Device for preparing heavy soda ash based on hot alkali liquor

Abstract

The utility model relates to the technical field of devices for preparing heavy soda ash based on hot alkali liquor, and discloses a device for preparing the heavy soda ash based on the hot alkali liquor, which adopts the following technical scheme that two groups of pipelines are arranged on one side of a reaction tank and are respectively used for placing the hot alkali liquor and liquid alkali; the reaction tank is used for reacting hot alkali liquor with liquid alkali and reducing the content of bicarbonate radicals in the hot alkali liquor, an ammonia still is arranged on one side of the reaction tank, the ammonia still is communicated with the reaction tank through a pipeline, and a liquid blending pump is arranged on the pipeline. Sodium bicarbonate in hot alkali liquor is completely converted into sodium carbonate in a mode of heating the hot alkali liquor or adding liquid alkali into the hot alkali liquor, the problems of pipeline blockage, equipment scabbing and the like caused by relatively small solubility of the sodium bicarbonate are avoided, and the converted hot alkali liquor can be used for preparing common heavy ash through solid-phase hydration. And the method can be used for preparing high-quality heavy ash by liquid-phase hydration, and can be flexibly adjusted according to market requirements and actual production conditions.

Description

Technical Field

[0001] This utility model relates to the technical field of apparatus for preparing heavy soda ash based on hot alkaline solution, specifically an apparatus for preparing heavy soda ash based on hot alkaline solution. Background Technology

[0002] The decreasing demand for soda ash solution for calcium removal in Qinghai Alkali Industry's brine system leads to prolonged hot soda ash circulation time and increased concentration, sometimes exceeding 80 tt. This affects the scrubbing effect on light ash gas and can cause blockages in the hot soda ash tower. The calcination workshop diverts some of the dust removal soda ash solution to the heavy ash condensate, mixes it, and then replenishes the dust removal tank. However, the effect is unsatisfactory; the amount of hot soda ash solution used is low, and the high soda ash concentration remains a problem. Furthermore, excess soda ash in the brine results in waste, and the concentration of soda ash in the heavy ash condensate used for hydration is also too low.

[0003] Hot alkali solution from the calcination workshop was sent to the sodium bicarbonate workshop to produce qualified sodium bicarbonate products. However, the recovery effect was unsatisfactory, with high alkali consumption in the sodium bicarbonate workshop. Furthermore, the operation suffered from large fluctuations in the concentration of the hot alkali solution, an undersized hot alkali solution tank, and narrow pipelines for transporting the hot alkali solution. To address these issues, Shuanghuan modified the hot alkali solution recovery process. Piping was added between the hot alkali solution tank and the hot alkali solution tower, and an additional hot alkali solution tank was added to increase the storage and circulation volume of the hot alkali solution, reducing the rate of concentration increase. The pipeline for transporting the hot alkali solution was changed from φ57mm to φ78mm to increase the transport volume, forming a closed loop of old system → new system → sodium bicarbonate → old system. In addition, the hot alkali solution was used for brine purification, solving the hot alkali solution utilization problem and reducing the consumption of soda ash during brine purification, thus lowering production costs.

[0004] The treatment of alkali dust from furnace gas at Dahua Group employs a cyclone separator combined with a hot alkali washing process. The recovered hot alkali solution, containing 35-45 tt of alkali and less than 6 tt of ammonia, is primarily used for caustic soda production. However, due to the high cost of caustic soda production, market sales are declining, leading to a decrease in the use of hot alkali solution. Dahua lacks a sodium bicarbonate workshop, and its brine refining process uses the ammonium bicarbonate-lime method, leaving the hot alkali solution with no other outlet besides caustic soda production. This results in a large-scale discharge of hot alkali solution, causing significant economic losses and environmental pollution. Therefore, Dahua Group has implemented a system to remove carbon dioxide and ammonia from the hot alkali solution through heating before using it in nitrate production, thus achieving complete reuse of the hot alkali solution.

[0005] The calcium and magnesium content of the crude brine was significantly reduced, thus decreasing the demand for hot alkali solution in the brine process. The surplus of hot alkali solution was approximately 20 m³ / h, so an attempt was made to use the calcined hot alkali solution in heavy ash production. Initially, the hot alkali solution was introduced into the solid-phase hydration process, where the temperature of the hydration water rose to 55℃. To avoid affecting the crystallization quality of monohydrate alkali due to the increased temperature, a corrugated tube heat exchanger for the hydration water was used. However, during the trial period, problems such as poor crystallization and large lumps of monohydrate alkali still occurred, and the particle size of the product from the solid-phase heavy ash system was significantly reduced. Subsequently, experiments were conducted in the liquid-phase hydration system. During the experiment, problems such as blockages in the centrifuge hydrocyclone inlet pipeline, mother liquor tank outlet pipeline, and crystallizer outlet pipeline, as well as increased current in the centrifuge and mother liquor pump, occurred. The experiment was ultimately stopped due to blockage in the mother liquor tank outlet pipeline. The particle size of the heavy ash produced during the experiment was also significantly lower than before the experiment.

[0006] The brine workshop switched from large-particle sea salt to powdered salt with low calcium and magnesium content, resulting in a decrease in the demand for hot alkali solution in the brine refining process. To address this, the Lianyungang Alkali Plant sent the hot alkali solution to the heavy ash process for recovery; however, due to the presence of HCO3 in the alkali solution... - The high content of alkali leads to fluctuations in the concentration of hydrated chemical water in the hydration machine, resulting in larger and more viscous monohydrate crystals, frequent blockages, and severe scaling. Therefore, the hot alkali solution can only be sent to the sodium bicarbonate process for recycling.

[0007] The above analysis shows that major alkali plants have conducted extensive exploratory work on the recycling of hot alkali solution based on their own characteristics. However, the recycling process for heavy soda ash production has encountered problems such as poor crystallization quality, equipment scaling, and pipeline blockage. Therefore, it is of great significance to develop a new process for recycling hot alkali solution for heavy soda ash production. Successful development of the project will achieve energy conservation, emission reduction, and consumption reduction, reduce production costs, and promote the further development of the soda ash industry. Utility Model Content

[0008] The purpose of this invention is to address the shortcomings of existing technologies by proposing a device for preparing heavy soda ash based on hot alkaline solution.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a reaction tank, wherein two sets of pipes are arranged on one side of the reaction tank, and the two sets of pipes are respectively used to put in hot alkali solution and liquid alkali solution, and the reaction tank is used to react the hot alkali solution and liquid alkali solution to reduce the bicarbonate content in the hot alkali solution, and an ammonia stripping tower is arranged on one side of the reaction tank, and the ammonia stripping tower is connected to the reaction tank through a pipe, and a mixing liquid pump is provided on the pipe to transfer the hot alkali solution to the ammonia stripping tower.

[0010] As a further description of the above technical solution:

[0011] The ammonia stripping tower is equipped with a transmission pipe on one side, and a liquid alkali pump is installed on the transmission pipe for transmitting the ammonia stripping compound. One end of the transmission pipe on one side of the ammonia stripping tower is fixedly connected to a chemical water tank, and a heat exchanger is fixedly arranged on the transmission pipe for heating the ammonia stripping compound before it enters the chemical water tank to react with the chemical water.

[0012] As a further description of the above technical solution: a hydration machine is arranged on one side of the chemical water tank, and the hydration machine is equipped with a liquid phase hydration component and a solid phase hydration component for reacting soda ash to produce high-quality soda ash; a screw conveyor and a scraper are provided above the hydration machine for scraping and conveying soda ash.

[0013] As a further description of the above technical solution:

[0014] Below the hydration machine is a screw conveyor for transporting soda ash, and below the screw conveyor is a common heavy ash calcining furnace for calcining the soda ash fed by the screw conveyor. A cooling alkali is fixedly connected to one side of the common heavy ash calcining furnace for scraping off the calcined soda ash and sending it to the cooling alkali for cooling.

[0015] This utility model has the following beneficial effects:

[0016] By utilizing the excess hot alkali solution from the calcining furnace gas scrubbing system to produce heavy soda ash, the resource utilization of the hot alkali solution is realized, environmental pollution is reduced, and the company's soda ash production costs are lowered.

[0017] Sodium bicarbonate in hot alkaline solution is completely converted into sodium carbonate by heating the solution or adding liquid alkali. This avoids problems such as pipe blockage and equipment scaling caused by the relatively low solubility of sodium bicarbonate. The converted hot alkaline solution can be used for solid-phase hydration to prepare ordinary heavy ash, or for liquid-phase hydration to prepare high-quality heavy ash. The process can be flexibly adjusted according to market demand and actual production conditions.

[0018] 3. By adjusting the concentration of chemically combined water and hydration conditions, the crystallization of hydrated soda ash can be improved, the crystallization particle size can be increased, the water content and salt content of soda ash crystals can be reduced, the quality of heavy soda ash products can be improved, the steam consumption of the calcination process can be reduced, and the quality can be improved and the consumption reduced. Attached Figure Description

[0019] Figure 1 The flowchart is for an apparatus for preparing heavy soda ash based on hot alkaline solution proposed in this utility model.

[0020] Legend: 1. Reaction tank; 2. Hot alkali solution; 3. Liquid alkali; 4. Mixing liquid pump; 5. Ammonia stripping tower; 6. Liquid alkali pump; 7. Heat exchanger; 8. Chemical water tank; 12. Hydration machine; 13. Screw conveyor; 15. Ordinary heavy ash calcining furnace; 17. Cooling alkali. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The utility model will be further described in detail below with reference to the accompanying drawings.

[0023] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0024] Reference Figure 1 The present invention provides an embodiment of a device for preparing heavy soda ash based on hot alkali solution: a process for removing sodium bicarbonate by caustic soda reaction, hot alkali solution 2 is fed into reaction tank 1, and then liquid alkali 3 is added to react and reduce the bicarbonate content in hot alkali solution 2. Then, the blending liquid is sent to ammonia stripping tower 5 by blending liquid pump 4, and most of the free ammonia in hot alkali solution 2 is removed directly by heat exchanger 7 through ammonia stripping tower 5.

[0025] The solid-phase hydration process includes: hot alkali solution 2, after being distilled through ammonia stripping tower 5, is transferred to heat exchanger 7 via liquid alkali pump 6, cooled, and then fed into chemical water tank 8. It is then fed into hydration machine 12 where it undergoes a hydration reaction with light soda ash from the light ash process according to a specified ratio, generating monohydrate alkali crystals. These monohydrate crystals are then fed into ordinary heavy ash calcining furnace 15 via screw conveyor 13 and star feeder for heating and moisture removal. After cooling alkali 17, ordinary heavy soda ash is obtained. The concentration of chemical water used in the solid-phase hydration process is... The concentration is approximately 10-20 tt, which is relatively low. The concentration of the liquid phase hydrated chemical water is approximately 130-140 tt, of which the sodium bicarbonate content is approximately 7-8 tt. However, the sodium bicarbonate content in the hot alkali solution is approximately 20 tt, which is more than twice the sodium bicarbonate content in the liquid phase hydrated chemical water. Sending the hot alkali solution into the heavy ash process as chemical water can easily cause a large amount of crystal precipitation in the area near the heat exchange surface, affecting the crystallization quality of the monohydrate alkali, and may even cause blockages in the mother liquor tank, the bottom of the crystallizer, and pipelines.

[0026] The liquid-phase hydration process includes: hot alkali solution 2 after ammonia stripping is sent to a mother liquor tank via a liquid alkali pump 6; light soda ash is added to the mother liquor tank to prepare a liquid alkali 3 of a certain concentration as a hydration mother liquor; a certain water-alkali ratio is controlled; the mother liquor and light soda ash are sent to a hydration machine 12 for hydration reaction to generate monohydrate soda ash crystals; the monohydrate soda ash crystals are sent to a high-quality heavy ash calcining furnace via a screw conveyor and a star feeder for calcination; and then after cooling alkali 17, heavy soda ash is obtained. In theory, the crystallization temperature range of monohydrate soda ash is relatively large during the liquid-phase hydration process, but the temperature control and temperature distribution of the crystallizer cannot obtain stable monohydrate soda ash crystals within this temperature range. The temperature control of the crystallizer must ensure a fast reaction rate and a fast crystal growth rate, and also reduce the viscosity of the material in the crystallizer to avoid material adhesion and blockage of equipment pipes.

[0027] The process of removing sodium bicarbonate by heating and decomposition includes: hot alkaline solution 2 is fed into ammonia stripping tower 5, where sodium bicarbonate is directly decomposed by steam heating, reducing the HCO3- content in alkaline solution 3 and removing most of the free ammonia from the hot alkaline solution 2. The decomposed alkaline solution 3 is then sent to the solid-phase hydration system and liquid-phase hydration system in the hydration machine 12 to prepare ordinary heavy soda ash and high-quality heavy soda ash. The hot alkaline solution contains about 3 tt of free ammonia. If this free ammonia is directly fed into the heavy ash production system without treatment, some of the ammonia gas will eventually be discharged with the heavy ash tail gas. This will not only increase environmental risks but also waste ammonia and increase production costs. Therefore, the hot alkaline solution needs to be fed into the ammonia stripping tower before entering the crystallizer, where the free ammonia in the hot alkaline solution is purified by steam heating, ensuring that all free ammonia is recovered and reused while minimizing steam consumption.

[0028] The detailed implementation methods disclosed in this article omit the detailed descriptions of known functions and known components. In order to ensure the compatibility of the assemblies, the operating methods adopted are consistent with the pipe diameter parameters of the market.

[0029] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An apparatus for preparing heavy soda ash based on hot alkaline solution, characterized in that: include: The reaction tank (1) has two sets of pipes arranged on one side, and the two sets of pipes are used to put hot alkaline solution (2) and liquid alkali (3) into the reaction tank (1). The reaction tank (1) is used to react the hot alkaline solution (2) and liquid alkali (3) to reduce the bicarbonate content in the hot alkaline solution (2). An ammonia stripping tower (5) is arranged on one side of the reaction tank (1). The ammonia stripping tower (5) is connected to the reaction tank (1) through a pipe. A mixing liquid pump (4) is provided on the pipe to transfer the hot alkaline solution (2) to the ammonia stripping tower (5).

2. The apparatus for preparing heavy soda ash based on hot alkaline solution according to claim 1, characterized in that: The ammonia stripping tower (5) is provided with a transmission pipe on one side, and a liquid alkali pump (6) is provided on the transmission pipe for transmitting the ammonia stripping compound. One end of the transmission pipe on one side of the ammonia stripping tower (5) is fixedly connected to the chemical water tank (8), and a heat exchanger (7) is fixedly arranged on the transmission pipe for heating the ammonia stripping compound and then entering the chemical water tank (8) to react with the chemical water.

3. The apparatus for preparing heavy soda ash based on hot alkaline solution according to claim 2, characterized in that: A hydration machine (12) is arranged on one side of the chemical water tank (8), and the hydration machine (12) is equipped with a liquid phase hydration component and a solid phase hydration component, which are used to react soda ash to produce high-quality soda ash. Each of the hydration machines (12) is equipped with a screw conveyor (13) and a scraper for scraping and conveying soda ash.

4. The apparatus for preparing heavy soda ash based on hot alkaline solution according to claim 3, characterized in that: The hydration machine (12) is equipped with a screw conveyor (13) for transporting soda ash, and a common heavy ash calcining furnace (15) is provided below the screw conveyor (13) for calcining the soda ash introduced by the screw conveyor (13). A cooling alkali (17) is fixedly connected to one side of the common heavy ash calcining furnace (15) for scraping off the calcined soda ash and sending it into the cooling alkali (17) for cooling.

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