In any industries, the shop floor contains many processes that are linked together to get a desired product. In order to achieve the desired product, the intermediate processes must have to be functioned in a controlled manner. These processes are designed to do their own desired task under controlled system. The control valve is the one that is used to control the independent parameters such as temperature, pressure, volume, flow rate, etc. at each sub systems in a shop floor.
There are many changes/disturbances in the desired product from the designed product even after the system is controlled. The design and the proper selection and maintenance of the control valve is the only key factor that alters the product nature. In order to achieve the ideal product, the design of control valve is mandatory.
This practical task gives scope to this course on Control valve sizing, selection and maintenance; this enables the student to gain detailed study on design of controller, types and selection of control valves, calculations, performance and maintenance are also covered. This advanced course comes under process engineering.
The technical profession in the shop floor and those who are interested to gather designing concepts of control valves can learn many concepts by this course.
WHO SHOULD COMPLETE THIS COURSE
- Instrumentation engineers
- Process engineers
- Design technicians
- Consulting Engineers
- Engineering managers
- Project Engineer
COURSE OUTLINE
BASIC SIZING FOR LIQUIDS:
- Selection process and formulations
- Selection steps and sizing of control valves
- Valve coefficient
- Purpose,
- Pressure recovery factors
- Application of control valves
- Liquid sizing equations for determining volumetric flow rate
- Metric and SI formulae
- Valve characteristics
BASIC SIZING FOR GASES AND VAPORS:
- Selection steps and sizing of control valves for gas
- Saturated steam
- Superheated steam
- Determination of valve coefficient
- Gaseous and vapor sizing equations for determining volumetric flow rate
- Metric and si formulae
INHERENT AND INSTALLED FLOW CHARACTERISTICS
- valve characteristics
- butterfly disc shapes
- butterfly valve – inherent characteristic
- high performance characteristics
- flow characteristics
- globe valve characteristics
- cage valve characteristics
- various ball valve characteristics
- simple calculation data
- inherent characteristics
- installed characteristics
- overall process control loop
- closed loop control and controller
- importance of loop gain
- non-linear response conversion of gain to percentage of controller input range
- process pressure ratio and conclusion
ACTUATORS AND POSITIONERS
- purpose
- principles of actuators for control valves
- issues of size
- force and speed matched to valve type
- control valve design considerations
TYPES OF ACTUATORS
- Pneumatic actuator types –piston and diaphragm
- Fixed spring, rotary
- Rack and pinion
- Rotary vane
- Electrical actuators – on/off control
- Modulated control
- Solenoid type
- Hydraulic actuators for large valves
- Actuator accessories
CAVITATION AND FLASHING
- Fundamental concepts on Cavitation
- Static and dynamic pressure profiles
- Multistage pressure reduction through the valve trim
- Cavitation mechanisms
- Effects of flashing
- Damage
- Velocity and noise
- Incipient cavitation
- Diffuser plate and choke
- Trim selection guide
CAVITATION CONTROL
- problem characteristics
- Types and cavitation control parameters
- Anti-cavitation trim
- Cavitation elimination
NOISE PREDICTION AND TREATMENT
- Control valve noise Sources
- Treatment
- Prediction of noise
- Methods
- Low noise trim
- Diffuser plates
- Globe valve trim selection
- High pressure drop applications
- ED disk stack
- Low noise retainers
- Examples of noise reduction,
- Noise treatment and accessories
- Q-ball for noise attenuations and anti-cavitation
- Noise source treatment
- Chokes
- Disk stack technology
- Pressure balanced trim
MATERIALS OF CONSTRUCTION
- Control valve materials
- Overview of material selection issues
- Standard control valve body materials
- Typical materials of construction for body and valve trim
- Recognize issues of corrosion and wear, valve trim materials
- Seating materials for tight shut off vs durability
- Problems of leaks from seals
- Applications of bellows seals for toxic materials
MAINTENANCE ISSUES
- Tasks involved in valve maintenance
- Installation features relevant to good maintenance
- Recognize the setting up and testing tasks for valves
- Methods of detection of backlash and stiction in the valve drive
- Potential advantages of using smart positioners and diagnostic software tools.
PRINCIPLES OF PRESSURE
- Hazards of overpressure
- Causes and consequences,
- Basic terminology
- European standards
- Pressure types
- ASME code requirements
PRESSURE RELIEF SYSTEM
- Requirements
- Purpose
- Relief systems
- layer of protection
- use and purpose of relief system
PRESSURE RELIEF VALVES
- Safety valves- types and performance issues
- Sizing principles and equations
- Calculations with examples
- Superimposed and built – up back pressure
- Balanced pressure relief valve operation and construction
- Balanced spindle design
- Pilot operated type
- Back pressure effects on pilot operated valve
DESIGNING CONCEPTS AND ISSUES
- Outline of relief design procedure
- Sizing reliefs – determining relief rates
- Vent area
- Size of valve
- Sizing formulae and equations for gaseous and liquid flow
- Specification and installation issues
- Problem of chatter
- Rupture discs
- Rupture pins
- Prv conclusions
