Valves Instumentation and Control.ppt

Valves, Instrumentation, and Control Process Design CEN 574 Spring 2004 Outline Types of valves Components of valves Instrumentation: on-line meters Process control review Valves, Instrumentation, and Control Learning Objectives At the end of this section, you should be able to… Describe the major types of valves, their operation and characteristics, and draw their standard symbols on a PID. Select an appropriate valve for a specific application. Identify the function of the major components of a valve. Select trim and K List the four most commonly measured variables and draw the symbols for those meters on a P ID. Describe the principals of measurement. Define the variables involved in an PID loop and draw appropriately on a PID. Define tuning. List the common process problems that lead to unstable PID loops. References Chapter 15 in Turton et al., Analysis, Synthesis, and Design of Chemical Processes. Process Engineers: Take Control! Cecil L. Smith. Chemical Engineering Progress. August 2000. Valve Types Ball Valve Butterfly Valve Gate Valve Globe Valve Check Valve Parts of a Valve 3.?End fitting: must be specified when buying the valve - butt weld end, compression flange, pipe thread, quick disconnect 4.?Material: closure member, housing, seat – stainless steel 5.?Packing/seals: seals stem, replaced 6.?Seat: where the closure members seals against the valve housing Ball Valve Gate Valve Butterfly Valve Check Valves Globe Valve Rupture Disk (not a valve – ruptures at a set pressure) Valve Symbols Instrumentation- Form groups of two.- List as many process conditions that can be measured on-line as you can.- List the four most common. Instrumentation Most commonly measured process conditions: temperature, level, pressure, flow rate, pH. Other variables include composition, moisture, specific gravity, viscosity, dissolved oxygen. Temperature Thermocouple Two wires of different metals welded together at the end When the junction is heated a sm