進口自動再循環閥，最小流量閥，自控回流閥原理慨述 Principle description

自動再循環閥（自控回流閥）是一個獨立的系統，能夠動態的感知主路流量的變化，隨主路流量調整旁通流量。它集止回、流量感知、旁通流量控制、多級減壓功能于一身 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種狀態來描述 Its working principle can be described in three states

當主閥處于全開位置時（圖3a），旁通閥關閉。閥瓣帶動操縱桿上升，由杠桿原理，操縱桿使副閥朝關閉方向移動直至完全關閉。其流場分布見圖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

當主閥逐漸關閉時（圖3b），閥瓣下降，操縱桿和副閥脫離，在壓差的作用下，副閥逐漸開啟 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

當主閥關閉時（圖3c），旁通開度最大，滿足泵的最小流量。旁通閥具有多級減壓功能，其流場分布見圖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

進口自動再循環閥，最小流量閥，自控回流閥泵的保護機理 Pump protection mechanism

離心泵用于鍋爐水、冷凝液或其他液體供給時，在泵啟動和小工藝流量時需要進行最小流量保護  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

由于液體摩擦和壓力損失，液體的溫度會升高。圖1a為典型的溫度、壓頭和流量關系曲線。額定流量點，溫度正常，對泵的操作無影響，因為泵內產生的熱量隨流出泵的液體散發。當工藝流量減少，散熱降低，液體溫度升高并汽化，過熱和蒸汽壓會破壞泵的密封、軸承和其他旋轉零件 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

圖1b與1c為泵產生內部循環流動，發生氣穴，破壞葉輪 Figures 1b and 1c show that the pump generates internal circulation flow, which causes cavitation and damages the impeller

泵的三種保護方式 Three types of pump protection

●連續循環系統（圖2a）Continuous circulation system (Fig. 2a)

最小需求流量與工藝流量的變化無關。回路經降壓孔板直接回儲罐。連續的最小流量循環雖然可以很好地保護泵，但是必須泵提供更大的輸出功率，造成額外的能量浪費 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

●控制循環系統（圖2b）Control circulation system (Fig. 2b)

控制循環系統由止回閥、流量計、降壓孔板、回流控制閥、電磁閥組成。控制循環系統能夠提供最小流量保護，當工藝流量大時，回路關閉，沒有額外的能量損失。但系統元件多，購買、安裝、維護費用高 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

●自控回流閥系統（圖2c）Automatic return valve system (Fig. 2c)

自控回流閥集止回閥、流量感知元件、旁通控制閥、多級降壓的功能于一體。無需動力源和信號源；采用靜密封，無外漏；完全的無電連接，屬本質安全型；減少了連接的數量，安裝、維護費用低 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

結構與材質 Structure and material

帶*為推薦備件旁 * beside recommended spare parts

旁通部件材質 Bypass component material

安裝系統 Installing the system

背壓閥參數 Back pressure valve parameters

背壓閥（圖10）裝在旁通管線，防止出現“閃蒸”，從而有效地保護閥門和管線。背壓閥的結構見圖10，通過活塞可以動態地調節旁通管線的背壓值。背壓閥可以直接安裝在旁通出口，也可以安裝在儲罐的前端 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