Theoretically, there are as many processes as there are products being manufactured in industry today. Although it is understood that no two application is identical, it is important to understand that the control principles that apply to the different industrial applications are basically the same.
DESCRIPTION OF A PROCESS:
A process can be described as a sequence of changes of a substance or matter during production. The sequence of changes may occur in either the physical or the chemical composition and include parameters such as Temperature, Flow, Level, Pressure and Quality. And it always involveS ” CONVERSION “.
Examples of a Process:
1. Mixing of fluids
2. Heating or Cooling of a substances
3. Pumping out of water from source
4. Canning food
5. Deriving gasoline from crude
6. Cement manufacturing
7. And many more..
Base on a figure above, a process could be describe briefly as what is happening…
1. Inside the Distillation column
2. Inside the Furnace
3. Inside the Pipe
TYPES OF PROCESS:
1. Batch Process – it can be describe as production of a product by lot, volume or batch.
There are several advantages of batch production;
a. it can reduce initial capital outlay because a single production line can be used to produce several products.
b. batch production is also useful for a factory that makes seasonal items product, for which it is difficult to forecast demand, a trial run for a production
Batch production also has disadvantage;
a. there are inefficiencies associated with batch production as equipment must be stopped, reconfigured, and its output tested before the next batch can be produced.
2. Continuous Process – is a method used to manufacture, produce or process materials without interruption. This process is followed in most oil and gas industries and petrochemical plants.
The most important difference between batch and continuous production is that in continuous, the chemical transformations of the input materials are made in continuous reactions that occur in flowing streams of the materials whereas in batch they are done in volume/containers.
Difference between System and Process:
System – Refers to the interconnection of equipment, piping or any mechanized structure used in any manufacturing process.
Process – could be described as what is occurring/ happening within a system.
Process Dynamics
Process Dynamics is otherwise known as the personality or behavior of a process. Most processes contain resistance (R), capacitance (C) and dead time elements, which will determine their dynamics and steady state response to upsets.
Knowing the personality of the process enables the control designer to accurately match the type of control strategy to be used for the desired control. Therefore it is absolutely necessary to identify these personalities.
Resistance Capacitance – Time Element
A more common type of time lag takes the form of R-C time constant which made up of two components: Resistance and Capacitance.
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Roldan B. Sebastian 