A soda roaster capable of recovering waste heat and a soda co-production calcium carbonate process thereof

Abstract

The application provides a soda roaster capable of recovering waste heat and a soda co-production calcium carbonate process thereof, and relates to the technical field of waste heat recovery. The bottom is located at the right side of the roaster main body, the waste heat tank is installed on the upper surface of the bottom, the left and right sides of the waste heat tank are respectively sealed and installed with an air inlet frame and an air outlet frame, and the top of the roaster main body is sealed and installed with a flue gas pipe. The adjusting mechanism comprises a middle plate and a back plate, the middle plate is rotationally installed at the middle position in the air inlet frame, the back plate is fixedly arranged at the back of the middle plate, side plates are rotationally connected to the left and right sides of the middle plate in the air inlet frame, and a sealed installation pipe is installed on the outer wall of the waste heat tank. The scheme controls the angle adjustment of the middle plate and the side plates in the left-right direction, can force the flue gas concentrated in the middle to be guided to the two side areas, makes the flue gas fully contact in the whole heat exchange section, and fully activates the heat exchange area of the low-temperature area on the two sides.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste heat recovery, in particular to a soda calcination furnace capable of recovering waste heat and a soda co-production calcium carbonate process thereof. BACKGROUND

[0002] In the prior art, in the industrial process of calcining sodium bicarbonate to produce soda, the high-temperature calcination gas and fuel combustion flue gas discharged by the calcination furnace are directly discharged, which causes energy waste and cannot be well utilized. In addition, the flue gas flow field is very unstable during waste heat recovery, which easily affects the heat exchange effect.

[0003] Therefore, it is necessary to provide a soda calcination furnace capable of recovering waste heat and a soda co-production calcium carbonate process thereof to solve the above technical problems. SUMMARY

[0004] The present application provides a soda calcination furnace capable of recovering waste heat and a soda co-production calcium carbonate process thereof, which solves the problems that the waste heat of the calcination furnace cannot be well utilized during the soda calcination process, and the flue gas flow field distribution is unstable.

[0005] To solve the above technical problems, the present application provides a soda calcination furnace capable of recovering waste heat, which comprises a calcination furnace body, a base, a waste heat tank and an adjusting mechanism.

[0006] The base is located on the right side of the calcination furnace body, the waste heat tank is installed on the upper surface of the base, the left and right sides of the waste heat tank are respectively sealed and installed with an air inlet frame and an air outlet frame, and the top of the calcination furnace body is sealed and installed with a flue gas pipe.

[0007] The adjusting mechanism comprises a middle plate and a back plate, the middle plate is rotatably installed at the middle position inside the air inlet frame, the back plate is fixedly arranged on the back of the middle plate, the air inlet frame is rotatably connected with a side plate on both sides of the middle plate, the outer wall of the waste heat tank is installed with a sealing installation pipe, the sealing installation pipe is installed with an adjusting electric cylinder inside, the output end of the adjusting electric cylinder is installed with a push rod, the inner wall of the air inlet frame below the middle plate is fixedly arranged with a sliding rod, the outer wall of the sliding rod is slidably connected with a sliding frame, three limiting grooves are formed in the sliding frame, and the middle plate and the side plate are rotatably connected with guide wheels at the bottom.

[0008] The inside of the waste heat tank is installed with a heat exchange pipe, and the left and right ends of the heat exchange pipe are respectively integrally provided with an inlet pipe and an outlet pipe.

[0009] Preferably, the lengths of the middle plate and the side plate are consistent, and the middle plate and the side plate are consistent in spacing inside the air inlet frame.

[0010] Preferably, the push rod is slidably connected with the sealing installation pipe and the waste heat tank, and the output end of the push rod is fixedly installed with the side wall of the sliding frame.

[0011] Preferably, the guide wheel is embedded in the three limiting grooves, and the sliding frame can slide along the guide direction of the sliding rod.

[0012] Preferably, the heat exchange pipe is in a continuous "S" shape, the water inlet pipe and the water outlet pipe are respectively and sealingly installed with the waste heat box, and the outlet end of the flue gas pipe is connected with the outer wall of the air inlet frame.

[0013] Preferably, the device further comprises a flow guide mechanism.

[0014] The flow guide mechanism comprises a first flow guide plate and a second flow guide plate, both of which are rotatably installed in the waste heat box and located on both sides of the heat exchange pipe, the side wall of the first flow guide plate is fixedly provided with a first connecting plate, the bottom of the first connecting plate and located on one side of the first flow guide plate is rotatably connected with a first guide roller, the side wall of the second flow guide plate is fixedly provided with a second connecting plate, and the bottom of the second connecting plate and located on one side of the second flow guide plate is rotatably connected with a second guide roller.

[0015] Preferably, the device further comprises an auxiliary mechanism.

[0016] The top of the waste heat box is sealingly installed with a mounting cover through bolts, the auxiliary mechanism comprises a switching seat and a switching cylinder, the switching seat is installed on the top of the waste heat box and located in the mounting cover, the switching cylinder is installed on one side of the switching seat and located in the mounting cover, the left and right sides of the switching seat are respectively sealingly installed with an air outlet pipe, a liquid outlet pipe and an air inlet pipe, a liquid inlet pipe, a first through hole and a second through hole are respectively formed in the switching seat, a telescopic rod is installed on the output end of the switching cylinder and located in the switching seat, and a first block plug and a second block plug are respectively fixedly installed on the outer wall of the telescopic rod.

[0017] Preferably, the air outlet pipe and the liquid outlet pipe respectively extend into the waste heat box and are located above the heat exchange pipe, the lower surfaces of the air outlet pipe and the liquid outlet pipe are equidistantly installed with nozzles, the first through hole forms a communication between the air outlet pipe and the air inlet pipe, the second through hole forms a communication between the liquid outlet pipe and the liquid inlet pipe, and the outer walls of the first block plug and the second block plug are tightly fitted with the inner wall of the switching seat.

[0018] The process for co-production of soda ash and calcium carbonate comprises the following steps:

[0019] S1: mixing centrifugal salt and ammonium bicarbonate, the molar ratio of total sodium to total ammonium in the reaction system is 1:0.8-1.4, the double decomposition reaction is carried out at 30-50℃, the reaction time is 0.5-2h, and sodium bicarbonate and mother liquor I are obtained by filtering and washing; the obtained sodium bicarbonate is calcined to obtain soda ash, and the calcination needs to be carried out in the main body 1 of the calcining furnace;

[0020] S2: adding HCO3 −Ca(OH)2, HCO3 − The molar ratio of Ca(OH)2 to HCO3 is 1:0.5-0.8, the reaction time is 10-30 min, and after the reaction is completed, a first-stage causticizing residue, a causticizing mother liquor II and ammonia gas are generated; the first-stage causticizing residue obtained is directly wet-screened to obtain high-purity ultrafine calcium carbonate and a mixed product of calcium carbonate and calcium sulfate dihydrate, and the ammonia gas obtained is reused in S1.

[0021] S3: The pH of the mother liquor II obtained in S2 is adjusted to 8-9 by using sulfuric acid;

[0022] S4: SO4 is added to the mother liquor II obtained in S3; 2− Ca(OH)2, SO4 2− The molar ratio of Ca(OH)2 to SO4 is 1:1-1.5, the reaction time is 10-30 min, and after the reaction is completed, a second-stage causticizing residue, a causticizing mother liquor III and ammonia gas are generated; the second-stage causticizing residue obtained can form a calcium-based building material raw material with the mixed product in S2, and the ammonia gas obtained is reused in S1.

[0023] S5: The causticizing mother liquor III obtained in S4 is evaporated, the evaporation crystallization temperature is 70-130 DEG C, high-purity sodium sulfate and an evaporation mother liquor are obtained through filtration separation, and NH3 and H2O generated in the evaporation process can be reused in S1.

[0024] Compared with the related art, the soda roaster capable of recovering waste heat and the soda co-production calcium carbonate process thereof provided by the present application have the following beneficial effects:

[0025] The angle adjustment of the middle plate and the side plate in the left-right direction can force the flue gas concentrated in the middle to flow to the two side regions, so that the flue gas fully contacts in the whole heat exchange section, the heat exchange area of the low-temperature regions on the two sides is fully activated, the dust in the flue gas is prone to form "erosion" in the middle tube bundle when flowing at a high speed, and the dust is prone to deposit in the low-speed regions on the two sides, the flow of the flue gas to the two sides is guided by the middle plate and the side plate, the flow rate in the middle region is reduced, the erosion of the middle tube bundle is reduced, the flow rate in the two side regions is increased, the dust deposition is reduced by using air flow disturbance, the frequency of dust removal is reduced, and the service life of the heat exchange tube is effectively prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of the drawings shown.

[0027] Figure 1The best structural schematic diagram provided by the present application is shown in the figure;

[0028] Figure 2 The heat recovery tank cross-sectional structural schematic diagram is shown in the figure; Figure 1

[0029] Figure 3 The heat recovery tank cross-sectional structural schematic diagram is shown in the figure; Figure 1

[0030] Figure 4 The heat recovery tank and heat exchange pipe installation structural schematic diagram is shown in the figure; Figure 3

[0031] The adjustment mechanism structural schematic diagram is shown in the figure; Figure 5 Figure 3 The adjustment mechanism initial working state schematic diagram provided by the present application is shown in the figure;

[0032] Figure 6 The adjustment mechanism initial working state schematic diagram provided by the present application is shown in the figure;

[0033] Figure 7 The adjustment mechanism initial working state schematic diagram provided by the present application is shown in the figure; Figure 6

[0034] The adjustment mechanism initial working state schematic diagram provided by the present application is shown in the figure; Figure 8 Figure 6 The adjustment mechanism initial working state schematic diagram provided by the present application is shown in the figure;

[0035] Figure 9 The guide mechanism structural schematic diagram provided by the present application is shown in the figure;

[0036] Figure 10 The guide mechanism structural schematic diagram provided by the present application is shown in the figure; Figure 7

[0037] The guide mechanism structural schematic diagram provided by the present application is shown in the figure; Figure 11 Figure 8 The guide mechanism structural schematic diagram provided by the present application is shown in the figure;

[0038] Figure 12 The auxiliary mechanism structural schematic diagram provided by the present application is shown in the figure;

[0039] The auxiliary mechanism structural schematic diagram provided by the present application is shown in the figure; Figure 13 The A place enlarged structural schematic diagram shown in the figure; Figure 12

[0040] The auxiliary mechanism structural schematic diagram provided by the present application is shown in the figure; Figure 14 The soda ash co-production calcium carbonate process flow chart provided by the present application is shown in the figure.

[0041] Explanation of figure mark number:

[0042] 1, the main body of the calcination furnace, 2, the base; ​​​​

[0043] 3, waste heat box, 4, flue gas pipe;

[0044] 5, air inlet frame, 6, exhaust frame;

[0045] 7, adjusting mechanism, 71, middle plate, 72, side plate, 73, back plate, 74, adjusting electric cylinder, 75, push rod, 76, sliding rod, 77, sliding frame, 78, limiting groove, 79, guide wheel;

[0046] 8, flow guide mechanism, 81, first flow guide plate, 82, second flow guide plate, 83, first connecting plate, 84, first guide roller, 85, second connecting plate, 86, second guide roller;

[0047] 9, auxiliary mechanism, 91, switching seat, 92, air inlet pipe, 93, liquid inlet pipe, 94, air outlet pipe, 95, liquid outlet pipe, 96, nozzle, 97, switching electric cylinder, 98, telescopic rod, 99, first blocking plug, 910, second blocking plug, 911, first through hole, 912, second through hole;

[0048] 10, sealing installation pipe, 11, installation cover;

[0049] 12, heat exchange pipe, 13, water inlet pipe, 14, water outlet pipe. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0051] The present application provides a soda roaster capable of recovering waste heat and a soda co-production calcium carbonate process thereof.

[0052] First embodiment:

[0053] Please refer to Figures 1 to 8 A soda roaster capable of recovering waste heat, comprising a roaster main body 1, a base 2, a waste heat box 3 and an adjusting mechanism 7.

[0054] The base 2 is located on the right side of the roaster main body 1, the waste heat box 3 is installed on the upper surface of the base 2, air inlet frame 5 and exhaust frame 6 are respectively sealingly installed on the left and right sides of the waste heat box 3, and the flue gas pipe 4 is sealingly installed on the top of the roaster main body 1.

[0055] The adjusting mechanism 7 comprises a middle plate 71 and a back plate 73, the middle plate 71 is rotatably installed at the middle position inside the air inlet frame 5, the back plate 73 is fixedly installed at the back of the middle plate 71, the side plates 72 are rotatably connected on both sides of the middle plate 71 inside the air inlet frame 5, the sealing installation pipe 10 is installed on the outer wall of the waste heat box 3, the adjusting electric cylinder 74 is installed inside the sealing installation pipe 10, the push rod 75 is installed at the output end of the adjusting electric cylinder 74, the sliding rod 76 is fixedly installed on the inner wall of the air inlet frame 5 below the middle plate 71, the sliding frame 77 is slidably connected on the outer wall of the sliding rod 76, three limiting grooves 78 are arranged in the sliding frame 77, and the guide wheels 79 are rotatably connected to the bottom of the middle plate 71 and the side plates 72.

[0056] The waste heat box 3 is internally provided with the heat exchange pipe 12, and the water inlet pipe 13 and the water outlet pipe 14 are integrally arranged at the left and right ends of the heat exchange pipe 12.

[0057] Please refer to Figure 5 : the user starts the adjusting electric cylinder 74 to control the forward and backward movement of the push rod 75;

[0058] Please refer to 4 and Figure 6 : in the initial state, the orientation directions of the middle plate 71 and the side plates 72 about the air inlet frame 5 are consistent, and in this state, the high-temperature flue gas entering from the air inlet frame 5 will wash the heat exchange of the middle section position of the heat exchange pipe 12 through the gap between the middle plate 71 and the side plates 72;

[0059] Please refer to Figure 4 and Figure 7 : the user controls the adjusting electric cylinder 74 to control the push rod 75 to drive the sliding frame 77 to move forward, and in the movement process of the sliding frame 77, the guide wheels 79 in the three limiting grooves 78 are limited by force, at this time, the guide wheels 79 move in the limiting grooves 78 to control the middle plate 71 and the side plates 72 on both sides to form a turning motion to the right side, and at this time, the flue gas in the air inlet frame 5 is blocked and will wash the heat exchange of the side of the heat exchange pipe 12;

[0060] Please refer to Figure 4 and Figure 8 : if the user controls the adjusting electric cylinder 74 to control the push rod 75 to drive the sliding frame 77 to move backward, and in the movement process of the sliding frame 77, the guide wheels 79 in the three limiting grooves 78 are controlled by force to control the middle plate 71 and the side plates 72 on both sides to form a turning motion to the left side, and at this time, the flue gas in the air inlet frame 5 is blocked and will wash the heat exchange of the other side of the heat exchange pipe 12.

[0061] The lengths of the middle plate 71 and the side plates 72 are consistent, and the intervals of the middle plate 71 and the side plates 72 about the inside of the air inlet frame 5 are consistent.

[0062] The push rod 75 is in sliding connection with the sealing installation pipe 10 and the waste heat box 3, and the output end of the push rod 75 is fixedly installed with the side wall of the sliding frame 77.

[0063] The guide wheel 79 is embedded in the three limiting grooves 78, and the sliding frame 77 can slide along the guide direction of the slide rod 76.

[0064] The heat exchange pipe 12 is in a continuous "S" shape structure, the water inlet pipe 13 and the water outlet pipe 14 are respectively sealingly installed with the waste heat box 3, and the outlet end of the flue gas pipe 4 is connected with the outer wall of the air inlet frame 5.

[0065] It can be understood that: please refer to Figures 3 to 5 The sealing installation pipe 10 is sealingly installed on the entire adjusting electric cylinder 74, so that the working sealing property and stability of the adjusting electric cylinder 74 can be ensured, the stability of the sliding frame 77 in the sliding process is ensured by arranging the slide rod 76, and the service life of the guide wheel 79 can be improved by reducing the friction between the guide wheel 79 and the limiting groove 78 during the movement.

[0066] In this embodiment

[0067] Compared with the traditional air inlet frame 5, the flue gas is concentrated in the middle part of the heat exchange surface (the flow rate is too high), and the low-speed "dead zone" is formed on both sides due to the problems of the inlet structure or the arrangement of the pipe bundle;

[0068] By adjusting the angle of the middle plate 71 and the side plate 72 in the left-right direction, the flue gas concentrated in the middle part can be forced to flow to the two side regions, so that the flue gas can fully contact in the entire heat exchange section, the heat exchange area of the low-temperature region on both sides is fully activated, the dust in the flue gas is easy to form "erosion" in the middle pipe bundle when flowing at high speed, and the dust is easy to deposit in the low-speed region on both sides. By forming the flow guide by the middle plate 71 and the side plate 72, the flue gas is divided to the two sides, the flow rate in the middle region is reduced, the erosion of the middle pipe bundle is reduced, the flow rate in the two side regions is increased, the dust deposition is reduced by using the air flow disturbance, the frequency of dust removal is reduced, and the service life of the heat exchange pipe 12 is effectively improved.

[0069] Second embodiment:

[0070] Please refer to Figures 9 to 11 It also includes a flow guide mechanism 8.

[0071] The flow guide mechanism 8 comprises a first flow guide plate 81 and a second flow guide plate 82, both of which are rotatably installed inside the waste heat tank 3 and located on both sides of the heat exchange pipe 12, the side wall of the first flow guide plate 81 is fixedly provided with a first connecting plate 83, the bottom of the first connecting plate 83 and on one side of the first flow guide plate 81 is rotatably connected with a first guide roller 84, the side wall of the second flow guide plate 82 is fixedly provided with a second connecting plate 85, and the bottom of the second connecting plate 85 and on one side of the second flow guide plate 82 is rotatably connected with a second guide roller 86.

[0072] It can be understood that: please refer to Figure 9 , the first flow guide plate 81 and the second flow guide plate 82 are initially in an inclined state, so when the flue gas is concentrated in the middle segment position, the first flow guide plate 81 and the second flow guide plate 82 can also play a role in flow guiding.

[0073] Please refer to 10: when the side plate 72 moves to the right side, the side plate 72 will resist the force of the first guide roller 84 to control the first connecting plate 83 to control the first flow guide plate 81 to form a clockwise overturning to increase the inclined surface, so that the flue gas passing through the right side will be guided by the first flow guide plate 81;

[0074] Please refer to Figure 11 : when the side plate 72 moves to the left side, the side plate 72 will resist the force of the second guide roller 86 to control the second connecting plate 85 to control the second flow guide plate 82 to form a counterclockwise overturning to increase the inclined surface, so that the flue gas passing through the left side will be guided by the second flow guide plate 82;

[0075] Please refer to Figure 10 and Figure 11 : no matter whether the side plate 72 overturns to the left side or the right side, the middle plate 71 will synchronously overturn, when the middle plate 71 overturns to the left side, the back plate 73 will reduce the space on the right side of the air inlet frame 5, ensuring that a large amount of flue gas enters the left side, and when the middle plate 71 overturns to the right side, the back plate 73 will reduce the space on the left side of the air inlet frame 5, ensuring that a large amount of flue gas enters the right side.

[0076] In this embodiment

[0077] In the flow process of flue gas, the boundary layer is formed on the inner wall of the waste heat tank 3 due to the influence of the wall surface viscous force, the thermal resistance of low-speed flue gas in the boundary layer is extremely large, the heat exchange efficiency between the flue gas and the wall surface is extremely low, the first flow guide plate 81 and the second flow guide plate 82 arranged in an inclined manner can directly cut the low-speed boundary layer adhering to the wall, forcing the flue gas to change the flow direction from “parallel flow along the wall” to “oblique impact on the main flow area”, breaking the stable state of the low-speed layer, so that the high-temperature main flow flue gas can more directly contact the heat exchange pipe 12;

[0078] The wall-attached flue gas is stirred into the main high-temperature flue gas by the guide flow, the mixing of the cold and hot flue gas is promoted, the temperature stratification near the wall is eliminated, and the flue gas temperature distribution in the waste heat box 3 is more uniform. In addition, the inclination angle of the first guide plate 81 and the second guide plate 82 is determined according to the overturning angle of the side plate 72, so the greater the guide flue gas amount, the greater the inclination angle. In this way, the degree of flue gas stirring and reversing can be greater.

[0079] Third embodiment:

[0080] Please refer to Figure 3 、 Figures 12 to 13 , also includes an auxiliary mechanism 9;

[0081] The top of the waste heat box 3 is sealingly installed with a mounting cover 11 by bolts, the auxiliary mechanism 9 includes a switching seat 91 and a switching electric cylinder 97, the switching seat 91 is installed on the top of the waste heat box 3 and located inside the mounting cover 11, the switching electric cylinder 97 is installed on one side of the switching seat 91 and located inside the mounting cover 11, the left and right sides of the switching seat 91 are sealingly installed with an air outlet pipe 94, a liquid outlet pipe 95 and an air inlet pipe 92, a liquid inlet pipe 93 respectively, the inside of the switching seat 91 is throughly provided with a first through hole 911 and a second through hole 912 respectively, the output end of the switching electric cylinder 97 and located inside the switching seat 91 is installed with a telescopic rod 98, the outer wall of the telescopic rod 98 is fixedly provided with a first block plug 99 and a second block plug 910 respectively.

[0082] Please refer to Figure 12 and Figure 13 : In the initial state, the second block plug 910 blocks the first through hole 911, cutting off the air inlet pipe 92 and the air outlet pipe 94. At this time, the cleaning liquid entering through the liquid inlet pipe 93 will enter into the liquid outlet pipe 95 through the second through hole 912;

[0083] The user can start the switching electric cylinder 97 to control the telescopic rod 98 to drive the first block plug 99 and the second block plug 910 to move backward, then the first block plug 99 blocks the second through hole 912, cutting off the liquid inlet pipe 93 and the liquid outlet pipe 95. At this time, the gas entering into the switching seat 91 through the air inlet pipe 92 will be discharged through the air outlet pipe 94.

[0084] Please refer to Figure 3 and Figure 12 : Whether it is the air outlet pipe 94 or the liquid outlet pipe 95 will enter into the inside of the waste heat box 3, and be sprayed on the surface of the heat exchange pipe 12 by the fan-shaped spray head 96.

[0085] The gas outlet pipe 94 and the liquid outlet pipe 95 extend into the waste heat box 3 and are located above the heat exchange pipe 12, the lower surfaces of the gas outlet pipe 94 and the liquid outlet pipe 95 are equidistantly provided with spray heads 96, the first through hole 911 forms a communication between the gas outlet pipe 94 and the gas inlet pipe 92, the second through hole 912 forms a communication between the liquid outlet pipe 95 and the liquid inlet pipe 93, and the outer walls of the first and second blocking plugs 99 and 910 are tightly attached to the inner wall of the switching seat 91.

[0086] The present embodiment

[0087] Impurities (such as sodium salt crystals generated by calcination of sodium bicarbonate, unreacted raw material powder, dust, etc.) are usually carried in the waste heat flue gas, which gradually deposits on the surface of the heat exchange pipe 12 to form a dust layer or a scale layer, and in severe cases, the machine needs to be stopped for cleaning, interrupting the waste heat recovery process;

[0088] By providing the liquid outlet pipe 95, online or semi-online cleaning can be achieved (without completely stopping, only reducing the flue gas flow), the fan-shaped water flow can directly flush the dust and scale on the surface of the heat exchange pipe 12, and the cleaning effect of the gap dust of the "S"-shaped heat exchange pipe 12 is remarkable. After cleaning the liquid outlet pipe 95, water will remain on the surface of the heat exchange pipe 12, and the gas outlet pipe 94 can dry the heat exchange element by introducing dry compressed air (or preheated inert gas), which can eliminate "vapor resistance", avoid sudden increase of flow resistance, avoid vaporization vapor resistance, maintain the flow resistance in the normal range, and also avoid corrosion of the heat exchange pipe 12.

[0089] Fourth embodiment

[0090] Please refer to Figure 14 , soda ash co-production calcium carbonate process, comprising the following steps:

[0091] S1: mixing centrifugal salt and ammonium bicarbonate, the molar ratio of total sodium to total ammonium in the reaction system is 1:0.8-1.4, the double decomposition reaction is carried out at 30-50℃, the reaction time is 0.5-2h, and sodium bicarbonate and mother liquor I are obtained by filtering and washing; the obtained sodium bicarbonate is calcined to obtain soda ash, and the calcination is carried out in the main body 1 of the calcination furnace;

[0092] S2: adding HCO3 − Ca(OH)2 required for complete reaction, the molar ratio of HCO3 − to Ca(OH)2 in the causticization process is 1:0.5-0.8, the reaction time is 10-30min, and after the reaction is completed, a first causticization residue, a causticization mother liquor II and ammonia gas are generated; the obtained first causticization residue is directly wet screened to obtain high-purity ultrafine calcium carbonate and a mixed product of calcium carbonate and calcium sulfate dihydrate, and the obtained ammonia gas is recycled to S1;

[0093] S3: Adjust the pH of the mother liquor II obtained in S2 to 8-9 using sulfuric acid;

[0094] S4: Add SO4 to mother liquor II obtained in S3 2− The Ca(OH)2 required for complete reaction, and the SO4 during causticization process 2− The molar ratio of Ca(OH)2 to Ca is 1:1-1.5, the reaction time is 10-30 min, and after the reaction is completed, a second-stage causticizing slag, causticizing mother liquor III and ammonia are produced; the obtained second-stage causticizing slag can be mixed with the mixed products in S2 to form calcium-based building material raw materials, and the obtained ammonia is recycled to S1;

[0095] S5: The causticizing mother liquor III obtained from the evaporation of S4 has an evaporation crystallization temperature of 70-130℃. After filtration and separation, high-purity sodium sulfate and the evaporation mother liquor are obtained. The NH3 and H2O generated during the evaporation process can be reused in S1.

[0096] This embodiment: This invention introduces inexpensive and stable Ca(OH)2 and employs a novel two-stage causticization process to achieve efficient ammonia recycling in the alkali production process, successfully producing high-purity ultrafine calcium carbonate, solid sodium sulfate, and calcium-based building material raw materials. In the Ca(OH)2 two-stage causticization process, due to the high ammonia recycling rate of CaCO3 (2.80 × 10⁻⁶), the ammonia is recycled to form CaCO3. −9 ) and CaSO4·2H2O (3.14×10 −5 The solubility product constants of the two differ significantly at standard temperatures, therefore, staged causticization can be achieved by adjusting the amount of Ca(OH)2 added: Casticization stage I mainly involves HCO3- − The reaction yields a causticizing slag with a high CaCO3 content. Subsequent wet sieving yields high-purity ultrafine calcium carbonate and a mixed product of CaSO4·2H2O and CaCO3 (the particle size difference between calcium carbonate and calcium sulfate dihydrate is significant). Causticizing stage II mainly involves SO4... 2− The reaction occurs, but the added Ca(OH)2 cannot react completely. Therefore, the second-stage causticizing slag mainly consists of CaSO4·2H2O, Ca(OH)2, and a small amount of CaCO3, which can be used as a calcium-based raw material for building materials. The causticizing filtrate mainly consists of sodium sulfate and ammonia water, which can be processed by evaporation and crystallization to obtain high-purity sodium sulfate solid. In addition, there are three ammonia production steps in the process, which can remove NH4+ from the solution. + All of it is converted into NH3, achieving efficient recovery and utilization of ammonia at the front end of the ammonia-soda process for producing soda ash.

[0097] Please refer to the reference again. Figures 1 to 1 4. The working principle of the soda ash roasting furnace with waste heat recovery and the soda ash co-production calcium carbonate process provided by the present invention is as follows:

[0098] Step S1, in the fourth embodiment, the obtained bicarbonate is placed in the calcination furnace main body 1 to obtain soda ash, and high-temperature flue gas is discharged from the flue gas pipe 4 during calcination. Users need to match an external bag dust collector to filter and process large particles, only leaving high-temperature flue gas into the air inlet frame 5, and then through the heat exchange pipe 12 in the air inlet frame 5 and the waste heat tank 3 to form waste heat recovery heat exchange. Users pass cold water into the heat exchange pipe 12 through the water inlet pipe 13, and finally the heat heats the cold water in the heat exchange pipe 12, which is discharged through the water outlet pipe 14. The steam formed during the heat exchange process can be used for soda ash drying;

[0099] Step S2, air inlet frame 5 adjustment;

[0100] The user controls the adjusting electric cylinder 74 to control the push rod 75 to drive the sliding frame 77 to move forward. In the process of moving the sliding frame 77, the three limiting grooves 78 are stressed, and the corresponding guide wheels 79 in the limiting grooves 78 are moved, thereby affecting the control of the middle plate 71 and the side plates 72 on both sides to form a turning motion to the right. At this time, the flue gas in the air inlet frame 5 is blocked and will wash the heat exchange of the side of the heat exchange pipe 12.

[0101] The user controls the adjusting electric cylinder 74 to control the push rod 75 to drive the sliding frame 77 to move backward. In the process of moving the sliding frame 77, the three limiting grooves 78 are stressed, and the guide wheels 79 control the middle plate 71 and the side plates 72 on both sides to form a turning motion to the left. At this time, the flue gas in the air inlet frame 5 is blocked and will wash the heat exchange of the other side of the heat exchange pipe 12.

[0102] Step S3, cleaning the heat exchange pipe 12 after heat exchange;

[0103] The cleaning liquid entering through the liquid inlet pipe 93 will enter the liquid outlet pipe 95 through the second through hole 912 and be sprayed on the surface of the heat exchange pipe 12 through the fan-shaped spray head 96;

[0104] After a period of spraying, the switching cylinder 97 is started to control the extension rod 98 to drive the first block plug 99 and the second block plug 910 to move backward, so that the first block plug 99 blocks the second through hole 912, cutting off the liquid inlet pipe 93 and the liquid outlet pipe 95. At this time, the gas entering the switching seat 91 through the air inlet pipe 92 will be discharged through the air outlet pipe 94, and the gas will be sprayed on the surface of the heat exchange pipe 12 through the fan-shaped spray head 96.

[0105] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made in the concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A sodium carbonate calcining furnace capable of recovering waste heat, characterized by, It comprises a roasting furnace body, a base, a waste heat tank and an adjusting mechanism. The base is located at the right side of the roasting furnace body, the waste heat tank is installed on the upper surface of the base, the left and right sides of the waste heat tank are respectively sealedly installed with an air inlet frame and an air outlet frame, and the top of the roasting furnace body is sealedly installed with a flue gas pipe. The adjusting mechanism comprises a middle plate and a back plate, the middle plate is rotationally installed at the middle position inside the air inlet frame, the back plate is fixedly arranged at the back of the middle plate, the left and right sides of the middle plate inside the air inlet frame are rotationally connected with side plates, a sealing installation pipe is installed on the outer wall of the waste heat tank, an adjusting electric cylinder is installed inside the sealing installation pipe, a push rod is installed at the output end of the adjusting electric cylinder, a sliding rod is fixedly arranged on the inner wall of the air inlet frame below the middle plate, a sliding frame is slidingly connected with the outer wall of the sliding rod, three limiting grooves are formed in the inner part of the sliding frame, and guide wheels are rotationally connected with the bottom of the middle plate and the side plate respectively. The waste heat tank is internally installed with heat exchange pipes, and the left and right ends of the heat exchange pipes are respectively integrally provided with water inlet pipes and water outlet pipes. The length of the middle plate and the side plate is consistent, and the interval of the middle plate and the side plate inside the air inlet frame is consistent. The push rod is slidingly connected with the sealing installation pipe and the waste heat tank, and the output end of the push rod is fixedly installed with the side wall of the sliding frame. The guide wheels are embedded in the three limiting grooves, and the sliding frame can slide along the guide direction of the sliding rod. It further comprises a flow guide mechanism. The flow guide mechanism comprises first and second flow guide plates, the first and second flow guide plates are rotationally installed inside the waste heat tank and located at the left and right sides of the heat exchange pipes through torsional springs, a first connecting plate is fixedly arranged on the side wall of the first flow guide plate, a first guide roller is rotationally connected with the bottom of the first connecting plate and located at one side of the first flow guide plate, a second connecting plate is fixedly arranged on the side wall of the second flow guide plate, and a second guide roller is rotationally connected with the bottom of the second connecting plate and located at one side of the second flow guide plate. It further comprises an auxiliary mechanism. The top of the waste heat tank is sealedly installed with a mounting cover through bolts, the auxiliary mechanism comprises a switching seat and a switching electric cylinder, the switching seat is installed at the top of the waste heat tank and located inside the mounting cover, the switching electric cylinder is installed at one side of the switching seat and located inside the mounting cover, the left and right sides of the switching seat are respectively sealedly installed with an air outlet pipe and a liquid outlet pipe and an air inlet pipe and a liquid inlet pipe, a first through hole and a second through hole are respectively formed in the inner part of the switching seat, a telescopic rod is installed at the output end of the switching electric cylinder and located inside the switching seat, and a first blocking plug and a second blocking plug are respectively fixedly arranged on the outer wall of the telescopic rod.

2. The sodium carbonate calcining furnace with recoverable waste heat according to claim 1, characterized in that, The heat exchange pipes are in a continuous "S" shape structure, the water inlet pipes and the water outlet pipes are respectively sealedly installed with the waste heat tank, and the outlet end of the flue gas pipe is communicated with the outer wall of the air inlet frame.

3. The sodium carbonate calcining furnace with recoverable waste heat according to claim 1, characterized in that, The air outlet pipe and the liquid outlet pipe respectively extend to the inside of the waste heat tank and are located above the heat exchange pipes, the lower surfaces of the air outlet pipe and the liquid outlet pipe are equidistantly installed with spray heads, the first through hole forms communication between the air outlet pipe and the air inlet pipe, the second through hole forms communication between the liquid outlet pipe and the liquid inlet pipe, and the outer walls of the first blocking plug and the second blocking plug are tightly fitted with the inner wall of the switching seat.

4. A process for the co-production of soda ash and calcium carbonate, characterised in that, The soda and calcium carbonate co-production process comprises the waste heat recoverable soda roasting furnace according to any one of claims 1-3, and comprises the following steps: S1: centrifugal mixing of salt and ammonium bicarbonate, the molar ratio of total sodium to total ammonium in the reaction system is 1:0.8-1.4, the double decomposition reaction is carried out at 30-50℃, the reaction time is 0.5-2h, filtration and washing to obtain sodium bicarbonate and mother liquor I; the obtained sodium bicarbonate is calcined to obtain pure soda, and the calcination needs to be carried out in the main body of the calcination furnace; S2: adding Ca(OH)2 required for complete reaction of HCO3-in the mother liquor I obtained in S1, the molar ratio of HCO3-to Ca(OH)2 in the causticization process is 1:0.5-0.8, the reaction time is 10-30min, after the reaction is completed, a section of causticizing residue, causticizing mother liquor II and ammonia gas are generated; the obtained first-stage causticizing residue is directly wet-screened to obtain high-purity ultrafine calcium carbonate and mixed products of calcium sulfate dihydrate and calcium carbonate, and the obtained ammonia gas is recycled to S1; S3: adjusting the pH of the mother liquor II obtained in S2 to 8-9 with sulfuric acid; S4: adding SO4 to mother liquor II obtained in S3 2 - Ca(OH)2 required for complete reaction, SO4 2 - the molar ratio of Ca(OH)2 to SO4 is 1:1-1.5, the reaction time is 10-30 min, and after the reaction is completed, a second-stage causticizing residue, a causticizing mother liquor III, and ammonia gas are produced; the second-stage causticizing residue can form a calcium-based building material raw material with the mixed product in S2, and the ammonia gas is recycled to S1; S5: evaporating the causticizing mother liquor III obtained in S4, the evaporation crystallization temperature is 70-130℃, high-purity sodium sulfate and evaporation mother liquor are obtained by filtration separation, and NH3 and H2O generated in the evaporation process can be recycled to S1.

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