Characteristics and control principle of automatic pressure maintaining hydraulic control butterfly valve

自动保压式液控蝶阀的特性及控制原理
Characteristics and control principle of automatic pressure maintaining hydraulic control butterfly valve

    某公司一、二期循环泵出口采用KD741X-6V型自动保压式液控蝶阀。由于该阀液压控制部分经常出现故障，如果对液压控制原理不清楚，极易造成误操作，导致循环泵停运，严重时还会造成停机事故。该厂3号机就曾因液压控制系统手动阀误关闭，在循环泵事故停运后该蝶阀未能关闭，使凝汽器真空降低，造成机组停运。
Kd741x-6v automatic pressure maintaining hydraulic control butterfly valve is used at the outlet of circulating pump in phase I and phase II of a company. As the hydraulic control part of the valve often fails, if the hydraulic control principle is not clear, it is easy to cause misoperation, leading to the shutdown of the circulating pump, and even the shutdown accident. The No.3 unit of the plant was closed by mistake due to the manual valve of the hydraulic control system, and the butterfly valve failed to close after the accident shutdown of the circulating pump, which reduced the vacuum of the condenser and caused the unit shutdown.

(1)蝶阀的特性
(1) Characteristics of butterfly valve

    自动保压式液控蝶阀是根据启、停泵的水力过渡过程理论，采取分阶段按程序开、关阀。当循环水泵失电停运时，蝶阀自动按调定好的程序先快关截断大部分水流，起到止回阀的作用；然后慢关至全关，起到消除水锤危害、缓冲和截止的作用，具有水泵出口处闸阀和止回阀的功能。开阀时间可调，关阀时先快关后慢关，快、慢关时间和角度可调，可根据电厂的要求调节时间和角度。此外，配有电动和手动两套系统，操纵阀门的开启和关闭。该蝶阀还有电气自动控制的开关阀系统、泵阀联动系统、远程控制、自动补油行程开关、泵阀联动行程开关等。可单独或与水泵联动开启和关闭，实现自动控制。
The automatic pressure maintaining hydraulic control butterfly valve is based on the theory of the hydraulic transition process of starting and stopping the pump, and adopts the method of opening and closing the valve in stages according to the procedure. When the circulating water pump is shut down due to power loss, the butterfly valve will automatically close quickly according to the set procedure to cut off most of the water flow and act as a check valve; Then slowly close to full close, to eliminate the harm of water hammer, buffer and cut-off function, with the pump outlet gate valve and check valve function. The opening time of the valve can be adjusted. When the valve is closed, the time and angle of fast and slow closing can be adjusted. The time and angle can be adjusted according to the requirements of the power plant. In addition, it is equipped with two sets of electric and manual systems to control the opening and closing of the valve. The butterfly valve also has electric automatic control on-off valve system, pump valve linkage system, remote control, automatic oil filling travel switch, pump valve linkage travel switch, etc. It can be opened and closed by itself or linkage with water pump to realize automatic control.

    该蝶阀靠液压驱动，开阀时由液压泵电机提供动力，关阀时由升起的重锤提供动力。关阀时不需驱动电源，不会发生无驱动电源或者蝶阀意外故障使液压系统失压而导致蝶阀不能关闭的现象，可避免大量水体倒流、管网系统失压及损坏水泵事故的发生。液压系统中设有自动保压的蓄能器装置，使阀门全开后重锤和蝶板不摆动，无掉锤现象，阀门在最小流阻状态下运行，安全可靠。
The butterfly valve is driven by hydraulic pressure. When the valve is opened, the power is provided by the motor of the hydraulic pump. When the valve is closed, the power is provided by the lifting hammer. When the valve is closed, there is no need for the driving power supply, and the butterfly valve can not be closed due to the pressure loss of the hydraulic system due to the failure of the driving power supply or the unexpected failure of the butterfly valve, which can avoid the occurrence of a large number of water backflow, pressure loss of the pipe network system and damage to the pump. The hydraulic system is equipped with an accumulator device with automatic pressure maintaining, so that the heavy hammer and butterfly plate will not swing after the valve is fully opened, and there is no hammer drop phenomenon. The valve operates in the state of minimum flow resistance, which is safe and reliable.

(2)控制原理
(2) Control principle

KD741X-6V型蝶阀的控制原理如图H所示。
The control principle of kd741x-6v butterfly valve is shown in Figure H.

    机组在正常运行状态下，循环泵的启停靠该蝶阀的开启和关闭与之联锁来实现，这样可对循环泵起到保护作用，也可以防止由于循环泵事故停运造成循环水倒流、凝汽器真空降低、机组跳机事件的发生。
When the unit is in normal operation, the start and stop of the circulating pump and the opening and closing of the butterfly valve are interlocked, which can protect the circulating pump and prevent the backflow of circulating water, the reduction of condenser vacuum and the unit tripping caused by the accident shutdown of the circulating pump.

    ①开阀过程当循环泵需要启动运行时，首先启动蝶阀的液压泵电机，带动运转，液压油经滤网、液压泵、调速阀、及高压胶管进入液压缸，推动液压缸活塞移动。未通过调速阀的多余液压油经溢流阀流回油箱。液压缸活塞带动与之相连的连接头使重锤升起，并同时带动阀轴使蝶板开启。当开启到15°时，联锁循环泵启动，蝶阀继续开启至全开位置。随后蓄能器充油至额定值，撞动行程开关XK3（图中未示出），使液压泵电机停止，完成蝶阀的开启及循环泵的启动。
① When the circulating pump needs to be started during the valve opening process, the motor of the hydraulic pump of the butterfly valve is first started to drive the operation. The hydraulic oil enters the hydraulic cylinder through the filter screen, the hydraulic pump, the speed regulating valve and the high-pressure hose to push the piston of the hydraulic cylinder to move. The excess hydraulic oil that does not pass through the speed regulating valve flows back to the oil tank through the relief valve. The piston of the hydraulic cylinder drives the connecting head connected with it to raise the heavy hammer, and at the same time drives the valve shaft to open the butterfly plate. When the valve is opened to 15 degrees, the interlock circulating pump starts and the butterfly valve continues to open to the full open position. Then, the accumulator is filled with oil to the rated value, and the stroke switch xk3 (not shown in the figure) is knocked to stop the motor of the hydraulic pump to complete the opening of the butterfly valve and the start of the circulating pump.

    ②关阀过程当循环泵需要停运时，电磁阀带电，则电磁阀打开，在重锤的作用下，液压缸内的压力油经快、慢关角度调节阀，快关调节阀，慢关调节阀，高压胶管，常开的手动阀1和电磁阀流入油箱，利用重锤势能带动蝶板关闭，实现蝶阀的关阀。当关闭到15°时，联锁循环泵停运，蝶阀继续关闭至O°，完成蝶阀的关闭及循环泵的停运（蝶阀关闭位置为O°，全开位置为90°）。
② When the circulating pump needs to be shut down, the solenoid valve will be opened when it is charged. Under the action of the heavy hammer, the pressure oil in the hydraulic cylinder will flow into the oil tank through the fast and slow closing angle regulating valve, fast closing regulating valve, slow closing regulating valve, high-pressure hose, normally open manual valve 1 and solenoid valve, and the butterfly plate will be closed by using the potential energy of the heavy hammer to realize the valve closing of the butterfly valve. When the valve is closed to 15 degrees, the interlocking circulating pump will stop, and the butterfly valve will continue to close to o degrees to complete the closing of the butterfly valve and the shutdown of the circulating pump (the butterfly valve is closed at o degrees, and the full open position is 90 degrees).

    ③全开后自动保压为保证液压缸长期工作时压力不低于所需油压，使重锤不因油压力过低而下降，在液压系统油路中并联一弹簧式蓄能器。一般情况下，蓄能器油压为额定值，当系统微量内泄漏时，蓄能器就向系统补油。当油压下降到下限值（仍高于液压缸所需油压），蓄能器上补油行程开关XK2（图中未示出）自动动作，液压泵电机启动，将蓄能器充满油。这时另一停液压泵电机的行程开关XK3动作，使液压泵电机停止，完成系统的自动补油过程，使整个液压系统保持在安全工作油压下。
③ In order to ensure that the pressure of the hydraulic cylinder is not lower than the required oil pressure when it works for a long time, so that the heavy hammer will not drop due to the low oil pressure, a spring accumulator is paralleled in the oil circuit of the hydraulic system. Generally, the oil pressure of the accumulator is the rated value. When there is slight internal leakage in the system, the accumulator will supply oil to the system. When the oil pressure drops to the lower limit (still higher than the required oil pressure of the hydraulic cylinder), the oil replenishment travel switch xk2 (not shown in the figure) on the accumulator will automatically act, and the hydraulic pump motor will start to fill the accumulator with oil. At this time, the travel switch xk3 of the other stop hydraulic pump motor acts to stop the hydraulic pump motor, complete the automatic oil replenishment process of the system, and keep the whole hydraulic system under the safe working oil pressure.

    ④手动操作为提高蝶阀的安全性能，该蝶阀配备了一套手动操作系统，控制阀门的开启与关闭。手动开阀操作：关闭与电磁阀串联的手动阀1——摇动手摇泵一蝶阀缓缓开启（用反作用式电磁阀时，可不关闭手动阀1，本蝶阀的电磁阀为反作用式电磁阀）。手动关阀操作：打开与电磁阀并联的手动阀2——蝶阀在重锤作用下按预定的程序分快关和慢关二程序关闭（手动操作完毕后，必须关闭手动阀2，打开手动阀1至全开，这样才能电动操作，否则电动操作会失控）。
④ Manual operation in order to improve the safety performance of the butterfly valve, the butterfly valve is equipped with a set of manual operation system to control the opening and closing of the valve. Manual valve opening operation: close the manual valve 1 in series with the solenoid valve - shake the hand pump and open a butterfly valve slowly (when using the reaction solenoid valve, the manual valve 1 can not be closed, and the solenoid valve of this butterfly valve is the reaction solenoid valve). Manual valve closing operation: open the manual valve 2 in parallel with the solenoid valve. Under the action of the heavy hammer, the butterfly valve is closed according to the predetermined procedures of fast closing and slow closing (after the completion of manual operation, manual valve 2 must be closed, and manual valve 1 must be opened until it is fully open, so that the electric operation can be carried out, otherwise the electric operation will be out of control).