A process and equipment for producing fertilizer using thiourea dioxide wastewater

Abstract

The invention discloses a device for producing fertilizer from thiourea dioxide wastewater, comprising an oxidation tower, a potassium hydroxide absorption tower, a sulfuric acid absorption tower, an induced draft fan, and a filter press, wherein the induced draft fan is arranged between the oxidation tower and the potassium hydroxide absorption tower. The invention has high heating temperature and low vacuum degree, and the use effect of the obtained fertilizer is good. In the process of reduced pressure evaporation, the lower the vacuum degree, the lower the boiling point of the solution can be, and the evaporation operation can be strengthened.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and in particular relates to equipment and a process for producing fertilizer from thiourea dioxide wastewater. Background Art

[0002] At present, the COD and ammonia nitrogen of thiourea dioxide wastewater are relatively high, which is difficult to treat. Conventional equipment has high requirements, which is not only power-consuming, but also contains more by-products and impurities in the recovered thiourea dioxide, poor stability, and high cost. After distillation for a period of time, there are too many by-products, and the viscosity of the material increases, making it impossible to continue distillation. At present, thiourea dioxide is also used as a fertilizer, but it is used to repair organic pollution, and new thiourea dioxide is added. There is no utilization of waste, and a good technical effect is achieved. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a device and process for producing fertilizer from thiourea dioxide wastewater.

[0004] The technical solution adopted by the present invention is:

[0005] A device for producing fertilizer from thiourea dioxide wastewater comprises an oxidation tower, a potassium hydroxide absorption tower, a sulfuric acid absorption tower, an induced draft fan, and a filter press, wherein the induced draft fan is arranged between the oxidation tower and the potassium hydroxide absorption tower.

[0006] Preferably, it also includes an air compressor, which is arranged in the oxidation tower.

[0007] Preferably, the oxidation tower, potassium hydroxide absorption tower and sulfuric acid absorption tower are connected in sequence.

[0008] A process for producing fertilizer from thiourea dioxide wastewater comprises the following steps:

[0009] (1) Add an appropriate amount of potassium citrate to the thiourea dioxide wastewater;

[0010] (2) Using the heat generated by ice machine exchange during the production of thiourea dioxide for heating and oxidation;

[0011] (3) The moist air is absorbed by the potassium hydroxide absorption tower;

[0012] (4) The humidified air formed in step (3) is passed into a sulfuric acid absorption tower for absorption;

[0013] (5) The mixed solution is passed into a filter press for filtering;

[0014] (6) The solid obtained in step (5) is prepared into fertilizer granules.

[0015] Preferably, in (1), potassium citrate is 3-5% of the thiourea dioxide wastewater, and the pH value is 5-7.

[0016] Preferably, in (2), when the temperature of the thiourea dioxide wastewater reaches 40-50°C, the air compressor in the oxidation tower is turned on to make the vacuum degree in the oxidation tower -0.07~-0.08MPa, and the wastewater solution is fully contacted with the air through the spray head from the upper part of the oxidation tower.

[0017] Preferably, in (3), 15%-25% potassium hydroxide solution is used for absorption.

[0018] Preferably, in (4), 10% sulfuric acid solution is used for absorption.

[0019] Preferably, in (5), the solution of step (4) is combined with the thiourea dioxide wastewater solution in the oxidation tower to form a mixed solution.

[0020] Preferably, in (6), the dried solid is mixed evenly with furfural residue, animal feces, urea ammonium solution and water in a ratio of 5-6:8-10:5-6:20-25:1-2 to obtain a mixed fertilizer, and the mixed fertilizer is crushed by a pulverizer and put into a granulator to prepare fertilizer granules.

[0021] The beneficial effects of the present invention are:

[0022] (1) The present invention uses potassium citrate, which has five functions: 1. Adjusting pH value and increasing alkalinity to facilitate the decomposition of thiourea dioxide under alkaline conditions; 2. Desulfurization: reducing the sulfur spillage of flue gas generated by the decomposition of thiourea dioxide; 3. The source of potassium in fertilizer; 4. Citric acid chelates metal ions; 5. Citric acid is the source of organic matter.

[0023] (2) The heat generated during the thiourea dioxide reaction is utilized during evaporation, and no additional steam is consumed.

[0024] (3) The fertilizer is rich in elements by making full use of the trace elements rich in thiourea minerals produced by calcium carbide and the ammonia nitrogen and sulfur elements in thiourea dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the device of the present invention. DETAILED DESCRIPTION

[0026] like Figure 1 , a device for producing fertilizer from thiourea dioxide wastewater, comprising an oxidation tower 1, a potassium hydroxide absorption tower 2, a sulfuric acid absorption tower 3, an induced draft fan 4, and a filter press 5. The oxidation tower 1, the potassium hydroxide absorption tower 2, and the sulfuric acid absorption tower 3 are connected in sequence, the induced draft fan 4 is arranged in a pipeline between the oxidation tower 1 and the potassium hydroxide absorption tower 2, and also includes an air compressor 6, which is arranged in the oxidation tower 1.

[0027] Process 1

[0028] A process for producing fertilizer from thiourea dioxide wastewater, wherein the wastewater is the wastewater produced after centrifugation of thiourea dioxide crystal solids during the production of thiourea dioxide, and the main components of the wastewater are: 2% thiourea dioxide, 0.1% hydrogen peroxide, 0.2% thiourea, 0.1% thiourea trioxide, and 1% ammonium carbonate. The process comprises the following steps:

[0029] (1) adding an appropriate amount of potassium citrate to the thiourea dioxide wastewater, which may be 3% of the thiourea dioxide wastewater, and adjusting the pH value of the wastewater solution so that the pH value of the wastewater solution is 5; preferably, the pH value of the wastewater solution is 6;

[0030] (2) The production of thiourea dioxide fertilizer is carried out simultaneously with the production of thiourea dioxide. The heat generated by the exchange of ice machines during the production of thiourea dioxide is used to heat the wastewater whose pH value has been adjusted. When the temperature reaches 40°C, the air compressor in the oxidation tower is turned on to make the vacuum degree in the oxidation tower -0.07MPa. The wastewater is pumped into the oxidation tower so that the wastewater solution is sprayed from the top of the oxidation tower through the spray head. The wastewater is fully in contact with the air, and the ammonium sulfite in the wastewater is oxidized by the oxygen in the air into stable sulfates such as ammonium sulfate and potassium sulfate. During the wastewater spraying process, the wastewater solution is continuously decompressed and evaporated and is carried out through the induced draft fan above the oxidation tower.

[0031] (3) The humidified air is passed through a potassium hydroxide absorption tower, and the sulfur dioxide gas in the air is absorbed by a 15% potassium hydroxide solution; the potassium sulfate generated is then mixed into the fertilizer;

[0032] (4) The humidified air is passed through the sulfuric acid absorption tower again, and ammonia in the air is removed using a 10% sulfuric acid solution, which is then discharged into the air. The generated ammonium sulfate is mixed into the fertilizer.

[0033] (5) obtaining a mixed solution containing 10% potassium sulfite, 10% ammonium sulfite, 60% ammonium sulfate, and the remainder potassium sulfate, combining the mixed solution with the thiourea dioxide wastewater solution in the oxidation tower, passing the mixed solution into a filter press, starting the filter press for filter pressing, and repeating the filter pressing several times until a solid containing ammonium sulfate, potassium sulfate, and urea is obtained; and drying the solid at 60° C.;

[0034] (6) The dried solid is mixed with furfural residue, animal feces, urea ammonium solution and water in a ratio of 5:8:5:20:1 to obtain a mixed fertilizer, and the mixed fertilizer is crushed by a crusher and put into a granulator to prepare fertilizer granules.

[0035] Craft 2

[0036] A process for producing fertilizer from thiourea dioxide wastewater, wherein the wastewater is the wastewater produced after centrifugation of thiourea dioxide crystal solids during the production of thiourea dioxide, and the main components of the wastewater are: 3% thiourea dioxide, 0.15% hydrogen peroxide, 0.4% thiourea, 0.2% thiourea trioxide, and 3% ammonium carbonate. The process comprises the following steps:

[0037] (1) adding an appropriate amount of potassium citrate to the thiourea dioxide wastewater, which may be 5% of the thiourea dioxide wastewater, to adjust the pH value of the wastewater solution so that the pH value of the wastewater solution is 7;

[0038] (2) The production of thiourea dioxide fertilizer is carried out simultaneously with the production of thiourea dioxide. The heat generated by the ice machine exchange during the production of thiourea dioxide is used to heat the wastewater whose pH value has been adjusted. When the temperature reaches 50°C, the air compressor in the oxidation tower is turned on to make the vacuum degree in the oxidation tower -0.08MPa. The wastewater is pumped into the oxidation tower so that the wastewater solution is sprayed from the top of the oxidation tower through the spray head. The wastewater is fully in contact with the air, and the ammonium sulfite in the wastewater is oxidized by the oxygen in the air into stable sulfates such as ammonium sulfate and potassium sulfate. During the wastewater spraying process, the wastewater solution is continuously decompressed and evaporated and is carried out through the induced draft fan above the oxidation tower.

[0039] (3) The humidified air is passed through a potassium hydroxide absorption tower, and the sulfur dioxide gas in the air is absorbed by a 25% potassium hydroxide solution; the potassium sulfate generated is then mixed into the fertilizer;

[0040] (4) The humidified air is passed through the sulfuric acid absorption tower again, and ammonia in the air is removed using a 25% sulfuric acid solution, which is then discharged into the air. The generated ammonium sulfate is mixed into the fertilizer.

[0041] (5) obtaining a mixed solution containing 20% ​​potassium sulfite, 70% ammonium sulfate and the remainder potassium sulfate, combining the mixed solution with the thiourea dioxide wastewater solution in the oxidation tower, passing the mixed solution into a filter press, starting the filter press for filter pressing, and repeating the filter pressing several times until a solid containing ammonium sulfate, potassium sulfate and urea is obtained; and drying the solid at 60° C.;

[0042] (6) The dried solid is mixed with furfural residue, animal feces, urea ammonium solution and water in a ratio of 6:10:6:25:2 to obtain a mixed fertilizer, the mixed fertilizer is crushed by a crusher, and put into a granulator to prepare fertilizer granules.

[0043] Implementation Case 1

[0044] 0.2t of potassium citrate was added to 5 tons of thiourea dioxide wastewater, and its pH value was measured until the pH value of the wastewater solution was 6. The wastewater solution with adjusted pH value was heated to 50°C, and the oxidation tower was opened to adjust the vacuum degree in the oxidation tower to -0.08MPa. The wastewater was passed into the oxidation tower by a pump, so that the wastewater solution was sprayed from the upper part of the oxidation tower through the spray head. The wastewater was fully in contact with the air, and the ammonium sulfite salt in the wastewater was oxidized by the oxygen in the air into stable sulfates such as ammonium sulfate and potassium sulfate. During the wastewater spraying process, the wastewater solution was continuously decompressed and evaporated and brought out through the induced draft fan above the oxidation tower. A small amount of sulfur dioxide gas and ammonia were contained in the steam. The steam was passed into 25% potassium hydroxide solution and 25% sulfuric acid solution absorption towers in turn to remove sulfur dioxide and ammonia in the steam to obtain a mixed solution containing potassium sulfite, ammonium sulfite, ammonium sulfate and potassium sulfate. The thiourea dioxide wastewater is subjected to oxidation, reduced pressure evaporation and other treatments to obtain a thiourea dioxide wastewater concentrate, the thiourea dioxide wastewater concentrate is combined with a mixed solution of potassium sulfite, ammonium sulfite, ammonium sulfate and potassium sulfate, and the mixture is passed into a filter press, the filter press is turned on for filtration, and the filtration step is repeated for multiple times until a solid containing 78.5% of ammonium sulfate, 6.7% of potassium sulfate, 12.2% of urea and other substances is obtained, the solid mixture is dried at 60° C., the dried solid is uniformly mixed with furfural residue, animal feces, urea ammonium solution and water in a ratio of 5:8:5:25:1 to obtain a mixed fertilizer, the mixed fertilizer is crushed by a crusher, and the crushed mixed powder is put into a granulator to prepare fertilizer granules.

[0045] Implementation Case 2

[0046] 0.2t of potassium citrate was added to 5 tons of urea dioxide thiourea wastewater, and its pH value was measured until the pH value of the wastewater solution was 6. The wastewater solution with adjusted pH value was heated to 45°C, and the oxidation tower was opened to adjust the vacuum degree in the oxidation tower to -0.075MPa. The wastewater was passed into the oxidation tower by a pump, so that the wastewater solution was sprayed from the upper part of the oxidation tower through the spray head, and the wastewater was fully contacted with the air. The ammonium sulfite salt in the wastewater was oxidized by the oxygen in the air into stable sulfates such as ammonium sulfate and potassium sulfate. During the wastewater spraying process, the wastewater solution was continuously decompressed and evaporated and brought out through the induced draft fan above the oxidation tower. A small amount of sulfur dioxide gas and ammonia were contained in the steam. The steam was passed into 25% potassium hydroxide solution and 25% sulfuric acid solution absorption towers in turn to remove sulfur dioxide and ammonia in the steam to obtain a mixed solution containing potassium sulfite, ammonium sulfite, ammonium sulfate and potassium sulfate. The mixed solution was combined with the urea dioxide thiourea wastewater solution in the oxidation tower, and the decompression evaporation process was repeated more than once. The thiourea dioxide wastewater is subjected to oxidation, reduced pressure evaporation and other treatments to obtain a thiourea dioxide wastewater concentrate, the thiourea dioxide wastewater concentrate is combined with a mixed solution of potassium sulfite, ammonium sulfite, ammonium sulfate and potassium sulfate, and the mixture is passed into a filter press, the filter press is turned on for filtration, and the filtration step is repeated for multiple times until a solid containing 74.9% of ammonium sulfate, 5.4% of potassium sulfate, 8.9% of urea and other substances is obtained, the solid mixture is dried at 60° C., the dried solid is uniformly mixed with furfural residue, animal feces, urea ammonium solution and water in a ratio of 5:8:5:25:1 to obtain a mixed fertilizer, the mixed fertilizer is crushed by a crusher, and the crushed mixed powder is put into a granulator to prepare fertilizer granules.

[0047] Implementation Case 3

[0048] 0.2t of potassium citrate was added to 5 tons of urea dioxide thiourea wastewater, and its pH value was measured until the pH value of the wastewater solution was 6. The wastewater solution with adjusted pH value was heated to 40°C, and the oxidation tower was opened to adjust the vacuum degree in the oxidation tower to -0.07MPa. The wastewater was passed into the oxidation tower by a pump, so that the wastewater solution was sprayed from the upper part of the oxidation tower through the spray head, and the wastewater was fully contacted with the air. The ammonium sulfite salt in the wastewater was oxidized by the oxygen in the air into stable sulfates such as ammonium sulfate and potassium sulfate. During the wastewater spraying process, the wastewater solution was continuously decompressed and evaporated and brought out through the induced draft fan above the oxidation tower. A small amount of sulfur dioxide gas and ammonia were contained in the steam. The steam was passed into 25% potassium hydroxide solution and 25% sulfuric acid solution absorption towers in turn to remove sulfur dioxide and ammonia in the steam to obtain a mixed solution containing potassium sulfite, ammonium sulfite, ammonium sulfate and potassium sulfate. The mixed solution was combined with the urea dioxide thiourea wastewater solution in the oxidation tower, and the decompression evaporation process was repeated more than once. The thiourea dioxide wastewater is subjected to oxidation, reduced pressure evaporation and other treatments to obtain a thiourea dioxide wastewater concentrate, the thiourea dioxide wastewater concentrate is combined with a mixed solution of potassium sulfite, ammonium sulfite, ammonium sulfate and potassium sulfate, and the mixture is passed into a filter press, the filter press is turned on for filtration, and the filtration step is repeated multiple times until a solid containing 70.3% ammonium sulfate, 4.5% potassium sulfate, 6.7% urea and other substances is obtained, the solid mixture is dried at 60° C., the dried solid is uniformly mixed with furfural residue, animal feces, urea ammonium solution and water in a ratio of 5:8:5:25:1 to obtain a mixed fertilizer, the mixed fertilizer is crushed by a crusher, and the crushed mixed powder is put into a granulator to prepare fertilizer granules.

[0049] Data Validation

[0050] In order to further illustrate the application value of the present invention, a peanut test field was selected for experiment. The inventor divided the test field into 5 small plots, in which peanuts were planted at the same time, and 2 of them were selected as control groups. Control group 1 did not use fertilizer, control group 2 used ordinary fertilizer on the market (Jinan Shengwang, industrial-grade ammonium sulfate fertilizer), and the remaining 3 plots used fertilizers prepared in implementation cases 1-3 of the present invention, respectively, and set up labels. After statistical analysis, the results are as follows:

[0051]

[0052] The above data show that the use of the fertilizer of the present invention can effectively increase the yield of crops, and the present invention can effectively achieve high yield of crops and effectively treat and utilize thiourea dioxide wastewater to create economic benefits.

[0053] The invention has high heating temperature and low vacuum degree, and the obtained fertilizer has good use effect. The high wastewater heating temperature makes the solubility of various solutes in the wastewater better. Meanwhile, the higher the temperature of the wastewater, the higher the molecular energy and the more intense the activity during the wastewater spraying process, which increases the effective collision between the ammonium sulfite in the wastewater and the air molecules, so that more ammonium sulfite in the wastewater can be oxidized by oxygen in the air into stable sulfates such as ammonium sulfate and potassium sulfate, and further increases the content of ammonium sulfate and potassium sulfate in the finally obtained fertilizer.

[0054] During the process of reduced pressure evaporation, the lower the vacuum degree, the lower the boiling point of the solution can be, and the evaporation operation can be strengthened. Ammonium sulfate is generally used for crops, which can make the branches and leaves of crops grow vigorously. It can improve the quality and yield of fruits and enhance the resistance of crops to natural disasters. Potassium sulfate can also be used as a chemical fertilizer, which can make crops achieve continuous high quality and high yield.

[0055] Compared with common fertilizers, the fertilizer of the present invention contains multiple ingredients such as potassium sulfate, ammonium sulfate, urea, animal manure, etc., which complement each other and enable crops to achieve high yields.

Claims

1. A process for producing fertilizer using thiourea dioxide wastewater, characterized in that: The process is implemented by the following equipment: Equipment for producing fertilizer using thiourea dioxide wastewater, comprising an oxidation tower, a potassium hydroxide absorption tower, a sulfuric acid absorption tower, an induced draft fan, and a filter press, wherein the induced draft fan is arranged between the oxidation tower and the potassium hydroxide absorption tower; It also includes an air compressor, which is arranged in the oxidation tower; The oxidation tower, potassium hydroxide absorption tower and sulfuric acid absorption tower are connected in sequence; The process comprises the following steps: (1) Add an appropriate amount of potassium citrate to the thiourea dioxide wastewater to adjust the pH; (2) The fertilizer production is carried out simultaneously with the thiourea dioxide production. The wastewater whose pH value has been adjusted is heated by utilizing the heat generated by the ice machine exchange during the thiourea dioxide production process. When the temperature of the thiourea dioxide wastewater reaches 40-50° C., the air compressor in the oxidation tower is turned on to make the vacuum degree in the oxidation tower -0.07~-0.08MPa. The wastewater is passed into the oxidation tower so that the wastewater solution is sprayed from the upper part of the oxidation tower through the spray head. The wastewater is fully in contact with the air, and the ammonium sulfite in the wastewater is oxidized by the oxygen in the air into stable ammonium sulfate and potassium sulfate. (3) The moist air is absorbed by the potassium hydroxide absorption tower; (4) The humidified air formed in step (3) is passed into a sulfuric acid absorption tower for absorption to obtain a solution containing potassium sulfite, ammonium sulfate and potassium sulfate; (5) combining the solution of step (4) with the thiourea dioxide wastewater solution in the oxidation tower to form a mixed solution, and passing the mixed solution into a filter press for filtering; (6) mixing the solid obtained in step (5) with furfural residue, animal feces, urea ammonium solution, and water in a ratio of 5-6:8-10:5-6:20-25:1-2 to obtain a mixed fertilizer, crushing the mixed fertilizer with a crusher, and placing it in a granulator to prepare fertilizer granules; In step (1), potassium citrate is 3-5% of the thiourea dioxide wastewater, and the pH value is adjusted to 5-7.

2. A process for producing fertilizer using thiourea dioxide wastewater as claimed in claim 1, characterized in that: Step (1), the main components of the wastewater are: 2% thiourea dioxide, 0.1% hydrogen peroxide, 0.2% thiourea, 0.1% thiourea trioxide, and 1% ammonium carbonate; Alternatively, the main components of the wastewater are: 3% thiourea dioxide, 0.15% hydrogen peroxide, 0.4% thiourea, 0.2% thiourea trioxide, and 3% ammonium carbonate.

3. A process for producing fertilizer using thiourea dioxide wastewater as claimed in claim 1, characterized in that: In step (3), 15%-25% potassium hydroxide solution is used for absorption.

4. A process for producing fertilizer using thiourea dioxide wastewater as claimed in claim 1, characterized in that: In step (4), absorption is performed using a 10% sulfuric acid solution.

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