Combustion control system

Abstract

The utility model provides a combustion control system which mainly comprises a working PLC (programmable logic controller), a redundant PLC, a remote signal input expansion unit and a remote signal output expansion unit. A BOG flow controller, a combustion chamber pressure controller, a smoke exhaust temperature controller and a minimum selector are arranged in the controller system. Process variables mainly comprise BOG flow, combustion chamber pressure and exhaust gas temperature. A control object is a pneumatic actuator, and an actuator adjusting object is a flow adjusting device. Lightweight design of the combustion control system is achieved through remote IO design and the Ethernet technology, and meanwhile the intelligent level of the combustion control system is improved through logical operation. The application of the redundant PLC controller technology further improves the safety and reliability of the GCU equipment.

Description

Technical Field

[0001] The utility model relates to a combustion control system for controlling an evaporation gas combustion device of an LNG filling and transportation ship. Background Art

[0002] During the navigation of an LNG filling and transportation ship, natural gas (Boil Off Gas, hereinafter referred to as BOG) that is vaporized and evaporated due to heat exchange with the outside world is continuously generated. Generally, the BOG will be preferentially liquefied by a reliquefaction device and then transported back to the cabin for storage. When too much BOG is generated and the reliquefaction device cannot process it in time, the generation of excess BOG will significantly increase the pressure in the cargo hold, posing a great threat to the safe operation of the LNG ship. Due to the pollution and insecurity of BOG, the law no longer allows the direct discharge of evaporation gas into the atmosphere. In addition, before filling the cargo, the LNG cabin of the LNG filling ship needs to be purged with inert gas to ensure that there is no air in the cabin; at the same time, after unloading the cargo, the LNG cabin of the LNG filling ship needs to be purged with inert gas to ensure that there is no residual combustible gas in the cabin. In addition to inert gas, a large amount of natural gas also exists in the purge gas.

[0003] At present, the method for an LNG ship to handle BOG and purge gas containing combustible gas basically adopts a gas combustion device (Gas Combustion Unit, hereinafter referred to as GCU) to burn it and then discharge it into the atmosphere after dilution and cooling by a fan. The device uses a programmable logic controller PLC to achieve logic control and combustion load PID control. To ensure the reliability of the system, manufacturers usually adopt two sets of independent control systems. This system is relatively complex, occupies a large space in the cabin, and cannot achieve controller switching without stopping the machine, and the combustion load control accuracy is insufficient.

[0004] Therefore, it is necessary to design a hardware / software redundant control system with a compact structure, high control accuracy, and capable of achieving switching without stopping the machine to improve the safety of ship operation, the stability of the GCU system, and the combustion load accuracy of the GCU. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a safe, reliable, and stable GCU combustion control system, which solves the problems of lightweight and intelligent of the traditional control system.

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

[0007] A combustion control system mainly consists of a working PLC controller, a redundant PLC controller, a remote signal input expansion unit, and a remote signal output expansion unit. Inside the controller system, there are a BOG flow controller, a combustion chamber pressure controller, a smoke exhaust temperature controller, and a minimum selector. The process variables mainly consist of BOG flow, combustion chamber pressure, and smoke exhaust temperature. The control object is a pneumatic actuator, and the actuator regulates a flow regulating device.

[0008] The process variables of BOG flow, combustion chamber pressure, and smoke exhaust temperature are connected to the remote signal input expansion unit. The remote signal input expansion unit is connected to the working PLC controller through Ethernet. The working PLC controller and the redundant PLC controller are connected through Ethernet to form a redundant network. The working PLC controller sets three independent PID controllers for BOG flow controller, combustion chamber pressure controller, and smoke exhaust temperature controller. The output values of the three independent PID controllers are sent to the remote signal output expansion unit through the minimum selector as control signals. The remote signal output expansion unit connects the control signal to the pneumatic actuator, and the pneumatic actuator controls the opening degree of the flow regulating device to achieve BOG flow regulation. At the same time, the combustion of BOG with different flows will affect the combustion chamber pressure and the smoke exhaust temperature.

[0009] This utility model mainly consists of a PLC controller with software / hardware redundancy, a remote signal input expansion unit, and a remote signal output expansion unit. The PLC controller is in a redundant working state, with the working CPU and the standby CPU online simultaneously. When the working CPU fails, the redundant CPU can immediately switch to the working CPU to achieve seamless switching. The CPU is connected to the remote signal input expansion unit and the remote signal output expansion unit through Ethernet. The controlled process variables mainly include: BOG flow, smoke exhaust temperature, and combustion chamber pressure. The control object is a flow regulating device equipped with a pneumatic actuator. The control system sets a BOG flow controller, a smoke exhaust temperature controller, and a combustion chamber pressure controller. The controller that can access the control object is determined by logical operation through the minimum selector, and only the output value of the controller with the minimum output value is assigned to the control object. Description of the Drawings

[0010] The following further details this utility model in conjunction with the drawings.

[0011] Figure 1 It is the system connection diagram of this utility model. Detailed Embodiment

[0012] Describe the specific technical solution of this utility model in conjunction with the drawings.

[0013] As Figure 1As shown in the figure, a combustion control system mainly includes a working PLC controller 1, a redundant PLC controller 2, a remote signal input expansion unit 3, and a remote signal output expansion unit 4. Inside the controller system, there are a BOG flow controller 5, a combustion chamber pressure controller 6, a smoke exhaust temperature controller 7, and a minimum selector 8. The process variables mainly consist of the BOG flow 9, the combustion chamber pressure 10, and the smoke exhaust temperature 11. The control object is a pneumatic actuator 12, and the actuator adjustment object is a flow regulating device 13.

[0014] The process variables, namely the BOG flow 9, the combustion chamber pressure 10, and the smoke exhaust temperature 11, are connected to the remote signal input expansion unit 3. The remote signal input expansion unit 3 is connected to the working PLC controller 1 through Ethernet. The working PLC controller 1 and the redundant PLC controller 2 are connected through Ethernet to form a redundant network. The working PLC controller 1 sets three independent PID controllers, namely the BOG flow controller 5, the combustion chamber pressure controller 6, and the smoke exhaust temperature controller 7. The output values of the three independent PID controllers are sent as control signals to the remote signal output expansion unit 4 through the minimum selector 8. The remote signal output expansion unit 4 connects the control signal to the pneumatic actuator 12, and the pneumatic actuator 12 controls the opening of the flow regulating device 13 to achieve BOG flow regulation. At the same time, the combustion of BOG with different flows will affect the combustion chamber pressure 10 and the smoke exhaust temperature 11.

[0015] The utility model adopts a remote IO design and Ethernet technology, greatly reducing the complexity of the control system and realizing the lightweight of the combustion control system. At the same time, the coordinated operation of the three controllers, namely the BOG flow controller 5, the combustion chamber pressure controller 6, and the smoke exhaust temperature controller 7, and the application of the minimum selector 8 greatly improve the intelligent level of the combustion control system. The application of the redundant PLC controller technology further improves the safety and reliability of the GCU equipment.

Claims

1. A combustion control system, characterized in that: It comprises a working PLC controller (1), a redundant PLC controller (2), a remote signal input expansion unit (3), and a remote signal output expansion unit (4); The controller system is provided with a BOG flow controller (5), a combustion chamber pressure controller (6), an exhaust gas temperature controller (7) and a minimum selector (8); The process variables consist of BOG flow rate (9), combustion chamber pressure (10), and exhaust gas temperature (11); The controlled object is a pneumatic actuator (12), and the actuator regulation object is a flow regulating device (13); The process variables BOG flow rate (9), combustion chamber pressure (10), and exhaust gas temperature (11) are connected to the remote signal input expansion unit (3), the remote signal input expansion unit (3) is connected to the working PLC controller (1) via Ethernet, and the working PLC controller (1) and the redundant PLC controller (2) are connected via Ethernet to form a redundant network; The working PLC controller (1) is provided with three independent PID controllers, namely a BOG flow controller (5), a combustion chamber pressure controller (6), and a smoke exhaust temperature controller (7); the output values ​​of the three independent PID controllers send control signals to a remote signal output expansion unit (4) through a minimum selector (8); the remote signal output expansion unit (4) connects the control signals to a pneumatic actuator (12), and the pneumatic actuator (12) controls the opening of a flow regulating device (13) to achieve BOG flow regulation.

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