CN115594201A - Production method of heavy soda ash - Google Patents
Production method of heavy soda ash Download PDFInfo
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- CN115594201A CN115594201A CN202211588229.2A CN202211588229A CN115594201A CN 115594201 A CN115594201 A CN 115594201A CN 202211588229 A CN202211588229 A CN 202211588229A CN 115594201 A CN115594201 A CN 115594201A
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- sodium bicarbonate
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- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 title claims abstract description 201
- 235000017550 sodium carbonate Nutrition 0.000 title claims abstract description 71
- 229910000029 sodium carbonate Inorganic materials 0.000 title claims abstract description 71
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 34
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 155
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims abstract description 104
- 239000007788 liquid Substances 0.000 claims abstract description 104
- 238000000034 method Methods 0.000 claims abstract description 54
- 235000017557 sodium bicarbonate Nutrition 0.000 claims abstract description 52
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims abstract description 52
- 239000000725 suspension Substances 0.000 claims abstract description 44
- 238000010438 heat treatment Methods 0.000 claims abstract description 41
- 230000008569 process Effects 0.000 claims abstract description 24
- 238000001354 calcination Methods 0.000 claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000013078 crystal Substances 0.000 claims abstract description 9
- MQRJBSHKWOFOGF-UHFFFAOYSA-L disodium;carbonate;hydrate Chemical compound O.[Na+].[Na+].[O-]C([O-])=O MQRJBSHKWOFOGF-UHFFFAOYSA-L 0.000 claims abstract description 9
- 238000000926 separation method Methods 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000003513 alkali Substances 0.000 claims description 82
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 8
- 239000008234 soft water Substances 0.000 claims description 6
- 239000002699 waste material Substances 0.000 claims description 6
- -1 soda ash monohydrate Chemical class 0.000 claims description 2
- 238000011112 process operation Methods 0.000 abstract description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 33
- 239000000243 solution Substances 0.000 description 20
- 229910021529 ammonia Inorganic materials 0.000 description 15
- 230000002829 reductive effect Effects 0.000 description 14
- 239000000047 product Substances 0.000 description 11
- 229940001593 sodium carbonate Drugs 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 238000002425 crystallisation Methods 0.000 description 7
- 230000008025 crystallization Effects 0.000 description 7
- 238000007906 compression Methods 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 238000004090 dissolution Methods 0.000 description 4
- 239000000428 dust Substances 0.000 description 4
- 230000036571 hydration Effects 0.000 description 4
- 238000006703 hydration reaction Methods 0.000 description 4
- 150000004682 monohydrates Chemical class 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- 239000012267 brine Substances 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000005086 pumping Methods 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 3
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 2
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 229910001425 magnesium ion Inorganic materials 0.000 description 2
- 239000012452 mother liquor Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000004904 shortening Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 206010039509 Scab Diseases 0.000 description 1
- 238000009621 Solvay process Methods 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009993 causticizing Methods 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000010951 particle size reduction Methods 0.000 description 1
- 229940076133 sodium carbonate monohydrate Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005292 vacuum distillation Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D7/00—Carbonates of sodium, potassium or alkali metals in general
- C01D7/12—Preparation of carbonates from bicarbonates or bicarbonate-containing product
- C01D7/126—Multi-step processes, e.g. from trona to soda ash
Abstract
The invention discloses a production method of heavy soda ash, which comprises the steps of conveying crude heavy soda to a soda dissolving barrel, mixing the crude heavy soda with soda dissolving liquid to prepare sodium bicarbonate suspension; sending the sodium bicarbonate suspension into a decomposition tower, heating by using low-pressure steam to obtain a decomposition liquid containing sodium carbonate, and controlling the decomposition rate of the sodium bicarbonate to be more than 94%; feeding the decomposition liquid into a crystallizer, adding light soda ash to adjust to obtain a saturated sodium carbonate solution, adding water to form a monohydrate sodium carbonate suspension, and performing centrifugal separation to obtain monohydrate sodium carbonate; and (3) conveying the soda ash into a calcining furnace, and calcining to remove crystal water to obtain the heavy soda ash. The invention can reduce the consumption of light soda ash, reduce the investment on equipment, simplify the process flow, reduce the difficulty of process operation and reduce the production cost.
Description
Technical Field
The invention relates to the field of heavy soda ash production, in particular to a method for producing heavy soda ash through wet decomposition of heavy soda.
Background
The traditional production method of the heavy soda ash mainly comprises a solid phase hydration method and a liquid phase hydration method, and no matter which method is adopted, the light soda ash is required to be used as a raw material. The present production method of light soda needs to firstly heat and decompose the intermediate product coarse heavy soda, the main component of the coarse heavy soda is sodium bicarbonate, the device for heating and decomposing the coarse heavy soda is a calcining furnace, and the process flow is as follows: the coarse and heavy soda is conveyed by a belt conveyor, the input amount of the coarse and heavy soda is controlled by a feeder, the coarse and heavy soda is mixed with the circulating returned soda at a furnace end and then is conveyed into a calcining furnace, the mixture is decomposed and dried in the furnace to generate light soda, the light soda is taken out from the furnace tail and then is conveyed by a bucket elevator and an embedded scraper, one part of the light soda is returned to the furnace, one part of the light soda is cooled and then is packaged into a light soda product, and the other part of the light soda product is conveyed to a heavy soda process as a raw material for producing heavy soda.
The production method of producing the light calcined soda by utilizing the calcining furnace to thermally decompose the crude heavy calcined soda is called as a heavy soda dry decomposition method, the light calcined soda obtained by the production method is used for producing the heavy calcined soda by a solid-phase hydration method or a liquid-phase hydration method, the light calcined soda and soft water are hydrated to produce the sodium carbonate monohydrate, and the heavy calcined soda product is obtained by centrifugation and calcination.
The traditional production method of the soda ash has the following problems:
(1) The finished product of light soda ash is used as a raw material, so that the process flow is long and the cost is high. (2) The method has the advantages of multiple mechanical devices, large occupied area, high investment cost and complex process operation. (3) The dry decomposing method of the heavy alkali has high requirements on the quality of the crude heavy alkali, and when the crystallization of the crude heavy alkali is poor, the working condition of a calcining furnace is deteriorated, and the capability is reduced. And (4) alkali dust flies on site, and the working condition is poor. (5) The field transmission equipment is more, the noise is large, and the equipment failure rate is high.
The decomposition of the crude heavy alkali is carried out by a wet decomposition method of heavy alkali in addition to a dry decomposition method of heavy alkali. The process flow is as follows: the crude heavy alkali enters an alkali dissolving barrel through a feeder to be dissolved to prepare sodium bicarbonate suspension, the alkali dissolving liquid is generally hot waste weak liquor (high-temperature waste water remained after ammonia-containing waste water is heated by steam to evaporate ammonia), the sodium bicarbonate suspension is pumped into the upper part of a decomposition tower to be in countercurrent contact with the steam to be heated and decomposed to generate sodium carbonate, the decomposed solution is called decomposition liquid, and the decomposition liquid is pumped to a causticizing method for preparing caustic soda or producing sodium bicarbonate but cannot be used for producing the heavy sodium carbonate. In the prior art, the heavy alkali wet decomposition is generally carried out under the normal pressure condition, the wet decomposition temperature is controlled to be 100 ℃, and under the condition, the decomposition rate can reach 91.5 percent theoretically, but in the actual industrial production, the decomposition rate can only reach about 85 percent due to the existence of reverse reaction, and a long balance time is needed to seek a higher decomposition rate, so the method is difficult to realize in the actual production of the prior art. The main reason why the decomposition liquid can not be used for producing the heavy soda ash is that the decomposition liquid has high content of sodium bicarbonate, and the soda ash can be deteriorated when used as mother liquid to produce soda ash monohydrate, so that the inside of a crystallizer is scabbed, and the service time of equipment is shortened; but also causes the particle size reduction of the heavy soda ash and influences the product quality.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for producing heavy soda ash, which utilizes wet heavy soda decomposition liquid as mother liquid for producing the heavy soda ash, reduces the consumption of light soda ash, reduces equipment investment, simplifies process flow, reduces process operation difficulty and reduces production cost.
In order to solve the technical problem, the invention comprises the following steps:
(1) Conveying the crude heavy alkali to an alkali dissolving barrel, and mixing the crude heavy alkali with an alkali dissolving liquid to prepare a sodium bicarbonate suspension;
(2) Sending the sodium bicarbonate suspension into a decomposition tower, heating by using low-pressure steam to obtain a decomposition liquid containing sodium carbonate, and controlling the decomposition rate of the sodium bicarbonate to be more than 94%; ammonia and CO produced by decomposition 2 The mixed gas of the steam and the water is overflowed from the top of the tower;
(3) Sending the decomposition liquid to a crystallizer, adding light soda ash to adjust to obtain a saturated sodium carbonate solution, adding water to form a monohydrate sodium carbonate suspension, and performing centrifugal separation to obtain monohydrate sodium carbonate;
(4) And (3) conveying the monohydrate sodium carbonate into a calcining furnace, and calcining to remove crystal water to obtain the dense soda ash.
Preferably, in the step (1), the solid-to-liquid ratio of the sodium bicarbonate suspension is controlled to be 35% -50%; the chemical alkali liquor is one or more of hot alkali liquor, hot waste weak liquor and soft water.
Preferably, in the step (2), the pressure of the top of the decomposition tower is controlled to be 0.2-0.3Mpa; the temperature of the effluent of the decomposition liquid is controlled between 120 and 150 ℃.
Preferably, in the step (2), the heating of the decomposition liquid by using low-pressure steam is one of direct heating and indirect heating, or a combination thereof.
More preferably, in the step (2), when the method for heating the sodium bicarbonate suspension by using low-pressure steam is direct heating, the low-pressure steam is introduced into the bottom of the decomposition tower, so that the steam and the decomposition liquid directly contact in a countercurrent manner.
More preferably, in the step (2), when the method for heating the sodium bicarbonate suspension by using low-pressure steam is indirect heating, a set of effluent circulation pipeline is additionally arranged at the bottom of the decomposition tower, a circulation pump and a heat exchanger are arranged on the effluent circulation pipeline, the low-pressure steam is used for indirectly exchanging heat with the decomposition liquid in the heat exchanger, the decomposition liquid after being heated returns to the bottom of the decomposition tower, and the effluent amount and the circulation amount of the decomposition tower are controlled to be 1.2-1.5.
More preferably, in the step (2), when the method for heating the sodium bicarbonate suspension by using the low-pressure steam is a combination of direct heating and indirect heating, the low-pressure steam is firstly introduced into the bottom of the decomposition tower to be directly heated at the beginning of opening the tower, so that the decomposition liquid is quickly heated, after the temperature of the decomposition liquid is increased to a control range, the introduction of the steam into the decomposition tower is stopped, and the method for heating the sodium bicarbonate suspension is changed into the indirect heating method.
Preferably, the decomposition liquid obtained in the step (2) is added with caustic soda solution to improve the decomposition rate of sodium bicarbonate in the decomposition liquid to more than 98%, and then the decomposition liquid is sent to the step (3) to produce the monohydrate caustic soda.
After the technical scheme is adopted, the invention has the beneficial effects that:
(1) The process method of the invention mainly uses the crude and heavy soda as the raw material to produce the heavy soda, and compared with the traditional production method of the heavy soda, the process method saves one-time calcining process, greatly reduces the consumption of the light soda and reduces the production cost of the heavy soda.
(2) Compared with a heavy soda wet decomposition process, the temperature of the decomposition liquid is further improved by improving the internal pressure of the decomposition tower, the effects of shortening the reaction time and inhibiting the occurrence of reverse reaction are achieved, the decomposition rate of the decomposition liquid is improved to more than 94 percent, and the problems that the crystallization of monohydrate soda and the quality of products are influenced when the decomposition liquid is used as mother liquid to produce heavy soda ash are solved.
(3) Compared with the traditional production method of the heavy soda ash, the process method provided by the invention also has the following advantages: 1) Saves one-time calcining process, reduces the dosage of the light soda ash, simplifies the process flow and reduces the production cost. 2) Mechanical equipment and occupied area are reduced, equipment investment is reduced, and operation difficulty is reduced. 3) The requirement on the quality of the crude heavy alkali is low, and even slurry-shaped crude heavy alkali does not influence the capacity of equipment. 4) Alkali dust does not exist in the production field, and the operation condition is improved. 5) The field transmission equipment is greatly reduced, and the equipment failure rate is reduced.
Drawings
The invention is described in further detail below with reference to the following figures and detailed description:
FIG. 1 is a process flow diagram of a process for producing heavy soda ash according to the present invention;
in the figure: 1. the device comprises a first alkali dissolving barrel 2, a decomposition tower 3, a heat exchanger 4, a crystallizer 5, a centrifuge 6, a calcining furnace 7 and a second alkali dissolving barrel.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, the apparatus employed in the present invention is: the first alkali dissolving barrel 1 is connected to the top of the decomposition tower 2 through a liquid inlet pipeline, a liquid inlet pump is arranged on the liquid inlet pipeline, a low-pressure steam inlet pipeline is arranged at the bottom of the decomposition tower, a liquid outlet pipeline is connected to the second alkali dissolving barrel 7, the second alkali dissolving barrel 7 is connected to the crystallizer 4 through a pipeline and a pump, and the rear part of the crystallizer 4 is sequentially connected with the centrifuge 5 and the calcining furnace 6; the bottom of the decomposition tower is provided with a set of liquid outlet circulation pipeline, and the circulation pipeline is provided with a circulation pump and a heat exchanger 3.
The principle of the invention is as follows: the sodium bicarbonate suspension is decomposed by the wet decomposition tower 2 to generate sodium carbonate decomposition liquid, and then the sodium carbonate decomposition liquid is used as mother liquor to produce the heavy soda ash. In the existing process of wet decomposition of heavy soda, a normal pressure distillation method is conventionally adopted, the decomposition rate of a decomposition liquid is only about 85 percent, and the difficulty of producing the heavy soda by using the decomposition liquid lies in that: the decomposition liquid contains sodium bicarbonate crystals, so that the sodium bicarbonate crystals are deteriorated to cause scabbing inside the crystallizer, the granularity of the heavy sodium carbonate is reduced, and the product quality is influenced. In order to solve the problems, the decomposition rate of the decomposition solution is required to be increased to more than 94%, the invention adopts a pressure distillation method to increase the internal pressure of the decomposition tower and further increase the temperature of the decomposition solution, thereby not only increasing the decomposition rate, but also shortening the reaction time, and the specific flow is as follows:
(1) Alkali dissolution: conveying the crude heavy alkali to a first alkali dissolving barrel 1, mixing with an alkali dissolving liquid to prepare a sodium bicarbonate suspension, and controlling the solid-to-liquid ratio of the suspension to be 35-50%. The solid content in the suspension is not easy to control too high, and when the solid-to-liquid ratio exceeds 60%, alkali is accumulated in the conveying pipeline to block the pipeline.
The alkali dissolving liquid can adopt one or the combination of hot alkali liquid, hot waste thin liquid and soft water, and the hot alkali liquid is preferred.
CO is generated after the decomposition of the crude heavy alkali 2 The mixed gas of ammonia and water vapor, called furnace gas, is passed through cyclone separator to separate alkali dust, and then passed through the processes of washing distilled mother liquor and soft water, and feeding them into compression process. In order to recover the alkaline dust in the furnace gas, the furnace gas is circularly washed by soft water or hot waste weak liquor to generate hot alkaline liquor, and after the furnace gas is washed, the hot alkaline liquor is sent to a brine refining process for removing magnesium from crude brine. The hot waste weak liquor refers to high-temperature waste water remained after ammonia is evaporated from ammonia-containing waste water through steam heating.
In the traditional ammonia-soda process, hot alkali liquor is used as a refining agent to remove magnesium ions in crude brine. In recent years, with the improvement of the quality of the raw salt, the content of magnesium ions in the crude salt water is reduced, the usage amount of the hot alkali liquor is reduced, and the problem of excessive hot alkali liquor is caused. In the invention, the hot alkali liquefaction coarse heavy alkali is adopted as a raw material for producing the heavy soda ash, so that the problem of excessive hot alkali liquor can be solved, the alkali and heat in the hot alkali liquor can be recovered, the use amounts of the coarse heavy alkali and low-pressure steam are reduced, and the production cost is reduced.
(2) Decomposing heavy alkali: pumping the sodium bicarbonate suspension into a decomposition tower 2 by a pump, heating the sodium bicarbonate suspension by low-pressure steam to perform decomposition reaction on the sodium bicarbonate to produce sodium carbonate, wherein the solution obtained after decomposition is called decomposition liquid, and ammonia gas and CO generated by decomposition 2 And the mixed gas of the ammonia and the water vapor overflows from the tower top, and is sent to a compression process after ammonia is washed and purified. The tower top pressure of the decomposition tower is controlled at 0.2-0.3Mpa, the temperature of the effluent of decomposition liquid is controlled at 120-150 ℃, and the effluent amount is controlled at 40-50m 3 /h。
Methods of low pressure steam heating the decomposition liquid include direct heating, indirect heating, or a combination thereof. When the direct heating method is adopted, low-pressure steam is introduced to the bottom of the decomposition tower to make the steam and the decomposition liquid in countercurrent contact, so that the temperature of the decomposition liquid is increased.
When an indirect heating method is adopted, a set of effluent circulation flow and a heat exchanger 3 are additionally arranged at the bottom of the decomposition tower 2, low-pressure steam is utilized to indirectly exchange heat with decomposition liquid in the heat exchanger 3, the temperature of the decomposition liquid is increased, and the decomposition liquid after being heated returns to the bottom of the decomposition tower 2. The liquid outlet amount and circulation amount of the decomposing tower 2 are controlled by 1.2-1.5.
Compared with indirect heating, the direct heating has the advantages of high heat exchange efficiency, steam saving, high temperature raising speed and shortened reaction time, and has the defects of diluting the decomposition liquid and reducing the concentration of alkali liquor.
When the combination of direct heating and indirect heating is adopted, low-pressure steam is firstly introduced into the bottom of the decomposition tower 2 at the initial stage of tower opening to quickly raise the temperature of the decomposition liquid, after the temperature of the decomposition liquid is raised to a control range, the introduction of the steam into the decomposition tower 2 is stopped, and the indirect heating mode is adopted to heat the decomposition liquid. By adopting the heating mode, the reaction time can be shortened on the premise of not diluting the decomposition liquid.
(3) And (3) crystallization separation: the decomposed liquid is sent to a crystallizer 4, a proper amount of light soda ash is added to prepare saturated sodium carbonate solution, a soda water reaction is carried out to generate a soda water suspension, and then a centrifuge 5 is used for separating the soda water.
(4) Conveying the monohydrate sodium carbonate into a calcining furnace 6 by a screw, and calcining to remove crystal water to obtain the dense soda ash.
In order to further improve the monohydrate caustic soda crystallization and increase the particle size of the heavy soda ash, a proper amount of caustic soda solution is added before the decomposition liquid enters the crystallizer 4, the decomposition rate of the sodium bicarbonate in the decomposition liquid is increased to more than 98 percent, the solution is called as a refined decomposition liquid, and the refined decomposition liquid is sent to the crystallizer 4 to produce the monohydrate soda.
Example 1
A method for producing heavy soda ash comprises the following specific flow:
(1) Alkali dissolution: conveying the crude heavy alkali to a first alkali dissolving barrel 1, mixing with alkali dissolving liquid to prepare sodium bicarbonate suspension, wherein the solid-liquid ratio of the suspension is controlled to be 50%.
(2) Decomposing heavy alkali: delivering sodium bicarbonate suspension into decomposition tower 2 with pump, heating by direct heat exchange method to decompose sodium bicarbonate to produce sodium carbonate, decomposing the solution to obtain decomposition solution, and decomposing to obtain ammonia gas and CO 2 And the mixed gas of the ammonia and the water vapor overflows from the tower top, and is sent to a compression process after ammonia is washed and purified. The pressure at the top of the decomposing tower 2 is controlled to be 0.3Mpa, the temperature of the discharged liquid is controlled to be 150 DEG CThe liquid output is controlled to be 50m when the production scale of the heavy soda ash is 300 tons/day 3 And h, controlling the decomposition rate of the sodium bicarbonate to be more than 94%.
(3) And (3) crystallization separation: the decomposed liquid is sent to a crystallizer 4, a proper amount of light soda ash is added to prepare a saturated sodium carbonate solution, a water-alkali reaction is carried out to generate a water-alkali suspension, and then the water-alkali is separated out by a centrifuge 5.
(4) Conveying the soda water into a calcining furnace 6 through a screw, and calcining to remove crystal water to obtain the heavy soda ash.
Example 2
A method for producing dense soda ash comprises the following specific steps:
(1) Alkali dissolution: conveying the crude heavy alkali to a first alkali dissolving barrel 1, mixing with alkali dissolving liquid to prepare sodium bicarbonate suspension, wherein the solid-liquid ratio of the suspension is controlled to be 35%.
(2) Decomposing heavy alkali: pumping the sodium bicarbonate suspension into a decomposition tower 2 by a pump, heating the sodium bicarbonate suspension by using an indirect heat exchange method to cause the sodium bicarbonate to generate decomposition reaction to produce sodium carbonate, wherein the solution obtained after decomposition is called decomposition liquid, and ammonia gas and CO generated by decomposition 2 And the mixed gas of the ammonia and the water vapor overflows from the tower top, and is sent to a compression process after ammonia is washed and purified. The pressure at the top of the decomposing tower 2 is controlled to be 0.2Mpa, the effluent temperature is controlled to be 120 ℃, and the effluent amount is controlled to be 40m when the production scale of the heavy soda ash is 240 tons/day 3 The liquid outlet amount and the circulating amount are controlled to be 1.5, and the decomposition rate of the sodium bicarbonate is controlled to be more than 94%.
(3) And (3) crystallization separation: the decomposed liquid is sent to a crystallizer 4, a proper amount of light soda ash is added to prepare a saturated sodium carbonate solution, a water-alkali reaction is carried out to generate a water-alkali suspension, and then the water-alkali is separated out by a centrifuge 5.
(4) Conveying the soda water into a calcining furnace 6 through a screw, and calcining to remove crystal water to obtain the heavy soda ash.
Example 3
A method for producing heavy soda ash comprises the following specific flow:
(1) Alkali dissolution: the crude heavy alkali is conveyed to a first alkali dissolving barrel 1 and mixed with alkali dissolving liquid to prepare sodium bicarbonate suspension, and the solid-liquid ratio of the suspension is controlled to be 40%.
(2) Decomposing heavy alkali: pumping sodium bicarbonate suspension into a decomposition tower 2 by a pump, heating the sodium bicarbonate suspension by using a combined heat exchange method, introducing low-pressure steam into the bottom of the decomposition tower 2 at the initial stage of opening the tower, stopping introducing the low-pressure steam into the decomposition tower 2 when the temperature of the decomposition liquid rises to 130 ℃, heating the decomposition liquid by using an indirect heating mode to perform decomposition reaction on the sodium bicarbonate to produce sodium carbonate, wherein the solution obtained after decomposition is called decomposition liquid, and ammonia and CO generated by decomposition 2 And the mixed gas of the ammonia and the water vapor overflows from the tower top, and is sent to a compression process after ammonia is washed and purified. The pressure at the top of the decomposing tower 2 is controlled to be 0.25Mpa, the effluent temperature is controlled to be 130 ℃, and the effluent amount is controlled to be 45m when the heavy soda production scale is 270 tons/day 3 The liquid outlet amount and the circulating amount are controlled to be 1.2, and the decomposition rate of the sodium bicarbonate is controlled to be more than 94%.
(3) And (3) crystallization separation: the decomposed liquid is sent to a crystallizer 4, a proper amount of light soda ash is added to prepare a saturated sodium carbonate solution, a water-alkali reaction is carried out to generate a water-alkali suspension, and then the water-alkali is separated out by a centrifuge 5.
(4) Conveying the soda water into a calcining furnace 6 through a screw, and calcining to remove crystal water to obtain the heavy soda ash.
Example 4
The difference from the embodiment 2 is that a second alkali dissolving barrel 7 is added in the heavy alkali decomposition process, the decomposition liquid is firstly sent to the second alkali dissolving barrel 7, the caustic soda solution is added, the sodium bicarbonate suspension decomposition rate is improved to more than 98 percent, the solution is called as a fine decomposition liquid, the fine decomposition liquid is sent to a crystallizer 4, and the rest operations are the same as the embodiment 2.
To better demonstrate the process of the present invention, 3 comparative examples were made, with example 2 as a control. The 4 examples and 3 comparative examples are subjected to tracking detection, and specific detection results are shown in table 1 below.
Comparative example 1
The same operation as in example 2 was carried out except that the effluent temperature of the decomposition liquid was controlled at 160 ℃.
Comparative example 2
The operation was the same as in example 2 except that the top pressure of the decomposition column 2 was controlled to 0.35 MPa.
Comparative example 3
The difference from the example 2 is that one decomposing tower is added in the heavy alkali decomposing process, two-stage decomposition is arranged, the decomposing liquid is pumped into the second-stage decomposing tower after coming out from the first-stage decomposing tower, vacuum distillation is adopted in the second-stage decomposing tower, the negative pressure at the top of the second stage is controlled to be-20 Kpa, the steam is slightly introduced to the bottom of the decomposing tower, the liquid outlet temperature is controlled to be 120 ℃, the gas at the top of the second-stage decomposing tower is sent to the bottom of the first-stage decomposing tower, and the rest operations are the same as the example 2.
The following conclusions can be drawn from the running follow-up checks of examples 1 to 4 and comparative examples 1 to 3:
(1) From the detection results of the embodiments 1 to 3, the method for producing soda ash can make the wet decomposition rate of soda ash reach more than 95%, the production equipment of soda ash works well, and the quality of soda ash reaches the standard of class II superior products.
(2) From the test results of comparative example 1, when the decomposition liquid temperature was controlled at 160 ℃, the difference between the wet decomposition rate of heavy soda and the quality of heavy soda ash was small compared to example 2, but the steam consumption was increased by about 36 kg/ton soda.
(3) From the test results of comparative example 2, when the pressure at the top of the decomposition column 2 was controlled to 0.35Mpa, the wet decomposition rate of the heavy alkali was significantly reduced as compared with example 2, indicating that when the pressure control in the decomposition column 2 was too high, the reaction equilibrium of the decomposition of sodium bicarbonate was shifted to the left, and thus there was a technical risk.
(4) From the test results of comparative example 3, when the secondary decomposition was set, the steam consumption was reduced by 35 kg/ton alkali as compared with example 2, indicating that the heat in a part of the decomposed liquid can be recovered by the secondary decomposition tower, reducing the steam consumption; but the wet decomposition rate of the heavy soda is also obviously reduced to only 88.9 percent, which indicates that the reverse reaction of the decomposition of the sodium bicarbonate exists in the secondary decomposition tower, part of the sodium carbonate generates the sodium bicarbonate again, the production of the heavy soda is seriously influenced, and the quality of the heavy soda can only reach the standard of II-class qualified products.
(5) From the detection result of the example 4, the wet decomposition rate of the heavy soda can reach more than 98% by adding the caustic soda solution into the decomposition liquid, the product quality can be obviously improved, and the quality of the heavy soda reaches the standard of I-class products.
The above description is intended to be illustrative of the preferred embodiment of the present invention and should not be taken as limiting the invention, but rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Claims (8)
1. The production method of the heavy soda ash is characterized by comprising the following steps:
(1) Conveying the crude heavy alkali to an alkali dissolving barrel, and mixing the crude heavy alkali with an alkali dissolving liquid to prepare a sodium bicarbonate suspension;
(2) Sending the sodium bicarbonate suspension into a decomposition tower, heating the sodium bicarbonate suspension by using low-pressure steam to obtain a decomposition solution containing sodium carbonate, and controlling the decomposition rate of the sodium bicarbonate to be more than 94%;
(3) Sending the decomposition liquid to a crystallizer, adding light soda ash to adjust to obtain a saturated sodium carbonate solution, adding water to form a monohydrate sodium carbonate suspension, and performing centrifugal separation to obtain monohydrate sodium carbonate;
(4) And (3) conveying the soda ash into a calcining furnace, and calcining to remove crystal water to obtain the heavy soda ash.
2. The method for producing soda ash dense as claimed in claim 1, wherein in step (1), the solid-to-liquid ratio of the sodium bicarbonate suspension is controlled to be 35-50%; the alkali dissolving liquid is one or more of hot alkali liquid, hot waste dilute liquid and soft water.
3. The process for producing soda ash heavy as claimed in claim 1, wherein in said step (2), the top pressure of the decomposing tower is controlled to be 0.2-0.3Mpa; the temperature of the effluent of the decomposition liquid is controlled between 120 and 150 ℃.
4. The method for producing soda ash according to claim 1, wherein in the step (2), the sodium bicarbonate suspension is heated by using low-pressure steam in a manner of one or a combination of direct heating and indirect heating.
5. The process for producing soda ash according to claim 4, wherein in the step (2), when the sodium bicarbonate suspension is heated directly by using low-pressure steam, the low-pressure steam is introduced into the bottom of the decomposition tower to directly contact the decomposition solution in countercurrent.
6. The process for producing soda ash according to claim 4, wherein in the step (2), when the sodium bicarbonate suspension is heated indirectly by using low-pressure steam, a liquid outlet circulation line is additionally arranged at the bottom of the decomposition tower, a circulation pump and a heat exchanger are arranged on the circulation line, the low-pressure steam is used for indirectly exchanging heat with the decomposition liquid in the heat exchanger, the decomposition liquid after being heated returns to the bottom of the decomposition tower, and the liquid outlet amount and the circulation amount of the decomposition tower are controlled to be 1.
7. The method for producing soda ash according to claim 4, wherein in the step (2), when the method for heating the sodium bicarbonate suspension by using the low-pressure steam is a combination of direct heating and indirect heating, the low-pressure steam is firstly introduced into the bottom of the decomposition tower to be directly heated at the beginning of opening the tower, so that the decomposition liquid is rapidly heated, after the temperature of the decomposition liquid is raised to the control range, the introduction of the steam into the decomposition tower is stopped, and the method for heating the sodium bicarbonate suspension by using the indirect heating is changed.
8. The method for producing soda ash according to any one of claims 1 to 7, wherein the decomposition solution obtained in step (2) is added with caustic soda solution to increase the decomposition rate of sodium bicarbonate in the decomposition solution to more than 98%, and then the solution is sent to step (3) to produce soda ash monohydrate.
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|---|---|---|---|---|
| US4252781A (en) * | 1976-09-03 | 1981-02-24 | Central Glass Company, Limited | Preparation of sodium carbonate anhydride |
| JPH06102541B2 (en) * | 1985-01-30 | 1994-12-14 | ソルベイ（ソシエテ アノニム） | Method for producing heavy anhydrous sodium carbonate |
| CN1314310A (en) * | 2000-03-22 | 2001-09-26 | 喻中甫 | Method for producing low salt low potassium heavy mass sodium carbonate by one step process |
| CN101168443A (en) * | 2007-08-30 | 2008-04-30 | 内蒙古博源工程有限责任公司 | Method for producing low-salt heavy soda and system for producing the same |
| CN101708857A (en) * | 2009-11-20 | 2010-05-19 | 大连化工研究设计院 | Process for preparing low-salt heavy soda ash |
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2022
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| US4252781A (en) * | 1976-09-03 | 1981-02-24 | Central Glass Company, Limited | Preparation of sodium carbonate anhydride |
| JPH06102541B2 (en) * | 1985-01-30 | 1994-12-14 | ソルベイ（ソシエテ アノニム） | Method for producing heavy anhydrous sodium carbonate |
| CN1314310A (en) * | 2000-03-22 | 2001-09-26 | 喻中甫 | Method for producing low salt low potassium heavy mass sodium carbonate by one step process |
| CN101168443A (en) * | 2007-08-30 | 2008-04-30 | 内蒙古博源工程有限责任公司 | Method for producing low-salt heavy soda and system for producing the same |
| CN101708857A (en) * | 2009-11-20 | 2010-05-19 | 大连化工研究设计院 | Process for preparing low-salt heavy soda ash |
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Inventor after: Ma Chunxiao Inventor after: Wang Yulai Inventor after: Shi Hengliang Inventor after: Qiu Guoliang Inventor after: Wu Hong Inventor after: Wang Linlin Inventor after: Ren Guangqiu Inventor after: Li Chen Inventor after: Yu Hongwei Inventor after: Ding Keqi Inventor after: Zhang Junfeng Inventor before: Ma Chunxiao Inventor before: Wang Yulai Inventor before: Shi Hengliang Inventor before: Qiu Guoliang Inventor before: Wu Hong Inventor before: Wang Linlin Inventor before: Ren Guangqiu Inventor before: Li Chen Inventor before: Yu Hongwei Inventor before: Ding Keqi Inventor before: Zhang Junfeng |
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Application publication date: 20230113 |