Control valves are used in many processes to control flow, pressure, temperature or other variables. The type of valve used will depend on the size of the pipe, the overall pressure that the system operates, the flowing media, process conditions, and other factors.
Process plants consist of hundreds, or even thousands, of control loops all networked together to produce a product to be offered for sale. Each of these control loops is designed to keep some important process variable such as pressure, flow, level, temperature, etc. within a required operating range to ensure the quality of the end product. Each of these loops receives and internally creates disturbances that detrimentally affect the process variable, and interaction from other loops in the network provides disturbances that influence the process variable.
To reduce the effect of these load disturbances, sensors and transmitters collect information about the process variable and its relationship to some desired set point. A controller then processes this information and decides what must be done to get the process variable back to where it should be after a load disturbance occurs. When all the measuring, comparing, and calculating are done, some type of final control element must implement the strategy selected by the controller.
Principles of Operation
The most common final control element in the process control industries is the control valve. The control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point.
Control valves may be the most important, but sometimes the most neglected, part of a control loop. The reason is usually the instrument engineer’s unfamiliarity with the many facets, terminologies, and areas of engineering disciplines such as fluid mechanics, metallurgy, noise control, and piping and vessel design that can be involved depending on the severity of service conditions.
Any control loop usually consists of a sensor of the process condition, a transmitter and a controller that compares the “process variable” received from the transmitter with the “set point,” i.e., the desired process condition. The controller, in turn, sends a corrective signal to the “final control element,” the last part of the loop and the “muscle” of the process control system. While the sensors of the process variables are the eyes, the controller the brain, then the final control element is the hands of the control loop. This makes it the most important, alas sometimes the least understood, part of an automatic control system. This comes about, in part, due to our strong attachment to electronic systems and computers causing some neglect in the proper understanding and proper use of the all important hardware.
What is a Control Valve..
Control valves automatically regulate pressure and/or flow rate, and are available for any pressure. If different plant systems operate up to, and at pressure/temperature combinations that require Class 300 valves, sometimes (where the design permits), all control valves chosen will be Class 300 for interchange-ability. However, if none of the systems exceeds the ratings for Class 150 valves, this is not necessary.
Globe valves are normally used for control, and their ends are usually flanged for ease of maintenance. Depending on their type of supply, the disk is moved by a hydraulic, pneumatic, electrical or mechanical actuator. The valve modulates flow through movement of a valve plug in relation to the port(s) located within the valve body. The valve plug is attached to a valve stem, which, in turn, is connected to the actuator.
Control Valve Arrangement
The image below shows how a control valve can be used to control rate of flow in a line. The “controller” receives the pressure signals, compares them with pressure drop for the desired flow and if the actual flow is different, adjusts the control valve to increase or decrease the flow.
Comparable arrangements can be devised to control any of numerous process variables. Temperature, pressure, level and flow rate are the most common controlled variables.
Valve Materials
We offer valves of various materials which can meet your needs on diverse occasions. Come get your valves right now!
Our Valves materials can be the following grade, another grade is also available on request.
Applications
Valves are found in virtually every industrial process, including water and sewage processing, mining, power generation, processing of oil, gas and petroleum, food manufacturing, chemical and plastic manufacturing and many other fields.
Transport
Refinery
Thermal Power Plant
Steel Plant
Water Supply
Natural Gas Pipeline
Quality Control
A valve can be described as a mechanism that controls the passage of liquids through a pipe. Research states that valves being manufactured in China are amongst the top valve competitors in the valve industry.
Nondestructive Test
Radiography Inspection guarantees no failures inside of the castings or forgings. Ultrasonic inspection acts an alternative of inspection. Dye penetrant testing and magnetic particle testing can examine surface failures on castings and forgings.
Cryogenic Treatment
-196 ℃ Cryogenic Treatment System is a basic treatment for LNG usage valves or similiar applications.
Leakage Test
Leak testing is a procedure that inspectors use to determine whether an object or system is functioning within a specific leak limit.
Chemical Analysis
All our materials are strictly made under supervision of ladle analysis instrument in the foundries and inspected by high precision spectroanalysis instrument when they arrive in our plant.
Mechanical Properties Test
All mechanical properties test will act before we use the materials to secure the performance and safety.
Heat Treatment
Up to 1200 ℃ electric furnance provide an availability of various heat treatment cycles.
Why Do I Need Wear Parts?
“Wear” is the last thing any business wants to experience with their machines. Apart from its unpleasant physicality, it could also be a sign that means your parts and/or components are about to break. You need wear parts to help prevent or prolong the wearing out of these parts and components – and that could be any type of wear parts such as pipes, liners, plates, etc.What Kinds of Wear Plates Do You Offer?
Here at Sunny Steel, we put emphasis to the primary kinds and types of wear pipes and fittings – they include:- Ceramic Liner pipes and fittings
- Ceramic tile lined pipes and fittings
- Ceramic sleeve lined pipes and fittings
- Cast basalt lined pipes and fittings
Merits and Salient Features
- Extremely High Resistant to Abrasion, Erosion and Corrosion.
- Resistant to most of the Chemicals, Alkalis and Acids.
- Very Long life
- Less Down time and Maintenance Cost.
Thermal power stations – raw coal chutes/ hoppers, feed bunker/coal bunker, ash pits, crushers, bottom ash, disposal slurry, dust lines/ bends, pipeline/bends, fly ash. Trenches below hopper and pipelines, pulverized coal piping.
Cement plants – dynamic air separators, raw mill ducts/ chutes, drag chain conveyor, grate cooler housing, air separator/ cyclones, coal handling, coal hopper/ chutes, cement conveying, slurry lines/ bends lines/ bends, discharge boxes / bankers, lime/silica hoppers/chutes, chain conveyor housing, mixers/nozzles, coal ventury.
Steel plants – coke sorting unit, coal bunkers / sinter bunkers, lime bunkers, coke breeze, sinter plant cyclones, sinter plant flow conveyors, iron slurry line, thick slurry lines, air lift pipes, telescopic pipes, granulated slag, hot mill flume.
Coal washeries – coal washing plants, coal transportation, conveyor chutes/pipes, floatation cells, media sumps, centrifuges, cyclones, sieves.