SMEITS - Control and monitoring of hot-dip galvanizing process

32. Me unarodni kongres o procesnoj industriji, Beograd, 30-31. maj 2019đ32nd International Congress on Process Industry, Belgrade, May 30-31, 2019 1

Stanko STANKOV, Dragan ANTI , ĆMilutin PETRONIJEVI , Nikola DANKOVI , Ć ĆUniversity of Niš, Faculty of Electronic Engineering, Niš, Serbia

CONTROL AND MONITORING OF HOT-DIP GALVANIZING PROCESS


IntroductionOne of the most effective ways of protecting steel against corrosion is the hot-dip galvanizing of steel products.Process of hot-dip galvanizing is going through several stages; iron and steel products previously treated and cleaned, are being sunk into bathtub with melted zinc. During the process thin surface zinc layer which is resistant to corrosion, is formed. Control and monitoring system of this process is based on PLC and SCADA systems.Shift, daily and periodical reports with appropriate parameters and statistic data are generated and printed.


Tb M

Tb

M

M

Tb

M

M

RO

g11

RO

g10

RO

g9

ZBZI

NC

BA

THU

B

Coo

ling

cham

ber

(80

C)

C

M14.1

M14.2

E5

D1

M50

entrance of heated gases

M25

.2

M27.1

M26

M25

.1M

25.3

M25

.4M

25.5

M25

.6

cover

M29

M27.2M28.2M28.1

M30

manhole

M31

M M42.2

M42.1

M41.2

M41.1

B102

B101

L min

SC 3"

B66

YRV1M

+U

-UU

YRV9

U

+U

S11

Q1

L1

B21

14

15

L2 L3

PLC

HMI

D2

S12

E6 E7 E8

B22

18

Ex

E1 E2 E3 E4

Lmin

SB1

-U

9

M

+U

-UU

Deg

reas

ing

bath

tub

(60

C

)1

Bat

htub

for h

ot ri

nsin

g (4

0

C)

3

Bat

hubs

for p

ickl

ing

(10

C -

40

C)

65

47

8

Flux

ing

bath

tub

(80

C

)9

ZINC BATHTUB

M

M

M

M

YRV3

M

D1

Dry

ing

cham

bers

(10

0 - 1

20

C)

STEA

Mbo

iler

SB2 SB3E9 E10 E11

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2, ..

. , E

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urne

rs

Lmin

Lmin

D2

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f fan

s

Split

ter

B11 B12

B9

GALVANIZING

Bat

htub

for r

insi

ng (1

0 C

- 40

C

)

GA

LVA

NIZ

ING

(440

- 46

0 C

)

2 3 4 5 6 7 8

Col

lect

or

2

1

B2B1 B3 B4 B5 B6 B7 B8

C

Bio

dies

el ta

nk

Dai

ly b

iodi

esel

tank

YRV4 YRV5 YRV6 YRV7 YRV8

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ansh

ipm

ent p

umps

B10

Technological scheme of the hot-dip galvanizing plant

The hot-dip galvanizing plant consists of: •two degreasing bathtubs; •a hot-rinsing bathtub; •four pickling bathtubs; •a rinsing bathtub; •a fluxing bathtub; •two drying chambers; •a bathtub with melted zinc; •a cooling bathtub; •burners for heating the zinc bathtub; •steam boilers for heating other bathtubs.


SCADA screen of the plant for hot-dip galvanizing


SCADA screen of plant for neutralization of waste waters

The technological process of decontamination and neutralization of waste water is performed in the following phases:

•collection of all waste water and spent concentrates,•equalization of all waters,•neutralization,•control,•precipitation,•sludge treatment.


SCADA screen of the energy supply

•Room heating, water steam for technological processes, compression plant necessary for operation of the on/off and regulating electro-pneumatic valves are provided from the energy supply.

•Fuels: gas or biodiesel.

•Two boilers are operational, and the third one is in standby mode.


S7- 400

PRO

FIB

US

DP

S7-1200

KTP

1000

Chemical storage

KTP

1000

S7-1200

KTP

1000

Fire sprinkler system

Transform. station

and diesel agregate

S7-1200

KTP

1000

PROFINET

Industrial PC

PRO

FIN

ET

PROFINET

Profinet

Profinet

Profinet

Profinet

Scalance X208

PRO

FIB

US

PA

Scalance X208

SCADA server

S7-1200

Technical shift service

Technology

Compressor station

Maintenanceservice

Hot dip galvanization plant

COMMAND ROOMProfinet

S7-300

Wastewater treatment

Profinet

S7-3000

Boiler roomOPC server, SQL server,Web server

Block diagram of control-supervisory system for hot-dip galvanizing plant

•The hot-dip galvanizing machine (zinc bathtub with burners and other bathtubs) is controlled by the Simatic S7-400 master controller, which is designed for system solutions in the process industry with very demanding applications. •The control of individual technological units such as: transformer station and diesel generator, chemical store, fire sprinkler system and compressor stations are performed by local controllers Simatic S7-1200, and S7-300 controllers are used for control of the energy supply and the waste-water neutralization plant.•Controllers are connected with the master PLC controller through the Profibus industrial network.•The configuration and programming the controllers are done using Siemens software package TIA Portal (Totally Integrated Automation).


Control and monitoring systemStorage and presentation of information from all objects is carried out in the control

room where the servers and workstations are installed:master SCADA server - the main server in the system in which the real-time data

from all objects is located and it performs the presentation of these data for workstations (large number of screens) and generates all types of graphic and table reports based on archived data;

master SQL server stores all types of information that are collected in the main SCADA server in the relational database, in order to display and analyze this information later;

spare (backup) SQL server - redundant server in the system, which gets the data by "replication" from the master SQL server;

domain ("domain control") server provides the correct domain work of the whole SCADA system with all the services required by this complex;

Web server

di

1 de(t)LMN GAIN e(t) e(t)dt TT dt

= + +

∫

sτKW(s) e1 Ts

−=+ The transfer function of the process of heating the

solution

GAIN - controller gain ; e (t) - error; Ti -integration time constant; Td - differential time constant; t-time; LMN - value of the control variable formed depending on the current error value (P action); depending on how the error was changed in the previous period (I action), and depending on the current tendency of the error (D action).


Recorded step response of the heating process and the model response


Controller type

P

PI

PID

Higher order

rTvτ

=

rv 10>

r7.5 v 10< <

r3 v 7.5< <

rv 3<

Controller type

P - -

PI -

PID

K iT dT

r

p

0.3vK

r

p

0.35vK

1,2τ

r

p

0.6vK

T 0,5τ

K = 1.012, τ = 168 s, T = 890 s.

rTv 5.3τ

= =

Determining controller type

by using CHR method

Adjusting controller parameters for aperiodic response by CHR method

p

0.6TGain 3.14τK

= =

iT T 890s= =

dT 0.5τ 84s= =

P

I

D


Time dependences of the steam temperature and the solution temperature


ConclusionThe paper describes the configuration of the control and monitoring system for the hot-dip galvanizing process.The variables characteristics for the hot-dip galvanizing process is monitored on the SCADA computers.The system generates and upon request, prints change and periodic reports with appropriate parameters and statistical data.An example of the solution temperature control in the degreasing bathtub is given.The procedure for adjusting the PID controller which allows one very inert process to be carried out without error and oscillations is shown.


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SMEITS - Control and monitoring of hot-dip galvanizing process

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