Production method of ammonium nitrate solution

Abstract

The invention relates to the technical field of ammonium nitrate production, and particularly provides an ammonium nitrate solution production method, which comprises: 1, sequentially passing a dilute nitric acid solution through a dechlorination tower, a bleaching tower and a nitric acid filter to obtain a finished product dilute nitric acid solution; 2, carrying out a neutralization reaction on ammonia gas and a dilute nitric acid solution; 3, the ammonium nitrate solution enters an evaporator to be concentrated, and alkaline steam is divided into two parts; step 4, condensing and recovering the part I, providing a heat source for the evaporator by the part II, and then mixing the part II with steam for separation; 5, after the steam and the ammonia gas are separated, the ammonia gas is recycled, and the steam enters an adsorption device after being condensed; step 6, the condensate is divided into desalted water and concentrated water by the adsorption device, and the concentrated water is introduced into the neutralization reactor as cooling water; 7, ammonium nitrate enters an intermediate tank after being concentrated, and a high-quality ammonium nitrate solution is obtained; the ammonium nitrate solution produced by the method is high in quality, stable in property and high in safety coefficient in the production, transportation and use processes.

Description

Technical Field

[0001] The invention relates to the technical field of ammonium nitrate production, and in particular to a method for producing an ammonium nitrate solution. Background Art

[0002] Ammonium nitrate is an ammonium salt with the chemical formula NH4NO3. It is a white crystalline powder, very soluble in water, easy to absorb moisture and form agglomerates. It absorbs a lot of heat when dissolved. It is an oxidant. It decomposes explosively when hit or heated, and decomposes when exposed to alkali. It is mainly used as a fertilizer and industrial and military explosives. Because ammonium nitrate is explosive, there are certain safety hazards in the production, transportation and use of ammonium nitrate, so more and more companies tend to choose ammonium nitrate solution products that are easy to use, have a higher safety factor and lower overall cost.

[0003] As more and more companies begin to pay attention to the safety issues of ammonium nitrate solution during production, storage and use, each company has put forward higher requirements for the quality of ammonium nitrate solution, and has stricter requirements on the concentration and pH index range of ammonium nitrate solution. Ammonium nitrate solution manufacturers usually use the neutralization method to produce ammonium nitrate solution, that is, to produce ammonium nitrate solution by the neutralization reaction of ammonia and dilute nitric acid. However, the neutralization method for producing ammonium nitrate solution has the following problems: (1) The neutralization reaction is an exothermic reaction, and the heat generated cannot be recycled, resulting in energy waste. (2) A large amount of circulating cooling water is required to control the reaction temperature and condense steam, resulting in energy waste. (3) It is impossible to accurately control the concentration and pH of the finished ammonium nitrate solution, resulting in low quality of ammonium nitrate solution and failure to meet customer needs. (4) It is impossible to accurately control the quality of raw materials such as dilute nitric acid and ammonia, resulting in certain safety hazards in the production, transportation and use of ammonium nitrate solution.

[0004] Therefore, providing a method for producing an ammonium nitrate solution with high safety factor and high quality has become an urgent problem to be solved. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for producing an ammonium nitrate solution, comprising the following steps:

[0006] Step 1, passing the dilute nitric acid solution through a dechlorination tower, a bleaching tower and a nitric acid filter in sequence, so that the chloride ion content in the dilute nitric acid solution is less than 10.0 mg / kg, the nitrogen oxide content is less than 20.0 mg / kg, and the iron ion content is less than 1.0 mg / kg, to obtain a finished dilute nitric acid solution;

[0007] Step 2, introducing ammonia gas and finished dilute nitric acid solution into a neutralization reactor, and introducing cooling water into the bottom of the neutralization reactor;

[0008] Step 3, in a neutralization reactor, the finished dilute nitric acid solution and ammonia gas form an ammonium nitrate solution, and the ammonia gas and water vapor are mixed to form alkaline steam;

[0009] Step 4: the alkaline steam is divided into two parts, part one is directly condensed and enters the ammonia recovery tower for recovery, and part two provides heat source for the evaporator, and then mixes with the steam flowing out of the evaporator and enters the separator together;

[0010] Step 5: The separator separates the steam and ammonia, the ammonia enters the ammonia recovery tower for recovery, and the steam condenses to form a condensate that enters the adsorption device;

[0011] Step 6: The adsorption device separates the condensate into desalted water and concentrated water, and the concentrated water is passed into the neutralization reactor as cooling water; nitric acid is passed into the ammonia recovery tower, and is neutralized with ammonia to form cooling water, which is passed into the bottom of the neutralizer;

[0012] Step seven, the ammonium nitrate solution enters the evaporator for concentration, and the mass fraction of the concentrated ammonium nitrate solution is 91-93%. After the concentration is completed, it enters the intermediate tank to obtain a high-quality ammonium nitrate solution.

[0013] Preferably, the mass fraction of the dilute nitric acid solution in step 1 is 58-65%.

[0014] Preferably, the dechlorination tower in step 1 is a plate-type dechlorination tower, the dechlorination time is > 2h / layer; the secondary air volume of the bleaching tower is 9000-12000Nm 3 / h, the nanofiltration membrane accuracy of the nitric acid filter is ≤2nm.

[0015] Preferably, step 2 further comprises heating the liquid ammonia to evaporate into ammonia gas, filtering it, continuing to heat it, and then introducing it into the neutralization reactor.

[0016] Preferably, the liquid ammonia is heated to 10-15°C and the ammonia gas is heated to 60-90°C.

[0017] Preferably, the acid-ammonia ratio of ammonia gas and dilute nitric acid introduced in step 2 is 7.0-7.5, and the acid-ammonia ratio = (m 酸 +m 氨 ) / m 氨 Most preferably, the pH of the solution can be adjusted by adjusting the acid-ammonia ratio, preferably pH 4.5-6.0.

[0018] Preferably, the temperature of the cooling water in step 2 is 80-95°C.

[0019] Preferably, the pressure of the neutralization reactor in step 3 is 0.26-0.36Mpa, and the temperature is 160-177°C.

[0020] Preferably, the volume ratio of part one to part two in step four is 1:(1-3).

[0021] Preferably, the evaporator in step 4 is a vacuum evaporator with a pressure of (-0.075)-(-0.04) MPa and a temperature of 120-150° C. Most preferably, the mass fraction of the ammonium nitrate solution is adjusted by adjusting the pressure of the evaporator.

[0022] The present invention has the following advantages:

[0023] (1) Before the dilute nitric acid solution enters the neutralization reactor, the present invention sequentially passes through a chlorine removal tower, a bleaching tower and a nitric acid filter to control the contents of chloride ions, nitrogen oxides and iron ions in the dilute nitric acid solution, further improve the purity of the nitric acid solution, stabilize the neutralization reaction temperature and pressure, and improve the safety factor in the production process and the quality of the finished ammonium nitrate.

[0024] (2) The present invention controls the acid-ammonia ratio in the neutralization reactor to keep the concentration of ammonium nitrate stable, thereby improving the quality of the finished ammonium nitrate solution, while stabilizing the neutralization reaction temperature and pressure to ensure production safety.

[0025] (3) The present invention adjusts the mass fraction and pH of the ammonium nitrate solution in real time by controlling the acid-ammonia ratio and the pressure of the evaporator, so that the mass fraction and pH of the ammonium nitrate solution are stably maintained within a safe range, thereby ensuring safety while improving the quality of the ammonium nitrate solution.

[0026] (4) The present invention utilizes superheated alkaline steam to provide a heat source for the evaporator, recovers the heat released by the neutralization reaction, improves resource utilization, and avoids waste of resources; the present invention reuses concentrated water and water recovered from ammonia neutralization as cooling water to the neutralization reactor, further improving resource utilization and avoiding waste of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 The present invention is a flow chart of the production method of ammonium nitrate solution. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] Test Example 1

[0031] 60L of dilute nitric acid solution with different contents of chloride ions, nitrogen oxides and iron ions were neutralized with 10L of ammonia in a neutralization reactor. The acid-ammonia ratio [(m 酸 +m 氨 ) / m 氨 ]=7. The ammonia temperature is 75°C, the starting temperature of the neutralization reactor is 160°C, the starting pressure is 0.26Mpa, and the cooling water feed flow rate is 3.7L / min. The pressure change and temperature change during the neutralization reaction, as well as the mass fraction of the ammonium nitrate solution, are detected respectively. The results are shown in Table 1.

[0032] Table 1

[0033]

[0034]

[0035] As shown in Table 1, under the same conditions of acid-ammonia ratio, ammonia temperature, starting temperature, starting pressure and cooling water feed flow rate, when the chloride ion in the dilute nitric acid solution is less than 10.0 mg / kg, the temperature and pressure variation range of the neutralization reaction is small, the neutralization reaction is relatively stable, and the quality of the ammonium nitrate solution is high; when the nitrogen oxide in the dilute nitric acid solution is less than 20.0 mg / kg, the temperature and pressure variation range of the neutralization reaction is small, the neutralization reaction is relatively stable, and the quality of the ammonium nitrate solution is high; when the iron ion content in the dilute nitric acid solution is less than 1.0 mg / kg, the temperature and pressure variation range of the neutralization reaction is small, the neutralization reaction is relatively stable, and the quality of the ammonium nitrate solution is high. Therefore, in order to improve the quality of the ammonium nitrate solution and ensure the stability of the neutralization reaction, the chloride ion content in the dilute nitric acid solution should be less than 10.0 mg / kg, the nitrogen oxide content should be less than 20.0 mg / kg, and the iron ion content should be less than 1.0 mg / kg.

[0036] Example 1

[0037] Step 1: Pass a 62% dilute nitric acid solution through a dechlorination tower, a bleaching tower and a nitric acid filter in sequence, so that the chloride ion content in the dilute nitric acid solution is less than 10.0 mg / kg, the nitrogen oxide content is less than 20.0 mg / kg, and the iron ion content is less than 1.0 mg / kg, and a finished dilute nitric acid solution is obtained; the dechlorination tower is a plate-type dechlorination tower, and the dechlorination time is 2.3 h / layer; the secondary air volume of the bleaching tower is 10000 Nm 3 / h, the nanofiltration membrane accuracy of the nitric acid filter is 1.8nm.

[0038] Step 2: Liquid ammonia is heated to 12°C and evaporated into ammonia gas. The ammonia gas is filtered and then heated to 75°C before being introduced into a neutralization reactor. The finished dilute nitric acid solution is diluted to an acid-ammonia ratio of 7.2 [(m 酸 +m氨 ) / m 氨 ] is introduced into the neutralization reactor, and cooling water is introduced into the bottom of the neutralization reactor, and the temperature of the cooling water is 90°C.

[0039] Step 3: In the neutralization reactor, the finished dilute nitric acid solution and ammonia form an ammonium nitrate solution and release heat. The ammonia mixes with water vapor to form alkaline steam. The pressure of the neutralization reactor is controlled at 0.26-0.36Mpa and the temperature is controlled at 160-177°C.

[0040] Step 4: The alkaline steam is divided into two parts, with the volume ratio of part one to part two being 1:2. Part one is directly recycled into the ammonia recovery tower after condensation, and part two provides a heat source for the evaporator, and then mixes with the steam flowing out of the evaporator and enters the separator together. The pressure of the evaporator is controlled at (-0.075)-(-0.04)Mpa, and the temperature is controlled at 120-150°C.

[0041] Step 5: The separator separates the water vapor and ammonia, the ammonia enters the ammonia recovery tower for recovery, and the vapor re-enters the neutralization reactor as cooling water after condensation.

[0042] Step 6: The adsorption device separates the condensate into desalted water and concentrated water, and the concentrated water is passed into the neutralization reactor as cooling water; nitric acid is passed into the ammonia recovery tower, and is neutralized with ammonia to form cooling water, which is passed into the bottom of the neutralizer;

[0043] Step seven, the mass fraction of the ammonium nitrate solution flowing out of the neutralization reactor is 79.23%, and it enters the evaporator for concentration. The mass fraction of the concentrated ammonium nitrate solution is 91-93%. After concentration, it enters the intermediate tank to obtain a high-quality ammonium nitrate solution.

[0044] Step eight, treating the prepared high-quality ammonium nitrate solution according to the analytical method of GB / T 9741-2008 "General method for determination of ignition residues in the presence of chemical reagents", and the result is that the ignition residue is ≤ 0.01%.

[0045] It can be seen that the ammonium nitrate solution produced by the technical solution of the present invention has high quality and stable properties, and has a high safety factor during production, transportation and use.

[0046] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing an ammonium nitrate solution, characterized in that: The following steps are involved: Step 1, passing the dilute nitric acid solution through a dechlorination tower, a bleaching tower and a nitric acid filter in sequence, so that the chloride ion content in the dilute nitric acid solution is less than 10.0 mg / kg, the nitrogen oxide content is less than 20.0 mg / kg, and the iron ion content is less than 1.0 mg / kg, to obtain a finished dilute nitric acid solution; Step 2, introducing ammonia gas and finished dilute nitric acid solution into a neutralization reactor, and introducing cooling water into the bottom of the neutralization reactor; Step 3, in a neutralization reactor, the finished dilute nitric acid solution and ammonia gas form an ammonium nitrate solution, and the ammonia gas and water vapor are mixed to form alkaline steam; Step 4: the alkaline steam is divided into two parts, part one is directly condensed and enters the ammonia recovery tower for recovery, and part two provides heat source for the evaporator, and then mixes with the steam flowing out of the evaporator and enters the separator together; Step 5: The separator separates the steam and ammonia, the ammonia enters the ammonia recovery tower for recovery, and the steam condenses to form a condensate that enters the adsorption device; Step 6: The adsorption device separates the condensate into desalted water and concentrated water, and the concentrated water is passed into the neutralization reactor as cooling water; nitric acid is passed into the ammonia recovery tower, and is neutralized with ammonia to form cooling water, which is passed into the bottom of the neutralizer; Step seven, the ammonium nitrate solution enters the evaporator for concentration, and the mass fraction of the concentrated ammonium nitrate solution is 91-93%. After the concentration is completed, it enters the intermediate tank to obtain a high-quality ammonium nitrate solution.

2. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: The mass fraction of the dilute nitric acid solution in step 1 is 58-65%.

3. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: The dechlorination tower in step 1 is a plate-type dechlorination tower, and the dechlorination time is > 2h / layer; the secondary air volume of the bleaching tower is 9000-12000Nm 3 / h, the nanofiltration membrane accuracy of the nitric acid filter is ≤2nm.

4. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: Step 2 also includes heating the liquid ammonia to evaporate it into ammonia gas, filtering it, continuing to heat it, and then introducing it into the neutralization reactor.

5. The method for producing an ammonium nitrate solution according to claim 4, characterized in that: Heat liquid ammonia to 10-15°C and ammonia gas to 60-90°C.

6. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: The acid-ammonia ratio of ammonia gas and dilute nitric acid introduced in step 2 is 7.0-7.5, and the acid-ammonia ratio is (m 酸 +m 氨 ) / m 氨 .

7. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: The temperature of the cooling water in step 2 is 80-95°C.

8. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: The pressure of the neutralization reactor in step 3 is 0.26-0.36Mpa, and the temperature is 160-177°C.

9. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: The volume ratio of part one to part two in step four is 1:(1-3).

10. The method for producing an ammonium nitrate solution according to claim 1, characterized in that: The evaporator in step 4 is a vacuum evaporator with a pressure of (-0.075)-(-0.04)Mpa and a temperature of 120-150°C.

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