Applied Chemical Process Design

Transcription

1 Applied Chemical Process Design

2 Applied Chemical Process Design FRANK AERSTIN AND GARY STREET Dow Chemical Midland, Michigan With a Foreword by K. D. Timmerhaus PLENUM PRESS NEW YORK AND LONDON

3 Library of Congress Cataloging in Publication Data Aerstin, Frank. Applied chemical process design. Includes index. 1. Chemical processes. 2. Chemical engineering. I. Street, Gary, joint author. II. Title. TP A35 ISBN-13: DOI: / ' e-isbn -13 : First Printing-November 1978 Second Printing - May 1980 Third 'Printing - January 1982 Fourth Printing-October Plenum Press, New York Softcover reprint of the hardcover 1st edition 1978 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y All rights reserved No part of this book may be reproduced, stored in a retrieyai system, or transmitted, in any form or by any means electronic, mechanical, photocopying, microfjiming, recording, or otherwise, without written permission from the Publisher

4 Contents Foreword.... Preface.... List of Figures.... List of s.... Conversion s Agitation and Mixing Agitators Motionless Mixers Cooling Towers... ~ Decanters Distillation Basic Laws Shortcut Method-Optimum Trays and Optimum Reflux Ratio Flash Vaporization Selection of Internals Tray Column Diameter Tray Overall Efficiency Packed Column Design Packed Column Diameter and Pressure Drop Economic Evaluation Fluid Flow Fluid Flow-Single Phase Fluid Flow-Two Phase Flow through Orifices 7. Gas-Solid Separations..., Heat Transfer Heat Transfer Coefficients Heat Losses from Tanks... : Heating of Process Piping and Vessels-Heat Losses from Insulated Pipelines Heating of Process Piping and Vessels-Steam Tracing vii ix xi xv V

5 vi CONTENTS B.5. Heating of Process Piping and Vessels-Dowtherm SR-1 Tracing. 124 B.6. Double Pipe Exchangers 128 B.7. Shell and Tube Heat Exchangers B.B. Heat Transfer Coefficient in Agitated Vessels B.9. Falling Film Coefficients B.10. Reboilers and Vaporizers B.11. Condensers. 154 B.12. Air-Cooled Heat Exchangers B.13. Unsteady-State Heat Transfer Hydroclones Materials Physical Properties Dimensions and Properties of Piping Pump Sizing Safety Relief Valves and Rupture Disks Steam Ejectors for Vacuum Service Tank Capacity Dimensions and Properties of Steel Tubing Vapor-Liquid Separators Vessel Design Index

6 Foreword Development of a new chemical plant or process from concept evaluation to profitable reality is often an enormously complex problem. Generally, a plant-design project moves to completion through a series of stages which may include inception, preliminary evaluation of economics and market, data development for a final design, final economic evaluation, detailed engineering design, procurement, erection, startup, and production. The general term plant design includes all of the engineering aspects involved in the development of either a new, modified, or expanded industrial plant. In this context, individuals involved in such work will be making economic evaluations of new processes, designing individual pieces of equipment for the proposed new ventures, or developing a plant layout for coordination of the overall operation. Because of the many design duties encountered, the engineer involved is many times referred to as a design engineer. If the latter specializes in the economic aspects of the design, the individual may be referred to as a cost engineer. On the other hand, if he or she emphasizes the actual design of the equipment and facilities necessary for carrying out the process, the individual may be referred to as a process design engineer. The material presented in this book is intended to aid the latter in developing rapid chemical designs without becoming unduly involved in the often complicated theoretical underpinnings of these useful notes, charts, tables, and equations. The authors have attempted to emphasize those areas most often encountered in chemical process design, namely heat transfer, mass transfer, fluid flow, and mixing. Other design areas considered, but to a lesser extent, include cooling towers, liquid-liquid separations, gas-solid separations, vapor-liquid separations, pumps, safety valves and rupture disks, steam ejectors, and vessel design. These design procedures are supplemented with information on the thermal and transport properties of many materials and chemicals needed in the design of such process equipment, the mechanical properties of a host of metals commonly used in their construction, and the dimensions and properties of steel piping and tubing. In addition, two measures of economic profitability have been included to assist the process design engineer in justifying a specific design or process to management. vii

7 Preface Applied Chemical Process Design was prepared to give the chemical process engineer a ready reference that can be used at the office, in the field, or while on business travel. After spending several years in the chemical industry, we had found that each of us had a rather scattered collection of useful notes, charts, tables, articles, etc. The need to organize and consolidate these references was obvious. This book has been intentionally kept concise, to maintain its usefulness while in the field. Theory has been virtually eliminated. However, the material presented is adequate to solve many design and/or plant problems. Those wishing to learn more of the background or theory behind the methods presented should consult the references and selected readings given at the end of each chapter. The areas given the highest priority are those encountered most often: agitation, distillation, heat transfer, and fluid flow. The book is intended to help students, process design engineers, pilot plant engineers, and production engineers. It is hoped that it will be of particular value to younger engineers in bridging the gap between theory and application. Acknowledgments We would like to express our thanks to our colleagues at Dow Chemical, USA, whose constructive comments have been very helpful. In particular, the help of Lanny Robbins, Bruce Lovelace, Clarence Voelker, James Huff, Gerald Geyer, Douglas Leng, Thomas Tefft, Leo Schick, Jay Bleiweiss, James May, Paul Handt, and Kenneth Coulter has been appreciated. We would also like to thank Dr. James Pfafflin (Stevens Institute of Technology) and Dr. Harold Donnelly (Wayne State University) for their comments and help. Finally, we would like to thank the department secretaries (Susan Krantz, Erna Nash, Barbara Talicska, Anne Marie Duranczyk, and Nancy Roop), whose patience and perseverance have been greatly appreciated. Frank Aerstin Gary Street IX

8 Figures Figure 1.1. Tank and agitator dimensions Figure 1.2. Turbine power correlations Figure 1.3. Power correlations for glassed steel agitators Figure 1.4. "A" factor vs. Reynolds number in the laminar flow region Figure 1.5. "E" factor vs. Reynolds number in the turbulent flow region Figure 1.6. Darcy's friction chart Figure 1.7. LPD laminar flow Figure 1.8. ISG laminar flow Figure 1.9. LPD turbulent flow Figure ISG turbulent flow Figure Parameters for pressure drop in liquid-gas flow Figure 2.1. Cooling tower performance curves Figure 2.2. Induced draft cooling tower sizing curve Figure 2.3. Typical parts and framing for a crossflow cooling tower Figure 3.1. Decanter piping Figure 3.2. Sizing discharge piping from gravity decanters Figure 3.3. Liquid-liquid gravity decanter with circular overflow weirs and adjustable interface position Figure 4.1. Fenske equation for minimum plates Figure 4.2. Relation between optimum-to-minimum ratio and Fenske separation factor of aavg values Figure 4.3. Optimum-minimum reflux ratio relationship to the column's feed, distillate, and bottoms composition.. 42 Figure 4.4. Underwood's (J vs. key ratios in feed Figure 4.5. Underwood's (J vs. (a - (J)/a for a in range of Figure 4.6. Underwood's (J vs. (a - (J)/a for a in range of Figure 4.7. Underwood's (J vs. (a - (J)/a for heavy key and heavier components xi

9 XII FIGURES Figure 4.8. Effect of thermal condition of feed on feed tray location Figure 4.9. Capacity parameter for column diameter Figure Tray overall efficiency Figure Generalized pressure drop correlation in packed towers Figure 6.1. Correction for pressure drop due to viscosity and density Figure 6.2. Pressure drop and flow velocity of water in plastic-lined pipe Figure 6.3. Viscosity vs. minimum flow to produce turbulent flow Figure 604. Pressure drop for gas flow Figure 6.5. Pressure drop for gas flow Figure 6.6. Steam flow chart Figure 6.7. Fanning friction factor for pipe flow Figure 6.8. Sizing chart for pipe handling liquids in vertical down flow Figure 6.9. Basis for Lapp1e charts Figure Lapple charts for compressible flow Figure Flow curves for Parshall flumes Figure Composite sketch of small Parshall flume Figure Composite sketch of large Parshall flume Figure Curves showing relation between 1>1> 1>g, Rio and Rg for all flow mechanisms Figure Flow coefficient for square-edged orifices Figure Net expansion factor Y for compressible flow through nozzles and orifices Figure 7.1. Particle size classification Figure 7.2. Particle classification and useful collection equipment vs. particle size Figure 7.3. Efficiency curves for various types of dust-collecting equipment Figure 704. Cyclone sizing Figure 8.1. Flow of heat through tube walls Figure 8.2. Effect of velocity on heat transfer rates Figure 8.3. Heat supplied by 150 psig steam tracer Figure 804. Heat supplied by Dowtherm SR-l tracer Figure 8.5. Tube side heat transfer Figure 8.6. Shell side heat transfer curve for segmental baffles Figure 8.7. Film coefficients for water in tubes

10 FIGURES xiii Figure 8.8. Figure 8.9. Figure 8.1 O. Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 8,.22. Figure Figure Figure 9.1. Figure Figure Figure Figure Figure Figure Figure Figure Figure Tube side friction factors.... Tube side and return pressure drop per tube pass.... Shell side friction factors for low-finned and plain tubes.... LMTD correction factor F, 1-2 exchangers.... LMTD correction factor F, 2-4 exchangers.... Natural circulation boiling and sensible film coefficients.... Vertical thermosiphon reboiler connected to tower.. Condenser performance chart.... Condensing film coefficients Condensation in vertical tubes.... Condenser for material low in light ends.... Condensation curve for Figure Condenser for material with broad condensing curve. Condensation curve for Figure Service coefficient vs. outlet viscosity for natural gas and refinery liquid streams.... Required surface area for air-cooled heat exchangers as a function of the number of rows, overall U, approach, and cooling range.... Curve to find tt 2 /MMBtu/hr for example problem... Cyclone design and flow patterns.... Viscosities of liquids.... Viscosities of gases.... Refrigerant properties.... Specific heats of liquids.... Specific heats of gases at l-atm pressure.... Latent heats of vaporization.... Pump calculation sheet.... Viscosity correction chart ( gpm) Viscosity correction chart (100-10,000 gpm).... Figure Conventional relief valve Figure Balanced bellows relief valve Figure Comparison of a balanced bellows valve and a conventional valve Figure Cvs. specific heat ratio k Figure Variable or constant backpressure sizing factor Ky; 10% overpressure Figure Variable or constant backpressure sizing factor Ky; 20% overpressure

11 xiv FIGURES Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure vs. effective area factor Ka Typical steam ejector.... Capacity correction for molecular weight of entrained gas or vapor.... Capacity correction for temperature of entrained air or steam...,.... Effect of using incorrect steam pressure on steam ejectors.... Estimating steam requirements for ejectors.... Pressure control of ejectors.... Recommended disengaging height.... Drum size vs. holding time.... Segmental area available for liquid holding time.... General arrangement of mesh pad in horizontal vaporliquid separator.... Guide to ASME Boiler and Pressure Vessel Code, Section VIII, Division I.... ASME Code pressure vessel shell thickness chart

12 s 1.1. Power factors for agitators in turbulent flow Static Mixer unit specification table Estimating the number of mixer elements Viscosity correction factor K' Relative performance ratings of contacting devices for distillation columns Packing factors for tower packing Suggested fluid velocities in pipe and tubing Resistance of flanged elbows, tees, and bends in equivalent pipe length Resistance of screwed elbows, tees, and bends in 67 equivalent pipe length Resistance of valves in equivalent pipe length Resistance of eccentric and concentric reducers and sudden line size changes in equivalent pipe length Resistance of horizontal and vertical inlets and outlets in equivalent pipe length A. C v factors for Tufline valves B. Plug positions for 3-way Tufline valves C. Sizing formulas for Tufline valves Flow of water through Schedule 40 steel pipe Flow of air through Schedule 40 steel pipe Discharge from triangular notch weirs with end contractions Discharge from rectangular weirs with end contractions Dimensions and capacities of small Parshall measuring flumes Dimensions and capacities of large Parshall measuring flumes Flow mechanisms for two-phase flow Values of Martinelli functions with independent variable X Discharge of air through an orifice xv

13 XVI TABLES Locations of orifices and nozzles relative to pipe fittings Inside and outside film coefficient, hi and ho Fouling resistance, Fo and Fi Overall coefficients in typical petrochemical applications Thermal resistance of pipes and tubing Thermal resistance of glass-lined pipe Overall coefficients for platecoils Heat loss from storage tanks and product correction factors Thermal conductivities of some insulating materials Heat exchanger tube sheet layout count Jacketed glass-lined steel vessel heat transfer Typical glassed steel reactor dimensions Typical service coefficients TheB constant Layoutinformation for air-cooled exchangers Face velocities Chemical composition of selected metals Applications of various metals in the chemical industry.., Thermal conductivities of some building and insulating materials Thermal conductivities, specific heats, and specific gravities of metals and alloys Thermal conductivities of liquids Thermal conductivities of gases and vapors C p ICv ratios of specific heats of gases at l-atm pressure Specific heats of organic liquids Specific heats of miscellaneous materials Specific gravities and molecular weights of liquids Heats of vaporization of organic compounds Viscosities of liquids Viscosities of gases Coefficients of linear expansion -approximate values Thermodypamic properties of saturated steam Physical properties of Freon products Molecular diffusivities

14 TABLES xvii Dimensions and properties of steel pipe..., Dimensional data, plastic-lined pipe Kb factor for conventional valves in gas or vapor service Orifice sizes for relief valves Ksh superheat correction factors Air released from water under vacuum Pressure range for ejectors Estimated air leakage into equipment in vacuum service Volume of cylinders, in. diameter Volume of cylinders, ft diameter Approximate volume of heads Volume of partially filled horizontal cylinders Volume of partially filled heads on horizontal tanks Dimensions and properties of steel tubing Values for R dv General notes, ASME code lb flange pressure-temperature ratings lb flange pressure-temperature ratings