Simplified Approach for Paper Drying Modeling Using Matlab

Simplified Approach for Paper Drying Modeling Using Matlab

International Journal of Engineering Research & Technology (IJERT)

ISSN: 2278-0181

Vol. 2 Issue 2, February- 2013

Shweta Goyal, Swati Gargust, Mandeep Guleria

M-Tech in Instrumentation & Control GRAPHIC ERA UNIVERSITY DEHRADUN

Index TermsIntroduction, Factors affection drying process, what is Matlab, Model Equation, Matlab Models,results

Abstract

In this proposed work model for the paper drying process has been designed in Matlab Simulation toolbox developed, for modeling ,the drying section divides into component such as PAPER,CANVAS,AND CYLINDERS. The

dynamic model of these component are represented as lumped parameter system and connected to each other to model the entire paper drying process. Matlab simulation helps in developing model for paper dryer. simulation studies are carried out to study the effect of grade change and other process variables on the final moisture of the paper. the novel approach of modeling the paper dryer as lumped parameter system reduced he numerical complexity of the model

Introduction

Paper is used for printing and writing, for wrapping and packaging and for a variety of other application ranging from kitchen towel to the manufacture of building material , it simply comes in an enormous variety of quantities. Some common types of paper qualities include the following:

• Copy paper for printer

• Newsprint

• Cardboard

• Light-weight coated paper for magazines

• Wrapping and packaging paper

• Currency paper

The function of a paper machine is to form the paper

sheet and remove the water from the sheet. A paper machine is divided into three main parts, the wire section, the press section and the drying section shown in fig 1.1, when a stock enters the head box in the wire section it contains roughly 1% of fiber or less. The viscous mix is dispensed through a long slice onto the wire. As it travels on the wire, mu of the water drains way by gravitational forces or is pulled away by suction from underneath. As a water disappears, the cellulose fiber starts to adhere to one another by hydrogen bonds and form a paper web. when the paper web leaves the wire section and enters the press section ,the dry solids content around 20%. In the press section, the newly formed

sheet is pressed between rotating steel rolls and water is displaced into a press felt. After a few press nips the web enters the drying section with a solid content of approximately about 50%. It now encounters the dryer cylinders. These are large hollow metal cylinders, heated internally with steam, which dry the paper as it passes them, Finally the paper wound up on a big roll and removed from the paper machine .the moisture content is now roughly 5-10%.

Figure :-basic principle of paper machine

Introduction of Drying section:-

Paper dryer is an important equipment in paper making process. The dryer section is the last part of the paper machine which consist of series of steam drums. The most common way to evaporate water from the paper web is to use the latent heat of vaporization in steam. A steam-filled dryer is a cost effective method to transfer heat into the sheet. The moist paper web is rolled on these steam fed drums. Where the steam is used to evaporate the moisture from the web. The heat to the paper web is controlled by the steam pressure in the drum. The drying section consumes 70% of the total steam used in the paper mill. During grade transition, the drying section consumes energy without producing desired quality of paper.

1.4)- FACTORS AFFECTING ON THE MOISTURE IN THE PAPER :-

There are large number of variables that determine the moisture in the paper sheet,shown in fig1.4. To indicate the complexity of the problem some of them are listed below.

• Production speed- Affects the amount of steam needed, since high production also involves higher vaporization.

• Dry weight- A thick sheet is more difficult to dry than a thin sheet at the same production speed.

• Inlet moisture- The moisture content of the sheet after the press section is a

  disturbance variable that normally is unknown.

• Degree of Refining- The parameter naturally affects both the freeness and the ability to dry the sheet

• Air dew point- A high dew point inhibits effective evaporation.

• Dryer Fabric Condition- An old fabric can be clogged and give a higher evaporation resistance.

• Bulk- High bulk means that the water inside the web has a longer transport distance to the surface and ambient air.

• Web Tension- High web tension increases the heat transfer coefficient and the drying rate.

• Leakage air- The air from the machine room is cooler that the preheated supply air and therefore impair the drying condition

• Ply loading- In paperboard, different layers consist of different pulps, hence different physical properties. This influences the drying

FIGURE 1.4 factors affecting on the moisture in the paper during drying process

The name MATLAB stands for Matrix Laboratory. MATLAB was written originally to provide easy access to matrix software developed by the LINPACK (linear system package) and EISPACK (Eigen system package) projects. MATLAB is a high-performance language for technical computing. It integrates computation, visualization, and programming environment. Furthermore, MATLAB is a modern programming language environment: it has sophisticated data structures, contains built-in editing and debugging tools, and supports object-oriented programming. These factors make MATLAB an excellent tool for teaching and research.MATLAB has many advantages compared to conventional computer languages (e.g., C, FORTRAN) for solving

technical problems. MATLAB is an interactive system whose basic data element is an array that does not require dimensioning. The software package has been commercially available since 1984 and is now considered as a standard tool at most universities and industries worldwide. It has powerful built-in routines that enable a very wide variety of computations. It also has easy to use graphics commands that make the visualization of results immediately available. Specific applications are collected in packages referred to as toolbox. There are toolboxes for signal processing, symbolic computation, control theory, simulation, optimization, and several other fields of applied science and engineering.

Introduction of Matlab-

Introduction to MATLAB for Engineering Students" is a document for an introductory course in MATLAB R°1 and technical computing. It is used for freshmen classes at North-western University. This document is not a comprehensive introduction or a reference manual. Instead, it focuses on the specific features of MATLAB that are useful for engineering classes. The lab sessions are used with one main goal: to allow students to become familiar with computer software (e.g., MATLAB) to solve application problems. We assume that the students have no prior experience with MATLAB.The availability of technical computing environment such as MATLAB is now reshaping the role and applications of computer laboratory projects to involve students in more intense problem-solving experience. This availability also provides an opportunity to easily conduct numerical experiments and to tackle realistic and more complicated problems.

Modelling Of Steam dryer

Inlet paper web is to be dried to a desired moisture content using steam heated drums. To support and transport the paper web, it is covered with canvas or paper fabric. The canvas is also used to provide good thermal contact between the web and the cylinder. the drying section is enclosed within a drying hood to provide controlled ambient condition. The exhaust air from the hood removes

the evaporated water and preheated air is fed to the

Wth = RSLWth( w- w) -WA (7)

hood to maintain controlled environment for paper i o

drying process. This results in better heat

utilization and less variation in the paper quality. The basic configuration of a dryer shown in fig.

FIGURE:-input output stream of dryer

MODEL EQUATION The mathematical modeling of a dryer is based on mass/energy balance equation. In this case the assumptions are outer surface area and inner surface area of the dryer.

Outer surface area of cylinder is- DA=rL (1)

Corresponding outer surface area of web and

similarly mass balance for moisture- Wth

w wat w wat

w wat w wat

RSLWth(i MTin -o MTo ) -WA (8)

Heat energy balance on web –

W

W

SHo Wth=

W w w w w W

W w w w w W

WHDDA(DT-TOW)-WCHWA(TOW-TOC)+RSLWth

(SHi i Ti -o To SHO )- WAevH (9) heat balance on the cylinder-

DthDSHD =

SaSDh (DT-TOW)-r(2-)LDAh(DT-dT) (10)

heat balance on canvas-

C SH =W WC (T W-T C)-

canvas over cylinder th C C A

h O O

wA=(r+wth)L (2)

cA= (r+ wth +cth)L (3) Inner surface area of cylinder

Sa=(r-Dth)L (4)

The density of the web depends on its moisture content

w w w

w w w

i =265(1-MTi )+1000 MTi (5)

MASS balance on the web is-

= min -mout -WA (6) where

w

w

i o

i o

min= RSLDth w , M= w, mout=RSL Dtho

CACAh(TOC-DT)+WRSCthLSHC(T C-TOC) (11)

i

i

Amount of steam required is given by total heat demand divided by the latent heat of condensation of steam-

Relation between steam pressure and steam temperature

ST=100((P+SP)/105)0.25 (12)

Specific heat capacity of the web=

w) w

w) w

SHOW= (0.32-1.366asr+MTo / 1+MTo (13)

The evaporation rate,

=[WAh(Shu-hu)]/SHA+ ShuSHv (14) where air humidity is-

Shu = ,

Substituting these values in mass balance equation-

the exhaust air moisture given by soinien and karlosson

hu

22

Constant

22.04

Constant2

Add

2

Constant6

Divide1

560

Constant5 100

Constant7

Product1

Add1

Product

158

158

Constant1

Divide

1

m 5307

m1

2

Out1

(15)

From antoine equation the vapour partial pressures Pa AND Ps are-

ap=105(105.11564-)

SP= )

The heat of evaporation, Hev is the sum of the latent heat of vaporization and heat of sorption

evH= Vaph+Sh (16) where

2.74

2.72

2.7

2.68

heat amount

heat amount

2.66

2.64

2.62

2.6

2.58

2.56

32

Constant4

amount of heat required

Scope

Vaph = 505.3747(1-RT)

reduced temprature

0.354

+269.658(1-RT)

0.456

2.54

0 1 2 3 4 5 6 7 8 9 10

time

o

o

RT =T W/373.95

Sh=-0.10085R()MTW1.0585WET2

Relative humidity of air

FIGURE-AMOUNT OF STEAM REQUIRED(ms)

Fig; represents the simulation model and simulated result for relation between steam pressure and steam temperature

1 In1

70

Constant Add

(17)

u

uv

1.27e+005

1.27e+005

Divide

Heat transfer coefficient between air and web-

5

Constant1

10

Math Function

0.25

Constant2

Math Function1

100

Product

TS1 1

Out1

wa k B R nexp(k B NnMT W)+k B R nexp(k B

Constant3

WRS OW

WRS OW

h= 1 W S

1. W O

2. W S 4

nMT ) (18)

Heat transfer coefficient between drum and web-

Scope

DW =c exp(c MT w)+c exp(c M w) (19)

1.295

5

x 10

relatin between steam pressure and temprature

h 1 2 o 3 4 o

Fig :-represent the simulation model and simulated graph for a steam required ms depends upon heat demand latent heat of condensation of steam

1.29

steam temprature

steam temprature

1.285

1.28

1.275

1.27

0 1 2 3 4 5 6 7 8 9 10

steam pressure

5

x 10

1.295

The evaporation rate,

FIG-RELATION BETWEEN STEAM PRESSURE AND TEMP. TS

Fig:represents the simulation model and simulated result for the specific heat capacity

1.29

EVAPORATION RATE

EVAPORATION RATE

1.285

1.28

1.275

1.27

0 1 2 3 4 5 6 7 8 9 10

specific heat

FIG:- EVAPORATION RATE()

0.32

Constant

1.366

Constant1

2.33

Constant2

1.1

Constant3

1

Constant4

Product

Add

Add1

Divide

Scope

1

cpwo

-0.8394

-0.8394

cpwo1

Conclusion

This paper presents modeling and simulation of a paper drying machine. A SIMULINK model of the drying machine is developed considering the effcts of moisture,pressure and temperature. Modification of paper machine SIMULINK model is done to obtain the model of a drying process. The theoretically obtained characteristics of the paper drying experimentally verified for different ambient conditions.

1.295

1.29

specific heat output

specific heat output

1.285

1.28

1.275

5

x 10

Specific heat capacity of the web

Different drying system parameters were studied and it was concluded as a Matlab model. SIMULINK model was developed for a paper drying process. The performance of the system for different temperatures is analyzed. It was observed that a good matching can be achieved

Refrences

1.27

0 1 2 3 4 5 6 7 8 9 10

web moisture output

FIGURE -SPECIFIC HEAT CAPACITY SHOW

fig represents the simulated model and simulation result for evaporation rate which depends air humidity with respect to time

1. Senthilmurugan, tarun Mthur,

   Simplified Approach for Paper dryer Modeling TAPPI PaperCon09 Conference, May 31 June 3, 2009 St. Louis,

   2

   In2

   200

   Constant1

   320

   Product

   1 In1

   6600

   Constant

   Add

   Add1

   Divide

   Product1

   1

   lamda

   lamda1

   MO

   2.714

   2.714

   1. Johan Åkesson,Jenny Ekvall, parameter optimization of a paper machine model Department of Automatic Control Lund University BOX 118, 22100 Lund Network for Process Intelligence Mid Sweden University 89118 Örnsköldsvik

      Constant2

      Scope

   2. Akadmijas laukums, A mathematical model of paper dryingJ. Cepitis Institute of Mathematics, Latvian Academy of Sciences and

      University of Latvia, , Riga, LV1524,Version of record first published: 14 Oct 2010.

   3. Johan °Akesson,Ola Sl¨atteke, Modeling, Calibration and Control of a Paper Machine Dryer Section Department of Automatic Control, Faculty of Engineering, Lund University, Sweden ABB Ltd.,