B.ENG (HONS) IN CHEMICAL ENGINEERING
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inclusion of the course in
Total Student Learning
First-Order System: Transient Response of a
Thermocouple to a Step Temperature Change
Last Modified 9/6/06
Many mechanical, thermal, and electrical systems can be modeled using first-order
differential equations. In this experiment we will
FUNDAMENTAL THERMOCOUPLE LAWS
Figure 1: Typical thermocouple measuring circuit.
The basic thermocouple circuit as shown in Figure 1 can be used to measure the difference
between the two temperatures T1 and T2 which is temperature at junction 1 and junctio
.Also called inferential type flow meters
.They do not measure the flow directly, but instead measure another physical quantity which is related to the flow
.Variable area meters
.Variable head meters
.Variable head and variable area
Non electrical method
Electrical methods are in general preferred for the
measurement of temperature as they furnish a signal which
can be easily detected, amplified or used for control
Describe about deflection type and null type instruments with the help of an
example (one example for each type).
-Physical effect generated by measuring quantity produce a displacement/
deflection in instrument (1 mark)
Comparison between static and dynamics characteristics
The performance criteria for the measurement
of quantities that remain constant, or vary only
refer to the comparison between steady
output and ideal output when
Process Instrumentation & Instrumental Analysis
Process & Instrumentation Diagram
Process & Instrumentation Diagram (P&ID)
It represents a document that can take on many different forms
depending upon the following factors:
1. Nature of the pro
No Date Class Rev
Production of Cumene
Drawn: Group X
Design: Group X
Produced as a pure compound Converted to cumene hydroperoxide
Intermmediate in the synthesis of primarily phenol and acetone.
The reactions for cumene production from benzene and propylene are as follows:
STANDARD & CALIBRATION
? Measurement is an act of a quantitative comparison
between a predefined standard and unknown
magnitude of a physical quantity
? Requirement of measurement:
? 1) The standard that is used for comparison must
Acetone (2-propanone) (CH3)2CO.) is the simplest and most important aliphatic
ketone. As a solvent, it is mainly used in the paint and lacquer industry. In synthetic
work acetone is used for the production of important chemicals such as m
2. Application Of Instruments
3. Functional Element
4. Classification of instruments
5. Microprocessor- based instrumentation
6. Standard & calibration
Instrument rarely respond instantaneously to
changes in the measured variables
Instead, they exhibit a characteristic
slowness/sluggishness due to mass, thermal
capacitance, fluid capacitance or electri
Measurement Of Temperature
Non- Electrical Methods
Temperature is a very widely measured and
frequently controlled variable used in
Measures temperature by detecting thermal radiation from an
object without touching the object.
Consists of an optic system which accumulates visible infrared
energy and focuses the energy to the detector.
The detector will c
.you drive your car with
your eyes shut?
IMPORTANCE OF PROCESS CONTROL
ENVIRONMENTAL & EQUIPMENT PROTECTION
REDUCE ENERGY CONSUMPTION
MONITORING & DIAGNOSIS
Why we need to control a proces
.Electrical methods are in general preferred for the measurement of temperature as they furnish a signal which can be easily detected, amplified or used for control purposes.
.There are two main electrical methods used for measuring te
The principle behind a bimetallic strip thermometer relies on the fact that different metals expand at different rates as they warm up.
An increase in T causes the deflection of the free end of the strip- assuming that metal A has
THERMAL MASS FLOW METER
.Mainly for gas flow
.The thermal mass flow meter operates independent of density, pressure, and viscosity.
.Thermal meters use a heated sensing element isolated from the fluid flow path where the flow stream conducts heat from the
.This is used between 0.01 and 1000 micronsc(modified mercury manometer)
.PRINCIPLE: compressing a known volume of low- pressure gas to a higher pressure and measuring the resulting volume change.
.Simple to use, the calibration is same for n
.A manometers is the simplest device for measuring static pressure.
.A simple U-tube manometer uses water, mercury or ant other suitable fluid
.The difference in levels h between the two limb is an indication of the pressure difference (p2 -p1
The performance of flow meters is also influenced by a dimensionless unit called the
Reynolds Number. It is defined as the ratio of the liquid's inertial forces to its drag (viscous) forces.
The Reynolds number is used for determinING whet
? The ratio of the magnitude of response (output signal) to
the magnitude of the quantity being measured (input
? Also termed as scale factor /gain of the instrument
? Determined from result of static calibration
Performance characteristic indicates the capabilities
& limitations of the instrument for particular
It is important as it enables us to have quantitative
estimate of pros/cons of instrument
So, we can select the opt
This method infer level by measuring the hydrostatic head produced by the liquid column.
A pressure sensing element is installed at the bottom of the tank and pressure is converted to level.
Different liquid densiti
BASIC FUNCTIONAL ELEMENT
.Element that sense & convert the desired input to a more convenient and practicable form to be handle by the measurement systems
-SIGNAL CONDITIONING /intermediate modifying
.For manipulating /processing the
A thermocouple having a sensitivity of 4.8 mV/oC has been
used for the measurement of temperature.
Its output is connected to a moving coil millivoltmeter which
has a sensitivity of 1o/mV.
The length of the
Describe about accuracy and precision.
Accuracy (5 marks)
-The closeness of the instrument output to the true value of the measured
quantity (as per standard)
-It is specified as the percentage of deviation or inaccuracy of the measurement