A plant’s and pipe system’s motor-operated valves (MOV) are crucial components. These valves, typically massive, are utilized in various applications, including pump discharge. The motor-operated control valves, also known as on/off valves, are used to fully or partially open or close the valves in the pipes. For instance, when fluid management is not necessary, motor-operated valves are used to wholly or partially cease fluid flow in cooling water lines, process pipes, and other piping systems. These valves aren’t utilized for throttling because their primary function is for On-Off service applications.
Motor operated valve
A motor-operated valve is any valve activated by an electric actuator, such as a standard ball valve or any other valve (MOV). The MOV is typically employed as an isolation valve for machinery that needs frequent access. The MOV is also utilized on any valve when manually opening or closing requires significant energy. There is no specific justification for MOV use other than operational simplicity.
The valve, a gearbox, and an electric motor actuator make up the conventional MOV structure. The output thrust component received the motor’s rotation through a gear mechanism. The gear mechanism in the gearbox then receives the output thrust and rotates the valve stem.
The Motor Operated Valve Design
This course focuses on the operation of Safety-Related Motor-Operated Valves under Design-Basis conditions in the classroom and laboratory.ISU has been able to create and sustain a well-regarded technical training program since 2004, primarily focusing on teaching staff members of the US Nuclear Regulatory Commission. ISU’s ESTEC now offers this training to engineers, senior technicians, and consultants in the nuclear industry to give them a complete understanding of how MOVs work in atomic service.
The course covers the course’s performance, design basis verification, regulatory elements of MOV testing and maintenance, hands-on experience with MOV actuators, and in-service testing of MOVs. The instructors for this course are business specialists who worked at the Idaho National Laboratory of the US Department of Energy on the front edge of MOV engineering. With more than 52 years of combined experience in nuclear energy reactor operations, motor-operated valve design basis research, commercial plant licensing, and NRC MOV inspection, the instructors Kevin G. DeWall and Mark R. Holbrook are qualified to teach. They have the specialized knowledge required to deliver this extensive training.
Types of the motor-operated valve
· Accurate flow valves
Precision flow valves offer precise flow control and are superior to an inching valve.An inching valve’s motorized actuator operates in stages set by the controller, such as 5 percent and 10 percent opening steps. With so much room for error, flow regulation may also be made in 5–10% brackets.
Unlike conventional motor-operated valves, precision flow valves offer the correct feedback from the field to the controller to give continuous flow control. Examples include GT’s steam and water injection valves to regulate NOx.
· Open / Close valves
These valves are on/off switches to turn on or off the flow. Here, perfect flow management is not the primary objective. Motors operate large actuators that open and close enormous valves.
· Inching valves
Comparatively, these valves provide more accurate flow control than on/off valves. A motorized actuator makes it easier for the valve to open and close gradually, giving you some flow control. Examples include:
- Boiler main steam valves
- Boiler IBD valves
- Boiler reflux lines
- Boiler start-up vents
Launch of a motor-operated valve (MOV)
Let’s look at configuring two used motor-operated valve configuration settings: open and shut feedbacks and torque values. After entering the password and changing the four options, we may access the menu.
Motor-operated valves include gate, ball, butterfly, and other valves with actuator control. Engines and valves may have diverse designs. An electric motor mounted on the valve and gear attached to the valve stem allows the valve to open or close when the engine is running. This MOV requires a motor managed by an actuator from the local panel or the control room. Engineers must work together to develop and purchase motor-operated valves, pipelines, electrical, instrumentation, process, and supplier.
Utilizations for motor-driven valves
- Valves placed in distant, hazardous, or difficult-to-access locations;
- Whenever a frequent operation is necessary.
The motorized control valve and motor-powered valves are often used for applications that require complete opening and shutting. They are occasionally also employed for position control, though.
Differences between motorized on/off valves and control valves
- Control valves respond more quickly than motorized valves do.
- Analog control elements are often found in control valves, whereas digital control elements are in motorized driven valves. Unlike motorized valves, control valves can control any authority, including pressure, flow, temperature, etc.
- Control valves are typically employed in closed-loop controls instead of open-loop commands, which frequently use motorized valves.
- Control valves use to obtain precision control. There are numerous actuator-controlled motor-controlled valves, including Gate, Ball, Butterfly, etc. The use of motorized valves for precise control, however, is uncommon.
- There are several motor and valve designs available. An electric motor is attached to the valve and gear-mounted to the valve stem, causing the valve to open or shut when the motor is running. An actuator must activate the engine for this MOV under the direction of a local panel or a control room. To develop and acquire motor-powered valves, pipelines, electrical, instrumentation, and process engineers must collaborate.