CN102107887A - Ammonia gas recovery method, ammonium sulfate solution concentration measurement method and ammonium sulfate solution concentration control method - Google Patents

Abstract

The invention discloses an ammonia recovery method, a concentration measurement method of ammonium sulfate solution and a concentration control method of ammonium sulfate solution, the ammonia processing method of the invention provides sulfuric acid solution with weight percentage concentration of 1-98% as reactant, ammonia and the reactant are subjected to batch reaction or continuous reaction to generate ammonium sulfate solution with weight percentage concentration of 1-73%, thereby providing high-concentration ammonium sulfate solution, solving the defects that ammonia dissolved in water can not be recovered and the ammonia needs to be concentrated again for recovery, the concentration measurement method of ammonium sulfate solution of the invention judges whether the weight percentage concentration of ammonium sulfate solution accords with a default value by the pH value or the pH value and the conductivity of the ammonium sulfate solution, the concentration control method of ammonium sulfate solution of the invention controls the concentration of ammonium sulfate solution by controlling the amount of sulfuric acid in the reactant, the invention can be used for the subsequent treatment of the industrial waste gas containing ammonia gas and provides a new method for producing raw materials of chemical fertilizers.

Description

Ammonia recovery method, concentration measurement method of ammonium sulfate solution and concentration control method of ammonium sulfate solution

technical field

The present invention relates to an ammonia gas recovery method, a method for measuring the concentration of ammonium sulfate solution and a method for controlling the concentration of ammonium sulfate solution, in particular to a method for recovering ammonia gas by dissolving ammonia gas in high-concentration sulfuric acid to produce high-concentration ammonium sulfate , the method for measuring the concentration of ammonium sulfate solution and the method for obtaining the concentration of ammonium sulfate solution by measuring pH value or pH value and electrical conductivity.

Background technique

Ammonia is a basic raw material in many industries and industries, including petrochemical industry, refrigeration industry and fertilizer manufacturing industry. Ammonia is irritating and dangerous in industrial safety, health and environmental protection. Therefore, proper handling of ammonia is extremely important .

At present, ammonia-containing waste gas discharged from industry is often treated by dissolving in water, because ammonia has a very high solubility. However, ammonia-containing wastewater has great pollution to the environment and has not completely solved the problem. If it is necessary to recycle ammonia-containing wastewater, cumbersome follow-up treatment is still required, such as concentration with high back pressure and reverse osmosis membrane. Although the purpose of environmental protection is achieved, the required equipment and expenditure are not in line with the cost.

Taiwan Patent Application No. 274057: Harmless treatment method for waste gas containing ammonia, which discloses a treatment method for decomposing ammonia gas into nitrogen oxides with an oxidation catalyst. However, the decomposed nitrogen dioxide is the main source of photochemical smog. The reactant, the nitrogen dioxide emitted by the reaction again may cause secondary pollution of the air.

Contents of the invention

In view of this, the purpose of the present invention is exactly to provide a kind of ammonia recovery method, the concentration measurement method of ammonium sulfate solution and the concentration control method of ammonium sulfate solution, to provide a kind of ammonia gas that ammonia gas is synthesized into high-concentration ammonium sulfate The recovery method, the concentration measurement method of the ammonium sulfate solution and the concentration control method of the ammonium sulfate solution are used to solve the problems in the prior art that a large amount of ammonia-containing waste water is generated or the recycling process is cumbersome.

According to the purpose of the present invention, propose a kind of ammonia recovery method, it comprises the following steps:

Step 1: providing a first sulfuric acid solution with a concentration of 1% to 98% by weight as a reactant; and

Step 2: making ammonia gas react with the reactant to produce an ammonium sulfate solution with a weight percent concentration of 1% to 73%.

The reaction of the ammonia gas and the reactant described in the above step 2 is to first react the ammonia gas with the reactant to produce ammonium sulfate until the pH value of the ammonium sulfate reaches a set value, and then continue to introduce the ammonia gas and the reactant, And maintain the pH value of the ammonium sulfate to the set value, while the ammonium sulfate is continuously exported to form a continuous reaction.

Wherein, the method for recovering ammonia gas of the present invention preferably includes step 3: adding a second sulfuric acid solution to the reactant in batches. The weight percent concentration of the resulting ammonium sulfate solution is preferably 25%. The pH value of ammonium sulfate can be used as the basis for judging the end of the control reaction, preferably reaching the end of the reaction when the pH value is 7.

According to another object of the present invention, a kind of concentration measuring method of ammonium sulfate solution is proposed, and it judges whether the weight percent concentration of ammonium sulfate solution meets a default value by measuring the pH value of ammonium sulfate solution, and ammonium sulfate solution is The ammonia gas reacts with a sulfuric acid solution with a concentration of 1% to 98% by weight to form it.

According to another object of the present invention, a kind of concentration measurement method of ammonium sulfate solution is proposed, system measures or controls the pH value of ammonium sulfate solution earlier, makes it meet a set value, then by measuring the conductivity of ammonium sulfate solution with Judging the weight percent concentration of the ammonium sulfate solution, wherein the ammonium sulfate solution is formed by reacting ammonia gas with a sulfuric acid solution with a weight percent concentration ranging from 1% to 98%.

According to still another object of the present invention, a kind of concentration control method of ammonium sulfate solution is proposed, and its ammonium sulfate solution is generated by the reaction of ammonia gas and a sulfuric acid solution with a concentration of 1% to 98% by weight. The amount of sulfuric acid in the solution to control the concentration of the ammonium sulfate solution.

Succeeding from the above, because of the concentration measurement method and the concentration control method of ammonium sulfate solution according to ammonia recovery method of the present invention, ammonium sulfate solution, have following effect:

(1) In the ammonia recovery method of the present invention, the ammonium sulfate produced by its recovery process can be used as a raw material for chemical fertilizers, thereby avoiding the discharge of ammonia-containing pollutants.

(2) The ammonia gas recovery method of the present invention may include the step of adding the second sulfuric acid solution in stages, thereby maintaining the concentration of sulfuric acid so as not to cause the problem of sulfuric acid escape.

(3) The ammonia gas recovery method of the present invention may include the step of dispersing the reactant into fine droplets, thereby increasing the contact area between the reactant and the ammonia gas and accelerating the reaction.

(4) The concentration measuring method of the ammonium sulfate solution of the present invention can judge the weight percent concentration of the ammonium sulfate solution by measuring the pH value of the ammonium sulfate solution, and the measurement is simple, fast and accurate.

(5) the concentration measuring method of ammonium sulfate solution of the present invention, by measuring or controlling the pH value of ammonium sulfate solution earlier in a set value range (for example, pH value is between 3～11), then measure ammonium sulfate solution Conductivity, using the linear correspondence between conductivity and weight percent concentration, can accurately determine the weight percent concentration of ammonium sulfate solution, and its measurement is also simple, fast and accurate.

(6) The concentration control method of ammonium sulfate solution of the present invention can control the concentration of this ammonium sulfate solution by controlling the amount of sulfuric acid in the sulfuric acid solution, and its control method is simple and convenient, easy to implement.

Description of drawings

Fig. 1 is the flow chart of ammonia recovery method of the present invention;

Fig. 2 is the implementation method flowchart of ammonia recovery method of the present invention;

Fig. 3 is the ammonium sulfate concentration and electrical conductivity diagram of the concentration measuring method of ammonium sulfate solution of the present invention;

Fig. 4 is the solution pH value of the concentration measuring method of ammonium sulfate solution of the present invention and conductivity relation figure;

Fig. 5 is according to the first implementation device schematic diagram of ammonia recovery method of the present invention;

Fig. 6 is according to the second implementing device schematic diagram of ammonia recovery method of the present invention;

Fig. 7 is a structural diagram of an ammonia recovery device according to the ammonia recovery method of the present invention.

Explanation of reference signs:

(31), (41): reaction tank

(32), (42): gas inlet

(33), (43): Reactant

(34): agitator

(44), (77): circulation pump

(35), (45): gas outlet

(46): Circulation pipeline

(48), (78): packed bed

(71), (81): Exhaust gas treatment chamber

(72): Exhaust gas enters the pipeline

(73): Ammonium sulfate discharge line

(74): Exhaust gas discharge pipeline after treatment

(75): Reactant circulation line

(76): Sulfuric acid addition pipeline.

Detailed ways

Please refer to Fig. 1, which is a flow chart of the ammonia recovery method of the present invention. Among the figure, the ammonia recovery method comprises the following steps:

Step 1: providing a first sulfuric acid solution with a concentration of 1%-98% by weight as a reactant; choosing a high-concentration first sulfuric acid as a reactant can increase the reaction rate and increase the product concentration.

Step 2: React ammonia gas with the reactant to produce an ammonium sulfate solution with a concentration of 1% to 73% by weight; feed ammonia gas and react it with the first sulfuric acid, the reaction equation is as follows:

NH _{3 (g)} +H ₂ O _(aq) →NH ₄ OH _(aq)

2NH ₄ OH _(aq) +H ₂ SO _4(aq) →(NH ₄ ) ₂ SO _4(aq) +2H ₂ O _(aq)

Net reaction: 2NH _3(g) +H ₂ SO _4(aq) →(NH ₄ ) ₂ SO _4(aq)

It is shown in the formula that after the complete reaction, the initial molar concentration of the first sulfuric acid of the reactant is the same as the final molar concentration of the product ammonium sulfate, thereby providing high-concentration ammonium sulfate as a raw material for chemical fertilizers, and simultaneously solving the problem of ammonia recovery in the prior art Defects.

Wherein, the weight percent concentration of ammonium sulfate solution is preferably 25%, and the pH value of the ammonium sulfate of the ammonia gas recovery method of the present invention can be used as the judging basis that the control reaction ends, and the ammonium sulfate pH value at the end of the reaction is preferably 1～20%. 13, more preferably 3-11, most preferably 7.

Please refer to Fig. 2, which is a flow chart of the implementation method of the ammonia gas recovery method of the present invention. Among the figure, the ammonia recovery method comprises the following steps:

Step 1: providing a first sulfuric acid solution with a concentration of 1%-98% by weight as a reactant; choosing a high-concentration first sulfuric acid as a reactant can increase the reaction rate and increase the product concentration.

Step 2: Dispersing the reactant into fine droplets; dispersing the reactant into fine droplets can increase the contact area between the reactant and ammonia gas and increase the reaction rate. In practice, it can be realized with a circulating pipeline and a spraying device.

Step 3: react ammonia gas with the reactant to produce an ammonium sulfate solution with a concentration of 1% to 73% by weight; feed ammonia gas and react it with the first sulfuric acid, the reaction equation is as follows:

NH _{3 (g)} +H ₂ O _(aq) →NH ₄ OH _(aq)

2NH ₄ OH _(aq) +H ₂ SO _4(aq) →(NH ₄ ) ₂ SO _4(aq) +2H ₂ O _(aq)

Net reaction: 2NH _3(g) +H ₂ SO _4(aq) →(NH ₄ ) ₂ SO _4(aq)

It is shown in the formula that after the complete reaction, the initial molar concentration of the first sulfuric acid of the reactant is the same as the final molar concentration of the product ammonium sulfate, thereby providing high-concentration ammonium sulfate as a raw material for chemical fertilizers, and simultaneously solving the problem of ammonia recovery in the prior art Defects.

Step 4: Add the second sulfuric acid solution in batches in the reactant, and the weight percent concentration of the second sulfuric acid solution is higher than that of the first sulfuric acid solution; concentrated sulfuric acid has a high vapor pressure and is volatile, so in this embodiment, a higher sulfuric acid solution is selected. Low-concentration sulfuric acid is used as the first sulfuric acid. As the reaction progresses, the second sulfuric acid with higher concentration is gradually added in stages, so as to maintain the concentration of sulfuric acid from being too high and cause the problem of sulfuric acid escape. For example, use weight percent The second sulfuric acid solution having a lower concentration than the first sulfuric acid solution can also accelerate the reaction.

Wherein, the weight percent concentration of ammonium sulfate solution is preferably 25%, and the pH value of the ammonium sulfate of the ammonia gas recovery method of the present invention can be used as the judging basis that the control reaction ends, and the ammonium sulfate pH value at the end of the reaction is preferably 1～ 13, more preferably 3-11, most preferably 7.

The concentration measuring method of ammonium sulfate solution of the present invention is to judge whether the weight percent concentration of ammonium sulfate solution meets a default value by measuring the pH value of ammonium sulfate solution, and ammonium sulfate solution is based on ammonia gas and weight percent concentration. It is formed by the reaction of 1% to 98% sulfuric acid solution. When ammonia gas reacts with sulfuric acid solution, the sulfuric acid content in the solution decreases and the overall pH value increases. After establishing a calibration curve using the pH value and weight percent concentration of the ammonium sulfate solution, That is, the pH value of the ammonium sulfate solution can be used to determine whether the weight percent concentration of the ammonium sulfate solution meets a default value, and the default value is to make the ammonium sulfate solution produced by the reaction directly supply as a raw material for chemical fertilizers without additional concentration treatment steps, The default value is preferably above 1%, and the weight percent concentration of the ammonium sulfate solution is preferably between 1% and 73%, more preferably 25%.

Among them, when the pH value of the ammonium sulfate solution is preferably between 1 and 13, the reaction of ammonia gas and sulfuric acid solution is close to the end of the reaction, more preferably when the pH value of the ammonium sulfate solution is between 3 and 11, the reaction between ammonia gas and sulfuric acid solution The reaction is close to the end of the reaction, when the pH value of the ammonium sulfate solution is optimally 7, the reaction of ammonia and sulfuric acid solution reaches the end of the reaction.

The concentration measuring method of ammonium sulfate solution of the present invention is to judge the weight percent concentration of ammonium sulfate solution by measuring the conductivity of ammonium sulfate solution, and ammonium sulfate solution is between 1%～98% with ammonia gas and weight percent concentration. % of sulfuric acid solution reacts to generate, when ammonia reacts with sulfuric acid solution, ammonium sulfate is gradually generated as the sulfuric acid content in the solution decreases, and the overall pH value rises, when the reaction proceeds until the pH value of the system solution is higher than 3, the system solution The electrical conductivity of ammonium sulfate mainly comes from the free ions dissociated from ammonium sulfate. At this time, as long as the conductivity of ammonium sulfate is measured, the weight percent concentration of ammonium sulfate can be known. That is to say, the present invention measures the concentration of ammonium sulfate with electrical conductivity, such as matching with measuring or controlling the pH value of ammonium sulfate, which can increase the accuracy. The above-mentioned measurement or control of the pH value of ammonium sulfate means that the pH value of the ammonium sulfate is between 1-13, or the pH value is between 3-11, preferably the pH value is 7.

The concentration measuring method of the above-mentioned ammonium sulfate solution utilizes the linear relationship between the conductivity of the ammonium sulfate solution and the weight percent concentration, and under the premise that the pH value of the ammonium sulfate meets a default value, the conductivity of the ammonium sulfate solution is used to judge the ammonium sulfate The weight percent concentration of solution, the relationship diagram of ammonium sulfate concentration and conductivity is as shown in Figure 3, the sulfuric acid solution pH value and conductivity relationship diagram is as shown in Figure 4, and the weight percent concentration of this ammonium sulfate solution, Its default value is preferably above 1%, and the weight percent concentration of the ammonium sulfate solution is preferably between 1% and 73%, more preferably 25%.

The concentration control method of the ammonium sulfate solution of the present invention, its ammonium sulfate solution is generated by the reaction of ammonia gas and a sulfuric acid solution with a concentration of 1% to 98% by weight, by controlling the amount of sulfuric acid in the sulfuric acid solution, to control the concentration of ammonium sulfate solution.

Among them, preferably the weight percent concentration of the ammonium sulfate solution is between 1% and 73%, more preferably the weight percent concentration of the ammonium sulfate solution is 25%. Preferably when the pH value of the ammonium sulfate solution is between 1 and 13, the reaction of ammonia gas and sulfuric acid solution is close to the end of the reaction, more preferably when the pH value of the ammonium sulfate solution is between 3 and 11, the reaction of ammonia gas and sulfuric acid solution Near the end of the reaction, preferably when the pH of the ammonium sulfate solution is 7, the reaction of ammonia gas and sulfuric acid solution reaches the end of the reaction.

Please refer to Fig. 5, which is a schematic diagram of the first implementing device according to the ammonia gas recovery method of the present invention, which is an embodiment of using "batch reaction" to carry out ammonia gas recovery, that is, the continuously discharged ammonia gas and the reaction The reagent 33 is emptied of the reaction tank 31 after the reaction has come to an end, and then a new reagent 33 is refilled to carry out the next batch of reactions with the subsequent ammonia gas discharged. In the figure, the first implementation device includes a reaction tank 31 , a gas inlet 32 , a reactant 33 , a stirrer 34 and a gas outlet 35 . The ammonia-containing industrial waste gas is introduced into the reaction tank 31 through the gas inlet 32. The gas inlet 32 is located under one side of the reaction tank 31, and the height is below the liquid level of the reactant 33. When the ammonia-containing industrial waste gas enters the reaction tank 31, it contacts When the reactant 33 starts to react, there is a stirrer 34 at the bottom of the reaction tank 31, which is immersed in the reactant 33 to stir the reactant 33 to accelerate the reaction of the ammonia-containing industrial waste gas and the reactant 33, and to make the reaction complete. The remaining industrial waste gas that cannot be dissolved in the reactant 33 is discharged from the reaction tank 31 through the gas outlet 35 .

Please refer to FIG. 6 , which is a schematic diagram of the second implementation device of the ammonia gas recovery method according to the present invention, and is also an embodiment of utilizing "batch reaction" for ammonia gas recovery. In the figure, the second implementation device includes a reaction tank 41 , a gas inlet 42 , a reactant 43 , a circulation pump 44 , a gas outlet 45 , a circulation pipeline 46 , a spraying device 47 and a packed bed 48 . Ammonia-containing industrial waste gas is introduced into the reaction tank 41 through the gas inlet 42. The gas inlet 42 is located below one side of the reaction tank 41, and the height is above the liquid level of the reactant 43. The circulation pipeline 46 is located on the other side of the reaction tank 41. The side is below, and the height is below the liquid level of the reactant 43. After the reactant 43 is pressurized by the circulation pipeline 46 and the circulation pump 44, it is dispersed into fine droplets by the spraying device 47 at the top of the reaction tank 41 and sprinkled downwards. By using the packed bed 48 to increase the contact area with the ammonia-containing industrial waste gas, when the ammonia-containing industrial waste gas enters the reaction tank 41, it will start to react when it contacts the reactant 43 sprinkled by the spraying device 47. It is arranged in the reaction tank 41 and located in the reaction tank The packed bed 48 above the liquid level of the reagent 43 increases the contact area between the reactant 43 and the ammonia-containing industrial waste gas to increase the reaction rate, and the rest of the industrial waste gas that cannot be dissolved in the reactant 43 is discharged from the reaction tank 41 through the gas outlet 45 .

Please refer to Fig. 7, which is a structural diagram of an ammonia gas recovery device according to the ammonia gas recovery method of the present invention, which is a method for utilizing "continuous reaction" to carry out ammonia gas recovery, that is, at the beginning of the reaction, the Sulfuric acid is filled in the waste gas treatment chamber 71, and then the ammonia-containing industrial waste gas is continuously introduced to carry out the first-stage reaction until the pH value of ammonium sulfate reaches a set value, for example, the pH value is 3. After that, the ammonia-containing industrial waste gas is continuously introduced The exhaust gas treatment chamber 71, and the reactant (ie sulfuric acid) is continuously introduced into the exhaust gas treatment chamber 71 to maintain the pH value of the ammonium sulfate at 3. At this time, the ammonium sulfate can be continuously discharged to form a "continuous reaction". In the figure, the ammonia gas recovery device includes a waste gas treatment chamber 71, a waste gas inlet pipeline 72, an ammonium sulfate discharge pipeline 73, a treated waste gas discharge pipeline 74, a reactant circulation pipeline 75, a sulfuric acid addition pipeline 76, a circulation pump 77 and a packed bed 78 . Ammonia-containing industrial waste gas is introduced into the waste gas treatment chamber 71 through the waste gas inlet pipeline 72, the waste gas inlet pipeline 72 is located under one side of the waste gas treatment chamber 71, and the reactant circulation pipeline 75 is located under the other side of the waste gas treatment chamber 71, so that The reactant is sprayed down from the top of the waste gas treatment chamber 71 through the reactant circulation pipeline 75, and the contact area with the ammonia-containing industrial waste gas is increased by the packed bed 78. When the ammonia-containing industrial waste gas enters the waste gas treatment chamber 71, it is exposed The reactant immediately starts to react, and the packed bed 78 arranged in the waste gas treatment cavity 71 further increases the contact area between the reactant and the ammonia-containing industrial waste gas to increase the reaction rate. After a period of time, sulfuric acid can be added through the sulfuric acid addition pipeline 76, The reaction is accelerated, and when the ammonium sulfate concentration reaches the default value, the ammonium sulfate can be discharged from the ammonium sulfate discharge pipeline 73, and the remaining industrial waste gas is discharged from the treated waste gas discharge pipeline 74.

The above descriptions are illustrative only, not restrictive. Any equivalent modification or change made without departing from the spirit and scope of the present invention shall be included in the scope of the appended patent application.

Claims (18)

1. A method for ammonia recovery, comprising the following steps: Step 1: providing a first sulfuric acid solution with a concentration of 1% to 98% by weight as a reactant; Step 2: making ammonia gas react with the reactant to produce an ammonium sulfate solution with a concentration of 1%-73% by weight. 2. The method for recovering ammonia gas as claimed in claim 1, further comprising step 3: adding a second sulfuric acid solution in portions to the reactant. 3. Ammonia gas recovery method as claimed in claim 1, it is with the pH value of ammonium sulfate as the judging basis that the control reaction ends. 4. The method for recovering ammonia gas as claimed in claim 3, wherein the pH value of ammonium sulfate is 1-13. 5. The method for recovering ammonia gas as claimed in claim 4, wherein the pH value of ammonium sulfate is 3-11. 6. A method for recovering ammonia as claimed in claim 1, wherein said step 2 makes ammonia react with the reactant, first makes ammonia react with the reactant to produce ammonium sulfate, until the pH value of ammonium sulfate reaches 1 Set the value, and then continue to introduce ammonia and reactants, and maintain the pH of ammonium sulfate at the set value, while ammonium sulfate continues to export. 7. a concentration measurement method of ammonium sulfate solution, it is to produce an ammonium sulfate solution according to the method described in claim 1, judge whether the weight percent concentration of this ammonium sulfate solution meets a default by the pH value of this ammonium sulfate solution value. 8. The method for measuring the concentration of ammonium sulfate solution as claimed in claim 7, wherein the weight percent concentration of the ammonium sulfate solution is 1%˜73%. 9. The method for measuring the concentration of ammonium sulfate solution according to claim 7, wherein when the pH value of the ammonium sulfate solution is between 1% and 13, the reaction between the ammonia gas and the reactant is close to the end of the reaction. 10. The method for measuring the concentration of ammonium sulfate solution as claimed in claim 9, wherein when the pH value of the ammonium sulfate solution is between 3 and 11, the reaction between the ammonia gas and the reactant is close to the end of the reaction. 11. a concentration measurement method of ammonium sulfate solution, it is to produce an ammonium sulfate solution according to the method described in claim 1, make the pH value of this ammonium sulfate solution first meet a default value, then by measuring the ammonium sulfate solution Conductivity judges the weight percent concentration of the ammonium sulfate solution. 12. The method for measuring the concentration of ammonium sulfate solution as claimed in claim 11, wherein the weight percent concentration of the ammonium sulfate solution is 1%-73%. 13. The method for measuring the concentration of ammonium sulfate solution as claimed in claim 11, wherein the pH value of the ammonium sulfate solution is between 1-13. 14. The method for measuring the concentration of ammonium sulfate solution as claimed in claim 11, wherein the pH value of the ammonium sulfate solution is between 3-11. 15. a concentration control method of ammonium sulfate solution, it is to produce an ammonium sulfate solution according to the method for claim 1, by controlling the sulfuric acid amount in the reactant, to control the concentration of this ammonium sulfate solution. 16. The method for controlling the concentration of ammonium sulfate solution as claimed in claim 15, wherein the weight percent concentration of the ammonium sulfate solution is 1%˜73%. 17. The method for controlling the concentration of ammonium sulfate solution as claimed in claim 15, wherein when the pH value of the ammonium sulfate solution is between 1-13, the reaction between the ammonia gas and the reactant is close to the end of the reaction. 18. The method for controlling the concentration of ammonium sulfate solution as claimed in claim 17, wherein when the pH value of the ammonium sulfate solution is between 3-11, the reaction between the ammonia gas and the reactant is close to the end of the reaction.

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