进口自动再循环阀，最小流量阀，自控回流阀原理慨述 Principle description

自动再循环阀（自控回流阀）是一个独立的系统，能够动态的感知主路流量的变化，随主路流量调整旁通流量。它集止回、流量感知、旁通流量控制、多级减压功能于一身 RETZ The automatic recirculation valve (automatic return valve) is an independent system, which can dynamically sense the change of the main flow and adjust the bypass flow with the main flow. It integrates check, flow sensing, bypass flow control and multi-level pressure reduction functions

其工作原理可以用三种状态来描述 Its working principle can be described in three states

当主阀处于全开位置时（图3a），旁通阀关闭。阀瓣带动操纵杆上升，由杠杆原理，操纵杆使副阀朝关闭方向移动直至完全关闭。其流场分布见图4 When the main valve is in the fully open position (Fig. 3a), the bypass valve is closed. The valve flap drives the operating lever to rise. Based on the lever principle, the operating lever moves the auxiliary valve in the closing direction until it is completely closed. The flow field distribution is shown in Figure 4

当主阀逐渐关闭时（图3b），阀瓣下降，操纵杆和副阀脱离，在压差的作用下，副阀逐渐开启 When the main valve is gradually closed (Fig. 3b), the valve clack drops, the control lever and the auxiliary valve are separated, and the auxiliary valve is gradually opened under the action of differential pressure

当主阀关闭时（图3c），旁通开度最大，满足泵的最小流量。旁通阀具有多级减压功能，其流场分布见图5 When the main valve is closed (Fig. 3c), the bypass opening is the largest to meet the minimum flow of the pump. The bypass valve has the function of multistage pressure reduction, and its flow field distribution is shown in Figure 5

进口自动再循环阀，最小流量阀，自控回流阀泵的保护机理 Pump protection mechanism

离心泵用于锅炉水、冷凝液或其他液体供给时，在泵启动和小工艺流量时需要进行最小流量保护  When the centrifugal pump is used to supply boiler water, condensate or other liquids, the minimum flow protection is required when the pump is started and the process flow is small

由于液体摩擦和压力损失，液体的温度会升高。图1a为典型的温度、压头和流量关系曲线。额定流量点，温度正常，对泵的操作无影响，因为泵内产生的热量随流出泵的液体散发。当工艺流量减少，散热降低，液体温度升高并汽化，过热和蒸汽压会破坏泵的密封、轴承和其他旋转零件 The temperature of the liquid will rise due to liquid friction and pressure loss. Figure 1a shows a typical temperature, head and flow relationship curve. The normal temperature at the rated flow point has no impact on the operation of the pump, because the heat generated in the pump is emitted with the liquid flowing out of the pump. When the process flow decreases, heat dissipation decreases, liquid temperature rises and vaporizes, overheating and steam pressure will damage the seals, bearings and other rotating parts of the pump

图1b与1c为泵产生内部循环流动，发生气穴，破坏叶轮 Figures 1b and 1c show that the pump generates internal circulation flow, which causes cavitation and damages the impeller

泵的三种保护方式 Three types of pump protection

●连续循环系统（图2a）Continuous circulation system (Fig. 2a)

最小需求流量与工艺流量的变化无关。回路经降压孔板直接回储罐。连续的最小流量循环虽然可以很好地保护泵，但是必须泵提供更大的输出功率，造成额外的能量浪费 The minimum demand flow is independent of the change in process flow. The circuit directly returns to the storage tank through the pressure relief orifice. Although continuous minimum flow circulation can protect the pump well, the pump must provide greater output power, resulting in additional energy waste

●控制循环系统（图2b）Control circulation system (Fig. 2b)

控制循环系统由止回阀、流量计、降压孔板、回流控制阀、电磁阀组成。控制循环系统能够提供最小流量保护，当工艺流量大时，回路关闭，没有额外的能量损失。但系统元件多，购买、安装、维护费用高 The control circulation system consists of check valve, flowmeter, pressure reducing orifice, return control valve and solenoid valve. The control circulation system can provide minimum flow protection. When the process flow is large, the loop is closed without additional energy loss. However, there are many system components and the cost of purchase, installation and maintenance is high

●自控回流阀系统（图2c）Automatic return valve system (Fig. 2c)

自控回流阀集止回阀、流量感知元件、旁通控制阀、多级降压的功能于一体。无需动力源和信号源；采用静密封，无外漏；完全的无电连接，属本质安全型；减少了连接的数量，安装、维护费用低 The automatic return valve integrates the functions of check valve, flow sensing element, bypass control valve and multistage pressure reduction. No power source and signal source are required; Adopt static seal without leakage; Complete non electric connection, intrinsically safe; The number of connections is reduced, and the installation and maintenance costs are low

结构与材质 Structure and material

带*为推荐备件旁 * beside recommended spare parts

旁通部件材质 Bypass component material

安装系统 Installing the system

背压阀参数 Back pressure valve parameters

背压阀（图10）装在旁通管线，防止出现“闪蒸”，从而有效地保护阀门和管线。背压阀的结构见图10，通过活塞可以动态地调节旁通管线的背压值。背压阀可以直接安装在旁通出口，也可以安装在储罐的前端 The back pressure valve (Figure 10) is installed in the bypass pipeline to prevent "flash", so as to effectively protect the valve and pipeline. The structure of the back pressure valve is shown in Figure 10. The back pressure value of the bypass pipeline can be dynamically adjusted through the piston. The back pressure valve can be directly installed at the bypass outlet or at the front of the tank