阅读说明：本技术 一种料浆法粉状map生产方法 (Method for producing powdery MAP by slurry method ) 是由 项双龙 陈彬 田其富 李金宪 胡黔 杨阳 莫校东 李波 于 2020-11-28 设计创作，主要内容包括：本发明涉及磷酸一铵生产技术领域,具体是一种料浆法粉状MAP生产方法。本申请在目前料浆法生产MAP的基础上,通过一系列改造,旁路设置,改造与现有生产并联使用,随时取样检测中和料浆中和度、比重及流动性,摸索并确定了改进型生产方法及对应的最佳配酸和中和操作等生产参数,最终得到了一种低能耗、蒸汽用量少、生产过程中不易堵管的料浆法粉状MAP生产方法。(The invention relates to the technical field of monoammonium phosphate production, in particular to a method for producing powdery MAP by a slurry method. On the basis of the existing slurry method for producing MAP, the method is used for sampling and detecting the neutralization degree, specific gravity and fluidity of neutralized slurry at any time by using a series of reconstruction and bypass arrangement in parallel with the existing production, finds and determines an improved production method and corresponding optimal acid preparation, neutralization operation and other production parameters, and finally obtains the slurry method for producing the powdery MAP with low energy consumption, less steam consumption and difficult pipe blockage in the production process.)

1. A method for producing powdery MAP by a slurry method is characterized by comprising the following steps:

(1) introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific weight of phosphoric acid in the acid preparation tank to be 1.40-1.50;

(2) after the acid is prepared to the required specific gravity, filtering the concentrated acid after the acid preparation by a filter, and conveying the concentrated acid to an external circulation reactor through an acid supply pipe by using an on-site acid preparation pump;

(3) the neutralization degree of the slurry in the outer circulation reactor is controlled to be 0.95-1.1 or 1.35-1.45, the outer circulation reactor is provided with a condensed water inlet for supplementing steam condensed water and assisting the specific gravity condition of acid preparation, the specific gravity of the neutralized slurry in the outer circulation reactor is regulated and controlled to be 1.45-1.55, the water content of the slurry is 20% -25%, and the reaction temperature of the slurry is 120-135 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, and the reaction evaporation gas phase is finally discharged;

(5) the outer circulation flow reactor is connected with an outer circulation flow circulating pump, two slurry liquid outlet pipes are arranged at the outlet of the outer circulation flow circulating pump, the slurry liquid outlet pipes are provided with heat preservation and steam purging pipelines, after emergency shutdown, slurry liquid outlet pipes and slurry spraying pipes return slurry to be emergently discharged into a ground groove to be diluted and then enter an acid distribution groove, a slurry conveying pipeline is subjected to steam purging replacement, and the slurry liquid outlet pipes are communicated with a material distributor and pumped into a drying powder spraying tower through a three-cylinder pump to spray powder.

2. The slurry process powdered MAP production method according to claim 1, wherein step (2), the filter filtration, in particular using a mesh filter, the mesh size is less than or equal to 8 mm.

3. The slurry process powdered MAP production method according to claim 1, wherein step (2), wherein the acid feed pipe regulates the acid feed rate through a pneumatic valve.

4. The method for producing powdered MAP according to claim 3, wherein the external loop reactor has four gas ammonia pipes around it, and the four gas ammonia pipes around it enter tangentially at the same time to ensure tangential agitation of the ammonium phosphate reaction slurry.

5. The method of producing powdered MAP by slurry process according to claim 1, wherein the slurry neutralization degree is monitored by in-situ sampling monitoring during the control of the slurry neutralization degree in the external loop reactor of step (3).

6. The slurry process powdered MAP production method according to claim 1, wherein in step (4), a pneumatic valve is provided at the end of the outer discharge pipe.

7. The slurry method powdered MAP production method according to claim 1, wherein in the step (4), an electric valve is arranged at the terminal of an outer discharge pipe, and the opening degree is adjusted through the electric valve to control the exhaust amount, so that the pressure balance of a distribution cylinder and the slurry temperature of a neutralization tank are ensured.

8. The method for producing powdered MAP according to the slurry method of claim 1, wherein the slurry outlet pipe of step (5) has a pipe diameter DN 125.

9. The slurry powdered MAP production method according to claim 8, wherein the steam purge line of step (5) has a pipe diameter of DN 80.

Technical Field

The invention relates to the technical field of monoammonium phosphate production, in particular to a method for producing powdery MAP by a slurry method.

Background

The slurry method is to prepare monoammonium phosphate by taking dilute phosphoric acid as a raw material and carrying out neutralization, concentration, slurry spraying and drying.

The current process flow of the slurry method is as follows: 20% -30% of P2O5 phosphoric acid provided by a phosphoric acid plant enters a forced circulation ammoniation reactor to perform neutralization reaction with gas ammonia from an ammonia station. The degree of neutralization is controlled between 0.98 and 1.03, in which range the partial pressure of NH3 of the ammoniated phosphoric acid solution is small. The water content of the dilute ammonium phosphate slurry obtained by neutralization depends on the phosphoric acid content. If the content of the phosphoric acid is 20-28%, the water content of the neutralized slurry is 48-55%. Because the ammonium phosphate slurry is a solution with viscosity greatly changing with temperature and concentration, and in order to save steam consumption, a double-effect concentration process of countercurrent feeding is generally adopted; the first effect adopts normal pressure and fresh steam, the second effect adopts evaporation steam (or called secondary steam) of the first effect as a heater heat source, and vacuum concentration is adopted. The concentrated slurry contains 25-30% of water, the vacuum degree of the second effect is generated by adding cooling water into a mixing condenser and condensing the steam of the second effect. The concentrated ammonium phosphate slurry is pumped to a nozzle of a drying tower by a high-pressure pump, atomized by the high pressure of 4-8Mpa generated by the pump, sprayed into the drying tower, dried with hot air of 120-135 ℃ from a hot blast stove in a counter-current manner, and overflowed from an overflow port at the bottom of the drying tower to enter a belt conveyor to be conveyed to a bulk cargo warehouse. And tail gas generated by the drying tower enters a washing system after gravity settling and dust removal, is washed by water and then is discharged, and washing liquid returns to the system for digestion. The slurry method for producing powdered monoammonium phosphate is still one of the most common methods, such as patent CN201210151672.3 (a method for producing granular monoammonium phosphate).

The prior production process for producing powdery monoammonium phosphate by a slurry method mainly has the following problems:

(1) the traditional slurry method for producing the powdery monoammonium phosphate has high energy consumption, and a one-effect two-effect axial-flow pump needs to be kept on to keep slurry reaction and overcurrent with power of 605 kw.

(2) The traditional slurry method for producing powdery monoammonium phosphate needs to consume a large amount of primary raw steam (the primary raw steam is low-pressure steam entering a one-effect axial-flow pump and is used for concentrating ammonium phosphate slurry), and even if a double-effect concentration flow of countercurrent feeding is adopted to save the steam consumption, a large amount of primary raw steam also needs to be consumed.

(3) The slurry fluidity is not good when the traditional slurry method is used for producing the powdery monoammonium phosphate, and the used production device is frequently blocked.

Therefore, it is urgent to find a slurry method for producing powdery MAP with low energy consumption, less steam consumption and less pipe blockage during the production process.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides

A method for producing powdery MAP by a slurry method comprises the following steps:

(1) introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific weight of phosphoric acid in the acid preparation tank to be 1.40-1.50;

(2) after the acid is prepared to the required specific gravity, the concentrated acid after the acid preparation is filtered by a filter, and an on-site acid preparation pump (the flow is 70 m)³H, head 40m) through the acid feed tube to the external loop reactor;

(3) the neutralization degree of the slurry in the outer circulation reactor is controlled to be 0.95-1.1 or 1.35-1.45, the outer circulation reactor is provided with a condensed water inlet for supplementing steam condensed water and assisting the specific gravity condition of acid preparation, the specific gravity of the neutralized slurry in the outer circulation reactor is regulated and controlled to be 1.45-1.55, the water content of the slurry is 20% -25%, and the reaction temperature of the slurry is 120-135 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, and the reaction evaporation gas phase is finally discharged;

(5) the external circulation flow reactor is connected with the external circulation flow circulating pump, two slurry outlet pipes (one of the two slurry outlet pipes is a spare pipeline) are arranged at the outlet of the external circulation flow circulating pump, the slurry outlet pipes are provided with a heat preservation and steam purging pipeline, after emergency shutdown, the slurry outlet pipes and the slurry spraying pipes (which are the same pipeline and provided with emptying joints) are discharged into the ground groove for emergency dilution of the backflow slurry and then enter the acid distribution groove, the slurry conveying pipes are subjected to steam purging and replacement, and the slurry outlet pipes are communicated with the material distributor and then enter the drying powder spraying tower for powder spraying through the suction of the three-cylinder.

Preferably, in the step (2), the filter is used for filtering, in particular a screen filter is used, and the aperture of the screen is less than or equal to 8 mm.

Preferably, the step (2) is that the acid supply pipe regulates the flow rate of the acid through a pneumatic valve.

Preferably, the outer circulation reactor is provided with four gas ammonia pipelines at the periphery, and the four gas ammonia pipelines at the periphery (DN40/DN50) synchronously enter tangentially, so that the tangential stirring of the ammonium phosphate reaction slurry is ensured.

Preferably, during the control process of the slurry neutralization degree in the external circulation reactor of the step (3), the slurry neutralization degree is monitored by sampling and monitoring in situ.

Preferably, in the step (4), a pneumatic valve is arranged at the terminal of the outer discharge pipe. The pneumatic valve is a valve driven and controlled by compressed air and used for flexibly and accurately fine-adjusting the opening of the valve, and the steam pressure and the reaction temperature of the reaction slurry are adjusted through the opening of the valve.

Preferably, in the step (4), an electric valve is arranged at the terminal of the outer discharge pipe, and the opening degree is adjusted through the electric valve to control the air displacement, so that the pressure balance of the distribution cylinder and the slurry temperature of the neutralization tank are ensured.

Preferably, the slurry outlet pipe in the step (5) has a pipe diameter of DN 125. The pipe diameter is determined according to the material passing amount, and the material passing effect is good.

Preferably, the steam purge line of step (5) has a pipe diameter of DN 80. The pipe diameter is determined according to the material passing amount, and the material passing effect is good.

The method can stop a two-effect axial-flow pump system, and secondary steam generated by neutralization is introduced into a water cooling tower (the water cooling tower is used for generating system vacuum and is a vacuum evaporation system) and is used for liquid ammonia evaporation, and the water cooling tower system ensures that liquid ammonia is gasified and heat exchanged for use.

On the basis of the existing slurry method for producing MAP, the method is used for sampling and detecting the neutralization degree, specific gravity and fluidity of neutralized slurry at any time by using a series of reconstruction and bypass arrangement in parallel with the existing production, finds and determines an improved production method and corresponding optimal acid preparation, neutralization operation and other production parameters, and finally obtains the slurry method for producing the powdery MAP with low energy consumption, less steam consumption and difficult pipe blockage in the production process.

Compared with the prior art, the invention has the technical effects that:

(1) the energy consumption of the production method of the powdery monoammonium phosphate by the traditional slurry method is higher, and by stopping the one-two-effect axial flow pump system, the energy consumption is finally greatly reduced, and after the project is completed, the great comprehensive benefits are brought:

the power consumption can be directly saved every year (the concentrated two-effect axial-flow pump motor is mainly used for stopping the power, and other stopping equipment in the middle process saves the power consumption):

deactivating the one-two effect pump: (250+355) kW × 0.85 × 24h × 330d × 0.5-ary 203.65 ten thousand-ary.

Secondly, the steam consumption can be directly saved every year (compared with the current concentrated acid production process, the current concentrated acid production process is a process for producing by replacing dilute phosphoric acid with concentrated phosphoric acid and ensuring the production of high-concentration products):

15.87m³the/h multiplied by 0.57 (double effect D/W) multiplied by 24h multiplied by 330D multiplied by 40 yuan (based on the production cost of the internal by-product) is 286.60 ten thousand yuan.

(2) The traditional slurry method for producing the powdery monoammonium phosphate needs to consume a large amount of primary steam (the conventional consumption of the primary steam is 12 m)³Per) even if the steam consumption is saved by adopting a double-effect concentration process of countercurrent feeding, a large amount of primary steam still needs to be consumed, the application reduces the steam consumption to 0m by introducing secondary steam generated by neutralization into a water cooling tower (the water cooling tower is used for generating system vacuum and is a vacuum evaporation system) for evaporating liquid ammonia³/h。

(3) The ground paste mobility is not good when likepowder monoammonium phosphate of traditional slurry method production, and the stifled pipe of used apparatus for producing is frequent, and this application further promotes the mobility of ground paste through key conditions such as control complex acid proportion and interior ground paste neutralization degree, promotes production speed, prevents that stifled pipe phenomenon from appearing.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The technical solution of the present invention is further defined below with reference to the specific embodiments, but the scope of the claims is not limited to the description.

Example 1

(1) Introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific gravity of phosphoric acid in the acid preparation tank to be 1.45;

(2) after the acid is prepared to the required specific gravity, filtering the concentrated acid after the acid preparation through a screen filter, wherein the aperture of the screen is 7mm, and utilizing an on-site acid preparation pump (the flow is 70 m)³A head of 40m) was passed through an acid supply tube to the external loop reactor, wherein the acid supply tube regulated the inlet acid flow rate by a pneumatic valve;

(3) four gas ammonia pipelines are arranged around the outer loop reactor, four gas ammonia pipelines (DN40) enter synchronously and tangentially to ensure tangential stirring of ammonium phosphate reaction slurry, the neutralization degree of the slurry in the outer loop reactor is controlled at 1.0, the neutralization degree of the slurry is monitored by on-site sampling monitoring in the reaction process, the outer loop reactor is provided with a condensed water inlet, steam condensed water is supplemented, the condition of the specific gravity of the neutralized slurry in the outer loop reactor is adjusted and controlled to be 1.50, the water content of the slurry is 22.5%, and the reaction temperature of the slurry is 127 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, the reaction evaporation gas phase is finally discharged, and the pneumatic valve is arranged at the terminal of the discharge pipe;

(5) the external circulation flow reactor is connected with an external circulation flow circulating pump, two slurry liquid outlet pipes are arranged at the outlet of the external circulation flow circulating pump, the pipe diameter is DN125 (one of the two slurry liquid outlet pipes is a spare pipe), the slurry liquid outlet pipes are provided with a heat preservation and steam purging pipeline, the pipe diameter is DN80, after emergency shutdown, the slurry liquid outlet pipes and the slurry spraying pipes (which are the same pipe and provided with an emptying joint) are fed into an acid distribution tank after the backflow slurry is diluted in an emergency discharge manner, the slurry conveying pipeline is subjected to steam purging replacement, and the slurry liquid outlet pipes are communicated with each other to enter a distributor and are pumped into a drying powder spraying tower.

Example 2

(1) Introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific gravity of phosphoric acid in the acid preparation tank to be 1.40;

(2) after the acid is prepared to the required specific gravity, filtering the concentrated acid after the acid preparation through a screen filter, wherein the aperture of the screen is 6mm, and utilizing an on-site acid preparation pump (the flow is 70 m)³A head of 40m) was passed through an acid supply tube to the external loop reactor, wherein the acid supply tube regulated the inlet acid flow rate by a pneumatic valve;

(3) four gas ammonia pipelines are arranged around the outer loop reactor, four gas ammonia pipelines (DN40) enter synchronously and tangentially to ensure tangential stirring of ammonium phosphate reaction slurry, the neutralization degree of the slurry in the outer loop reactor is controlled at 0.95, the neutralization degree of the slurry is monitored by on-site sampling monitoring in the reaction process, the outer loop reactor is provided with a condensed water inlet for supplementing steam condensed water and assisting in acid-matching specific gravity condition, the neutralized slurry specific gravity in the outer loop reactor is regulated and controlled to be 1.45, the water content of the slurry is 25%, and the reaction temperature of the slurry is 120 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, the reaction evaporation gas phase is finally discharged, and the pneumatic valve is arranged at the terminal of the discharge pipe;

(5) the external circulation flow reactor is connected with an external circulation flow circulating pump, two slurry liquid outlet pipes are arranged at the outlet of the external circulation flow circulating pump, the pipe diameter is DN125 (one of the two slurry liquid outlet pipes is a spare pipe), the slurry liquid outlet pipes are provided with a heat preservation and steam purging pipeline, the pipe diameter is DN80, after emergency shutdown, the slurry liquid outlet pipes and the slurry spraying pipes (which are the same pipe and provided with an emptying joint) are fed into an acid distribution tank after the backflow slurry is diluted in an emergency discharge manner, the slurry conveying pipeline is subjected to steam purging replacement, and the slurry liquid outlet pipes are communicated with each other to enter a distributor and are pumped into a drying powder spraying tower.

Example 3

(1) Introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific gravity of phosphoric acid in the acid preparation tank to be 1.50;

(2) after the acid is prepared to the required specific gravity, filtering the concentrated acid after the acid preparation through a screen filter, wherein the aperture of the screen filter is 8mm, and utilizing an on-site acid preparation pump (the flow is 70 m)³A head of 40m) was passed through an acid supply tube to the external loop reactor, wherein the acid supply tube regulated the inlet acid flow rate by a pneumatic valve;

(3) four gas ammonia pipelines are arranged around the outer loop reactor, four gas ammonia pipelines (DN50) enter synchronously and tangentially to ensure tangential stirring of ammonium phosphate reaction slurry, the neutralization degree of the slurry in the outer loop reactor is controlled to be 1.1, the neutralization degree of the slurry is monitored by on-site sampling monitoring in the reaction process, the outer loop reactor is provided with a condensed water inlet, steam condensed water is supplemented, the condition of the specific gravity of the neutralized slurry in the outer loop reactor is adjusted and controlled to be 1.55, the water content of the slurry is 20 percent, and the reaction temperature of the slurry is 135 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, the reaction evaporation gas phase is finally discharged, and the pneumatic valve is arranged at the terminal of the discharge pipe;

(5) the external circulation flow reactor is connected with an external circulation flow circulating pump, two slurry liquid outlet pipes are arranged at the outlet of the external circulation flow circulating pump, the pipe diameter is DN125 (one of the two slurry liquid outlet pipes is a spare pipe), the slurry liquid outlet pipes are provided with a heat preservation and steam purging pipeline, the pipe diameter is DN80, after emergency shutdown, the slurry liquid outlet pipes and the slurry spraying pipes (which are the same pipe and provided with an emptying joint) are fed into an acid distribution tank after the backflow slurry is diluted in an emergency discharge manner, the slurry conveying pipeline is subjected to steam purging replacement, and the slurry liquid outlet pipes are communicated with each other to enter a distributor and are pumped into a drying powder spraying tower.

Example 4

(1) Introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific gravity of phosphoric acid in the acid preparation tank to be 1.45;

(2) after the acid is prepared to the required specific gravity, filtering the concentrated acid after the acid preparation through a screen filter, wherein the aperture of the screen is 7mm, and utilizing an on-site acid preparation pump (the flow is 70 m)³H, head 40m) is suppliedAn acid pipe to an external circulation reactor, wherein the acid supply pipe regulates the flow of the acid through a pneumatic valve;

(3) four gas ammonia pipelines are arranged around the outer loop reactor, four gas ammonia pipelines (DN40) enter synchronously and tangentially to ensure tangential stirring of ammonium phosphate reaction slurry, the neutralization degree of the slurry in the outer loop reactor is controlled at 1.40, the neutralization degree of the slurry is monitored by on-site sampling monitoring in the reaction process, the outer loop reactor is provided with a condensed water inlet, steam condensed water is supplemented, the condition of the specific gravity of the neutralized slurry in the outer loop reactor is adjusted and controlled to be 1.50, the water content of the slurry is 22.5%, and the reaction temperature of the slurry is 127 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, the reaction evaporation gas phase is finally discharged, and the terminal of the discharge pipe is provided with an electric valve;

(5) the external circulation flow reactor is connected with an external circulation flow circulating pump, two slurry liquid outlet pipes are arranged at the outlet of the external circulation flow circulating pump, the pipe diameter is DN125 (one of the two slurry liquid outlet pipes is a spare pipe), the slurry liquid outlet pipes are provided with a heat preservation and steam purging pipeline, the pipe diameter is DN80, after emergency shutdown, the slurry liquid outlet pipes and the slurry spraying pipes (which are the same pipe and provided with an emptying joint) are fed into an acid distribution tank after the backflow slurry is diluted in an emergency discharge manner, the slurry conveying pipeline is subjected to steam purging replacement, and the slurry liquid outlet pipes are communicated with each other to enter a distributor and are pumped into a drying powder spraying tower.

Example 5

(1) Introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific gravity of phosphoric acid in the acid preparation tank to be 1.40;

(2) after the acid is prepared to the required specific gravity, filtering the concentrated acid after the acid preparation through a screen filter, wherein the aperture of the screen is 6mm, and utilizing an on-site acid preparation pump (the flow is 70 m)³A head of 40m) was passed through an acid supply tube to the external loop reactor, wherein the acid supply tube regulated the inlet acid flow rate by a pneumatic valve;

(3) four gas ammonia pipelines are arranged around the outer loop reactor, four gas ammonia pipelines (DN40) enter synchronously and tangentially to ensure tangential stirring of ammonium phosphate reaction slurry, the neutralization degree of the slurry in the outer loop reactor is controlled to be 1.35, the neutralization degree of the slurry is monitored by on-site sampling monitoring in the reaction process, the outer loop reactor is provided with a condensed water inlet, steam condensed water is supplemented, the condition of the specific gravity of the neutralized slurry in the outer loop reactor is adjusted and controlled to be 1.45, the water content of the slurry is 25%, and the reaction temperature of the slurry is 120 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, the reaction evaporation gas phase is finally discharged, and the terminal of the discharge pipe is provided with an electric valve;

(5) the external circulation flow reactor is connected with an external circulation flow circulating pump, two slurry liquid outlet pipes are arranged at the outlet of the external circulation flow circulating pump, the pipe diameter is DN125 (one of the two slurry liquid outlet pipes is a spare pipe), the slurry liquid outlet pipes are provided with a heat preservation and steam purging pipeline, the pipe diameter is DN80, after emergency shutdown, the slurry liquid outlet pipes and the slurry spraying pipes (which are the same pipe and provided with an emptying joint) are fed into an acid distribution tank after the backflow slurry is diluted in an emergency discharge manner, the slurry conveying pipeline is subjected to steam purging replacement, and the slurry liquid outlet pipes are communicated with each other to enter a distributor and are pumped into a drying powder spraying tower.

Example 6

(1) Introducing concentrated phosphoric acid into an acid preparation tank, supplementing process water, washing water, ground tank collected water and the like, adjusting and supplementing diluted phosphoric acid according to the condition of product nutrients, and controlling the specific gravity of phosphoric acid in the acid preparation tank to be 1.50;

(2) after the acid is prepared to the required specific gravity, filtering the concentrated acid after the acid preparation through a screen filter, wherein the aperture of the screen filter is 8mm, and utilizing an on-site acid preparation pump (the flow is 70 m)³A head of 40m) was passed through an acid supply tube to the external loop reactor, wherein the acid supply tube regulated the inlet acid flow rate by a pneumatic valve;

(3) four gas ammonia pipelines are arranged around the outer loop reactor, four gas ammonia pipelines (DN50) enter synchronously and tangentially to ensure tangential stirring of ammonium phosphate reaction slurry, the neutralization degree of the slurry in the outer loop reactor is controlled at 1.45, the neutralization degree of the slurry is monitored by on-site sampling monitoring in the reaction process, the outer loop reactor is provided with a condensed water inlet for supplementing steam condensed water and assisting in acid-matching specific gravity condition, the neutralized slurry specific gravity in the outer loop reactor is regulated and controlled to be 1.55, the water content of the slurry is 20%, and the slurry reaction temperature is 135 ℃;

(4) the gas phase pipe of the external loop reactor is communicated with a steam distribution cylinder to balance the steam pressure in the reactor, so that the subsequent gas phase pipe of the steam distribution cylinder is ensured to be smooth, the reaction evaporation gas phase is finally discharged, and the terminal of the discharge pipe is provided with an electric valve;

(5) the external circulation flow reactor is connected with an external circulation flow circulating pump, two slurry liquid outlet pipes are arranged at the outlet of the external circulation flow circulating pump, the pipe diameter is DN125 (one of the two slurry liquid outlet pipes is a spare pipe), the slurry liquid outlet pipes are provided with a heat preservation and steam purging pipeline, the pipe diameter is DN80, after emergency shutdown, the slurry liquid outlet pipes and the slurry spraying pipes (which are the same pipe and provided with an emptying joint) are fed into an acid distribution tank after the backflow slurry is diluted in an emergency discharge manner, the slurry conveying pipeline is subjected to steam purging replacement, and the slurry liquid outlet pipes are communicated with each other to enter a distributor and are pumped into a drying powder spraying tower.

Comparative example 1

The production method is implemented by a traditional slurry method for producing powdery monoammonium phosphate, and specifically comprises the following steps:

20% -30% P from phosphoric acid plant₂O₅Phosphoric acid enters a forced circulation ammoniation reactor to carry out neutralization reaction with gas ammonia from an ammonia station. The neutralization degree is controlled between 0.98 and 1.03, and the water content of the neutralized slurry is between 48 and 55 percent. A double-effect concentration process of countercurrent feeding is adopted; the first effect adopts normal pressure and fresh steam, the second effect adopts evaporation steam (or called secondary steam) of the first effect as a heater heat source, and vacuum concentration is adopted. The concentrated slurry contains 25-30% of water, the vacuum degree of the second effect is generated by adding cooling water into a mixing condenser and condensing the steam of the second effect. The concentrated ammonium phosphate slurry is pumped to a nozzle of a drying tower by a high-pressure pump, atomized by the high pressure of 4-8Mpa generated by the pump, sprayed into the drying tower, dried with hot air of 120-135 ℃ from a hot blast stove in a counter-current manner, and overflowed from an overflow port at the bottom of the drying tower to enter a belt conveyor to be conveyed to a bulk cargo warehouse. And tail gas generated by the drying tower enters a washing system after gravity settling and dust removal, is washed by water and then is discharged, and washing liquid returns to the system for digestion.

Comparative example 2

The production is carried out by a production process of powdery monoammonium phosphate concentrated acid, which comprises the following steps:

40% -50% P from phosphoric acid plant₂O₅Phosphoric acid enters a forced circulation ammoniation reactor to perform neutralization reaction with gas ammonia from an ammonia station, and the fluidity of the phosphoric acid is supplemented with process water according to materials in the reaction process. The neutralization degree is controlled between 0.98 and 1.03, and the water content of the neutralized slurry is between 48 and 55 percent. A double-effect concentration process of countercurrent feeding is adopted; the first effect adopts normal pressure and fresh steam, the second effect adopts evaporation steam (or called secondary steam) of the first effect as a heater heat source, and vacuum concentration is adopted. The concentrated slurry contains 25-30% of water, the vacuum degree of the second effect is generated by adding cooling water into a mixing condenser and condensing the steam of the second effect. The concentrated ammonium phosphate slurry is pumped to a nozzle of a drying tower by a high-pressure pump, atomized by the high pressure of 4-8Mpa generated by the pump, sprayed into the drying tower, dried with hot air of 120-135 ℃ from a hot blast stove in a counter-current manner, and overflowed from an overflow port at the bottom of the drying tower to enter a belt conveyor to be conveyed to a bulk cargo warehouse. And tail gas generated by the drying tower enters a washing system after gravity settling and dust removal, is washed by water and then is discharged, and washing liquid returns to the system for digestion.

The powdered monoammonium phosphate product obtained in each example: nutrient specification: 10(N) -50 (P)₂O₅) -0% and water content less than or equal to 1%, and the obtained product has more stable quality.

And this application is through stopping opening a two-effect axial-flow pump system, and final very big reduction the energy consumption can bring great comprehensive benefit:

comparing with comparative example 1: the power consumption can be directly saved every year (the concentrated two-effect axial-flow pump motor is mainly used for stopping the use, and other stopping equipment in the middle process saves the power consumption):

deactivating the one-two effect pump: (250+355) kW × 0.85 × 24h × 330d × 0.5-ary 203.65 ten thousand-ary.

② compared with the comparative example 2: the steam consumption can be directly saved every year:

15.87m³the/h multiplied by 0.57 (double effect D/W) multiplied by 24h multiplied by 330D multiplied by 40 yuan (based on the production cost of the internal by-product) is 286.60 ten thousand yuan.

Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above-described embodiments, and many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.