Automatic control system of marine methanol boiler and control method thereof

Abstract

The present application provides a kind of methanol boiler automatic control system and control method for ship, and automatic control device is connected combustion fan frequency converter, combustion fan;Automatic control device is also connected combustion air door actuator, atomizing air door actuator;Automatic control device is connected on the ignition pump of exhaust fan, methanol main supply valve for supplying methanol to combustor, methanol delivery pump, 1# methanol cut-off valve, methanol regulating valve, 2# methanol cut-off valve of combustor;Automatic control device is also connected to combustor fuel delivery pump, fuel regulating valve, electric heater, 1# fuel cut-off valve, 2# fuel cut-off valve for supplying fuel;Automatic control device is also connected to water supply pump, water supply regulating valve for supplying water to methanol boiler;Methanol boiler on combustor is connected to automatic control device, and sends start-stop signal;It also includes combustion management system, boiler safety protection system, man-machine interface.The present application can realize that the ship boiler system with methanol or fuel oil as fuel is safe, reliable and stable operation.

Description

Technical Field

[0001] This invention relates to an automatic control system and control method for a marine methanol boiler, used for the automatic control of a methanol-powered auxiliary boiler system in a ship. Background Technology

[0002] New low-carbon and carbon-free fuels will inevitably be widely used in the development of future ships.

[0003] Methanol (CH3OH) contains only one carbon atom, significantly reducing CO2 release during combustion compared to traditional fuels. Furthermore, methanol production technology is mature, and raw materials such as coal, natural gas, biomass, and CO2 can all be used to produce methanol. Therefore, using methanol as the primary fuel is an effective means of achieving carbon neutrality in the marine sector. In the future, methanol boilers will undoubtedly occupy an important position in the marine application market.

[0004] Due to the unique operating environment of marine boilers and the flammable, explosive, volatile, and slightly toxic characteristics of methanol fuel, the performance requirements for controllers are higher than those for conventional products. Programmable Logic Controllers (PLCs) offer advantages such as programmability, high stability, easy expansion, and ease of maintenance, and are widely used in industrial control and marine equipment control systems. Summary of the Invention

[0005] The purpose of this invention is to provide a safe, reliable, and stable automatic control system for marine methanol boilers. It solves the problems of high carbon and NOx emissions associated with traditional boilers. It also addresses the issue of automatically switching fuels in case of methanol fuel mode failure and shutdown.

[0006] The technical solution adopted to achieve the above objectives is

[0007] An automatic control system for a marine methanol boiler includes an automatic control device;

[0008] The automatic control device is connected to the combustion fan frequency converter and the combustion fan; the combustion fan is controlled through the combustion fan frequency converter; the combustion fan supplies air to the combustion damper and the atomizing damper.

[0009] The automatic control device is connected to the combustion damper actuator, which controls the combustion damper of the burner.

[0010] The automatic control device is connected to the atomizing damper actuator, which controls the atomizing damper of the burner.

[0011] The automatic control device is connected to the exhaust fan;

[0012] The automatic control device is connected to the ignition pump on the burner;

[0013] The automatic control device is also connected to the main methanol supply valve, methanol delivery pump, No. 1 methanol shut-off valve, methanol regulating valve, and No. 2 methanol shut-off valve that supply methanol to the burner.

[0014] The automatic control device is also connected to the fuel delivery pump, fuel regulating valve, electric heater, No. 1 fuel shut-off valve, and No. 2 fuel shut-off valve that supply fuel to the burner.

[0015] The automatic control device is also connected to the water supply pump and water supply regulating valve that supply water to the methanol boiler;

[0016] The methanol boiler on the burner is connected to an automatic control device that sends start / stop signals.

[0017] It also includes a combustion management system, a boiler safety protection system, and a human-machine interface.

[0018] The methanol valve assembly unit includes a #1 methanol shut-off valve and a methanol return regulating valve connected to the outlet of the methanol delivery pump. The #1 methanol shut-off valve is sequentially connected to a methanol flow meter, a methanol regulating valve, and a #2 methanol shut-off valve, which is connected to the burner. The methanol return regulating valve is connected to the methanol tank. The outlet of the #1 methanol shut-off valve is also connected to a nitrogen purging valve. A manual methanol shut-off valve is also connected upstream of the #1 methanol shut-off valve.

[0019] The fuel valve assembly includes a fuel regulating valve and a return fuel regulating valve connected to the outlet of the fuel delivery pump; the fuel regulating valve is sequentially connected to an electric heater, a No. 1 fuel cut-off valve, a No. 2 fuel cut-off valve, and a fuel flow meter, and the fuel flow meter is connected to the burner; the return fuel regulating valve is connected to the fuel tank.

[0020] The automatic control device automatically tracks the boiler steam pressure and automatically performs functions such as furnace fan purging before ignition, motor start / stop control, ignition, load tracking, nitrogen purging after shutdown, secondary ignition after purging, furnace fan purging after shutdown, and automatic boiler water replenishment.

[0021] It automatically ignites methanol or oil fuel, automatically adjusts fuel (methanol or oil) consumption, automatically adjusts the operating frequency of the combustion fan, and automatically adjusts the opening of the combustion damper to achieve stable fuel combustion. It also monitors boiler flame, water level, steam pressure, flue gas temperature, combustion air pressure, fuel parameters, valve limits, and combustible gas concentration in real time to ensure safe boiler operation.

[0022] When the boiler is operating on methanol fuel, if the fuel supply system malfunctions and the boiler must be stopped, the automatic control device will cut off the methanol fuel supply and automatically switch to fuel oil operation after the furnace purging is completed.

[0023] A control device equipped with an electric actuator and a combustion-supporting fan are included, with the control device connected to a damper. The combustion-supporting air volume is adjusted by regulating the operating frequency of the combustion-supporting fan and the opening degree of the electric actuator. A pneumatic regulating valve equipped with a controller adjusts the methanol or fuel oil consumption by adjusting its opening degree. A pneumatic switching valve equipped with a solenoid valve supplies or cuts off methanol, fuel oil, or nitrogen by energizing / de-energizing the solenoid valve. A pneumatic regulating valve equipped with a controller adjusts the boiler feedwater volume by adjusting its opening degree, maintaining a constant boiler water level.

[0024] This invention also provides an automatic control method for a marine methanol boiler, employing the aforementioned automatic control system for a marine methanol boiler. The method includes:

[0025] When methanol is the primary fuel, the automatic control device determines whether to start the boiler based on the boiler start / stop signal fed back from the boiler steam pressure transmitter. When the determination condition is met, the system sends a signal to the combustion fan frequency converter to start the combustion fan, which gradually accelerates the combustion fan to the rated frequency. At the same time, the automatic control device sends a signal to the combustion damper actuator to drive the combustion damper to the fully open position, initiating the pre-ignition furnace blower purging.

[0026] During this period, the automatic control device sends a signal to open the main methanol supply valve and receives the valve opening feedback signal. After the main methanol supply valve opening feedback signal is detected, the methanol delivery pump is started within seconds, and the outlet pressure of the methanol delivery pump is monitored to ensure it is normal. After the furnace blower completes purging before ignition, the automatic control device sends signals to the combustion damper actuator, combustion blower frequency converter, and methanol regulating valve, driving the combustion damper, combustion blower, and methanol regulating valve to the set ignition position. Simultaneously, the burner rotor motor and ignition pump are started to establish the pre-ignition verification conditions.

[0027] After the pre-ignition verification conditions are met, the burner sequentially activates the igniter and ignition solenoid valve, and monitors the establishment of the ignition flame in real time. Once the ignition flame stabilizes, the combustion fan frequency converter sends a signal to open the No. 1 and No. 2 methanol shut-off valves of the methanol valve group unit, allowing methanol fuel to enter the burner and be ignited by the ignition flame, while the establishment of the methanol flame is monitored in real time.

[0028] Once the methanol flame stabilizes, the automatic control unit automatically switches to the stable operation phase. During this period, the automatic control unit automatically adjusts the methanol regulating valve to maintain a constant methanol supply pressure.

[0029] During stable operation, the automatic control unit automatically adjusts the air and fuel supply based on the steam pressure demand to achieve the optimal air-fuel ratio. When the automatic control unit receives a shutdown signal, it signals to close the No. 1 and No. 2 methanol shut-off valves and starts the furnace blower for purging. During this period, the automatic control unit will signal to restart the ignition pump, igniter, and ignition solenoid valve to initiate secondary ignition, while simultaneously opening the nitrogen purging valve, methanol regulating valve, and No. 2 methanol shut-off valve to ensure that any residual methanol in the pipeline is blown into the furnace by nitrogen and ignited.

[0030] When fuel oil is the primary fuel or when methanol is the primary fuel and a fuel system malfunction occurs, the automatic control unit will initiate the fuel ignition procedure. Suitable fuels include light diesel oil, marine low-sulfur fuel oil (MGO), and heavy fuel oil (HFO). The difference lies in that when using heavy fuel oil, the automatic control unit will adjust the output power of the electric heater according to the fuel oil temperature to ensure the fuel oil temperature is maintained within a controllable range.

[0031] The boiler safety protection system monitors the boiler equipment, methanol valve group, fuel oil valve group, and all motor operating current parameters in real time via digital or analog signals. When any parameter anomaly occurs, the boiler safety protection system automatically shuts off the fuel shut-off valve and issues an alarm signal displayed on the human-machine interface.

[0032] This invention enables safe, reliable, and stable operation of marine boiler systems that use methanol or fuel oil as fuel. Attached Figure Description

[0033] The present invention will be further described in detail below with reference to the accompanying drawings.

[0034] Figure 1 This is a system connection diagram of the present invention. Detailed Implementation

[0035] like Figure 1 As shown, an automatic control system for a marine methanol boiler includes an automatic control device 1.

[0036] Automatic control device 1 is connected to combustion fan frequency converter 21 and combustion fan 2; combustion fan 2 is controlled by combustion fan frequency converter 21; combustion fan 2 supplies air to combustion damper and atomizing damper;

[0037] Automatic control device 1 is connected to combustion damper actuator 3, and controls combustion damper of burner 5 through combustion damper actuator 3;

[0038] Automatic control device 1 is connected to atomizing damper actuator 4, and controls the atomizing damper of burner 5 through atomizing damper actuator 4;

[0039] Automatic control device 1 is connected to exhaust fan 11;

[0040] Automatic control device 1 is connected to ignition pump 13 on burner 5;

[0041] Automatic control device 1 is also connected to methanol main supply valve 10, methanol delivery pump 6, methanol shut-off valve 8, methanol regulating valve 7, methanol shut-off valve 24, which supply methanol to burner 5.

[0042] Automatic control device 1 is also connected to fuel delivery pump 14, fuel regulating valve 17, electric heater 15, No. 1 fuel shut-off valve 16, and No. 2 fuel shut-off valve 26 that supply fuel to burner 5.

[0043] Automatic control device 1 is also connected to a water supply pump 19 and a water supply regulating valve 20 that supply water to the methanol boiler;

[0044] The methanol boiler on burner 5 is connected to automatic control device 1, which sends start / stop signals.

[0045] It also includes a combustion management system, a boiler safety protection system, and a human-machine interface.

[0046] The methanol valve assembly includes a #1 methanol shut-off valve 8 and a methanol return regulating valve 9 connected to the outlet of the methanol delivery pump 6. The #1 methanol shut-off valve 8 is sequentially connected to a methanol flow meter 22, a methanol regulating valve 7, and a #2 methanol shut-off valve 24, which is connected to the burner 5. The methanol return regulating valve 9 is connected to the methanol tank. The outlet of the #1 methanol shut-off valve 8 is also connected to a nitrogen purging valve 12. A methanol manual shut-off valve 25 is also connected upstream of the #1 methanol shut-off valve 8.

[0047] like Figure 1 As shown, the fuel valve assembly includes a fuel regulating valve 17 and a return fuel regulating valve 18 connected to the outlet of the fuel delivery pump 14; the fuel regulating valve 17 is connected in sequence to the electric heater 15, the No. 1 fuel cut-off valve 16, the No. 2 fuel cut-off valve 26, and the fuel flow meter 23, and the fuel flow meter 23 is connected to the burner 5; the return fuel regulating valve 18 is connected to the fuel tank.

[0048] It also includes a combustion management system (BMS), a boiler safety protection system (FSS), and a human-machine interface (HMI).

[0049] When methanol is the primary fuel, the automatic control device 1 determines whether to start the boiler based on the boiler start / stop signal fed back by the boiler steam pressure transmitter. When the determination condition is met, the system sends a signal to start the combustion fan frequency converter 21, which gradually accelerates the combustion fan 2 to the rated frequency. At the same time, the automatic control device 1 sends a signal to the combustion damper actuator 3, driving the combustion damper to the fully open position, and initiating the pre-ignition furnace blower purging.

[0050] During this period, the automatic control device 1 sends a signal to open the main methanol supply valve 10 and receives the valve opening feedback signal. Five seconds after the main methanol supply valve 10 opening feedback signal is detected, the methanol delivery pump 6 is started, and the outlet pressure of the methanol delivery pump 6 is monitored to ensure it is normal. After the furnace blower completes purging before ignition, the automatic control device 1 sends signals to the combustion damper actuator 3, the combustion blower frequency converter 21, and the methanol regulating valve 7, driving the combustion damper, blower, and methanol regulating valve 7 to the set ignition position. Simultaneously, the burner 5 rotor motor and ignition pump 13 are started to establish the pre-ignition verification conditions.

[0051] After the pre-ignition verification conditions are met, burner 5 sequentially activates the igniter and ignition solenoid valve, and monitors the establishment of the ignition flame in real time. Once the ignition flame stabilizes, the combustion fan frequency converter 21 sends a signal to open methanol shut-off valve 8 (No. 1) and methanol shut-off valve 24 (No. 2) of the methanol valve group unit, allowing methanol fuel to enter burner 5 and be ignited by the ignition flame, while monitoring the establishment of the methanol flame in real time.

[0052] Once the methanol flame stabilizes, the automatic control device 1 automatically enters the stable operation phase. During this period, the automatic control device 1 automatically adjusts back to the methanol regulating valve 9 to maintain a constant methanol supply pressure.

[0053] During stable operation, the automatic control device 1 automatically adjusts the air and fuel supply according to the steam pressure demand to achieve the optimal air-fuel ratio. When the automatic control device 1 receives a shutdown signal, it sends a signal to close the methanol shut-off valve and starts the furnace blower for purging. During this period, the automatic control device 1 will send a signal to restart the ignition pump 13, igniter, and ignition solenoid valve to initiate secondary ignition, while simultaneously opening the nitrogen purging valve 12, methanol regulating valve 7, and the second methanol shut-off valve 8 to ensure that any residual methanol in the pipeline is blown into the furnace by nitrogen and ignited.

[0054] When fuel oil is the primary fuel or when a fuel system malfunction occurs while using methanol as the primary fuel, the automatic control device 1 will initiate the fuel ignition procedure. Suitable fuels include light diesel oil, marine low-sulfur fuel oil (MGO), and heavy fuel oil (HFO). The difference lies in that when using heavy fuel oil, the automatic control device 1 will adjust the output power of the electric heater 15 according to the fuel oil temperature to ensure that the fuel oil temperature is maintained within a controllable range.

[0055] The boiler safety protection system (FSS) monitors parameters such as boiler equipment, methanol valve group, fuel oil valve group, and operating current of all motors in real time via digital or analog signals. When any parameter anomaly occurs, the FSS will automatically shut off the methanol or fuel oil shut-off valve and issue an alarm signal displayed on the human-machine interface (HMI).

Claims

1. An automatic control system for a marine methanol boiler, characterized in that, Includes automatic control device (1); Automatic control device (1) connects to combustion fan frequency converter (21) and combustion fan (2); combustion fan (2) is controlled by combustion fan frequency converter (21); combustion fan (2) supplies air to combustion damper and atomizing damper; The automatic control device (1) is connected to the combustion damper actuator (3) and controls the combustion damper of the burner (5) through the combustion damper actuator (3); The automatic control device (1) is connected to the atomizing damper actuator (4) and controls the atomizing damper of the burner (5) through the atomizing damper actuator (4); Automatic control device (1) is connected to exhaust fan (11); Automatic control device (1) is connected to ignition pump (13) on burner (5); The automatic control device (1) is also connected to the main methanol supply valve (10), methanol delivery pump (6), 1# methanol shut-off valve (8), methanol regulating valve (7), and 2# methanol shut-off valve (24) that supply methanol to the burner (5). The automatic control device (1) is also connected to a fuel delivery pump (14), a fuel regulating valve (17), an electric heater (15), a No. 1 fuel shut-off valve (16), and a No. 2 fuel shut-off valve (26) that supply fuel to the burner (5). The automatic control device (1) is also connected to the feed water pump (19) and the feed water regulating valve (20) that supply water to the methanol boiler. The methanol boiler on the burner (5) is connected to the automatic control device (1) and sends start / stop signals; It also includes a combustion management system, a boiler safety protection system, and a human-machine interface; It also includes a methanol valve assembly unit, which includes a #1 methanol shut-off valve (8) and a methanol return regulating valve (9) connected to the outlet of the methanol delivery pump (6); the #1 methanol shut-off valve (8) is connected in sequence to a methanol flow meter (22), a methanol regulating valve (7), and a #2 methanol shut-off valve (24), and the #2 methanol shut-off valve (24) is connected to the burner (5); the methanol return regulating valve (9) is connected to the methanol tank; the outlet of the #1 methanol shut-off valve (8) is also connected to a nitrogen purge valve (12); The methanol shut-off valve (8) is also connected upstream of the methanol manual shut-off valve (25); It also includes a fuel valve assembly, which includes a fuel regulating valve (17) and a return fuel regulating valve (18) connected to the outlet of the fuel delivery pump (14); the fuel regulating valve (17) is connected in sequence to the electric heater (15), the No. 1 fuel cut-off valve (16), the No. 2 fuel cut-off valve (26), and the fuel flow meter (23), and the fuel flow meter (23) is connected to the burner (5); the return fuel regulating valve (18) is connected to the fuel tank.

2. An automatic control method for a marine methanol boiler, characterized in that, The automatic control system for a marine methanol boiler according to claim 1, wherein the method comprises: When methanol is the main fuel, the automatic control device (1) determines whether to start the boiler based on the boiler start-up and shutdown signal fed back by the boiler steam pressure transmitter. When the determination condition is met, the system sends a signal to start the combustion fan frequency converter (21), and the combustion fan frequency converter (21) gradually accelerates the combustion fan (2) to the rated frequency. At the same time, the automatic control device (1) sends a signal to the combustion damper actuator (3) to drive the combustion damper to the fully open position and start the furnace blower purging before ignition. During this period, the automatic control device (1) sends a signal to open the methanol main supply valve (10) and receives the valve opening feedback signal; after the methanol main supply valve (10) opening feedback signal is detected for 5 seconds, the methanol delivery pump (6) is started, and the outlet pressure of the methanol delivery pump (6) is monitored to see if it is normal; after the furnace blower is purged before ignition, the automatic control device (1) sends a signal to the combustion damper actuator (3), the combustion blower frequency converter (21), and the methanol regulating valve (7) to drive the combustion damper, combustion blower (2), and methanol regulating valve (7) to run to the set ignition position; at the same time, the burner (5) rotor motor and ignition pump (13) are started to establish the pre-ignition verification conditions; After the pre-ignition verification conditions are met, the burner (5) sequentially opens the igniter and the ignition solenoid valve, and monitors the establishment of the ignition flame in real time; when the ignition flame is stable, the combustion fan frequency converter (21) sends a signal to open the 1# methanol shut-off valve (8) and 2# methanol shut-off valve (24) of the methanol valve group unit, so that the methanol fuel enters the burner (5) and is ignited by the ignition flame, and monitors the establishment of the methanol flame in real time; Once the methanol flame stabilizes, the automatic control device (1) automatically enters the stable operation phase; during this period, the automatic control device (1) automatically adjusts back to the methanol regulating valve (9) to keep the methanol supply pressure constant. During the stable operation phase, the automatic control device (1) automatically adjusts the air and fuel supply according to the steam pressure demand value to achieve the optimal air-fuel ratio. When the automatic control device (1) receives the shutdown signal, it sends a signal to close the 1# methanol shut-off valve (8) and the 2# methanol shut-off valve (24) and starts the furnace blower for purging. During this period, the automatic control device (1) will send a signal to start the ignition pump (13), igniter, and ignition solenoid valve again to start secondary ignition. At the same time, it opens the nitrogen purging valve (12), methanol regulating valve (7), and 2# methanol shut-off valve (24) to ensure that the residual methanol in the pipeline is blown into the furnace by nitrogen and ignited. When fuel oil is used as the main fuel or when methanol is used as the main fuel and the fuel system fails, the automatic control device (1) will start the fuel ignition procedure; the fuel oil is suitable for light diesel oil, marine low sulfur oil, and heavy oil; the difference is that when heavy oil is used, the automatic control device (1) will adjust the output power of the electric heater (15) according to the fuel oil temperature to ensure that the fuel oil temperature is maintained within the controllable range.

3. The automatic control method for a marine methanol boiler according to claim 2, characterized in that, The boiler safety protection system monitors the boiler equipment, methanol valve group, fuel oil valve group, and all motor operating current parameters in real time through switch signals or analog signals. When the parameters are abnormal, the boiler safety protection system will automatically shut off the fuel shut-off valve and issue an alarm signal displayed on the human-machine interface.

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