the prior art such as high content of chloride soluble salts, large energy consumption for drying and crushing, and poor dispersion of powder particles, and the problem that it is not conducive to the large-scale popularization and application of the technology for preparing flue gas desulfurization powder from alkali residue in the follow-up.

[0022] The utility model can efficiently utilize the stored alkali residue to prepare high-quality flue gas desulfurization powder for coal-fired power plants with low energy consumption, low chloride ion content, high activity, and a wide particle size adjustment range, and effectively solve the problem of the resource utilization of alkali residue.

[0023] Compared with the prior art, the beneficial effects of the utility model are as follows:

[0024] (1) Aiming at the problem of the resource treatment of the stored alkali residue, it does not depend on the original production process of ammonia-alkali method for making soda ash.

[0025] (2) The chloride soluble salts contained in the alkali residue are efficiently removed, and the prepared desulfurization agent will not cause system corrosion and an increase in the production of desulfurized wastewater due to the problem of excessive chloride ions during the desulfurization operation.

[0026] (3) A variety of energy-saving and consumption-reducing measures are coupled, and the system operation energy consumption is relatively low.

[0027] (4) The particle size adjustment range of the desulfurization powder is wide, and desulfurization powder with high reaction activity can be produced.

[0028] (5) The produced desulfurized gypsum has a relatively high purity, can meet the requirements of the building materials and cement industries, and is conducive to popularization and application.

[0029] The utility model adopts an automatic control system, has the ability to operate continuously for a long time, can be unattended, and meets the requirements of large-scale treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a process flow chart of the existing alkali residue waste liquid treatment process;

[0031] Figure 2 It is a schematic diagram of the device for preparing a flue gas desulfurization agent by using alkali residue provided by the utility model;

[0032] Figure 3 It is a schematic diagram of the structure of a heat pipe type air and flue gas heat exchanger. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To make the present utility model more obvious and understandable, a preferred embodiment is hereby described in detail in conjunction with the accompanying drawings as follows.

[0034] As Figure 2 shown, a device for preparing a flue gas desulfurization agent using alkali residue provided by the present utility model includes a slurry preparation tank 1 for alkali residue, a first slurry pump 2, a mixing tank 3, a second slurry pump 4, a sedimentation tank 5, a third slurry pump 6, a filter press 7, a turning crusher 8 for treating the solids in the filter press 7, a grinding mill 20, a classifier 21, a dust collector 22, a draft fan 23. A blower 26 is connected to the inside of the grinding mill 20 through a hot blast stove 27, and the blower 26 and the draft fan 23 are respectively connected to two heat exchange pipes of a flue gas heat exchanger 24.

[0035] The mixing tank 3 and the sedimentation tank 5 are respectively connected to a medium water circulation pump 12 through a mixing tank water inlet regulating valve 13 and a sedimentation tank water inlet regulating valve 14.

[0036] The mixing tank 3 is connected with a chemical dosing tank 15.

[0037] Two residue pumps are connected to the bottom of the sedimentation tank 5. The first residue pump 16 is connected to the slurry preparation tank 1 for alkali residue, and the second residue pump 17.

[0038] A tail water pump 18 for draining water is connected to the bottom of the filter press 7.

[0039] A belt conveyor 9, an elevator 10, and a feeder 19 are sequentially arranged between the turning crusher 8 and the grinding mill 20. A feed bin 11 is arranged above the feeder 19, and the elevator 10 is connected to the feed bin 11.

[0040] The top of the grinding mill 20 is connected to the top of the classifier 21, and the bottom of the classifier 21 is connected to the middle of the grinding mill 20 to form a loop; the hot blast stove 27 is connected to both sides of the bottom of the grinding mill 20, so that a convection is formed inside the grinding mill 20.

[0041] As Figure 3 shown, the flue gas heat exchanger 24 includes a heat exchanger housing 2401. Gravity heat pipes 2402 and heat exchange fins 2403 are arranged inside the heat exchanger housing 2401. The inside of the heat exchanger housing 2401 is divided into upper and lower heat exchange pipes. The upper part is an air duct 2405, and the lower part is a flue duct 2406; two ash hoppers 2407 are arranged at the bottom of the heat exchanger housing 2401. An ash discharge pipe 2409 is arranged at the bottom of each ash hopper 2407, and an ash discharge valve 2408 is arranged on the ash discharge pipe 2409. In the flue gas heat exchanger 24, the outlet end of the heat exchange pipe connected to the draft fan 23 is connected to a chimney 25, and the inlet end of the heat exchange pipe connected to the blower 26 is connected to the atmosphere.

[0042] A method for preparing a flue gas desulfurization agent using alkali residue includes the following steps:

[0043] S1: Pump the excess water in the supernatant of the sedimentation tank 5 to the alkali residue pulping tank 1; through the mixing and crushing of the mobile alkali residue stirring and crushing device inside the alkali residue pulping tank 1, a liquid slurry is formed; the slurry is pumped to the stirring tank 3 by a slurry pump;

[0044] S2: Measure and read the monitoring value of the on-line solid content detection device in the stirring tank 3; control the water inlet into the stirring tank 3 to adjust the solid content to the set value; add solid salt agents and dispersing agents as needed, and continuously stir for the required reaction time;

[0045] S3: Pump the alkali residue slurry in the stirring tank 3 to the sedimentation tank 5 by a slurry pump for standing, homogenizing and sedimentation; on-line monitor the conductivity of the supernatant, control the water inlet into the sedimentation tank 5 to reduce the conductivity of the supernatant to the set value; when the solid content of the bottom slurry rises to the set value, start the slurry pump connected to the filter press 7 until the solid content of the bottom slurry drops to the lowest lower limit value, and then turn off the slurry pump;

[0046] S4: Pump the slurry in the sedimentation tank 5 to the filter press 7 by a slurry pump, and the filter press 7 presses and dehydrates the slurry to form alkali residue blocks; the alkali residue blocks enter the turning and crushing machine 8 for primary crushing to form alkali residue particles; the alkali residue particles are spread out for drying and turned over regularly to reduce the moisture content of the alkali residue particles to the required value;

[0047] S5: Send the dried alkali residue particles after drying to the grinding disc of the grinding machine 20, and the grinding machine 20 grinds the dry slag machine particles into fine powder. The hot air introduced dries the fine powder and carries the fine powder to the classifier 21;

[0048] S6: The qualified fine powder screened out by the classifier 21 is carried by the air flow to the dust collector 22, and the dust collector 22 captures the fine powder into the ash bin at the lower part of the dust collector 22; the purified flue gas after dust removal passes through the smoke exhaust port at the upper part of the dust collector 22 and the flue connected thereto and enters the induced draft fan 23;

[0049] S7: Send the purified flue gas after dust removal to the air and flue gas heat exchanger 24 by the induced draft fan 23; in the air and flue gas heat exchanger 24, the hot flue gas exchanges heat with the cold air; the flue gas after releasing heat is discharged into the atmosphere, and the air after absorbing heat is sent into the hot blast stove by the blower 26. The air is reheated for the second time in the hot blast stove 26 and heated to the temperature required for drying the particles entering the grinding machine 20; the hot air is sent into the grinding machine 20 by the blower 26 to dry the alkali residue powder in the grinding machine 20.

[0050] Example

[0051] In this example, the device for preparing the flue gas desulfurization agent by using alkali residue includes the following components:

[0052] Alkali residue pulping system. The alkali residue pulping tank is located in the slag pond piled up by the alkali residue dam body. Through hydraulic dredging equipment, it is prepared into alkali residue slurry convenient for liquid transportation, including surplus water outlet, inlet of the first slurry pump, and stirring and crushing device for forming slurry; the inlet of the first slurry pump is provided with a filtering device to filter out larger-sized impurities during the slurry suction process; the stirring and crushing device is movable, such as a cutter suction dredger type, a crawler type, etc.;

[0053] Stirring reaction system, used for proportioning and storing alkali residue slurry with appropriate solid content concentration, and making the substances in the tank mix evenly and the soluble substances dissolve fully through stirring, including a stirring tank and a stirring device, a first slurry pump, a water inlet regulating valve for the stirring tank, a chemical dosing tank, and accessory slurry inlet pipes and water inlet pipes, etc.; the first slurry pump is frequency-regulated, and an on-line solid content detection device is arranged in the stirring tank, which is connected to the automatic control system platform. By controlling the water inlet regulating valve and the flow rate of the first slurry pump, the solid content of the slurry in the stirring tank is adjusted; the chemical in the chemical dosing tank is a chemical for solidifying salts and dispersing, which plays the role of solidifying Cl - and preventing the slurry from polymerizing prematurely; preferably, the slurry inlet of the stirring tank can be set to multiple ones, flowing in at different angles around the stirring tank to further promote the mixing of the slurry and save stirring energy consumption;

[0054] Slurry precipitation system, realizing the primary liquid-solid separation of alkali residue slurry through static settlement, including a sedimentation tank, a water inlet regulating valve for the sedimentation tank, a second slurry pump, a third slurry pump, a first surplus water pump, a second surplus water pump, and accessory slurry inlet pipes, water inlet pipes and surplus water drainage pipes, etc. The second slurry pump, the third slurry pump, the first surplus water pump, and the second surplus water pump are all frequency-regulated. There are water level detection, on-line monitoring of the conductivity of the supernatant liquid and on-line monitoring of the solid content of the slurry at the bottom of the sedimentation tank in the sedimentation tank, which are connected to the automatic control system platform. Through the upper and lower limits of the water level, the total amount control of the inlet and outlet media is realized. Through the upper and lower limits of the supernatant liquid, the regulation of the middle water inlet and the surplus water discharge is realized. Through the upper and lower limits of the solid content of the slurry at the bottom, the start-stop control and regulation of the third slurry pump are realized; the first surplus water pump is used to discharge the surplus supernatant liquid in the sedimentation tank to the alkali residue pulping tank for supplementary water for slag pond dredging and pulping; the second surplus water pump is used to discharge the supernatant liquid remaining after the sedimentation tank is used for supplementary water for slag pond dredging and pulping to the surplus water treatment device; preferably, the inlet of the third slurry pump can be set to multiple ones, evenly distributed at the bottom of the sedimentation tank, or set to be movable to realize the orderly transportation of the sedimented slurry at the bottom;

[0055] Filter pressing and turning system, realizing the removal of Cl -Press filtration dehydration and primary crushing of the post-alkali residue slurry, including a filter press, a turning and crushing machine, a tail water pump and auxiliary pipelines, etc. The tail water pump is connected to a tail water treatment device and is used to transport the tail water filtered out by the slurry pressing to the tail water treatment device; the turning and crushing machine is used to perform primary crushing on the dry slag filter cake generated after the alkali residue slurry is dehydrated by press filtration to form relatively fine particles, facilitating subsequent drying and pulverization; preferably, the turning and crushing machine can be set to be movable, and the dry slag particles after primary crushing can be laid flat on the factory site, and through sun drying and regular turning, the moisture content of the dry slag particles can be further reduced, thereby reducing the energy consumption of subsequent thermal drying;

[0056] Dry slag pulverization system, which realizes the pulverization of dry slag particles to produce alkali slag desulfurizer powder, including a belt conveyor, a hoist, a feed bin, a feeder, a pulverizer and related auxiliary facilities, etc. The belt conveyor and the feeder are both weighing type and are connected to an automatic control system platform, which can realize the monitoring and recording of relevant data of the incoming dry slag particles;

[0057] Powder selection and dust collection system, which realizes the separation of coarse and fine powders of the desulfurizer powder prepared by the pulverizer, and temporarily stores the qualified desulfurizer fine powder produced in the dust collector. The selected coarse powder is re-transported to the pulverizer through a return powder pipe for secondary grinding, including a powder separator and a dust collector. A speed controller is installed on the powder separator to adjust the rotation speed of the powder separator; an on-line particle size analysis unit is installed in the dust collector to perform on-line particle size analysis on the prepared desulfurizer fine powder finished product, and transmit the analysis result to the automatic control system platform. The platform is built-in with control logics such as a PID controller, and by adjusting the rotation speed of the powder separator, the particle size control of the produced fine powder is realized;

[0058] Flue gas and air system, which realizes the transportation and heat exchange of the system flue gas and air, including an induced draft fan 23, a flue gas and air heat exchanger, a chimney, a forced draft fan, a hot blast stove and auxiliary systems such as air ducts connecting them. The function of the induced draft fan is to draw out the clean flue gas dusted in the dust collector, and finally discharge it into the atmosphere through the chimney after heat exchange with cold air through the flue gas and air heat exchanger; the flue gas and air heat exchanger is used to realize the heat exchange between hot flue gas and cold air, recover the waste heat of the flue gas, and save the energy consumption of air heating. It can be rotary, tubular, plate type and heat pipe type; especially, when the flue gas and air heat exchanger is set as a heat pipe type, as Figure 3 shown, it is composed of a heat exchanger shell, gravity heat pipes, heat exchange fins, flue gas and air partitions, air ducts, flue ducts, ash hoppers, ash discharge valves and ash discharge pipes 2409; the hot blast stove is used to heat the hot air to the temperature required for drying the particles entering the pulverizer. On-line flue gas temperature measuring points are provided on the inlet and outlet flue ducts of the hot blast stove, and the load of the hot blast stove is controlled by setting the outlet flue gas temperature; preferably, the hot blast stove can be electric, or can be set as a form of heating with natural gas, biomass, biogas, coal or other renewable energy according to resource endowments.

[0059] The main function of the alkali slag slurry making system is to prepare the alkali slag accumulated in the alkali slag dam into alkali slag slurry that is easy to transport in liquid form through hydraulic flushing equipment. The slurry preparation process is as follows:

[0060] S11: The first residual water pump pumps the excess water in the supernatant of the sedimentation tank to the alkali residue pulping tank;

[0061] S12: forming a liquid slurry by mixing and crushing with a mobile alkali slag mixing and crushing device;

[0062] S13: The first slurry pump pumps the prepared slurry to the mixing tank.

[0063] Furthermore, the slurry inlet of the first slurry pump is provided with a filtering device so as to filter out impurities with larger particle sizes during the slurry suction process;

[0064] Furthermore, the mixing and crushing device is movable, such as a cutter suction boat type, a crawler type, etc.

[0065] The stirring reaction system is mainly used to mix and store alkali slag slurry with appropriate solid content concentration, and to mix the materials in the tank evenly and dissolve the soluble substances fully through stirring. The basic process flow is as follows:

[0066] S21: the slurry of the alkali slag slurry making system is transported to the stirring tank through the first slurry pump;

[0067] S22: Measure and read the monitoring value of the online solid content detection device;

[0068] S23: Control the opening of the water inlet regulating valve to adjust the solid content to the set value;

[0069] S24: adding salt-fixing agent;

[0070] S25: dispersant addition;

[0071] S26: Continue stirring until the required reaction time.

[0072] Preferably, the alkali slag slurry inlet of the stirring tank can be set to multiple, and flow into the stirring tank at different angles around the stirring tank to further promote the mixing of the slurry and save stirring energy.

[0073] The slurry sedimentation system is used to achieve the primary liquid-solid separation of alkali slag slurry by static method, including sedimentation tank, sedimentation tank water inlet regulating valve, second slurry pump, third slurry pump, first residual water pump, second residual water pump and auxiliary slurry inlet pipeline, water inlet pipeline and residual water drainage pipeline, etc. The main process is as follows:

[0074] S31: The second slurry pump pumps the stirred and mixed alkali slag slurry to the sedimentation tank and reaches a suitable liquid level;

[0075] S32: Standing, homogenizing, and precipitating;

[0076] S33: Online monitoring of the conductivity of the supernatant. By adjusting the opening of the inlet regulating valve of the sedimentation tank, the influent flow rate is adjusted to reduce the conductivity of the supernatant to the set value;

[0077] S34: The excess supernatant is pumped to the alkali residue pulping tank and the surplus water treatment facility through the first surplus water pump and the second surplus water pump;

[0078] S35: When the solid content rate of the bottom slurry rises to the set value, the third slurry pump is started until the solid content rate of the bottom slurry drops to the lowest lower limit value, and then the third slurry pump is closed.

[0079] Further, the second slurry pump, the third slurry pump, the first surplus water pump, and the second surplus water pump are all frequency conversion regulated.

[0080] Further, a water level detection, an online monitoring of the conductivity of the supernatant, and an online monitoring device for the solid content rate of the bottom slurry in the sedimentation tank are provided and connected to the automatic control system platform. Through the upper and lower limits of the water level, the total control of the inlet and outlet media is realized. Through the upper and lower limit values of the supernatant, the regulation of the influent of reclaimed water and the discharge of surplus water is realized. Through the upper and lower limit values of the solid content rate of the bottom slurry, the control and regulation of the start and stop of the third slurry pump are realized.

[0081] Further, the first surplus water pump is used to discharge the excess supernatant in the sedimentation tank to the alkali residue pulping tank for supplementary water for scouring and pulping in the slag pond.

[0082] Further, the second surplus water pump is used to discharge the supernatant remaining after the supplementary water for scouring and pulping in the slag pond in the sedimentation tank to the surplus water treatment device.

[0083] Preferably, the inlet of the third slurry pump can be provided with multiple ones, evenly distributed at the bottom of the sedimentation tank, or set to be movable, so as to realize the orderly transportation of the bottom sediment slurry.

[0084] The filter press and turning and throwing system is used to realize the filter press dehydration and primary crushing of the alkali residue slurry after removing Cl - including a filter press, a turning and throwing crusher, a tail water pump and auxiliary pipelines, etc. The main process is as follows:

[0085] S41: The third slurry pump pumps the slurry with an appropriate solid content rate to the filter press;

[0086] S42: The filter press filter-presses and dehydrates the slurry to form alkali residue blocks with an appropriate moisture content;

[0087] S43: The tail water filtered out is transported to the tail water treatment device by the tail water pump;

[0088] S44: The alkali residue blocks enter the turning and throwing crusher for primary crushing to form alkali residue particles;

[0089] S45: Spread the alkali residue particles out for drying in a flat layer and turn them over regularly.

[0090] S46: Reduce the water content of the alkali residue particles to the required value.

[0091] Preferably, the turning and crushing machine can be set as a movable type. The dry slag particles after primary crushing can be spread out on the factory site. Through drying and regular turning over, the water content of the dry slag particles can be further reduced, thereby reducing the energy consumption of subsequent thermal drying.

[0092] The dry slag crushing system is used to crush the dry slag particles to produce alkali residue desulfurizer powder, including a belt conveyor, a hoist, a feed bin, a feeder, a grinding mill and related auxiliary facilities, etc. The main process is as follows:

[0093] S51: The dried alkali residue particles are conveyed to the hoist by the belt conveyor.

[0094] S52: The hoist lifts the dry alkali residue particles to the feed bin.

[0095] S53: The dry alkali residue particles in the feed bin are sent to the grinding disc of the grinding mill through the feeder.

[0096] S54: The grinding mill grinds the dry slag machine particles into fine powder.

[0097] S55: The hot air introduced dries the fine powder and carries the fine powder to the powder separator.

[0098] Furthermore, the belt conveyor and the feeder are both weighing type and are connected to the automatic control system platform, which can realize the monitoring and recording of the relevant data of the incoming dry slag particles.

[0099] The powder separation and dust collection system is used to separate the coarse and fine powder of the desulfurizer powder prepared by the grinding mill, and temporarily store the qualified desulfurizer fine powder produced in the dust collector. The screened coarse powder is re-conveyed to the grinding mill through the return powder pipe for secondary grinding, including a powder separator and a dust collector. The main process is as follows:

[0100] S61: The dry slag powder crushed by the grinding mill is conveyed to the powder separator by hot air.

[0101] S62: The powder separator screens out the larger particle powder and conveys it to the grinding mill through the return powder pipe for secondary grinding.

[0102] S63: The qualified fine powder screened out by the powder separator is carried by the air flow to the dust collector.

[0103] S64: The dust collector traps the fine powder into the ash bin at the lower part of the dust collector.

[0104] S65: The clean flue gas after dust removal enters the inlet of the induced draft fan through the smoke exhaust port at the upper part of the dust collector and the flue connected thereto.

[0105] Further, a rotational speed controller is installed on the powder separator for adjusting the rotational speed of the powder separator; an on-line particle size analysis unit is installed in the dust collector for on-line particle size analysis of the finished desulfurizer fine powder prepared, and the analysis result is transmitted to the automatic control system platform. The platform is built-in with control logics such as a PID controller, and the particle size of the produced fine powder is controlled by adjusting the rotational speed of the powder separator.

[0106] Further, a level gauge and an ash discharge valve are provided at the bottom of the ash collection bin of the dust collector, which are connected to the centralized control platform and can automatically discharge ash according to the fine powder level.

[0107] Preferably, the fine powder discharged from the ash discharge valve can be directly transported by a tanker truck to the limestone desulfurizer powder bin of the power plant desulfurization system.

[0108] Preferably, the fine powder discharged from the ash discharge valve can also be transported to the temporary desulfurizer powder storage in the plant area by a bin pump.

[0109] Preferably, a bag filter can be added to the flue at the rear of the dust collector to perform secondary capture of the escaped alkali residue fine powder in the flue gas after dust collection.

[0110] The air and flue gas system is used to realize the transportation and heat exchange of the system flue gas and air, and includes an induced draft fan, an air and flue gas heat exchanger, a chimney, a forced draft fan, a hot blast stove and ancillary systems such as the flues connecting them. The main process is as follows:

[0111] S71: The clean flue gas after dust removal is sent to the air and flue gas heat exchanger by the induced draft fan;

[0112] S72: In the air and flue gas heat exchanger, the hot flue gas exchanges heat with the cold air;

[0113] S73: The flue gas after heat release is introduced into the chimney and discharged into the atmosphere;

[0114] S74: The air after heat absorption is sent into the hot blast stove by the forced draft fan;

[0115] S75: The air is reheated in the hot blast stove and heated to the temperature required for drying the particles entering the grinding mill;

[0116] S76: The hot air is sent into the grinding mill by the fan, dries the alkali residue powder in the grinding mill, and conveys the prepared powder out of the grinding mill.

[0117] Further, the air and flue gas heat exchanger is used to realize the heat exchange between the hot flue gas and the cold air, recover the waste heat of the flue gas, save the energy consumption for air heating, and can be a rotary type, a tubular type, a plate type and a heat pipe type;

[0118] In particular, when the fume-heat exchanger is of the heat pipe type, as Figure 3 shown;

[0119] Furthermore, the hot blast stove is used to heat hot air to the temperature required for drying the particles entering the pulverizer. Online flue gas temperature measuring points are provided on the inlet and outlet flue ducts of the hot blast stove, and the load of the hot blast stove is controlled by setting the outlet flue gas temperature.

[0120] Preferably, the hot blast stove can be electric, or can be set to burn natural gas, biomass, biogas, coal or other renewable energy heating forms according to resource endowments.

[0121] Furthermore, the system of the present utility model is provided with an automatic control platform, which collects data such as flue gas temperature, liquid level, valve opening, frequency converter frequency, flow rate, liquid conductivity, solid content of slurry, etc. in real time, and realizes the automatic control of the system through an automatic control program.

Claims

1. A device for preparing flue gas desulfurization agent using alkaline slag, characterized in that: The invention comprises an alkali slag pulping tank (1), a stirring tank (3), a sedimentation tank (5), and a filter press (7) which are sequentially connected via a slurry pump, a tumbling crusher (8) for processing solids in the filter press (7), a grinding mill (20), a powder selection machine (21), a dust collector (22), and an induced draft fan (23); a blower (26) is connected to the inside of the grinding mill (20) via a hot air furnace (27); and the blower (26) and the induced draft fan (23) are respectively connected to two heat exchange pipes of an air-smoke heat exchanger (24).

2. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: The stirring tank (3) and the sedimentation tank (5) are connected to the reclaimed water circulation pump (12) through the stirring tank water inlet regulating valve (13) and the sedimentation tank water inlet regulating valve (14) respectively.

3. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: The stirring tank (3) is connected to a dosing tank (15).

4. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: At least one residual water pump is connected to the bottom of the sedimentation tank (5), and one residual water pump is in communication with the alkali residue pulping tank (1).

5. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: The bottom of the filter press (7) is connected to a tailwater pump (18) for drainage.

6. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: A belt conveyor (9), an elevator (10) and a feeder (19) are sequentially arranged between the turning crusher (8) and the grinding mill (20); a feed bin (11) is arranged above the feeder (19); and the elevator (10) is connected to the feed bin (11).

7. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: The top of the grinding mill (20) is connected to the top of the powder concentrator (21), and the bottom of the powder concentrator (21) is connected to the middle of the grinding mill (20) to form a loop; the hot air furnace (27) is connected to both sides of the bottom of the grinding mill (20), so that convection is formed inside the grinding mill (20).

8. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: The air-smoke heat exchanger (24) comprises a heat exchanger shell (2401), wherein a gravity heat pipe (2402) and heat exchange fins (2403) are arranged in the heat exchanger shell (2401), and the heat exchanger shell (2401) is divided into two heat exchange pipes, an upper part being an air duct (2405) and a lower part being a smoke duct (2406); two ash hoppers (2407) are arranged at the bottom of the heat exchanger shell (2401), and an ash discharge pipe (2409) is arranged at the bottom of each ash hopper (2407), and an ash discharge valve (2408) is arranged on the ash discharge pipe (2409).

9. The device for preparing flue gas desulfurization agent using alkaline slag according to claim 1, characterized in that: In the air-smoke heat exchanger (24), the outlet end of the heat exchange pipe connected to the induced draft fan (23) is in communication with the chimney (25), and the inlet end of the heat exchange pipe connected to the blower (26) is in communication with the atmosphere.

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