PROCESS INSTRUMENTATION Piping & Instrumentation Diagram Mrs Anis Atikah Ahmad Email:anisatikah@unimap.edu.my Tel: 04-976 3245

OUTLINE Introduction to P & ID Introduction to Process Control Instrumentation Symbology Instrumentation Numbering Process Control Variety

PFD

P&ID

1. Introduction to P & ID Also known as “PROCESS & INSTRUMENTATION DIAGRAM” Detailed graphical representation of a process (i.e piping, equipment, and instrumentation) necessary to design, construct and operate the facility. Common synonyms for P&IDs include Engineering Flow Diagram (EFD), Utility Flow Diagram (UFD) and Mechanical Flow Diagram (MFD).

1.1 Component of P & ID 2. Process Control Loop (if any) 1. All PFD components 2. Process Control Loop (if any) 3. All instruments (eg: transmitter, indicator, alarm) 4. Instrumentation Tagging & Numbering

2. Introduction to Process Control Component of Process Control Measuring device (Sensor & transmitter) Controller I/P Transducer (if FCE is control valve) Final Control Element (Control Valve, Pump, Heater)

2. Introduction to Process Control Basic Loop Set point Controller Transmitter Fluid Fluid Orifice (Flow Sensor)

2. Introduction to Process Control Basic Loop Process Sensing Element Measuring Element Transmit Control Element Final Control Transmitter Sensor Control Valve/ Heater/ Pump Controller

2.1 Sensor SENSORS (Sensing Element) A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which can be read by a voltmeter. For accuracy, all sensors need to be calibrated against known standards.

2.1.1 Temperature Sensor Thermocouple Cheaper than RTD Durable React faster to changes in temperature  Can measure a bigger range of temperatures

2.1.1 Temperature Sensor Resistance Temperature Detector (RTD) Readings are more accurate and more repeatable Expensive

2.1.2 Flow Sensor Turbine Flow Meter Very accurate ( commonly used to prove other meters.) Not usable in dirty streams or with corrosive materials

2.1.2 Flow Sensor Magnetic Flow Meter Flow rate unaffected by fluid density, consistency, viscosity, turbulence, or piping configuration. Highly accurate Corrosion-resistant using Teflon liner and platinum electrodes Wide flow measuring ranges & no pressure drop    Costly, relative to other flow meter types.    Cannot be used for gas flow measurements

2.1.2 Flow Sensor Orifice Flow Meter Fabrication simple and inexpensive. No limitations on the materials of construction, line size and flow rate

2.1.2 Flow Sensor Venturi Meter Can be used for high/extreme temperature Highly expensive Larger and heavier to handle Can be used for gas & liquid

2.1.3 ASSIGNMENT Discuss the function of each temperature and flow sensor in slide 11-16. Must include the discussion on how they operate (any principle used) Deadline: 24 November 2016

2.2 Transmitter A transmitter measures the process variable and transmits the information to a central location where the comparison takes place Differential Pressure Transmitter Pressure Transmitter

Indicating Controller Controller is a device which monitors and affects the operational conditions of a given dynamical system. The operational conditions are typically referred to as output variables of the system which can be affected by adjusting certain input variables. Recording Controller Indicating Controller

2.4 I/P Transducer A device that converts electric signal to pneumatic signal. Control Valve

2.5 Final Control Element Final Control Element is a device that directly controls the value of manipulated variable of control loop. Final control element may be control valves, pumps, heaters, etc. Pump Control Valve Heater

2.6 Process Control Structure Example 1 Figure below shows the liquid vessel for boiler system. The control objective in this system is to maintain the vessel temperature at 120 oC. The heater will be switched off when the temperature reached the desired temperature. Draw feedback control loop for the system. TC V-100 What is the final control element in this system? -HEATER Fluid in TT Fluid out V 100

2.6 Process Control Structure Exercise 1: Draw TWO control loops to control level L3 and L5 at the desired level. LT 1 LIC 1 LCV-100 close when level reached L 3 LCV-100 open when level below L3 L3 LCV-100 L2 TK-100 L1 LT 2 LIC 2 V-100 L5 LCV-101 LCV-101 close when level reached L5 LCV-101 open when level below L5 L4

2.6 Process Control Structure Answer 2 LIC 1 LT 1 LIC 1 L3 LCV-100 close when level reached L 3 LCV-100 open when level below L3 LT 1 LCV-100 L2 TK-100 L1 LIC 2 V-100 L5 LT 2 LIC 2 LT 2 LCV-101 L4 LCV-101 close when level reached L5 LCV-101 open when level below L5

3. Instrumentation Symbology Instruments that are field mounted. -Instruments that are mounted on process plant (i.e sensor that mounted on pipeline or process equipments. Field mounted on pipeline

3. Instrumentation Symbology Instruments that are board mounted -Instruments that are mounted on control board.

3. Instrumentation Symbology Instruments that are board mounted (invisible). -Instruments that are mounted behind a control panel board.

3. Instrumentation Symbology Instruments that are functioned in Distributed Control System (DCS) - A distributed control system (DCS) refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component sub-system controlled by one or more controllers. The entire system of controllers is connected by networks for communication and monitoring.

3. Instrumentation Symbology

3. Instrumentation Symbology FC Flow Controller PT Pressure Transmitter FE Flow Element (Orifice Plate/) Venturi tube FI Flow Indicator FT Flow Transmitter LC Level Controller FS Flow Switch LG Level Gauge FIC Flow Indicating Controller LR Level Recorder FCV Flow Control Valve LT Level Transmitter FRC Flow Recording Controller LS Level Switch LIC Level Indicating Controller PC Pressure Controller LCV Level Control Valve PG Pressure Gauge LRC Level Recording Controller PI Pressure Indicator PR Pressure Recorder

3. Instrumentation Symbology PS Pressure Switch TI Temperature Indicator PIC Pressure Indicating Controller TR Temperature Recorder PCV Pressure Control Valve TS Temperature Switch PRC Pressure Recording Controller TC Temperature Controller PDI Pressure Differential Indicator TT Temperature Transmitter PDR Pressure Differential Recorder PDS Pressure Differential Switch PDT Pressure Differential Transmitter

3. Instrumentation Symbology Example

3.1 Signal Line Symbology Signal Lines Symbology

4. Instrumentation Tagging & Numbering XYY CZZLL X represents a process variable to be measured. (T=temperature, F=flow, P=pressure, L=level) YY represents type of instruments. C designates the instruments area within the plant. ZZ designates the process unit number. LL designates the loop number.

4. Instrumentation Tagging & Numbering LIC 10003 L = Level shall be measured. IC = Indicating controller. 100 = Process unit no. 100 in the area of no. 1 03 = Loop number 3

4. Instrumentation Tagging & Numbering FRC 82516 F = Flow shall be measured. RC = Recording controller 825 = Process unit no. 825 in the area of no. 8. 16 = Loop number 16

Various type of process control strategies Feedback Control Feedforward Control Ratio Control Cascade Control Split Range Control

Feedback Control One of the simplest process control schemes. A feedback loop measures a process variable and sends the measurement to a controller for comparison to set point. If the process variable is not at set point, control action is taken to return the process variable to set point. Advantage: corrective action occurs as soon the CV deviates from setpoint. Disadvantage: not provide predictive control action to compensate for the effects of known or measurable disturbance Parameter being measured: Controlled Variable ( level of the water in the boiler)

Parameter being measured: disturbance variable (steam flow rate) Feedforward Control Basic concept: to measure important disturbance variables and take corrective action before they upset the process. Parameter being measured: disturbance variable (steam flow rate)

Feedforward Control (cont.) Feedforward control is normally used in combination with feedback controller. Controller with summing functions are used in these combined systems to sum up the input from both the feedforward loop and the feedback loop, and send a unified signal to the final control element. Feedforward plus feedback controller

Ratio Control Ratio control is used to ensure that two or more flows are kept at the same ratio even if the flows are changing. FIC FF FT FT Water Acid 2 part of water 1 part of acid

Cascade control Cascade Control uses the output of the primary controller (master) to manipulate the set point of the secondary controller (slave) as if it were the final control element. Used when the disturbances are associated with manipulated variable.

Split Range Control Output of a controller is split to two or more control valves. The diagram shows pH adjustment; part of waste water treatment process. The process shall be maintained at pH 6. When the process liquid states below pH 6, CV-102 will be opened to dosing NaOH to the tank TK-100. When the process liquid states above pH 6, CV-101 will be operated to dosing HCl. CV-102 TK-102 (base feed tank) pHIC pHT 1 CV-101 TK-100 (pH adjustment tank) TK-101 (acid feed tank)

Exercise… Identify type of control loop used below. V-100  Y PT PIC PT FC V-100 Process variable need to be controlled = Pressure FT