ABOUT I.O.C.L.IOCL is the India’s flagship national oil company.IOCL is the 18th largest co. in the world & the no. 1 Petroleum trading co. in Asia Pacific Region.IOCL is the top ranked co. among both private &public sectors at 116th position in the worldwidelist.
FLOW DIAGRAM OF PANIPAT REFINARY
ABOUT INSTRUMENTATION Instrumentation is used in almost every industrial process and system, where consistent and reliable operations are required.Instrumentation provides the means of monitoring, recording and controlling a process to maintain it at a desired state. A typical industrial plant such as an electric generatingstation (figure-Electrical Generating System) yield many process variables that have to be measured
MAIN CONTROL SYSTEM IN THIS SYSTEM MAN POWER IS USED. THE OPERATORS IN THE CONTROL ROOMKEEP EYE ON THE PLANT AND IF ANY ALARMOCCURS THEY ORDER THE FIELD WORKERS TO TAKE ACTION.
Temperature Measurement Scales (°F) = 9/5*(°C) +32(°C) = 5/9*[(°F) –32](°F) = (°R) – 459.67(°C) = (K) – 273.15 Methods of Temperature Measurement1.Thermocouples2.Thermistors3.Electrical resistance change (RTD)4.Pyrometers
THERMOCOUPLEWhen 2 dissimilar metals are joined together to form a junction, an emf is produced which is proportional to the temperature being sensed.The magnitude of emf depends on the junction temperature.
THERMISTOR The resistance of thermistors decrease with increases in temperature. The operating range can be -200°C to + 1000°C The thermistors can be in the shape of a rod, bead or disc.
Resistance Temperature Detector- RTDRTD (Resistance Temperature Detector) is a temperaturesensitive resistor.It is a positive temperature coefficient device, which meansthat the resistance increases with temperature.The resistive property of the metal is called its resistivity. PLATINUM WIRE RTD linear temperature sensors Resistance vs temperature characteristics are stable and reproducible
Platinum Scale ( 0 to 100 °C )
Wheatstone Bridge TemperatureDetector for an RTD
RELATION GRAPH BETWEENTHERMISTOR,RTD,THERMOCOUPL E
PYROMETER Pyrometry is a technique for measuring temperaturewithout physical contact An apparatus for measuring high temperatures that usesthe radiation emitted by a hot body as a basis formeasurement.Radiation pyrometersOptical Pyrometers OPTICAL PYROMETER basic principle of using the human eye to match the brightness of the hot object to the brightness of a calibrated lamp filament inside the instrument
Level Measurement IntroductionThere are multiple technologies availablein the market to measure level. Each and every technology works, when applied appropriately
Different types of Level Measurement TechniquesDifferential Pressure typeCapacitanceDisplacers / FloatsBubbler
Differential pressure type - A DP is used to transmit the head pressure that the diaphragm senses due to the height of the material in the vessel multiplied by a density variable. Advantage:- the most frequently used device for the measurement of levelis a differential pressure transmitter. Using DP for level is really an inferential measurement.DIFFERENTIAL PRESSURE
Closed TankLevelMeasurement Open Tank Level Measurement
Capacitance - A capacitance transmitter which convertscapacitance signals input to a standard 4-20 mA output.Together with a capacitance probe, the tx is used tomeasure a continuous level or interface of liquidsAdvantage:-Accurate level measurementindependent of sticky or crystalline cotaing or varying moisturecontent of granulars. Capacitance Type Level measurement
Displacers/Floats- when a body is immersed in a fluid it losesweight equal to that of the fluid displaced. By detection of theapparent weight of the immersed displacer, a level measurementcan be inferred. When the crosssectional area of the displacer and the density of the liquid is constant, then a unit changein level will result in a reproducible unit change in displacer weight. DISPLACER/FLOAT
BUBBLER LEVEL MEASUREMENT SYSTEM If the process liquid contains suspended solids, or is chemically corrosive or radioactive, it is desirable to prevent that fluid from coming into direct contact with the level transmitter. In these cases, a bubbler level measurement system can be used.
Bubbler Level Measurement System
Pressure MeasurementPressure:-means force per unit area exerted by a fluid on the surface of the container. Absolute pressure:- means fluid pressure above thereference value of a perfect vacuum or the absolute zero pressure.Gage pressure:- represent the value of pressure above the reference value of atmospheric pressure. It is the difference between the absolute and local atmospheric pressure. The atmospheric pressure at sea level is nearly 14.7 lb./in square (PSI) or 1.013 X 100000 N/M square (Pa) or 760 mmHg.
we have the pressure and level dependency of:P = S .HwhereP = Pressure (Pa)S = Weight density of the liquid (N/m3)H = Height of liquid column (m)The level of liquid inside a tank can be determined from the pressure readingat the base of the tank, if the specific gravity of the liquid is constant.
Types of measurementManometers :- The difference in levels h between thetwo limbs is an indicator of the pressure difference (P1-P2) between the two limbs. If one of the pressures, say that applied to limb2, is atmospheric, the difference gives the gage pressure applied to limb1. h = (P1-P2)/p p being the mass density of the liquid.
Bourdon Tube :- The cross-section of the tube, due topressure, tends to round out. The tube uncoils since theinner and outer arc lengths remain almost equal to their original lengths. The motion of the end of the tube amplified & indicated by a pointer moving on calibrated scale.
Diaphragm Elements :-Elastic diaphragm converts pressure input into deflection or displacement.
Flow Measurement Orifice meter Venturimeter Flow nozzle Orifice meter-Based on Bernoullis principle. Orifice plate- inserted to pipe to create a partial restriction to flow. Pressure before orifice plate rises and pressure after it reduces but velocity increases.
Types of orifice plateConcentric : The concentric orifice plate is usedfor ideal liquid as well as gases and steamEccentric : used for measuring fluid containingsolids, oil containing water and wet steamSegmented : used for colloidal and slurry flowmeasurement
venturimeter -Throat to diameter ratio 0.25 to 0.75Made of cast iron, gun metal, stainless steelMay be circular, square or rectangular
where high permanent pressure loss is not tolerable, aventuri tube (Figure 7) can be used. Because of itsgradually curved inlet and outlet cones, almost nopermanent pressure drop occurs.This design also minimizes wear and plugging by allowingthe fluid flow to sweep suspended solids through withoutobstruction.
FLOW NOZZLE A flow nozzle is also called a half venturi with flow characteristics between an orifice plate and a venturi tube. Figure 8 shows a typical flow nozzle installation. nozzles are widely used for flow measurements at high velocities
PLC(programming logic control) Programmable logic controllers are the most widely used electronic devices in the control of production and assembly process in most automated factories due to its simplicity and versatility. Initially designed to replace relay logic boards Sequence device actuation Coordinate activities Accepts input from a series of switches Sends output to devices or relays
Components Central Processing Unit (CPU)- It is a micro- controller based circuitry. The CPU consists of following blocks : Arithmetic Logic Unit (ALU), Program memory Process image memory (Internal memory of CPU) Internal timers and counters Flags CPU performs the task necessary to fulfill the PLC functions. These tasks include Scanning, I/O bus traffic control, Program execution, Peripheral and External device communication, special functions or data handling execution and self diagnostics. Input Output Modules-These modules act as interface between real-time status of process variable and the CPU. Analog input module : Typical input to these modules is 4-20 mA, 0-10 V Ex : Pressure, Flow, Level Tx, RTD (Ohm), Thermocouple (mV) Digital input module : Typical input to these modules is 24 V DC, 115 V AC, 230 V AC Ex. : Switches, Pushbuttons, Relays, pump valve on off status
These modules act as link between the CPU and the output devices inthe field. Analog output module : Typical output from these modules is 4-20mA, 0-10 V Ex : Control Valve, Speed, VibrationDigital output module : Typical output from these modules is 24 V DC,115 V AC, 230 V AC Ex. : Solenoid Valves, lamps, Actuators, dampers, Pump valve onoff control Power Supply-The power supply gives the voltage required for electronics module (I/O Logic signals, CPU, memory unit and peripheral devices) of the PLC from the line supply. Bus system-IT IS path for the transmission of the signal . Bu system is responsible for the signal exchange between processor and I/O modules
DCS( distributed Control System) Multiple microcomputers connected together to share and distribute the process control workload Features: Multiple process control stations to control individual loops and devices Central control room where supervisory control is accomplished Local operator stations for redundancy Communications network (data highway)
Can be installed in a very basic configuration, then expanded and enhanced as needed in the future Multiple computers facilitate parallel multitasking Redundancy due to multiple computers Control cabling is reduced compared to central controller configuration