Expert-Based-Computer Aided Design and Component Selection for Dust Collection Systems

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International Journal of Scientific Research in Environmental Sciences, 2(1), pp. 14-28, 2014

Available online at http://www.ijsrpub.com/ijsres

ISSN: 2322-4983; 2014 IJSRPUB

http://dx.doi.org/10.12983/ijsres-2014-p0014-0028

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Full Length Research Paper

Expert-Based-Computer Aided Design and Component Selection for Dust Collection

Systems

Ibrahim Medany1, Mostafa Shazly

2, Mahmoud G. El-Sherbiny

1*

1Mechanical Design and Production Engineering Depart., Cairo University, Giza, Egypt,

2Mechanical Eng. Depart., The British University in Egypt, Al-Shorouk City, Egypt,

*Corresponding Author: Tel: 00201006044616 Fax: 0020237746016, [email protected]

Received 30 October 2013; Accepted 27 December 2013

Abstract.Environmental regulations regarding industrial pollution are getting tougher to keep high air quality. The design of

proper system to meet specific requirements relays on selection of different filtration components. Components are available in

a wide range of designs to meet various requirements of air filtration level, quantity, and characteristics of the contaminants to

be removed. An expert system package for the selection of dust collectors components is developed. The developed package

utilizes database as well as knowledge base to aid the selection process based on practice and past experience. Industrial case

studies are demonstrated to test the developed package and compare its results against the current systems design. The

developed package in one case study estimated a minimum air flow rate of 60000 m3/hr, which is 30% higher than the

existing value and a static pressure drop due to ducts of about 1900 Pa which is 30 % lower than the current valueleading to improved air quality. In another case study the package results indicated the need to minimize the valueof air flow to be 2300 m3/hr, which is 50% lower than the current value and increase the external static pressure to

1700 Pa which is 70% higher than the existing design value leading to better filtration efficiency.

Keywords:Air Pollution, Dust Collection, Expert Systems, Design

1. INTRODUCTION

In every application, fine filtration is stronglydemanded, and air quality standards are much higherthan they were 50 years ago. The investment in gasfiltration of all kinds is about one sixth (16%) of the

total investment in filtration and its relatedseparations, worldwide. Air filtration devices remove

contaminants from an air or gas stream and are

available in a wide range of designs to meet various inair filtration requirements. Degree of removal,quantity and characteristics of the contaminant,conditions of the air or gas stream, fire safety, andexplosion control are among the factors that affect the

selection process.

Fig. 1:Elements of a Local Exhaust System


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For particulate contaminants, air cleaning devicesare divided into two basic groups: air filters and dustcollectors (Rajhans et al., 2004; Sutherland, 2008).Air filters are designed to remove low dustconcentrations of the magnitude found in atmospheric

air. They are typically used in ventilation, air-conditioning, and heating systems where dustconcentrations seldom exceed 0.025 grains per cubicmeters of air and are usually well below 0.0025 grainsper cubic meter. Industrial contaminant concentrations

will vary from less than 4 to 4000 grains per cubicmeter of air or gas. Therefore, dust collectors are, and

must be, capable of handling concentrations 100 to20,000 times greater than those for which air filtersare designed (Rajhans et al., 2004). In industrialventilation, only removing the larger dust particles

from the air stream may be necessary for cleanlinessof the structure, protection of mechanical equipment,and employee health (ASHRAE, 2008). Particles are

classified in three general categories (coarse, fine andultrafine) and are derived from dust, constructionactivities, printing, photocopying, manufacturingprocesses, smoking, combustion and some chemicalreactions in which vapors condense to form particles.

These can be categorized as dust, smoke, mist, fumeand condensates (Heinsohn et al., 2003).

The dust removal process can involve quite highsolid concentrations or low concentrations that willaffect the dust collector type. For example, at the

highest concentrations, the usual first step is acyclone, which removes suspended solids quite

efficiently, and collects them into an easily recyclablestate (Sutherland, 2008; Thomas et al., 1989).Generally, there are five types of dust collectors forparticulate contaminants, namely, Gravity Settling

Chamber, Dry Centrifugal Collectors, Wet Collectors,Electrostatic Precipitators, and Fabric Collectors(Rajhans et al., 2004; Sutherland, 2008).

Fig. 2:CAD Program Flow Chart

Local exhaust systems are employed to capture aircontaminants near their point of generation ordispersion. The local exhaust hood is the point ofentry into the exhaust system and is defined herein toinclude all suction openings regardless of theirphysical configuration. The primary function of the

hood is to create an air flow field that will effectivelycapture the contaminant and transport it into the hoodas shown in Fig 1. Hoods have wide range of physicalconfigurations but can be grouped into two general

categories: Enclosing and Exterior (Rajhans et al.,2004; Mahidol University, 2006; Jornitz, 2006).

To move air in ventilation or exhaust system,powered air moving device such as a fan or an ejectorare used. Selection of an air moving devices can be acomplex task and the designers are required to take

advantage of all available information fromengineering societies as well as from individualmanufacturers (Rajhans et al., 2004, Michigan, 1972).

The objective of the present work is to develop anexpert system package which can be implemented in a


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user friendly Computer Aided Design (CAD) programfor the selection of dust collectors and theircomponents. Dust collection systems are usuallydesigned as a construction from individualcomponents such as cyclones, filters, ducts, fans and

other joining elements for the severe loads generatedfrom industrial processes where the air or gas to becleaned originates in local exhaust systems or processstack gas effluents.

Expert systems have been used extensively

over wide range of applications ranging from

medical and industrial to business applications.

Expert systems have the advantages of their

consistency, completeness, reproducibility, and

efficiency. However, they cannot adapt to

changing environments, unless their knowledge

base is changed, and when any errors occur in the

knowledge base, will lead to wrong decisions

(Arlington, 1983; Giarratano and Riley, 2004;

Eronen and Zitting, 2001; Gamal et al., 2010;

Beanlands, 1994; Bohanec and Rajkovic, 1990).

The expert system's reasoner operates over

well-defined domain rules. These rules can be

thought of as IF-THEN statements. Once the IF

part of the statement is satisfied the THEN part is

computed which can introduce additionalinformation (Stefik et al., 1982; Ratajkosk et al.,

2001; Clancey, 1983, Rahim and Ahmad, 2006).

It also manipulates the knowledge base which can

recursively cause more rules to be applied

causing what is called as forward chaining

(Eronen and Zitting, 2001).

The objective of the present work is to develop

an expert-based-computer aided design and

component selection for dust collection systems.

The developed system will make use of the

current design approaches in dust collectionsystem and collected data from experts and past

studies that will aid in the selection criteria and

decision making.

Fig. 3:Main Screen

2. COMPUTER AIDED DESIGN OF DUST

COLLECTION SYSTEM

Visual Basic program has been developed to assist in

the design of dust collection system. The program issubdivided into eight main parts as shown in Fig 2.The developed package allows the user either to build

a new system from scratch, edit or adopt previouslydesigned systems as shown in Fig 3. The data used in

both cases are kept in the expert system memory assuch that the user has the ability to make decisions to

achieve better design for the dust collection system.

2.1. Application and Dust Types

The first step in the design process is to choose the

application type and the information about the dust tobe collected. The interface screen for this purpose


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contains three sections: Application Type, Dust Typeand Dispersion Type as shown in Figs 4 and 5. Thepackage allows the user to select the dust and particletypes. If explosive and sticky dusts are to be removedthey must be considered in the design process. The

user in this case has to check or uncheck theappropriate check boxes in the window. Finally, thepackage allows the user to select the Dispersion Typewhich includes released with practically no velocityinto quiet air, active generation into zone of rapid air

motion etc. In all cases the built-in expert systempresents application examples and recommended

capture velocity. The package and the built-in expertsystem guide the users throughout the selectionprocess. For example, a warning message appearswhen a non-recommended duct velocity is used, as

shown in Fig 6. Other examples include the frequencyof the same application type previously used,concentration dust load, duct velocities (main andsub), as illustrated in Fig 7.

2.2. Dust Collector Selection

Based on the previously selected application and dusttype, the built-in knowledge base recommends thetype of dust collector to be used as shown in Fig 8.

The package guides the user to determine thefrequently used systems through on Often and

Seldom usage keys.

2.3. System Design and Local Hoods

The interface of System Design and Local Hoodsconsists of No. of Extraction Points, SystemHood and Duct Design System as shown in Fig9.First, the user must feed in the number of extractionpoints of the sources of emission to be removed. Then

click on Design System Button to draw the singleline diagram of dust collection system includingLocal Hoods, Branch Ducts, Main Duct, DustCollector, Fan, The Duct Connecting DustCollector and Fan and Fan Outlet Duct Chimney.

These input data will be used in Hood calculationsand Duct design. Hood calculations data include hoodtype, air flow, hood static pressure, and branchpressure loss and duct.Duct design system includesduct between First Hood and Dust Collector, duct

between Dust Collector and Fan, and Fan outletduct as shown in Fig 9.

2.4.Hood and Duct DesignThe package allows the user to select the hood

type according to source and direction of

emission. This includes, for example, slot and

flanged slot hoods, and other types of hoods as

shown in Figs 10 and 11.

First, the interface allows the user to select

hoods successively and then specify the hood

type as shown in Fig 10.The user then feeds in

the parameters in two steps as shown in Fig 10.

The first step is to specify input parameters for

selected hood (hood width, hood length, face

diameter, and taper angle of hood shape) based on

the application and the geometry of the pickup

point. The second step is to input data for

pressure losses (straight duct length from hood to

branch including flexible or rigid ducts, duct

material, fitting losses coefficients as shown inFig 12). The results of these steps are the Air

Flow, Hood Static Pressure and Duct Diameter as

illustrated inFig 13. Fig 14 shows an example of

the expert system; applications where a warning

message appears if calculated slot velocity is

greater than 10 m/s.The process of hood design is followed by duct

design. The input in this case includes ductingparameters between Hood 1 and Dust Collector, Ductbetween Fan and Dust collector and Duct of Fanout/stack/chimney. This also includes the duct lengthand fitting loss in the duct branch as shown in Figs

15-17. The results of duct design process are ductdiameters; air flow in the branch and main ducts, andthe pressure losses.


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Fig. 4: Flow Chart of Dust and Application Type

Fig. 5: Dust and Application Type


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Fig. 6: Warning Message for the Duct Velocity

Fig. 7: Dust and Application Type

Fig. 8: Dust Collector Parameters


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Fig. 9: System Design and Local Hoods

Fig. 10:Hood Parameters


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2.5. System Results and Report

The design of the complete system is reported by thepackage in the form of design report that includes all

the necessary information to install the dust collectionsystem. This includes the External Static Pressure(Pa.) at the ultimate operating conditions and Total

Air Flow Rate (Q, m3/hr) as shown in Fig 18. If the

external static pressure exceeds 3000 Pa, the system

should be redesigned by increasing the number of theextraction points of the design and a two fans solutionmay be more appropriate to minimize the fan and dustcollector size. The fan selection process requires theTotal Static Pressure and Total Air Flow Rate.

This process requires the knowledge of thepressure drop across the filters. This informationvaries from supplier to another and must be obtainedfor the filters to be installed in the designed system.

Fig. 11: Hood Parameters- Other Hood Types

3. RESULTS AND DISCUSSIONS

The above developed package is used to re-designexisting dust collection systems for Paper-Winder

Machine and a Fertilizers Crusher Room. The purposeof this section is to demonstrate some examples ofindustrial applications where the developed package

can show its effectiveness. The developed packagecan save time and enable decisions to be made basedon past experiences and practices.

3.1. Paper-Winder Machine Case Study

Significant amount of dust are produced duringreeling, unwinding, and slitting of paper rolls. This

dust causes many problems to printing machines andcan impair the printing quality. Moreover, it affectsworking environment, causes health problems, andincreases fire risk. Working with coated or calendared

paper rolls decreases the amount of dust but at highercost.

The winder area is usually cleaned with

pressurized air causing clouds of fiber dust to rise inthe air and therefore, employees and operators needrespiratory masks in order to survive the work place

environment.


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Fig. 12: Hood Parameters-Fitting Coefficients (Elbow)

Fig. 13: Hood Parameters - Complete Calculations


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Fig. 14: Slot Velocity Warning Message

Table 1:Dust Collection System Report for Paper-Winder Machine

Application Name: Winder of Paper Machine Version 1

Date: 23/12/2011

Main Application: Coal, Mining and Power Plant

Sub Application: De-dusting, air cleaning

Concentration Dust Load (gr/m3): Heavy: 12 and up

Explosive Dust or any spark from application: Yes Dust Sticky: No

Dust Type: Average Industrial DustMain Duct Velocity (m/s): 20 Branch Duct Velocity (m/s): 20

Particle Type: Paper Tissue Dust

Dispersion Type: Released at high velocity into zone of very rapid air motion

Capture Velocity (m/s): 2.5

Dust Collector Type: Venturi Collector (Wet Collector)

External Static Pressure (Pa.): 1900

Total Air Flow (m3/h): 60,000

No. of Extraction Points: 15

The existing dust collection system uses VentureWet Scrubber consisting of 15 extraction points withfan capacity 45000 m

3/hr having external static

pressure 2000 Pa. The existing dust collectors were

expected to reduce emissions to air but they were notefficient enough. There were also problems with dust,particularly during the winding process. Afterwinding, some of the dust was trapped between papersheets and some accumulated on the machine frame

and fell back onto the paper. The present package wasused to re-design the current collection system. The

summary for the input data and results are shown inTable 1, which contains the information about theprocess and the pickup points and preferred pickupvelocities. The results showed that the minimum air

flow rate is 60000 m3/hr, which is 30% higher than the

existing value. Also the static pressure drop due toducts is 1900 Pa which is 30 % lower than the currentvalue. These results indicate that the system needs

higher capacity of air flow at almost the same externalstatic pressure. These results are different from theexisting system design because the computed captureand hood face velocities (based on the knowledgebase built in the expert system) were higher than the

current values of the existing system. Also thedistance from hood face to the farthest source is

reduced to achieve better capture of dust and higherefficiency. As a result of the modified design, the airquality around the machines and working area isexpected to be better.


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Fig. 15: Duct System Databetween Hood 1 and Dust CollectorComplete Calculations

Fig. 16: Duct System DataDuct between Fan and Dust CollectorComplete Calculations


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Fig. 17: Duct System ParametersDuct between Fan and Dust CollectorComplete Calculations

Fig. 18: System Results


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Table 2:Dust Collection System Report for Crusher Room

Application Name: Crusher Room of Fertilizer Version 2

Date: 24/12/2011

Main Application: Chemicals

Sub Application: Crushing, grinding

Concentration Dust Load (gr/m ): Moderate: 5 to 12Explosive Dust or any spark from application: No Dust Sticky: No

Dust Type: Average Industrial Dust

Main Duct Velocity (m/s): 20 Branch Duct Velocity (m/s): 20

Particle Type: Fertilizer

Dispersion Type: Released at low velocity into moderately still air.

Capture Velocity (m/s): 0.5

Dust Collector Type: Intermittent-Shaker Collector (Fabric Collector)

External Static Pressure (Pa.): 1700

Total Air Flow (m /h): 2300

No. of Extraction Points: 8

3.2. Fertilizer Crusher Room Case Study

An Agricultural Fertilizer Company has anUnderground Crusher Room. The Crusher Room

consists of a Crusher, Screw Conveyors, BucketElevator, Hooper and Vibrator Screen. Due to the

crushing process, the room is filled with foggy airwith high dust concentration; and as a result the dustleaves the room to other working areas of production.The existing installed dust collection system servicingthe crusher room area consists of eight extractionpoints, Intermittent-Shaker Fabric Collector, a fanwith a capacity of 4400 m3/hr and an external staticpressure 1000 Pa. The dust collection systemefficiency is 85 % approximately and was satisfactoryfor the client. The computer aided design programwas used to check the design of this particular dustcollection system. The input data and results are

summarized in Table 2. The results indicated the needto minimize the value of air flow to be 2300 m

3/hr,

which is 50% lower than the current value. Also theexternal static pressure due to duct is 1700 Pa which is70 % higher than the existing design value. Theseresults are different from the existing system design

because the capture velocity was lower than theexisting system. The knowledge base built in theexpert system attempted to minimize the collection ofproduct and minimize the size of fan and motorthereby reducing the power consumption and runningcost.

4 CONCLUSIONS

The present work introduced a proceducer fordesigning Dust Collection System, using an expertsystem based package for the selection of dustcollectors and their components. The developedpackage utilizes database as well as knowledge baseto aid the selection process. Expert data form previous

experiences and practices are introduced to help in theselection of the components of the Dust Collectionsystem, leading to maximizing the efficency andminimizing the cost of maintenance. The developedexpert based program can save time and enable

decisions to be made based on past experiences andpractices.

The examples considered in this study showed thatthe proposed designs suggested by the packagesupport by the expert system is different from the

current ones. The causes of these differences betweenthe existing designs and the new designs are

illustrated in two main points:Air Flow quantity andStatic Pressure value. The distance from hood face to

farthest point of emission sources should be minimum(near or close) and the designer must consider otherhood types parameters, where the required air flow ofsuction is calculated rather than by the using thetraditional equation (Q=V(volume) x A(area)) of

hood. The static pressure loss of exhaust hood,flexible ducts , duct surface finish must also beconsidered in the design.


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Ibrahim Medany is currently a Project Manager for HVAC and Filtration (Dust Collection) Projects at

Hammam Industries & Co. Company. He received his B.Sc. in Mechanical Production and Printing

Technology from Akhbar Al-Youm Academy for Engineering, Printing and Press Technology in Egypt

in 2006 and his M.Sc. in Mechanical Design and Production Engineering from Faculty of Engineering

Cairo University in 2012.

Dr. Mostafa Shazly is an Associate Professor at the Mechanical Engineering Department, Associate

Director for the Centre of Advanced Materials, the British University in Egypt. He received his B.Sc.and M.Sc. in Mechanical Design and Production Engineering from Faculty of Engineering, Cairo

University in 1996 and 1999, respectively. He received his Ph.D. in Mechanical Engineering in 2005

from Case School of Engineering, Case Western Reserve University, OH, USA.

Prof. Mahmoud G. El-Sherbiny received the B.Sc. degree in Mechanical Engineering with honors from

Cairo University, Egypt, in 1968, the M.S. from Cairo University on a cooperation program with the

University of Denmark at Copenhagen in 1972, and Ph.D. degree from the Department of Aeronautical

and Mechanical Engineering at the University of Salford, U.K, in 1975.

He joined the department of Mechanical Design and Production Engineering at Cairo University since

1968 and promoted to Professor of Machine Design and Engineering Tribology in 1986. He is the

founder of the Egyptian Society of Tribology (EGTRIB) in 1987, Tribology and Spare Parts Center

(TSPC) at Cairo University in 1988, The Scientific journal of the Egyptian Society of Tribology in

2002, and The Arab Federation for Metrology (AFM) in 2007. He was appointed as Vice Dean for

Curriculum and Students affairs in 1994, Dean of Engineering at Cairo University 1995-2001, andPresident of the National Institute of Standards 2005-2006.

He published 56 reviewed articles in world known journals and holds 11 registered patents.

Documents

Expert-Based-Computer Aided Design and Component Selection for Dust Collection Systems