Instrumentation….Instrumentation systems………process instrumentation…Instrumentation and control…automation and control
What are they?
Suppose you are in a industry. Say in a refinery. What is happening in such industries .???
Making some products,modifying, refining etc ….right?….
How they do this ?
Yes. They do some process.
Treatment,storing, packaging,regulating, Reactions… ..etc …etc.. right?
we call them as process .
Take an example of of petroleum refinery.crude oil is refined to various products such as LPG,petrol, kerosene , diesel etc. How they do this?They process the crude oil in a certain predefined way and make the products. Some of the examples of such process in this refinery is
Distillation ,Cracking , catalytic reforming , alkylation etc.
All these functions are meant for getting a required output or results in their various stages. We call these overall events as process.
The process have to be carried in a required way. Means some of the parameters have to be maintained within the required values . Functions and events of this process must be go through the desired way .So we will get the required results or products.
Let’s go through some of these
* keeping the temperature of a process liquor within the specified limit.
* Adding a reactant to a tank when required.
* Keeping a agitator running for a required time
* maintaining flow through a pipeline within the required setpoint.
* Shut down a plant at emergency condition
* Turning a Electric heater On / Off to maintain the temperature of a liquor in a vessel.
* Initiating alarms when required .
All above are examples of the steps and procedures of a process.
So doing jobs like this.what we need?
We need to measure the values of process variables .we should be aware how the process has to carrie out .
We should know
. What are the values of process variables
When to open this valve?
And how much opening or closing need?
What is the pressure in tank?
What is the temperature?
What is the flow rate of the liquor passing.
Is the level in tank high? or low?
Is the motor running or not?
Is the valve open or close?
Etc etc
We need to know data like this.
So we measure the required parameters , We collect various status of machineries like pumps, motors ,valves, agitators etc .These are done with the help of proper instruments .
Monitor
The measured values should be monitored so that an operator can examine .So monitoring and recording devices are a main part .
Control
Control means taking necessary actions on the process to bring it in a required way .
Ex: Turning a heater on /off as per the temperature setpoint.
Controlling level in a tank by opening or closing a valve
Maintaining the process parameters at the desired values .
Instrumentation and control
instrumentation is the process of , measuring, recording, monitoring,controlling and analyzing physical quantities using various types of process control elements such as sensors,final control elements , control systems etc .
Process parameters or process variables in any industrial environment can be monitored and controlled in a required manner by establishing properly designed instrumentation systems . They may different from each other from industries to industry.For example instrumentation systems which are used in a petroleum refinery differes from that used in food packaging industries .
Measure ,control ,monitor .... what?
The physical parameters that has to be controlled and monitored are commonly known as process variables . examples of such variables in a process industry like chemical or petrochemical plants are,
Pressure,Flow rate, Level , Temperature ,Density,Turbidity , etc .
In bottling plants or packaging industries the parameters may differ from above as the process is different and also it’s nature.
So nature and design of instrumentation and automation systems differ according to the nature and type of applications in industry
Sensors,Transmitters .
Process variables are measured using proper sensors and devices .And the required variables are transmitted to control station .For example
a magnetic flow meter senses flow rate of liquid
An ultrasonic level Transmitter senses level in a tank.
A pressure gauge reads pressure in a column or vessel or pipeline or whatever it is.
A proximity switch senses presence of an object near to it.
An RTD measures temperature of a medium
.
So you can see various types of sensors transmitters devices switches etc .These are employed for the measuring process variables and process conditions and transmitting them to a control or monitoring stations or devices .
Control systems .
Control systems
Different types and designs of control systems are available in industries
These control systems are capable of receiving process variable input Recording and monitoring them .Taking necessary actions.as per the control philosophy of the process .
.The selection of a particular system is as per our need and nature of process .Some examples of them are
Hard wired relay based control systems ,
electronic controllers ,
,modern control systems like PLC and DCS, SCADA
The measured values of process variables are monitored in control rooms or local stations .And based on these variables necessary action is taken by the control systems .Like valve opening .start/ stop a motor
Open or close a valve
Initiating a alarm
Etc.Hard wired relay based control systems , electronic controllers ,modern control systems like PLC and DCS etc are some examples of control systems
These jobs are carried out through control devices and field output devices like relays , control valves, solenoid coil, etc .
importance of instrumentation
Importance of Instrumentation
In older days of industrialization ,process was so simple and lots of manpower is used for attaining an outcome.There were indeed some primitive forms of measurements. For example level measurements are done with float and rope systems .The product quality was affected because of human errors .Lots of products has been evolved through continuous improvement of science and technology .Also complex and large process emerged . Eventually the need for proper Instrumentation and their development became necessary . It’s development became a part of industrial revolutions . Lots of improvement and technology has been evolved in this area . Today’s instrumentation is so modernized so that we can even monitor and control a process plant from far distance . Without instrumentation we cannot even think about to control a complex process in any type of industry .
So Instrumentation systems plays a major role in an industry
Some of them are given below .
* It helps to increase the quality of the product ..
* Eliminated human errors.
*.Diagonostics and fault finding became easy .
* It reduced the manpower .
* increased safety.
* provided data like history and trending of parameters in a process .
* Increased the Accuracy and reliability of a process .
* It reduced the human efforts.
