Petroleum Refining Design and Applications Handbook. A. Kayode Coker

of the process design engineer. The functions of these roles are used in various chapters of volumes 2, 3 and 4 of these volume series. Other pertinent functions in this chapter are flowsheets involving a block diagram, process flow (PFD) diagram and process and instrumentation (P & ID) diagram, computer-aided flowsheet design, symbols and basic engineering and front-end engineering design (FEED). Chapter 15 is on fluid flow in process piping, showing the scope, the basis for incompressible and compressible fluids, oil systems piping, pressure drop in process lines, including fittings, resistance of valves, water hammer, two-phase liquid and gas flows in process piping; application of UniSim design PIPESYS, mitigating pipeline hazards, pipeline safety and safety incidents related with pipework and materials of construction and design for safer piping. This chapter further provides the root causes, findings and recommendations of these incidents in the refinery and chemical plants ensuring that lessons are learned and thus preventing further deaths; Chapter 16 reviews pumping of liquids, centrifugal pump selection, hydraulic characteristics for centrifugal pumps, net positive suction head and requirement for liquid’s saturation with dissolved gases, pump cavitation, affinity laws, centrifugal pump efficiency, rotary pumps, reciprocating pumps, screw pumps, operating philosophy, troubleshooting and checklist for centrifugal pumps, pumps reliability, root causes of pump failures and their impact, cases studies of pump failures in the refinery, their root causes, findings and recommendations. Process safety management involving mechanical integrity and management of change (MOC). Chapter 17 describes compression equipment with specification guides, general application guide, and performance consideration, hydrogen use in the refinery, and UniSim design case studies. The chapter further describes various compressor types, advantages and disadvantages, probably causes and troubleshooting as well as process safety incidents involving compressors’ malfunctions. Furthermore, the chapter describes integrally geared compressors that have wide application in carbon dioxide (CO2) service for enhanced oil recovery (EOR) with an added benefit to the environment, as nearly all of the injected CO2 is permanently sequestrated in the depleted oil fields long after these fields have ceased operation. Appendix D provides construction commissioning start-up checklists of rotary equipment such as pumps, compressors, and other equipment such as blowers, fans and mixers.

      Acknowledgments

      This project is the culmination of five years of research, collating relevant materials from organizations, institutions, companies and publishers, developing Excel spreadsheet programs and computer programs; using Honeywell’s UniSim steady state simulation programs and providing the majority of the drawings in the text.

      Sincere gratitude to Honeywell Process Solutions for granting permission to incorporate the use of UniSim Design simulation and many other suites of software programs in the book. I express my thanks to Dr. Jamie Barber of Honeywell Process Solutions for his friendship and help over many years of using the UniSim software. To Mr. Ahmed Mutawa formerly of SASREF Co., Saudi Arabia for developing the Conversion Table program for the book.

      Many organizations, institutions and companies as Gas Processor Suppliers Association (GPSA), USA, Honeywell Process Solutions, Saudi Aramco Shell Refinery Co., (SASREF), Absoft Corporation, USA., American Institute of Chemical Engineers, The Institution of Chemical Engineers, U.K., Chemical Engineering magazine by Access Intelligence, USA., Hydrocarbon Processing magazine have readily given permission for the use of materials and their release for publication. I greatly acknowledge and express my deepest gratitude to these organizations.

      I have been privileged to have met with Phil Carmical, Publisher at Scrivener Publishing Co., some twenty years ago. Phil initiated the well-known Ludwig’s project at the time during his tenure at Gulf Publishing Co., and Elsevier, respectively. His suggestions in collaborating on these important works some seven years ago were timely to the engineering community, as I hope that these works will be greatly beneficial to this community world-wide. I’m deeply grateful to Phil for agreeing to collaborate with me, his suggestions and assistance since. It is my believe upon completing this aspect of the project that the book will save lives in the refinery industry.

      I also wish to express my thanks to the Wiley-Scrivener team: Kris Hackerott-Graphics Designer, Bryan Aubrey – Copy editor, Myrna Ting – Typesetter and her colleagues. I am truly grateful for your professionalism, assistance and help in the production of this volume.

       Finally,

       Bow down in humility before the Greatness of God,

       whose Love is never-ending, and who sends us his help at all times.

       He alone is Life and the Power and the Glory for ever and ever.

       A. Kayode Coker

      13 Rules of Thumb—Summary

      13.0 Introduction

      An engineering Rule of Thumb is an outright statement regarding suitable sizes or performance of equipment that avoids all requirements for extended calculations. These are safely applied by engineers who are substantially familiar with the topics. However, such rules should be of value for approximate design and cost estimation, and should not provide the inexperienced engineer with perspective and a foundation where detailed and computer-aided results can be determined.

      Experienced engineers often know where to find information and how to make accurate calculations; they also retain a minimum body of information in mind, which is made up largely of shortcuts and heuristics. The compilation below may fit into such a minimum body of information that boosts to the memory or extension in some instances into less often encountered areas.

      COMPRESSORS, FANS, BLOWERS, AND VACUUM PUMPS

      1 1. Fans are used to raise the pressure by about 3% [12 in. (30 cm) water], blowers raise to less than 2.75 barg (40 psig), and compressors to higher pressures, although the blower range is commonly included in the compressor range.

      2 2. For vacuum pumps use the following:Reciprocating piston typedown to 133.3 Pa (1 torr)Rotary piston typedown to 0.133 Pa (0.001 torr)Two lobe rotary typedown to 0.0133 Pa (0.0001 torr)Steam jet ejectors1 stage down to 13.3 k Pa (100 torr)3 stage down to 133.3 Pa (1 torr)5 stage down to 6.7 Pa (0.05 torr)

      3 3. A three-stage ejector needs 100 kg steam/kg air to maintain a pressure of 133.3 Pa (1 torr).

      4 4. In-leakage of air to evacuated equipment depends on the absolute pressure (torr) and the volume of the equipment, V in m3 (ft3), according to W = kV2/3 kg/h (lb/h), with k = 0.98 (0.2) when P > 90 torr, k = 0.39 (0.08) when P is between 0.4 and 2.67 kPa (3 and 20 torr), and k = 0.12 (0.025) at p less than 133.3 Pa (1 torr).

      5 5. Theoretical adiabatic horsepower where T1 is inlet temperature in Rankine, R = °F + 460 and a = (k − 1)/k, k = Cp/Cv. Theoretical reversible adiabatic power = mɀ1RT1[({P2/P1}a − 1)]/a, where T1 is inlet temperature, R = Gas Constant, ɀ1 = compressibility factor, m = molar flow rate, a = (k − 1)/k and k = Cp/Cv. Values of °R = 8.314 J/mol K = 1.987 Btu/lb mol R = 0.7302 atm ft3/lb mol° R.

      6 6. Outlet temperature for reversible adiabatic process

      7 7. To compress air from 37.8° C (100°F), k = 1.4, compression ratio = 3, theoretical power required = 62 hp/million ft3/day, outlet temperature 152.2°C (306°F).

      8 8. Exit temperature should not exceed 167–204° C (350–400° F); for diatomic gases (Cp/Cv = 1.4), this corresponds to a compression ratio of about 4.

      9 9.