Analysis and comparison of electric butterfly valve valve drive mode

Analysis and comparison of electric butterfly valve valve drive mode

In the field of environmental protection, water conservancy, petrochemical, metallurgy, papermaking, electric power, aerospace, pipeline, industrial equipment, industrial processing and other fields need to use a large number of valves to control fluid movement. As a control valve open, close or part of the switch drive device is usually called a valve actuator or valve actuator. Actuator as a valve control of the terminal actuator, its reliability, controllability and functionality of the advantages and disadvantages, will have a direct impact on the regulation, control of the results of the success or failure and the safety of the equipment, and constraints on the overall level of automation to improve.

Traditional actuators are divided into electric, pneumatic, and hydraulic three kinds, and the derivation of gas-liquid joint, electro-hydraulic joint drive. Each drive has its own advantages and disadvantages, this article briefly explains the electric, pneumatic, hydraulic three drive advantages and disadvantages, to facilitate a quick understanding.

Electric actuator

Electric actuator, as the name suggests, is powered by electricity, using a single-phase or three-phase motor to drive gears or worm gears to output linear or rotary motion. Electric actuators can output a relatively constant driving force, have strong resistance to deviation, higher control accuracy than pneumatic actuators, and can be automatically held without the need for other auxiliary systems. Electric actuators have simple operation, easy long-distance control, but their structure is complex, prone to failure, often have low positioning accuracy, issues such as over-opening, overloading, motor burning, gearbox wear, etc., leading to high maintenance costs. Frequent adjustments can cause motor heating and gear wear. Additionally, electric actuators run slowly, have difficulty achieving high driving forces, and face challenges such as difficulties in over-protection realization and poor positioning.

Analysis and comparison of several types of valve drive: 1. Manual drive: Requires manual operation for opening and closing valves. 2. Pneumatic drive: Uses compressed air to operate valves, providing quick and efficient control. 3. Electric drive: Utilizes electric power to control valve operation, offering precise and automated functionality. 4. Hydraulic drive: Relies on hydraulic fluid to drive valve movement, suitable for high-pressure applications. 5. Solenoid drive: Employs electromagnetic force to actuate valves, enabling fast response times and remote control capabilities.

Second: 气动执行器

Pneumatic actuator actuator and regulator is a unified whole, its actuator has a thin film type, piston, toggle fork and rack and pinion type. Adopting gas as power medium has the advantage of high safety and low requirements on the use environment. However, due to the compressibility of the gas, the relatively low stiffness of the pneumatic actuator response is slow, poor resolution, low control accuracy, weak resistance to deviation, applied in the dynamic force or friction in the case of a large number of situations, it is very easy to cause undesirable vibration of the equipment. And its energy to weight ratio is poor, low power density, large driving force of the pneumatic actuator is extremely complex, bulky and expensive.

Hydraulic actuator

Ordinary hydraulic actuators use high-pressure oil as a driving force, with a large load capacity and high regulation accuracy, but require a large independent oil supply equipment, leading to a relatively high maintenance workload. Hydraulic actuators have vane, rack and pinion, and spiral structures, each with its own advantages and disadvantages. Vane structures have low load-bearing capacity and oil leakage issues; rack and pinion types have high load-bearing capacity and simple structures but are bulky; spiral actuators offer high positioning accuracy but have high processing difficulty. The image below shows a rack and pinion actuator installed on a valve. Traditional hydraulic actuators typically require a hydraulic station, resulting in large volume, long hydraulic piping, throttling loss, and inconvenient maintenance.

Four: 电液执行器

Electro-hydraulic actuator is a hydraulic actuator derived from a power device, integrating hydraulic, control, electromechanical, computer, communications, and other technologies. It enables fast, stable positioning of controlled objects for accurate control, used in various valve driving and control applications. It combines the simplicity of electric operation with the power of hydraulic systems, offering fast response speed, high control accuracy, high output power, and compact structure. It overcomes issues of low control accuracy in pneumatic actuators and poor controllability in electric actuators. There are two main types: one controlled by a servo valve in an open hydraulic system, and the other controlled by motors in a closed hydraulic system for precise regulation of controlled objects.

The new electro-hydraulic actuator structure is simple, compact, small in size, with smooth transmission, capable of obtaining a large output torque, convenient speed adjustment, easy control, easy overload prevention, overall inexpensive, easy to maintain, and applicable to a wide range of characteristics.

Analysis and comparison of several types of valve drive control box integrated hydraulic micro-power unit and control board, making the entire actuator intelligent, miniaturized. Electro-hydraulic actuator is an important control element of the industrial automatic control system, can be adjusted to the valve pressure, flow, temperature, etc., a large number of applications in the chemical industry, petroleum, metallurgy, electric power, coal and other industrial process control systems. Electro-hydraulic actuator development towards small, lightweight, energy efficient, high reliability trend.