A denitration urea ammonia water hydrolyzer operation control system

Abstract

The utility model discloses a kind of denitration urea ammonia hydrolyzer operation control systems, including parallelly arranged hydrolysis reactor one and hydrolysis reactor two and corresponding denitration generator set one and denitration generator set two. Among them, hydrolysis reactor one ammonia outlet is connected denitration generator set one by the ammonia supply main pipeline one configured with outlet valve one, and hydrolysis reactor two ammonia outlet is connected denitration generator set two by the ammonia supply main pipeline two equipped with outlet valve two;And two sets of ammonia supply main pipeline are provided with the communication pipe of two-way fluid communication, the pipeline is configured with intelligent isolation valve, and the opening and closing state of medium conveying passage can be accurately regulated and controlled. The system is through load response mechanism, based on denitration generator set real-time load parameter, and intelligently selects single machine or double machine operation mode, and realizes the flexible switching of "point to point" independent ammonia supply or "cross system" joint ammonia supply between hydrolysis reactor and generator set by the valve collaborative control.

Description

Technical Field

[0001] This utility model belongs to the field of flue gas denitrification engineering technology, specifically relating to an SCR denitrification system operation control device based on urea hydrolysis to produce ammonia, which is applicable to nitrogen oxide emission reduction systems in coal-fired power plants and industrial boilers. Background Technology

[0002] SCR denitrification technology mainly uses liquid ammonia, ammonia water, or urea as a reducing agent to produce ammonia gas. The denitrification reduction reaction is carried out under the action of a catalyst. Among them, the liquid ammonia evaporation method is the cheapest in terms of investment, transportation, and usage costs. However, the liquid ammonia system has significant safety hazards, and safety accidents are common. The ammonia water system has high investment, operation, and transportation costs. It is safer than liquid ammonia, but still has certain safety hazards. The urea system has higher investment and operation costs than the liquid ammonia system, but the transportation costs are comparable. Moreover, the urea system has virtually no safety hazards and is the safest ammonia production technology.

[0003] Urea solution is heated and pressurized in a hydrolyzer to decompose into ammonia and carbon dioxide. Existing urea hydrolysis ammonia production systems mostly operate under fixed configurations, which have the following drawbacks:

[0004] 1. The delayed response of ammonia supply regulation during load fluctuations affects denitrification efficiency;

[0005] 2. Redundant equipment configuration leads to excessive energy consumption;

[0006] 3. Switching between operating modes requires manual intervention, which poses an operational risk;

[0007] 4. Backup equipment cannot maintain a hot standby state, and restarting it is time-consuming and energy-intensive;

[0008] To address the above issues, a solution is proposed below. Utility Model Content

[0009] This invention addresses the technical limitations of existing urea hydrolysis ammonia production systems by proposing an operation control system with dynamic load response capability and intelligent switching function. By constructing a collaborative operation mechanism of dual hydrolysis reactors, it achieves disturbance-free switching and energy efficiency optimization of the ammonia supply system.

[0010] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0011] A control system for a denitrified urea-to-ammonia hydrolyzer includes a hydrolysis reactor 1, a denitrification generator set 1, a hydrolysis reactor 2, and a denitrification generator set 2. The ammonia outlets of the hydrolysis reactor 1 and the hydrolysis reactor 2 are connected to the denitrification generator set 1 and the denitrification generator set 2 respectively via ammonia supply pipeline 1 and ammonia supply pipeline 2. The ammonia supply pipeline 1 and the ammonia supply pipeline 2 are connected by a flexible switching module to form a bidirectional fluid communication loop. The flexible switching module includes a connecting pipe installed between the two pipelines, and the connecting pipe is equipped with an isolation regulating valve for dynamically adjusting and controlling the pipeline connection status. Both the hydrolysis reactor 1 and the hydrolysis reactor 2 are equipped with a load response control module and a heat standby maintenance device.

[0012] Furthermore, both the ammonia supply pipeline one and the ammonia supply pipeline two are integrated with pressure relief branch pipes, and pressure relief control valves are installed on the pressure relief branch pipes and connected to steam purging devices.

[0013] Furthermore, both the first and second hydrolysis reactors are connected to the urea tank via urea solution supply pipelines; the urea solution supply pipelines are equipped with urea solution inlet valves at their ends, and urea solution circulation loops are connected in parallel on the urea solution supply pipelines.

[0014] Furthermore, the heat standby maintenance device includes a de-temperature and pressure reduction integrated device, and the hydrolysis reactor is connected to the corresponding de-temperature and pressure reduction integrated device through a steam transmission pipeline, the end of which is equipped with a steam inlet valve.

[0015] Furthermore, a heat tracing device is connected to the connecting pipe.

[0016] Furthermore, both the ammonia outlet sections of the hydrolysis reactor one and the hydrolysis reactor two are equipped with outlet valves.

[0017] Furthermore, the load response control module utilizes the load-ammonia supply coupling algorithm and the feedforward compensation mechanism for the switching process built into the DCS industrial control system.

[0018] A control method for the operation control system of a denitrified urea ammonia hydrolyzer, which adopts dual-mode operation control, including single-machine operation control mode and dual-machine operation control mode.

[0019] When the unit load is less than or equal to the preset threshold, a single-unit operation control mode is adopted, selecting one hydrolysis reactor as the main operating hydrolysis reactor and the other as a standby hydrolysis reactor; the ammonia supply load between the two units is dynamically transferred through regulating valves, and the standby hydrolysis reactor remains in a hot standby state; the specific steps are as follows:

[0020] S1: Check the heat tracing of the connecting pipe between the two sets of hydrolysis reactors;

[0021] S2: The NOx concentration at the outlet of the denitrification reactor of the two sets of denitrification generator units is controlled below the design value, and stable operation is maintained at a time threshold not lower than the preset time threshold.

[0022] S3: Open the isolation regulating valve between the two hydrolysis reactors;

[0023] S4: The two hydrolysis reactors operate in parallel. The ammonia supply to the standby hydrolysis reactor is reduced according to the actual operating conditions, while the ammonia supply to the main operating hydrolysis reactor is increased.

[0024] S5: Close the steam inlet valve, urea solution inlet valve, and outlet valve of the standby hydrolysis reactor to maintain hot standby status. The ammonia vapor generated by the main hydrolysis reactor is used to power the two denitrification generator sets.

[0025] When the unit load exceeds the preset threshold, the single-unit operation control mode will be switched to the dual-unit operation control mode, with both hydrolyzers operating independently and NOx concentration monitored in real time; a pre-condition judgment mechanism for mode switching will be established; the specific steps are as follows:

[0026] S1: Open the steam inlet valve and urea solution inlet valve of the standby hydrolysis reactor to increase the temperature and pressure of the hydrolyzer to the set value;

[0027] S2: The inlet and outlet NOx concentrations of the two sets of denitrification generator reactors are controlled below the design value, and stable operation is maintained at a time threshold not lower than the set value.

[0028] S3: Open the outlet valve on the standby hydrolysis reactor;

[0029] S4: The two hydrolysis reactors operate in parallel. The ammonia supply to the main hydrolysis reactor is gradually reduced according to the actual operating conditions, while the ammonia supply to the standby hydrolysis reactor is increased.

[0030] S5: Close the isolation regulating valve between the two hydrolysis reactors, and control the corresponding denitrification generator set of each set of hydrolysis reactors.

[0031] The beneficial effects of this utility model are as follows:

[0032] 1) This utility model system is based on the design of a bidirectional fluid communication loop. With the help of the valves, it can achieve flexible switching between "point-to-point" independent ammonia supply and "cross-system" joint ammonia supply between the hydrolysis reactor and the generator set, and realize single-machine or dual-machine operation mode.

[0033] 2) In this utility model, the operating mode can be intelligently selected according to the real-time load of the denitrification generator set. Under low load, only one hydrolysis reactor needs to supply ammonia to two units, reducing redundant equipment operation and reducing energy consumption. Through the setting of the hot standby maintenance device, the standby reactor is kept in hot standby state, avoiding the energy consumption of reheating and pressurizing during cold start. Through the load-ammonia supply coupling algorithm and feedforward compensation mechanism, the ammonia supply and demand are matched in real time, reducing energy waste caused by excessive ammonia supply.

[0034] 3) In this utility model, the flexible switching based on the mode enables single-machine operation under low load, reducing the number of start-ups and shutdowns, avoiding frequent equipment switching, and reducing mechanical wear and thermal stress accumulation; the integrated pressure relief branch pipe and steam purging device on the ammonia supply pipeline can prevent damage to the equipment caused by excessive pressure or pipeline blockage; and the system parameters are kept stable through valve regulation and pressure gradient control, reducing the risk of equipment overload.

[0035] 4) In this utility model, the standby reactor is kept in a hot standby state and can be started quickly, which improves emergency efficiency; the connecting pipeline and intelligent isolation valve support undisturbed flexible switching, ensuring the continuity of ammonia supply. Attached Figure Description

[0036] Figure 1 This is a system diagram for an embodiment;

[0037] Figure 2 This is a schematic diagram of the structure of the hydrolysis reactor in Example 1;

[0038] Figure 3 This is a schematic diagram of the structure of the second hydrolysis reactor in the embodiment.

[0039] Figure 4 This is a schematic diagram of the logic control of the load response control module.

[0040] Figure reference numerals: 1. Hydrolysis reactor one; 11. Ammonia supply pipeline one; 2. Hydrolysis reactor two; 21. Ammonia supply pipeline two; 3. Flexible switching module; 4. Pressure relief pipe; 5. Urea solution inlet pipe; 6. Urea solution return pipe; 7. Steam inlet pipe; 8. Desuperheating and pressure reducing device; 9. Steam purging device; 10. Heat standby maintenance device; 12. Heat tracing device; 13. Isolation regulating valve; 14. Denitrification generator set one; 15. Denitrification generator set two; 16. Load response control module. Detailed Implementation

[0041] The following description is merely a preferred embodiment of this utility model, and the scope of protection is not limited to this embodiment. All technical solutions falling within the scope of this utility model's concept should be protected. Identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "bottom" and "top," "inner" and "outer" refer to directions toward or away from the geometric center of a specific component.

[0042] like Figures 1 to 4 As shown, a denitrification urea-to-ammonia hydrolyzer operation control system includes a hydrolysis reactor 1, a denitrification generator set 1, a hydrolysis reactor 2, and a denitrification generator set 2. The two denitrification generator sets have identical structures; the denitrification generator sets are a series of devices in the SCR or SCNR process, excluding the ammonia supply mechanism, such as boilers and SCR / SCNR reactors. When both denitrification generator sets are operating at high load, the two hydrolysis reactors provide energy one-to-one; when both denitrification generator sets are operating at low load, one of the hydrolysis reactors is selected to provide energy.

[0043] The ammonia outlet of hydrolysis reactor 1 is connected to denitrification generator set 1 via ammonia supply pipeline 11, and is equipped with outlet valve 1. The ammonia outlet of hydrolysis reactor 1 is connected to denitrification generator set 2 via ammonia supply pipeline 21, and is equipped with outlet valve 2. The two hydrolysis reactors have the same structure and operation. Taking hydrolysis reactor 1 as an example, the ammonia generated in hydrolysis reactor 1 is transported to denitrification generator set 1 via the ammonia supply pipeline.

[0044] Both hydrolysis reactor 1 and hydrolysis reactor 2 are connected to a urea solution inlet pipe 5 and a steam inlet pipe 7. The urea solution inlet pipe 5 and the steam inlet pipe 7 are used to transport raw materials into the corresponding hydrolysis reactors. A urea solution inlet valve is provided at the end of the urea solution inlet pipe 5, and a steam inlet valve is provided at the end of the steam inlet pipe 7. The two valves can regulate the feed rate of the raw materials.

[0045] A urea solution return pipe 6 is also connected to the urea solution inlet pipe 5. Urea solution is drawn from the urea tank, passed through the urea solution inlet pipe 5, and transported to the hydrolysis reactor. The liquid level of the reaction liquid in the urea hydrolyzer is set, and the opening of the urea solution supply valve is adjusted via PID control to regulate the supply rate in real time. The supply rate of urea solution is also controlled by the valve settings on the urea solution inlet pipe 5.

[0046] The steam inlet pipe 7 is also equipped with a de-cooling and de-pressure device 8, which can cool and depressurize the steam input into the hydrolysis reactor to meet the requirements.

[0047] Both ammonia supply pipeline 11 and ammonia supply pipeline 21 are equipped with pressure relief pipes 4, each with a pressure relief valve. If the gas pressure inside hydrolysis reactor 1 or hydrolysis reactor 2 is too high, the pressure can be released through the pressure relief pipes 4 and the pressure relief valves, protecting the safety of hydrolysis reactor 1 and hydrolysis reactor 2. To ensure safety, a steam purging device 9 is installed on the pressure relief pipes 4, which is periodically purged to keep the pressure relief pipes 4 unobstructed.

[0048] A flexible switching module 3 is installed between ammonia supply pipeline 11 and ammonia supply pipeline 21. The flexible switching module 3 includes a connecting pipe installed between the two ammonia supply pipelines, with both pipelines 11 and 21 connected to it. An isolation valve is installed inside the connecting pipe. When the isolation valve is open, both hydrolysis reactors can supply ammonia to the other denitrification generator set; when the isolation valve is closed, each hydrolysis reactor can only supply ammonia to its corresponding denitrification generator set. For safety, a heat tracing device 12 is connected to the connecting pipe to keep it unobstructed.

[0049] Both hydrolysis reactors are equipped with a load response control module and a hot standby maintenance device. The hot standby maintenance device includes a steam microcirculation loop and a pressure gradient maintenance unit. In this embodiment, the hot standby maintenance device includes a steam inlet pipe 7 and a desuperheating and pressure reducing device 8. The load response control module incorporates a load-ammonia supply coupling algorithm and a feedforward compensation mechanism for the switching process.

[0050] The working principle of the system in this embodiment is as follows:

[0051] The system comprises two sets of symmetrically structured hydrolysis reaction units. Taking hydrolysis reactor 1 as an example: This reactor receives a urea solution with a concentration of 40%–60% through urea solution supply pipeline 5, and generates an NH3 / CO2 mixed gas through the hydrolysis reaction. Steam supply pipeline 7 provides saturated steam at 0.6–1.2 MPa, which is adjusted to 0.4–0.6 MPa and 130–160°C by the desuperheating and pressure reducing integrated device 8 before being fed into the reactor.

[0052] The dual-mode operation control logic is as follows:

[0053] Mode 1: Hydrolysis reactor 1 switches to a one-to-two operation mode (the principle for switching hydrolysis reactor 2 to a one-to-two operation mode is the same).

[0054] When the unit load is less than or equal to the preset threshold, the system automatically selects the main operating hydrolyzer; the ammonia supply load between the two units is dynamically transferred through the regulating valve, and the standby hydrolyzer is kept in hot standby mode (temperature 120℃-130℃, pressure 0.3MPa-0.4MPa).

[0055] S1: The heat tracing of the connecting pipe between the two hydrolysis reactors was checked and found to be normal.

[0056] S2: The NOx concentration at the outlet of the denitrification reactor of the two sets of denitrification generator units is controlled below the design value and maintained stable operation for no less than 30 minutes;

[0057] S3: Open the isolation regulating valve 13 between hydrolysis reactor 1 and hydrolysis reactor 2;

[0058] S4: Hydrolysis reactor 1 and hydrolysis reactor 2 operate in parallel. The ammonia supply of hydrolysis reactor 2 is gradually reduced according to the actual operating conditions, while the ammonia supply of hydrolysis reactor 1 is increased. If the ammonia supply of hydrolysis reactor 1 cannot meet the operating requirements of denitrification generator unit 2 during the switching process, the ammonia supply of hydrolysis reactor 2 needs to be increased.

[0059] S5: Close the steam inlet valve, urea solution inlet valve, and outlet valve 2 of hydrolysis reactor 2 to maintain hot standby status. The ammonia vapor generated by the reaction of hydrolysis reactor 1 is used by the two denitrification generator sets.

[0060] Mode 2: One-to-one operation.

[0061] When the unit load exceeds the preset threshold, the two hydrolyzers operate independently; NOx concentration is monitored in real time (set value ≤ 50 mg / Nm³). 3 Establish a precondition judgment mechanism for mode switching (requires stable operation for ≥30 minutes).

[0062] When preparing to increase boiler load:

[0063] S1: Open the steam inlet valve and urea solution inlet valve of hydrolysis reactor 2 to increase the temperature and pressure of the hydrolyzer to the set value;

[0064] S2: The inlet and outlet NOx concentrations of the two sets of denitrification generator reactors are controlled below the design value and maintained stable operation for no less than 30 minutes;

[0065] S3: Open outlet valve 2 on hydrolysis reactor 2;

[0066] S4: Hydrolysis reactor 1 and hydrolysis reactor 2 operate in parallel. The ammonia supply of hydrolysis reactor 1 is gradually reduced according to the actual operating conditions, while the ammonia supply of hydrolysis reactor 2 is increased. If the ammonia supply of hydrolysis reactor 2 cannot meet the operating requirements of denitrification generator unit 2 during the switching process, the ammonia supply of hydrolysis reactor 1 needs to be increased.

[0067] S5: Close the isolation valves between hydrolysis reactor 1 and hydrolysis reactor 2, and the two sets of hydrolysis reactors and the two sets of denitrification generator sets will operate one-to-one.

[0068] In this embodiment, the load response control module consists of:

[0069] 1. Load-Ammonia Supply Algorithm Unit (Multi-channel PID): Real-time monitoring of generator set load, automatic calculation and adjustment of ammonia supply.

[0070] 2. Feedforward compensation unit: Predicts and eliminates system fluctuations (such as pressure changes) during mode switching.

[0071] 3. Valve controller: Precisely controls pipeline valves (such as isolation valves and steam valves) to ensure synchronized switching.

[0072] 4. Sensor module: Monitors parameters such as pressure, temperature, and flow rate to ensure safe operation.

[0073] 5. Communication interface: Connects to the control system (DCS) to receive commands and provide feedback data.

[0074] 6. Intelligent operation mode: Automatically switches between "one-to-one" or "one-to-two" ammonia supply modes according to the load level (such as 60% or 75% of the rated value) to ensure stable NOx concentration.

[0075] In this embodiment, the system achieves the following functions through a load response control module:

[0076] 1. The hot standby maintenance device includes a steam micro-circulation loop (flow rate ≥ 200 kg / h) and a pressure gradient control system (ΔP ≤ 0.05 MPa);

[0077] 2. The load-ammonia supply coupling algorithm adopts a feedforward compensation mechanism, with a response time ≤ 5s;

[0078] 3. The DCS system integrates an equipment health status monitoring module to enable preventative maintenance;

[0079] 4. Smooth switching: The switching process is undisturbed, with ammonia pressure fluctuation ≤ ±5% and transfer rate ≤ 5% / min.

[0080] 5. Hot standby rapid start: The standby equipment is maintained at 120-130℃ and 0.3-0.4MPa, which increases the emergency response speed by 3 times.

[0081] The module achieves efficient, stable, and safe automated operation of the denitrification system through intelligent PID regulation, precise valve control, and real-time monitoring.

[0082] Example 1 (Single reactor, dual unit operation mode):

[0083] When the DCS detects that the unit load is ≤60% of the rated value, the following switching procedure is executed:

[0084] S1: Perform status monitoring of the heat tracing system for the inter-reactor connection pipes;

[0085] S2: Ensure that the NOx concentration of the target unit remains stable at 20±5 mg / Nm3 for 30 minutes;

[0086] S3: Activate the isolation valve and establish a dual ammonia supply channel;

[0087] S4: Implement dynamic transfer control of ammonia supply load, with a transfer rate ≤5% / min;

[0088] S5: Close the material channel of the standby unit and maintain the hot standby parameters: temperature 120℃-130℃, pressure 0.3MPa-0.4MPa.

[0089] Example 2 (Dual reactor independent operation mode):

[0090] When the unit load is greater than 75% of the rated value:

[0091] S1: Start the gradient heating program for the backup unit, with a temperature rise rate ≤15℃ / min;

[0092] S2: Establish a dual-system parallel operation transition period of ≥30 min;

[0093] S3: Employ fuzzy control algorithm for cross-regulation of ammonia supply;

[0094] S4: Control ammonia pressure fluctuation to ≤±5% during final switching.

[0095] The specific embodiments described above further illustrate the technical problems, technical solutions, and beneficial effects of this utility model. It should be understood that the above descriptions are merely specific embodiments of this utility model and are not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A control system for a denitrified urea-to-ammonia hydrolyzer, characterized in that: It includes a hydrolysis reactor 1 (1), a denitrification generator set 1 (14), a hydrolysis reactor 2 (2), and a denitrification generator set 2 (15); the ammonia outlets of the hydrolysis reactor 1 (1) and the hydrolysis reactor 2 (2) are connected to the denitrification generator set 1 (14) and the denitrification generator set 2 (15) respectively through ammonia supply pipeline 1 (11) and ammonia supply pipeline 2 (21); the ammonia supply pipeline 1 (11) and the ammonia supply pipeline 2 (21) are connected to form a bidirectional fluid communication loop through a flexible switching module (3), the flexible switching module (3) includes a connecting pipe installed between the two pipelines, and an isolation regulating valve (13) is provided on the connecting pipe for dynamically adjusting and controlling the pipeline connection status; the hydrolysis reactor 1 (1) and the hydrolysis reactor 2 (2) are both equipped with a load response control module and a hot standby maintenance device.

2. The operation control system for the denitrified urea-to-ammonia hydrolyzer according to claim 1, characterized in that, Both the ammonia supply pipeline 1 (11) and the ammonia supply pipeline 2 (21) are equipped with pressure relief branch pipes (4), and pressure relief control valves are installed on the pressure relief branch pipes (4) and connected to steam purging devices (9).

3. The denitration urea ammonia hydrolyzer operation control system according to claim 1, characterized by, Both the first hydrolysis reactor (1) and the second hydrolysis reactor (2) are connected to the urea tank through the urea solution supply pipeline (5); the end of the urea solution supply pipeline (5) is equipped with a urea solution inlet valve, and a urea solution circulation loop (6) is connected in parallel on the urea solution supply pipeline (5).

4. The denitration urea ammonia hydrolyzer operation control system according to claim 1, characterized by, The heat standby device includes a de-temperature and de-pressure integrated device (8). The hydrolysis reactor and the corresponding de-temperature and de-pressure integrated device (8) are connected by a steam transmission pipeline (7). The end of the steam transmission pipeline (7) is equipped with a steam inlet valve.

5. The operating control system for a de-nitrured urea to ammonia hydrolyzer of claim 1, wherein, A heat tracing device (12) is connected to the connecting pipe.

6. The operating control system for a de-nitrured urea to ammonia hydrolyzer of claim 1, wherein, Both the ammonia outlet sections of the hydrolysis reactor one (1) and the hydrolysis reactor two (2) are equipped with outlet valves.

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