Process Control

PROCESS CONTROL

Prepared by: Dave Danque

WHAT IS PROCESS CONTROL?

Many different operations are performed in an industrial machine to manufacture a product. Each one of these operations is referred to as process.

Process control is the automatic operations performed by an industrial manufacturing machine.


EXAMPLES OF INDUSTRIAL MANUFACTURING MACHINES

Metal Cutting Machine Prepared by: Dave Danque

Metal Forming Machine Prepared by: Dave Danque

PROCESS MEASUREMENT AND CONTROL

Raw materials are manipulated through various processes to manufacture goods and provide public services.

These products and services are provided by either in BATCH PROCESSES or by CONTINUOUS PROCESSES.


I. CATEGORIES OF CONTROL

Prepared by: Dave Danque and Jane – Josanin Elizan

A. BATCH PROCESSES• Products are made one batch at a time.


NEWSPAPER

BREAD

A. BATCH PROCESSES

• Usually in smaller quantities than the products produced by the continuous method.

• A sequence of steps is performed.

• Products are made by putting ingredients into a vessel, called a reactor, and then causing them to react to form a product.


A. BATCH PROCESSES

Prepared by: Dave DanqueBATCH REACTOR

A. BATCH PROCESSES

• The type of material used to construct the reactor depends on factors such as:

(1)its capability to withstand the corrosiveness of the ingredients inside, and

(2) its capability not to contaminate the contents inside.


1. CONTROL REQUIREMENTS

a) Controlling the Quantity of Raw Materials

• Determining the weight of the ingredients inside the reactor with a pressure sensor.

• Using a level sensor to read the height of the ingredients in the vessel.

Prepared by: Jane – Josanin Elizan


• Calculating the volumetric flow rate of a raw material being fed into the reactor by using a flowmeter.


b) Controlling the Process Variables During the Reaction Cycle

• The two most common variables that must be regulated to control the rate of reaction are the temperature and pressure.

• Applying thermal energy and maintaining the temperature at a certain level is critical to most batch processes.


ENDOTHERMIC PROCESSES


EVAPORATING LIQUID WATER

BAKING BREAD

EXOTHERMIC PROCESS


COMBUSTION OF FUELS LIKE COAL

SETTING OF CEMENT & CONCRETE

•Most batch reactors use a thermal jacket and circulation coils

Prepared by: Jane – Josanin ElizanBATCH REACTOR

c) Controlling Each Step in the Sequence

Feeding (Feeders) Mixing (Mixing Plant with Tandem Vessel)


Heating Cooling (Infrared Convection Oven) (Fluid Bed Dryer)


Reacting Discharging


Cleaning


TYPES OF BATCH PROCESSES

Prepared by: Sheena Guiking

2. TYPES OF BATCH PROCESSES

A. Mixing/Blending involves combining two or more ingredients together and may only require a one-step process.

• Example : Mixing paint


B. Chemical Reaction involves combining two or more materials or reactants to form a product. The reaction usually occurs under the influence of temperature, pressure and agitation and by introducing a catalyst.

• Example : Fertilizers


C. Separation refers to the removal of an ingredient from the mixture. Another type of separation process is crystallization, which is the formation of a solid material from a solution, vapor, melted material, or solid that is in a different phase of the reaction.

• Example : Pharmaceuticals


D. Polymerization involves the combination of a large number of molecules to form a new product.

• Example : Plastics, synthetic materials


B. CONTINUOUS PROCESS

Prepared by: Lara Litusquen

• Raw materials are continuously passed through manufacturing equipment at a controlled rate, and the end product is continuously withdrawn.

• Designed to manufacture a large volume of a particular product.


• Examples of this:

PETROLEUMCHEMICALS


CONTINUOUS PROCESS

MANUFACTURING EQUIPMENTS

Prepared by: Lara Litusquen and Stephen John Trinidad

SCREENS AND ROLLERS ON A PAPER

MACHINE

EXTRUDERS THAT SHAPE PLASTIC

BAGSPrepared by: Lara Litusquen

EVAPORATOR THAT PROCESSES LIQUIDS Prepared by: Lara Litusquen

1. CONTROL REQUIREMENTS

A. Controlling the Quantity of Raw Materials

• Materials can be: (1) granules, (2) powder,(3) pulp, (4) sewage, (5) water, and/or (6) petroleum.


• The quantities of these materials are measured primarily by various types of flow sensors. Flow valves are used to vary the rate at which the raw materials are fed into the process.

FLOW VALVES


b. Controlling Operating Parameters During the Process

i. Temperature – heating and cooling

ii. Pressure – to raise the boiling temperature and to shorten the reaction time

iii. Level – to determine the amount of material that is inside the vessel

Prepared by: Stephen John Trinidad

iv. Flow – to maintain temperature and to regulate pressure level

V. Product CompositionComposition – conditions of the product solution

often affected by temperature, flow, level, and pressure

Analyzer – a sensor used to measure status

Analytical Control – controlling the composition of the product

Prepared by: Stephen John Trinidad

II. CLASSIFICATIONS

OF CONTROL

Prepared by: Lailani Marie Delos Santos and Zyrill Mae Aguirre

• This process requires an addition of a feedback loop making it self-regulating. Its primary element is a sensor. The sensor’s output is the measured variable. The controller then compares feedback signal to the set point. An error signal determines which type of control signal to produce at its output. The control signal is the one being sent to the final control element. The manipulated variable, however, causes a change in the controlled variable.

Prepared by: Zyrill Mae Aguirre

2. CLASSIFICATION OF CONTROL

A. OPEN-LOOP CONTROL

Prepared by: Lailani Marie Delos Santos

• This process is controlled only by setpoint commands, without feedback measurement signals.


• Examples :

CAFETERIA DISHWASHERS

LAUNDRY MACHINES


• As an advantage, it is relatively inexpensive. But it has no control capabilities to make corrections if the process deviates from its required state.


B. CLOSED-LOOP CONTROL


CLOSED – LOOP TEMPERATURE PROCESS


PROCESS BEHAVIOR

• Variable – an element varies when an influence to which it is exposed causes change.

• Change can happen when :- a disturbance appears -load demands vary - setpoints are adjusted

• Step change – takes place over a small time interval


ADVANCED CONTROL TECHNIQUES

Prepared by: Reofe Ellinore Flores

C. ADVANCED CONTROL TECHNIQUES

1. CASCADE CONTROL – designed to respond to changes in the controlled variable

2. FEED-FORWARD CONTROL – process must deviate from setpoint before control action is applied


3. RATIO CONTROL – proportionally control the flow of one ingredient based on the amount of flow of another ingredient.

4. ADAPTIVE CONTROL –accommodates non-linear processes


FEEDBACK SYSTEM VERSUS FEED-FORWARD CONTROL

• A feedback system determines a correction that needs to be made after the controlled variable deviates from set point. While a feed-forward control is used when no variation from setpoint can be tolerated in a process or when a system is very slow in responding to corrective action.


Documents

Process Control