阅读说明：本技术 一种尿素水解制氨系统及其控制方法 (Urea hydrolysis ammonia production system and control method thereof ) 是由 张晓远 韦松伟 赵万宝 高鹏 杨海波 赵楠 陈忠平 阎亮 郝佳乐 高丽晶 于 2021-05-17 设计创作，主要内容包括：本发明公开了一种尿素水解制氨系统,包括尿素溶解系统和尿素水解系统,尿素溶解系统包括溶解罐和储罐,尿素水解系统包括水解器,溶解罐的进料口连通与卸料罐车；溶解罐的进水口通过阀门连接疏水泵,疏水泵连接在水箱上；溶解罐上连接有再循环阀,再循环阀连通储罐进液口；溶解罐的排液口连接有溶解泵,溶解泵通过阀门连接储罐；溶解罐上还设有冲洗机构；储罐通过控制阀门组连通在水解器,水解器还通过阀门连通水箱；水解器上设有回流口和排污口；水解器顶部通过调节阀连接氨气脱硝机构；水解器通过阀门组连通蒸汽供给机构。本系统可实现智能化参数设定,可对制氨系统进行自动化精准控制,降低人工成本,避免误操作的风险。(The invention discloses a urea hydrolysis ammonia production system, which comprises a urea dissolving system and a urea hydrolysis system, wherein the urea dissolving system comprises a dissolving tank and a storage tank, the urea hydrolysis system comprises a hydrolyzer, and a feed inlet of the dissolving tank is communicated with a discharge tank car; the water inlet of the dissolving tank is connected with a drain pump through a valve, and the drain pump is connected to the water tank; the dissolving tank is connected with a recirculation valve which is communicated with a liquid inlet of the storage tank; a liquid outlet of the dissolving tank is connected with a dissolving pump, and the dissolving pump is connected with a storage tank through a valve; the dissolving tank is also provided with a flushing mechanism; the storage tank is communicated with the hydrolyzer through a control valve group, and the hydrolyzer is also communicated with the water tank through a valve; the hydrolyzer is provided with a return port and a drain outlet; the top of the hydrolyzer is connected with an ammonia denitration mechanism through a regulating valve; the hydrolyzer is communicated with the steam supply mechanism through a valve group. The system can realize intelligent parameter setting, can automatically and accurately control the ammonia production system, reduces the labor cost and avoids the risk of misoperation.)

1. The utility model provides a urea hydrolysis ammonia production system, includes urea dissolving system and urea hydrolysis system, urea dissolving system is including the dissolving tank of dissolving the urea granule and the storage tank of storage urea solution, and urea hydrolysis system is including the hydrolyzer of urea solution of hydrolysising, its characterized in that: a stirrer and a first liquid level meter are arranged in the dissolving tank, and an exhaust fan is arranged at an exhaust hole in the top of the dissolving tank; the feed inlet of the dissolving tank is communicated with a discharge tank car through a urea particle inlet valve; a water inlet of the dissolving tank is connected with a drain pump through a water inlet valve of the dissolving tank, and the drain pump is connected to a water tank for storing demineralized water; the dissolving tank is also communicated with a recirculation valve through a densimeter, and the recirculation valve is communicated with a storage tank inlet valve arranged at an inlet of the storage tank; the liquid outlet of the dissolving tank is connected with a dissolving pump, and the dissolving pump is connected with an inlet valve of the storage tank through an outlet valve of the dissolving pump; the dissolving tank is also provided with a flushing mechanism;

the liquid outlet of the storage tank is communicated with the liquid inlet of the hydrolyzer through a urea solution control valve group, and the liquid inlet of the hydrolyzer is also communicated with the water tank through a demineralized water inlet valve; the reflux port of the hydrolyzer is communicated with the storage tank through a liquid phase reflux valve, and the drain outlet is communicated with an external drain pipeline; an ammonia discharge outlet at the top of the hydrolyzer is connected with an ammonia gas denitration mechanism through an ammonia vapor outlet regulating valve; a temperature sensor, a pressure sensor and a second liquid level meter are arranged in the hydrolyzer, and a steam inlet is communicated with a steam supply mechanism through a steam regulating valve set.

2. The urea hydrolysis ammonia production system of claim 1, wherein: the flushing mechanism comprises a flushing valve, and the flushing valve connected with the drainage pump is connected between the dissolving pump and the dissolving pump outlet valve.

3. The urea hydrolysis ammonia production system of claim 2, wherein: the urea solution control valve group comprises an inlet shutoff valve and an inlet regulating valve, and a liquid outlet of the storage tank is communicated with a liquid inlet of the hydrolyzer through the inlet shutoff valve and the inlet regulating valve in sequence.

4. The urea hydrolysis ammonia production system of claim 3, wherein: the steam regulating valve group comprises a steam inlet regulating valve and a steam inlet valve, and the steam inlet of the hydrolyzer is communicated with the steam supply mechanism through the steam inlet regulating valve and the steam inlet valve in sequence.

5. The method of controlling a urea hydrolysis ammonia production system according to claim 4, wherein: including urea dissolution control and urea hydrolysis control.

6. The control method according to claim 5, characterized in that: the urea dissolution control specifically comprises starting operation, water supplementing operation, liquid preparation operation, conveying operation and flushing operation; wherein the content of the first and second substances,

the starting operation comprises the following steps: closing a desalted water inlet valve, a dissolving tank water inlet valve, a dissolving pump outlet valve, a flushing valve and a reflux valve of the hydrolyzer;

and water replenishing operation: when the first liquid level meter in the dissolving tank detects that the liquid level is less than the low liquid level threshold value, opening a water inlet valve of the dissolving tank, starting a drain pump to supplement water, and stopping the drain pump and closing the water inlet valve of the dissolving tank when the liquid level is greater than the low liquid level threshold value; after the water replenishing is completed, namely the system monitors that the drain pump stops and the water inlet valve of the dissolving tank is closed, starting the stirrer, opening the recirculation valve, and carrying out stirring and dissolving operation;

the liquid preparation operation comprises the following steps: the system controls the action of an exhaust fan on the dissolving tank, opens a urea particle inlet valve and opens a discharge valve of a discharge tank car; pumping the urea solution into a dissolving tank through a dissolving pump and then sequentially through a recirculation valve and a densimeter, dissolving and continuing the circulating process until the liquid level in the dissolving tank is greater than a high liquid level threshold value and the solution density is greater than a target density, circulating the urea solution for a certain time, finishing unloading, and closing a corresponding valve;

the conveying operation comprises the following steps: after the stirring and dissolving operation is finished, opening an inlet valve of the storage tank and an outlet valve of the dissolving pump, closing a recirculation valve of the dissolving tank, and conveying the urea solution into the storage tank through the action of the dissolving pump; when the liquid level of the dissolving tank is smaller than the low liquid level threshold value or the liquid level of the storage tank is larger than the high liquid level threshold value, the dissolving pump is closed, and the conveying is finished;

the washing operation comprises the following steps: starting a drain pump, opening a flushing valve, a dissolving pump outlet valve and a storage tank inlet valve, closing a recirculation valve, flushing a conveying pipeline from a dissolving tank to a storage tank, and directly pumping the flushed solution into the storage tank; then opening a recirculation valve, closing an inlet valve of the storage tank, flushing a recirculation pipeline of the dissolving tank, and directly pumping the flushed dissolving solution into the dissolving tank to be used as water required for next dissolving; and after the washing is finished, stopping the water delivery pump, and closing all valves of the dissolving tank.

7. The control method according to claim 5, characterized in that: the urea hydrolysis control comprises the processes of filling, preheating, preparing ammonia injection and ammonia injection, and the implementation steps specifically comprise:

closing the inlet shutoff valve, the liquid phase reflux valve and the steam inlet valve, and adjusting the steam inlet adjusting valve, the inlet adjusting valve and the ammonia steam outlet adjusting valve to zero positions;

when the second liquid level meter detects that the liquid level in the hydrolyzer is greater than a set threshold value, the system automatically jumps to the filling process of filling the urea solution; if the liquid level in the hydrolyzer is less than a set threshold value, opening a demineralized water inlet valve, and performing supplementary demineralized water operation on the hydrolyzer; until the liquid level in the hydrolyzer is greater than a set threshold value, the system automatically closes the demineralized water inlet valve; then opening an inlet shutoff valve, and setting an inlet regulating valve at 100%; when the liquid level of the hydrolyzer is greater than the upper limit value, closing the inlet shutoff valve, and setting the inlet regulating valve to 0 percent;

after the inlet shutoff valve is closed, if the pressure of the hydrolyzer is less than the minimum pressure value, the system controls to automatically open the steam inlet valve, and meanwhile, the hydrolyzer selects a temperature control mode and sets a steam inlet regulating valve into an automatic mode; after the valve position signal is in place, setting the temperature value of the hydrolyzer to be 40 ℃, automatically opening a steam inlet adjusting valve to perform heating adjustment, continuously heating for a period of time, continuously increasing the set temperature of the hydrolyzer for a period of time, continuing the heating mode until the temperature is increased to 115 ℃, and maintaining for a period of time, then automatically entering a pressure control mode by the system;

after entering a pressure control mode, the hydrolyzer continuously generates pressure until the pressure is greater than a maximum set value, all regulating valves of the hydrolyzer are set to be in an automatic mode, and the system enters an ammonia spraying preparation mode;

and entering an ammonia spraying mode, automatically opening an ammonia steam outlet regulating valve, a steam inlet regulating valve, an inlet shutoff valve and an inlet regulating valve by the system, regulating a pressure set value, a liquid level set value and an ammonia steam outlet pressure set value into an ammonia spraying mode set value by the system, and automatically regulating the opening and closing degree of each valve by the system according to the set values.

Technical Field

The invention belongs to the field of comfort and urea ammonia production, and particularly relates to a urea hydrolysis ammonia production system and a control method thereof.

Background

The existing urea ammonia production system has large misoperation risk from urea dissolution and storage to frequent local operation of equipment and manual regulation and control of valve action and opening and closing degree by urea hydrolysis operators.

The urea solution preparation district is manual valve on spot more, and urea solution hydrolysis part is installed the remote control valve but needs the manual judgement to every process, and most operation all need be operated to the scene, has taken the maloperation risk, increases operation operating personnel's manual input simultaneously. And the ammonia is toxic gas, and the workman is detained the operation workshop for a long time, can produce very big influence to healthy, and occupational disease risk coefficient increases, and the cost of labor drops into great.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide a urea hydrolysis ammonia production system, which can realize intelligent parameter setting, can automatically and accurately control the ammonia production system, reduce the labor cost and avoid the risk of misoperation.

In order to achieve the purpose, the invention adopts the technical scheme that:

a urea hydrolysis ammonia production system comprises a urea dissolving system and a urea hydrolysis system, wherein the urea dissolving system comprises a dissolving tank for dissolving urea particles and a storage tank for storing urea solution, the urea hydrolysis system comprises a hydrolyzer for hydrolyzing urea solution, a stirrer and a first liquid level meter are arranged in the dissolving tank, and an exhaust fan is arranged at an exhaust hole in the top of the dissolving tank; the feed inlet of the dissolving tank is communicated with a discharge tank car through a urea particle inlet valve; a water inlet of the dissolving tank is connected with a drain pump through a water inlet valve of the dissolving tank, and the drain pump is connected to a water tank for storing demineralized water; the dissolving tank is also communicated with a recirculation valve through a densimeter, and the recirculation valve is communicated with a storage tank inlet valve arranged at an inlet of the storage tank; the liquid outlet of the dissolving tank is connected with a dissolving pump, and the dissolving pump is connected with an inlet valve of the storage tank through an outlet valve of the dissolving pump; the dissolving tank is also provided with a flushing mechanism;

the liquid outlet of the storage tank is communicated with the liquid inlet of the hydrolyzer through a urea solution control valve group, and the liquid inlet of the hydrolyzer is also communicated with the water tank through a demineralized water inlet valve; the reflux port of the hydrolyzer is communicated with the storage tank through a liquid phase reflux valve, and the drain outlet is communicated with an external drain pipeline; an ammonia discharge outlet at the top of the hydrolyzer is connected with an ammonia gas denitration mechanism through an ammonia vapor outlet regulating valve; a temperature sensor, a pressure sensor and a second liquid level meter are arranged in the hydrolyzer, and a steam inlet is communicated with a steam supply mechanism through a steam regulating valve set.

Preferably, the flush mechanism includes a flush valve connected to the hydrophobic pump and connected between the dissolving pump and the dissolving pump outlet valve.

Preferably, the urea solution control valve group comprises an inlet shutoff valve and an inlet regulating valve, and a liquid outlet of the storage tank is communicated with the liquid inlet of the hydrolyzer through the inlet shutoff valve and the inlet regulating valve in sequence.

Preferably, the steam regulating valve set comprises a steam inlet regulating valve and a steam inlet valve, and the steam inlet of the hydrolyzer is communicated with the steam supply mechanism through the steam inlet regulating valve and the steam inlet valve in sequence.

Correspondingly, the invention also provides a control method of the urea hydrolysis ammonia production system, which comprises urea dissolution control and urea hydrolysis control.

The urea dissolution control specifically comprises starting operation, water supplementing operation, liquid preparation operation, conveying operation and flushing operation;

the starting operation comprises the following steps: closing a desalted water inlet valve, a dissolving tank water inlet valve, a dissolving pump outlet valve, a flushing valve and a reflux valve of the hydrolyzer;

and water replenishing operation: when the first liquid level meter in the dissolving tank detects that the liquid level is less than the low liquid level threshold value, opening a water inlet valve of the dissolving tank, starting a drain pump to supplement water, and stopping the drain pump and closing the water inlet valve of the dissolving tank when the liquid level is greater than the low liquid level threshold value; after the water replenishing is completed, namely the system monitors that the drain pump stops and the water inlet valve of the dissolving tank is closed, starting the stirrer, opening the recirculation valve, and carrying out stirring and dissolving operation;

the liquid preparation operation comprises the following steps: the system controls the action of an exhaust fan on the dissolving tank, opens a urea particle inlet valve and opens a discharge valve of a discharge tank car; pumping the urea solution into a dissolving tank through a dissolving pump and then sequentially through a recirculation valve and a densimeter, dissolving and continuing the circulating process until the liquid level in the dissolving tank is greater than a high liquid level threshold value and the solution density is greater than a target density, circulating the urea solution for a certain time, finishing unloading, and closing a corresponding valve;

the conveying operation comprises the following steps: after the stirring and dissolving operation is finished, opening an inlet valve of the storage tank and an outlet valve of the dissolving pump, closing a recirculation valve of the dissolving tank, and conveying the urea solution into the storage tank through the action of the dissolving pump; when the liquid level of the dissolving tank is smaller than the low liquid level threshold value or the liquid level of the storage tank is larger than the high liquid level threshold value, the dissolving pump is closed, and the conveying is finished;

the washing operation comprises the following steps: starting a drain pump, opening a flushing valve, a dissolving pump outlet valve and a storage tank inlet valve, closing a recirculation valve, flushing a conveying pipeline from a dissolving tank to a storage tank, and directly pumping the flushed solution into the storage tank; then opening a recirculation valve, closing an inlet valve of the storage tank, flushing a recirculation pipeline of the dissolving tank, and directly pumping the flushed dissolving solution into the dissolving tank to be used as water required for next dissolving; and after the washing is finished, stopping the water delivery pump, and closing all valves of the dissolving tank.

The urea hydrolysis control comprises the processes of filling, preheating, preparing ammonia injection and ammonia injection, and the implementation steps specifically comprise:

1) closing the inlet shutoff valve, the liquid phase reflux valve and the steam inlet valve, and adjusting the steam inlet adjusting valve, the inlet adjusting valve and the ammonia steam outlet adjusting valve to zero positions;

2) when the second liquid level meter detects that the liquid level in the hydrolyzer is greater than a set threshold value, the system automatically jumps to the filling process of filling the urea solution; if the liquid level in the hydrolyzer is less than a set threshold value, opening a demineralized water inlet valve, and performing supplementary demineralized water operation on the hydrolyzer; until the liquid level in the hydrolyzer is greater than a set threshold value, the system automatically closes the demineralized water inlet valve; then opening an inlet shutoff valve, and setting an inlet regulating valve at 100%; when the liquid level of the hydrolyzer is greater than the upper limit value, closing the inlet shutoff valve, and setting the inlet regulating valve to 0 percent;

3) after the inlet shutoff valve is closed, if the pressure of the hydrolyzer is less than the minimum pressure value, the system controls to automatically open the steam inlet valve, and meanwhile, the hydrolyzer selects a temperature control mode and sets a steam inlet regulating valve into an automatic mode; after the valve position signal is in place, setting the temperature value of the hydrolyzer to be 40 ℃, automatically opening a steam inlet adjusting valve to perform heating adjustment, continuously heating for a period of time, continuously increasing the set temperature of the hydrolyzer for a period of time, continuing the heating mode until the temperature is increased to 115 ℃, and maintaining for a period of time, then automatically entering a pressure control mode by the system;

4) after entering a pressure control mode, the hydrolyzer continuously generates pressure until the pressure is greater than a maximum set value, all regulating valves of the hydrolyzer are set to be in an automatic mode, and the system enters an ammonia spraying preparation mode;

5) and entering an ammonia spraying mode, automatically opening an ammonia steam outlet regulating valve, a steam inlet regulating valve, an inlet shutoff valve and an inlet regulating valve by the system, regulating a pressure set value, a liquid level set value and an ammonia steam outlet pressure set value into an ammonia spraying mode set value by the system, and automatically regulating the opening and closing degree of each valve by the system according to the set values.

The invention has the following beneficial effects:

according to the urea hydrolysis ammonia production system, the intelligent control operation of urea hydrolysis ammonia production is realized by accurately regulating and controlling each valve, and the safe and stable operation of the urea dissolving and urea solution hydrolysis system is ensured.

The intelligent control of the urea hydrolysis ammonia production system ensures the safe and stable operation of the urea dissolving and urea solution hydrolysis systems, further realizes the one-key start-stop function in the two processes of urea conveying, dissolving, urea solution storage and urea solution hydrolysis, realizes the accurate control by the parameter setting of the intelligent control, and prevents the risk of misoperation. A large amount of human input cost is saved, misoperation risks caused by frequent operation of personnel are reduced, and the risk of ammonia poisoning when the personnel operate on the spot is avoided.

Drawings

FIG. 1 is a schematic diagram of a urea dissolving system of the present invention;

FIG. 2 is a schematic diagram of a urea hydrolysis system of the present invention;

FIG. 3 is a schematic diagram of a urea dissolution control system according to the present invention;

FIG. 4 is a schematic diagram of a urea hydrolysis control system according to the present invention.

Detailed Description

The invention provides a urea hydrolysis ammonia production system, which comprises a urea dissolving system and a urea hydrolysis system, wherein the urea dissolving system comprises a dissolving tank 3 for dissolving urea particles and a storage tank 5 for storing urea solution, and the urea hydrolysis system comprises a hydrolyzer 6 for hydrolyzing the urea solution.

As shown in fig. 1, a stirrer 32 and a first liquid level meter 34 are arranged in the dissolving tank 3, and an exhaust fan 33 is arranged at an exhaust hole at the top; the feed inlet of the dissolving tank 3 is communicated with the discharging tank car 2 through a urea particle inlet valve 21; the water inlet of the dissolving tank 3 is connected with a drain pump 11 through a dissolving tank water inlet valve 31, and the drain pump 11 is connected to a water tank 1 for storing desalted water. The demineralized water pipeline of the water tank 1 is divided into two paths, one path enters the hydrolyzer 6 and the other path reaches the dissolving tank 3, each branch is provided with a corresponding valve, and the valve of the branch is automatically opened by controlling to correspondingly convey demineralized water through the pipeline. The dissolving tank 3 is also communicated with a recirculation valve 36 through a density meter 35, and the recirculation valve 36 is communicated with a storage tank inlet valve 51 arranged at an inlet of the storage tank 5. The dissolving pump 4 is connected to the drain port of the dissolving tank 3, and the dissolving pump 4 is connected to the reservoir inlet valve 51 through the dissolving pump outlet valve 41 and to the drain pump 11 through the flush valve 42 of the flush mechanism, respectively.

As shown in FIG. 2, the liquid outlet of the storage tank 5 is communicated with the liquid inlet of the hydrolyzer 6 through an inlet shutoff valve 64 and an inlet regulating valve 66 in turn, and the liquid inlet of the hydrolyzer 6 is also communicated with the water tank 1 through a desalted water inlet valve 67. The reflux port of the hydrolyzer 6 is communicated with the storage tank 5 through a liquid phase reflux valve 65, and the pressure is released when the pressure in the hydrolyzer 6 is overhigh. Wherein, the liquid phase reflux valve 65 is automatically opened when the pressure of the hydrolyzer 6 is more than 1.05Mpa, and the reflux port is communicated with the storage tank 5 through the liquid phase reflux valve 65 to carry out the pressure relief of the hydrolyzer 6. The drain is communicated with an external drain pipeline. An ammonia discharge outlet at the top of the hydrolyzer 6 is connected with an ammonia denitration mechanism through an ammonia steam outlet regulating valve 61. A temperature sensor, a pressure sensor and a second liquid level meter are arranged in the hydrolyzer 6, and a steam inlet is communicated with a steam supply mechanism through a steam inlet regulating valve 62 and a steam inlet valve 63 in sequence.

According to the urea hydrolysis ammonia production system, the intelligent control operation of urea hydrolysis ammonia production is realized by accurately regulating and controlling each valve, and the safe and stable operation of the urea dissolving and urea solution hydrolysis system is ensured.

Correspondingly, as shown in fig. 3-4, the invention also provides a control method based on the urea hydrolysis ammonia production system, which comprises urea dissolution control and urea hydrolysis control.

The urea dissolving control comprises a manual mode, a semi-automatic mode and a full-automatic mode, and the different modes comprise operations such as starting operation, water supplementing operation, liquid preparation operation, conveying operation, flushing operation and the like. Wherein, the urea dissolving system can be provided with two dissolving devices comprising a dissolving tank 3, a pump body and a storage tank 5, the two devices are independent batching systems, and the step sequence is controlled by one system. Before the system is operated, a dissolving tank 3, a pump body and a storage tank 5 corresponding to the dissolving device are selected.

In the semi-automatic mode, the liquid preparation, the conveying and the flushing are independent and can be executed independently.

In the full-automatic mode, from stopping to conveying, the user only needs to manually trigger a starting button, select the needed dissolving tank 3 and select to convey the urea solution to the needed storage tank 5, and the solution is automatically cleaned after being conveyed. And then realize carrying, dissolving from urea, store to urea solution, two processes of urea solution hydrolysis realize the key and open the start-stop function again, through intelligent control's parameter setting, realized accurate control, prevent the risk of maloperation. A large amount of human input cost is saved, misoperation risks caused by frequent operation of personnel are reduced, and the risk of ammonia poisoning when the personnel operate on the spot is avoided.

Wherein the start-up operation: closing the desalted water inlet valve 67, the dissolving tank water inlet valve 31, the dissolving pump outlet valve 41, the flushing valve 42 and the return valve 65 on the hydrolyzer 6;

water replenishing operation: after the system judges that all valve position signals are normal, when a first liquid level meter 34 in the dissolving tank 3 detects that the liquid level is smaller than a low liquid level threshold value of 1400mm, a water inlet valve 31 of the dissolving tank is opened, and a drain pump 11 is started to supplement water; stopping the operation of the drainage pump 11 and closing the water inlet valve 31 of the dissolving tank until the liquid level is more than the low liquid level threshold value of 1400 mm; after the water replenishing is completed, namely the system monitors that the drain pump 11 stops and the water inlet valve 31 of the dissolving tank is closed, the stirrer 32 is started, the recirculation valve 36 is opened, and the stirring and dissolving operation is carried out. The system activates the dissolving pump 4 and opens the dissolving pump outlet valve 41 after a period of time, which indicates that urea can be removed, by monitoring the agitator 32 operating signal and the recirculation valve 36 open signal.

Liquid preparation operation: the system controls the action of an exhaust fan on the dissolving tank 3, and at the moment, the system has liquid distribution conditions, opens the urea particle inlet valve 21 and opens the discharge valve of the discharge tank truck 2. The material of the discharge tanker 2 is guided into the dissolving tank 3, and the material conveying process lasts for 40 minutes. After the materials enter the dissolving tank 3, the urea solution is pumped into the dissolving tank 3 through the dissolving pump 4, the recirculation valve 36 and the densimeter 35 in sequence, the dissolving operation is continued in the circulation process until the liquid level in the dissolving tank is more than the high liquid level threshold value and the solution density is more than the target density 1140kg/m³After that, the urea solution is circulated for 120 seconds, i.e. the discharge is completed.

Conveying operation: after the stirring and dissolving operation is completed, opening the inlet valve 51 of the storage tank and the outlet valve 41 of the dissolving pump, closing the recirculation valve 36 of the dissolving tank 3, and conveying the urea solution into the storage tank 5 through the action of the dissolving pump 4; when the liquid level of the dissolving tank 3 is less than the low liquid level threshold value or the liquid level of the storage tank 5 is greater than the high liquid level threshold value, the dissolving pump 4 is closed, the conveying is displayed to be finished, and the dissolving pump 4 can be manually stopped in the process if an emergency situation occurs.

Washing operation: after the transportation is finished, the drain pump 11 is automatically started, the flushing valve 42, the dissolving pump outlet valve 41 and the storage tank inlet valve 51 are opened, and the recirculation valve 36 is closed, wherein the process lasts for 5 minutes, and the transportation pipeline from the dissolving tank 3 to the storage tank 5 can be effectively flushed. The flushed solution is directly injected into the storage tank 5, the urea solution after being dissolved is not influenced because the storage capacity of the storage tank 5 is large, after 5 minutes, the recirculation valve 36 is opened, the inlet valve 51 of the storage tank 5 is closed, the process lasts for 10 minutes, and the recirculation pipeline of the dissolving tank 3 can be flushed. The solution after washing is directly injected into the dissolving tank 3 as water for next dissolving. And after the washing is finished, stopping the water delivery pump, and closing all valves of the dissolving tank 3.

The urea dissolving and conveying are completed completely, the urea dissolving and conveying can be performed in a semi-automatic mode or a manual mode, and each step can be completed only by clicking a corresponding button by an operator.

The urea hydrolysis system corresponding to the urea hydrolysis control in the invention consists of 3 hydrolyzers, and the control logic of the hydrolyzers is optimized, so that the intelligent operation and operation of cold-state and hot-state starting and process control are realized.

The urea hydrolysis control is in an automatic control operation mode, and the control system enables the hydrolysis system to automatically fill, preheat, prepare for ammonia injection and inject ammonia under the condition of no operator intervention as long as an operator presses a start button. The operation steps specifically comprise:

1) closing the inlet shutoff valve 64, the liquid phase return valve 65 and the steam inlet valve 63 for conveying the urea solution, and simultaneously adjusting the steam inlet adjusting valve 62, the urea solution inlet adjusting valve 66 and the ammonia steam outlet adjusting valve 61 to zero positions, and starting the manual mode.

2) After the valve signal is in place, when the second liquid level meter detects that the liquid level in the hydrolyzer 6 is more than 0.51m, the system automatically jumps to the filling process of filling the urea solution.

If the liquid level in the hydrolyzer 6 is less than 0.51m, the demineralized water inlet valve 67 is automatically opened, and the hydrolyzer 6 carries out the operation of supplementing demineralized water; until the liquid level in the hydrolyzer 6 is more than 0.51m, the system will automatically close the demineralized water inlet valve 67. Then the inlet shutoff valve 64 is opened while the urea inlet regulator valve 66 is set to 100%; when the liquid level of the hydrolyzer 6 is more than 0.85m, the urea solution inlet shutoff valve 64 is closed, and the urea solution inlet regulating valve 66 is set to 0 percent.

3) And (3) closing the urea solution inlet shutoff valve 64, and after the signal of the regulating valve is in place, if the pressure of the hydrolyzer 6 is less than 0.3Mpa, automatically opening the steam inlet valve 63 by the system control, and simultaneously, selecting a temperature control mode by the hydrolyzer 6 to set the steam inlet regulating valve 62 to be an automatic mode.

After the valve position signal is in place, setting the temperature value of the hydrolyzer 6 to be 40 ℃, automatically opening the steam inlet adjusting valve 62 for heating adjustment, setting the temperature to be 70 ℃ after 5 minutes, continuously heating for 5 minutes until the temperature is raised to 115 ℃, maintaining for 10 minutes, automatically entering a pressure control mode by the system, setting the pressure to be 0.3Mpa, and then entering an ammonia spraying preparation mode by the system.

4) After entering the pressure control mode, the hydrolyzer 6 continues to generate pressure until the pressure is greater than 0.55Mpa, all the regulating valves of the hydrolyzer 6 are set to be in an automatic mode, and the system enters an ammonia spraying preparation mode.

5) And entering an ammonia spraying mode, automatically opening an ammonia steam outlet regulating valve 61, a steam inlet regulating valve 62, an inlet shutoff valve 64 and an inlet regulating valve 66 by the system, automatically setting the pressure to be 0.55Mpa, setting the liquid level to be 0.85m and setting the pressure of an ammonia steam outlet to be 0.35Mpa by the system. The system will automatically adjust the opening and closing degree of each valve according to the set value.

Meanwhile, the emergency stop and normal stop buttons are arranged in the system for preventing emergency situations during operation, and once a crisis situation occurs, an operator can manually trigger the buttons to perform safety protection on the hydrolyzer 6.

In addition, the urea hydrolysis control can also be carried out in a semi-automatic mode and a manual mode, and each step can be completed only by clicking a corresponding button by an operator.

The intelligent control of the urea hydrolysis ammonia production system ensures the safe and stable operation of the urea dissolving and urea solution hydrolysis system, solves the safety risk of frequent operation of operators, saves a large amount of manpower and saves the cost. Through intelligent module parameter setting, realized accurate control, prevent the risk of maloperation, prevent the safety risk of personnel's scene poisoning.