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from 1 st June to 30 th June, 2011

Presentation on:-

FUNCTIONING OF CONTROL VALVE THROUGH DCS

Submitted To:

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CONTENTS

INTRODUCTION TO HZL

INTRODUCTION TO CONTROL VALVE

CHARACTERISTICS OF CONTROL VALVE

TYPES OF CONTROL VALVE

MODES OF OPERATION OF CONTROL VALVE

DISTRIBUTED CONTROL SYSTEM (DCS)

PROPORTIONAL INTEGRAL DERIVATIVE CONTROLLER

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INTRODUCTION TO HZL

was incorporated in January1966 as a public sector companyafter the take over of the erstwhileMetal Corporation of India Limited(MCI), to develop mining and smelting

capacities to substantially meet thedomestic demand of zinc and leadmetals.

:

DEBARI CHANDERIA VISHAKHAPATNAM

:

ZAWAR MINES

RAJPURA DARIBA MINES RAMPUR AGUCHA MINES

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INTRODUCTION TO ZINC SMELTER DEBARI

LOCATION : 14km East of Udaipur

PROCESS : Hydrometallurgical

OPERATING CAPACITY : Zinc- 80,000MTSulphuric Acid- 130,000MTCadmium- 250MT

PRODUCTION PERFORMANCE: Zinc Ingots (99.995%)Sulphuric Acid (99.5%)Cadmium (99.5%)

POWER DEMAND : 38-40MW

PRODUCT BUYERS : TATABHEL

STEEL COMPANIES

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VARIOUS DEPARTMENTSPRODUCTION

DEPTT.

SERVICEDEPTT.

ZINC ELECTROLYSIS &MELTING PLANT

ROASTER & ACIDPLANT

LEACHING &

PURIFICATION PLANT

STORES DEPTT.

FINANCE DEPTT.

SALES DEPTT.

SAFETY DEPTT.

ADMINISTRATIONDEPTT.

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INTRODUCTION TO CONTROL VALVE

Valves are used to controlconditions such as flow, pressure,

temperature and liquid level.

Fully or partially opening orclosing in response to signalsreceived recieved from controllers

that compare a "setpoint" to a"process variable" whose value isprovided by sensors that monitorchanges in such conditions.

Opening or closing of valves isdone by means of electrical,hydraulic or pneumatic systems.

Positoners are used to control theopening or closing of the actuator

based on Electric, or Pnuematic Signals.

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CHARACTERSTICS OF CONTROL VALVES

Broadly classified as: MANUAL-

Values are mentioned manually. AUTOMATIC-

Values are regulated through logical programming.

Based on two Signals:ANALOG-

4-20 mAmps.DIGITAL-

start:denoted by 1.

stop:denoted by 0.

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Output is between 0 100% ie..percentage of valve opened.

The range is divided into 4 mAmps for every 25% .

In the field side current is converted into pressure by I to Pconverter according to which valve is opened and closed.

% OPENING CURRENT (mAmps) O/P PRESSURE (bar)

0 4 0.2

25 8 0.4

50 12 0.6

75 16 0.8

100 20 1.0

TABLE

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CONTROL VALVE

BUTTERFLY VALVE THREE WAY VALVE PNEUMATIC VALVE HYDRAULIC VALVE MOTORISED VALVE SOLENOID VALVE

TYPES OF CONTROL VALVE

http://www.iklimnet.com/expert_hvac/hvac_pictures/selonoid_valve.jpghttp://images.google.co.in/imgres?imgurl=http://img.tradeindia.com/fp/0/250/140.jpg&imgrefurl=http://www.tradeindia.com/fp250140/Motorized-Control-Valves.html&usg=__urF-ehIq7ffgAPHuJ3_SQNNFh2k=&h=240&w=240&sz=10&hl=en&start=1&tbnid=krJcr7alcogLMM:&tbnh=110&tbnw=110&prev=/images?q=electrical+Motorised+control+valve&gbv=2&hl=en&sa=Ghttp://www.xomox.de/english/product/accessories/main.h2.jpghttp://images.google.co.in/imgres?imgurl=http://www.swagelok.com/images/cmi/_Valves/Bellows%20Valves/BNcut.jpg&imgrefurl=http://www.swagelok.com/valves/bellows_valves_high_purity_systems.htm&usg=__0gGxDS6YRLPmeWGVMkXAt4pe-tk=&h=332&w=225&sz=7&hl=en&start=8&tbnid=oCDZJdIvWiDwCM:&tbnh=119&tbnw=81&prev=/images?q=pneumatic+valves&gbv=2&hl=en

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PNEUMATIC VALVE :-It operates by a combinationof force created by air

and spring force. A rubber diaphragm separates theactuator housing into two airchambers. The upper chamberreceives supply air. The bottomchamber contains a spring that forces thediaphragm against mechanical stops in theupper chamber.

The position of the valve is controlledby varying supply air pressure in theupper chamber.

As supply air pressure is increasedfrom zero, its force on top of thediaphragm begins to overcome theopposing force of the spring. Thiscauses the diaphragm to move downwardand the control valve to close.

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Pneumaticvalves are

normally usedto controlprocesses

requiring quickand accurateresponse, asthey do notrequire a largeamount ofmotive force.

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HYDRAULIC VALVE :- It consists of a cylinder, piston, spring,

hydraulic supply and return line, and stem.

The piston slides vertically inside thecylinder and separates cylinder into twochambers. The upper chamber contains thespring and the lower chamber containshydraulic oil.

The stem transmits themotion of the piston to a valve.

Initially, with no hydraulic fluid pressure,the spring force holds the valve in theclosed position.

As fluid enters the lower chamber,pressure in the chamber increases.when thehydraulic force due to the pressure isgreater than the spring force, the pistonmoves upward, the spring compresses andthe valve begins to open.

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When a largeamount of force isrequired to operatea valve hydraulicvalves are normallyused.

By regulating theamount of oil

supplied or drained,the valve can beopened betweenfully opened and

closed.

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SOLENOID VALVES :-It consists of a coil, armature,

spring, and stem.The coil is connected to an externalcurrent supply.The spring rests on thearmature to force it downward.

When current flows through the coil,a magnetic field forms around thecoil. The magnetic field attracts thearmature toward the center of thecoil. As the armature moves upward,the spring collapses and the valve

opens.When the circuit is opened andcurrent stops flowing to the coil, themagnetic field collapses. This allowsthe spring to expand and shut the

valve.

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Advantages:-

quick operation

easier to install

Disadvantages:-

They have only twopositions: fully open andfully closed.

They dont producemuch force, so theyusually only operaterelatively small valves.

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Controlling of control valve through loop tuning is called automaticcontrolling. It depends on condition.

For this following parameters are needed to be set:-

SP- Set point The value set by the user for theoperation of valve.

PV- Process variable The value at which the processingtakes place.

OP- Operating value The value at which the valveoperates in the field.

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DISTRIBUTED CONTROL SYSTEM A distributed control system (DCS)refers to a control system usually of a

manufacturing system, process or any kindof dynamic system, in which the controllerelements are not central in location (likethe brain) but are distributed throughoutthe system with each component sub-system controlled by one or morecontrollers.

The entire system of controllers isconnected by networks for

communication and monitoring.

A DCS uses Input & output moduleswhich form component parts of the DCS.The input modules receive informationfrom input instruments in the process andtransmit instructions to the output

instruments in the field.

http://en.wikipedia.org/w/index.php?title=Manufacturing_system&action=edit&redlink=1

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Six C300 controllers are used for controlling the whole plant

operation. The operational logic is stored in these controllers.

THE DCS SYSTEM IN PLANT OPERATION

Process Manager Input Output cards (PMI/Os) are providedfor data acquisition from field.

FTE(Fault Tolerant Ethernet) based communication networks

are used to provide communication between operating plants andcontrollers.

Field terminated Assembly Cards (FTA) provides path to thecontrol signals.

The signals are forwarded to the fields through cables.

The HMI system presents the information to the operatingpersonnel graphically, in the form of a mimic diagram. Thismeans that the operator can see a schematic representation of

the plant being controlled.

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FTA cardsHUMANMACHINEINTERFACE

CONTROLLER slots

TERMINALBLOCK(TB)

I TO PCONVERTER

CONTROLVALVE

Logicalprogramming Path for

transmission

Analog currentto pressureconversion

OPENING AND CLOSING OF CONTROL VALVE THROUGHDCS

Analog Feedback frompositioner

Through

cables

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The PID blockis a regulator control block that operates as a proportional-integral-derivative (PID) controller. It supports the Ideal form of calculatingthe PID terms.

The PID block has two analog inputs a process variable (PV) and a set

point (SP). The difference between PV and SP is the error and this blockcalculates the control output(OP) that would drive the error to zero.

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The following equations are supported:-

Proportional, Integral, and Derivative (PID) on the error

Proportional and Integral (PI) on the error and Derivative (D) onchanges in PV

Integral (I) on the error and Proportional and Derivative (PD) onchanges in PV

Integral (I) only

Proportional (P) only

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