Calcium formate drying device, calcium formate production device and working method thereof

Abstract

This invention discloses a calcium formate drying device, a calcium formate production device, and their operating method, belonging to the field of calcium formate production technology. The calcium formate drying device includes a hot air duct and a normal temperature air duct, both equipped with cyclone separators. A screening device is connected to the outlet of the first cyclone separator, and the screening device is connected to the normal temperature air duct. The calcium formate production device includes a reaction system, a transfer tank, a centrifuge, a mother liquor system, a drying system, and a hot air system. The operating method of the calcium formate production device includes feeding calcium carbonate powder and formic acid into each reaction vessel for mixing and reaction; the reacted material is temporarily stored in the transfer tank, then pumped into the centrifuge for solid-liquid separation; the separated solid calcium formate is dried by the drying system; the separated mother liquor, after impurity removal, is partially reused in the reaction vessel, and the remainder is evaporated in an evaporation vessel. This invention features continuous production, thorough impurity removal, and good energy-saving effects.

Description

Technical Field

[0001] This invention relates to the field of calcium formate production technology, specifically to a calcium formate drying device, a calcium formate production device, and its working method. Background Technology

[0002] The main method for producing calcium formate is to react formic acid solution with calcium carbonate to produce calcium formate product solution. After filtration to remove insoluble matter from the product solution, the filtrate is concentrated, crystallized, centrifuged, and dried to obtain calcium formate product.

[0003] Patent CN217900427U discloses a flash dryer for calcium formate production, comprising an air inlet device, a separator, and a cylindrical dryer shell. The dryer shell has a feed inlet on its side wall and a discharge outlet at its top, which is connected to the separator. The dryer is characterized by further including an air distributor, which comprises an annular air inlet pipe disposed on the bottom side wall of the dryer shell. The annular air inlet pipe has several air outlets that can form a spiral upward airflow within the dryer shell. An air inlet connected to the air inlet device is located on the outer circumferential wall of the annular air inlet pipe.

[0004] Patent CN114396763A discloses a drying equipment and its usage method for calcium formate production, including a base, a drying device, a grading and recovery device, and a crushing device. This drying equipment for calcium formate production utilizes a special flow channel formed by the main drying cylinder, the shielding guide hopper, the baffle cylinder, and the outer drying cylinder. This allows the wet material to be impacted and crushed from multiple directions under the influence of hot airflow, while simultaneously allowing for better contact between the airflow and the particles for drying. Furthermore, with the assistance of a second hot air blower, there is no problem of material falling and clogging. The mechanical size is significantly reduced, facilitating installation. The second hot air blower delivers hot airflow to one end of the discharge slope of the connecting pipe. Under the action of air pressure, the hot air carrying the particles in the outer drying cylinder is rapidly transported through the connecting pipe to the separation chamber, simultaneously providing secondary heating to the particles. The falling wet material is dispersed by impacting the inner wall of the main drying cylinder after being rotated by the movable fan.

[0005] Patent CN118623580A discloses a drying device for calcium formate production. The technical solution includes a shell, a bottom shell, a cover plate, and a dispersion assembly. A water tank is provided inside the shell, and a heat-conducting ring is fixedly installed on the inner wall of the shell, with one side of the heat-conducting ring extending into the water tank. A cover plate is bolted to the top of the shell, and a vacuum pump is fixedly installed on one side of the top of the cover plate. A gas scrubber is fixedly installed on the top of the vacuum pump. The bottom shell is fixedly installed at the bottom of the shell. This invention lowers the boiling point of the water inside the shell by reducing the air pressure, thereby promoting the evaporation of moisture inside the calcium formate powder in a low-temperature environment. While ensuring that the calcium formate powder is not affected by high temperatures, the device ensures the drying effect of the calcium formate powder, effectively preventing the calcium formate powder from undergoing qualitative changes under high temperatures, and thus reducing cost losses during the calcium formate drying process.

[0006] Traditional drying equipment has several shortcomings in the drying and impurity removal process of calcium formate products: such as short gas-solid contact time and limited contact area, resulting in insufficient drying of the material and difficulty in meeting the moisture content requirements for fine powder products; the waste heat generated during the drying process is not effectively recovered and utilized, resulting in high energy consumption and high production costs; and calcium formate crystals easily clog the drying tank during the drying process, making it difficult to clean.

[0007] Traditional calcium formate production equipment is a batch reaction. Formic acid solution and calcium carbonate are slowly added to the reactor according to the reaction ratio, and mixed with the added mother liquor by stirring to ensure a complete reaction. Feeding is stopped after the appropriate liquid level is reached according to the reactor volume. The reactants continue to react in the reactor for approximately 2.5 hours. After the reaction liquid composition meets the standards, the product solution is pumped to a scraper centrifuge. After centrifugation, the material is conveyed to a dryer, and the dried finished product is conveyed to a silo by a scraper conveyor, packaged according to specifications, and sold.

[0008] The aforementioned traditional calcium formate production equipment has the following problems: First, in traditional equipment, there are time intervals between feeding, reaction, and discharge in the production process, which means that the reaction process cannot be carried out continuously. From the start of feeding the material into the reactor to the cessation of the reaction, the total time to complete one reactor reaction is about 4 hours. This long time consumption leads to low equipment output, resulting in low output and high energy consumption.

[0009] Secondly, the water-insoluble content of calcium formate is a core indicator for calcium formate products. Incomplete removal of impurities affects the whiteness of the product, hindering market development. Water-insoluble matter mainly originates from impurities in the calcium carbonate raw material. These impurities accumulate in the reactor along with the calcium carbonate, resulting in poor crystallization and small crystal size. In traditional equipment, to reduce the water-insoluble content, the product solution needs to be allowed to settle in the reactor for about 0.5 hours to remove the upper layer of water-insoluble matter and impurities. This disrupts the continuous reaction process, is time-consuming, and the discharge of water-insoluble matter and impurities can easily lead to the loss of calcium formate product, resulting in significant material waste. Furthermore, when restarting the stirring device after the product solution has settled in the reactor, impurity deposits often cause difficulty in starting the device, potentially leading to motor burnout. Summary of the Invention

[0010] One of the objectives of this invention is to provide a calcium formate drying device, which has the characteristics of good drying effect and easy cleaning.

[0011] One of the objectives of this invention is to provide a calcium formate crystallization production line and its operating method, which features continuous production, thorough impurity treatment, and good energy-saving effect.

[0012] The technical solution adopted in this invention is as follows.

[0013] A calcium formate drying device includes a hot air duct and a normal temperature air duct. A first vertical pipe is movably connected to the bottom of the hot air duct. A first feed inlet is located on the side of the first vertical pipe, and the first feed inlet is connected to the outlet of a centrifuge used for solid-liquid separation of calcium formate liquid via a first feeder. The hot air duct, a horizontal pipe, and an absorption tower are connected in sequence. A first cyclone separator is connected to the hot air duct, and a screening device is connected to the outlet of the first cyclone separator. A second vertical pipe is connected to the bottom of the normal temperature air duct. A second feed inlet is located on one side of the bottom of the second vertical pipe, and the second feed inlet is connected to the outlet of the screening device via a second feeder. The top of the normal temperature air duct is connected to the absorption tower. A second cyclone separator is located on the normal temperature air duct. A first air inlet connected to the hot air device is located on the bottom surface of the first vertical pipe. A second air inlet is located on the bottom surface of the second vertical pipe. Exhaust fans are installed at the ends of the horizontal pipe and the normal temperature air duct near the absorption tower. Since the first riser has the highest volumetric heat transfer coefficient in the drying unit, it is most prone to crystallization adhering to its inner wall. This reduces the effective inner diameter of the first riser and makes online cleaning difficult. Therefore, a movable connection between the first riser and the first connecting pipe is adopted, allowing the first riser to be removed for cleaning or quick replacement at any time. The horizontal pipe design prevents condensate from flowing back into the first cyclone separator after drying, which could interfere with gas-solid mixing and reduce drying efficiency. The screened material undergoes a second drying process, resulting in better drying and facilitating particle size reduction and particle size distribution.

[0014] As a preferred technical solution, the diameter of the first riser is larger than the diameter of the hot air duct; the length of the first riser is not less than 2.5m.

[0015] The hot air duct is thinner than the first riser, facilitating pressurized conveying and ensuring that the wet material is fully heated and its moisture evaporates in the shortest possible time. Since the material first comes into contact with the high-temperature, high-speed airflow within the first riser, its upward velocity is zero upon entry, resulting in the highest particle density, the greatest relative velocity between gas and particles, and the highest volumetric heat transfer coefficient. The first riser, being thicker than the hot air duct, increases the contact time and area between the material and the hot air, allowing for thorough mixing and dispersion of the material before it enters the first hot air duct, resulting in excellent drying. The first riser is at least 2.5m long, covering the area most prone to crystallization.

[0016] As a preferred technical solution, the bottom surface of the first riser is an arc surface, and the arc surface is tangent to the bottom surface of the first feeder and the end of the inner wall of the first riser away from the first feeder.

[0017] The bottom surface of the first riser is designed with an arc-shaped structure. This arc-shaped structure guides the incoming hot air to form a spiral upward airflow, avoiding the formation of vortices or dead corners at the bottom of the riser. This allows the solid material fed in by the first conveyor to be quickly entrained by the hot air and evenly dispersed, improving the gas-solid contact efficiency in the initial drying stage. The arc-shaped structure can also reduce the accumulation of material at the bottom of the riser, preventing overheating, agglomeration, or crystallization caused by localized material aggregation.

[0018] As a preferred technical solution, the diameter of the second riser is larger than the diameter of the normal temperature air duct; the bottom surface of the second riser is an arc surface, which is tangent to the bottom surface of the second feeder and the end of the inner wall of the second riser away from the second feeder; the second air inlet is connected to the filter through the second connecting pipe.

[0019] The bottom surface of the second riser is designed with an arc surface structure. This arc surface structure guides the incoming hot air to form a spiral upward airflow, avoiding the formation of vortices or dead corners in the airflow at the bottom of the riser. This allows the solid material fed in by the second conveyor to be quickly entrained by the hot air and evenly dispersed, improving the gas-solid contact efficiency in the initial drying stage. The arc surface structure can also reduce the retention and accumulation of material at the bottom of the riser, preventing overheating, agglomeration, or crystallization caused by localized material accumulation.

[0020] As a preferred technical solution, the first cyclone separator and the second cyclone separator have the same structure, both including a first-stage cyclone separator and a second-stage cyclone separator connected in series.

[0021] Using this technical solution, the cyclone separator is mostly designed with dual separators, which has a high capture efficiency for fine particles and can solve the problem of some calcium formate fine powder being lost with the exhaust gas, reducing the product yield.

[0022] The calcium formate production apparatus includes a reaction system, a transfer tank, a centrifuge, a mother liquor system, a hot air system, and any one of the above-mentioned drying devices.

[0023] The reaction system includes several reaction groups, each reaction group including a reaction vessel and at least two insulated stirring vessels connected to the reaction vessel; each insulated stirring vessel is connected in sequence to a transfer tank and a centrifuge; each reaction vessel is connected to a powder silo for holding calcium carbonate powder and a formic acid tank; each reaction vessel and insulated stirring vessel is equipped with a stirrer.

[0024] The mother liquor system includes a filter, a sedimentation tank, and a temporary storage tank. The top pipe of the sedimentation tank side wall is equipped with an overflow port connected to the evaporator via a pipeline, and the bottom end of the sedimentation tank side wall is equipped with a waste liquid port connected to the evaporator via a pipeline. The bottom end of the sedimentation tank is equipped with a slag discharge door. The middle part of the sedimentation tank side wall is equipped with a supernatant port connected to the temporary storage tank via a pipeline. The centrifuge outlet, filter, and top of the sedimentation tank are connected in sequence via pipelines. The top of each reactor is equipped with an overflow hole connected to the evaporator via a pipeline. The top of the reactor is connected to the temporary storage tank via a pipeline.

[0025] The hot air system includes a first coil located on the outer periphery of the horizontal pipe and a hot air furnace. One end of the first coil is connected to a gas distribution valve, and the other end is open. The gas distribution valve is connected to a temporary storage tank and each reaction vessel through heat pipes.

[0026] The evaporator is equipped with a second coil, and the hot air furnace is connected in series with the second coil and the bottom of the first vertical pipe. The evaporator is connected to the absorption tower.

[0027] The tops of each reactor and evaporator are connected to the absorption tower via exhaust pipes.

[0028] Its beneficial effects are as follows: calcium carbonate powder and formic acid first undergo a preliminary reaction in a reactor, and light impurities are separated by overflow. Then, the mixture enters a heated and stirred reactor for further reaction, improving the reaction conversion rate and product purity, and reducing the pressure of subsequent impurity treatment. Each reactor corresponds to at least two heated and stirred reactors, eliminating the time intervals between feeding, reaction, and discharge in traditional batch production, and avoiding the problems of long reaction times and discontinuous operation in a single reactor. The production process is constantly stirred, with no sedimentation or waiting, avoiding the difficulty in starting the stirring device and the risk of motor burnout caused by impurity deposition. The mother liquor system achieves the recovery and utilization of effective components in the mother liquor through filtration, sedimentation, temporary storage, and linkage with the evaporation reactor, reducing raw material loss. When the material reaches the horizontal pipe, the material has already been dried. The first coil absorbs the heat from the horizontal pipe and supplies heat to the temporary storage tank and each reactor through the gas distribution valve for production, which is relatively energy-efficient. The horizontal setting of the horizontal pipe can prevent the condensate in the dried gas from easily flowing back into the first cyclone separator. Impurities and waste liquids are sorted and treated to reduce environmental pollution; the drying system is connected in series with the hot air furnace and evaporator, and the hot air first heats the evaporator before being used to dry the material, realizing the cascade utilization of thermal energy. In conjunction with the energy recovery system, the heat of the waste gas is recovered and used to heat the temporary storage tank and reaction vessel, improving energy utilization efficiency and reducing production energy consumption; the drying and cooling processes are combined, with two cyclone separation and screening devices to ensure the particle size of the finished product; the steam from the evaporator and the drying waste gas enter the absorption tower together for purification and discharge, reducing pollutant emissions.

[0029] As a preferred technical solution, each pipeline is equipped with a liquid pump.

[0030] As a preferred technical solution, a third coil is provided on the outer peripheral surface of the temporary storage tank, and a fourth coil is provided on the outer peripheral surface of each reactor. The air inlet end of each third coil and the air inlet end of each fourth coil are respectively connected to the gas distribution valve through a heat pipe. The air outlet end of each third coil and the air outlet end of each fourth coil are open. A first air pump is provided on each heat pipe. The first coil is connected to the gas distribution valve through a connecting pipe, and a second air pump is provided on the connecting pipe. The first air inlet is connected to the second coil through the first connecting pipe. An induced draft pump is provided on the first connecting pipe.

[0031] As a preferred technical solution, the bottom of the powder silo is connected to the distribution silo via a first screw feeder, and the distribution silo is connected to a weighing silo via two second screw feeders; each weighing silo is connected to a transfer silo via a third screw feeder; each reactor is connected to the transfer silo via a fourth screw feeder; the transfer silo is located above each reactor; each reactor is connected to a formic acid tank via a formic acid pipe; a formic acid pump is installed on the formic acid pipe, and the formic acid tank is located above each reactor.

[0032] The operating method of any of the above-mentioned calcium formate production devices is characterized by comprising the following steps: Step 1: Send the calcium carbonate powder from the powder silo and the formic acid from the formic acid tank into each reactor for mixing and reaction; when the liquid level in the reactor exceeds the height of the overflow hole, introduce the liquid rich in light impurities on the surface of the mixed reaction liquid into the evaporator through the top overflow hole.

[0033] Step 2: The mixed reaction materials are fed into a heated stirred tank in the same group and stirred continuously to complete the deep reaction; the reacted materials are transported to a transfer tank for temporary storage, and then pumped into a centrifuge for solid-liquid separation.

[0034] Step 3: The solid material separated by the centrifuge is discharged from the outlet, and the mother liquor is sent to the filter through the outlet to filter insoluble impurities. The filtered mother liquor enters the sedimentation tank for settling. The liquid containing floating impurities in the upper layer of the sedimentation tank enters the evaporation kettle through the overflow port of the top pipe on the side wall, and the waste liquid rich in insoluble impurities at the bottom flows into the evaporation kettle through the fourth pipeline. The supernatant is drawn out through the supernatant port and sent to the temporary storage tank. The sludge is discharged from the bottom of the sedimentation tank by opening the sludge discharge door at the periodic interval.

[0035] Step 4: The solid material discharged from the centrifuge enters the first vertical pipe through the first feeder. The hot air generated by the hot air furnace first flows through the second coil around the evaporator to heat it, and then enters the interior of the first vertical pipe from the bottom end to mix with the material. The dried material enters the first cyclone separator with the airflow, and the separated material is sent to the screening device for grading.

[0036] Step 5: The qualified material after screening enters the second vertical pipe through the second feeder, and cold air is introduced into the second vertical pipe to dry the material; the material is separated by the second cyclone separator to obtain calcium formate product.

[0037] Step 6: Cold air is introduced into the first coil around the outer periphery of the horizontal pipe to recover the heat of the waste gas in the pipe and form a hot air flow. The hot air flow is transferred through the gas distribution valve and heat pipe to the temporary storage tank and the reaction vessel for heating. The steam generated by the evaporation vessel and the waste gas of the drying system enter the absorption tower for purification before being discharged. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a preferred embodiment of the calcium formate production apparatus of the present invention.

[0039] Figure 2 yes Figure 1 A magnified view of part A.

[0040] Figure 3 yes Figure 1 A magnified view of part B.

[0041] Figure 4 yes Figure 1 A magnified view of part C.

[0042] Figure 5 yes Figure 1 A magnified view of part D.

[0043] Figure 6 yes Figure 1 A magnified view of part E.

[0044] Figure 7 yes Figure 1 A magnified view of part F.

[0045] Figure 8 yes Figure 1 A magnified view of part G.

[0046] Figure 9 yes Figure 8 A magnified view of part H.

[0047] Figure 10 yes Figure 8 A magnified view of part I.

[0048] Among them: reaction vessel-1; heat-insulated stirring vessel-11; powder silo-12; formic acid tank-13; formic acid pipe-131; formic acid pump-132; Overflow hole-14; First agitator-15; First screw feeder-16; Distribution bin-17; Second screw feeder-18; Weighing bin-19; Third screw feeder-110; Transfer bin-111; Fourth screw feeder-112; First exhaust pipe-113; Fourth coil-114; Transfer tank-2; Centrifuge-3; Evaporation kettle-4; Filter-41; Sedimentation tank-42; Overflow port-421; Waste liquid port-422; Supernatant port-423; Slag discharge door-424; Temporary storage tank-43; Third coil-431; Second coil-44; Filter device-45; Twelfth pipeline-46; Hot air duct-5; Normal temperature air duct-51; First riser-52; First air inlet-521; First connecting pipe-522; Exhaust pump-523; Bottom surface of first riser-524; Second riser bottom surface - 581; First feeder - 53; First feed inlet - 54; Horizontal pipe - 55; First cyclone separator - 56; First primary cyclone separator - 561; First secondary cyclone separator - 562; Screening device - 57; Second riser - 58; Bottom surface of second riser - 581; Second air inlet - 582; Second connecting pipe - 583; Filter - 584; Second cyclone separator - 59; Second primary cyclone separator - 591; Second secondary cyclone separator - 592; Finished product collection device - 593; Second feeder - 510; Second feed inlet - 511; First connector - 512; Second connector - 513; Hot air furnace-6; First coil-61; Gas distribution valve-62; Connecting pipe-621; Second air pump-622; Heat pipe-63; First air pump-631; Absorber tower-7; First induced draft fan-71; Second induced draft fan-72; Pipeline 1-81; Pipeline 2-82; Pipeline 3-83; Pipeline 4-84; Pipeline 5-85; Pipeline 6-86; Pipeline 11-811; Pipeline 7-87; Pipeline 8-88; Pipeline 9-89; Pipeline 10-810; Pipeline 11-811; First pump - 91; Sixth pump - 92; Seventh pump - 93; Eighth pump - 94; Ninth pump - 95; Third pump - 96; Fourth pump - 97; Fifth pump - 98; Tenth pump - 99; Eleventh pump - 910. Detailed Implementation

[0049] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0050] Example 1. As... Figure 1 , Figure 4 , Figure 8-10As shown, a calcium formate drying device includes a hot air duct 5 and a normal temperature air duct 51. A first vertical pipe 52 is movably connected to the bottom end of the hot air duct 5. A first feed inlet 54 is provided on the left side of the first vertical pipe 52. The first feed inlet 54 is connected to the outlet of a centrifuge 3 for solid-liquid separation of calcium formate liquid via a first feeder 53. The hot air duct 5, a horizontal pipe 55, and an absorption tower 7 are connected in sequence. A first cyclone separator 56 is connected to the hot air duct 5, and a screening device 57 is connected to the outlet of the first cyclone separator 56. The bottom end of the normal temperature air duct 51 is connected to... A second riser 58 is connected; a second feed inlet 511 is located on the left side of the bottom end of the second riser 58, and the second feed inlet 511 is connected to the outlet of the screening device 57 through a second feeder 510; the top of the ambient temperature air duct 51 is connected to the absorption tower 7; a second cyclone separator 59 is installed on the ambient temperature air duct 51; a first air inlet 521 connected to the hot air device is located on the bottom surface 524 of the first riser; a second air inlet 582 is located on the bottom surface 581 of the second riser; induced draft fans are installed at the ends of the horizontal pipe 55 and the ambient temperature air duct 51 near the absorption tower 7. The first feeder 53 is a screw conveyor. The second feeder 510 is a screw conveyor. In actual operation, the first air inlet 521 is connected to the hot air furnace 6 through the first connecting pipe 522, and high-temperature gas enters the first air inlet 521. The second air inlet 582 receives ambient temperature air. Calcium formate solids with a water content of less than 5% by weight, separated by centrifugation 3, are mixed with high-temperature gas entering from the first inlet 521. After separation by the first cyclone separator 56, the exhaust gas is discharged into the absorption tower. The solids separated by the first cyclone separator 56 are sieved by the screening device 57. The calcium formate in the room-temperature duct enters the room-temperature duct and is separated by the second cyclone separator 59 to obtain a dried finished product. The exhaust gas is then discharged into the absorption tower.

[0051] The top end of the first riser 52 is connected to the hot air duct 5 via the first connector 512; the top end of the second riser 58 is connected to the ambient temperature air duct 51 via the second connector 513. The horizontal pipe 55 is equipped with a first induced draft fan 71 near the absorption tower 7; the ambient temperature air duct 51 is equipped with a second induced draft fan 72 near the absorption tower 7.

[0052] Since the first riser has the highest volumetric heat transfer coefficient in the drying unit, it is most prone to crystallization adhering to its inner wall. This reduces the effective inner diameter of the first riser and makes online cleaning difficult. Therefore, a movable connection between the first riser and the first connecting pipe is adopted, allowing the first riser to be removed for cleaning or quick replacement at any time. The horizontal pipe design prevents condensate from flowing back into the first cyclone separator after drying, which could interfere with gas-solid mixing and reduce drying efficiency. The screened material undergoes a secondary drying process, resulting in better drying and facilitating particle size reduction and particle size distribution.

[0053] The diameter of the first riser 52 is larger than that of the hot air duct 5; the length of the first riser is 2.5m. The hot air duct has a diameter of 300mm and a length of 18m, and the diameter of the first riser is 1.5 times that of the hot air duct. The 18m length ensures that the wet material is fully heated and the moisture evaporates in the shortest possible time; the 1.5 times diameter of the first riser increases the contact time and contact area between the material and the hot air.

[0054] The hot air duct is thinner than the first riser, facilitating pressurized conveying and ensuring that the wet material is fully heated and its moisture evaporates in the shortest possible time. Since the material first comes into contact with the high-temperature, high-speed airflow in the first riser, its upward velocity is zero upon entering, resulting in the highest particle density, the greatest relative velocity between the gas and particles, and the highest volumetric heat transfer coefficient. The first riser, being thicker than the hot air duct, increases the contact time and area between the material and the hot air, allowing for thorough mixing and dispersion of the material before it enters the first hot air duct, resulting in excellent drying. The first riser 52 is 2.5m long, covering the area most prone to crystallization.

[0055] The bottom surface 524 of the first riser is arc-shaped, and the arc surface is tangent to the bottom surface of the first feeder 53 and the end of the inner wall of the first riser 52 away from the first feeder 53. The bottom surface of the first riser is set as an arc-shaped structure, which guides the incoming hot air to form a spiral upward airflow, avoiding the formation of vortices or dead corners in the airflow at the bottom of the riser. This allows the solid material fed by the first conveyor to be quickly entrained by the hot air and evenly dispersed, improving the gas-solid contact efficiency in the initial drying stage. The arc-shaped structure can also reduce the retention and accumulation of material at the bottom of the riser, preventing overheating, agglomeration, or crystal adhesion caused by local material aggregation.

[0056] The diameter of the second riser 58 is larger than the diameter of the normal temperature air duct 51; the bottom surface 581 of the second riser is an arc surface, which is tangent to the bottom surface of the second feeder 510 and the end of the inner wall of the second riser 58 away from the second feeder 510; the second air inlet 582 is connected to the filter 584 through the second connecting pipe 583. The filter 584 is used to filter air.

[0057] The bottom surface of the second riser is designed with an arc surface structure. This arc surface structure guides the incoming hot air to form a spiral upward airflow, avoiding the formation of vortices or dead corners in the airflow at the bottom of the riser. This allows the solid material fed in by the second conveyor to be quickly entrained by the hot air and evenly dispersed, improving the gas-solid contact efficiency in the initial drying stage. The arc surface structure can also reduce the retention and accumulation of material at the bottom of the riser, preventing overheating, agglomeration, or crystallization caused by localized material accumulation.

[0058] The first cyclone separator 56 and the second cyclone separator 59 have the same structure, both including a first-stage cyclone separator and a second-stage cyclone separator connected in series.

[0059] Specifically, the first cyclone separation device 56 includes a first-stage cyclone separator 561 and a first-stage cyclone separator 562 connected in series. The bottom end of the first-stage cyclone separator 561 and the first-stage cyclone separator 562 are connected to the screening device 57. The second cyclone separation device 59 includes a second-stage cyclone separator 591 and a second-stage cyclone separator 592 connected in series. The bottom end of the second-stage cyclone separator 591 and the second-stage cyclone separator 592 are connected to the finished product collection device 593.

[0060] Using this technical solution, the cyclone separator is mostly designed with dual separators, which has a high capture efficiency for fine particles and can solve the problem of some calcium formate fine powder being lost with the exhaust gas, reducing the product yield.

[0061] Calcium formate production equipment, such as Figure 1-10 As shown, it includes a reaction system, a transfer tank 2, a centrifuge 3, a mother liquor system, a hot air system, and the aforementioned drying device.

[0062] The reaction system includes several reaction groups, each reaction group including a reaction vessel 1 and at least two insulated stirring vessels 11 connected to the reaction vessel 1. In this embodiment, each reaction group includes two insulated stirring vessels 11.

[0063] Each insulated stirring vessel 11 is connected in sequence to the transfer tank 2 and the centrifuge 3; each reaction vessel 1 is connected to the powder silo 12 for holding calcium carbonate powder and the formic acid tank 13; each reaction vessel 1 and the insulated stirring vessel 11 is equipped with a stirrer.

[0064] Specifically, each reaction vessel 1 is equipped with a first stirrer 15, and the heat-insulating stirring vessel 11 is equipped with a second stirrer 111.

[0065] The mother liquor system includes a filter 41, a sedimentation tank 42, and a temporary storage tank 43. The top pipe of the side wall of the sedimentation tank 42 is equipped with an overflow port 421 connected to the evaporator 4 via a pipeline. The bottom end of the side wall of the sedimentation tank 42 is equipped with a waste liquid port 422 connected to the evaporator 4 via a pipeline. A slag discharge gate 424 is located at the bottom of the sedimentation tank 42. A supernatant port 423 connected to the temporary storage tank 43 via a pipeline is located in the middle of the side wall of the sedimentation tank 42. The outlet of the centrifuge 3, the filter 41, and the top of the sedimentation tank 42 are sequentially connected via pipelines. Each reactor 1 has an overflow hole 14 at its top, connected to the evaporator 4 via a pipeline. The top of each reactor 1 is connected to the temporary storage tank 43 via a pipeline. The height of the temporary storage tank 43 is greater than the height of each reactor 1.

[0066] The hot air system includes a first coil 61 located around the outer periphery of the horizontal pipe 55 and a hot air furnace 6. One end of the first coil 61 is connected to a gas distribution valve 62, and the other end is open. The gas distribution valve 62 is connected to the temporary storage tank 43 and each reaction vessel 1 via heat pipes 63. The first coil 61 is used to absorb heat from the horizontal pipe 55, heat the drawn-in cold air, and deliver it to the gas distribution valve 62. The gas distribution valve 62 is connected to the temporary storage tank 43 and each reaction vessel 1 via heat pipes 63, and is used to heat the temporary storage tank 43 and each reaction vessel 1.

[0067] The evaporator 4 is equipped with a second coil 44, and the hot air furnace 6 is connected in series with the second coil 44 and the bottom end of the first vertical pipe 52. The evaporator 4 is connected to the absorption tower 7.

[0068] The top of each reactor 1 and the top of each evaporator 4 are connected to the absorption tower 7 via exhaust pipes. The top of each reactor 1 is connected to the absorption tower 7 via a first exhaust pipe 113; the top of each evaporator 4 is connected to the absorption tower 7 via a second exhaust pipe 73.

[0069] Calcium carbonate powder and formic acid first undergo a preliminary reaction in a reactor, with the overflow separating light impurities. Then, the mixture enters a heated and stirred tank for further reaction, improving the reaction conversion rate and product purity, and reducing the burden of subsequent impurity treatment. Each reactor corresponds to at least two heated and stirred tanks, eliminating the time intervals between feeding, reaction, and discharging in traditional batch production, and avoiding the problems of long reaction times and discontinuous operation in a single reactor. Stirring is constant throughout the production process, eliminating sedimentation and waiting, and avoiding the risk of starting difficulties in the stirring device and motor burnout caused by impurity deposition. The mother liquor system, through filtration, sedimentation, temporary storage, and linkage with the evaporator, achieves the recovery and utilization of effective components in the mother liquor, reducing raw material loss. When the material reaches the horizontal tube, the material has already been dried. The first coil 61 absorbs the heat from the horizontal tube 55 and supplies heat to the temporary storage tank 43 and each reaction vessel 1 through the gas distribution valve 62 for production. This is relatively energy-efficient. The horizontal tube 55 is set horizontally to prevent the condensate in the dried gas from easily flowing back into the first cyclone separator.

[0070] Impurities and waste liquids are sorted and treated to reduce environmental pollution; the drying system is connected in series with the hot air furnace and evaporator, and the hot air first heats the evaporator before being used to dry the material, realizing the cascade utilization of thermal energy. In conjunction with the energy recovery system, the heat of the waste gas is recovered and used to heat the temporary storage tank and reaction vessel, improving energy utilization efficiency and reducing production energy consumption; the drying and cooling processes are combined, with two cyclone separation and screening devices to ensure the particle size of the finished product; the steam from the evaporator and the drying waste gas enter the absorption tower together for purification and discharge, reducing pollutant emissions.

[0071] like Figure 5 As shown, each pipeline is equipped with a liquid pump. Each insulated stirring vessel 11 is connected to the reaction vessel 1 through a first pipeline 81, and a first liquid pump 91 is installed on the first pipeline 81.

[0072] like Figure 2 , Figure 6 As shown, the overflow hole 14 at the top of each reaction vessel 1 is connected to the filter device 45 through the second pipeline 82, and the second pipeline 82 is equipped with a second liquid pump 821.

[0073] like Figure 6 As shown, the filtration device 45 is connected to the evaporator 4 via the twelfth pipe 46, and the twelfth pipe 46 is equipped with a twelfth liquid pump 461.

[0074] like Figure 3 As shown, the overflow port 421 is connected to the evaporator 4 through the third pipeline 83, and the third pipeline 83 is equipped with a third liquid pump 96.

[0075] like Figure 3 , Figure 7 As shown, the filter device 45 is located above the evaporator 4, and the waste liquid outlet 422 is connected to the evaporator 4 through the fourth pipeline 84; the fourth pipeline 84 is equipped with a fourth liquid pump 97.

[0076] like Figure 3 As shown, the supernatant port 423 is connected to the temporary storage tank 43 via the fifth pipeline 85. The fifth pipeline 85 is equipped with a fifth pumping pump 98.

[0077] like Figure 5 , Figure 6 As shown, each insulated stirring vessel 11 is connected to the transfer tank 2 through a sixth pipeline 86, and each sixth pipeline 86 has a sixth liquid pump 92.

[0078] like Figure 7 As shown, the transfer tank 2 is connected to the centrifuge 3 through the seventh pipeline 87, and the seventh pipeline 87 is equipped with a seventh liquid pump 93.

[0079] like Figure 3 , Figure 8 As shown, the outlet of centrifuge 3 is connected to filter 41 through the eighth pipeline 88, and the eighth pipeline 88 is equipped with an eighth pump 94.

[0080] like Figure 3 As shown, the filter 41 is connected to the top of the sedimentation tank 42 via the ninth pipeline 89, and the ninth pipeline 89 is equipped with a ninth liquid pump 95.

[0081] like Figure 3 As shown, the temporary storage tank is connected to the evaporation kettle 4 through the tenth pipe 810, and the tenth pump 99 is installed on the tenth pipe 810.

[0082] like Figure 2 As shown, the top of each reactor 1 is connected to the temporary storage tank 43 via the eleventh pipeline 811, and each eleventh pipeline 811 is equipped with an eleventh liquid pump 910.

[0083] like Figure 3 As shown, a third coil 431 is provided on the outer peripheral surface of the temporary storage tank 43, and a fourth coil 114 is provided on the outer peripheral surface of each reactor 1. The air inlet end 4311 of each third coil and the air inlet end 1141 of each fourth coil are respectively connected to the gas distribution valve 62 through a heat pipe 63. The air outlet end 4312 of each third coil and the air outlet end 1142 of each fourth coil are open. Figure 8-9 As shown, the first air inlet 521 is connected to the second coil 44 through the first connecting pipe 522; the first connecting pipe 522 is equipped with an induced draft pump 523.

[0084] like Figure 2 As shown, each heat pipe 63 is equipped with a first air pump 631. For example... Figure 4 As shown, the first coil 61 is connected to the air distribution valve 62 via a connecting pipe 621, and a second air pump 622 is provided on the connecting pipe 621.

[0085] like Figure 2 As shown, the bottom of the powder silo 12 is connected to the distribution silo 17 via the first screw feeder 16. The distribution silo 17 is connected to a weighing silo 19 via two second screw feeders 18. Each weighing silo 19 is connected to a transfer silo 111 via a third screw feeder 110. Each reactor 1 is connected to the transfer silo 111 via a fourth screw feeder 112. The transfer silo 111 is located above each reactor 1. Each reactor 1 is connected to a formic acid tank 13 via a formic acid pipe 131. A formic acid pump 132 is installed on the formic acid pipe 131. The formic acid tank 13 is located above each reactor 1.

[0086] The operating method of any of the above-mentioned calcium formate production devices is characterized by comprising the following steps: Step 1: Calcium carbonate powder from powder silo 12 and formic acid from formic acid tank 13 are fed into each reaction vessel 1 for mixing and reaction. When the liquid level in reaction vessel 1 exceeds the height of overflow hole 14, the liquid rich in light impurities on the surface of the mixed reaction liquid is discharged into evaporator 4 through top overflow hole 14. The weight ratio of calcium carbonate to formic acid is 1:0.83, the temperature is 60 degrees Celsius, and the stirring speed is 60 rpm.

[0087] Step 2: The mixed reaction materials are fed into a heated stirred tank 11 in the same group, where continuous stirring completes the deep reaction. The reacted materials are then temporarily stored in a transfer tank 2 and subsequently pumped into a centrifuge 3 for solid-liquid separation. The stirring speed is 60 rpm, and the reaction time in the heated stirred tank 11 is 15–60 minutes. This process helps the crystals grow fully, forming uniform, free-flowing "flowing sand" calcium formate crystals.

[0088] Step 3: The solid material separated by centrifuge 3 is discharged from the outlet, and the mother liquor is sent to filter 41 through the outlet to filter insoluble impurities. The filtered mother liquor enters the sedimentation tank 42 for settling. The liquid containing floating impurities in the upper layer of sedimentation tank 42 enters the evaporator 4 through the overflow port 421 of the side wall top pipe. The waste liquid rich in insoluble impurities at the bottom flows into the evaporator 4 through the fourth pipeline 84. The supernatant is drawn through the supernatant port 423 and enters the temporary storage tank 43. The sludge is discharged from the bottom of sedimentation tank 42 periodically through the sludge discharge door 424.

[0089] Step 4: The solid material discharged from centrifuge 3 enters the first riser 52 via the first feeder 53. The hot air generated by the hot air furnace 6 first flows through the second coil 44 around the evaporator 4 to heat it, and then enters the first riser 52 from the bottom end to mix with the material. The dried material enters the first cyclone separator 56 with the airflow, and the separated material is sent to the screening device 57 for grading. The high-temperature gas generated by the hot air furnace 6 is not lower than 380 degrees Celsius, and the hot air entering the first riser 52 from the bottom end is not lower than 180 degrees Celsius.

[0090] Step 5: The qualified material after screening enters the second riser 58 through the second feeder 510, and cold air is introduced into the second riser 58 to dry the material; the material is separated by the second cyclone separator 59 to obtain the calcium formate product.

[0091] Step 6: Cold air is introduced into the first coil 61 around the outer periphery of the horizontal pipe 55 to recover the heat of the waste gas in the pipe and form a hot airflow. The temperature of the hot airflow is not lower than 120 degrees Celsius. The liquid temperature in the temporary storage tank is controlled at 50 degrees Celsius, and the temperature of the reaction vessel is controlled at 60 degrees Celsius. The hot airflow is transferred through the gas distribution valve 62 and heat pipe 63 to the temporary storage tank 43 and the reaction vessel 1 for heating. The steam generated by the evaporator 4 and the waste gas from the drying system enter the absorption tower 7 for purification before being discharged.

Claims

1. A calcium formate drying device, characterized in that: The system includes a hot air duct and a normal temperature air duct. The bottom of the hot air duct is movably connected to a first vertical pipe, and the first vertical pipe has a first feed inlet on its side. The first feed inlet is connected to the outlet of a centrifuge used for solid-liquid separation of calcium formate liquid via a first feeder. The hot air duct, horizontal pipe, and absorption tower are connected in sequence. A first cyclone separator is connected to the hot air duct, and the outlet of the first cyclone separator is connected to a screening device. The bottom of the normal temperature air duct is connected to a second vertical pipe. A second feed inlet is located on one side of the bottom of the second vertical pipe, and the second feed inlet is connected to the outlet of the screening device via a second feeder. The top of the normal temperature air duct is connected to the absorption tower. A second cyclone separator is installed on the normal temperature air duct. The bottom surface of the first vertical pipe has a first air inlet connected to the hot air device. The bottom surface of the second vertical pipe has a second air inlet. Exhaust fans are installed at the ends of the horizontal pipe and the normal temperature air duct near the absorption tower.

2. The calcium formate drying apparatus as described in claim 1, characterized in that: The diameter of the first riser is larger than the diameter of the hot air duct; the length of the first riser is not less than 2.5m.

3. The calcium formate drying apparatus as described in claim 1, characterized in that: The bottom surface of the first riser is an arc surface, which is tangent to the bottom surface of the first feeder and the inner side wall of the first riser away from the first feeder.

4. The calcium formate production apparatus as described in claim 1, characterized in that: The diameter of the second riser is larger than that of the normal temperature air duct; the bottom surface of the second riser is an arc surface, which is tangent to the bottom surface of the second feeder and the end of the inner wall of the second riser away from the second feeder; the second air inlet is connected to the filter through the second connecting pipe.

5. The calcium formate production apparatus as described in claim 1, characterized in that: The first cyclone separator and the second cyclone separator have the same structure, both including a first-stage cyclone separator and a second-stage cyclone separator connected in series.

6. A calcium formate production apparatus, characterized in that: Includes a reaction system, a transfer tank, a centrifuge, a mother liquor system, a hot air system, and a drying device as described in any one of claims 1-5; The reaction system includes several reaction groups, each reaction group including a reaction vessel and at least two insulated stirring vessels connected to the reaction vessel; each insulated stirring vessel is connected in sequence to a transfer tank and a centrifuge; each reaction vessel is connected to a powder silo for holding calcium carbonate powder and a formic acid tank; each reaction vessel and insulated stirring vessel is equipped with a stirrer. The mother liquor system includes a filter, a sedimentation tank, and a temporary storage tank. The top pipe of the sedimentation tank's side wall is equipped with an overflow port connected to the evaporator via a pipeline. The bottom end of the sedimentation tank's side wall is equipped with a waste liquid port connected to the evaporator via a pipeline. A slag discharge gate is located at the bottom of the sedimentation tank. A supernatant port connected to the temporary storage tank via a pipeline is located in the middle of the sedimentation tank's side wall. The centrifuge's outlet, the filter, and the top of the sedimentation tank are sequentially connected via pipelines. Each reaction vessel has an overflow hole at its top connected to the evaporator via a pipeline. The top of each reaction vessel is connected to the temporary storage tank via a pipeline. The hot air system includes a first coil located on the outer periphery of the horizontal pipe and a hot air furnace. One end of the first coil is connected to a gas distribution valve, and the other end is open. The gas distribution valve is connected to a temporary storage tank and each reaction vessel through heat pipes. The evaporator is equipped with a second coil, and the hot air furnace is connected in series with the second coil and the bottom of the first vertical pipe. The evaporator is connected to the absorption tower.

7. The calcium formate production apparatus as described in claim 6, characterized in that: The tops of each reactor and evaporator are connected to the absorption tower via exhaust pipes.

8. The calcium formate production apparatus as described in claim 7, characterized in that: Each pipeline is equipped with a liquid pump.

9. The calcium formate production apparatus as described in claim 7, characterized in that: A third coil is provided on the outer surface of the temporary storage tank, and a fourth coil is provided on the outer surface of each reactor. The air inlet of each third coil and the air inlet of each fourth coil are connected to the gas distribution valve through a heat pipe. The air outlet of each third coil and the air outlet of each fourth coil are open. A first air pump is provided on each heat pipe. The first coil is connected to the gas distribution valve through a connecting pipe, and a second air pump is provided on the connecting pipe. The first air inlet is connected to the second coil through the first connecting pipe. An induced draft pump is provided on the first connecting pipe.

10. The calcium formate production apparatus as described in claim 6, characterized in that: The bottom of the powder silo is connected to the distribution silo via a first screw feeder. The distribution silo is connected to a weighing silo via two second screw feeders. Each weighing silo is connected to a transfer silo via a third screw feeder. Each reactor is connected to the transfer silo via a fourth screw feeder. The transfer silo is located above each reactor. Each reactor is connected to a formic acid tank via a formic acid pipe. A formic acid pump is installed on the formic acid pipe. The formic acid tank is located above each reactor.

11. The method of operating the calcium formate production apparatus according to any one of claims 6-10, characterized in that, Includes the following steps: Step 1: Send the calcium carbonate powder from the powder silo and the formic acid from the formic acid tank into each reactor for mixing and reaction; when the liquid level in the reactor exceeds the height of the overflow hole, discharge the liquid rich in light impurities on the surface of the mixed reaction liquid into the evaporation reactor through the top overflow hole; Step 2: The mixed reaction materials are fed into a heated stirred tank in the same group and stirred continuously to complete the deep reaction; the reacted materials are transported to a transfer tank for temporary storage, and then pumped into a centrifuge for solid-liquid separation; Step 3: The solid material separated by the centrifuge is discharged from the outlet, and the mother liquor is sent to the filter through the outlet to filter insoluble impurities. The filtered mother liquor enters the sedimentation tank for settling. The liquid containing floating impurities in the upper layer of the sedimentation tank enters the evaporation kettle through the overflow port of the top pipe on the side wall, and the waste liquid rich in insoluble impurities at the bottom flows into the evaporation kettle through the fourth pipe. The supernatant is drawn through the supernatant port into the temporary storage tank. The sludge at the bottom of the sedimentation tank is periodically opened to discharge the sediment. Step 4: The solid material discharged from the centrifuge enters the first vertical pipe through the first feeder. The hot air generated by the hot air furnace first flows through the second coil around the outer periphery of the evaporator to heat it, and then enters the interior of the first vertical pipe from the bottom end to mix with the material. The dried material enters the first cyclone separator with the airflow, and the separated material is sent to the screening device for grading. Step 5: The qualified material after screening enters the second vertical pipe through the second feeder, and cold air is introduced into the second vertical pipe to dry the material; the material is separated by the second cyclone separator to obtain calcium formate product; Step 6: Cold air is introduced into the first coil around the outer periphery of the horizontal pipe to recover the heat of the waste gas in the pipe and form a hot air flow. The hot air flow is transferred through the gas distribution valve and heat pipe to the temporary storage tank and the reaction vessel for heating. The steam generated by the evaporation vessel and the waste gas of the drying system enter the absorption tower for purification before being discharged.

Images