Phosphoric acid and gypsum production circulation system

Abstract

The utility model provides a phosphoric acid and gypsum production circulating system, which is characterized in that the circulating system comprises a desulfurizing tower, a slurry delivery pump, a gypsum filter and an acidolysis reactor which are sequentially connected through a pipeline, the acidolysis reactor is also in loop connection with the desulfurizing tower through a pipeline, and after the system is used, the acidolysis reactor is connected with the desulfurizing tower through a pipeline. The calcium-containing acidolysis solution generated by reaction of phosphoric acid and phosphorite can be used as a desulfurizing agent, calcium resources in the phosphorite are used for flue gas desulfurization to obtain phosphogypsum, the phosphogypsum can be completely recycled, the flue gas desulfurization cost is reduced, and the desulfurization efficiency is improved; sulfur dioxide in the flue gas is used for wet-process phosphoric acid production instead of sulfuric acid, so that the sulfuric acid raw material cost required by phosphoric acid production is saved. The conversion of the desulfurized gypsum into the phosphogypsum is realized, the resource value utilization is realized, the environmental influence is reduced, and the utilization rate of phosphorus resources is improved. The method is very suitable for boiler flue gas desulfurization, phosphoric acid production and gypsum co-production.

Description

Technical Field

[0001] The utility model relates to a flue gas desulfurization method, in particular to a flue gas desulfurization and co-production phosphoric acid and gypsum production circulation system. Background Art

[0002] Boiler flue gas process is divided into dry and wet methods according to the form of desulfurizer. Dry and semi-dry methods have the characteristics of low investment and low energy consumption, and occupy a certain market share in the field of small and medium-sized coal-fired boilers, but their desulfurization efficiency is not higher than 90%, and their market space is limited; wet desulfurization can achieve a desulfurization efficiency of more than 95%, which is the main development direction. According to the properties of the desulfurizer, it can be divided into limestone-gypsum method, ammonia method, double alkali method, magnesium method, organic ammonia method, etc. At present, the most used is limestone-gypsum method, which accounts for more than 90% of the market share. Limestone desulfurization requires the mining of limestone mines. The desulfurization reaction involves a three-phase reaction of gas, liquid and solid, and the mass transfer efficiency is low, which reduces the desulfurization efficiency. The desulfurization gypsum product produced by desulfurization contains a large amount of calcium carbonate, which has poor performance and cannot be promoted and applied. It needs to occupy land for storage, causing secondary pollution.

[0003] The production of wet phosphoric acid requires the construction of a sulfuric acid plant and the purchase of sulfur or pyrite raw materials. The construction investment is large and the raw material cost is high. If sulfur dioxide in the flue gas is used instead of sulfuric acid, the cost of phosphoric acid can be greatly reduced, and the currently unusable desulfurization gypsum can be converted into phosphogypsum that can be utilized as a resource.

[0004] And design a connected processing circulation system to achieve and combine the advantages and disadvantages of each process, realize maximum resource utilization and reduce pollution. Based on this purpose, there is currently no phosphate rock flue gas desulfurization production of phosphoric acid and gypsum production circulation system. Utility Model Content

[0005] In order to solve the above problems, the utility model proposes a phosphoric acid and gypsum production circulation system, characterized in that the circulation system includes a desulfurization tower, a slurry delivery pump, a gypsum filter, and an acid hydrolysis reactor, which are connected in sequence through pipelines, and the acid hydrolysis reactor is also connected to the desulfurization tower through a pipeline to form a loop.

[0006] The desulfurization tower is used for the reaction of sulfur dioxide in flue gas with calcium-containing slurry to produce calcium sulfate (gypsum), thereby removing sulfur dioxide from flue gas.

[0007] The slurry delivery pump is used to deliver the gypsum slurry in the desulfurization tower to the gypsum filter.

[0008] The gypsum filter is used to filter the gypsum slurry to obtain gypsum filter cake and phosphoric acid filtrate, and the phosphoric acid filtrate flows into the acid decomposition reactor.

[0009] The acid decomposition reactor is used for the acid decomposition reaction of phosphoric acid and phosphate rock to obtain calcium-containing acid solution which flows into the desulfurization tower for desulfurization.

[0010] The acid decomposer in the system is provided with a crushing structure to assist the reaction and decompose the calcium-containing acid solution, so that the phosphate ore and phosphoric acid undergo a decomposition reaction to obtain the calcium-containing acid solution and reflux it to the desulfurization tower, so that the calcium ions react chemically with sulfur trioxide and sulfur dioxide in the flue gas to generate calcium sulfate and calcium sulfite precipitation, thereby achieving process continuity and connecting the entire system for operation.

[0011] The above system is also a phosphate rock flue gas desulfurization production phosphoric acid and gypsum production circulation system.

[0012] The following can be obtained by using the above system:

[0013] The calcium-containing acid solution produced by the reaction of phosphoric acid and phosphate rock is used as a desulfurizer, and the calcium resources in the phosphate rock are used for flue gas desulfurization to obtain phosphogypsum. The phosphogypsum can be fully utilized as a resource, reducing the cost of flue gas desulfurization and improving the desulfurization efficiency; the sulfur dioxide in the flue gas is used instead of sulfuric acid for wet phosphoric acid production, eliminating the cost of sulfuric acid raw materials required for phosphoric acid production. The utility model improves the economic efficiency of the industry, and the desulfurized gypsum is converted into phosphogypsum for resource value utilization, solving the major problems of land occupation and secondary pollution of desulfurized gypsum, reducing environmental impact, and improving the utilization rate of phosphorus resources. It is very suitable for boiler flue gas desulfurization and phosphoric acid production, using calcium resources in phosphate rock instead of traditional limestone flue gas desulfurization, reducing the cost of boiler flue gas desulfurization and improving the desulfurization efficiency; using sulfur dioxide flue gas instead of sulfuric acid for phosphoric acid production, eliminating the cost of sulfuric acid raw materials required for phosphoric acid production, effectively realizing the combination of the two industries, reducing the cost of raw materials, improving economic efficiency, and no need to mine limestone for desulfurization, reducing the impact on the environment.

[0014] The decomposer in the system is equipped with a crushing structure to assist the reaction and decompose the calcium-containing acid solution, so that the phosphate ore decomposes with phosphoric acid to obtain the calcium-containing acid solution and flows back to the desulfurization tower, so that the calcium ions react chemically with sulfur trioxide and sulfur dioxide in the flue gas to generate calcium sulfate and calcium sulfite precipitates, thus realizing the continuity of the process and the connected operation of the overall system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a circulation system diagram of the utility model.

[0016] Figure 2 It is a schematic diagram of the structure of the decomposer of the utility model.

[0017] Figure 3 It is a schematic diagram of the internal structure of the decomposer of the utility model.

[0018] Figure 4 For the utility model Figure 3 A is a schematic diagram of the enlarged structure.

[0019] Numbers in the figure: 1. desulfurization tower; 2. slurry delivery pump; 3. gypsum filter; 4. acid hydrolysis reactor; 511. decomposer shell; 512. feed pipe; 513. drive motor; 514. rotating rod; 515. crushing roller; 516. first pulley; 517. connecting belt; 518. second pulley; 519. first gear; 520. second gear; 521. rotating rod; 522. connecting piece; 523. connecting rod; 524. cleaning roller; 525. discharging piece; 526. vertical rod; 527. horizontal plate; 528. moving part. DETAILED DESCRIPTION

[0020] The utility model is further described below in conjunction with flow charts and embodiments.

[0021] A phosphoric acid and gypsum circulation production system, the system comprises a desulfurization tower 1, a slurry delivery pump 2, a gypsum filter 3, and an acidolysis reactor 4, which are sequentially connected through pipelines, and the acidolysis reactor 4 is also connected to the desulfurization tower 1 through a pipeline to form a loop;

[0022] The desulfurization tower 1 is used for the reaction of sulfur dioxide in flue gas with calcium-containing slurry to produce calcium sulfate (gypsum), thereby removing sulfur dioxide from flue gas; the slurry delivery pump 2 is used for delivering gypsum slurry; the gypsum filter 3 is used for filtering gypsum slurry to obtain gypsum filter cake and phosphoric acid filtrate; the acid decomposition reactor 4 is used for the acid decomposition reaction of phosphoric acid and phosphate rock to obtain calcium-containing acid solution.

[0023] A method for desulfurizing and co-producing phosphoric acid and gypsum based on the system using dilute phosphate phosphate rock flue gas, wherein an acid hydrolysis reactor 4 and a desulfurization tower 1 for sulfur dioxide flue gas are respectively connected to a gypsum filter 3 to form a desulfurization and simultaneous production of phosphoric acid and gypsum circulation system, and a cycle of desulfurization in the desulfurization tower, production of phosphoric acid and co-production of gypsum is achieved through the corresponding process of the reaction product. The reaction steps and cycles of the process include the following:

[0024] A. The raw materials phosphate rock and dilute phosphoric acid enter the acid decomposition reactor 4, where the phosphate rock and phosphoric acid undergo an acid decomposition reaction to obtain a calcium-containing acid solution, which enters the desulfurization tower (1);

[0025] B. The sulfur dioxide in the flue gas in the desulfurization tower reacts with the calcium-containing acid solution to generate calcium sulfite precipitation, and the calcium sulfite further undergoes an oxidation reaction to obtain calcium sulfate. The calcium sulfate slurry is transported to the gypsum filter 3 through the slurry pump 2;

[0026] C. The filter cake produced by the filter is a calcium sulfate (gypsum) product, and the filtrate is dilute phosphoric acid, a portion of which is extracted as a product, and a portion is recycled back to the acid decomposition reactor 4 as a dilute phosphoric acid raw material;

[0027] The above three steps form desulfurization, production of phosphoric acid and co-production of gypsum for cyclic processing, so as to achieve phosphate rock flue gas desulfurization and production of phosphate rock and co-production of gypsum.

[0028] The production circulation system comprises the above-mentioned desulfurization tower 1, slurry delivery pump 2, gypsum filter 3, and acid hydrolysis reactor 4, and the desulfurization tower 1, slurry delivery pump 2, gypsum filter 3, and acid hydrolysis reactor 4 are connected in sequence through pipelines.

[0029] The reaction mechanism is: the acidolysis mechanism uses dilute phosphoric acid to react with phosphate rock to generate a calcium-containing acidolysis solution, which contains water-soluble monocalcium phosphate, and the reaction formula is Ca5F(PO4)3+7H3PO4→5Ca(H2PO4)2+HF. The desulfurization mechanism uses the monocalcium phosphate in the calcium-containing acidolysis solution to react chemically with sulfur dioxide in the flue gas to generate calcium sulfite precipitate, which is further oxidized to obtain calcium sulfate (gypsum) precipitate, and the reaction formula is Ca(H2PO4)2+SO2+H20→CaSO3+2H3PO4, 2CaSO3+O2→2CaSO4.

[0030] The raw material of step A, dilute phosphoric acid, is: H3PO4 25-35%, the raw material phosphate rock P2O5 is 30-31%, and the acid decomposition reaction process conditions are: reaction time 2-3 hours, reaction temperature normal temperature, liquid-solid ratio 2.5-3.0:1.

[0031] In step B, the boiler flue gas temperature is 130° C. to 150° C., the calcium salt concentration (calculated as calcium) is 5% to 10%, and the liquid-to-gas ratio is 1:1000.

[0032] The above-mentioned method for desulfurizing phosphate rock flue gas based on dilute phosphoric acid and co-producing phosphoric acid and gypsum is also a method for desulfurizing phosphate rock flue gas based on dilute phosphoric acid.

[0033] refer to Figure 1 The raw materials phosphate rock and dilute phosphoric acid (only required for the first start-up) enter the acid-acid hydrolysis reactor 4, in which the phosphate rock and phosphoric acid undergo an acid decomposition reaction to obtain a calcium-containing acid hydrolysis solution, which enters the desulfurization tower 1, in which the sulfur dioxide in the flue gas reacts with the calcium-containing acid hydrolysis solution to generate a calcium sulfite precipitate, which further undergoes an oxidation reaction to obtain calcium sulfate (gypsum), and the calcium sulfate slurry is conveyed to the gypsum filter 3 through a slurry conveying pump 2; the filter cake produced by the filter is a calcium sulfate (gypsum) product, and the filtrate is dilute phosphoric acid, a part of which is extracted as a product, and a part is recycled back to the acid-acid hydrolysis reactor 4 as a dilute phosphoric acid raw material, and the processing is repeated in sequence to realize the combination of multiple processes, and phosphoric acid and gypsum are co-produced based on the flue gas desulfurization of the dilute phosphoric acid phosphate rock.

[0034] The acid decomposer can be referred to as follows: as shown in the figure, the acid decomposer 4 includes a decomposer shell 511, a feed pipe 512 is arranged on the upper end surface of the decomposer shell 511, and two groups of drive motors 513 are arranged on the outer wall of the decomposer shell 511. The output ends of the two groups of drive motors 513 pass through the decomposer shell 511 and extend to the inside of the decomposer shell 511, and are connected to a group of rotating rods 514. The other ends of the two groups of rotating rods 514 are connected to the inner wall of the other end of the decomposer shell 511, and the outer walls of the two groups of rotating rods 514 are sleeved with a group of crushing rollers 515; the outer walls of the two groups of rotating rods 514 are sleeved with a group of first belts 516, and the outer sides of the two groups of first pulleys 516 are sleeved with a group of connecting belts 517, and the inner walls of the other sides of the two groups of connecting belts 517 are sleeved with a group of first belts 516. A group of second pulleys 518 are provided on each of the two groups of first pulleys 516 and the second pulleys 518 are rotatably connected to the inner wall of the decomposer housing 511; a group of first gears 519 are provided on the side walls of the two groups of second pulleys 518, and a group of second gears 520 are meshed and connected to one side of the two groups of first gears 519, and a group of rotating rods 521 are provided inside the two groups of second gears 520, and the two ends of the two groups of rotating rods 521 are respectively provided on the inner walls of the two sides of the decomposer housing 511; two groups of connecting members 522 are sleeved on the outer walls of the two groups of rotating rods 521, and multiple groups of connecting rods 523 are connected to the outer walls of the two groups of connecting members 522, and a group of cleaning rollers 524 are provided on the other ends of the multiple groups of connecting rods 523, and the cleaning rollers 524 are in contact with the crushing rollers 515;

[0035] A discharge piece 525 is provided on the lower end wall of the decomposer housing 511; the material produced by the decomposition reaction can be discharged by providing the discharge piece 525. A set of vertical rods 526 are provided at the four corners of the lower end surface of the decomposer housing 511, and two sets of horizontal plates 527 are provided on the lower end surfaces of the multiple sets of vertical rods 526. A set of moving pieces 528 are provided at both ends of the lower end surfaces of the two sets of horizontal plates 527; the vertical rods 526 can support the horizontal plates 527, and the horizontal plates 527 can support the moving pieces 528, and the moving pieces 528 can facilitate the transfer of the device.

[0036] When the acid decomposer 5 is in use, the raw phosphate ore and phosphoric acid are transported to the interior of the decomposer housing 511 through the feed pipe 512, and two sets of drive motors 513 are started at the same time. The two sets of drive motors 513 drive two sets of crushing rollers 515 to crush the raw phosphate ore and phosphoric acid through two sets of rotating rods 514, so that the raw phosphate ore and the phosphoric acid provided for the first time can be decomposed better and faster. While rotating, the rotating rod 514 drives the first gear 519 to rotate through the first pulley 516, the connecting belt 517 and the second pulley 518. The first gear 519 drives the rotating rod 21 to rotate through the second gear 520. The rotating rod 521 drives multiple sets of cleaning rollers 524 to rotate through the connecting piece 522, so that the multiple sets of cleaning rollers 524 can scrape the residue on the crushing rollers 515 to avoid the raw materials remaining on the crushing rollers 515. It is relatively practical and ensures the full decomposition reaction of the material. The crushing structure is set to assist the reaction to decompose the calcium-containing acid solution, so that the phosphate ore and phosphoric acid undergo a decomposition reaction to obtain the calcium-containing acid solution and return it to the desulfurization tower, so that the calcium ions react chemically with sulfur trioxide and sulfur dioxide in the flue gas to generate calcium sulfate and calcium sulfite precipitation, thereby realizing the continuity of the process and the connected operation of the overall system.

[0037] The desulfurization tower, slurry delivery pump and gypsum filter in the system can be applied with existing technical equipment and will not be detailed here.

[0038] The above method or system is used to obtain the following:

[0039] The calcium-containing acid solution produced by the reaction of phosphoric acid and phosphate rock is used as a desulfurizer, and the calcium resources in the phosphate rock are used for flue gas desulfurization to obtain phosphogypsum. The phosphogypsum can be fully utilized as a resource, reducing the cost of flue gas desulfurization and improving the desulfurization efficiency; the sulfur dioxide in the flue gas is used instead of sulfuric acid for wet phosphoric acid production, eliminating the cost of sulfuric acid raw materials required for phosphoric acid production. The utility model improves the economic efficiency of the industry, and the desulfurized gypsum is converted into phosphogypsum for resource value utilization, solving the major problems of land occupation and secondary pollution of desulfurized gypsum, reducing environmental impact, and improving the utilization rate of phosphorus resources. It is very suitable for boiler flue gas desulfurization and phosphoric acid production, using calcium resources in phosphate rock instead of traditional limestone flue gas desulfurization, reducing the cost of boiler flue gas desulfurization and improving the desulfurization efficiency; using sulfur dioxide flue gas instead of sulfuric acid for phosphoric acid production, eliminating the cost of sulfuric acid raw materials required for phosphoric acid production, effectively realizing the combination of the two industries, reducing the cost of raw materials, improving economic efficiency, and no need to mine limestone for desulfurization, reducing the impact on the environment.

[0040] The above method and system are used for three-in-one processing, and the following data are obtained:

[0041] Embodiment 1

[0042] According to the requirements of the process flow shown in the figure, the phosphate rock is controlled at 100kg / h, and the composition of the phosphate rock is: P2O5 30%.

[0043] The phosphoric acid flow rate is controlled at 800 kg / h and the phosphoric acid concentration is about 36%.

[0044] Acid hydrolysis control reaction time: 120 minutes, temperature is room temperature.

[0045] Desulfurization tower control: boiler flue gas temperature 130℃~150℃, calcium salt concentration (calculated as calcium) 6%, liquid-gas ratio 1:1000.

[0046] Gypsum slurry storage tank control: agitator speed 60r / min residence time 8 hours.

[0047] According to the above process operation, the final analysis results are as follows:

[0048] Phosphoric acid: H3PO4 39.75%.

[0049] Gypsum: GaSO4 (containing two crystal waters) content 90.1%

[0050] Desulfurization tower: desulfurization efficiency is 95.6%, and the sulfur content of desulfurized tail gas is 56mg / M3.

[0051] Embodiment 2

[0052] According to the requirements of the process flow shown in the figure, the phosphate rock is controlled at 100kg / h, and the composition of the phosphate rock is: P2O5 30%, which needs to be removed.

[0053] The phosphoric acid flow rate was controlled at 900 kg / h and the phosphoric acid concentration was about 36%.

[0054] Acid hydrolysis control reaction time: 120 minutes, temperature is room temperature.

[0055] Desulfurization tower control: boiler flue gas temperature 130℃~150℃, calcium salt concentration (calculated as calcium) 5.2%, liquid-gas ratio 1:1000.

[0056] Gypsum slurry storage tank control: agitator speed 60r / min residence time 7 hours.

[0057] According to the above process operation, the final analysis results are as follows:

[0058] Phosphoric acid: H3PO4 37%.

[0059] Gypsum: GaSO4 (containing two crystal waters) content 90.5%

[0060] Desulfurization tower: desulfurization efficiency is 95.9%, and the sulfur content of desulfurized tail gas is 58mg / M3.

[0061] Embodiment 3

[0062] According to the requirements of the process flow shown in the figure, the phosphate rock is controlled at 200kg / h, and the composition of the phosphate rock is: P2O5 30%, which needs to be removed.

[0063] The phosphoric acid flow rate is controlled at 1600 kg / h and the phosphoric acid concentration is about 36%.

[0064] Acid hydrolysis control reaction time: 150 minutes, temperature is room temperature.

[0065] Desulfurization tower control: boiler flue gas temperature 130℃~150℃, calcium salt concentration (calculated as calcium) 6.5%, liquid-gas ratio 1:1000.

[0066] Gypsum slurry storage tank control: agitator speed 60r / min residence time 6 hours.

[0067] According to the above process operation, the final analysis results are as follows:

[0068] Phosphoric acid: H3PO4 40.1%.

[0069] Gypsum: GaSO4 (containing two crystal waters) content 90.7%

[0070] Desulfurization tower: desulfurization efficiency is 95.3%, and the sulfur content of desulfurized tail gas is 58mg / M3.

[0071] Through the above data, it can be fully obtained again: the calcium-containing acid solution produced by the reaction of phosphoric acid and phosphate rock is used as a desulfurizer, and the calcium resources in the phosphate rock are used for flue gas desulfurization to obtain phosphogypsum, and the phosphogypsum can be fully utilized as a resource, reducing the cost of flue gas desulfurization and improving the desulfurization efficiency; sulfur dioxide in the flue gas is used instead of sulfuric acid for wet phosphoric acid production, eliminating the cost of sulfuric acid raw materials required for phosphoric acid production. The utility model improves the economic efficiency of the industry, and the desulfurized gypsum is converted into phosphogypsum for resource value utilization, which solves the major problems of desulfurized gypsum occupying land and secondary pollution, reduces environmental impact, and improves the utilization rate of phosphorus resources. It is very suitable for boiler flue gas desulfurization and phosphoric acid production, and the calcium resources in the phosphate rock are used to replace the traditional limestone flue gas desulfurization, which reduces the cost of boiler flue gas desulfurization and improves the desulfurization efficiency; sulfur dioxide flue gas is used instead of sulfuric acid for phosphoric acid production, eliminating the cost of sulfuric acid raw materials required for phosphoric acid production, effectively realizing the combination of the two industries, and realizing the co-production of phosphoric acid and gypsum based on dilute phosphoric acid phosphate rock flue gas desulfurization.

Claims

1. A phosphoric acid and gypsum production circulation system, characterized in that: The circulation system comprises a desulfurization tower (1), a slurry delivery pump (2), a gypsum filter (3), and an acid hydrolysis reactor (4), which are connected in sequence through pipelines. The acid hydrolysis reactor (4) is also connected to the desulfurization tower (1) through a pipeline to form a loop.

2. The phosphoric acid and gypsum production circulation system according to claim 1, characterized in that: The desulfurization tower (1) is used for reacting sulfur dioxide in flue gas with calcium-containing slurry to produce calcium sulfate (gypsum), thereby removing sulfur dioxide from flue gas.

3. The phosphoric acid and gypsum production circulation system according to claim 1, characterized in that: The slurry delivery pump (2) is used to deliver the gypsum slurry in the desulfurization tower (1) to the gypsum filter (3).

4. The phosphoric acid and gypsum production circulation system according to claim 1, characterized in that: The gypsum filter (3) is used to filter the gypsum slurry to obtain gypsum filter cake and phosphoric acid filtrate, and the phosphoric acid filtrate flows into the acidolysis reactor (4).

5. The phosphoric acid and gypsum production circulation system according to claim 1, characterized in that: The acidolysis reactor (4) is used for the acidolysis reaction of phosphoric acid and phosphate rock to obtain a calcium-containing acidolysis liquid which flows into the desulfurization tower (1) for desulfurization.

6. The phosphoric acid and gypsum production circulation system according to claim 1, characterized in that: The acid decomposer in the system is equipped with a crushing structure to assist the reaction and decompose the calcium-containing acid solution, so that the phosphate ore and phosphoric acid undergo a decomposition reaction to obtain the calcium-containing acid solution which is refluxed to the desulfurization tower, thereby achieving a chemical reaction between the calcium ions and the sulfur trioxide and sulfur dioxide in the flue gas to generate calcium sulfate and calcium sulfite precipitation, thereby achieving process continuity and connected operation of the overall system.

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