kendali - 1 - pendahuluan

1Pengendalian Proses Kimia

Bambang Heru SusantoDepartemen Teknik Kimia

FTUI

Bab 1

Pendahuluan

Proses dalam kehidupan

--Susah untuk di kontrol

Operasi pemrosesan didalam industri kimia dan

bio

---Kita dapat kontrol

Pertanyaan

Setelah lulus

Apa yang menjadi rencana anda selanjutnya?

Dimana anda akan melihat diri anda sendiri

dalam 10 tahun kedepan?

2Desain Proses v.s. Kontrol Proses

Desain proses: estimasi ongkos kapital danoperasi; memperkenalkan desain danstrateginya.

Mempertimbangkan dinamika proses danisu pengendalian sejak awal desain proses.

Tujuan Perkuliahan

Memperoleh dan menganalisa data dari proses dinamik.

Membuat/mengembangkan model mekanistik dan empiris (data-based)

untuk proses tertentu. Termasuk aplikasi dari persamaan kekekalan masa-

energi untuk kondisi un-steady state.

Desain sistem kontrol menggunakan teknik feedback, feedforward, dll.

Evaluasi stabilitas dan karakteristik lainnya yang berhubungan dengan

pengendalian proses.

Pengendalian proses bio (ini baru nih !)

Filosofi Pengendalian Proses

Pemodelan Dinamik

(Mekanistik)

Analisis Perilaku

Model Dinamik

Pengendalian Proses

Pemodelan Empirik

Pengendalian Proses

Penyetelen

KontrolerAnalisis

Stabilitas

Mata Ajar

SebelumnyaMata Ajar

Sedang Berjalan

SIMULASI

(LAB. MAYA)

MODUL

INTERAKTIF

Next

VIDEO

Lecture

Notes

Disain

Pembelajaran SAP

Metode

WILMO

Pengertian Dasar dan Keahlian yang

Berhubungan dengan Industri

Pengertian Dasar Laplace transforms dan transfer functions

Block Diagram

Perilaku sistem dinamik

Analisis Frequency response

Berkaitan dengan Industri Peralatan kontrol (Control hardware) dan troubleshooting

Implementasi Pengendali dan tuning

Sistem Kontrol

Teknik PID

Pengendalian MIMO

3Penilaian :

Penilaian : UTS 25 %

UAS 25%

Kuis 20 %

PR 10 %

Makalah 20 %

Absensi 5%

Total 105 %

Makalah (Kelompok 3 orang)

Baca artikel-artikel di jurnal (misal Journal of Process Control) ataupunsumber lainnya yang berkaitan dengan kasus pengendalian pada industrikimia (5 tahun terakhir).

Jadikan dalam makalah 8 -10 halaman ( 1.5 spasi)

Dikumpulkan dan Dipresentasikan (10 menit per kelompok) pada Jumat 15 Oktober 2010

Outline: Judul, Pendahuluan, Tujuan, Studi literatur (review), Diskusi, Perhitungan, Kesimpulan, Daftar pustaka.

Sistem kontrol didalam metabolisme selular (misal.

feedback control)

Permasalahan pengendalian pada industri bio tertentu

Perbandingan anatara beberapa metode penyesuaian

(tuning) pengendali

Modeling/Simulasi/Software

Reaktor didalam lab/novel (kontrol pH, Temp, oxigen,

dll): terutama untuk micro-bioreactor

Remediasi dan kontrol polusi

Biologi sintetis untuk industri bahan bakar

Topik (bisa beragam sesuai keinginan)

Ajukan pada pertemuan tanggal 6 September 2010Karir di bidang Kontrol Proses

Memerlukan engineer yang mampu menerapkan semua

pelatihan rekayasa kimia dan bio process engineer

Dapat menjadi seorang engineer Top Gun

Memberikan peluang engineer untuk berkarya dalam suatu

projek yang menghasilkan penghematan yang signifikan

pada suatu perusahaan

Menyediakan mobilitas profesional. Masih sangat kurang

engineer berpengalaman yang memahami kontrol proses

Gaji yang baik dan menjajikan (terutama di luar

negeri/negara maju)

4Tugas Control Engineer

Tuning pengendali untuk

mempertahankan/meningkatakan unjuk

kerja dan kehandalan

Menselksi model kontrol yang sesuai

Memecahkan permasalahan pengendalian

proses dan mendokumnetasikan

perubahannya.

Industri Proses Kimia (CPI) Bahan bakar hidrokarbon

Produk-produk kimia

Produk pulp dan kertas

Agrokimia

Man-made fibers

Industri Proses-Bio Menggunakan micro-organisms untuk menghasilkan

produk yang bermanfaat

Industri farmasi

Etanol dari industri gandum/jagung/ketela

Perbedaan CPI dan Proses Bio Proses bio kebanyakan tidak kontinyu

Sistem bio mempertahankan kondisi steril selama proses

berlangsung

Daerah stagnan harus dikurangi dalam sistem bio untuk

mencapai kemampuan membersihakan, steril dan

mempertahankan lingkungan yang seragam untuk

mikroorganisme

Proses bio yang berkaitan dengan produk yang dikonsumsi

manusia harus mendapatkan izin dari BPOM

Kebanyakan siste bio memiliki unit prouski yang lebih

kecil dari proses pad CPI

Pemisahan bio berbeda dengan pemisahan pada CPI

Pentingnya Kontrol Proses untuk CPI

dan Proses-Bio

KP secara langsung mempengaruhi

keselamatan dan kehandalan dari sebuah

proses

KP menentukan kualitas produk yang

dihasilkan oleh suatu proses.

KP dapat mempengaruhi efesiensi sebuah

proses.

Bottom Line: KP memiliki dampak utama

terhadap keuntungan sebuah perusahaan.

5Keamanan dan Kehandalan

Sistem kontrol harus menyediakan proses

operasi yang aman

Alarm, safety constraint control, start-up dan

shutdown.

Sistem kontrol harus dapat meng-absorb

berbagai gangguan dan menjaga proses

tetap dala rentang operasi yang baik. :

Gangguan badai, perubahan komposisi umpan,

kekurangan secara berkala utilitas (suplai

steam), variasi operasi siang-malam dalam

kondisi ambient

Tujuh (7) Obyektif Pengendalian

1. Kesalamatan (safety)

2. Proteksi lingkungan

3. Proteksi peralatan

4. Operasi yang lancar

5. Kualitas produk

6. Profit

7. Memonitor dan mendiagnosis

CONTOH PROSES: FLASH SEPARATION

19

Feed

Methane

Ethane (LK)

Propane

Butane

Pentane

Vapor

product

Liquid

productProcess fluid Steam

F1

F2 F3

T1T2

T3

T5

F4

T6 P1

L1

A1

L. Key

Mari kita diskusikan

proses ini

P 1000 kPa

T 298 K

Tujuh Obyektif Pengendalian

20

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key





5. Kualitas produk

6. Profit


Beri contoh

6Tujuh Obyektif Pengendalian

21





5. Kualitas produk

6. Profit


Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 PC

L1

A1

L. Key

Tekanan tinggi

di dalam drum

adalah bahaya


22

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key

Beri contoh1. Kesalamatan (safety)




5. Kualitas produk

6. Profit



23

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key

Tidak pernah

melepas hidrokarbon

ke atmosfir

To flare





5. Kualitas produk

6. Profit



24

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key





5. Kualitas produk

6. Profit



25

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

LC

A1

L. Key

Tidak ada aliran

yang dapat

merusak pompa





5. Kualitas produk

6. Profit



26

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key

Beri contohnya1. Kesalamatan (safety)




5. Kualitas produk

6. Profit



27

Feed

Vapor

product

Liquid

productProcessfluid

Steam

FC

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key

Selalu menjaga

kelancaran laju

produksi





5. Kualitas produk

6. Profit



28

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key





5. Kualitas produk

6. Profit



29

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

AC

L. Key

Mencapai L.Key

dengan menyesuaikan

pemanasan1. Kesalamatan (safety)




5. Kualitas produk

6. Profit



30

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key





5. Kualitas produk

6. Profit



31

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

AC

L. Key

Gunakan

pemanasan

semurah mungkin





5. Kualitas produk

6. Profit



32

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key





5. Kualitas produk

6. Profit



33

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key

Hitung dan plot

parameter kunci,

misal, UA.

waktu

UA





5. Kualitas produk

6. Profit



34

Feed

Vapor

product

Liquid

productProcessfluid

Steam

F1

F2 F3

T1 T2

T3

T5

T4

T6 P1

L1

A1

L. Key

Ketujuh-tujuhnya harus dicapai. Gagal untuk

melakukan yang demikian akan

berakibat operasi yang tidak menguntungkan

atau lebih buruk lagi, tidak selamat.





5. Kualitas produk

6. Profit


Contoh: stirred tank heater

Tc

To, Fo, Xo

X, F, T

Thermocouple

Controller

Set-point

Sistem Kontrol Komponen Sistem

Operator dials in a set-

point (desired

temperature)

Thermocouple measures

temperature in tank

Measured temperature is

compared to set-point

Controller manipulates

steam valve based on

difference between set-

point and measurement

Tc

To, Fo, Xo

X, F, TTc

To, Fo, Xo

X, F, T

Thermocouple

Controller

Set-point

10

Example: stirred tank heater

Tc

To, Fo, Xo

X, F, T

Thermocouple

Controller

Control Systems System components

Operator develops model of system

Thermocouple measures temperature in inlet stream

Measured temperature is input to process model

Controller manipulates steam valve based on model prediction

Tc

To, Fo, Xo

X, F, TTc

To, Fo, Xo

X, F, T

Thermocouple

Controller

ProcessManipulated

variablesControlled

variables

Disturbance

variables

General representation of a control problemDriving a Car: An Everyday Example of Process

Control

Control Objective (Setpoint): Maintain car in proper lane

Controlled variable: Location on the road

Manipulated variable: Orientation of the front wheels

Actuator: Drivers steering wheel

Sensor:

Drivers eyes

Controller: Driver

Disturbance:

Curve in road

11

Schematic of Feedback Loop

Car example

Driving

a car

Drivers

eyes

Current

location on

road

Curve in road

Steering

wheel

Drivers

brain+

-

Where the

driver

wants to go

Signal from

eyes to

brain

Schematic of Feedback Loop

General diagram

Actuator

Sensor

Process

Controlled

Variable

Disturbance

uController

cSetpoint+

-

e

Manipulated

variable

Controlled

variable

Error

Heat Exchanger Control:

ChE Control Example

TT

TC

Condensate

Steam

Feed

Product

Stream

ISA standard (Instrument Society of America)

The first letter defines the measured or initiating variables:

Analysis (A), Flow (F), Temperature (T), Level (L), Pressure (P), Quantity (Q),

Weight/Force (W).

Succeeding letters define readout, passive, or output functions:

Alarm (A), Control (C), Indicator (I), Record (R), Transmit (T), Actuator/Driver

(Z)

Pneumatic signal (solid line) and electronic signal (dash line)

Example: Sensor-Transmitter (AT); Feedback control

(AC); Current-to-pressure transducer (I/P)

12

Heat Exchanger Control

Controlled variable

Outlet temperature of product stream

Manipulated variable

Steam flow

Actuator

Control valve on steam line

Sensor

Thermocouple on product stream

Disturbance

Changes in the inlet feed temperature

Selection of controlled, manipulated, and

measured variables

Controlled variables

Control non-self-regulating variables

(unbounded response)

Within equipment and operating constraints

Direct measurable/interact with other controlled

variables

Favorable dynamic characteristics (no long

time delays)

Selection of controlled, manipulated, and

measured variables

Manipulated variables

Large effect on controlled variable

Rapid and direct effect

Avoid recycling of disturbances

Measured variables

Reliable and accurate

Sensitive (avoid dead zone and time delays, e.g., dead zone in batch)

Keuntungan dari Peningkatan

Sistem Kontrol

Time

Impuri

ty

Conce

ntr

ati

on

Limit

Time

Impuri

ty

Con

centr

ati

on

Limit

Old Controller New Controller

13

Kotrol Yang Lebih Baik Berarti Memperbaiki

Produk dengan Mengurangi Variabilitas

Untuk beberapa kasus, mengurangi

variabilitas produk adalah merupakan

tuntutan dan memiliki nilai tambah tinggi

(contoh bahan baku untuk polimer)

Prosedur sertifikasi produk (yaitu ISO

9000) digunakan untuk menjamin kualitas

produk dan menempatkan banyak

penekanan pada kontrol proses.

Keuntungan dari Peningkatan

Sistem Kontrol

Time

Impuri

ty

Conce

ntr

ati

on

Limit

Time

Impuri

ty

Con

centr

ati

on

Limit

Time

Impuri

ty

Conce

ntr

ati

on

Limit

Old Controller New Controller

Improved Performance

Maximizing the Profit of a Plant

Many times involves controlling against

constraints.

The closer that you are able to operate to

these constraints, the more profit you can

make. For example, maximizing the

product production rate usually involving

controlling the process against one or more

process constraints.

Constraint Control Example

Consider a reactor temperature control

example for which at excessively high

temperatures the reactor will experience a

temperature runaway and explode.

But the higher the temperature the greater

the product yield.

Therefore, better reactor temperature

control allows safe operation at a higher

reactor temperature and thus more profit.

14

Importance of Process Control for the

Bio-Process Industries

Improved product quality.

Faster and less expensive process validation.

Increased production rates.

Driving a Car: An Everyday

Example of Process Control

Control Objective (Setpoint): Maintain car in

proper lane.

Controlled variable- Location on the road

Manipulated variable- Orientation of the front

wheels

Actuator- Drivers arms/steering wheel

Sensor- Drivers eyes

Controller- Driver

Disturbance- Curve in road

Logic Flow Diagram for a

Feedback Control Loop

Temperature Control for a Heat

Exchanger: ChE Control Example

15

Heat Exchanger Control

Controlled variable- Outlet temperature of

product stream

Manipulated variable- Steam flow

Actuator- Control valve on steam line

Sensor- Thermocouple on product stream

Disturbance- Changes in the inlet feed

temperature

DO Control in a Bio-Reactor

DO Control

Controlled variable- the measured dissolved O2 concentration

Manipulated variable- air flow rate to the bio-reactor

Actuator- variable speed air compressor

Sensor- ion-specific electrode in contact with the broth in the bio-reactor

Disturbance- Changes in the metabolism of the microorganisms in the bio-reactor

Logic Flow Diagram for a

Feedback Control Loop

16

Comparison of Driving a Car and

Control of a Heat Exchanger

Actuator: Drivers arm and steering wheel

vs. Control valve

Controller: the driver vs. an electronic

controller

Sensor: the drivers eyes vs. thermocouple

Controlled variable: cars position on the

road vs. temperature of outlet stream

The key feature of all feedback control

loops is that the measured value of the

controlled variable is compared with

the setpoint and this difference is used

to determine the control action taken.

In-Class Exercise

Consider a person skiing down a mountain.

Identify the controller, the actuator, the

process, the sensor and the controlled

variable. Also, indicate the setpoint and

potential disturbances. Remember that the

process is affected by the actuator to change

the value of the controlled variable.

Types of Feedback Controllers

On-Off Control- e.g., room thermostat

Manual Control- Used by operators and based on

more or less open loop responses

PID control- Most commonly used controller.

Control action based on error from setpoint

(Chaps 6-8).

Advanced PID- Enhancements of PID: ratio,

cascade, feedforward (Chaps 9-11).

Model-based Control- Uses model of the process

directly for control (Chap 13).

17

Duties of a Control Engineer

Tuning controllers for performance and

reliability (Chap 7)

Selecting the proper PID mode and/or

advanced PID options (Chap 6, 10-12)

Control loop troubleshooting (Chap 2 & 8)

Multi-unit controller design (Chap 14)

Documentation of process control changes

Characteristics of Effective

Process Control Engineers

Use their knowledge of the process to guide

their process control applications. They are

process control engineers.

Have a fundamentally sound picture of

process dynamics and feedback control.

Work effectively with the operators.

Operator Acceptance

A good relationship with the operators is a

NECESSARY condition for the success of a

control engineer.

Build a relationship with the operators

based on mutual respect.

Operators are a valuable source of plant

experience.

A successful control project should make

the operators job easier, not harder.

Process Control and

Optimization

Control and optimization are terms that are

many times erroneously interchanged.

Control has to do with adjusting flow rates

to maintain the controlled variables of the

process at specified setpoints.

Optimization chooses the values for key

setpoints such that the process operates at

the best economic conditions.

18

Optimization and Control of a CSTROptimization Example

balances.

molefromcalculatedareandLikewise,

]/exp[1

forSolving

]/exp[

:AonbalanceMole

11

0

110

CB

r

AA

A

rAAA

CC

Q

VRTEk

CC

C

VCRTEkCQCQ

CBA

+

=

Economic Objective Function

AFACCBBAA VCQVCQVCQVCQ 0++=

VB > VC, VA, or VAF

At low T, little formation of B

At high T, too much of B reacts to form C

Therefore, the exits an optimum reactor

temperature, T*

Optimization Algorithm

1. Select initial guess for reactor

temperature

2. Evaluate CA, CB, and CC

3. Evaluate

4. Choose new reactor temperature and

return to 2 until T* identified.

19

Graphical Solution of Optimum

Reactor Temperature, T*

-0.5

0

0.5

1

1.5

2

250 275 300 325 350

Reactor Temperature (K)

Eco

no

mic

Obje

ctiv

e

Fu

nct

ion

,

T *

Process Optimization

Typical optimization objective function, :

= Product values-Feed costs-Utility costs

The steady-state solution of process models

is usually used to determine process

operating conditions which yields flow rates

of products, feed, and utilities.

Unit costs of feed and sale price of products

are combined with flows to yield

Optimization variables are adjusted until

is maximized (optimization solution).

Generalized Optimization

Procedure

Aumerical

Optimization

Algorithm

Process

Model

Economic

Parameters

Economic

Function

Evaluation

Optimization

Variables

Economic

Function

Value

Model

Results

Initial Estimate

of Optimization

Variables

Optimum

Operating

Conditions

Optimization and Control of a CSTR

20

In-Class Exercise

Identify an example for which you use

optimization in your everyday life. List the

degrees of freedom (the things that you are

free to choose) and clearly define the

process and how you determine the

objective function.

Overview of Course Material

Control loop hardware (Chap 2)

Dynamic modeling (Chap 3)

Transfer functions and idealized dynamic

behavior (Chap 4-6)

PID controls (Chap 7-10)

Advanced PID controls (Chap 12-14)

Control of MIMO processes (Chap 15-18)

Fundamental Understanding and

Industrially Relevant Skills

Fundamental Understanding-

Laplace tranforms and transfer functions (Ch 4-5)

Idealized dynamic behavior (Ch 6)

Frequency response analysis (Ch 11)

Industrially Relevant Skills-

Control hardware and troubleshooting (Ch 2&10)

Controller Implementation and tuning (Ch 7-9)

Advanced PID techniques (Ch 12-14)

MIMO control (Ch 15-18)

Process Control Terminology

Important to be able to communicate with

operators, peers, and boss.

New terminology appears in bold in the text

New terminology is summarized at the end

of each chapter.

Review the terminology regularly in order

to keep up with it.

21

Overall Course Objectives

Develop the skills necessary to function as

an industrial process control engineer.

Skills

Tuning loops

Control loop design

Control loop troubleshooting

Command of the terminology

Fundamental understanding

Process dynamics

Feedback control

Overview

All feedback control loops have a

controller, an actuator, a process, and a

sensor where the controller chooses control

action based upon the error from setpoint.

Control has to do with adjusting flow rates

to maintain controlled variables at their

setpoints while for optimization the

setpoints for certain controllers are adjusted

to optimize the economic performance of

the plant.

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