APC Instrumentation View

7/30/2019 APC Instrumentation View

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Advanced Process Control

Sanjeev Sharma


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Contents

Process controlAdvanced Process Control (APC) Defined

Applications, Advantages & Limitations

Basic Process Control

Feedback ControlFeedforward Control


Instrumentation in APC

Upkeep methodsSummary


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Process Control

Process : Process is any method of converting a raw material

into end products

Process Control : Methods that are used to control processvariables when manufacturing a product

Why Process Control??

Reduce Variability

Increase EfficiencyEnsure Safety


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Simple LoopsOpen Loops

Closed Loop

Cascaded Loop

Crude Crude

HIC-1105

MV xxxx

Naphtha Naphtha

FI-1101 m3/hr

Naphtha Naphtha

FI-1101 m3/hr

FIC-1101

SV xxxx m3/hr

PV xxxx m3/hr

AL

80 %FIC-1101

SV xxxx m3/hr

PV xxxx m3/hr

AL LIC-1101

SV xxxx %

PV xxxx %

AL

Naphtha Naphtha

FI-1101 m3/hr

80 %

80 %


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Control Strategies: Real Life example


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Regulatory ControlPID control : PID control is most popular as

It gives good performance for single loops

It is applicable for wide range of processes by changing

its tuning parameters

Condensate

PIDError

Sensor

Cold Fluid

Hot Fluid

MV

SP+-

Steam


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Regulatory Control

Feed forward Control

Feed forward control is a control system that anticipates loaddisturbances and controls them before they can impact the

process variable. For feed forward control to work, the user must have

a mathematical understanding of how the manipulated variables will

impact the process variable.

Fig. shows a simple feed forward loop in

which a flow transmitter opens or closes a

hot steam valve based on how much cold

fluid passes through the flow sensor


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Combinations of feedback and feedforward control are

usedBenefits of feedback control: controlling unknown disturbancesand not having to know exactly how a system will respond

Benefits of feedforward control: responding to disturbances

before they can affect the system

Combined Feedforward/Feedback


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Most complex processes have many variables that have

to be regulatedTo control multiple variables, multiple control loops mustbe used

Example is a reactor with at least three control loops:temperature, pressure and level (flow rate)

Multiple control loops often interact causing processinstability

Multivariable controllers account for loop interaction

Models can be developed to provide feedforward controlstrategies applied to all control loops simultaneously

Multivariable Control


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State-of-the-art in Modern Control Engineering Appropriate for Process Systems and

Applications

APC: systematic approach to choosing relevanttechniques and their integration into a

management and control system to enhance

operation and profitability



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Key process

variables

Management

Objectives

APC is a step beyond Process Control

Built on foundation of basic process control loops

Process Models predict output from key process variables

online and real-time

Optimize Process Outputs relative to quality and profitabilitygoals


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APC instrumentation defines, creates and maintains an

APC system. It also allows controlled access to various

tools & data in the database. It is a combination of many

components:

Instrumentation in APC

APC


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14.13

APC SYSTEM ARCHITECTURE

250msec-1sec.

1sec. screenrefresh rate

between 2-5sec.

< 1 min.

> 1 min.


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APC cannot be implemented as a standalone system

without the base networks where speed plays animportant role.

Field Instrument Network based on IEEE 802.4 (ISO

8802/4). It operates at a 5 megabit/second rate using

efficient message structures to support the high-speed

communications requirements of a process network.Process Control Network such as Device Level ring

network operates at 100Mbps.

Process Information Network such as Historian System

such as dedicated Ethernet network operates at100Mbps.

Enterprise Network e.g. Local Area Network (LAN).

Speed is 1000Mbps.

APC System Architecture


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A Solid Field Instrumentation is Essential to the

Success of Any APC project.

The core of a solid foundation is good measurements

and final elements.

Deficiencies in the measurement and final element canincrease the time required for process testing and

identification by a factor of 5 or more and can

significantly reduce the improvement in process capacity

and efficiency provided by APC.

Field Instrumentation


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The largest opportunity for final elements if to eliminatestickslip (spontaneous jerking) and deadband.

The largest opportunity for measurements is the

selection and installation of sensors.

Check the life-cycle cost, including the cost of variabilitybefore choosing a less expensive control valve or

measurement.

Use smart transmitters. The improved accuracy and

diagnostics are worth the extra cost. Use Fieldbus for

major upgrades and new installations.

Field Instrumentation Rules Of Thumb


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APC Hardware


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Gateway

Gateway station acts as a gateway between DCS andAPC with the latest OPC Technology. As Gatway

station is a node on the control bus itself and hence

no additional communication programming is

required. This also reduces the loading on the control

bus.


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Features of Gateway

Data Thru-put: 2000 data per second.Interconnecting to other third party soft wares like

Scheduling, planning, Data Reconciliation, SAP

extremely easy.

Communication is an Event based, which reduces thebusload as well as the Client application will not be

always busy polling data request.

The protocol is standard OPC specifications.

Message transfer from DCS is also as per the standard OPC

specifications OPC A&E Version 1.0. User has the authorityto select.

Communication interface for each DCS system is same

(OPC).


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Features of Gateway

OPC Server maintains history. There is no limit ofhistory duration, it only depends upon the hard disk

capacity of the OPC server.

Quality flag is always associated with each data. User will

immediately know the quality of the information.Every time the tag database is changed, client applications

will get the information from the OPC server itself so

absolutely no need to reconfigure the database.

Database Equalization is the main positive point of OPC

station.


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APC Operator/Engineering Station

Man Machine InterfaceParameters are monitored / changed from this station

It maintains history too. Accordingly Hard Disk Drive is

sized.

HMI displays form integral part of the APC station.Parameter changes from this station are reflected in

DCS operator station through OPC server.

Hardware of APC station & Gateway is generally same.


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Specifications of Gateway & APC station

Fi ll


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Firewall

Introduction

Type of Firewalls

I t d ti


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Introduction

Firewalls control the flow of network traffic

Firewalls have applicability in networks

where there is no internet connectivity

Firewalls operate on number of layers

Can also act as VPN gateways

Active content filtering technologies

Type of Firewalls


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Type of Firewalls

Firewalls fall into four broad categories

Packet filters

Circuit levelApplication level

Stateful multilayer

Packet Filter


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Packet Filter

Work at the network level of the OSI

model

Each packet is compared to a set of

criteria before it is forwarded

Packet filtering firewalls is low cost and

low impact on network performance

Packet Filtering


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Packet Filtering

Circuit level


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Circuit level

Circuit level gateways work at the session

layer of the OSI model, or the TCP layer of

TCP/IP

Monitor TCP handshaking between

packets to determine whether a requested

session is legitimate.

Circuit Level


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Circuit Level

Application Level


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Application Level

Application level gateways, also called

proxies, are similar to circuit-level

gateways except that they are application

specific

Gateway that is configured to be a web

proxy will not allow any ftp, gopher, telnet

or other traffic through

Application Level


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Application Level

Stateful Multilayer


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Stateful Multilayer

Stateful multilayer inspection firewalls

combine the aspects of the other three

types of firewalls

They filter packets at the network layer,

determine whether session packets are

legitimate and evaluate contents of

packets at the application layer

Stateful Multilayer


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Stateful Multilayer

General Performance


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General Performance

I t t t f APC G t & APC HMI t ti


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Important parameter of APC Gateway & APC HMI station

APC machines are built on strong and ruggedhardware with more emphasis on availability

R A I D configuration of hard disks is preferred.

RAID (Redundant Array of Independent Disks)

Types of RAID

What type we Use

RAID


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RAID

Redundant Array ofIndependent Disks

Redundant Array ofInexpensive Disks

RAID 0

RAID 1

RAID 3

RAID 5

RAID 6

Types of redundancy


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Types of redundancy

There are different levels of redundancy:

none if a disk crashes, data is lost

RAID1 2 disks are mirrored, data is written to

both disks at any time. One disk can be lost

without losing data.

DATA

DATA

DATA

disk

disk

disk

Types of redundancy


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Types of redundancy

RAID3, RAID5 data is distributed across several

disks, data parity (error protection scheme), usedto rebuild a defective drive, is either placed on a

dedicated drive (RAID3) or across all drives

(RAID5):

DATA DATA

disk disk

PARITY DATA

disk disk disk

RAID3 RAID5

DATA

PARITYPARITY

DATA

DATADATA

PARITY

DATA

disk

RAID 5


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RAID 5

Striping+DistributedParity (errorprotection scheme)

Data is written across multiple disks(striping). Parity is written across alldisks (usually XOR based).

Commonly RAID Controller Failure


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Commonly RAID Controller Failure

What is the problem?Failure of RAID card

Reason:

Earthing problem

Ageing of components.

Precautions:Ensure proper earthing.Wear anti-static wristband while doingmaintenance.Keep a hot spare RAIDCard in hand.

APC Software


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APC Software

Software for Gateway & APC stationincludes Interface package for DCS

along with HMI application software,

OPC client and Antivirus software.

Other APC software details


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Other APC software details

Backup


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Backup

What is backup?backup is part of a larger domain called datasecurity:

integrity, protection: cryptography

availability, redundancy: mirroring / RAID

Why Backup?Software and Hardware failures are a common

thing in the computer world. Any number of

occurrences can cause loss of valuable data.

Why the data is lost?


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Why the data is lost?

Due to failures

Power failures (software/hardware failure)Security incidents

Hardware Failures (disk crash)

Followed backup strategy


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Followed backup strategy

This is driven by many variables. Such as:

Levels of backup:

Daily

Quarterly

Annually

Daily: Tuning parameters or after modification

Quarterly: Major parameter backup during AMC visit

Annually: Complete backup of the system

Virus


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Virus

What is Computer virus

Types of viruses

Introduction to Antivirus Program

How an Antivirus worksGeneral precautions you should take

What is a Computer Virus?


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What is a Computer Virus?

A computer virus is a small program written to alter the

way a computer operates, without the permission or

knowledge of the user. With an ability to replicate itself,

thus continuing to spread. Also, known as Malicious

Software, a program that can cause damage to acomputer.

The computer viruses can damage or corrupt data,

modify existing data, or degrade the performance of thesystem by utilising resources such as memory or disk

space.

Classification of Computer viruses:


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Classification of Computer viruses:

Boot sector virus

Master Boot Record (MBR) virus

File infector virus

Multipartite virusMacro virus

Boot sector virus


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Boot sector virus

Boot sector viruses generally hide in the boot sector,either in the bootable disk or the hard drive.

It attaches itself to the first part of the hard disk that isread by the computer upon boot up.

These viruses are spread rapidly by floppy disks and noton CD-ROMs.Once copied to the memory, any floppy disks that arenot write protected will become infected when the floppydisk is accessed.

Errormessage Invalid system disk

E.g. Form, Disk Killer, Michelangelo, Stoned.



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MBR viruses are memory-resident viruses that infect

disks in the same manner as boot sector viruses.

However it, infects the MBR of the system, gets

activated when the BIOS activates the Master boot code.

MBR infectors normally save a legitimate copy of the

master boot record in an different location.

E.g. AntiEXE, Unashamed, NYB

File infector virus


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File infector virus

File infector viruses infect program files.

Normally infect executable code, such as .COM, .SYS,

.BAT and .EXE files.

They can infect other files when an infected program is

run from floppy, hard drive, or from the network. Many of

these viruses are memory resident.

After memory becomes infected, any uninfected

executable file that runs becomes infected.

E.g. Snow.A, Jerusalem, Cascade.

Multipartite virus


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Multipartite virus

Multipartite (also known as polypartite) viruses infect

both boot records and program files.

These are particularly difficult to repair. If the boot area is

cleaned, but the files are not, the boot area will be

reinfected.

The same holds true for cleaning infected files. If the

virus is not removed from the boot area, any files that

you have cleaned will be reinfected.

E.g. One_Half, Emperor, Anthrax, Tequilla.

Macro virus


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Macro virus

Macro are mini-programs which make it possible toautomate series of operations so that they are performedas a single action, thereby saving the user from havingto carry them out one by one.

Macro viruses infect files that are created using certain

applications or programs that contain macros.They are platform-independent since the virus itself arewritten in language of the application and not theoperating system.

They infect documents created from Microsoft OfficeWord, Excel, PowerPoint and Access files.

E.g.W97M.Melissa, Bablas, WM.NiceDay, W97M.Groov.


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In addition to Computer viruses, there are

two more types of malicious software.

These are : Worms and Trojans

Computer Worms


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Computer Worms

Worms are programs that replicate themselves fromsystem to system without the use of a host file. Theworms are spread through networks like LAN, WAN andalso through Internet. There are various ways by which aworm spreads, through Internet like E-mails, Messaging

and Chats.

Worms almost always cause harm to the network, likeconsuming network bandwidth.

E.g.W32.Mydoom.AX@mm

Computer Trojans


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Computer Trojans

Trojan horses are impostors: files that claim to besomething desirable but, in fact, are malicious. Trojanhorse programs do not replicate themselves. Trojanhorses contain malicious code that when triggered causeloss, or even theft, of data. E.g. Trojan.Vundo

Retrieving users critical information. i.e. name, password.

Spreading malware programs i.e. dropper or vector.

Erasing or overwriting data on a computer.

Spying on a user to gather his information like browsing habits,sites visited etc. These are called Spyware.

General precautions we take


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General precautions we take

When inserting removable media (floppy, CD, flash drive

etc.) we scan the whole device with the antivirus

software before opening it.

If with internet access, we use internet security software.

Regularly check Windows updates.

Dont open any unknown exe file.

From time to time, update our installed software to their

latest version. E.g. (MS Office, Adobe Reader, java,

Flash player etc.)

Summary


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Summary

The advent of powerful and friendly integrated software

has moved advanced process control (APC) from the

realm of consultants into the arena of the average

process control engineer.

There is a opportunity of the engineers closest to theprocess and daily operation to take a much more active

role in the development and support of APC applications.

The core of a solid foundation is good measurements

and final elements.

Summary


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Summary

Use smart transmitters. The improved accuracy and

diagnostics are worth the extra cost. Use Fieldbus for

major upgrades and new installations.

Examines how to identify advanced process control

opportunities, estimate benefits, select the besttechnology, sustain the solution, track the benefits.

Industry is driven by cost and benefit analysis and is

generally not interested in a great technology looking for

an application.


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Thanks

Questions??

Documents

APC Instrumentation View