CN108975355B - Device for improving baking soda granularity by pre-carbonization method and production method - Google Patents
Device for improving baking soda granularity by pre-carbonization method and production method Download PDFInfo
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- CN108975355B CN108975355B CN201811069898.2A CN201811069898A CN108975355B CN 108975355 B CN108975355 B CN 108975355B CN 201811069898 A CN201811069898 A CN 201811069898A CN 108975355 B CN108975355 B CN 108975355B
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- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 title claims abstract description 100
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 59
- 229910000030 sodium bicarbonate Inorganic materials 0.000 title claims abstract description 50
- 235000017557 sodium bicarbonate Nutrition 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000009656 pre-carbonization Methods 0.000 title claims abstract description 37
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 172
- 238000003763 carbonization Methods 0.000 claims abstract description 144
- 239000013078 crystal Substances 0.000 claims abstract description 96
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 86
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 86
- 239000002002 slurry Substances 0.000 claims abstract description 70
- 239000003513 alkali Substances 0.000 claims abstract description 59
- 238000004140 cleaning Methods 0.000 claims abstract description 55
- 239000007788 liquid Substances 0.000 claims abstract description 49
- 239000002562 thickening agent Substances 0.000 claims abstract description 14
- 238000004064 recycling Methods 0.000 claims abstract description 8
- 239000007789 gas Substances 0.000 claims description 53
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- 238000001035 drying Methods 0.000 claims description 13
- 238000002360 preparation method Methods 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 8
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 230000002950 deficient Effects 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 4
- 238000000746 purification Methods 0.000 claims description 3
- 238000004090 dissolution Methods 0.000 claims description 2
- 238000005070 sampling Methods 0.000 claims description 2
- 238000011112 process operation Methods 0.000 abstract description 2
- 239000002245 particle Substances 0.000 description 18
- 239000000243 solution Substances 0.000 description 14
- 230000008569 process Effects 0.000 description 13
- 238000005516 engineering process Methods 0.000 description 10
- 238000005406 washing Methods 0.000 description 9
- 239000011259 mixed solution Substances 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 5
- 238000004806 packaging method and process Methods 0.000 description 5
- 125000004122 cyclic group Chemical group 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 239000012452 mother liquor Substances 0.000 description 3
- 238000012216 screening Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-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
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000007605 air drying Methods 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
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
- C01D7/10—Preparation of bicarbonates from carbonates
-
- 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
- C01D7/38—Preparation in the form of granules, pieces or other shaped products
- C01D7/40—Influencing the crystallisation process
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The invention discloses a device for improving baking soda granularity by a pre-carbonization method and a production method thereof, comprising a carbonization tower, wherein the carbonization tower comprises a cleaning tower and an alkali making tower, the top of the carbonization tower is provided with a tail gas discharge port, the side surface of the top is provided with a feed inlet, and the side surface of the bottom is provided with a mixed gas inlet and a liquid outlet; the mixed gas inlets of the carbonization tower are connected with a mixed gas inlet pipeline, and the mixed gas inlet pipeline is formed by converging a low-concentration carbon dioxide pipeline and a high-concentration carbon dioxide pipeline; the liquid outlets of the carbonization tower are connected with carbonization liquid outlet pipelines, the carbonization liquid outlet pipelines are branched into carbonization crystal slurry pipelines and pre-carbonization crystal slurry pipelines, the carbonization crystal slurry pipelines are connected to the thickener through a crystal slurry pump, and the pre-carbonization crystal slurry pipelines are connected to the feed inlet of the carbonization tower through an alkaline pump; and the feed inlets of the carbonization towers are connected with alkali liquor dissolving pipelines, and the tail gas discharge ports are connected with tail gas emptying pipelines and carbonization tail gas recycling pipelines. The invention reduces the production cost, has simple process operation and is convenient for popularization.
Description
Technical Field
The invention relates to a device for improving granularity of a reaction crystallization product, in particular to a device for improving granularity of baking soda by a pre-carbonization method and a production method.
Background
Baking soda is one of important inorganic chemical products and is widely applied to various fields of chemical industry, light industry, medicine, textile, fine chemical industry and the like. The national yield of baking soda is large, the annual import and export amount reaches millions of tons, however, with the increase of the number of users and enterprises in special industries (such as feed industry and leather industry) on the market, the domestic single product can not meet the requirements. Compared with the baking soda mainly used in the food industry at present in China, the special industries have certain requirements on the granularity of baking soda products, so that the industrialized production of granular baking soda becomes a hot spot of close attention of a plurality of enterprises at present.
The research of granular baking soda by the prior patent technology mainly comprises a double decomposition method, a crystallizer method and a seed crystal adding method.
As disclosed in patent CN101696022a, a "process for producing food-grade baking soda by double decomposition" adopts a batch production process of small-scale, three-stage double decomposition reaction, during which vacuum belt filtration and washing are adopted for multiple times, the process is complex, and the product is easy to be polluted; in the patent CN101185484A, the technology of CN101696022A is optimized in the continuous control double decomposition food grade baking soda production process, continuous production is realized, double decomposition reaction of sodium chloride and ammonium bicarbonate is carried out in a first-stage stirrer, and products with various specifications of 20-300 meshes can be produced, however, in the subsequent separation and drying process, the energy consumption is excessive, and the production cost is higher.
The crystallizer method includes patent technology of CN1047839A of Solvin company and patent technology of CN 104402023B of I company. The Sorve company technology mainly adopts a process of externally adding a fluidized bed crystallizer, supersaturated solution grows around seed crystals in the production process, but the process needs to build a specific crystallizer, maintains a certain supersaturation degree of the solution, and has great difficulties in operation and industrialized popularization.
The technology of the company directly adopts a crystallizer method to replace a production device of a carbonization tower in the traditional sense, and the production technology is not reported at home and abroad, however, the whole technology has strict design requirements on the crystallizer, and has higher requirements on the skills of operators in the production process, so that the technology still needs a period of time for large-scale industrialized popularization.
The method for adding seed crystal is mainly represented by the patent technology of the application publication No. CN 104402023B of the company, and adopts the modes of adding seed crystal and returning a part of crystal slurry to the bottom of the carbonization tower after the carbonization reaction to carbonize again to produce granular baking soda.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a device and a production method for improving the granularity of baking soda by a pre-carbonization method, on the basis, the effective utilization of tail gas is realized, the production cost is reduced, the process operation is simple, the popularization is convenient, and the baking soda product with the granularity of 150-32 meshes is continuously prepared.
The aim of the invention can be achieved by the following technical scheme.
The device for improving the baking soda granularity by the pre-carbonization method comprises carbonization towers which are arranged in parallel, wherein the carbonization towers are divided into a cleaning tower and an alkali making tower according to different purposes, the top of each carbonization tower is provided with a tail gas discharge port, the side surface of the top is provided with a feed inlet, and the side surface of the bottom is provided with a mixing air inlet and a liquid outlet; the mixed gas inlet of each carbonization tower is connected with a mixed gas inlet pipeline, and the mixed gas inlet pipeline is formed by converging a low-concentration carbon dioxide pipeline and a high-concentration carbon dioxide pipeline; the liquid outlet of each carbonization tower is connected with a carbonization liquid outlet pipeline, the carbonization liquid outlet pipeline is branched into a carbonization crystal slurry pipeline and a pre-carbonization crystal slurry pipeline, the carbonization crystal slurry pipeline is connected to a thickener through a crystal slurry pump, the thickener is connected with a centrifugal drying system, and the pre-carbonization crystal slurry pipeline is connected to the feed inlet of each carbonization tower through an alkaline liquid pump; the feed inlet of every carbonization tower all is connected with the alkali lye pipeline that changes, and the tail gas discharge port of every carbonization tower all is connected with tail gas blowdown pipeline and carbonization tail gas cyclic utilization pipeline, carbonization tail gas cyclic utilization pipeline is connected to low concentration carbon dioxide pipeline.
The low-concentration carbon dioxide pipeline, the high-concentration carbon dioxide pipeline, the carbonization crystal slurry pipeline, the pre-carbonization crystal slurry pipeline, the alkali dissolving liquid pipeline, the tail gas emptying pipeline and the carbonization tail gas recycling pipeline are respectively provided with valves; when a certain carbonization tower is used as a cleaning tower, valves on a high-concentration carbon dioxide pipeline and a carbonization crystal slurry pipeline which are connected with the carbonization tower are closed; when a certain carbonization tower is used as an alkali production tower, valves on a low-concentration carbon dioxide pipeline and a pre-carbonization crystal slurry pipeline which are connected with the carbonization tower are closed.
The specification parameters of the carbonization towers are the same, the number of the cleaning towers and the number of the alkali production towers are determined according to actual production conditions, and the number of the cleaning towers is less than or equal to 50% of the total number of the carbonization towers.
The number of the carbonization towers is preferably four, wherein 1-2 cleaning towers and 2-3 alkali-making towers are preferred.
The concentration of carbon dioxide in the low-concentration carbon dioxide pipeline is 15% -35%, and the concentration of carbon dioxide in the high-concentration carbon dioxide pipeline is 45% -65%.
The aim of the invention can be achieved by the following technical scheme.
The invention relates to a production method for improving the granularity of baking soda products by a pre-carbonization method, which comprises the following steps:
(1) Delivering the chemical alkali solution obtained after raw material dissolution and purification to a part of feed inlets of carbonization towers serving as cleaning towers, carrying out pre-carbonization reaction with low-concentration carbon dioxide in the carbonization towers to obtain supersaturated solution at a corresponding temperature, continuing to prolong the reaction residence time, and regularly sampling and detecting liquid in the carbonization towers (cleaning towers) until crystals are generated in the carbonization towers, wherein the solid-liquid ratio is not more than 10%;
(2) Starting an alkaline pump, conveying pre-carbonized crystal slurry in a cleaning tower to a feed inlet of each side surface of the top of a carbonization tower serving as an alkaline tower, wherein the total liquid quantity returned is equal to the total quantity of crystal slurry flowing out of a liquid outlet of the cleaning tower, and further carrying out carbonization reaction with high-concentration carbon dioxide in the carbonization tower (alkaline tower);
(3) And (3) conveying carbonized crystal slurry flowing out of the bottom of the alkali-making tower to a thickener through a crystal slurry pump, and continuously conveying thickened sodium bicarbonate crystals to a centrifugal drying system to finally obtain finished sodium bicarbonate.
The concentration range of the low-concentration carbon dioxide in the step (1) is 15% -35%, the concentration is preferably 35% at the initial stage of driving, the concentration of the carbon dioxide is preferably 25% after the device is normally produced, and the solid-liquid ratio in the step (1) is preferably 5%.
The low-concentration carbon dioxide is prepared by high-concentration carbon dioxide and nitrogen in the initial stage of starting, and after the device is normally produced, the low-concentration carbon dioxide mainly adopts carbonized tail gas to assist a small amount of high-concentration carbon dioxide.
The high-concentration carbon dioxide in the step (2) is 45% -65% in concentration, and is prepared by mixing carbon dioxide gas with 90% in concentration from a pipe network with pipe network nitrogen.
The size parameters of the carbonization towers in the step (1) and the step (2) are the same, the carbonization towers are distinguished according to different roles of the carbonization towers in the production process, according to actual production conditions, part of the carbonization towers are selectively used as alkali-making towers, the rest part of carbonization towers are used as cleaning towers, and the cleaning towers and the alkali-making towers can be flexibly switched.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) Compared with the methods such as a crystallizer, the method has the advantages that the original carbonization process flow is not required to be changed, the operation is simple, and the granularity of the product can be increased; compared with the traditional carbonization tower production method, the tail gas of the carbonization tower can be further and effectively utilized, and meanwhile, the whole device can continuously and uninterruptedly run for a long period under the condition that mechanical equipment parts are not damaged. In the actual production process, the alkali preparation period of the carbonization tower is obviously improved, the production efficiency of the device is obviously improved, and the production cost is reduced by 30 percent compared with the cost before the improvement of a company.
(2) In the initial stage of starting, alkali liquor is pre-carbonized in a cleaning tower, so that the alkali liquor reacts with low-concentration carbon dioxide to form supersaturated solution at the production temperature, the residence time is prolonged continuously to generate a small amount of sodium bicarbonate crystal grains, and when the pre-carbonized crystal slurry is sent to an alkali preparation tower to contact with high-concentration carbon dioxide, solute preferentially grows around crystal seeds due to the small amount of crystal grains in the crystal slurry, the phenomenon of explosive nucleation in an effective control system is effectively controlled, and the granularity of the product is finally effectively increased.
(3) The invention combines the cleaning tower and the alkali-making tower, can take the cleaning and the production of the tower into account, skillfully solves the washing water of the cleaning tower, fundamentally solves the expansion problem of the mother liquor of the system, and greatly improves the annual production efficiency and the operating rate of the device.
(4) The invention can produce products with various specifications of 150-32 meshes, and the granularity of baking soda products is greatly improved; the maximum grain diameter of the produced product can reach 32 meshes, the mass content of the product of 60-120 meshes is 63%, and the mass percentage of the product of 60-32 meshes can reach 11%.
Drawings
FIG. 1 is a schematic diagram of an apparatus for increasing baking soda particle size by the pre-carbonization process of the present invention;
FIG. 2 is a graph showing the particle size distribution of a baking soda product produced by the process of CN 104402023B;
FIG. 3 is a particle size distribution plot of the baking soda product produced in example 1;
FIG. 4 is a particle size distribution plot of the baking soda product produced in example 2;
fig. 5 is a microscopic image of the baking soda product produced in example 1.
The device comprises a carbonization tower 1, a 2-chemical alkali liquor pipeline, a gas mixture inlet pipeline 3, a low-concentration carbon dioxide pipeline 4, a high-concentration carbon dioxide pipeline 5, a 6-carbonization liquid outlet pipeline, a 7-carbonization crystal slurry pipeline, a 8-pre-carbonization crystal slurry pipeline, a 9-alkali liquor pump, a 10-crystal slurry pump, a 11-centrifugal drying system, a 12-thickener, a 13-carbonization tail gas recycling pipeline, a 14-tail gas emptying pipeline and a 15 valve.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in fig. 1, the device for improving the granularity of baking soda by the pre-carbonization method comprises carbonization towers 1 which are arranged in parallel, wherein the carbonization towers 1 are divided into cleaning towers and alkali production towers according to different purposes, the specification parameters of the carbonization towers 1 are the same, the number of the cleaning towers and the alkali production towers is determined according to actual production conditions, and the number of the cleaning towers is less than or equal to 50% of the total number of the carbonization towers 1. The number of the carbonization towers 1 is preferably four, wherein 1-2 washing towers and 2-3 alkali-making towers are preferred, and fig. 1 is only one example, wherein 1-1 is a washing tower, and 1-2, 1-3 and 1-4 are alkali-making towers. The cleaning tower has the functions of cleaning the crystallization products adhered in the tower, fully utilizing carbonized tail gas, pre-carbonizing the cleaning liquid containing crystal slurry particles and low-concentration carbon dioxide again, and then evenly distributing the pre-carbonized cleaning liquid and low-concentration carbon dioxide to the subsequent alkali-making tower. The purpose of the alkali preparation tower is to carbonize the pre-carbonized liquid reacted in the cleaning tower and high-concentration carbon dioxide again to generate more solutes and grow around crystal slurry particles to obtain carbonized crystal slurry.
Every carbonization tower 1's top all is provided with the tail gas emission mouth, and the top side all is provided with the feed inlet, and the bottom side all is provided with mixing air inlet and liquid outlet. The mixed gas inlet of each carbonization tower 1 is connected with a mixed gas inlet pipeline 3, the mixed gas inlet pipeline 3 is formed by converging a low-concentration carbon dioxide pipeline 4 and a high-concentration carbon dioxide pipeline 5, the concentration of carbon dioxide in the low-concentration carbon dioxide pipeline 4 is 15% -35%, the tail gas in a carbonized tail gas recycling pipeline 13 is used for assisting in mixing a small amount of high-concentration carbon dioxide, the concentration of carbon dioxide in the high-concentration carbon dioxide pipeline is 45% -65%, and the mixed gas is prepared by mixing carbon dioxide gas with pipe network nitrogen, wherein the concentration of the carbon dioxide gas is about 90%.
The liquid outlet of each carbonization tower 1 is connected with a carbonization liquid outlet pipeline 6, the carbonization liquid outlet pipeline 6 is branched into a carbonization crystal slurry pipeline 7 and a pre-carbonization crystal slurry pipeline 8, the carbonization crystal slurry pipeline 7 is connected to a thickener 12 through a crystal slurry pump 10, the thickener 12 is connected with a centrifugal drying system 11, and the pre-carbonization crystal slurry pipeline 8 is connected to the feed inlet of each carbonization tower 1 through a lye pump 9. When a certain carbonization tower 1 is used as a cleaning tower, liquid coming out from the bottom of the carbonization tower 1 is called pre-carbonized crystal slurry, and the pre-carbonized crystal slurry is conveyed to a feed port on the top side of the carbonization tower 1 serving as an alkali making tower in a pressing way through an alkali pump 9. When a certain carbonization tower 1 is used as an alkali preparation tower, crystal slurry coming out of the bottom of the carbonization tower 1 is called carbonized crystal slurry, and is sent into a carbonized crystal slurry pipeline 7, and the carbonized crystal slurry is sent into a thickener 12 to be thickened through a crystal slurry pump 10, and then enters a centrifugal drying system 11, so that a finished product is finally prepared.
The feed inlet of every carbonization tower 1 all is connected with chemical alkali liquid pipeline 2, and the tail gas discharge mouth of every carbonization tower 1 all is connected with tail gas blowdown pipeline 14 and carbonization tail gas cyclic utilization pipeline 13, carbonization tail gas cyclic utilization pipeline 13 is connected to low concentration carbon dioxide pipeline 4. The low-concentration carbon dioxide pipeline 4, the high-concentration carbon dioxide pipeline 5, the carbonization crystal slurry pipeline 7, the pre-carbonization crystal slurry pipeline 8, the alkali lye pipeline 2, the tail gas emptying pipeline 14 and the carbonization tail gas recycling pipeline 13 are respectively provided with a valve 15. When the carbonization tower 1 is used as a cleaning tower, the valves 15 on the high-concentration carbon dioxide pipeline 5 and the carbonization crystal slurry pipeline 7 which are connected with the carbonization tower 1 are closed, and the valves 15 on the low-concentration carbon dioxide pipeline 4 and the pre-carbonization crystal slurry pipeline 8 which are connected with the carbonization tower 1 are opened. When a certain carbonization tower 1 is used as an alkali production tower, the valve 15 on the low-concentration carbon dioxide pipeline 4 and the pre-carbonization crystal slurry pipeline 8 which are connected with the carbonization tower 1 are closed, and the valve 15 on the high-concentration carbon dioxide pipeline 5 and the carbonization crystal slurry pipeline 7 which are connected with the carbonization tower 1 are opened.
The invention relates to a production method for improving the granularity of baking soda products by a pre-carbonization method, which comprises the following specific processes:
(1) At the beginning of starting, the chemical alkali solution obtained by dissolving and purifying the raw materials is sent to a feed inlet 18 of a carbonization tower 1 which is partially used as a cleaning tower, the pre-carbonization reaction is carried out in the carbonization towers 1 with low-concentration carbon dioxide to obtain supersaturated solution at the corresponding temperature, the reaction residence time is continued to be prolonged, and then the liquid in the carbonization towers 1 (cleaning towers) is sampled and detected at fixed time until a small amount of crystals are generated in the carbonization towers 1, wherein the solid-liquid ratio is not more than 10%, preferably 5%.
The raw materials are industrial sodium carbonate, and comprise industrial defective sodium carbonate and heavy ash fine powder. The defective sodium carbonate generally refers to a product in which any one of the indexes of chloride content, iron content or water insoluble content exceeds the national standard; heavy ash fines generally refer to products that pass through a physical screening oversize product, which meets the soda index requirements, but does not meet the standard in particle size.
The concentration of the low-concentration carbon dioxide ranges from 15% to 35%, the concentration is preferably 35% at the initial stage of driving, and the concentration of the carbon dioxide is preferably 25% after the device is normally produced. The low-concentration carbon dioxide is obtained after the high-concentration carbon dioxide and nitrogen are mixed and configured at the initial stage of starting, and in the normal operation process, the low-concentration carbon dioxide is mainly carbonized tail gas at the top of a carbonization tower 1 serving as an alkali-making tower, and a small amount of high-concentration carbon dioxide is assisted. The carbon dioxide concentration in the carbonized tail gas is detected and tested, so that the requirement of the pre-carbonization reaction on the gas concentration is met, the tail gas is recycled again, and the production cost is reduced.
The purification here preferably employs a clarifying tank and a microporous filter in sequence, and the clarified solution enters an alkali liquor storage tank and is then sent to the carbonization tower 1.
(2) After a small amount of crystals are generated in the cleaning tower, the alkaline pump 9 is started, pre-carbonized crystal slurry in the cleaning tower is conveyed to the feed inlets on the side surface of the top of the carbonization tower 1 serving as an alkali preparation tower, the total liquid quantity returned is equal to the total quantity of crystal slurry flowing out of the liquid outlet of the cleaning tower, and carbonization reaction is further carried out with high-concentration carbon dioxide in the carbonization tower (alkali preparation tower). When the pre-carbonized crystal slurry is contacted with high-concentration carbon dioxide in an alkali preparation tower, a small amount of crystal grains exist in the crystal slurry, solutes preferentially grow around the crystal seeds, the phenomenon of burst nucleation in the system is effectively controlled, and the granularity of the product is finally effectively increased.
The high-concentration carbon dioxide is prepared by mixing carbon dioxide gas with the concentration of about 90% from a pipe network with nitrogen in the pipe network.
The parameters such as the size of the carbonization tower 1 in the step (1) and the step (2) are the same, the carbonization tower 1 is distinguished according to different roles in the production process, according to actual production conditions, part of the carbonization tower is selectively used as an alkali production tower, the rest carbonization tower is used as a cleaning tower, the cleaning tower and the alkali production tower can be flexibly switched, the phenomenon that the tower is stopped for cleaning or the load is reduced for production due to expiration of the alkali production period in the traditional production process is avoided, the process can be adopted for realizing simultaneous cleaning and production of the tower, the washing water of the cleaning tower is skillfully solved, the problem of expansion of system mother liquor is fundamentally solved, and the annual production efficiency and the operating rate of the device are greatly improved. The control of the operation parameters in the invention is realized by adopting the control parameters in the existing baking soda production process.
(3) And delivering carbonized crystal slurry flowing out of the bottom of the alkali-making tower to a thickener 12 through a crystal slurry pump 10, and continuously delivering thickened sodium bicarbonate crystals to a centrifugal drying system 11 to finally obtain finished baking soda.
Comparative example 1
The prior CN 104402023B patent method is adopted for producing sodium bicarbonate, the average grain diameter of the sodium bicarbonate product produced by the carbonization tower device is 176.5 mu m, and the alkali production period of the carbonization tower is 120 hours.
Example 1
The invention relates to a production method for improving the granularity of baking soda products by a pre-carbonization method, which comprises the following specific processes:
(1) The method comprises the steps of dissolving and preparing a mixture of industrial defective sodium carbonate and heavy ash fine powder into a mixed solution with total alkalinity of 80-85tt, sequentially adopting a clarifying barrel and a microporous filter to purify the mixed solution so that the calcium and magnesium content in the solution is reduced to below 20ppm, storing the mixed solution into an alkali solution storage barrel to obtain chemical alkali solution, then conveying the chemical alkali solution to a feed inlet of a cleaning tower at the flow rate of 80-110m 3/h, carrying out pre-carbonization reaction with low-concentration carbon dioxide (20% -35%) in the cleaning tower to form a supersaturated solution at a corresponding temperature, and continuously prolonging the reaction residence time to enable a small amount of crystals to be generated in the mixed solution until the solid-to-liquid ratio reaches 5%. Wherein, the alkali dissolving liquid can be centrifugal mother liquid thrown out by the centrifugal machine in the step (3).
(2) The pre-carbonized crystal slurry flowing out from the liquid outlet at the bottom of the cleaning tower is returned to the feed inlets of the remaining three alkali-making towers at the flow rate of 80-110m 3/h under the action of the alkali pump 9, and is further carbonized with high-concentration carbon dioxide gas with the concentration of 45-65% in the carbonization tower (alkali-making tower).
(3) And (3) delivering carbonized crystal slurry flowing out of a liquid outlet of the alkali preparation tower to a thickener 12, continuously delivering thickened sodium bicarbonate crystals to a centrifugal machine for drying, delivering sodium bicarbonate after centrifugal drying to a high-temperature air dryer at 170-190 ℃ for about 10s for air drying, cooling by cold air, vibrating and screening, and packaging in a packaging workshop to obtain the yield of 7.5t/h, wherein the product index reaches the industry standard.
And (3) detecting: the quality content of the obtained baking soda product with the grain diameter of <120 meshes (125 μm) is more than 40%, the quality content of 80-120 meshes (125 μm < 180 μm) is more than 30%, and the quality content of the baking soda product with the grain diameter of less than 80 meshes (180 μm) is more than 10%.
Comparing fig. 2 and fig. 3, the prior CN104402023B patent method is adopted to produce sodium bicarbonate, the average particle size of sodium bicarbonate produced by the carbonization tower device is 176.5 μm, and the alkali production period of the carbonization tower is 120h. The baking soda is produced by the method, and the average grain diameter of the produced product is 180.2 mu m. However, as can be seen from the particle size distribution diagram, the product has a smaller percentage of particle size below 80 μm, i.e. the content of fine powder is small, which is convenient for packaging the product. Further, as can be seen from the microscope image 5, the appearance of the product was a rod-like crystal.
Example 2
The invention relates to a production method for improving the granularity of baking soda products by a pre-carbonization method, which comprises the following specific processes:
(1) Dissolving industrial defective sodium carbonate to prepare a mixed solution with total alkalinity of 80-85tt, and purifying the mixed solution by sequentially adopting a clarifying barrel and a microporous filter to reduce the calcium and magnesium content in the solution to below 20ppm to obtain chemical alkali liquor. The chemical alkali liquid adopted for dissolving the industrial defective sodium carbonate raw material comes from the centrifugal mother liquor thrown out by the centrifugal machine in the step (3)
The cleaning tower in the method of the embodiment 1 is switched into an alkali making tower to replace one of the three alkali making towers, and simultaneously the replaced alkali making tower is cleaned by chemical alkali liquid, and the purpose of cleaning and pre-carbonization is achieved because residual sodium bicarbonate crystals exist in the alkali making tower and low-concentration carbon dioxide adopted at the moment is directly carbonized tail gas (the concentration of the carbon dioxide is 15% -25%).
If four carbonization towers exist, the number of the cleaning towers is at most two according to actual production conditions, otherwise, the production efficiency is affected. The switching period of the washing tower and the alkali-making tower is generally 24 hours after the washing tower and the alkali-making tower are rotated for the first time according to actual production conditions, that is, the alkali-making tower replaced in step 1 of example 2 is used as the washing tower, the remaining alkali-making tower which is not switched all the time is replaced by the washing tower after 24 hours, and the subsequent operation and the like.
(2) The pre-carbonized crystal slurry with crystal particles is returned to other three alkali-making towers at the flow rate of 80-110m 3/h under the action of an alkali pump 9, so as to provide seed crystals for the alkali-making towers, prolong the reaction crystallization time and increase the granularity of the product. The carbonization reaction is further carried out in the alkali preparation tower with high-concentration carbon dioxide gas with the concentration of 45% -65%, and due to the existence of the seed crystal, solute preferentially grows around the seed crystal, and the granularity of the product is finally increased.
(3) And (3) delivering carbonized crystal slurry flowing out of a liquid outlet of the alkali preparation tower to a thickener 12, continuously delivering thickened sodium bicarbonate crystals to a centrifugal machine for drying, delivering sodium bicarbonate after centrifugal drying to a high-temperature air dryer at 170-190 ℃ for about 10s for air drying, cooling by cold air, vibrating and screening, and packaging in a packaging workshop to obtain the yield of 7.5t/h, wherein the product index reaches the industry standard.
And (3) detecting: the mass content of the obtained product is more than 74% of the mass content of 120 meshes (the particle size is more than 125 mu m), the mass content of 60-120 meshes (the particle size is more than 125 mu m and less than 250 mu m), and the mass content of 32-60 meshes (the particle size is more than or equal to 500 mu m) and more than 11%.
Comparing with fig. 3 and fig. 4, because of the accumulation of reaction time in the earlier-stage cleaning tower, a certain amount of sodium bicarbonate crystal slurry particles with larger particle size exist in the cleaning tower, the crystal slurry is used as seed crystals of the alkali making tower, and the product is larger than the average particle size in the example 1 by recrystallization carbonization reaction in the alkali making tower, and the mass percentage of the product with the particle size of more than 125 μm is more than 74%.
Although the present invention has been described in connection with the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, which are merely illustrative, but not restrictive, and many forms may be made by those having ordinary skill in the art, which fall within the protection of the present invention.
Claims (3)
1. The device for improving the granularity of baking soda by a pre-carbonization method comprises carbonization towers (1) which are arranged in parallel, and the carbonization towers (1) are divided into a cleaning tower and an alkali preparation tower according to different purposes; the top of each carbonization tower (1) is provided with a tail gas discharge port, the side surface of the top is provided with a feed inlet, and the side surface of the bottom is provided with a mixing air inlet and a liquid outlet; the mixed gas inlet of each carbonization tower (1) is connected with a mixed gas inlet pipeline (3), and the mixed gas inlet pipeline (3) is formed by converging a low-concentration carbon dioxide pipeline (4) and a high-concentration carbon dioxide pipeline (5); the liquid outlet of each carbonization tower (1) is connected with a carbonization liquid outlet pipeline (6), the carbonization liquid outlet pipeline (6) is branched into a carbonization crystal slurry pipeline (7) and a pre-carbonization crystal slurry pipeline (8), the carbonization crystal slurry pipeline (7) is connected to a thickener (12) through a crystal slurry pump (10), the thickener (12) is connected with a centrifugal drying system (11), and the pre-carbonization crystal slurry pipeline (8) is connected to the feed inlet of each carbonization tower (1) through an alkaline liquid pump (9); the feed inlet of each carbonization tower (1) is connected with an alkali dissolving liquid pipeline (2), the tail gas discharge outlet of each carbonization tower (1) is connected with a tail gas emptying pipeline (14) and a carbonization tail gas recycling pipeline (13), and the carbonization tail gas recycling pipeline (13) is connected to a low-concentration carbon dioxide pipeline (4); wherein the concentration of carbon dioxide in the low-concentration carbon dioxide pipeline (4) is 15-35%, and the concentration of carbon dioxide in the high-concentration carbon dioxide pipeline (5) is 45-65%;
The low-concentration carbon dioxide pipeline (4), the high-concentration carbon dioxide pipeline (5), the carbonization crystal slurry pipeline (7), the pre-carbonization crystal slurry pipeline (8), the alkali dissolving liquid pipeline (2), the tail gas emptying pipeline (14) and the carbonization tail gas recycling pipeline (13) are respectively provided with a valve (15); when a certain carbonization tower (1) is used as a cleaning tower, a high-concentration carbon dioxide pipeline (5) connected with the carbonization tower (1) and a valve (15) on a carbonization crystal slurry pipeline (7) are closed; when a certain carbonization tower (1) is used as an alkali preparation tower, a valve (15) on a low-concentration carbon dioxide pipeline (4) and a pre-carbonization crystal slurry pipeline (8) which are connected with the carbonization tower (1) are closed;
The specification parameters of the carbonization towers (1) are the same, the number of the cleaning towers and the alkali production towers is determined according to actual production conditions, and the number of the cleaning towers is less than or equal to 50% of the total number of the carbonization towers; four carbonization towers (1) are arranged, wherein, the number of the cleaning towers is 1-2, and the number of the alkali-making towers is 2-3.
2. A production method for improving the granularity of baking soda products by a pre-carbonization method based on the device for improving the granularity of the baking soda by the pre-carbonization method is characterized in that the adopted carbonization towers have the same size parameters, are distinguished according to different roles of the carbonization towers in the production process, selectively take part of the carbonization towers as an alkali production tower and the rest as a cleaning tower according to actual production conditions, and can flexibly switch between the cleaning tower and the alkali production tower; the method comprises the following steps:
(1) Delivering the chemical alkali solution obtained after raw material dissolution and purification to a part of feed inlets of carbonization towers serving as cleaning towers, carrying out pre-carbonization reaction with low-concentration carbon dioxide in the carbonization towers to obtain supersaturated solution at a corresponding temperature, continuing to prolong the reaction residence time, and regularly sampling and detecting liquid in the cleaning towers until crystals are generated in the carbonization towers, wherein the solid-liquid ratio is not more than 10%;
Wherein the raw material is industrial sodium carbonate and comprises industrial defective sodium carbonate and heavy ash fine powder; the concentration range of the low-concentration carbon dioxide is between 15% and 35%, the low-concentration carbon dioxide is prepared by high-concentration carbon dioxide and nitrogen in the initial stage of starting, and after the device is normally produced, the low-concentration carbon dioxide mainly adopts carbonized tail gas and is assisted by a small amount of high-concentration carbon dioxide;
(2) Starting an alkaline pump, conveying pre-carbonized crystal slurry in the cleaning tower to feed inlets on the side surface of the top of the carbonization tower serving as an alkaline tower, wherein the total liquid quantity returned is equal to the total quantity of crystal slurry flowing out of a liquid outlet of the cleaning tower, and carrying out carbonization reaction with high-concentration carbon dioxide in the alkaline tower; wherein the concentration of the high-concentration carbon dioxide is 45% -65%, and the high-concentration carbon dioxide is prepared by mixing carbon dioxide gas with 90% from a pipe network with nitrogen in the pipe network;
(3) And (3) conveying carbonized crystal slurry flowing out of the bottom of the alkali-making tower to a thickener through a crystal slurry pump, and continuously conveying thickened sodium bicarbonate crystals to a centrifugal drying system to finally obtain finished sodium bicarbonate.
3. The method for producing the sodium bicarbonate product according to claim 2, wherein the low concentration carbon dioxide in the step (1) is 35% in initial stage of start-up, the carbon dioxide concentration after normal production of the apparatus is 25%, and the solid-to-liquid ratio in the step (1) is 5%.
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| CN112694105B (en) * | 2021-01-13 | 2023-11-17 | 河南中源化学股份有限公司 | High-efficiency carbonization reaction system |
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| CN209567818U (en) * | 2018-09-13 | 2019-11-01 | 天津渤化永利化工股份有限公司 | A kind of pre- carbonizatin method improves the device of sodium bicarbonate granularity |
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| CN209567818U (en) * | 2018-09-13 | 2019-11-01 | 天津渤化永利化工股份有限公司 | A kind of pre- carbonizatin method improves the device of sodium bicarbonate granularity |
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