Plasma ignition and stable combustion control system

Abstract

A plasma ignition and stable combustion control system comprises a main control unit, a plasma direct-current power supply control cabinet, a plasma generator, an FSSS system, a DCS and a sensing unit. The main control unit is in communication connection with the FSSS system and the DCS; the signal output end of the plasma direct-current power supply control cabinet is connected with the FSSS system; the sensing unit comprises a plasma generator state sensor, a plasma generator wall temperature sensor, a cooling water mother pipe pressure sensor and an air heater air outlet temperature sensor; the plasma generator state sensor and the plasma generator wall temperature sensor are connected with the input end of the main control unit; the cooling water mother pipe pressure sensor and the air heater air outlet temperature sensor are connected with the input end of the DCS. According to the utility model, the optimization of the ignition and stable combustion process of the boiler in the thermal power plant is realized, the rapidness and stability of ignition are ensured, and the energy utilization efficiency and the environmental protection level are improved at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of ignition and combustion control of power plant boilers, in particular to a plasma ignition and stable combustion control system. Background Art

[0002] With the increasing demand for energy and the increasing pressure on environmental protection, thermal power generation, as one of the main ways of electricity production, is particularly important for its efficient, clean and stable operation. Traditional thermal power generating units usually rely on oil fuel for ignition and stable combustion during startup and low-load operation, which not only increases fuel costs, but also causes certain pollution to the environment.

[0003] The problems with traditional ignition methods mainly include: strong dependence on fuel oil, high fuel consumption during ignition and high cost; poor combustion stability, which can easily cause combustion system oscillations and affect the safe and stable operation of the boiler; high NOx emissions during combustion, which is not conducive to environmental protection; and incomplete combustion of pulverized coal under low load, the resulting slag will damage the equipment and increase maintenance costs.

[0004] In order to solve the above problems, plasma ignition technology was proposed and applied to power plants. Plasma ignition technology uses high-temperature plasma to ignite coal powder to start the boiler. It can achieve rapid ignition without the need for fuel oil, which helps reduce the generation of NOx. However, the existing plasma ignition system has deficiencies in control logic, resulting in the need to improve ignition stability and efficiency, and is unable to adapt to complex and changing combustion environments and improve the system's adaptability. For example, the control of the plasma ignition system must ensure both the success rate of ignition and stable combustion under different operating conditions, which places higher requirements on the control system. Utility Model Content

[0005] The purpose of the utility model is to overcome the above-mentioned deficiencies of the prior art and to provide a plasma ignition and stable combustion control system which has high stability, is environmentally friendly and saves energy consumption.

[0006] The technical solution of the utility model is: a plasma ignition and stable combustion control system, comprising a main control unit, a plasma DC power supply control cabinet, a plasma generator, a FSSS system, a DCS and a sensor unit; the main control unit is respectively connected to the FSSS system and the DCS for communication; the signal output end of the plasma DC power supply control cabinet is connected to the FSSS system; the sensor unit comprises a plasma generator state sensor, a plasma generator wall temperature sensor, a cooling water pipe pressure sensor, and a heater outlet temperature sensor; the plasma generator state sensor and the plasma generator wall temperature sensor are connected to the input end of the main control unit; the cooling water pipe pressure sensor and the heater outlet temperature sensor are connected to the input end of the DCS.

[0007] Furthermore, the output end of the FSSS system is connected to a coal mill.

[0008] Furthermore, the plasma DC power supply control cabinet also provides the required power to the plasma generator and manages power distribution.

[0009] Furthermore, the output end of the DCS is connected to the actuator.

[0010] Furthermore, the actuator includes a cooling water pump, an auxiliary steam electric door and a heater.

[0011] Furthermore, the sensing unit also includes a flame detection sensor, and the flame detection sensor is connected to the FSSS system.

[0012] Furthermore, the FSSS system communicates data with the main control unit through a communication interface, and is used to send boiler operating parameters to the main control unit; the input end of the FSSS system is connected to the plasma DC power supply control cabinet, and is used to receive plasma generator status information sent from the plasma DC power supply control cabinet to determine whether the coal mill start-up conditions are met; the output end of the FSSS system is connected to the coal mill, and is used to control the start and stop of the coal mill and the switching of operation modes.

[0013] Furthermore, the main control unit includes a microprocessor and its supporting interface circuit, power supply circuit, signal conditioning circuit, isolation protection circuit and watchdog circuit; and is connected to other systems through digital input / output, analog input and communication interface.

[0014] Furthermore, the DCS includes a human-machine interface and an alarm.

[0015] Beneficial effects of the utility model:

[0016] 1. By electrically connecting the main control unit, plasma DC power supply control cabinet, plasma generator, FSSS system and DCS, and coordinating with various sensors, the preheating and warm grinding operation of the heater during cold ignition is increased to ensure the stability and success rate of the ignition process. The main control unit can dynamically adjust the ignition energy and combustion air supply of the plasma generator according to the status information feedback of the plasma generator and FSSS system to optimize the ignition and stable combustion process and reduce the fluctuation in the combustion process, so that the plasma ignition system can more accurately control the working state of the coal mill to adapt to different ignition and combustion support requirements;

[0017] 2. Traditional oil-based ignition is prone to produce pollutants due to incomplete combustion, while the improved plasma ignition system can achieve cleaner combustion and reduce the impact on the environment;

[0018] 3. Due to the high efficiency of plasma ignition technology, the use of the control system provided by this application can reduce the auxiliary energy required for combustion, thereby reducing operating costs and saving energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a control system connection block diagram of an embodiment of the utility model. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] like Figure 1 Shown: A plasma ignition and stable combustion control system, including a main control unit, a plasma DC power supply control cabinet, a plasma generator, a FSSS system (boiler combustion management system), a DCS (distributed control system) and a sensor unit, to achieve optimized control of the plasma ignition and stable combustion system.

[0022] The specific connection relationship is:

[0023] The sensing unit includes a plasma generator status sensor, a plasma generator wall temperature sensor, a cooling water pipe pressure sensor, a heater outlet temperature sensor and a flame detection sensor. Among them, the ion generator status sensor specifically includes a voltage sensor, a current sensor and an airflow detection sensor, which are used to collect the operating status of the plasma generator, such as current, voltage, airflow, etc.; the plasma generator status sensor is connected to the input end of the main control unit, and is used to send the collected status signal to the main control unit. The plasma generator wall temperature sensor is connected to the input end of the main control unit, and is used to detect the wall temperature of the plasma generator and send the inner wall temperature signal to the main control unit. The cooling water pipe pressure sensor is connected to the input end of the DCS, and is used to detect the cooling water pipe pressure of the plasma cooling water pump, and send the pressure signal to the DCS as one of the conditions for starting the plasma system, and is displayed on the human-machine interface of the DCS. The heater outlet temperature sensor is connected to the DCS to determine whether the heater outlet temperature reaches the condition for starting the A-layer coal mill, and sends the temperature signal to the DCS as one of the conditions for starting the A-layer coal mill, and displays it on the human-machine interface of the DCS. The flame detection sensor is a camera, which is connected to the FSSS system for communication and is used to send the detected flame image to the FSSS system to determine whether the ignition is successful.

[0024] The output end of the plasma DC power supply control cabinet is connected to the FSSS system, and is used to send signals such as "plasma system normal operation", "plasma system failure" and "plasma system allowed to start" to the FSSS system; and the plasma DC power supply control cabinet also provides the required power to the plasma generator and manages power distribution. In this embodiment, the plasma DC power supply control cabinet is a mature technology in the field of plasma ignition, and its internal structure will not be described in detail here.

[0025] The FSSS system communicates data with the main control unit through a communication interface (such as RS485) to send boiler operating parameters (such as temperature, pressure, and flow) to the main control unit; the input end of the FSSS system is also connected to the plasma DC power supply control cabinet to receive "plasma system normal operation", "plasma system failure" and "plasma system start-up allowed" signals sent from the plasma DC power supply control cabinet to determine whether the coal mill start-up conditions are met and execute corresponding interlocking protection logic; the output end of the FSSS system is connected to the coal mill to control the start and stop of the coal mill and the switching of operating modes (such as ignition mode, combustion-supporting mode, etc.); the input end of the FSSS system is connected to the flame detection sensor to determine whether the coal mill ignition is successful through image flame detection and monitor the flame status in real time.

[0026] The DCS communicates data with the main control unit through a communication interface (such as Ethernet), is used to receive various status signals and parameters sent by the main control unit, and displays the plasma generator wall temperature and plasma generator status information through a human-machine interface, and provides alarm and operation functions. It is also used to send setting parameters and control instructions to the main control unit, such as plasma generator start / stop operation, current setting, etc., which are all operated in the DCS interface; the output end of the DCS is also connected to an actuator, which includes a cooling water pump, an auxiliary steam electric door and a heater, which is used to remotely control the start and stop of the cooling water pump, and monitor the cooling water main pipe pressure as one of the coal mill start-up conditions, and also measures the heater outlet temperature to determine whether the heater meets the preheating requirements as one of the coal mill start-up conditions. The DCS can also communicate data with the FSSS system through a communication interface, and is used to receive instructions from the FSSS system to control the opening of the cooling water pump, the auxiliary steam electric door, and the heater. Among them, the auxiliary steam electric door is an electric control valve used in the ignition process of a coal-fired boiler. It is mainly used to control the supply of auxiliary steam (auxiliary steam for short). Auxiliary steam is steam other than main steam, usually coming from the medium-pressure or low-pressure steam system of the boiler, with relatively low pressure and temperature.

[0027] The input end of the plasma generator is connected to the output end of the main control unit for receiving a start / stop control signal.

[0028] The main control unit includes a microprocessor and its supporting interface circuit, power supply circuit, signal conditioning circuit, isolation protection circuit and watchdog circuit, etc. It is connected to other systems through digital input / output (DI / DO), analog input (AI), communication interface (such as RS485, Ethernet), etc. The main control unit dynamically adjusts the ignition energy and combustion air supply of the plasma generator by receiving feedback signals from boiler parameters such as temperature, pressure, flow, etc., so as to optimize the ignition and stable combustion process.

[0029] The workflow of this embodiment is:

[0030] After the boiler is purged, the FSSS system selects whether to enter the plasma ignition mode. If it enters the ignition mode, it sends a command to the DCS, and the DCS remotely controls the cooling water pump to start. The cooling water pipe pressure sensor detects the pressure of the cooling water pipe and sends it to the DCS. If it is judged that the cooling water pipe pressure meets the conditions, the ignition starts, the DCS controls the auxiliary steam electric door to open, and the heater is put into operation. The heater outlet temperature sensor detects the heater outlet temperature and sends the temperature information to the DCS. The DCS determines whether the heater outlet temperature is ≥160℃. If so, it is one of the necessary conditions for starting the coal mill. After selecting the "ignition mode" to run, the heater needs to be put into operation in advance to participate in the warm mill. The second necessary condition for starting the coal mill includes: if it is judged that the cooling water mother pipe pressure meets the conditions, the ignition starts, the plasma generator is started by the main control unit, and the plasma generator sends the status feedback signal (such as current, voltage, airflow) to the main control unit. If the main control unit judges that the plasma generator is operating normally, it also serves as the second necessary condition for starting the coal mill; the third necessary condition for starting the coal mill includes: the plasma DC power supply control cabinet sends to the FSSS system: 1) 4 "plasma system normal operation" signals; 2) 4 "plasma system fault" signals; 3) 4 "plasma system allowed to start" signals; when the coal mill is running in the "ignition mode", the plasma DC power supply control cabinet sends 4 "plasma system normal operation" signals to the FSSS system as one of the coal mill start-up conditions, and the coal mill is started when other start-up conditions are met at the same time. Similarly, the 4 "plasma system fault" signals participate in the coal mill control protection. After the coal mill is turned on, the flame detection sensor detects the coal fire status and sends it to the FSSS system. The FSSS system determines whether there is fire through image flame detection. If there is fire, the ignition is successful and the flame status is detected in real time.

[0031] When the coal mill is running in the "ignition mode", if any "plasma system fault" or any "coal fire detection signal" is lost during the plasma ignition process, the delay is 20s (plasma arc re-pulling time or coal fire detection re-detection time). If the above signals still exist, the FSSS system executes the corresponding interlocking protection logic, such as tripping the primary air fast closing door of the corresponding coal mill outlet; when the plasma fault is restored and the "plasma system normal operation" signal comes, the "plasma system fault" signal disappears, and the primary air fast closing door of the corresponding coal mill outlet is reopened.

[0032] When the boiler is running with more than 3 mills and the load is greater than 45%, the system switches to combustion-supporting mode.

[0033] The wall temperature of the plasma generator is detected by the plasma generator wall temperature sensor and displayed on the DCS interface. When the wall temperature is greater than 400°C, the first over-temperature alarm threshold is set, and when it is greater than 500°C, the second over-temperature alarm threshold is set. Once the alarm threshold is exceeded, the DCS alarm prompts to remind the operator to handle it.

[0034] The core technical principle of this embodiment is to use the characteristics of high-temperature plasma to achieve rapid ignition and stable combustion of coal powder. Plasma is a state of matter composed of partially or fully ionized gas. It generates high temperature under the action of electromagnetic field, which can quickly ignite coal powder to form a combustion core, thereby starting the boiler. Through the feedback control of the main control unit, plasma generator and FSSS system, the ignition process can be automatically adjusted according to real-time data, which not only ensures the success rate of ignition, but also ensures the stability of combustion. In addition, the improved plasma generator design improves the temperature and stability of plasma, thereby improving combustion efficiency and reducing fuel consumption; it can also dynamically adjust the energy output of the plasma generator according to the actual combustion situation, which not only improves the ignition and combustion efficiency of coal powder, but also significantly reduces the fuel oil consumption required for traditional ignition methods, achieving both economic and environmental benefits.

[0035] In summary, this embodiment optimizes the ignition and stable combustion process of the boiler in a thermal power plant, ensures rapid and stable ignition, and improves energy efficiency and environmental protection.

Claims

1. A plasma ignition and stable combustion control system, characterized in that: It includes a main control unit, a plasma DC power supply control cabinet, a plasma generator, a FSSS system, a DCS and a sensor unit; the main control unit is communicatively connected to the FSSS system and the DCS; the signal output end of the plasma DC power supply control cabinet is connected to the FSSS system; the sensor unit includes a plasma generator state sensor, a plasma generator wall temperature sensor, a cooling water jelly pipe pressure sensor, and a heater outlet temperature sensor; the plasma generator state sensor and the plasma generator wall temperature sensor are connected to the input end of the main control unit; the cooling water jelly pipe pressure sensor and the heater outlet temperature sensor are connected to the input end of the DCS.

2. The plasma ignition and stable combustion control system according to claim 1, characterized in that: The output end of the FSSS system is connected to a coal mill.

3. The plasma ignition and stable combustion control system according to claim 1, characterized in that: The plasma DC power supply control cabinet also provides the required power to the plasma generator and manages power distribution.

4. The plasma ignition and stable combustion control system according to claim 1, characterized in that: The output end of the DCS is connected to the actuator.

5. The plasma ignition and stable combustion control system according to claim 4, characterized in that: The actuator includes a cooling water pump, an auxiliary steam electric door and a heater.

6. The plasma ignition and stable combustion control system according to claim 1, characterized in that: The sensing unit further comprises a flame detection sensor, and the flame detection sensor is connected to the FSSS system.

7. The plasma ignition and stable combustion control system according to claim 6, characterized in that: The FSSS system communicates data with the main control unit through a communication interface, and is used to send boiler operating parameters to the main control unit; the input end of the FSSS system is connected to the plasma DC power supply control cabinet, and is used to receive the plasma generator status information sent from the plasma DC power supply control cabinet to determine whether the coal mill start-up conditions are met; the output end of the FSSS system is connected to the coal mill, and is used to control the start and stop of the coal mill and the switching of the operation mode.

8. The plasma ignition and stable combustion control system according to claim 1, characterized in that: The DCS includes a human-machine interface and an alarm.

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