automated process control system

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By: v.ramani007 (1 month(s) ago)

Excellent presentation Mem, Can you plz send me a copy of this ppt at v.ramani007@gmail.com

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Dear Mrs Chetana I would be very grateful if you could allow us to download this presentation by sending it by a link best regards yours Salih salihobeid@gmail.com

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Automated process control system:

Automated process control system By Mrs. Chetana D. Modi

Automated process control system:

Automated process control system Automatic control systems enable us to operate our processes in a safe and profitable manner. Consider, processes with streams comprised of gases, liquids, powders, slurries and melts. Control systems achieve this "safe and profitable" objective by continually measuring process variables such as temperature, pressure, vacuum, flow and concentration - and taking actions such as opening valves, slowing down pumps and turning up heaters - all so that the measured process variables are maintained at operator specified set point values.

Advantages :

Advantages Good quality at low cost Save material Safety to personnel, plant, processes Cost accounting Increase yield Reduced labor cost

Basic elements of process control system:

Basic elements of process control system

Elements of process control system:

Elements of process control system To sense the value of process variable To transmit the signal to measuring element To measure the process variable & convert of movement To present the value of measured variable To set the desired variable value Compare measured and desired set point value Transmit control signal to final control element To control manipulated value

Temperature measurements:

Temperature measurements Temperature is the degree of hotness or coldness measured on a definite scale. It is the intensity factor for heat. It have significant effect in the process of sterilization and drying of the granules. Temperature can be mesured in 0 C, 0 F, 0 K, 0 R.

Temperature measuring elements based on physical principles:

Temperature measuring elements based on physical principles Sr.No . Physical principles Instruments Approx temp. range 0 C 1 Volumetric expansion or contraction of fluids Liquid –in-glass thermometers Pressure-spring thermometers Liquid filled (mercury) Gas filled Vapour pressure Other liquids 100-550 40-550 125-450 50-350 200-300

Temperature measuring elements based on physical principles:

Temperature measuring elements based on physical principles Sr.No . Physical principles Instruments Approx temp. range 0 C 2 Differential expansion of dissimilar metals Bimetalic thermometers- thermostates , thermocouple pyrometer 40-500

Temperature measuring elements based on physical principles:

Temperature measuring elements based on physical principles Sr.No . Physical principles Instruments Approx temp. range 0 C 3 Generation of thermoelectric emf in circuit comprising two dissimilar metals Copper constantan thermocouple Iron constantan thermocouple, J & Y type Chromel-alumel thermocouples Platinum-platinum rhodium thermocouples (noble metal couples) 200-300 30-350 30-1100 30-1550

Temperature measuring elements based on physical principles:

Temperature measuring elements based on physical principles Sr.No . Physical principles Instruments Approx temp. range 0 C 4 5 Change of electrical resistance Monochromatic radiation from hot body Resistance thermometer (metal wire) Copper nickel Platinum Optical pyrometer 100-125 100-325 240-1000 600 and up

Temperature measuring elements based on physical principles:

Temperature measuring elements based on physical principles Sr.No . Physical principles Instruments Approx temp. range 0 C 6 7 Total radiation from hot body Fusion of solids Radiation pyrometer Therompiles Seger cones ( Pyrometeric cones) 400 and up 1100-3700

Liquid-in-glass thermometer:

Liquid-in-glass thermometer

Mercury filled pressure-spring type thermometer:

Mercury filled pressure-spring type thermometer

Bimetallic thermometer:

Bimetallic thermometer

Thermocouple pyrometer:

Thermocouple pyrometer

Resistance thermometer:

Resistance thermometer

Optical pyrometer:

Optical pyrometer

Thermopiles :

Thermopiles

Radiation pyrometers:

Radiation pyrometers

Pressure-vacuum measurements:

Pressure-vacuum measurements Pressure means force exerted against a given surface area. It is both force and area measurement. Difference between the pressure of a confined fluid and that of atmosphere is known as gauge pressure . Gauge pressure + atmospheric pressure=absolute pressure. Pressure below atmospheric pressure=vacuum. Units of pressure PSI KG/CM 2 Height of a liquid in column Feet water, mm.Hg

Classification of pressure-vacuum measuring methods:

Classification of pressure-vacuum measuring methods Sr.No . Physical principles Instruments Approx range 1 Rise or fall of liquid in manometer ( Liquid-column liquid ) U-tube manometer McLeod gauge Absolute pressure gauge Fixed cistern barometer Bell type element Ring-balance manometer 1 mm to 10 cm.Hg 10 to 1.0 mm Hg.

Liquid column method:

Liquid column method Hydrostatic pressure exerted by a liquid at the lower end of a column is directly proportional to the height of liquid in the column.

U-tube manometer:

U-tube manometer Hydrostatic pressure exerted by liquid=height of liquid in the column

McLeod gauge:

McLeod gauge

Absolute pressure gauge:

Absolute pressure gauge

Fixed cistern barometer:

Fixed cistern barometer

Bell type liquid column pressure gauge:

Bell type liquid column pressure gauge

Ring balance manometer:

Ring balance manometer

Classification of pressure-vacuum measuring methods:

Classification of pressure-vacuum measuring methods Sr.No . Physical principles Instruments Approx range 2 Deformation of a shaped metal form (Elastic-element method) Bourdon tube gauges Helix gauges Spiral gauges Diaphragm gauges Bellows gauge 5 to 100,000 psig 7 to 80000 psig 30 to 4000 psig 20 oz to 10 psig 10 to 760 mm Hg

Deformation of shaped metal form :

D eformation of shaped metal form Measured pressure deform (Hooke’s Law) some elastic material (metallic) within its elastic limit, the magnitude of deformation being approximately proportional to the applied pressure.

Bourdon spring pressure gauge:

Bourdon spring pressure gauge Measured pressure deforms some elastic material

Helix gauge:

Helix gauge Spiral gauge

Diaphragm gauges:

Diaphragm gauges

Bellow gauges:

Bellow gauges Spring opposed bellows Dual spring and bellows

Classification of pressure-vacuum measuring methods:

Classification of pressure-vacuum measuring methods Sr.No . Physical principles Instruments Approx range 3 Conversion of pressure into mechanical displacement which is measurable by an electric strain gauge. Strain gauge Piezoresistive transdeucers Piezoelectric transducers Force-balance ( ocillator ) Magnetic Capacitance pressure transducer 0 to 50000 psig

Electrical methods:

E lectrical methods Measuring element converts an input pressure to an electrical output signal proportional to pressure.

Piezoelectric transdrucers:

Piezoelectric transdrucers

Classification of pressure-vacuum measuring methods:

Classification of pressure-vacuum measuring methods Sr.No . Physical principles Instruments Approx range 4 Heat loss from a hot filament surrounded by gas Thermal gauge Pirani gauge Thermocouple gauge 10 -3 to 1 mm Hg 10 -3 to 0.5 mm Hg

Heat loss from a hot filament surrounded by gas :

Heat loss from a hot filament surrounded by gas Energy dissipated from a heated surface has a temperature proportional to the pressure of the surrounding gas.

Classification of pressure-vacuum measuring methods:

Classification of pressure-vacuum measuring methods Sr.No . Physical principles Instruments Approx range 5 Ionic current produced by electrodes which bombard molecules of residual gas Ionization gauges Hot cathode ion gauge Alphatron gauge ( α -particles) 10 -6 to 10 -3 mm Hg 10 -3 to 10 mm Hg

Ionization vacuum gauges:

I onization vacuum gauges When gas molecules collide with electrons, ions are formed this formation of ions varies linearly with the gas pressure at pressure below 10 -3 mm of mercury.