Urea-to-ammonia load automatic adjusting device based on hydrolysis technology

Abstract

The utility model discloses a hydrolysis technology-based urea ammonia production load automatic adjusting device, which comprises a urea hydrolysis reactor, a urea solution supply pipeline, a demineralized water supply pipeline, a steam heating coil and a product gas pipeline are arranged on the urea hydrolysis reactor in a connecting manner, and the steam heating coil comprises an inlet pipeline and an outlet pipeline. A heating part of the steam heating coil pipe is arranged in the urea hydrolysis reactor, a sensor assembly is arranged in the urea hydrolysis reactor, a urea solution regulating valve is arranged on the urea solution supply pipeline, a steam regulating valve is arranged on an inlet pipeline of the steam heating coil pipe, a desalted water supply valve is arranged on the desalted water supply pipeline, and a water outlet pipeline of the steam heating coil pipe is provided with a water outlet valve. And a product gas supply regulating valve is arranged on the product gas pipeline. The device disclosed by the utility model can adjust the operation condition of the urea hydrolysis reactor in time under the condition of load change, adjust the urea solution supply quantity according to the ammonia injection requirement of a unit, ensure stable continuous supply, and have the characteristics of rapid reaction and high automation.

Description

Technical Field

[0001] The utility model belongs to the technical field of flue gas denitration reducing agent system control, and in particular relates to a urea ammonia production load automatic adjustment device based on hydrolysis technology. Background Art

[0002] In the system for denitrification of flue gas, selective catalytic reduction (SCR) is the most widely used denitrification technology. Selective catalytic reduction denitrification technology uses ammonia as a reducing agent to reduce nitrogen oxides to nitrogen and water that are harmless to the environment under the action of a catalyst. Ammonia has a high removal efficiency for nitrogen oxide components in flue gas, especially nitric oxide. The preparation methods of ammonia include evaporation of liquid ammonia, evaporation of ammonia water, and hydrolysis / pyrolysis of urea. Since liquid ammonia and ammonia water are flammable and explosive, they are dangerous chemicals and have high requirements for transportation and storage. Relatively speaking, urea is safe, stable, non-toxic, and easier to transport and store. Therefore, urea hydrolysis to produce ammonia has been more widely used in practice. The urea hydrolysis process mainly involves heating the urea solution to hydrolyze urea into ammonia and carbon dioxide, and the ammonia obtained by hydrolysis is used for flue gas denitrification.

[0003] Due to the complex and changeable denitrification conditions, the existing process equipment often has the situation that the control system does not respond in time and the load cannot be adjusted automatically. The untimely response of the control system will lead to deviations in the ammonia production of urea hydrolysis, thus affecting the denitrification efficiency. In order to cope with the changes in the combustion conditions of the unit, it is necessary to adjust the output of the urea hydrolysis reactor in real time to ensure that the operating conditions of the urea hydrolysis reactor are stable and the output meets the needs of the denitrification system. The key factor in controlling the hydrolysis reaction rate is the reaction temperature in the urea hydrolysis reactor. Therefore, it is necessary to adjust the load during the operation of the urea hydrolysis system, conduct further optimization, increase the automatic input rate, and reduce the operating cost. Utility Model Content

[0004] In view of the above-mentioned problems, the utility model provides an automatic load adjustment device for urea production of ammonia based on hydrolysis technology, which solves technical problems such as deviation in urea hydrolysis ammonia production caused by the untimely response of the control system and the inability to automatically adjust in existing process devices.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A urea-ammonia load automatic adjustment device based on hydrolysis technology comprises a urea hydrolysis reactor, the urea hydrolysis reactor is connected with a urea solution supply pipeline, a desalted water supply pipeline, a steam heating coil and a product gas pipeline, the steam heating coil comprises an inlet pipeline and an outlet pipeline, a heating part of the steam heating coil is arranged inside the urea hydrolysis reactor, and is used to provide a heat source for the urea hydrolysis reaction, a sensor component is arranged inside the urea hydrolysis reactor, a urea solution regulating valve is arranged on the urea solution supply pipeline, a steam regulating valve is arranged on the inlet pipeline of the steam heating coil, a desalted water supply valve is arranged on the desalted water supply pipeline, and a product gas supply regulating valve is arranged on the product gas pipeline.

[0007] Furthermore, the sensor assembly includes a temperature sensor, a pressure sensor and a liquid level sensor.

[0008] Furthermore, the temperature sensor, pressure sensor, liquid level sensor, urea solution regulating valve, steam regulating valve, desalted water supply valve and product gas supply regulating valve are all connected to a DCS control system.

[0009] Furthermore, the urea solution regulating valve, steam regulating valve, desalted water supply valve and product gas supply regulating valve are respectively connected to the valve PID automatic adjustment system for adjusting the valve opening, and the valve opening of the urea solution regulating valve, steam regulating valve and product gas supply regulating valve is automatically adjusted through the target quantity SP setting value.

[0010] Furthermore, a sensor assembly arranged inside the urea hydrolysis reactor, a urea solution regulating valve arranged on the urea solution supply pipeline, a steam regulating valve arranged on the inlet pipeline of the steam heating coil, a desalted water supply valve arranged on the desalted water supply pipeline, and a product gas supply regulating valve arranged on the product gas pipeline together constitute an automatic adjustment feedback system, and the sensor assembly and valves are all connected to the DCS control system.

[0011] The utility model discloses an automatic load adjustment device for urea-ammonia production based on hydrolysis technology, and an automatic adjustment method thereof, comprising the following steps:

[0012] S1: When the system is already in operation, it enters the low-load ammonia injection mode through the automatic mode. In the automatic mode, the temperature of the urea hydrolysis reactor is judged. If the temperature of the urea hydrolysis reactor is 115℃≤t≤135℃, and the temperature state remains unchanged after a delay of 60s, it will enter the next step. If not, it will switch to manual. After entering the next step, keep the steam control valve, urea solution control valve, and product gas supply control valve in the open state, and put the valve PID into automatic adjustment. The steam control valve adjusts the pressure of the urea hydrolysis reactor, and the target amount SP=0.55Mpa; the urea solution control valve adjusts the liquid level of the urea hydrolysis reactor, and the target amount SP=700mm; the product gas supply control valve adjusts the ammonia steam outlet pressure of the urea hydrolysis reactor, and the target amount SP=0.4Mpa; At this point, the system enters the low-load ammonia injection mode and supplies ammonia normally;

[0013] S2: When the system is already in operation, it enters the high-load ammonia injection mode through the automatic mode. In the automatic mode, the temperature of the urea hydrolysis reactor is judged. If the temperature of the urea hydrolysis reactor t≥142℃ and the system is in the low-load ammonia injection mode, the temperature state remains unchanged after a delay of 60s, and then the next step is entered. If not, it is transferred to manual. After entering the next step, the steam regulating valve, urea solution regulating valve, and product gas supply regulating valve are kept in the open state, and the valve PID automatic adjustment is put into operation. The steam regulating valve regulates the pressure of the urea hydrolysis reactor, and the target amount SP=0.55Mpa; the urea solution regulating valve regulates the liquid level of the urea hydrolysis reactor, and the target amount SP=800mm; the product gas supply regulating valve regulates the ammonia steam outlet pressure of the urea hydrolysis reactor, and the target amount SP=0.4Mpa; at this point, the system enters the high-load ammonia injection mode and supplies ammonia normally.

[0014] Furthermore, in steps S1 and S2, the set values ​​of pressure, temperature and liquid level target amount SP can be partially adjusted according to actual conditions.

[0015] Furthermore, in steps S1 and S2, the low-load ammonia injection mode or the high-load ammonia injection mode can be entered manually or automatically, and the logical relationship between the manual entry and automatic entry modes is "or".

[0016] Compared with the prior art, the utility model discloses an automatic load adjustment device for urea production of ammonia based on hydrolysis technology, which combines a DCS control system and valve PID automatic adjustment. It can timely adjust the operating conditions of the urea hydrolysis reactor when the load changes, and adjust the supply of urea solution according to the ammonia injection needs of the unit to ensure continuous and stable supply. It has the characteristics of rapid response and high automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of the utility model device;

[0018] Figure 2 This is a schematic diagram of the system control of the utility model device (low load mode);

[0019] Figure 3 This is a schematic diagram of the control system of the utility model device (high load mode);

[0020] In the figure: 1. Urea hydrolysis reactor; 2. Urea solution supply pipeline; 3. Desalted water supply pipeline; 4. Product gas pipeline; 5. Urea solution regulating valve; 6. Steam regulating valve; 7. Desalted water supply valve; 8. Product gas supply regulating valve; 9. Steam heating coil. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the utility model.

[0022] like Figure 1 As shown, the utility model of the urea ammonia load automatic adjustment device based on the hydrolysis technology includes a urea hydrolysis reactor 1, a urea solution supply pipeline 2, a desalted water supply pipeline 3, a steam heating coil 9, a product gas pipeline 4, a urea solution regulating valve 5, a steam regulating valve 6, a desalted water supply valve 7, and a product gas supply regulating valve 8; the desalted water supply pipeline 3 is provided with a desalted water supply valve 7, which is connected to the urea hydrolysis reactor 1 to supply desalted water; the steam heating coil 9 is placed in the urea hydrolysis reactor 1, and after entering the steam, it provides a heat source for the urea hydrolysis reaction, and the steam heating coil 9 has an inlet and outlet pipeline, and a steam regulating valve 6 is provided on the inlet pipeline. The automatic adjustment function is realized by the temperature, pressure, and liquid level sensors inside the urea hydrolysis reactor 1, as well as the urea solution regulating valve 5, the steam regulating valve 6, the desalted water supply valve 7, and the product gas supply regulating valve 8. The sensors and valves are connected to the DCS system for control.

[0023] The urea solution regulating valve 5, the steam regulating valve 6, the desalted water supply regulating valve 7 and the product gas supply regulating valve 8 are respectively connected to the valve PID automatic regulating system, which is used to automatically adjust the valve opening of the urea solution regulating valve 5, the steam regulating valve 6 and the product gas supply regulating valve 8 according to the target quantity SP setting value.

[0024] The output of the urea hydrolysis reactor of the utility model is passively regulated. When the load of the unit changes and the ammonia demand of the denitration system increases, the opening of the ammonia supply regulating valve of the denitration system increases, the pressure in the product gas pipeline 4 decreases, and the opening of the product gas supply regulating valve 8 is automatically increased under PID control to keep the pressure of the product gas pipeline 4 at the set value. At this time, the pressure of the urea hydrolysis reactor 1 will decrease, and the opening of the steam regulating valve 6 will be automatically increased under PID control to increase the steam supply, increase the temperature in the urea hydrolysis reactor 1, and increase the ammonia production rate; vice versa.

[0025] The utility model discloses an automatic load adjustment device for urea-ammonia production based on hydrolysis technology, and an automatic adjustment method thereof, comprising the following steps:

[0026] S1. The system enters the low-load ammonia injection mode when it is already running. It can use manual entry and automatic entry modes. The logical relationship between the two modes is "or". In the automatic mode, the temperature of the urea hydrolysis reactor 1 is judged. If the temperature of the urea hydrolysis reactor 1 is 115℃≤t≤135℃ and maintained for 60s, it enters the low-load ammonia injection mode. If not, it maintains the original state. After entering the next step, keep the steam regulating valve 6, urea solution regulating valve 5, and product gas supply regulating valve 8 in the open state, and put the valve PID into automatic adjustment. The steam regulating valve 6 PID adjustment object is the urea hydrolysis reactor 1 pressure, and the target amount SP=0.55Mpa; the urea solution regulating valve 5 adjusts the urea hydrolysis reactor 1 liquid level, and the target amount SP=700mm; the product gas supply regulating valve 8 adjusts the ammonia steam outlet pressure of the urea hydrolysis reactor 1, and the target amount SP=0.4Mpa. At this point, the system enters the low-load ammonia injection mode and supplies ammonia normally.

[0027] S2. The system enters the high-load ammonia injection mode when it is already running. It can use manual entry and automatic entry modes. The logical relationship between the two modes is "or". In the automatic mode, the temperature of the urea hydrolysis reactor is judged. If the temperature of the urea hydrolysis reactor t≥142℃ is maintained for 60s and the system is in the low-load ammonia injection mode, it will enter the next step. If not, it will remain in the original state. After entering the next step, keep the steam regulating valve 6, urea solution regulating valve 5, and product gas supply regulating valve 8 in the open state, and put the valve PID into automatic adjustment. The steam regulating valve 6 PID adjustment object is the urea hydrolysis reactor 1 pressure, and the target amount SP=0.55Mpa; the urea solution regulating valve 5 adjusts the urea hydrolysis reactor 1 liquid level, and the target amount SP=800mm; the product gas supply regulating valve 8 adjusts the urea hydrolysis reactor 1 ammonia steam outlet pressure, and the target amount SP=0.4Mpa. At this point, the system enters the high-load ammonia injection mode and supplies ammonia normally.

[0028] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. An automatic load adjustment device for urea-ammonia production based on hydrolysis technology, characterized in that: The invention comprises a urea hydrolysis reactor (1), wherein the urea hydrolysis reactor (1) is connected to a urea solution supply pipeline (2), a desalted water supply pipeline (3), a steam heating coil (9) and a product gas pipeline (4), wherein the steam heating coil (9) comprises an inlet pipeline and an outlet pipeline, and a heating portion of the steam heating coil (9) is disposed inside the urea hydrolysis reactor (1) and is used to provide a heat source for the urea hydrolysis reaction. A sensor assembly is disposed inside the urea hydrolysis reactor (1), a urea solution regulating valve (5) is disposed on the urea solution supply pipeline (2), a steam regulating valve (6) is disposed on the inlet pipeline of the steam heating coil (9), a desalted water supply valve (7) is disposed on the desalted water supply pipeline (3), and a product gas supply regulating valve (8) is disposed on the product gas pipeline (4).

2. The automatic load adjustment device for urea-to-ammonia production based on hydrolysis technology according to claim 1 is characterized in that: The sensor assembly includes a temperature sensor, a pressure sensor and a liquid level sensor.

3. The automatic load adjustment device for urea-to-ammonia production based on hydrolysis technology according to claim 2 is characterized in that: The temperature sensor, pressure sensor, liquid level sensor, urea solution regulating valve (5), steam regulating valve (6), desalted water supply valve (7) and product gas supply regulating valve (8) are all connected to a DCS control system.

4. The automatic load adjustment device for urea-to-ammonia production based on hydrolysis technology according to claim 3 is characterized in that: The urea solution regulating valve (5), the steam regulating valve (6), the desalted water supply valve (7) and the product gas supply regulating valve (8) are respectively connected to the valve PID automatic regulating system for regulating the valve opening.

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