A sodium carbonate evaporation and drying system

Abstract

This invention discloses a sodium carbonate evaporation and drying system, aiming to address the shortcomings of existing sodium carbonate extraction systems, such as low evaporation efficiency and high energy consumption. The invention includes an evaporation section and a drying section. The evaporation section comprises a double-effect evaporator, a crystallizer, and a thickener arranged in series. The drying section includes a screw conveyor, a steam radiator, and a vibrating fluidized bed. The double-effect evaporator is also connected to a steam compressor. The steam compressor compresses and heats the steam generated in the double-effect evaporator before returning it to the evaporator. The steam radiator connects to a fresh steam pipe and an air pipe, heating the air with steam. The air pipe connects to the vibrating fluidized bed, and the heated air heats the material in the vibrating fluidized bed. By utilizing the high-temperature steam generated by the steam compressor to simultaneously heat the air source for both the evaporator and the vibrating fluidized bed aeration, efficient reuse is achieved, reducing the number of devices and improving heat utilization efficiency.

Description

Technical Field

[0001] This utility model relates to the field of evaporation and concentration, and more specifically, to a sodium carbonate evaporation and drying system. Background Technology

[0002] Sodium carbonate, as an important basic chemical raw material, is widely used in many fields such as glass, chemical industry, metallurgy, textiles, and food. With the continuous development of various industries, the demand for sodium carbonate is increasing year by year, while higher requirements are being placed on its quality and production efficiency. In the sodium carbonate production process, the evaporation process is a key step in achieving solution concentration and crystal precipitation; its energy consumption and operating efficiency directly affect the cost and benefits of the entire production process. Traditional sodium carbonate evaporation systems suffer from high energy consumption, low evaporation efficiency, and unstable product quality, making it difficult to meet the current industry's needs for energy conservation, emission reduction, and high-quality development.

[0003] Chinese Patent CN116966849A discloses a sodium carbonate recovery system and a method for recovering sodium carbonate from PTA organic residue using this system. In this system, a dissolving tank A, a filter, an evaporation feed tank, and an evaporator A are connected in sequence; evaporator A, evaporator B, and a recovery tank are connected in sequence; evaporator A, a thickener A, a centrifuge A, and a screw A are connected in sequence, with screw A connected to both a drying system and dissolving tank B; evaporator B, thickener B, centrifuge B, and screw B are connected in sequence, with screw B connected to dissolving tank B; evaporator A is connected to condenser A, and condenser A is connected to both dissolving tank A and dissolving tank B; evaporator B, condenser B, and dissolving tank B are connected in sequence; and dissolving tank B is connected to the main system.

[0004] This system can effectively recover sodium carbonate, but its thermal efficiency is relatively low and its energy consumption is high. This application aims to improve its thermal efficiency and reduce energy consumption. Utility Model Content

[0005] This invention overcomes the shortcomings of existing sodium carbonate extraction systems, such as low evaporation efficiency and high energy consumption, and provides a sodium carbonate evaporation and drying system with good thermal utilization efficiency and low energy consumption.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A sodium carbonate evaporation and drying system includes an evaporation section and a drying section. The evaporation section includes a first heating evaporator, a second heating evaporator, a crystallizer, and a thickener arranged in series. The drying section includes a screw conveyor, a steam radiator, and a vibrating fluidized bed. The first heating evaporator and the second heating evaporator are also connected to a steam compressor. The steam compressor compresses and heats the steam generated in the first heating evaporator and the second heating evaporator and then sends it back to the first heating evaporator and the second heating evaporator. The steam radiator is connected to a fresh steam pipe and an air pipe and heats the air with steam. The air pipe is connected to the vibrating fluidized bed, and the heated air heats the material in the vibrating fluidized bed.

[0008] This application relates to the evaporation and drying of waste liquid containing sodium carbonate to obtain crystalline sodium carbonate crystals. A double-effect evaporator is used in series. A steam compressor compresses the steam generated during evaporation and separation, increasing its calorific value. The steam is then reinjected into the evaporator as a heat source to raise the temperature of the liquid. Evaporation and separation are then carried out under low pressure, thus reusing the steam and utilizing the heat it contains. A technical structure conceivable to those skilled in the art but not mentioned in this application includes a condenser and a vacuum pump. The condenser condenses excess steam, and the vacuum pump is connected to the end of the second evaporator to generate negative pressure, providing the power to transfer the material from the first to the second evaporator. The steam passing through the condenser and the non-condensable gases generated in the evaporation section also preheat the material through a heat exchanger-type condenser, reusing its heat.

[0009] The material concentrated in the double-effect evaporator is passed through a crystallizer and thickener to obtain a mixture of water and sodium carbonate. The mixture then enters the drying section for further processing. Conveyed by a screw conveyor, the mixture is fluidized by a vibrating fluidized bed through vibration, and combined with a high-temperature airflow, the moisture in the mixture is dried to obtain fully dried sodium carbonate crystals.

[0010] It also uses high-temperature fresh steam as a heat source to exchange heat with the air, increasing the calorific value of the air and sending it into the vibrating fluidized bed as a high-temperature airflow. During the contact with the material, it removes moisture and improves the drying efficiency.

[0011] Therefore, this application, by pressurizing the secondary steam for use in the evaporation section and using fresh high-temperature steam generated by other systems as a heat source, has good thermal utilization efficiency and low energy consumption.

[0012] Preferably, both the first and second heating evaporators include heaters and separators. The evaporation section also includes a mother liquor tank and a centrifuge. The centrifuge's inlet is connected to a crystallizer tank, the mother liquor tank is connected to the clear liquid outlet of the centrifuge, and the turbid liquid outlet of the centrifuge is connected to a thickener. The mother liquor tank is connected to the second heating evaporator. The heater and separator are circulated together via pipes and a circulating pump. After the crystals and mother liquor produced in the crystallizer tank are separated by the centrifuge, the mother liquor is returned to the internal circulation of the second heating evaporator. When the mixture of mother liquor and feed liquid reaches a supersaturated concentration, crystals precipitate again in the crystallizer tank, and are separated again by the centrifuge, thus completing the cycle.

[0013] Preferably, the evaporation section also includes a dissolving mother liquor tank and a dissolving centrifuge. The inlet of the dissolving centrifuge is connected to a thickener, the solid outlet of the dissolving centrifuge is connected to a screw conveyor, the liquid outlet of the dissolving centrifuge is connected to the dissolving mother liquor tank, and the liquid outlet of the dissolving mother liquor tank is connected in parallel with the mother liquor tank.

[0014] Preferably, the feed liquid produced by the first heating evaporator is fed into the upper part of the separator of the second heating evaporator through a pipeline, and the feed liquid is also fed into the lower part of the separator of the second heating evaporator through a pipeline. This connection method facilitates thorough mixing of the higher concentration feed liquid and the lower concentration feed liquid.

[0015] Preferably, air is connected to a hot air blower via an air duct, and the hot air blower is connected to a steam radiator. The air is preheated by the hot air blower before entering the steam radiator, thereby further increasing the temperature of the air passing through the steam radiator and achieving a better drying effect.

[0016] Preferably, the bottom of the vibrating fluidized bed is provided with several aeration ports, at least some of which are connected to the air duct of the steam radiator. Heated air enters from the bottom aeration ports of the vibrating fluidized bed, uniformly agitating the moist crystals in the bed and improving the dryness of the crystals.

[0017] As a preferred option, the hot air blower is also connected to a cold air duct, which is directly connected to some of the aeration ports.

[0018] Preferably, the aeration port of the air duct connected to the steam radiator is located near the inlet of the vibrating fluidized bed, and the aeration port connected to the cold air duct is located near the outlet of the vibrating fluidized bed. This arrangement provides a gradient drying process for the moist crystals. The initial section of the vibrating fluidized bed, from the inlet, is dried with high-temperature air, and after significant drying, the subsequent section utilizes relatively cooler air for further drying. This reduces heat waste and maximizes heat utilization.

[0019] Preferably, the system also includes a dust collector, comprising a cyclone dust collector and / or a water film dust collector, connected to the top of the vibrating fluidized bed. The dust collector removes dust from the air exiting the vibrating fluidized bed, collecting larger dust particles using the cyclone dust collector and then absorbing the remaining dust in the air using the water film dust collector. It is worth noting that the water source for the water film dust collector can be the condensate produced in the aforementioned evaporation section.

[0020] Compared with the prior art, the beneficial effects of this utility model are:

[0021] The high-temperature steam generated by the steam compressor is used to heat both the evaporator and the air source for the vibrating fluidized bed aeration, achieving efficient reuse, reducing the number of equipment and improving the efficiency of heat utilization. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the liquid flow in the evaporation section;

[0023] Figure 2 This is a schematic diagram of the drying section;

[0024] Figure 3 This is a schematic diagram of the steam flow of this utility model;

[0025] In the picture:

[0026] First heating evaporator 1, second heating evaporator 2, crystallizer tank 3, thickener 4, steam compressor 5, heater 6, separator 7, mother liquor tank 8, centrifuge 9, dissolving mother liquor tank 10, dissolving centrifuge 11, screw conveyor 12, vibrating fluidized bed 13, hot air blower 14, steam radiator 15, cyclone dust collector 16, water film dust collector 17. Detailed Implementation

[0027] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relational terms determined for the convenience of describing the structural relationships of various components or elements of the present disclosure, and do not specifically refer to any component or element in the present disclosure, and should not be construed as a limitation to the present disclosure.

[0031] In the present disclosure, terms such as "fixed connection", "connected", "joined" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those skilled in the relevant scientific research or technology in this field, the specific meanings of the above terms in the present disclosure can be determined according to specific circumstances, and should not be construed as a limitation to the present disclosure.

[0032] Embodiment:

[0033] A sodium carbonate evaporation drying system includes an evaporation section and a drying section.

[0034] Refer Figure 1 As shown, the evaporation section includes a first heating evaporator 1, a second heating evaporator 2, a crystal slurry tank 3 and a thickener 4 which are arranged in series. Among them, the first heating evaporator 1 and the second heating evaporator 2 are a plate falling film evaporator and a forced circulation evaporator respectively.

[0035] Refer Figure 3 As shown, the first heating evaporator 1 and the second heating evaporator 2 are also connected with a steam compressor 5. The two-effect heating evaporators are used in series. The steam generated by evaporation separation is compressed by the steam compressor ⑤ to increase the calorific value of the steam, and then the steam is re-injected into the heating evaporator as a heat source to increase the temperature of the feed liquid, and then evaporation separation is carried out by means of a low-pressure environment, so as to achieve the reuse of steam and the reuse of the heat contained in the steam. Technical structures that can be thought of by those skilled in the art and not mentioned in this application include a condenser and a vacuum pump. The condenser condenses the excess steam generated, and the vacuum pump is connected to the end of the second heating evaporator 2 to generate negative pressure, generating the power to transfer the material from the first heating evaporator 1 to the second heating evaporator 2. Among them, the steam passing through the condenser and the non-condensable gas generated in the evaporation section also preheat the passing material through a condenser in the form of a heat exchanger, and reuse its heat.

[0036] Both the first heating evaporator 1 and the second heating evaporator 2 include a heater 6 and a separator 7. For the second heating evaporator 2, the feed liquid generated by the first heating evaporator 1 is sent into the upper part of the separator 7 of the second heating evaporator 2 through a pipeline, and the raw feed liquid is also sent into the lower part of the separator 7 of the second heating evaporator 2 through a pipeline. The above connection method is conducive to the full mixing of the feed liquid with a higher concentration and the feed liquid with a lower concentration.

[0037] The evaporation section further includes a mother liquor tank 8 and a centrifuge 9. The feed inlet of the centrifuge 9 is connected to the crystal slurry tank 3. The mother liquor tank 8 is connected to the clear liquid outlet of the centrifuge 9. The turbid liquid outlet of the centrifuge 9 is connected to the thickener 4. The mother liquor tank 8 is connected to the second heating evaporator 2. The heater 6 and the separator 7 are connected in circulation through pipelines and a circulation pump. The crystals and mother liquor generated by the crystal slurry tank 3 are separated by the centrifuge 9, and the mother liquor is sent back to the internal circulation of the second heating evaporator 2. After the mixture of the mother liquor and the feed liquid reaches the supersaturated concentration, crystals are precipitated again in the crystal slurry tank 3, and the crystals are separated again by the centrifuge 9, and so on in a cycle.

[0038] The evaporation section further includes a dissolved mother liquor tank 10 and a dissolved centrifuge 11. The feed inlet of the dissolved centrifuge 11 is connected to the thickener 4. The solid discharge outlet of the dissolved centrifuge 11 is connected to the screw conveyor 12. The liquid discharge outlet of the dissolved centrifuge is connected to the dissolved mother liquor tank 10. The liquid outlet of the dissolved mother liquor tank 10 is connected in parallel with the mother liquor tank 8.

[0039] See Figure 2 As shown, the drying section includes a screw conveyor 12, a steam radiator 15 and a vibrating fluidized bed 13. Fresh steam exchanges heat with the air sent into the vibrating fluidized bed 13 through the evaporation radiator. The air is supplied from an external air source.

[0040] The air is connected to a hot air blower 14 through an air pipeline. The hot air blower 14 is connected to the steam radiator 15. The steam radiator 15 is connected to a steam pipeline. The air is preheated by the hot air blower 14 before entering the steam radiator 15, so as to further increase the temperature of the air passing through the steam radiator 15 and achieve a better drying effect. A number of aeration ports are provided at the bottom of the vibrating fluidized bed 13, and at least some of the aeration ports are connected to the air pipeline of the steam radiator 15. The heated air enters from the bottom aeration ports of the vibrating fluidized bed 13 and evenly blows the wet crystals in the vibrating fluidized bed 13 to improve the drying degree of the crystals. The hot air blower 14 is also connected to a cold air pipe, and the cold air pipe is directly connected to some of the aeration ports. Among them, the aeration ports of the air pipeline connected to the steam radiator 15 are close to the inlet of the vibrating fluidized bed 13, and the aeration ports connected to the cold air pipe are close to the outlet of the vibrating fluidized bed 13. The above setting performs gradient drying on the wet crystals. The front section of the vibrating fluidized bed 13 entered from the inlet is dried by high-temperature air, and after being largely dried, the rear section of the vibrating fluidized bed 13 uses air with a relatively lower temperature for drying, which can reduce heat waste and achieve full utilization of heat.

[0041] The drying section also includes a dust collector, comprising a cyclone dust collector 16 and / or a water film dust collector 17, which is connected to the top of the vibrating fluidized bed 13. The dust collector removes dust from the air discharged from the vibrating fluidized bed 13. Larger dust particles are collected by the cyclone dust collector 16, and the remaining dust in the air is absorbed by the water film dust collector 17. It is worth noting that the water source for the water film dust collector 17 can be the condensate generated in the aforementioned evaporation section. The washing water after cleaning is then discharged from the water film dust collector 17 to the outside for further treatment.

[0042] This application is used for evaporating and drying waste liquid containing sodium carbonate to obtain crystalline sodium carbonate crystals.

[0043] The material concentrated by the double-effect evaporator is passed through the crystal slurry tank 3 and the thickener 4 to obtain a mixture of water and sodium carbonate. The mixture then enters the drying section for further processing. The mixture is conveyed by a screw conveyor, and the vibrating fluidized bed 13 achieves fluidization through vibration, combined with aeration to dry the moisture in the mixture, resulting in fully dried sodium carbonate crystals.

[0044] The steam generated by the steam compressor 5 is partially fed into the double-effect evaporator as a heat medium. Fresh steam is used as a heat source for heat exchange with air, increasing the air's calorific value, and is then fed into the vibrating fluidized bed 13 for aeration, improving drying efficiency. Additionally, fresh steam is also piped into the small double-effect evaporator as a heat medium during the start-up phase.

[0045] The raw materials are divided into two streams. One stream, after being preheated by a preheater, enters the first heating evaporator 1. The resulting concentrated material enters the separator 7 of the second heating evaporator 2. The other stream of raw materials also enters the separator 7, with the concentrated material at the top and the raw material at the bottom. The secondary concentrated material produced by the second heating evaporator 2 continues to evaporate and enters the crystal slurry tank 3. The crystals precipitated from the supersaturated material in the crystal slurry tank 3 are separated by a centrifuge. The clear liquid is connected to the mother liquor tank 8, and the turbid liquid enters the thickener 4. The clear liquid in the mother liquor tank 8 returns to the second heating evaporator 2. The concentration of the turbid liquid in the thickener 4 further increases, and the solid and liquid phases are initially separated. Then, it enters the dissolving centrifuge 11 for further centrifugation. The resulting solution enters the dissolving mother liquor tank 10. The dissolving mother liquor tank 10 is connected in parallel with the mother liquor tank 8, and the solution is sent back to the second heating evaporator 2. The resulting moist crystals are sent to the drying section.

[0046] The moist crystals are fed into the vibrating fluidized bed 13 via the screw conveyor 12. The air is heated by the hot air blower 14 and / or by steam to dry the moist crystals. The dried crystals are then output to the outside of the system via a vibrating screen.

[0047] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A sodium carbonate evaporation drying system characterized by, The device includes an evaporation section and a drying section. The evaporation section includes a first heating evaporator, a second heating evaporator, a crystallizer, and a thickener arranged in series. The drying section includes a screw conveyor, a steam radiator, and a vibrating fluidized bed. The first heating evaporator and the second heating evaporator are also connected to a steam compressor. The steam compressor compresses and heats the steam generated in the first heating evaporator and the second heating evaporator and then sends it back to the first heating evaporator and the second heating evaporator. The steam radiator is connected to a fresh steam pipe and an air pipe and heats the air with steam. The air pipe is connected to the vibrating fluidized bed, and the heated air heats the material in the vibrating fluidized bed.

2. A sodium carbonate evaporation drying system according to claim 1, wherein, Both the first and second heating evaporators include heaters and separators. The evaporation section also includes a mother liquor tank and a centrifuge. The inlet of the centrifuge is connected to the crystal slurry tank, the mother liquor tank is connected to the clear liquid outlet of the centrifuge, the turbid liquid outlet of the centrifuge is connected to a thickener, and the mother liquor tank is connected to the second heating evaporator.

3. A sodium carbonate evaporation drying system according to claim 2, wherein, The evaporation section also includes a dissolving mother liquor tank and a dissolving centrifuge. The feed inlet of the dissolving centrifuge is connected to a thickener, the solid outlet of the dissolving centrifuge is connected to a screw conveyor, the liquid outlet of the dissolving centrifuge is connected to the dissolving mother liquor tank, and the liquid outlet of the dissolving mother liquor tank is connected in parallel with the mother liquor tank.

4. The sodium carbonate evaporation drying system of claim 1, wherein, The feed liquid generated by the first heating evaporator is sent through a pipeline to the upper part of the separator of the second heating evaporator, and the feed liquid is also sent through a pipeline to the lower part of the separator of the second heating evaporator.

5. The sodium carbonate evaporation and drying system according to claim 1, characterized in that, Air is connected to a hot air blower via an air duct, and the hot air blower is connected to a steam radiator.

6. The sodium carbonate evaporation and drying system according to claim 5, characterized in that, The bottom of the vibrating fluidized bed is equipped with several aeration ports, and at least some of the aeration ports are connected to the air ducts of the steam radiator.

7. The sodium carbonate evaporation and drying system according to claim 6, characterized in that, The hot air blower is also connected to a cold air duct, which is directly connected to some of the aeration ports.

8. The sodium carbonate evaporation and drying system according to claim 7, characterized in that, The aeration port of the air duct connected to the steam radiator is close to the inlet of the vibrating fluidized bed, and the aeration port connected to the cold air duct is close to the outlet of the vibrating fluidized bed.

9. A sodium carbonate evaporation and drying system according to claim 1, characterized in that, It also includes a dust collector, which includes a cyclone dust collector and / or a water film dust collector, the dust collector being connected to the top of the vibrating fluidized bed.

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