The document provides an overview of a petrochemical complex located in northern India. It consists of several key units: (1) a gas processing unit to recover ethane and propane from natural gas, (2) a gas cracker unit to produce ethylene and propylene, and (3) downstream polyethylene production units. Safety procedures at the plant include wearing protective equipment, locating assembly points, and pushing emergency buttons. Temperature and pressure sensors are discussed, along with calibration devices. The document concludes with descriptions of programmable logic controllers and distributed control systems used to remotely monitor and control industrial processes.

1. 1
Overview of the plant
GAIL (India) limited, is operating successfully an integrated gas based Petrochemical complex
at Pata (U.P) since March 1999. The petrochemical complex is the only petrochemical plant
located in north-central India. This complex recovers ethane-propane (C2/C3) from natural gas,
after sweetening, (CO2 removal), coming from Pipeline for producing Petrochemicals. The
ethane-propane mixture recovered from Gas processing unit is cracked in Gas Cracker Unit to
produce ethylene and propylene. After cracking, it is sent to downstream plants for
polymerization, which is then sent for bagging in the form of pallets. Ethylene is converted to
final products — HDPE (High Density Poly Ethylene) and LLDPE (Linear Low Density
Polyethylene). Polyethylene is manufactured under both the G-Lex and G-Lene trade names in
numerous grades, including injection moldings, blow moldings, raffia, monofilament, pipe and
film. The Pata Petrochemical Complex consists of following units:
a) GPU (gas processing unit)
b) GCU (gas cracker unit)
c) LPG Recovery unit
d) HDPE unit
e) LLDPE unit
Figure no.1

2. 2
FIRE AND SAFETY
Primary safety measure that we should take is never put your safety helmet off in the field
and wear safety shoes every time.
Some fire and safety guidelines:
1. In case of emergency first thing to undertake is observe the windsock which gives the
direction of the wind always run opposite to it.
2. At crisis locate the (assembly point) because they are the safest location in the plant.
3. At case if chemical falls on you immediately rush to safety showers which are
located in each unit of the plant.
4. At the time of crisis if you see fire at any point of the plant push the emergency cell
button which are present outside every
Unit.
Figure no.2

3. 3
Introduction to Sensing and Measuring devices
Temperature sensing devices
Some of the more common instruments used
 Thermocouples
 Resistance thermometers (RTDs)
Thermocouple:
A thermocouple is a sensor that measures temperature. It consists of two different types of
metals joined together at one end. When the junction of the two metals is heated or cooled,
a voltage is created that can be correlated back to the temperature.
Figure no.3
Working principle of thermocouple:
The thermocouple working principle is based on the Seeback Effect. This effect states that
when a closed circuit is formed by jointing two dissimilar metals at two junctions, and junctions
are maintained at different temperatures then an electromotive force (e.m.f.) is induced in this
closed circuit.

4. 4
 Types of thermocouple , range and material:
Figure no.4
Resistance temperature detector (RTDs):
An RTD (Resistance Temperature Detector) is a sensor whose resistance changes as its
temperature changes. The resistance increases as the temperature of the sensor
increases. The resistance vs temperature relationship is well known and is repeatable
over time. An RTD is a passive device.
Figure no.5

5. 5
PT100:
The RTD PT100, which is the most commonly used RTD sensor, is made of platinum (PT),
and its resistance value at 0°C is 100 O. In contrast, a PT1000 sensor, also made of platinum,
has a resistance value of 1000 O at 0°C.
Working principle of RTD:
Resistance Temperature Detectors (RTD) operates on the principle that the electrical
resistance of a metal changes predictably in an essentially linear and repeatable manner with
changes in temperature. RTD have a positive temperature coefficient (resistance increases
with temperature). also Pt500 or Pt1000 RTD sensors are used.
Figure no.6
Temperature range of PT100:
Platinum resistance thermometers (PRTs) offer excellent accuracy over a wide temperature
range (from –200 to +850 °C).
Temperature transmitter:
A temperature transmitter is an electronic device used to send a temperature measurement over
two wires to the processing unit. The transmitter is responsible for converting the small
electrical signal from the temperature sensor into a more readable signal for the processing
unit.

6. 6
Figure no.7
 Pressure sensing devices:
 Bourdon tube pressure gauge
 Diaphragm pressure gauge
 Capillary pressure gauge
Bourdon tube pressure gauge:
A bourdon tube pressure gauge is a mechanical pressure measuring instrument that reads
the pressure without requiring any electrical power. It is generally used for the
measurement of pressure from 0.6 to 7000 bar (8 to 10000 psi).
Figure no.8

7. 7
Diaphragm pressure gauge:
Diaphragm pressure gauges are preferably used for low pressure ranges. Through the large
working surface of the circular, corrugated diaphragm element, small pressure ranges can be
measured reliably.
Figure no.9
Pressure unit: The pressure measure unit for the diaphragm pressure gauge is bar or psi. The
pressure may usually range from -1 to 400 bar.
Capillary pressure gauge
Capillaries are used for mounting pressure gauges, transmitters, and switches away from
the tank or pipe. This may be done for several reasons. You might wish to mount your
pressure instrument in an area with good visibility, like an instrument panel. In other cases,
it may be necessary to reduce instrument pulsation.
Figure no.10

8. 8
 Calibration
Calibration is the process of configuring an instrument to provide a result for a sample
within an acceptable range. Eliminating or minimizing factors that cause inaccurate
measurements is a fundamental aspect of instrumentation design.
 Deadweight tester:
A deadweight tester is a calibration standard that uses the principle of a pressure balance to
calibrate pressure measuring instruments. Deadweight testers use calibrated weights to
apply known pressures to a device under test for a simple and cost-effective solution that
covers a wide range of pressure calibrations.
Figure no.11
Pressure transmitter:
A pressure transmitter is a mechanical device that measures the expansive force of a liquid or
gaseous sample. Also known as a pressure transducer, this type of sensor is typically composed
of a pressure sensitive surface area made of steel, silicon, or other materials depending upon
the analyte's composition.

9. 9
Figure no.12
 Flow sensing devices
 Rotameter
 Mass-flow meter
 Orifice plate
Rotameter:
A rotameter is a device that measures the volumetric flow rate of fluid in a closed tube. It
belongs to a class of meters called variable-area flowmeters, which measure flow rate by
allowing the cross-sectional area the fluid travels through to vary, causing a measurable
effect.
Figure no.13

10. 10
Mass-flow meter:
A mass flow meter, also known as an inertial flow meter, is a device that measures mass
flow rate of a fluid traveling through a tube. The mass flow rate is the mass of the fluid
traveling past a fixed point per unit time.The mass flow meter does not measure the volume
per unit time (e.g. cubic meters per second) passing through the device; it measures the
mass per unit time (e.g. kilograms per second) flowing through the device. Volumetric flow
rate is the mass flow rate divided by the fluid density. If the density is constant, then the
relationship is simple.
Figure no.14
Orifice plate:
An orifice plate is a circular plate inserted into a pipe that has a hole for the flow to pass
through. The hole is smaller in diameter than the pipe, creating flow restriction and pressure
drop.
Figure no.15 (Orifice plate with flow meter)

11. 11
Level sensing devices
 Glass-tube
 Float type
Glass-tube:
Use of a sight glass is probably the simplest method of measuring liquid level. The sight glass
is attached to the outside of the tank so that the liquid level can be seen through the glass. The
sight glass is marked with graduations to allow the level to be measured.
Figure no.16
Float-type:
One common form of level measuring system uses a tape or servo motor which is connected
to a float. The height can be read as the float moves with liquid level. Float devices use the
buoyancy of a float to indicate the liquid level in the tank. One common approach is to
attach the float to a chain.
Figure no.17

12. 12
Level transmitters:
 Radar
 DP type
Radar:
Radar level instruments measure the distance from the transmitter (located at some high
point) to the surface of a process material located farther below in much the same way as
ultrasonic transmitters – by measuring the time-of-flight of a traveling wave.
Figure no.18
DP type:
The differential pressure flow meter measures the volume flow in gases, liquids and steam.
They are particularly used in situations where high pressure, high temperature or a large
diameter play a role. They are mainly found in the chemical, oil, gas and power industries.
Figure no.19

13. 13
DISTRIBUTED CONTROL SYSTEM AND PROGRAMMABLE
LOGIC CONTROLLER
Any industrial plant there are many of devices to maintaining and controlling.
we can remotely control the process on DCS/PLC.
PROGRAMMABLE LOGIC CONTROLLER(PLC):
A PROGRAMMABLE LOGIC CONTROLLER (PLC) is an industrial computer control
system that continuously monitors the state of input devices and makes decisions based upon
a custom program to control the state of output devices.
WHAT IS INSIDE A PLC?
The Central Processing Unit, the CPU, contains an internal program that tells the PLC how to
perform the following functions:
 Execute the Control Instructions contained in the User's Programs. This program is
stored in "nonvolatile" memory, meaning that the program will not be lost if power is
removed
 Communicate with other devices, which can include I/O Devices, Programming
Devices, Networks, and even other PLCs.
 A PLC will consist of two basic sections: the central processing unit (CPU) and
the Input/Output (I/O) interface system.
Significance of programmable logic controller:
A PLC (programmable logic controller) is a digital computer used for industrial automation to
automate different electro-mechanical processes. It was introduced to eliminate issues such as
high power consumption that arose from the use of relays to control manufacturing processes.
and its response is very short.

14. 14
DISTRIBUTED CONTROL SYSTEM (DCS):
A distributed control system (DCS) is a digital automated industrial control system (ICS) that
uses geographically distributed control loops throughout a factory, machine or control area.
Figure no.20
Significance of distributed control system:
Distributed control systems are particularly necessary in very large manufacturing operations
where thousands of control loops need to be monitored in real-time. Human engineers cannot
manually monitor these many individual systems, which is why an automated central system
is required. The DCS enables applications such as production scheduling, preventative
maintenance scheduling, and information exchange.
A DCS facilitates the geographical distribution of subsystems throughout your plant. Used
correctly, a DCS can greatly monitor or improve operational features such as:
 Efficiency
 Risk of subsystem failure (and isolate a failed subsystem for maintenance)
 Reporting
 Safety
 Security

15. 15
 HART (Highway Addressable Remote Transducer):
HART communicator enabled process calibration tools are designed to help you get the most
out of your smart transmitter calibrations. The HART protocol is an industry standard used
globally to send and receive information between smart devices and control systems and is the
most popular digital communication standard in the field today. Allowing simultaneously use
analog and digital 4-20 mA signals over the same wiring Fluke has a HART enabled process
tool to meet your needs—whether you’re troubleshooting control systems, calibrating
instrumentation or verifying asset health.
Figure no.21
 Calibrate a temperature transmitter with HART communicator:
Calibrating a HART temperature transmitter requires an accurate temperature simulator or
temperature source, mA measurement, and a HART communication tool for calibration.
You can use separate tools or a calibrator that integrates all three to perform this task.
HART is an industry standard defining the communications protocol between smart field
devices and a control system that uses 4-20 mA wiring.

16. 16
Valves
A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases,
liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various
passageways.
Significance of the control valve:
A control valve is a valve used to control fluid flow by varying the size of the flow passage as
directed by a signal from a controller. This enables the direct control of flow rate and the
consequential control of process quantities such as pressure, temperature, and liquid level.
Figure no.22
Types of control valves:
Control valves are available in different types and shapes.
They can be classified in different ways; based on:
(a) Action
(b) Number of plugs, and

17. 17
(c) Flow characteristics.
(a) Types of Control Valves based on Action:
Control valves operated through pneumatic actuators can be either
(i) Air to open.
(ii) Air to close.
They are designed such that if the air supply fails, the control valve will be either fully open,
or fully closed, depending upon the safety requirement of the process.
For example, if the valve is used to control steam or fuel flow, the valve should be shut off
completely in case of air failure. On the other hand, if the valve is handling cooling water to a
reactor, the flow should be maximum in case of emergency.
The schematic arrangements of these two actions are shown in Fig. Valve A are air to close
type, indicating, if the air fails, the valve will be fully open. Opposite is the case for valve B.

18. 18
Figure no.23
(b) Types of Control Valves based on Number of plugs:
Control valves can also be characterized in terms of the number of plugs
present, as
(i) Single-seated valve
(ii) Double-seated valve
The advantage of this type of valve is that, it can be fully closed and flow variation from 0 to
100% can be achieved. But looking at its construction, due to the pressure drop across the
orifice a large upward force is present in the orifice area, and as a result, the force required to
move the valve against this upward thrust is also large.
Thus this type of valves is more suitable for small flow rates. On the other hand, there are two
plugs in a double-seated valve; flow moves upward in one orifice area, and downward in the
other orifice.
The resultant upward or downward thrust is almost zero. As a result, the force required to move
a double-seated valve is comparatively much less.

19. 19
Figure no.24
(c)Types of Control Valves based on Characteristic of control valve:
All control valves have an inherent flow characteristic that defines the relationship between
‘valve opening’ and flowrate under constant pressure conditions. Please note that ‘valve
opening’ in this context refers to the relative position of the valve plug to its closed position
against the valve seat. It does not refer to the orifice pass area. The orifice pass area is
sometimes called the ‘valve throat’ and is the narrowest point between the valve plug and seat
through which the fluid passes at any time. For any valve, however it is characterized, the
relationship between flowrate and orifice pass area is always directly proportional.

20. 20
REFERENCE
https://instrumentationtools.com/basics-control-valves/
https://gailonline.com/
https://instrumentationtools.com/category/basics/
Electronic Measurements and Instrumentation
Book by K. Lal Kishor