Process Equipment and Plant Design: Principles and Practices

Description

Process Equipment and Plant Design: Principles and Practices takes a holistic approach towards process design in the chemical engineering industry, dealing with the design of individual process equipment and its configuration as a complete functional system. Chapters cover typical heat and mass transfer systems and equipment included in a chemical engineering curriculum, such as heat exchangers, heat exchanger networks, evaporators, distillation, absorption, adsorption, reactors and more. The authors expand on additional topics such as industrial cooling systems, extraction, and topics on process utilities, piping and hydraulics, including instrumentation and safety basics that supplement the equipment design procedure and help to arrive at a complete plant design. The chapters are arranged in sections pertaining to heat and mass transfer processes, reacting systems, plant hydraulics and process vessels, plant auxiliaries, and engineered safety as well as a separate chapter showcasing examples of process design in complete plants. This comprehensive reference bridges the gap between industry and academia, while exploring best practices in design, including relevant theories in process design making this a valuable primer for fresh graduates and professionals working on design projects in the industry. Process Equipment and Plant Design: Principles and Practices Copyright Dedication About the Authors Preface Acknowledgement Introduction 1 . General aspects of process design 1.1 Process 1.2 Design problem and its documentation 1.3 The design process Qualitative considerations can be Quantitative considerations Optimum design Design steps 1.3.1 Deliverables 1.4 Organisation of the Book Further reading Introduction 2 . Heat transfer processes in industrial scale 2.1 Introduction 2.2 Exchanger types 2.2.1 Recuperator 2.2.2 Regenerator 2.2.3 Fluidised bed exchanger 2.2.4 Direct contact heat exchanger 2.3 Flow arrangement 2.3.1 Countercurrent flow exchanger 2.3.2 Co-current flow/parallel flow exchanger 2.3.3 Cross-flow exchanger 2.3.4 Split flow exchanger 2.3.5 Divided flow exchanger 2.3.6 Multipass exchanger 2.4 Exchanger selection 2.5 Heat exchanger design methodology Process and design specifications 2.6 Design overview for recuperators 2.6.1 Thermal design The effectiveness-NTU method 2.7 Estimation of overall design heat transfer coefficient Further reading 3 . Double pipe heat exchanger 3.1 Introduction 3.2 Design 3.2.1 Input data 3.2.2 Deliverables 3.2.3 Codes and standards 3.2.4 Guidelines to select inner and outer fluid 3.2.5 Design considerations 3.2.6 Thermal design 3.2.7 Hydraulic design 3.3 Series-parallel configuration of hairpins 3.4 Design illustration 3.4.1 Design steps 3.4.2 Design example References Further reading 4 . Shell and tube heat exchanger 4.1 Introduction 4.1.1 General description Shell Exchanger Head(s) Tubes Tube sheet Baffle Tie rods and spacers Impingement baffle Multipass exchanger Shell passes 4.1.2 Heat exchanger installations and commissioning 4.2 Codes and standards 4.3 Design considerations Process Mechanical 4.3.1 Input data for design 4.3.2 Design output Process design Mechanical details Fabrication details 4.4 Design – FT method 4.5 Pressure drop estimation 4.6 Mechanical detailing 4.6.1 Exchanger material 4.6.2 Tube length 4.6.3 Tube sheet details 4.6.4 Tube pass pattern 4.6.5 Finned tubes 4.6.6 Segmental baffles (transverse baffles in BIS code) 4.6.7 Tie rods 4.6.8 Impingement baffle 4.6.9 Shell dimensions 4.6.10 Channel and channel cover 4.6.11 Nozzles 4.6.12 Exchanger support 4.7 Design illustration Further reading 5 . Heat exchanger network analysis 5.1 Introduction 5.2 Energy-capital trade-off – two-stream problem 5.3 Multi-stream problem 5.3.1 Optimal ΔTmin 5.3.2 Practical values of ΔTmin 5.4 Pinch design analysis 5.4.1 Locating the pinch using the problem table algorithm 5.4.2 The pinch principle 5.4.3 Design strategy 5.4.4 Grid diagram Tick off heuristic 5.4.5 Stream splitting in network design 5.4.6 Network simplification: heat load loops and heat load paths 5.5 Targeting for multiple utilities 5.6 Design algorithm 5.7 Threshold problems 5.8 Data extraction 5.8.1 Composite curve for non-linear CP 5.8.2 Avoid mixing of streams at different temperatures 5.8.3 Use effective temperatures 5.8.4 True utility streams 5.9 Applications 5.10 Design illustration Composite curves Problem table algorithm Further reading 6 . Evaporators 6.1 Introduction 6.2 Components of an evaporation system 6.3 Evaporator types 6.3.1 Types of continuous evaporators Evaporators without heating surfaces 6.4 Evaporator performance 6.4.1 Multiple-effect evaporators Feeding arrangements Use of vapor as a “hot stream” in the plant 6.4.2 Vapor recompression 6.4.3 Heat recovery systems 6.4.4 Evaporator selection 6.5 Evaporator accessories 6.5.1 Condensers 6.5.2 Vent systems Salt removal 6.6 Evaporator design 6.6.1 Single-effect evaporation 6.6.2 Multiple effect evaporation Optimum number of effects in a multiple-effect system 6.6.3 Design data Elevation of boiling point (BPE) Boiling point elevation in multiple effect evaporators Enthalpy plots Tsteam & Tcon Steam pressure Pressure in the vapor space Influence of feed, steam and condensate temperature 6.6.4 Design algorithm for multiple-effect evaporator Design input Design objective Design deliverables Design algorithm 6.7 Design illustration Design example 1 Process design deliverables Design example 2 Deliverables Further reading 7 . Industrial cooling systems 7.1 Introduction 7.2 Cooling tower 7.2.1 Classification Classification by build Classification based on air draft Classification based on airflow pattern Classification based on the heat transfer method 7.2.2 Components of a typical cooling tower 7.2.3 Cooling tower parameters 7.2.4 Cooling water circuit in a process plant 7.2.5 Codes and standards 7.2.6 Thermal design 7.2.7 Notes on design and operation 7.3 Design illustration Summary of available data Tower selection Fill details Determination of operating L/G for the fill chosen Steps of calculation Fan power calculation Estimating head loss in the fill and water distributor level Estimating make up water (M) requirement Evaporation loss (E) Drift loss (D) Pump calculations Cooling tower sump Further reading Introduction 8 . Interphase mass transfer 8.1 Introduction 8.2 Processes and equipment 8.3 Process design and detailed design of the equipment 9 . Phase equilibria 9.1 Introduction 9.2 Representation of concentration 9.3 Representation of equilibrium 9.3.1 Graphical representation of equilibrium 9.3.2 Mathematical representation of equilibrium VLE: Distillation Solubility: absorption and stripping GSE and LSE: adsorption LLE: extraction Further reading 10 . Absorption and stripping 10.1 Introduction 10.2 Tray column 10.2.1 Graphical determination of the number of contacting stages Minimum required liquid flow rate (Lmin) in case of absorber for a given gas rate (G,G′) Approximations for low concentration system 10.2.2 Absorption factor 10.3 Packed column 10.3.1 Packed column design based on mass transfer coefficient 10.3.2 Driving force line 10.3.3 Overall mass transfer coefficient 10.3.4 Estimation of active bed height 10.3.5 Design based on liquid-phase resistance 10.3.6 Absorption accompanied by chemical reaction 10.4 Design illustration Driving force lines Estimating mass transfer coefficients Further reading 11 . Distillation 11.1 Introduction 11.2 Conceptual design 11.3 Detailed design 11.4 Fractionator 11.4.1 Process design of fractionating tower – equilibrium stage approach 11.4.2 Binary fractionation 11.4.3 Multicomponent distillation 11.5 Design illustration – fractionator 11.6 Flash distillation 11.6.1 Design equations 11.6.2 Design considerations 11.6.3 Design steps 11.7 Design illustration – flash distillation 11.8 Batch distillation 11.8.1 Design 11.8.2 Design deliverables 11.8.3 Design steps 11.9 Design illustration – batch distillation Further reading 12 . Adsorption 12.1 Introduction 12.1.1 Modes of operation Stagewise operation Continuous contact operation 12.1.2 Adsorption mechanisms 12.1.3 Adsorption equilibrium 12.2 Packed bed adsorption 12.2.1 Breakthrough curve, breakthrough point, and bed exhaustion 12.2.2 Desorption/regeneration Gas-phase adsorption Liquid-phase adsorption 12.2.3 Adsorbent aging 12.2.4 Bed design Rigorous methods Empirical or short-cut methods Pilot plant design Data/information required for design Operating parameters from pilot tests (a) Loading rate/filtration rate (LR) for liquid-phase applications (b) Superficial velocity (Us) for gas-phase applications (c) Empty bed contact time (d) Breakthrough time (tb) (e) Fraction of bed utilised (f) (f) Adsorbate loading (qs) Bed design Volume of fluid treated/change out period Pressure drop Bed configuration and mode of operation 12.3 Design illustration Further reading 13 . Extraction 13.1 Introduction 13.2 Extractor types and selection 13.2.1 Extractor types Stagewise contact Continuous contact 13.2.2 Contactor selection 13.3 Choice of solvent 13.4 Design of continuous countercurrent contactors Flooding 13.4.1 Calculation of the number of stages 13.4.2 Design parameters for extraction towers 13.5 Design of mixer-settler 13.5.1 Holding time 13.5.2 Power and mixing time 13.5.3 Scale-up 13.5.4 Flow mixers 13.6 Design illustrations Further reading 14 . Column and column internals for gas–liquid and vapour–liquid contacting 14.1 Introduction 14.2 Tray towers 14.2.1 Contacting trays Downcomer Outlet weir Liquid bypass baffles Bottom tray seal pan Weep holes Vapour disperser elements 14.2.2 Choice of tray type 14.2.3 Tray construction 14.2.4 Efficient operation of contacting tray 14.3 Tray design 14.3.1 Bubble cap tray design Tower diameter Check for entrainment Tray passes Outlet weir Height over weir Downcomer area Cap size Number of caps Area fractions over tray Liquid gradient across tray Tray pressure drop (htray, mm of liquid) Check for vapour distribution Vapour velocity and corrected ‘approach to flooding’ Downcomer pressure drop (hdc,prdrop, mm of liquid) Downcomer backup (hL,dc, mm of liquid, for all cross-flow trays) Velocity and residence time in downcomer Downcomer throw over the weir System (foaming) factors (applicable for all cross-flow trays) Weep holes 14.3.2 Sieve tray design (cross-flow type – with downcomer) Steps of design 14.3.3 Valve tray design 14.4 Packed tower 14.4.1 Choice of packing Packing types and size 14.4.2 Liquid distribution Liquid distributor Redistributor and collector 14.4.3 Bed support 14.4.4 Flooding and pressure drop in randomly packed bed Bed diameter estimation based on flooding and pressure drop Pressure gradient Minimum wetting rate 14.5 Packed tower design 14.6 Chimney tray, reflux entry, feed tray and tower bottom 14.6.1 Chimney tray 14.6.2 Reflux entry arrangement on top tray 14.6.3 Feed tray 14.6.4 Tower bottom arrangement 14.7 Design illustration Further reading Introduction 15 . Reactors and reactor design 15.1 Introduction 15.2 Design of reacting system 15.2.1 Reactor types 15.2.2 Rate and extent of reaction Rate-limiting step 15.3 Reactor design 15.3.1 Reaction/process conditions 15.3.2 Design deliverables Performance equation for idealized reactors 15.3.3 Scale-up 15.3.4 Bioreactors Sterilization 15.4 Design illustration Further reading Introduction 16 . Plant hydraulics 16.1 Introduction 16.2 Pumps 16.2.1 Common pump types Centrifugal Pump Positive displacement pumps Reciprocating pumps Rotary pumps Diaphragm pump 16.2.2 Pump performance and hydraulics 16.2.3 Cavitation NPSH in centrifugal pump Liquid vapour pressure NPSH in reciprocating pumps 16.2.4 Characteristic curve for centrifugal pumps Q-H curve Pumps in series and parallel Q-SHP (or BHP) Curve Q-NPSHRCurve 16.2.5 System characteristic curve 16.2.6 Adjusting centrifugal pump performance 16.2.7 Characteristic curves for positive displacement pumps 16.2.8 Pump selection 16.2.9 Steps of design for a hydraulic circuit 16.3 Compressors 16.3.1 Compressor selection 16.3.2 Centrifugal compressor Characteristic curve 16.3.3 Compressor hydraulics Capacity and pressure ratio Power Head developed 16.3.4 Design/sizing 16.3.5 Capacity control 16.4 Piping 16.4.1 Piping codes 16.4.2 Pipe size 16.4.3 Piping services 16.4.4 Pipe rack 16.4.5 Pipe joints 16.4.6 Pipe fittings Pressure relief–safety devices Other fittings 16.4.7 Pressure drop in pipeline 16.4.8 Few typical process piping systems Purge out operation Vent and drain system Flushing connections Control valve installation Steam trap Good practices for piping layout 16.5 Hydraulic calculations Further reading 17 . Process vessels 17.1 Unfired pressure vessels 17.2 Vessel components and fixtures 17.3 Mechanical design 17.3.1 Design Parameters 17.3.2 Vessel sizing Vapour-liquid separator Separator with wire mesh mist eliminator (demister pad) Reflux drum Liquid-liquid separator 17.3.3 Nozzle dimensions and location 17.3.4 Manhole specifications 17.3.5 Wall thickness 17.4 Design illustrations Further reading Introduction 18 . Utility services in process plants 18.1 Introduction 18.2 Fuel systems 18.2.1 Fuel gas 18.2.2 Fuel oil 18.2.3 Design of fuel system 18.3 Electrical power 18.4 Steam 18.5 Compressed air 18.5.1 Air supply scheme 18.5.2 Design illustration – compressed air system 18.6 Inert gases 18.7 Water 18.8 Efficient use of utilities Further reading 19 . Plant instrumentation and control 19.1 Introduction 19.2 Control loop 19.2.1 Feeback and feedforward Selection–feedback versus feedforward 19.2.2 Characteristic features of a process being controlled 19.3 Analog signals–pneumatic and electronic 19.4 Control algorithms 19.4.1 P, PI and PID controllers Choice of P, PI, or PID controller 19.4.2 Few advanced configurations of controllers Cascade control Split range control 19.5 Measurement of process parameters 19.5.1 Temperature measurement Thermocouple versus RTD 19.5.2 Pressure measurement Measurement of differential pressure 19.5.3 Flow measurement 19.5.4 Level measurement 19.6 Control valves 19.6.1 Fail-open and fail-close valves 19.6.2 Valve size 19.7 Instrumentation for safety 19.8 Distributed control system (DCS) 19.9 Control schemes for common processes 19.9.1 Distillation control and instrumentation 19.9.2 CSTR instrumentation and control Further reading 20 . Engineered safety 20.1 Introduction 20.2 Hazardous area classification 20.3 Trips and alarms 20.4 Blowdown and flare 20.4.1 Blowdown 20.4.2 Safety and pressure relief valves 20.4.3 Flare system 20.5 HAZOP Problem statement Report Major recommendations Worksheets Worksheet WS–1 Worksheet WS–2 Further reading Introduction 21 . Process packages 21.1 Process package deliverables 21.2 Examples 21.2.1 Design illustration 1 Design of 10,000 MT/Annum plant to manufacture Ethyl acetate from Ethanol 21.2.2 Design illustration 2 Design of a facility for a refinery to treat 8000m3/d of wastewater Further reading Graphical symbols for piping systems and plant Based on BS 1553: PART 1: 1977 Scope Appendix B: Corrosion chart Physical property data bank Conversion factors Typical fouling factors in m2K/W compiled from various sources Heat exchanger tube sizes and other details List of different standards commonly used Index A B C D E F G H I J K L M N O P Q R S T U V W