燃烧控制系统(中英对照翻译).doc

燃烧控制系统Combustion Control System 1燃烧控制系统的结构1. Combustion control system structure 燃烧控制系统为了满足机组负荷变化的需求和保证锅炉安全经济运行，按照协调控制的原则，燃料、送风和引风等子控制系统应根据燃料主控信号(来自燃料主控制系统)进行协调控制。其总体结构如图42所示。The combustion control system is intended to meet the changing needs of unit load and ensure safe and economic operation of the boiler. In accordance with the principle of coordinated control, sub-control systems for fuel, air supply and induced air should be subject to coordination and control according to the fuel master signal (from the fuel master control system). The overall structure is as shown in Figure 4-2. 机组协调控制系统燃料主控系统送风控制系统引风控制系统制系统携带风控制系统磨煤机煤位控制系统、一次风压控制系统等燃煤负荷指令RM送风量指令Vg燃料量送风量引风量图43燃烧控制系统的总体示意图Figure 4-3 Overall Schematic Map of Combustion Control System机炉主控制器将送出锅炉主控信号(燃烧率信号)，再分别下达到燃料、送风、引风子系统中去。对于直吹式制粉方式，通过调节给煤机转速和一次风流量来改变锅炉的燃料量，通过调节送风量和引风量来保证锅安全和经济燃烧。The boiler master controller will issue a boiler master control signal (combustion rate signal) and send it to the fuel, air supply and induced air sub-systems. In view of the direct-fired pulverizing method, the boiler fuel flow is changed by adjusting the coal feeder speed and the primary air flow, while the boiler safety and economic combustion is ensured by adjusting the air output and air input. Unit CCSFuel MCSAir Supply Control System Induced Draft Control System制系统Carrying Air Control System, Coal Mill Coal-position Control System, Primary Air Pressure Control System, etc.Fire Coal Load Demand RMAir Flow DemandFuel FlowAir FlowInduced Draft Flow由图43可见，当机组负荷变化需要改变燃料量时，由负荷控制系统中的燃料主控系统根据锅炉负荷指令产生燃煤负荷指令和风量指令，其中燃煤负荷指令送往燃料控制系统(包括磨煤机料位/给煤机转速控制、燃油控制、一次风压力控制、携带风控制和旁路风控制系统等)、送风控制系统(包括送风机压力控制、燃烧风控制系统等)和引风控制系统，使燃料、送风、引风等共同适应负荷变化，保证锅炉安全经济运行。Figure 4-3 shows that, when the fuel flow needs to be changed in case of changes in the unit load, the fuel master control system in the load control system will generate a fire coal load demand and an air flow demand according to the boiler load demand. The fire coal load demand is sent to the fuel control system (including coal mill level / coal feeder speed control, fuel control, primary air pressure control, carrying air control and bypass air control system, etc.), the supply air control system (including air supply fan pressure control, combustion air control system, etc.) and the induced air control system. This allows the fuel, supply air, induced air, etc. to commonly adapt to changes in load, thereby ensuring safe and economic operation of the boiler. 可以看出燃烧控制系统是一个典型的多变量、多级耦合的控制系统。整个燃烧控制系统中的风、煤各子系统都串接在协调控制系统的下级，协调控制系统输出的锅炉负荷指令统一指挥风、煤各子系统的协调动作。It can be seen that the combustion control system is a typical multi-variable control system of multi-stage coupling. The air and coal subsystems in the entire combustion control system are cascaded in the lower level of the coordinated control system. The boiler load demand input by the coordinated control system gives unified command to the coordinated action of air and coal subsystems. 燃料主控系统是串接在协调控制系统下的一个“比值一串级”控制系统，燃料主控制系统的输出指令是携带风控制系统的给定值，携带风调节器根据该指令与携带风实际风量的偏差信号控制磨煤机入口管路的风门开度，以调整一次风量，从而适应锅炉负荷所需的煤粉量。为了保证稳定地供应所需煤粉量，就必须稳定一次风压，为此通过一次风控制系统控制两台一次风机的入口导向挡板开度，以保证一次风压稳定。The fuel master control system is a “ratio-cascade” control system cascaded to the coordinated control system. The output demand of the fuel master control system is a given value of the carrying air control system. The carrying air regulator controls the throttle opening of the coal mill inlet line according to the deviation signal between this demand the actual carrying air flow, so as to adjust the primary air flow and accommodate the amount of pulverized coal required by the boiler load. In order to ensure stable supply of pulverized coal required, the primary air pressure must be stable. Therefore, the primary air control system controls the opening of the inlet guide baffle of two primary air fans so as to ensure the stability of the primary air pressure. 锅炉送风量控制系统是串接在燃料主控制系统下的一个具有氧量校正的比值控制系统。保持进入锅炉炉膛的实际总风量与锅炉燃料量相适应，从而间接保证风煤比最佳。在具体实施过程中，该系统又通过送风压力控制系统、燃烧风(包括辅助风、燃尽风、夹心风等)控制系统以及气一汽温度控制系统等实现。The boiler air output control system is a ratio control system which is cascaded to the fuel master control system and is capable of oxygen correction. The actual total flow entering the boiler furnace should be maintained appropriate for the boiler fuel flow, so as to indirectly ensure the optical air-coal ratio. In the specific implementation process, the system is achieved through the supply air pressure control system, the combustion air (including auxiliary air, over fire air, sandwich air, etc.) control system, and the gas-steam temperature control system. 炉膛负压是通过调整两台引风机的静叶片来改变烟气量，以维持炉膛压力为设定值。为了使引风控制不滞后于送风控制，在引风控制系统中采用了具有风量指令微分信号前馈作用的单回路定值调节系统。The furnace negative pressure changes the volume of flue gas by adjusting the static blade of the two induced draft fans, so as to maintain the set value of the furnace pressure. To ensure that induced air control does not fall behind supply air control, the induced air control system employs a single-loop fixed value regulating system capable of differential single feedforward action of air flow demand. 综上所述，燃烧控制系统必须保证燃料是与空气量的配合，又必须保证引风和送风的配合。然而像燃料量的控制又依次关联到一次风量、一次风压和原煤给煤量(即磨煤机煤位给煤机转速)等的控制，各控制系统之间互相关联，不能脱节，否则将难以保证整个燃烧控制系统任务的完成。In summary, the combustion control system must ensure coordination between fuel and air amount and between induced air and supply air. However, the control of fuel flow is related to the control of primary air flow, primary air pressure and feed amount of raw coal (i.e. coal mill level / coal feeder speed). All control systems are interrelated and inseparable, otherwise it will be difficult to guarantee the completion of tasks of the entire combustion control system. 2信号的修正和限制2. Signal correction and restrictions 1) 水煤比修正1) Correction of coal-water ratio 水煤比直接反应出锅炉热量和工质的比例，因此，可以利用水煤比信号对蒸汽温度进行校正。水煤比通过计算分离器出口过热度与设定值的偏差，通过锅炉主控改变燃料主控的输出值，从而实现了对锅炉热量的偏置修正。The water-coal ratio directly reflects the proportion of boiler heat and working medium. Therefore, the water-coal ratio signal can be made use of to correct the steam temperature. By calculating the deviation between the degree of superheat at separator outlet and the set value and by changing the output value of the fuel master through the boiler master, the water-coal ratio corrects the deviation of boiler heat. 2) 总风量和燃料量的限制(风煤交叉限制)作用2) Restriction of total air flow and fuel flow (air-coal crossing restriction)整个燃烧控制系统中，来自协调控制系统的负荷指令并不直接作为燃料及送风两大控制系统的指令信号。而是由下列四个信号通过高选后得到：经氧量修正后的锅炉指令、测量到的总燃料量、热量和最小风量设定值(30)。这个回路随时保证安全的风煤比。当指令增大时，由于主燃料量指令受实际测量到的经补偿后的总风量的闭锁，实际燃料量和热量不会马上增大，风量指令就取决于锅炉指令。在实际风量上升以后，主燃料才开始增加，这样就达到了先增风后增煤的目的。反之风量指令受到了实际燃料量和热量的闭锁。在减负荷时，只有燃料量和热量减小时，风量控制系统才开始动作。当负荷低于30额定负荷时，为了保证锅炉的安全燃烧，风量保持在30。保证燃烧过程中始终是“总风量大于总燃料量”，以达到良好的燃烧经济性。In the entire combustion control system, the load demand from the coordinated control system is not directly used as a demand signal of the fuel and air supply control systems. Instead, it is obtained after high selection of the following four signals: boiler demand after oxygen correction, measured total fuel flow, heat and maximum set value of air flow (30%). This loop can ensure a safe air-coal ratio at any time. When the demand increases, as the demand of total fuel flow is blocked by the compensated total air flow which is actually measured, the actual fuel flow and heat will not immediately increase, then the air flow demand will be depend on the boiler demand. The main fuel begins to increase only after the actual air flow rises, thereby achieving the purpose of first increasing air and then increasing coal. Conversely, the air flow demand is l by the actual fuel flow and heat. To reduce the load, the air flow control system will begin to operate only when the fuel flow and heat is reduced. If the load is below 30% of the rated load, the air flow should be maintained at 30% to ensure safe combustion of the boiler. Ensure that the “total air flow is greater than the total fuel flow” throughout the combustion process, so as to achieve higher combustion economy. 3) 给煤量的测量与校正3) Measurement and correction of coal feed amountThe feed amount signal of the coal feeder is given by the weighing device of the electronic gravity-type belt feeder. The weighing device can measure the coal weight and belt speed at unit belt length and output the product of the two as the coal amount signal. The total fuel flow is the sum of the feed amount of all coal feeders. The coal quality and moisture may be readily changed, in other words, the calorific value of fire coal is not constant. Therefore, the fuel flow may not precisely correspond to the boiler heat. It is difficult to ensure the quality of control if only the measurement signal of fuel flow participates in feedback control. To solve this problem, the calorific value of the fuel flow signal should be corrected. 目前，煤的发热量尚不能实现瞬时测量，所以在燃料量控制系统中常采用热量信号(锅炉的实际吸热量)作为燃煤信号发热量校正的基本依据。Currently, instantaneous measurement of the coal calorific value is impossible to realize. Therefore, the heat signal (actual heat absorption of the boiler) is often used in the fuel flow control system as the fundamental basis to correct the calorific value of fire coal signal. 4) 控制回路的增益修正4) Gain correction of control loop 燃料主控制器输出的总燃煤指令对所有给煤机转速并行控制，当投入自动的给煤机台数不同时，整个控制回路的控制增益也是不同的。为了保证各工况下控制系统的稳定，必须按投入自动的实际给煤机台数，进行系统的增益修正。考虑在正常情况下为6台磨运行l台备用，所以取6台给煤机自动运行时系统增益修正系数为1。当n台给煤机投入自动运行时，系统增益修正系数为：Kn=6/n。The total coal demand output by the fuel master controller gives parallel control to the speed of all coal feeders. If the number of automatic feeders that are put into operation is different, the control gain of the entire control loop will be different. To ensure the stability of the control system in various operating conditions, the system gain correction must be as per the actual number of automatic feeders that have been put into service. In normal circumstances, 6 mills will be in service and 1 will stand by. Therefore, the system gain correction factor will be 1 when the 6 feeders are in automatic operation. Provided n sets of feeders are put into automatic operation, the system gain correction factor will be: Kn=6/n5) 氧量校正。5) Oxygen correction氧量校正调节器和风量调节器构成了串级调节系统，它能校正15的风量，由于煤量控制系统和风量控制系统在升降负荷过程中能同步协调动作，氧量校正只起着细调的作用。氧量设定值由蒸汽流量经函数发生器产生或由运行操作员设定，经过对函数发生器的输出与手动给定值比较，选用二者的大值作为系统的氧量设定值。对定压运行和滑压运行两种方式可采用不同的氧量设定值，由机组协调控制