Handbook of food processing equipment 2edition

PFDs, which are indispensable for material and energy balances, and preliminarysizing of process equipment.Some important aspects of food plant design are discussed in the last part of t

Series Editor: Gustavo V Barbosa-Cánovas

Food Engineering Series

Second Edition

Food Engineering Series

Series Editor

Gustavo V Barbosa-Ca´novas, Washington State University, USA

Advisory Board

Jose´ Miguel Aguilera, Catholic University, Chile

Richard W Hartel, University of Wisconsin, USA

Albert Ibarz, University of Lleida, Spain

Jozef Kokini, Purdue University, USA

Michael McCarthy, University of California, USA

Keshavan Niranjan, University of Reading, United KingdomMicha Peleg, University of Massachusetts, USA

Shafiur Rahman, Sultan Qaboos University, Oman

M Anandha Rao, Cornell University, USA

Yrj€o Roos, University College Cork, Ireland

Jorge Welti-Chanes, Monterrey Institute of Technology, Mexico

providing exceptional texts in areas that are necessary for the understanding anddevelopment of this constantly evolving discipline The titles are primarilyreference-oriented, targeted to a wide audience including food, mechanical,chemical, and electrical engineers, as well as food scientists and technologistsworking in the food industry, academia, regulatory industry, or in the design offood manufacturing plants or specialized equipment.

More information about this series at http://www.springer.com/series/5996

George Saravacos • Athanasios E Kostaropoulos

Handbook of Food

Processing Equipment

Second Edition

21100 Nauplion, Greece Athens, Greece

ISSN 1571-0297

Food Engineering Series

ISBN 978-3-319-25018-2 ISBN 978-3-319-25020-5 (eBook)

DOI 10.1007/978-3-319-25020-5

Library of Congress Control Number: 2015952650

Springer Cham Heidelberg New York Dordrecht London

© Springer International Publishing Switzerland 2016

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The use of general descriptive names, registered names, trademarks, service marks, etc in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made.

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1 Design of Food Processes and Food Processing Plants 1

1.1 Introduction 1

1.2 Overview of Chemical Process and Plant Design 2

1.2.1 Process Flow Sheets 3

1.2.2 Types of Process Designs 3

1.2.3 Material and Energy Balances 4

1.2.4 Design of Equipment 5

1.2.5 Plant Layout and Buildings 6

1.2.6 Economic Analysis in Process/Plant Design 7

1.2.7 Manufacturing Cost and Profitability 11

1.2.8 Computer-Aided Process/Plant Design 14

1.3 Design of Food Processes 15

1.3.1 Unit Operations in Food Processing 19

1.3.2 Food Process Flow Sheets 22

1.3.3 Material and Energy Balances 23

1.3.4 Computer-Aided Food Process Design 28

1.4 Food Plant Design 28

1.4.1 Elements of Food Plant Design 29

1.4.2 Good Manufacturing Practices 36

1.4.3 Food Plant Economics 38

References 47

2 Design and Selection of Food Processing Equipment 51

2.1 Introduction 51

2.2 Sizing and Costing of Equipment 52

2.3 Materials of Construction 54

2.3.1 Metals 55

2.3.2 Plastics–Rubber 59

2.3.3 Glass–Ceramics 60

2.3.4 Wood 60

v

2.4 Fabrication of Equipment 61

2.4.1 Strength of Construction 61

2.4.2 Fabrication and Installation of Equipment 64

2.5 Hygienic Design of Food Processing Equipment 66

2.5.1 Hygienic Standards and Regulations 66

2.5.2 Cleaning of Food Equipment 69

2.6 Selection of Food Processing Equipment 72

2.6.1 Selection of Equipment 72

2.6.2 Testing of Equipment 78

2.6.3 Equipment Specifications 79

2.7 Directories of Equipment 82

2.7.1 Directories of Food Equipment 82

2.7.2 Exhibitions of Food Equipment 83

References 83

3 Mechanical Transport and Storage Equipment 87

3.1 Introduction 87

3.2 Mechanical Transport Equipment 88

3.2.1 Fluid Food Transport Equipment 88

3.2.2 Pneumatic and Hydraulic Transport Equipment 108

3.2.3 Mechanical Conveyors 112

3.3 Food Storage Equipment 126

3.3.1 Introduction 126

3.3.2 Storage of Solids 126

3.3.3 Storage of Liquids 138

References 146

4 Mechanical Processing Equipment 149

4.1 Introduction 149

4.2 Size Reduction 149

4.2.1 Introduction 149

4.2.2 Cutting 153

4.2.3 Crushing and Grinding Equipment 165

4.3 Size Enlargement 186

4.3.1 Introduction 186

4.3.2 Agglomeration Equipment 189

4.3.3 Selection of Agglomeration Equipment 207

4.4 Homogenization 207

4.4.1 Introduction 207

4.4.2 Homogenization Equipment 208

4.5 Mixing and Forming Equipment 214

4.5.1 Introduction 214

4.5.2 Fluid Mixing Equipment 214

4.5.3 Paste and Dough Mixing Equipment 219

4.5.4 Extrusion and Forming Equipment 220

4.5.5 Butter and Cheese Processing Equipment 226

4.5.6 Solid Mixing and Encrusting Equipment 227

References 230

5 Mechanical Separation Equipment 233

5.1 Introduction 233

5.2 Classification Operations 235

5.2.1 Grading 236

5.2.2 Sorting 237

5.3 Solid/Solid Separations 241

5.3.1 Screening 241

5.3.2 Fluid Classification 247

5.4 Solid/Liquid Separators 251

5.4.1 Screens 251

5.4.2 Sedimentation Equipment 251

5.4.3 Industrial Filters 252

5.4.4 Centrifuges 258

5.4.5 Mechanical Expression 263

5.5 Solid/Air Separators 270

5.5.1 Cyclone Separators 270

5.5.2 Bag Filters 272

5.5.3 Air Filters 274

5.5.4 Electrical Filters 275

5.5.5 Wet Scrubbers 276

5.6 Removal of Food-Related Parts 276

5.6.1 General Aspects 276

5.6.2 Removal of Undesired Own Parts 277

5.6.3 Removal of Desired Parts 287

5.6.4 Food Cleaning Operations 287

References 290

6 Heat Transfer Equipment 293

6.1 Introduction 293

6.2 Heat Transfer Coefficients 293

6.3 Empirical Correlations of (h) 296

6.3.1 General Correlations 296

6.3.2 Simplified Equations for Air and Water 298

6.3.3 Heat Transfer Factor 299

6.4 Heat Exchangers 300

6.4.1 Overall Heat Transfer Coefficients 300

6.4.2 Fouling of Heat Exchangers 302

6.4.3 Residence Time Distribution 303

6.4.4 Tubular Heat Exchangers 304

6.4.5 Plate Heat Exchangers 306

6.4.6 Agitated Kettles 310

6.4.7 Scraped Surface Heat Exchangers 312

6.4.8 Direct Heat Exchangers 314

6.4.9 Baking and Roasting Ovens 315

6.4.10 Fryers 318

6.4.11 Radiation Heaters 319

6.4.12 Heat Generation Processes 321

6.4.13 Hygienic Considerations 324

References 329

7 Food Evaporation Equipment 331

7.1 Introduction 331

7.2 Heat Transfer in Evaporation 332

7.2.1 Physical Properties 332

7.2.2 Heat Transfer Coefficients 333

7.2.3 Fouling in Evaporators 333

7.2.4 Heat Transfer in Film Evaporators 334

7.2.5 Falling Film Evaporation of Fruit Juices 338

7.3 Food Quality Considerations 340

7.4 Food Evaporators 340

7.4.1 Material and Energy Balances 340

7.4.2 Long Residence-Time Evaporators 341

7.4.3 Short Residence-Time Evaporators 344

7.5 Energy-Saving Evaporation Systems 348

7.5.1 Multiple-Effect Evaporators 348

7.5.2 Vapor Recompression Evaporators 351

7.5.3 Heat Pump Evaporators 353

7.5.4 Combined Reverse Osmosis/Evaporation 355

7.5.5 Water Desalination 355

7.5.6 Waste-Heat Evaporators 355

7.6 Evaporator Components 356

7.6.1 Evaporator Bodies 356

7.6.2 Vapor/Liquid Separators 357

7.6.3 Condensers 358

7.6.4 Vacuum Systems 359

7.6.5 Evaporator Control 360

7.6.6 Testing of Evaporators 360

7.6.7 Hygienic Considerations 361

References 364

8 Food Dehydration Equipment 367

8.1 Introduction 367

8.2 Principles of Drying 368

8.2.1 Psychrometric Calculations 368

8.2.2 Drying Rates 370

8.2.3 Food Dehydration Technology 374

8.3 Design and Selection of Food Dryers 375

8.3.1 Heat and Mass Transfer 376

8.3.2 Modeling and Simulation of Dryers 379

8.3.3 Design of Industrial Dryers 381

8.3.4 Selection of Industrial Dryers 382

8.3.5 Commercial Food Drying Equipment 383

8.3.6 Special Food Dryers 405

8.3.7 Hygienic and Safety Considerations 409

8.4 Energy and Cost Considerations of Drying 410

8.4.1 Heat Sources for Drying 410

8.4.2 Heat Recovery 411

8.4.3 Energy-Efficient Dryers 412

8.4.4 Cost Considerations 413

References 415

9 Refrigeration and Freezing Equipment 421

9.1 Introduction 421

9.2 Refrigeration Equipment 422

9.2.1 Refrigeration Cycles 422

9.2.2 Compressors 427

9.2.3 Evaporators 433

9.2.4 Condensers 443

9.2.5 Capacity Control 445

9.3 Refrigerants 446

9.3.1 Introduction 446

9.3.2 Natural Refrigerants 452

9.3.3 Fluorocarbon and Blend Refrigerants 453

9.4 Lubricants 455

9.4.1 Main Types of Lubricants 455

9.4.2 Function of Lubrication 456

9.4.3 Requirements for Good Lubrication 456

9.4.4 Choice of Refrigerant Lubricants 458

9.4.5 Additives 459

9.5 Cooling of Foods 459

9.5.1 Chilling 459

9.5.2 Cooling Equipment 462

9.6 Freezing of Food 468

9.6.1 Freezing 468

9.6.2 Freezing Equipment 474

9.6.3 Thawing Equipment 482

9.7 Cold Storage 485

9.7.1 General Aspects 485

9.7.2 Reduction of Weight Loss 489

9.8 Ice Manufacturing 493

References 499

10 Thermal Processing Equipment 503

10.1 Introduction 503

10.2 Kinetics of Thermal Inactivation 504

10.2.1 Inactivation of Microorganisms and Enzymes 504

10.2.2 Thermal Damage to Food Components 507

10.3 Heat Transfer Considerations 507

10.3.1 General Aspects 507

10.3.2 Unsteady-State Heat Transfer 508

10.4 Thermal Process Calculations 511

10.4.1 In-container Sterilization 511

10.4.2 Continuous Flow Thermal Processes 514

10.5 Thermal Processing Equipment 517

10.5.1 General Aspects 517

10.5.2 In-container Sterilizers 517

10.5.3 Continuous Flow (UHT) Sterilizers 535

10.5.4 Thermal Pasteurizers 539

10.5.5 Thermal Blanchers 543

10.5.6 Hygienic Considerations 544

References 546

11 Mass Transfer Equipment 549

11.1 Introduction 549

11.2 Distillation Equipment 551

11.2.1 Vapor/Liquid Equilibria 551

11.2.2 Determination of Equilibrium Stages 557

11.2.3 Food Distillation Equipment 564

11.3 Solvent Extraction/Leaching Equipment 570

11.3.1 Liquid/Liquid and Liquid/Solid Equilibria 570

11.3.2 Determination of Equilibrium Stages 573

11.3.3 Mass Transfer Considerations 574

11.3.4 Food Extraction and Leaching Equipment 576

11.3.5 Curing 579

11.4 Gas/Liquid Absorption Equipment 585

11.4.1 Gas/Liquid Equilibria 586

11.4.2 Determination of Equilibrium Stages 587

11.4.3 Gas Absorption and Stripping Equipment 590

11.5 Adsorption and Ion Exchange Equipment 591

11.5.1 Adsorption Equilibria and Mass Transfer 592

11.5.2 Adsorption Equipment 593

11.5.3 Ion Exchange Equipment 594

11.5.4 Food Applications 595

11.6 Crystallization from Solution Equipment 597

11.6.1 Solubility Considerations 597

11.6.2 Nucleation and Mass Transfer 598

11.6.3 Industrial Crystallizers 599

References 602

12 Equipment for Novel Food Processes 605

12.1 Introduction 605

12.2 Membrane Separation Equipment 606

12.2.1 Mass Transfer Considerations 606

12.2.2 Membranes and Membrane Modules 608

12.2.3 Membrane Separation Systems 609

12.2.4 Reverse Osmosis and Nanofiltration 611

12.2.5 Ultrafiltration 613

12.2.6 Microfiltration 616

12.2.7 Pervaporation 618

12.2.8 Electrodialysis 620

12.3 SCF Extraction 621

12.3.1 Supercritical Fluids 621

12.3.2 SCF Extraction Processes and Equipment 622

12.3.3 SCF Extraction in Food Processing 623

12.4 Crystallization from Melt 624

12.4.1 Freeze Concentration 624

12.4.2 Fat Fractionation 626

12.5 Nonthermal Food Preservation 627

12.5.1 Food Irradiation 628

12.5.2 High-Pressure Processing 634

12.5.3 Pulsed Electric Field Processing 635

12.5.4 Nanotechnology 636

12.6 Robotics 637

References 641

13 Food Packaging Equipment 645

13.1 Introduction 645

13.1.1 General Aspects 645

13.1.2 Packaging Characteristics 647

13.1.3 Packages and Packaging Materials 651

13.2 Preparation of Food Containers 657

13.2.1 Unscrambling 657

13.2.2 Fabrication and Forming of Packages 658

13.3 Filling Equipment 666

13.3.1 General Characteristics 666

13.3.2 Dosing 670

13.3.3 Product Transfer Systems 672

13.3.4 Valves 674

13.3.5 Weighing 676

13.4 Closing Equipment 679

13.4.1 Closing of Food Packages 679

13.4.2 Glass Closures 680

13.4.3 Closing of Metallic Containers 681

13.4.4 Closing of Plastic Packages 682

13.4.5 Closing of Cartons and Cardboard 683

13.5 Aseptic Packaging 683

13.6 Group Packaging 688

13.6.1 Grouping of Packages 688

13.6.2 Wrapping 688

13.6.3 Palletizing 691

13.7 Cleaning of Packaging Media 693

References 694

Appendix A: Notation and Conversion of Units 697

Appendix B: Selected Thermophysical Properties 703

Appendix C: Control of Food Processing Equipment 709

Appendix D: Food Plant Utilities 711

Appendix E: Manufacturers and Suppliers of Food Equipment 717

Index 757

processing plant, including the processing/control equipment, the utilities, the plantbuildings, and the waste treatment units The two terms are used interchangeably inthe technical literature Both process and plant design are basic parts of feasibilityand implementation studies of an industrial project, such as a food processing plant.The necessary phases for realizing an industrial project include the preliminarystudy, the feasibility study, and the implementation of the project The feasibilitystudy includes most of the technical and economic information obtained in processand plant design The implementation phase involves detailed engineering, con-struction, supply of equipment, and plant erection and start-up.

The development of food process/plant design is based on the principles of foodscience and technology, chemical engineering, and on the practical experience offood engineers, chemical engineers, and food technologists In plant design, theexperience and developments in other technical fields, such as materials science,mechanical engineering, and management, should also be considered

Since the literature on research and development and applications of foodprocess/plant design is limited, it is necessary to review the basics of chemicalprocess/plant design, which will be applied critically in the various chapters ofthis book

The unique requirements of design of food processes, food plants, and foodprocessing equipment are considered in more detail in this chapter The numerousfood processing operations are classified in an analogous manner with theestablished unit operations of chemical engineering Food processes are represented

by the familiar process block diagrams (PBDs) and the process flow diagrams

© Springer International Publishing Switzerland 2016

G Saravacos, A.E Kostaropoulos, Handbook of Food Processing Equipment,

Food Engineering Series, DOI 10.1007/978-3-319-25020-5_1

1

(PFDs), which are indispensable for material and energy balances, and preliminarysizing of process equipment.

Some important aspects of food plant design are discussed in the last part of thischapter, emphasizing the need for an integrated approach of hygienic design, foodproduct quality and safety, and cost-effectiveness

The general aspects of design and selection of food processing equipment are

concerning the effectiveness of plant design toward this goal

Chemical process and plant design have been developed mainly in the chemical,petrochemical, and petroleum industries, where very large amounts of materials,usually gases and liquids, are processed continuously into a rather small number ofproducts The design, operation, and control of these large plants have beenadvanced in recent years by the use of computers and the availability of databanks of the physical properties of gases and liquids

Modern process and plant design must reduce raw material costs, capital ment, plant energy consumption, inventory in the plant, and the amount of pollut-ants generated The new plants need improved process flexibility, safety, andcontrol technology Process design should be based more on computer modeling,

Process design includes the synthesis, analysis, evaluation, and optimization ofprocess alternatives Chemical process design is essential in the design of newplants, in the modification or expansion of an existing plant, in the production of anew product, and in the simulation and control of an operating plant The impor-tance of design is demonstrated by the fact that during the process design (about

2 % of the total project cost), decisions are made that will fix the major portion of

Econom-ics plays a very important role in any design of chemical processes and chemicalplants

The engineering part of a design project involves basically the development ofthe process flow sheet, the material and energy balances, and the sizing of theprocess equipment In addition, the following essential components of the processplant should be considered: plant location, utilities, plant layout, buildings (archi-tectural and civil engineering), plant operation and control, health and safety, wastedisposal, personnel, and legal requirements (restrictions)

Continuous processes are generally preferred over batch processes in the largechemical, petrochemical, and petroleum industries, because they are less expensive

in both equipment and operating costs Batch processes may prove more ical for smaller plants and for food, pharmaceutical, and specialty products Batch

econom-processes are also preferred when little information is available, when process/products have relatively short life cycles, or when a variety of products areproduced in small quantities.

Although considerable progress has been made on the application of modelingand computers to the design of chemical processes and plants, design continues torely largely on the practical experience and the “art” of design engineers In thedesign process, a balance of many technical, operational, and economic factors

1986)

Process flow sheets represent graphically the required process equipment and theflow of materials and utilities in an industrial plant The simplest diagram of a

diagram (PFD), which is used in the preliminary design of process equipment

indicates the details of piping and process instrumentation of the plant The PFD,PID, and PCD are used in the detailed process/plant design

The analysis, selection, and optimization of the process flow sheets (PFDs) areessential in large-scale processing plants, where process economics is very impor-tant Combinations of PFD and analytical tables of materials, energy, and laborrequirements in each stage are useful, especially when performing an economic

recently replaced the intuitive flow sheet development Numerical solutions andcomputer techniques are used to solve complex flow sheet problems

In more complex plant designs, techniques of operations research are used TheGantt and the PERT diagrams enable the time scheduling and realization of a

There are several types of process and plant design, ranging from simple tions of low-accuracy to high-accuracy detailed designs Simple and preliminaryestimates are employed to obtain an approximate idea of the required equipmentand investment, while a detailed design with drawings and specifications is used forthe construction, operation, and control of the processing plant

Table 1.1 shows five types of process estimates and designs of increasing

on almost complete data before preparing the drawings and specifications Thedetailed design or the contractor’s estimate is based on complete data, engineeringdrawings, and specifications for equipment and plant site The accuracy of theestimation varies from 40 % (ratio method) to 5 % (detailed design)

estimates The most common cost estimates are the preliminary and detaileddesigns with accuracies of 15 and 5 %, respectively The cost of preparing the

indicative and it depends on the investment, being substantially lower for large

for preparing the preliminary and detailed process designs varies with the plexity and size of the project, being typically about 8 and 12 months, respectively

The design of process equipment and plant utilities is based primarily on materialand energy (heat) balances, which are usually calculated on the PBD Someapproximations are necessary to reduce and simplify the time-consuming calcula-tions, especially for large, complex processing plants, e.g., feed enters the variousunits at saturation temperature

Two general methods of calculations are usually applied: the modular and the

types of equations are solved separately: (1) the connectivity equations of the units

of the flow sheet, (2) the transport rate and equilibrium equations for each unit, and(3) the equations for the physical, thermodynamic, equilibrium, and transportproperties In the equation-oriented mode, all of the process equations are combined(material/energy balances, thermodynamic and transport, equipment performance,

Table 1.1 Types of chemical process design

kinetics, and physical property) into a large, sparse equation set, which is solvedsimultaneously, usually applying a Newton-type equation solver.

The models for material/energy balances are simplified into linear equations byassuming ideal solutions and saturated liquid or vapor streams The calculations ofmaterial and energy balances are usually made by hand or by PC computers, usingsimple Excel spreadsheets or data tables For complex, nonideal processes, rigorousmethods are employed, requiring special computer algorithms The physical andtransport properties of the materials are obtained from standard books or databases

In preliminary estimations, the approximate size of the process equipment is neededfor economic evaluation and subsequent detailed calculations for the processingplant Material and energy balances, based on the process flow sheet, are used as abasis for the estimation of the various units A fixed feed rate is assumed (kg/h ortons/h) and all of the materials and heat flows in each unit are calculated

Transport rate equations and equilibrium relationships are used, includingmechanical transfer (pumping), heat transfer, mass transfer, reaction rate, andphase equilibria (vapor/liquid, liquid/liquid, and fluid/solid)

The physical and engineering properties of the materials being processed areneeded under the actual conditions of concentration, temperature, and pressure.Data of physical and transport properties are obtained from standard literature texts

Transport properties and heat and mass transfer coefficients are difficult topredict theoretically, and experimental or empirical values, appropriate for thespecific equipment and process conditions, are normally used Computer programsare used in calculations of the various unit operations of the process plant Suchprograms are part of the large computer packages used in process simulations, but

In several cases, such as in handling of equipment or in relation among workers/operators/manufactured product and equipment involved, the factor “human being”has also to be considered Here, knowledge of work study can be very helpful.Empirical data and “rules of thumb” are used to facilitate the various design

The design of chemical process equipment is based on the principles of unitoperations and process engineering In analyzing the various industrial processes,

Equipment design yields quantitative data on required equipment, such asdimensions of pipes, power of pumps, surface area of heat exchangers, surface

area of evaporator heaters, dimensions of distillation or extraction columns, anddimensions of dryers In addition, the approximate quantities of the required plantutilities are calculated In equipment sizing, a safety or overdesign factor of15–20 % is normally used.

After the preliminary sizing of the process equipment, detailed specifications areset, which are necessary for purchasing the equipment from the suppliers At thisstage, a preliminary cost estimate of the equipment is made, using cost indices and

standard or “off-the-shelf” equipment should be used, which is generally lessexpensive and more reliable than nonstandard equipment Standard equipmentincludes pumps, heat exchangers, valves, standard evaporators, distillation col-umns, and centrifuges

When specialized or nonconventional equipment is needed, detailed tions are required which will help the fabricator to construct the appropriate unit(e.g., filters, chemical reactors, special dryers, and distillation columns) Some-times, special equipment is needed for a new process, for which there is noindustrial experience In such cases, a pilot plant installation may be required,which will supply the specifications for the desired industrial equipment Thescale-up ratio of capacities (industrial/pilot plant) is usually higher than 100:1.The utilities or auxiliary facilities, which are necessary for the operation of theprocessing plants, include energy, water, steam, electricity, compressed air, refrig-eration, and waste disposal Energy in the form of heat or electricity is needed forthe operation of the plant Heat is produced primarily by combustion of fuels (oil,gas, and coal) Water is supplied from the municipality or from the surroundingplant area (drilled wells, rivers, or lakes) and is required for process, sanitary, andsafety uses High-pressure steam may be used for power generation, and the exhauststeam is utilized for process heating Waste disposal involves the treatment of

The selection of the materials of construction of process equipment is veryimportant from the economic, operational, and maintenance points of view.Corrosion-resistant materials such as stainless steels may be required in handlingand processing corrosive fluids National and international construction codes arenecessary for plant and worker protection and for standardization of the process

are ASME (pressure vessels), TEMA (heat exchangers), ANSI (piping and mentation), and DIN (materials and construction)

The layout of process and utility equipment is essential to ensure the safety,operability, and economic viability of any process plant and for planning futureextensions A balance of many technical, operational, and economic factors must beachieved Plant layout follows the development of the PFD and the preliminary

sizing of the process equipment and is necessary before piping, structural, andelectrical design The layout of equipment should allow for a safe distance betweenthe units, facilitating the operation, servicing, and cleaning of each unit.

Plant layout is shown in engineering drawings or, if plants are more complex, in3D models, which are useful for construction engineers and for instruction of plantoperators

Plant buildings are needed mainly to house the process and utility equipment, thestorage areas, the plant offices and labs, and the personnel common rooms (cafe-terias, washrooms) In choosing the plant location, several factors should beconsidered, including raw materials, markets for the products, energy and watersupplies, waste disposal, labor supply, legal restrictions, and living conditions Insome large petroleum and petrochemical plants, several large units and the requiredpiping are installed outside the buildings (e.g., distillation columns, storage tanks)

In the installation of plant equipment, special attention should be paid to thefoundations of the heavy units, considering also any vibrations of rotating/recipro-cating equipment In the construction of industrial buildings, the local and federal(national) regulations and codes should be followed, particularly those that arerelated to the health and safety of the workers and the consumers and the protection

of the natural environment

Cost analysis is an important part of process and plant design Fixed capitalinvestment in process equipment, manufacturing costs, and general expensesshould be considered in the early stages of design

The fixed capital investment in process plants consists of a number of items,

the important cost items and their percentages of the fixed capital investment for a

cost of piping in chemical, petrochemical, and petroleum plants (mostly gas/liquidprocessing) is relatively high, compared to other processing industries, such aspharmaceuticals and foods (mostly solids processing)

The contingency item refers to unexpected approximate costs of the project Inaddition, a working capital of about 20 % of the fixed capital may be needed for theinitial operation of the plant

The installed utilities, representing about 15 % of the fixed capital, includeauxiliary buildings (5 %), steam (4 %), water supply (3 %), waste treatment

The fixed capital investment for a chemical plant can also be estimated by

Thus, the fixed capital (FC) can be broken down into four basic components, related

to the mechanical equipment (ME), electrical equipment (EE), plant buildings andsite or civil engineering works (CE), and overhead (OV), according to the following

The fixed capital can also be estimated from the process equipment cost (EC) bythe factorial method:

fluids processing, and 3.6 for mixed fluids/solids processing

In food processing, the installation, piping, and instrumentation and control costsare smaller than in chemical processing The base equipment is more expensive(stainless steel, hygienic requirements) than the chemical equipment As a result,

The working capital for a processing plant can be taken approximately as 20 %

of the fixed capital

The most accurate cost estimation for process equipment is to obtain a pricequotation from a reliable vendor (supplier of equipment) Specification sheets foreach process unit should be prepared for the equipment supplier The specificationsshould contain basic design data, materials of construction, and special information

Table 1.2 Fixed capital

investment for typical

that will help the supplier to provide the appropriate equipment Standardizedequipment should be preferred because of lower cost and faster delivery.

When approximate cost data are required for preliminary design, empiricalmethods and rules are used, which will yield fast results within the accepted

straight lines These charts are represented by the generalized cost–capacityequation:

ð1:3Þ

(e.g., kg/h), respectively

The capacity factor (n) varies with the type of equipment over the range 0.5–1.0

converted to year 2000, using the M&S index The capacity factor in this case is

and utilities of the main chemical processes Better cost estimates can be obtained

the main process, such as environmental installations and materials handling and

The cost of process equipment and processing plants changes over the years, due toinflation and other economic factors, and there is a constant need for updating the

1000

100 100

cost data For this reason, cost indices or empirical rules are used, like the M&Sindex (Marshall and Swift, formerly Marshall and Stevens), published periodically

The M&S equipment index is the weighted average of the cost of equipment foreight chemical process industries, including chemicals, petroleum, and paper Ittakes into consideration the cost of machinery and major equipment, plus costs ofinstallation, fixtures, tools, office furniture, and other minor equipment The basis of

The CE (chemical engineering) plant cost index, also published in the journalChemical Engineering, is the weighted average of chemical plant costs (66 items,including equipment, buildings, and engineering)

with a sharp rise during the decade 1970–1980, due to rising energy costs, and aleveling off after 1990 Cost indices are approximate mean values with variations

up to 10 % and recent annual inflation of about 4.5 %

Although most of the engineering indices refer to the US industry, they areapplied to chemical industries in other parts of the world, with little correction

CE index, can be developed, using approximate models, the constants of which can

the following main items: local steel price, labor cost, inflation index, and crude oilindex In case of limited operation of equipment due to early replacement, theireffective retail value should be also considered (see also p 38)

1.2.7 Manufacturing Cost and Profitability

Although the main objective of process economics is the profit on the investedcapital, some other criteria should also be considered in designing and building achemical process plant The plant should be operated and controlled safely for theworkers, the products should be safe and without adverse health effects to theconsumers, and the environment should not be damaged by plant wastes

The economic analysis of chemical processes and chemical plants is covered in

specialized economics books The elements of process economics, needed forpreliminary design, are summarized here

The manufacturing cost, usually calculated in USD/year, consists of two basicparts: (1) the direct or variable operating cost, which includes the cost of rawmaterials, labor, utilities, and overhead and the administrative costs, and (2) theindirect or fixed charges (USD/year), consisting of the depreciation of the fixedinvestment and the taxes/insurance Depreciation is usually taken as 8 % of thefixed investment, i.e., the fixed capital will be recovered in 12 years The productcost (USD/kg) is calculated by dividing the manufacturing cost by the annual

Process profitability can be estimated by the following simple economic

Table 1.3 Approximate cost

indices for process equipment

(M&S) and plants (CE)

Data from the Journal of Chemical Engineering

gross profit¼ gross sales  manufacturing cost ð1:4Þ

where FI is the fixed investment, ACF is the net annual cash flow, and AD is theannual depreciation

which the cumulative cash flow becomes equal to zero In the first years ofoperation, the ACF is negative, due to the high operating cost, but it turns into apositive net cash flow, after the payback time An alternative method of estimatingthe payback time is

The previous simplified economic analysis can be used in preliminary designand approximate cost estimations However, it does not consider the “value ofmoney,” i.e., the interest that could be earned from the fixed invested capital Indetailed design and in actual economic evaluations, the prevailing interest rate is

The annual discounted cash flow (ADCF) is related to the ACF:

value (NPV) and is calculated from the following summation:

The discounted cash flow rate of return (DCFRR) or return on investment (ROI)

is the fractional interest rate (i) for which NTV becomes equal to zero, after achosen number of years (n), and it is calculated as follows, using a graphical or atrial-and-error iteration technique:

The DCFRR is also known as the profitability index, initial rate of return (IRR),

In economic planning, the cost of replacement of major process equipment, after

a number of years, should be considered This is accomplished by reserving the

replacement cost (RC) of the equipment, which is converted to the capitalized cost(CC), using the prevailing annual interest rate (i), according to the following

The processing plant should be operated so that the total income is higher than thetotal product (operating) cost and a reasonable profit is realized At low rates ofproduction, the total income is lower than the total product cost, because the fixedcosts (e.g., depreciation, maintenance) remain constant and a financial loss isobtained The rate of production above which the operation is profitable is called

point is at a production capacity of about 50 % of the maximum plant capacity, andthe optimum operation is at about 80 % of maximum capacity For a combination ofreasons, the optimum operating capacity may not be the maximum productioncapacity

1.2.8 Computer-Aided Process/Plant Design

Although the design of chemical processes and chemical plants has been based untilrecently on practical experience and empirical rules, there has been a lot of activity

on the applications of computer-aided techniques in this important area of chemicalengineering Computer-aided process engineering (CAPE) has been the favoritesubject of university and industrial research and development projects, directedprimarily to large-scale chemical and petrochemical processes, both in the USA and

in other parts of the world Process design, which is the major component of CAPE,

is a major subject of the annual European Symposium on Computer-Aided ProcessEngineering (ESCAPE), the proceedings of which are published in the journalComputers and Chemical Engineering

Most of the progress in CAPE has been in the modeling, simulation, andoptimization of chemical processes, with emphasis on flow sheet development,separation processes, and energy utilization The processing of gases and liquidshas received particular attention, due largely to the availability of reliable predic-tion methods and databanks of the physical, thermodynamic, and transport proper-ties of the materials being processed Limited attention has been given to theprocessing of solids and semisolids, due to difficulties in modeling and to insuffi-cient data on engineering properties

In preliminary calculations for process design, general-purpose software is used,

HYSIM/HYSYS (Hyprotech Ltd.), and PRO II (Simulation Sciences), are used

universities and industries, can be applied to various process industries

Several computer programs have been adapted for use in PCs, utilizing fied software (e.g., Microsoft Windows) A list of such programs, convenient forpreliminary design and costing of chemical process equipment and plants, is

The computer-aided design (CAD) programs usually consist of an executivesystem; packages of physical, thermodynamic, and transport properties; and col-

software is available for preparing process flow sheets, piping and instrumentationdiagrams, and engineering drawings of chemical equipment and chemical plants.Two-dimensional (2D) drawings are normally used, but in special cases, three-dimensional (3D) drawings offer a better visualization of t instrumentation diahe

1.3 Design of Food Processes

The identification of food engineering and its objectives within food science is

in the design of food processes, replacing the empirical approaches of the past Inaddition to the principles and techniques of chemical process design, the design offood processes must be based on the principles and technology of food science andengineering

Successful and efficient manufacturing technologies, developed in other tries, can be adapted, modified, and implemented in the food industry Food qualityand food safety must receive special consideration, while applying the engineeringprinciples and techniques

indus-Food processing involves several physical unit operations and microbiological,biochemical, and chemical processes, which aim at preservation and improvement

of food quality or conversion to safe and nutritional food products in large,economic scale Food preservation and conversion technology has advanced con-

Food engineering has evolved into an interdisciplinary area of applied scienceand engineering, based primarily on chemical engineering and food science Thetraditional unit operations of chemical engineering have been adapted to foodprocessing, taking into consideration the complexity of food materials and their

The physical operations of food processing can be analyzed by applying theestablished concepts of unit operations and transport phenomena of chemical

engineer-ing considerations of process cost, energy optimization, and process control,demands on food quality and safety should be satisfied In this respect, application

of the principles and advances of food science is essential

The trend for improved product quality in all industries (product engineering)should be taken into consideration in all stages of process design In the foodindustry, advances in the developing field of food materials science should beconsidered, with respect to the effect of food handling, processing, and storage on

Process control and automation, adapted from other industries, must take intoconsideration the requirements of accurate control of safe thermal processing,time–temperature effects on product quality, and desired micro- and macrostructure

of food products

In the food industry, the trend for improved products (product engineering)should be taken into consideration in all stages of process design (Aguilera

or with the further processing of prefabricated products Besides food ing, an efficient design should also take into consideration aspects of supply,handling, and storage, and the successive kind of food trade (e.g import-export,

wholesale, cash and carry types of delivery markets and marketing) up to the finalconsumption of food.

high-added-value products; (2) constant output of manufactured products, as far as possible;and (3) permanently constant high quality of produced food

(2) constant good quality of the retail products, (3) compliance with the fications and standards, (4) possibility to extend the shelf life of the products, and(5) facility in handling, including transportation

(2) satisfaction of an easy-to-use trend, (3) good quality, and (4) reasonableprice

contamination], (2) dietary suitability [e.g., adequate nutrition], (3) processsuitability [e.g., the right initial raw food material for manufacturing certainfoods], and (4) sensory characteristics, such as odor and optical properties,texture, acoustic properties (e.g., crispy products), and taste

Basic elements for improvement of food quality are marketing and research

marketing–food development–food processing–consumption

It is important to foresee the right time that a product has to be renewed or replaced

tangents on the breaking points of the curves are drawn: Total sales of a product as

should surpass the already achieved sales of the removed product The term “newproducts” does not always refer to essentially new products As “new” are alsocharacterized products that are based on line extensions or formulations This

The introduction of “new” products is essential for the welfare of food factories.However, probably not all products indicated as “new food products” may be reallynew! There is some disagreement on what a food product may be called “new.”Often there is diversification concerning what the industry or the consumers face asnew Often for the industry, the “new” simply reflects only a new appearance such

extension of already existing products, while the consumers do not agree that newitems are not the same as new products

It is estimated that the number of “new products” of food introduced every year

informa-tion of the Marketing Intelligence Service Ltd., of about 11,000 new foods duced in USA in 1996, only 7.2 % featured real innovations A.C Nielsen andLitton Matysiak and Wilkes, Inc., reported that only 8.9 % of “new products” in

intro-1995 were actually new Furthermore, according to a study concerning the 20 mostnew products introduced by US companies, in which certain restrictions were put

for the use of the term “new,” only 9 % of the called “new” products were indeed

A successful investment in research contributes to the long life cycle of a newproduct in the market However, only a small number of genuinely new developedproducts are tested in an actual market, and furthermore, only a smaller part out ofthem finally survives in the market Large companies often prefer to cooperate orincorporate the smaller ones when the new invented products promise good market

flexible in presenting “new products.”

Proposals

Reconnaissance

and prediction

Control of requirements for disposal

Marketing

Analysis and design of new product

Ensuring of

"deliveries"

Processing

Processing and Production

Design and securing supplies

Control of processing requirements

Disposal

Fig 1.4 Relation of food processing–marketing

Food plant control should cover the whole spectrum from delivery of rawmaterials up to consumption Two main categories of control in food manufacturingmay be distinguished: (1) control related to the means of processing/manufacturingand (2) control of products.

1 In processing, control and automation adapted from other industries must takeinto consideration the requirements of accurate control of safe thermalprocessing, time–temperature effects on product quality, and the desired

length of research work for the product A

Fig 1.6 Influence of research on the life cycle of a product

micro- and macrostructure of food products Control is extended to(a) equipment (condition, maintenance, etc.), (b) operational parameters (con-ditions of processing), (c) main installations (hydraulic and electric installation,buildings), and (d) auxiliary installations (energy, water supply, wastes, etc.).

2 Product control includes (a) incoming deliveries (raw materials, additives,packaging materials, etc.) and (b) control of products during and after processing(storage, handling, transport, retail) In some cases, it may be extended tocontrols that are related to environmental factors (quality of water, air, etc.).Main categories of product control are (a) microbiological and biological ana-lyses (decay, infections, etc.), (b) chemical analyses (composition, residualsubstances, chemical reactions), and (c) technical analyses (packaging material,texture, sensory evaluation, etc.) Details on food quality and safety programs

The basic unit operations of chemical engineering, i.e., fluid flow, heat transfer, andmass transfer, have been applied to the food processing industry for many years.The theory on these operations was developed originally for gases and liquids(Newtonian fluids), which constitute the main materials of the chemical industry

mostly with non-Newtonian fluids and semisolid and solid food materials, andadaptation or extension of the theory is necessary Some food processing opera-tions, dealing with such complex materials, are still treated empirically, using rules,

comprehensive review of food process engineering operations is presented by

Due to the diversity of food processes and food products, several specialized unitoperations were developed in the food processing industry (Ibarz and Barbosa-

the purpose of food processing, i.e., separation (mechanical, physical, thermal,chemical), assembly (mechanical, physicochemical), and preservation (heat, cold,drying, chemical, irradiation) In addition, packaging operations must beconsidered

and mechanical properties of the materials) and physical separations (based onmass transfer rates of components at interphases) The latter are often listed as mass

solid/solid separations, developed through experience, are used in food processingoperations Thus, in the processing of fruits and vegetables, the following mechan-ical operations are applied: abrading, crushing, cutting, dividing, expressing (juice),

filtering, finishing, grinding, peeling, pitting, shelling, sieving, sizing, slicing, andstemming.

opera-tions Examples of assembly operations include agglomeration, coating, forming,enrobing, mixing, extrusion, molding, pelleting, stuffing, emulsification, crystalli-zation (from melt), baking, and foaming

the spoilage cause (microbes, enzymes, pests, and chemicals) Preservation tions can be subdivided into three major categories: physical, chemical, andmechanical The physical operations include heating (frying, boiling, pasteuriza-tion, sterilization, blanching, cooking), cooling (chilling, freezing), and drying(dehydration, desiccation, evaporation) Chemical preservation includes permittedchemical substances, such as vinegar and lactic acid The mechanical operationsinclude cleaning, washing, sorting, and high pressure However, in some cases offood, mechanical operation is not clear Extrusion, e.g., is a mechanical as well asthermal (physical) process

opera-For the purposes of this book, the unit operations of food processing areclassified on the basis of the processing equipment, with typical examples shown

biochem-ical, or microbiological) In this sense, some of the processing operations, listed in

microbiolog-ical reaction), blanching (biochemmicrobiolog-ical and physicochemmicrobiolog-ical reactions), and ation (energy absorption and microbiological reaction)

irradi-Food quality considerations are very important in the selection and operation ofprocesses Food materials can be considered as either living or nonliving plant(or animal) tissues In food processing, fresh fruits and vegetables are considered toconsist of living tissues Dried plant foods and animal tissues are generally consid-ered as nonliving tissues The quality of living tissues is influenced by storageconditions of temperature, relative humidity, and gas atmosphere In most foodprocessing operations, the food materials consist mostly of nonliving tissues

In fruit and vegetable processing, heat treatment operations, such as blanching,cooking, and sterilization, convert the living into nonliving tissues Optimization ofheat treatment operations is possible, since the rate of destruction of spoilagemicroorganisms and enzymes is faster than the rate of quality deterioration (unde-sirable changes in color, flavor, structure, and nutritive value)

A practical description of the unit operations, used in the processing of fruits and

large industry worldwide, consisting of a large number of small- to medium-sizedprocessing plants and producing several diverse food products These plants utilizeseveral and often specialized unit operations, since the materials being processedare solids or semisolids, sensitive to mechanical and thermal processing On theother hand, the dairy, edible oil, milling, and beer industries deal with largeamounts of fewer products, utilizing a smaller number of standard unit operations

Table 1.4 Classification of unit operations of food processing

Mechanical processing (Chaps 4 and 5) Peeling, cutting, slicing

Size reduction Sorting, grading Mixing, emulsification

Extrusion, forming

Cleaning, washing Filtration Mechanical expression Centrifugation

Pneumatic conveying Hydraulic conveying Mechanical conveying Heat transfer operations (Chaps 6, 9, and 10) Heating, blanching

Cooking, frying Pasteurization Sterilization Evaporation Cooling, freezing, thawing Mass transfer operations (Chaps 8 and 11) Drying

Extraction, distillation Absorption, adsorption Crystallization from solution Ion exchange

Reverse osmosis

Lactic fermentations Dairy fermentations

High pressure Pulsed electric fields

Metallic, plastic packages Aseptic packaging Modified atmosphere, vacuum

The scale-up methods, used successfully in chemical engineering, are difficult toapply, even to continuous food processing operations, due to the complex physical,chemical, and biological reactions in the food systems Pilot plant data, undersimilar processing conditions, are necessary for scale-up to industrial operations

of complex food processes, like extrusion cooking of starch-based foods (Valentas

The pilot plant is useful in determining new food processes and in testing newprocessing equipment under industrial-like operating conditions It is often used forthe production of large samples of new food products, which are needed for storageand marketing tests

The required unit operations of a food processing plant should be arranged in theproper sequence, i.e., a plant layout should be followed

A number of empirical specifications and standard practices (good ing practices, GMPs) are necessary for the hygienic and safe operation of food

In food process design, flow sheets similar to those of chemical process design areused, i.e., process block diagrams (PBDs), process flow diagrams (PFDs), processcontrol diagrams (PCDs), and process instrumentation and piping diagrams (PIDs)

material and energy balances in graphical form Materials handling diagrams arealso useful, since they describe interconnections of processing operations, even ifthey are located in different buildings or even sites

The selection of an optimized process flow sheet in the chemical and chemical industries requires extensive computer calculations, due to the largenumber of possible process configurations However, the realistic process config-urations in a given food processing system are limited, because there is usually onlyone major operation or process in a given flow sheet, which defines more or less theother auxiliary operations

petro-CAD uses mainly 2D flow sheets for various process, equipment, and plantrepresentations In special cases, 3D diagrams are useful for a better visualization of

edible oil processing, where materials transport and piping play a dominant role.PBDs are normally used for a quick representation of the process and forpreliminary calculations of material and energy balances Each rectangular blockrepresents individual unit operations or group of operations The PFDs or processflow sheets show more details of the process or plant, using specific symbols forequipment, piping, and utilities They are simple and any changes may be doneeasily Both PBD and PFD flow sheets can show process details, like material flow

rates (kg/h), energy flows (kW), temperatures (C), and pressures (bars) They can

be combined with tables of data

PCD show the position of the control units in the processing lines and theirconnection to the sensors PIDs indicate the type and location of instrumentationand the type and connections of pipes There are no generally accepted standards forprocess symbols in flow sheets There are some universally applied symbols forchemical process equipment, listed in the chemical engineering literature, e.g.,

In addition to the PBD and PFD, diagrams showing the exact position of theprocessing equipment in the food plant (ground plans) are also used Front and sideviews of the processing line may also be required

For illustrative purposes, one block diagram and one process flow sheet for the

of processing equipment, which will be analyzed in detail in the examples ofsubsequent chapters of this book

visualization of the plant and equipment The same tomato paste plant is shown in

separation of oil from orange peels may include an oil press, a grinder, a mixer of

The principles and techniques of material and energy balances of chemical neering are, in general, applicable to most food process calculations However, foodprocesses require special attention, due to the complexity of food materials and theimportance of food quality In material balances, accurate food composition dataare difficult to obtain, due to variability even for the same food material Variationsare due to the variety, growing conditions, and age of the raw materials If reliableexperimental data are not available for the food material being processed, approx-imate values can be obtained from the literature, e.g., the USDA food composition

Simple material and energy balances can be performed on mechanical and heatpreservation operations Simultaneous heat and mass transfer operations, such asdrying, blanching, baking, and steam injection, may need more detailed analysisand experimental verification of the assumptions on food composition and energy

material and energy balances may be required periodically, during the operation ofthe food processing plants

Overall and component material balances are calculated at the boundaries of afood process, from the mass conservation equations in the system:

ð1:15ÞFor continuous operations, the accumulated materials (total and component) areequal to zero

ESSENCE

Essence

HTST STERILIZATION

ASEPTIC PACKAGING

PACKAGED OJ

ANIMAL FEED 10% Moisture

PEEL OIL 0.3

8.3

2.3 5.16

0.2

9 2.3

2.3 5.16

6.46

COJ COJ

12° Brix 12° Brix

65°Brix

COJ 65° Brix

9 1

10

10 35

45 45 48 95

95

5

100 100

Oranges

47 Pulp Pomace

3

35

OJ

OJ OJ

9 CANNED FCOJ

BULK PACKED FCOJ

DEBITTERING

DRYING Pomace Pomace

49.7 15.2 %TS

CO

w

c cw

Peels

4 5

BULK FCOJ

85 Brix

17 16

15 RF

18 RF

COJ 42 B COJ 86 B

Fig 1.9 Simplified 3D PFD for a tomato paste processing plant (see Fig 1.10)

15 9 8

8 6 5 4 3 2

7

3'

Fig 1.11 Floor plan (layout of equipment) of a tomato paste plant (see Fig 1.10)

The component material balance (Eq.1.15) can be written for one or more foodcomponents, which are important in a given processing operation Typical compo-nents, involved in food processing, are water (moisture), total solids (TS), solublesolids (SS), fat, oil, salt, and protein The soluble solids are usually expressed as

in the laboratory and the processing plant The concentration of components is

Energy balances are calculated at the boundaries of a food process, from theenergy conservation equation (first law of thermodynamics) in the system:

For preliminary design calculations and equipment sizing, the main energy formconsidered is heat and only heat balances are calculated The mechanical andelectrical requirements for pumping, transportation, refrigeration, and operation

of the various pieces of process and utility equipment are considered in the detailedprocess, equipment, and plant design

Heat balances involve the enthalpy and specific heats of the various process and

while all food materials have lower values The heat of evaporation or condensation

Thermophysical and thermodynamic data for foods are obtained from food

properties in food process and equipment design was discussed by Saravacos

The material and energy balances are essential in the design of food processes,processing equipment, process utilities, and waste treatment facilities, in processoptimization and control, and in cost analysis of the process and the processingplant The sizing, design, and selection of food processing equipment are discussed