LIBRO AZUL.pdf

CONTROL VALVE SOURCEBOOK

REFINING

Copyright 2004 Fisher Controls International LLC All Rights Reserved.

easy-e, edisc, eplug, Fisher, NotchFlo, POSI-SEAL, WHISPER TRIM, and VEE-BALL aremarks owned by Fisher Controls International LLC, a business of Emerson Process Manage-ment. The Emerson logo is a trademark and service mark of Emerson Electric Co. All othermarks are the property of their respective owners.

This publication may not be reproduced, stored in a retrieval system, or transmitted in wholeor in part, in any form or by any means, electronic, mechanical, photocopying, recording orotherwise, without the written permission of Fisher Controls International LLC.

Emerson Process Management gratefully acknowledges the contribution made to this bookby Key Control, Inc. and the contributions made by Emerson Process Management em-ployees:

Justin E. Trawny Refining-Petrochemical Industry Manager (Fisher Valve Division)Tim Olsen Process & Performance Consultant-Advanced Applied Technologies (Process Solutions Division)

Printed in U.S.A., First Edition

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Table of Contents

Contents at a Glance

Introduction ix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Furnace, Chapter 1 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Distillation Column, Chapter 2 21. . . . . . . . . . . . . . . . . . . . . . . . . .

Gas Plant, Chapter 3 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Crude Distillation, Chapter 4 41. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Vacuum Distillation, Chapter 5 51. . . . . . . . . . . . . . . . . . . . . . . . . .

Delayed Coking Unit, Chapter 6 61. . . . . . . . . . . . . . . . . . . . . . . . .

Hydrotreater, Chapter 7 71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Hydrocracker, Chapter 8 81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Catalytic Reformer Unit, Chapter 9 91. . . . . . . . . . . . . . . . . . . . . .

Fluid Catalytic Cracker, Chapter 10 101. . . . . . . . . . . . . . . . . . . . .

Alkylation Unit, Chapter 11 111. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Amine Unit, Chapter 12 121. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sulfur Recovery Unit, Chapter 13 131. . . . . . . . . . . . . . . . . . . . . . .

Blending Unit, Chapter 14 141. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Complete Contents

Refinery Control ValvesIntroduction ix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Other Names x. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Process Descriptions xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Valve Selection xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Process Drawing xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Problem Valves xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Abbreviations xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 FurnaceOther Names 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Feed Valve 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Gas Valve 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 Distillation ColumnOther Names 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Feed Valve 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reflux Valve 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bottom Product Valve 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pressure Control Valve 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overhead Product Valve 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reboil Valve 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 Gas PlantOther Names 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Lean Sponge Oil Valve 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absorber/Deethanizer Reboil Valve 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Overhead Valve 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sponge Absorber Overhead Valve 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absorber/Deethanizer Bottom Product Valve 38. . . . . . . . . . . . . . . . . . . . . . Absorber Lean Oil Valve 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Bottom Product Valve 310. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Reflux Valve 311. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Reboil Valve 312. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Overhead Product Valve 313. . . . . . . . . . . . . . . . . . . . . . . . . . C3/C4 Splitter Bottom Product Valve 314. . . . . . . . . . . . . . . . . . . . . . . . . . . . C3/C4 Splitter Reflux Valve 315. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C3/C4 Splitter Overhead Product Valve 316. . . . . . . . . . . . . . . . . . . . . . . . . C3/C4 Splitter Reboil Valve 317. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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4 Crude DistillationOther Names 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Feed Valve 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pump-Around Valve 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Valve 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bottoms Valve 46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reflux Valves 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Stripping Steam Valve 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripping Steam Valve 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripper Bottoms (Product) Valve 410. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overhead Pressure Control Valve 411. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overhead Product Valve 412. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 Vacuum DistillationOther Names 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Feed Valve 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Valve 54. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pump-Around Valve 55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripping Steam Valve 56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vacuum Resid Valve 57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripper Bottoms (Product) Valve 58. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gas Oil Valve 59. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripping Steam Valve 510. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6 Delayed Coking UnitOther Names 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Decoke Water Valve 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decoke Steam Valve 64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unit Feed Valve 65. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drum Decoke Block Valve 66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drum Switch Valve 66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Valve 67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Furnace Feed Valve 68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Pump-Around Valve 69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Reflux Valve 610. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Heavy Gas Oil Product Valve 611. . . . . . . . . . . . . . . . . . . . . . Fractionator Stripper Steam Valve 612. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Light-Ends Product Valve 613. . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Light Gas Oil Product Valve 614. . . . . . . . . . . . . . . . . . . . . . . . Fractionator Naphtha Valve 615. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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7 HydrotreaterOther Names 71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 73. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Unit Feed Valve 73. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Valve 74. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recycle Hydrogen Valve 75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reactor Hydrogen Valve 76. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Separator Overhead Valve 77. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Makeup Hydrogen Valve 78. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recycle Purge Valve 79. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripper Reflux Valve 710. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripper Bottoms Valve 711. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripper Light-Ends Valve 712. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stripper Naphtha Valve 714. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reactor Let-Down Valve 715. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hot and Cold High-Pressure Separator Let-Down Valve 716. . . . . . . . . . .

8 HydrocrackerOther Names 81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 83. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Feed Valve 83. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Valve 84. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recycle Hydrogen Valve 85. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reactor Hydrogen Valve 86. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . High-Pressure Separator Valve 87. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Low-Pressure Separator Valve 88. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Makeup Hydrogen Valve 89. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recycle Purge Valve 810. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Pump-Around Valve 811. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Bottom Valve 812. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Reflux Valve 813. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Heavy Naphtha Valve 814. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Distillate Valve 815. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Vent Gas Valve 816. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Light Naphtha Valve 817. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . High-Pressure Separator Let-Down Valve 818. . . . . . . . . . . . . . . . . . . . . . . Low-Pressure Separator Let-Down Valve 818. . . . . . . . . . . . . . . . . . . . . . .

9 Catalytic Reformer UnitOther Names 91. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 91. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 93. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Feed Valve 93. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Valve 94. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recycle Hydrogen Valve 95. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Separator Vapor Valve 96. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Net Hydrogen Valve 97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Separator Liquid Valve 98. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stabilizer Reboil Valve 99. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stabilizer Reflux Valve 910. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stabilizer Reformate Valve 911. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stabilizer Vent Gas Valve 912. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stabilizer Light-Ends Valve 914. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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10 Fluid Catalytic CrackerOther Names 101. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 101. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 103. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Air Valve 103. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Feed Valve 104. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Valve 105. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flue Gas Valve 106. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regenerated Catalyst Valve 107. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spent Catalyst Valve 107. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Pump-Around Valve 108. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Slurry Recycle Valve 109. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Reflux Valve 1010. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator LCO (Light Cycle Oil) Product Valve 1011. . . . . . . . . . . . . . . Fractionator HCO (Heavy Cycle Oil) Product Valve 1012. . . . . . . . . . . . . . Fractionator Reboil Circuit Valve 1013. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Wet Gas Valve 1014. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fractionator Distillate Valve 1015. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11 Alkylation UnitOther Names 111. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 111. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 113. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Feed Valve 113. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Makeup Acid Valve 114. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Caustic Wash Valve 115. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water Wash Valve 116. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Depropanizer Bottom Valve 117. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Depropanizer Reflux Valve 118. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DIB (Deisobutanizer) Isobutane Valve 119. . . . . . . . . . . . . . . . . . . . . . . . . . Makeup Isobutane Valve 1110. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Depropanizer Reboil Valve 1111. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DIB Reboil Valve 1112. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Depropanizer Propane Product Valve 1113. . . . . . . . . . . . . . . . . . . . . . . . . DIB Reflux Valve 1114. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DIB Bottom Valve 1115. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Alkylate Valve 1116. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Reflux Valve 1117. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Butane Valve 1118. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Debutanizer Reboil Valve 1119. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12 Amine UnitOther Names 121. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 121. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 123. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Scrubber Bottom Valve 123. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scrubber Lean Amine Valve 124. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Amine Makeup Valve 125. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regenerator Bottom Recycle Valve 126. . . . . . . . . . . . . . . . . . . . . . . . . . . . Regenerator Reflux Valve 127. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regenerator Bottom-to-Storage Unit Valve 128. . . . . . . . . . . . . . . . . . . . . . Regenerator Reboil Valve 129. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regenerator Sulfur Gas Valve 1210. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vii

13 Sulfur Recovery UnitOther Names 131. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 131. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 133. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fuel Gas Valve 133. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oxygen Valve 134. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Main Air Valve 135. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trim Air Valve 136. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid Gas from Amine Valve 137. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sour Gas from SWS (Sour Gas Stripper) Valve 138. . . . . . . . . . . . . . . . . . Reheater Steam Valve 139. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14 Blending UnitOther Names 141. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 141. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valves 143. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Component Valve 143. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ix

Refinery Control Valves

Introduction

The petroleum refining industry is an industrythat is most vital to our modern global economy.Almost constantly, you are in close contact withproducts that once were distilled through col-umns like those shown above. Some of thesematerials and products are so important thattheir rapidly fluctuating market values are re-ported every day on television, radio, Internet,and newspapers.

The products go through many phases fromcrude oil and other raw materials to the finalproducts you use every day. On the followingpage is a chart showing the raw materials, someof the intermediate petroleum product phases,and some of the final products that reach you asa consumer. Many of the products on the nextpage are further processed and become part oftoo many items to mention.

The products are all processed and made readyfor the market in refineries. Efficient operation ofrefineries has a tremendous impact on profit,final consumer price, and wise use of limitedresources. Efficient refinery operation dependson well-planned and well-executed control strat-egies, responsive control systems, and tough,reliable control valves.

This sourcebook is a primer on the use of con-trol valves in many refining processes. It is in-tended to help you:

Understand the types of refining processes,

Learn where control valves are typicallylocated within the process,

Identify the operational problems that mightbe caused by poor valve performance,

Identify Fisher valves that are commonlyused for the applications in a refinery.

x

Product Streams in the Refining Industry(Reprinted by Permission of HYDROCARBON PROCESSING Magazine, Gulf Publishing Company, Houston, Texas)

RAW MATERIALS INDUSTRIAL AND CONSUMER PRODUCTSINTERMEDIATE PRODUCTS

A standard format is used to present the infor-mation on each refining process. The informa-tion provided is:

Other commonly-used names for the de-scribed process

The basis (feed rate) for the example pro-cess

A short description of the process

A list and description of each important pro-cess valve in the unit

A functional drawing of the process

Typical process conditions

Names of Fisher valves that can be con-sidered for each process

Potential process impacts and special con-siderations for each valve

Other NamesIt is not possible to make an all-inclusive list ofcommonly-used process names. Many refinerieshave developed specific process names basedon local preference or the preferences of thelicensor or designer that developed the process.

xi

Process Descriptions

Many processing units within a refinery containfurnaces and distillation columns, which makesthese pieces of equipment and their operationfairly universal. The valve requirements for theseunits are presented in Chapters 1 and 2, respec-tively, and are not repeated in the chapters thatfollow.

Chapters 3 through 14 discuss refining pro-cesses, with the valve information presented ineach chapter applying directly to the specificprocess being described.

Valve Selection

The information presented in this sourcebook isintended to assist in understanding the controlvalve requirements of general refining pro-cesses.

Since every refinery is different in its unit make-up and the technologies it utilizes, the controlvalve requirements and recommendations pre-sented by this sourcebook should be consideredas general guidelines.

The information in this sourcebook is intended toassist with understanding general refining pro-cess requirements and general control valveconsiderations.

Under no circumstances should this informationalone be used to select a control valve withoutensuring that the proper valve construction isidentified for the application and process condi-tions.

All valve considerations should be reviewed withyour Fisher sales office or representative as partof any valve selection or specification activity.

Control Valves

Typical Control Valve (easy-e Valve)

W8119

Valves described within a chapter are labeledand numbered corresponding to the identifica-tion used in the process flow chart for that chap-ter. The order in which they are discussed isfrom left-to-right and top-to-bottom.

If a valve is controlling feed, intermediate or finalproduct streams, the U.S. dollar value of thatstream (as recorded at the time of sourcebookpublication) and typical feed rate are provided.The valve function also is described, and a spec-ification section gives added information on pro-cess conditions, names of Fisher valves that canbe considered, process impact of the valve andany special considerations.

xii

Process Drawing

Typical Process Drawing

E0922

The process drawing within each chapter showsmajor equipment items, their typical placementwithin the processing system and process flowdirection. Utilities, pumps and most heat ex-changers are not shown. Valves are numberedin sequence from left-to-right and top-to-bottom.

Problem ValvesOften there are references to valve-causedproblems or difficulties. The litany of problemsincludes valve stickiness caused by excessivefriction (called stiction), excessive play in valve-to-actuator linkages (typically in rotary valves)that causes deadband, excessive valve stempacking leakage, and valve materials that areincompatible with the flowing medium. Any oneor a combination of these difficulties can affect

process quality and throughput, with a resultingnegative impact on refinery profitability.

Many of these problems can be avoided or mini-mized through proper valve selection. Consider-ation should be given to valve style and size,actuator capabilities, analog vs. digital instru-mentation, materials of construction and the like.Although not being all-inclusive, the informationthat this sourcebook provides should facilitatethe valve selection process.

Abbreviations

BBL Barrels

BPD Barrels per day

CCR Continuous catalytic reformer

DIB Deisobutanizer

FCC Fluid catalytic cracker

Gal Gallons

GPM Gallons per minute

HCO Heavy cycle oil

HDS Hydrodesulfizer

HVGO Heavy vacuum gas oil

LCO Light cycle oil

LVGO Light vacuum gas oil

LPG Liquified petroleum gas

MBPD Thousand barrels per day

MCF Thousand cubic feet

MCFD Thousand cubic feet per day

MMCF Million cubic feet

MMCFD Million cubic feet per day

MGPY Thousand gallons per year

MLB Thousand pounds

MLBD Thousand pounds per day

SRU Sulfur recovery unit

SWS Sour water stripper

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Chapter 1

Furnace

Other NamesHeater, cracking furnace, steam cracker, steamre-former, reboiler heater

DescriptionFurnaces are used to heat process feed material.Heat is created by burning fuel in burners on thefloor and/or walls of the furnace. There are manydifferent types of fuel that can be used by a furnace,such as natural gas, liquified petroleum gas (LPG),refinery waste gas and fuel oil.

The process feed stream to a furnace is usuallybroken into multiple tube passes to improve heattransfer. The most common configurations are two-and four-pass furnaces. The passes are recombinedinto a single effluent stream after they exit thefurnace.

The outlet temperature of a furnace is normallydictated by the requirements of a downstreamprocess, usually a reactor or distillation column.Adjusting the amount of fuel burned controls theoutlet temperature.

In some cases, the furnace will provide enough heatto crack the feed stream thermally from largehydrocarbon molecules to smaller molecules. Inthese cases, the outlet temperature is used tocontrol the amount of cracked components in theeffluent stream.

12 FURNACE

Typical Furnace

FURNACE 13

Control Valves

easy-e ValveW8119

W2966 W3962

Feed Valve Function (#1, #2, #3, #4)Feed valves are usually set up as flow-control loops.They are configured to fail open so that a valvefailure will protect the furnace radiant section tubes.If a radiant tube loses flow or has insufficient flow,the tube can quickly become so hot that the metalcan melt. This can have disastrous consequences,as most process feeds make excellent fuels. Afurnace can be destroyed very quickly if a rupturedtube is dumping into the firebox of the furnace.

Problem valves can lead to difficulties withcontrolling the outlet temperature of the furnaces.Also, many process feeds slowly build layers of cokeon the inside of the radiant tubes. Coking is a

non-linear reaction, and in some processes even afew extra degrees of temperature can lead toexcessive coke buildup. If a flow valve is alternatelyprovided too much and then too little flow, thetemperature will also swing and will usually lead toexcessive coke buildup. This will shorten the furnacecycle time between decoking procedures, which willnormally require the process unit downstream toshutdown.

Feed valves can easily be bypassed whennecessary. A combination of the measured flow andany available pass temperatures can be used toregulate the bypass valve.

Feed Valve Specification (#1, #2, #3, #4)

Process MediaMedia Pressure Range Temperature Range

Heavier gas oilNaphtha

Dependent on process design

Valve Types

Heavy duty general purpose globe valves easy e valvesUnbalanced, cageless EZ

Heavy-duty, general-purpose globe valves easy-e valvesBalanced with graphite cage-plug seal ED

Process Impact

Control is critical to maintaining integrity ofinternal furnace tubes, such as preventing cokelay-down.

Valve performance is critical to overall reliabilityof furnace.

Critical to furnace safety; process fluid flow isrequired at all times through the tubes while thefurnace is firing.

Special Considerations

Sour feed stocks might require NACE trimmaterials

14 FURNACE

Fuel Gas Valve Function (#5)

easy-e Valve Vee-Ball Valve

W8119

W8192

W7435

Depending on the furnace service and configurationthis valve will normally be part of a loop that controlseither the fuel flow or pressure. These valves arespecified as fail closed so that a control loop failurewill not allow excessive fuel to be dumped into a hotfurnace. A fuel valve failure will almost always shutdown the processing unit downstream. Althoughmany fuel valves have bypass circuits, refineryoperations personnel are usually reluctant to run afurnace on bypass for any significant time becauseof safety concerns.

The preferred control loop configuration for the outlettemperature is a cascade to the set point of the loopcontrolling the fuel valve. Many furnaces will be setup such that the temperature control loop directly

manipulates the fuel valve. This direct connectionusually provides control performance that is inferiorto a cascade configuration. It is extremelysusceptible to any valve dead band such as thatcaused by a sticking valve. This can be detected byexcessive oscillation in the outlet temperature.

When the fuel valve is manipulated by thetemperature loop or by a flow control loop, there willoften be a pressure control valve upstream of thefuel valve. This valve will also fail closed and willhave the same consequences as a failure of the fuelvalve. However, with this configuration, Refineryoperations personnel will be more willing to run afuel valve in bypass as they still have a way toquickly shut off the fuel in an emergency.

Fuel Gas Valve Specification (#5)


Natural gas-fuel gas mixtureFuel oil with atomizing steam


Valve TypesUnbalanced, cageless EZ

Heavy-duty, general-purpose globe valves easy-e valves Balanced with graphite cage-plug seal EDHeavy duty, general purpose globe valves easy e valvesBalanced with polymer cage-plug seal ET

High-capacity, high-rangeability V-notchVee Ball valves

Class 150 V150High capacity, high rangeability V notchrotary ball valves Vee-Ball

valvesClass 300 V300

Process Impact

Performance is critical to controlling furnacetemperature.

Performance is critical to reducing energy costsassociated with furnace.


Potential for acidic fouling gases (for example,H2S, HCL)

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Chapter 2

Distillation Column

Other NamesTower, stripper, stabilizer, splitter, demethanizer,deethanizer, depropanizer, debutanizer, DIB(deisobutanizer) tower, precut tower

DescriptionDistillation columns are a basic building block forevery refinery. The objective for any distillationcolumn is to separate a feed stream intolight-component and heavy-component productstreams.

The distillation process relies on the relative volatilitybetween the components that make up the feedstream. The high-volatility (lighter) components willboil at a lower temperature than will the low-volatility(heavier) components. Therefore, when heat isadded to the column through a bottom reboiler, thelighter materials are vaporized and rise to the top ofthe column. The overhead vapors are cooled untilthey condense and become a liquid again.

The efficiency of the distillation depends on theamount of contact between the vapor rising and theliquid falling down through a column. Therefore,

some of the overhead liquid product is sent back(refluxed) to the top of the column. Increasing thereflux will improve the purity of the overheadproduct. However, it also requires more heat fromthe reboiler to re-vaporize the lighter components inthe reflux stream. The operation of a distillationcolumn is a balancing act between product purityand energy use.

If the amount of vapor and liquid traveling throughthe column (often referred to as traffic) becomestoo great, the column can flood. Too much refluxflow or too much reboil heat resulting in too muchvapor, (or both) can cause flooding. When floodingoccurs, the efficiency of the distillation column isdramatically reduced, with corresponding drops inproduct purities.

22 DISTILLATION COLUMN

Typical Distillation Column

DISTILLATION COLUMN 23

Control Valves

Feed Valve Function (#1)

easy-e Valve Vee-Ball ValveW8119

W8192

W7435

Feed valves are usually set up as flow or levelcontrol loops. An upstream unit or process oftencontrols the valve.

Unstable feed flow will make the distillation columndifficult to control. A problem valve will often causethe feed flow to oscillate. As a result, the column willalternate between too little and too much reboil heat.Depending on the size and number of trays in the

column, the effect of a swing in the feed will takeanywhere from several minutes to more than anhour to reach the ends of the column. Sometimes,the reboil and reflux controls will amplify the swings.The final result is that meeting product purity targetsbecomes more difficult. Refinery operationspersonnel will normally respond by over-purifying theproducts, wasting energy to compensate for theproblematic feed control valve.

Feed Valve Specification (#1)


Primarily reactor effluent Dependent on process design Dependent on material being distilled

Valve Types

Lower flow rates (line sizes Heavy duty general purpose globeUnbalanced, cageless EZ

Lower flow rates (line sizes4 inches and smaller)

Heavy-duty, general-purpose globevalves easy-e

valves Balanced with graphite cage-plug seal ED4 inches and smaller) valves easy e valvesBalanced with polymer cage-plug seal ET

Higher flow rates (line sizes High-capacity, high-rangeability V-notchVee Ball valves

Class 150 V150Higher flow rates (line sizes6 inches and larger)

High capacity, high rangeability V notchrotary ball valves Vee-Ball


Process Impact

Minimal impact to process


Flashing might be present depending on theprocess variables.


Reflux Valve Function (#2)


W8192

edisc Valve

W6234

The reflux valve is typically either a flow or columntemperature-control loop. It is used to adjust thepurity of the overhead product. The higher the refluxrate, the purer the overhead product will become.However, raising the reflux rate also will require

more reboil heat and eventually will flood the tower.

A poorly operating reflux valve will have the sameeffects as a bad feed valve. Product purities willoscillate, and the column will be difficult to control.

Reflux Valve Specification (#2)


Dependent on distillation process Dependent on process design Dependent on material being distilled

Valve Types

High-capacity, high-rangeability V-notch rotaryVee Ball valves

Class 150 V150High capacity, high rangeability V notch rotaryball valves Vee-Ball


edisc valvesThrough 12 inches 8560


High-performance butterfly valves Class 150, 300 through 12 inches A41High performance butterfly valves

POSI-SEAL valves Larger sizes A31APOSI SEAL valvesHigh pressure A11

Unbalanced, cageless EZ

Balanced with graphite cage-plug seal EDHeavy-duty, general-purpose globe valves easy-e valves Balanced with polymer cage-plug seal ETy y g g y

Larger sizes; expanded ends; balanced orunbalanced

EW

Process Impact Critical to maintaining vapor/liquid balance in

the column, ultimately affecting the efficiency of thecolumn


Typically none


Bottom Product Valve Function (#3)

Vee-Ball Valve

W8192W5791

eplug Valve

W5793

The bottom product valve is typically used to controlthe level in the bottom of the column. It normally has

no effect on column operation unless it causes thelevel to change quickly and dramatically.

Bottom Product Valve Specification (#3)



Valve Types

High capacity high rangeability V notch rotary ball valves Vee Ball valvesClass 150 V150

High-capacity, high-rangeability V-notch rotary ball valves Vee-Ball valvesClass 300 V300

General and severe service eccentric rotary plug valves eplug valvesHigh capacity, rugged CV500

General- and severe-service eccentric rotary-plug valves eplug valvesMore rugged construction V500

Process Impact

Dependent on downstream destination


Could encounter higher viscosity materials,sludge and process media with entrained particles

Ball valves or eccentric plug valves mightrequire Stellite (Alloy 6) or ceramic trim materials.

Low-flow, clean fluids or small line-sizeapplications could use globe valves.


Pressure Control Valve Function (#4, #4a)

easy-e Valve Vee-Ball ValveW8119 W8192

W3162

The pressure control valves are used to control thecolumn pressure. Higher column pressures will yieldbetter product purities, but require more energy tooperate. Normal operating procedure is to minimizethe pressure to lower energy costs while maintainingproduct specifications. There is a low limit becauselower pressures reduce the amount of vapor/liquidtraffic the column can handle and can make it morelikely to flood.

The simplest way to control pressures is tocontinuously vent gas from the system (valve #4).This sizing of this valve is critical. If the valve is toolarge, a small valve movement will cause a largepressure swing. If the valve is too small, thepressure response will be very sluggish. It is likelythat a valve that is too small will operate fromcompletely closed to completely open. In eitherscenario, oscillating column pressure and difficultcolumn control result. A sticking pressure controlvalve presents the same problem. A sticking valve isa common concern on vent gas service because thevalve packing is normally tight to prevent fugitiveemissions.

Many distillation columns also use what is known asa hot vapor bypass valve (#4a) to control pressure.In these instances, some of the hot overhead vaporsare bypassed around the overhead condenser heatexchanger. The amount of bypass will control thepressure. This eliminates the constant venting of

process gas, which usually goes to a low-valuerefinery waste fuel gas system. Unfortunately, thepressure response on a hot vapor bypass valve isnormally very sluggish due to slow process responsetime. Like the vent gas valve, this valve is a concernfor fugitive emissions, and the packing is likely to betight. A sticking valve causes wide, slow oscillationsin column pressure, and product purities likewiseswing widely and slowly. The response of refineryoperations personnel is usually to over-purify.

A majority of columns with hot-vapor bypass valvesalso utilize a vent gas valve. In these cases, a singlepressure control loop manipulates both valves. Atlower pressures, the hot vapor bypass valve is used.As the pressure rises, there is a transition pointwhere the hot vapor bypass valve closes fully andthe vent gas valve starts to open.

At high pressures, the vent gas valve controls thepressure. This configuration often leads to pressurecontrol problems, as the hot vapor bypass and ventgas valves have different control characteristics.Also, it is unlikely that one valve will close preciselyat the same time the other valve opens. If thecolumn is constantly making a transition betweenusing the hot vapor bypass and vent gas valves, thepressure will normally oscillate. This is a tuningrather than a valve problem, but it should be kept inmind for column design or valve resizing.


Pressure Control Valve Specification (#4, #4a)








Process Impact

Controls the back pressure to the distillationcolumn and is very important in controlling thestability of the tower. Many columns use traytemperature to control overhead composition, thusstable pressure is required to ensure thattemperature changes reflect composition changesnot pressure changes.


Packing on these valves is important to reducefugitive emissions.

Consider using special materials on valve #4 toaddress acid gas environment.


Overhead Product Valve Function (#5)


W8192

W7435

The overhead product valve is typically used tocontrol the level in the overhead receiver. It normally

has no effect on column operation unless it causesthe level to change quickly and dramatically.

Overhead Product Valve Specification (#5)




Heavy duty, general-purpose globe valves easy-e valves Balanced with graphite cage-plug seal EDHeavy duty, general purpose globe valves easy e valvesBalanced with polymer cage-plug seal ET




Process Impact Typically no critical impact



None


Reboil Valve Function (#6)

easy-e ValveW8119

W2966 W3162 W0451

The reboil valve controls the amount of heat put intothe column by the reboiler. In many cases, steam isused as a heat source. The service is very clean,and fugitive emissions are not a concern. Steamvalves are usually very reliable. However, aproblematic valve will make the column difficult tocontrol precisely. This will be especially true if thecolumn feed is subject to frequent changes.

Not all reboilers use steam as a heat source. Tosave energy, many refineries have integrated theirunits so that higher-temperature process streamsare used to provide heat for lower-temperatureprocesses. In these cases, the reboil valve will foulmore easily and might create fugitive emissionconcerns.

Reboil Valve Specification (#6)


Steam Dependent on process design, typically 10.3bar (150 psig) saturated steam

Dependent on material being distilled



Process Impact This valve is important because it drives the

vapor back up through the column. Vapor throughthe column affects column efficiency. Reboiler steamwill have a direct effect on overhead reflux flow.


Consideration of materials for steam application

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Chapter 3

Gas Plant

Other NamesLight ends unit, sat. (saturated) gas plant

DescriptionMost reactive processes in a refinery create light endmaterial in addition to the desired products(gasoline, kerosene, diesel, and so on). These lightends include hydrogen, methane, ethylene, ethane,propylene, propane, and various butanes andbutenes. Light ends are usually a low-value processstream, and are often used as fuel gas for processheaters. However, if enough light-end materials areproduced, there is economic incentive to separatethe light ends into component streams. The exactproduct streams will depend on refinery needs aswell as any potential external marketingopportunities.

Some cracking units produce enough light ends thata gas plant is built specifically as part of the unit.(Delayed cokers and fluid catalytic crackers are unitsthat usually have an integral gas plant.) In othercases, gas plants are built to handle the combinedlight ends of several process units.

Almost all valves in a light-ends gas plant are apossible source of fugitive emissions. Therefore, it isvery likely that the valve packing will be kept verytight. This can lead to excessive control valve deadband. Packing selection might play a critical role invalve performance for this type of service.

The example used for this section is a typical FCCgas plant. The light ends that come from the FCCfractionator overhead are separated by this plant into

fuel gas (hydrogen, methane, and ethane), C3(propylene and propane), C4 (butenes and butanes),and naphtha.

As fractionator overheads enter an absorber/deethanizer, hydrocarbons lighter than C3 leave asoverheads to the sponge absorber. The spongeabsorber uses heavy oil to reclaim any C3 thatcomes overhead from the deethanizer. Theremaining gas is sent to the refinery fuel gas system.The C3 and heavier components leave as bottoms tothe debutanizer.

In the debutanizer, C3 and C4 are separated fromlight naphtha. The C3 and C4 leave as overheads tothe C3/C4 Splitter. The naphtha leaves as bottoms toeither blending or a downstream processing unit.

The C3/C4 splitter separates the debutanizeroverheads into an overhead C3 stream and a bottomC4 stream.

32 GAS PLANT

Typical Gas Plant

GAS PLANT 33

Control Valves

Lean Sponge Oil Valve Function (#1)

easy-e Valve Vee-Ball Valve

W8119

W8192W3162

This valve controls the flow of lean, heavy naphthafrom the FCC (fluid catalytic cracker) fractionator tothe sponge oil tower, which absorbs any leftover C3and heavier materials from the absorber/deethanizeroverheads. The rich sponge oil is returned to the

fractionator. The consequences of bad valveperformance are that higher value, heaviercomponents might escape to the lower value fuelgas system.

Lean Sponge Oil Valve Specification (#1)


Lean, heavy naphtha from the FCCfractionator to sponge oil tower

Dependent on process design Dependent on process media


Heavy-duty,general-purpose globe valves easy-e valves Balanced with graphite cage-plug seal EDHeavy duty,general purpose globe valves easy e valvesBalanced with polymer cage-plug seal ET

High capacity high rangeability V notch rotary ball valves Vee Ball valvesClass 150 V150

High-capacity, high-rangeability V-notch rotary ball valves Vee-Ball valvesClass 300 V300

Process Impact Poor valve control can allow higher value,

heavier components to escape to the lower valuefuel gas system.


None

34 GAS PLANT

Absorber/Deethanizer Reboil Valve Function (#2)

easy-e ValveW8119

W2966 W3162 W0451

The reboil valve controls the amount of heat put intothe column by the reboiler. In many cases, steam isused as a heat source. Steam valves are usuallyvery reliable. The service is very clean, and fugitiveemissions are not a concern. However, a problemvalve will make the column difficult to controlprecisely. This will be especially true if the columnfeed is subject to frequent changes.

Not all reboilers use steam as a heat source. Tosave energy, many refineries have integrated theirunits so that higher-temperature process streamsare used to provide heat for lower temperatureprocesses. In these cases, the reboil valve will foulmore easily and might be a concern for fugitiveemissions.

Absorber/Deethanizer Reboil Valve Specification (#2)


Steam Dependent on process, typically 10.3 bar (150psig) saturated steam





vapor back up through the column. Vapor though thecolumn affects column efficiency.



GAS PLANT 35

Fractionator Overhead Valve Function (#3)


W8192

W7435

This is the feed valve to the absorber/deethanizer.However, it also is the fractionator overhead productvalve. The flow through this valve will normally beset to control the fractionator overhead receiverlevel. Therefore, any control problems with thefractionator overheads will ripple through the gasplant.

Feed valves are usually set up as flow or levelcontrol loops. An upstream unit or process oftencontrols the valve.

Unstable feed flow will make the distillation columndifficult to control. A problem valve will often causethe feed flow to oscillate. As a result, the column willalternate between too little and too much reboil heat.Depending on the size and number of trays in thecolumn the effect of a swing in the feed will takeanywhere from several minutes to more than anhour to reach the ends of the column. Sometimes,the reboil and reflux controls will amplify the swings.The final result is that meeting product purity targetsbecomes more difficult. Operations will normallyrespond by over-purifying the products, wastingenergy to compensate for the bad feed control valve.

Fractionator Overhead Valve Specification (#3)


Primarily reactor effluent Typically less than 34.5 bar (500 psig) Dependent on material being distilled


Lower flow rates (line size 4 inchesand smaller)

Heavy-duty, general-purposeglobe valves easy-e

valvesBalanced with graphite cage-plugseal

EDand smaller) globe valves easy e valves

Balanced with polymer cage-plugseal

ET

Higher flow rates (line size 6 High-capacity, high-rangeabilityVee Ball valves

Class 150 V150Higher flow rates (line size 6inches and larger)

High capacity, high rangeabilityV-notch rotary ball valves Vee-Ball


Process Impact

Control problems with this valve will produce aripple effect through the rest of the gas plant.


None

36 GAS PLANT

Sponge Absorber Overhead Valve Function (#4)


W8192W3162

This valve serves as the pressure controller for thegas plant. Because it is setting the pressure for theentire gas plant, it is important that this valveperform well. This is a minor stream in terms of flow(less than 1 MBPD) and has a value equal to that offuel gas.

It also is possible that the debutanizer or the C3/C4splitter will have a pressure control valve as well.

The pressure control valve is used to control thecolumn pressure. Higher column pressures will yieldbetter product purities, but require more energy tooperate. Normal operating procedure is to minimizethe pressure to lower energy costs while maintainingproduct specifications. There is a low limit becauselower pressures reduce the amount of vapor/liquidtraffic the column can handle and make it more likelyto flood.

The simplest way to control pressures is tocontinuously vent gas from the system. The sizing ofthe vent valve is critical. If the valve is too large, asmall valve movement will cause a large pressureswing. If the valve is too small, the pressureresponse will be very sluggish. It is likely that anundersized valve will operate from completely closedto completely open. In either scenario, an oscillatingcolumn pressure and difficult column control are theresult. A sticking pressure control valve will presentthe same problem. A sticking valve is a commonconcern on vent gas valves because the valvepacking will normally be tight to prevent fugitiveemissions.

Many distillation columns also use what is known asa hot vapor bypass valve to control pressure. Inthis case, some of the hot overhead vapors arebypassed around the overhead condenser heatexchanger. The amount of bypass will control thepressure. This eliminates the constant venting ofprocess gas, which usually goes to a low valuerefinery waste fuel gas system. Unfortunately, thepressure response on a hot vapor bypass valve isnormally very sluggish due to slow process responsetime. Like the vent gas valve, this valve is a concernfor fugitive emissions, and the packing is likely to betight. A sticking valve will cause wide, slowoscillations in column pressure. The product puritieswill likewise swing widely and slowly. The responseof refinery operations personnel will usually be toover-purify.

A majority of columns with a hot vapor bypass valvewill use it in combination with a vent gas valve. Inthese cases, a single pressure control loop willmanipulate both valves. At lower pressures, the hotvapor bypass valve is used. As the pressure rises,there will be a transition point where the hot vaporbypass valve closes fully and the vent gas valvestarts to open. At high pressures, the vent gas valvecontrols the pressure. This configuration often leadsto pressure control problems, as the hot vaporbypass and vent gas valves will have differentcontrol characteristics. Also, it is unlikely that onevalve will close precisely at the moment the othervalve opens. If the column constantly transitionsbetween using the hot vapor bypass and vent gasvalves, the pressure will normally oscillate. This is atuning rather than a valve problem, but it should bekept in mind for column design or valve resizing.

GAS PLANT 37

Sponge Absorber Overhead Valve Specification (#4)


Distillate light-end hydrocarbon liquid andnoncondensible gas

Dependent on process design Less than 93C (200F)






Process Impact

Controls the back pressure to the distillationcolumn

Special Considerations Packing on these valves is important to reduce

fugitive emissions.

Consider using special materials for the spongeabsorber overhead valve if there is an acid gasenvironment.

38 GAS PLANT

Absorber/Deethanizer Bottom Product Valve Function (#5)

Vee-Ball Valve

W8192W5791

eplug Valve

W5793



Absorber/Deethanizer Bottom Product Valve Specification (#5)


Light-end, lower boiling point hydrocarbon Dependent on process design Less than 343C (650F)

Valve Types




General- and severe-service eccentric rotary-eplug valves

High capacity, rugged CV500General and severe service eccentric rotaryplug valves eplug

valvesMore rugged construction V500

Process Impact

Dependent on downstream destination.

Special Considerations Ball valves or eccentric plug valves might

require Stellite (Alloy 6) or ceramic trim materials

Low-flow, clean fluids or small line sizeapplications could use globe valves

GAS PLANT 39

Absorber Lean Oil Valve Function (#6)

Vee-Ball Valve

W8192 W5791

eplug Valveeasy-e Valve

W8119

Some of the debutanizer bottoms is returned as leanoil to the absorber/deethanizer to absorb heaviercomponents out of the deethanizer overheadstream. If the lean oil valve has problems, such as

sticking, then some of the C3 and heavier materialmight be lost to the lower value fuel gas system.However, the performance of the deethanizer shouldstill be stable.

Absorber Lean Oil Valve Specification (#6)


Light-end, lower boiling point hydrocarbon Dependent on process design Less than 343C (650F)

Valve Types









Process Impact



require Stellite (Alloy 6) or ceramic trim materials.

Low-flow, clean fluids or small line-sizeapplications could use globe valves

310 GAS PLANT

Debutanizer Bottom Product Valve Function (#7)

Vee-Ball Valve

W8192 W5791

eplug Valveeasy-e Valve

W3162



Debutanizer Bottom Product Valve Specification (#7)


Heavier, higher boiling boiling pointhydrocarbon (typically naphtha)


Valve Types









Process Impact

Dependent on downstream destination.




GAS PLANT 311

Debutanizer Reflux Valve Function (#8)

Design EW Valve Vee-Ball Valve

W2777

W8192

edisc Valve

W6234

The reflux valve is typically either a flow or columntemperature-control loop. It is used to adjust thepurity of the overhead product. The higher the refluxrate, the purer the overhead product will become.However, raising the reflux rate also will require

more reboil heat and eventually will flood the tower .

A poorly operating reflux valve will have the sameeffects as a bad feed valve. Product purities willoscillate, and the column will be difficult to control.

Debutanizer Reflux Valve Specification (#8)


Column light-end gases and liquids Dependent on distillation process Less than 93C (200F)

Valve Types

High-capacity, high-rangeabilityVee Ball valves

Class 150 V150High capacity, high rangeabilityV-notch rotary ball valves Vee-Ball






Heavy-duty, general-purpose globeeasy e valves

Balanced with graphite cage-plug seal EDHeavy duty, general purpose globevalves easy-e

valvesLarger sizes; expanded ends; balanced or unbalanced EW




Typically none

312 GAS PLANT

Debutanizer Reboil Valve Function (#9)

easy-e ValveW8119

W2966 W3162 W0451

The reboil valve controls the amount of heat put intothe column by the reboiler. In many cases, steam isused as a heat source. Steam valves are usuallyvery reliable. The service is very clean, and fugitiveemissions are not a concern. However, a problemvalve will make the column difficult to controlprecisely. This will be especially true if the columnfeed is subject to frequent changes.

Not all reboilers use steam as a heat source. Tosave energy, many refineries have integrated theirunits so that higher-temperature process streamsare used to provide heat for lower temperatureprocesses. In these cases, the reboil valve will foulmore easily and might have fugitive emissionconcerns.

Debutanizer Reboil Valve Specification (#9)







vapor back up through the column. Vapor throughthe column affects column efficiency.



GAS PLANT 313

Debutanizer Overhead Product Valve Function (#10)


W8192

W7435



Debutanizer Overhead Product Valve Specification (#10)

Media Pressure Range Temperature Range

Distilled light-end liquids Dependent on process design Less than 93C (200F)









None

314 GAS PLANT

C3/C4 Splitter Bottom Product Valve Function (#11)

Vee-Ball Valve

W8192 W5791

eplug Valveeasy-e ValveW8119



C3/C4 Splitter Bottom Product Valve Specification (#11)


Heavier, higher boiling boiling pointhydrocarbon


Valve Types





High capacity, rugged construction CV500General and severe service eccentric rotaryplug valves eplug




Process Impact





GAS PLANT 315

C3/C4 Splitter Reflux Valve Function ( #12)

POSI-SEAL Valve Vee-Ball Valve

W5811 W8192

edisc Valve

W8299

The reflux valve is typically either a flow or columntemperature control loop. It is used to adjust thepurity of the overhead product. The higher the refluxrate, the purer the overhead product will become.However, raising the reflux rate also will requiremore reboil heat and eventually will flood the tower.

A poorly operating reflux valve will have the sameeffects as a bad feed valve. Product purities willoscillate and the column will be difficult to control.

C3/C4 Splitter Reflux Valve Specification (#12)


Column light-end gases and liquids Dependent on distillation process Less than 93C (200F)

Valve Types

High-capacity, high-rangeabilityVee Ball valves

Class 150 V150High capacity, high rangeabilityV-notch rotary ball valves Vee-Ball






Heavy-duty, general-purpose globeeasy e valves

Balanced with graphite cage-plug seal EDHeavy duty, general purpose globevalves easy-e

valvesLarger sizes; expanded ends; balanced or unbalanced EW




Typically none

316 GAS PLANT

C3/C4 Splitter Overhead Product Valve Function (#13)


W8192W3162



C3/C4 Splitter Overhead Product Valve Specification (#13)


Distilled light-end liquids Dependent on process design Less than 93C (200F)









None

GAS PLANT 317

C3/C4 Splitter Reboil Valve Function (#14)

easy-e ValveW8119

W2966 W3162 W0451

The reboil valve controls the amount of heat put intothe column by the reboiler. In many cases, steam isused as a heat source. The service is very clean,and fugitive emissions are not a concern. Steamvalves are usually very reliable. However, a problemvalve will make the column difficult to controlprecisely. This will be especially true if the columnfeed is subject to frequent changes.

Not all reboilers use steam as a heat source. Tosave energy, many refineries have integrated theirunits so that higher temperature process streamsare used to provide heat for lower temperatureprocesses. In these cases, the reboil valve will foulmore easily and might have fugitive emissionsconcerns.

C3/C4 Splitter Reboil Valve Specification (#14)







vapor back up through the column. Vapor throughthe column affects column efficiency.



318 GAS PLANT

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Chapter 4

Crude Distillation

Other NamesCrude unit, crude fractionator, crude column, pipestill

DescriptionThe crude distillation unit is the first processing unitin a refinery. The unit is a complex distillation columnthat is used to separate crude oil into the basicproduct streams. The basic product streams from acrude distillation unit can vary widely depending onthe refinery operating objectives. Typical basicproduct streams are naphtha, kerosene, diesel, gasoil, heavy gas oil and bottoms. Normally, theseproduct streams are sent to downstream units forfurther processing before being sent to producttanks.

The crude oil is sent through a process heater and ispartially vaporized before entering the fractionatornear the bottom of the column. Refer to the chapter

covering the furnace (process heater). Strippingsteam also is injected at the bottom of the column.One or more process pump-around heat exchangerloops and a top reflux stream are used to cool therising vapors, separating the crude mixture into theproduct streams. The product streams are extractedthrough side draws to steam stripping columns. Thecolumn pressure and product draw temperatures areused to control the product streams to qualityspecifications, usually a final or 95% boiling point ofthe product steam.

42 CRUDE DISTILLATION

Typical Crude Distillation Column

CRUDE DISTILLATION 43

Control Valves

Feed Valve Function (#1)


W8192W3162

The feed to a crude distillation unit is crude oil fromthe oil fields. Feed valves are usually set up asflow-control loops. They are configured to fail openso that a valve failure will protect the furnace radiantsection tubes. If a radiant tube loses or hasinsufficient flow, the tube can quickly become so hotthat the metal can melt. This can have disastrousconsequences, as most process feeds makeexcellent fuels. A furnace can be destroyed veryquickly if a ruptured tube is dumping into the fireboxof the furnace.

Problem valves can lead to difficulties withcontrolling the outlet temperature of the furnaces.Also, many process feeds slowly build layers of coke

on the inside of the radiant tubes. Coking is anon-linear reaction, and in some processes even afew extra degrees of temperature can lead toexcessive coke build-up. If a flow valve is alternatelyprovided too much and then too little flow, thetemperature will also swing and will usually lead toexcessive coke buildup. This will shorten the furnacecycle time between decoking procedures, which willnormally require the process unit downstream toshutdown.

Feed valves can easily be bypassed whennecessary. A combination of the measured flow andany available pass temperatures can be used toregulate the bypass valve.

Feed Valve Specification (#1)


Primarily reactor effluent Dependent on process design Dependent on material being distilled

Valve Types

Lower flow rates (line sizes Heavy duty general purpose globeUnbalanced, cageless EZ

Lower flow rates (line sizes4 inches and smaller)

Heavy-duty, general-purpose globevalves easy-e

valves Balanced with graphite cage-plug seal ED4 inches and smaller) valves easy e valvesBalanced with polymer cage-plug seal ET

Higher flow rates (line sizes High-capacity, high-rangeability V-notchVee Ball valves

Class 150 V150Higher flow rates (line sizes6 inches and larger)

High capacity, high rangeability V notchrotary ball valves Vee-Ball


Process Impact

Minimal impact to process


Flashing might be present depending on theprocess variables


Pump-Around Valve Function (#2, #3)


W8192

W7435

A crude fractionator will always have at least onepump-around heat exchanger loop for controlling theheat balance. Most fractionators will have more thanone pump-around loop. The pump-around loop isused to extract heat from the column, creating theseparation between the product draws immediatelyabove and below the pump-around loop. Thepump-around valves are usually flow controllers.

A poorly performing or bypassed pump-around valvewill increase the variability in the qualityspecifications of the product draws. A valve failuremost likely will create an upset lasting from 30minutes to a few hours depending on the severity ofthe failure.

Pump-Around Valve Specification (#2, #3)


Hydrocarbon liquid Dependent on distillation column pressure Dependent on where steam is taken from thecolumn: 93 to 316C (200 to 600F)






Process Impact

Critical to maintaining heat balance around thecolumn

Special Considerations Typically none: dependent on distillation unit

and process

NACE materials


Fuel Valve Function (#4)


W8192W3162

Depending on the furnace service and configuration,this valve will normally be part of a loop that controlseither the fuel flow or pressure. These valves arespecified as fail closed so that a control loop failurewill not allow an excessive amount of fuel to bedumped into a hot furnace. A fuel valve failure willalmost always shut down the processing unitdownstream. Although many fuel valves havebypass circuits, Refinery operations personnel areusually reluctant to run a furnace on bypass for anylength of time because of safety concerns.

The preferred control loop configuration for the outlettemperature is a cascade to the set point of the loopcontrolling the fuel valve. Many furnaces will be setup such that the temperature control loop directly

manipulates the fuel valve. This direct connectionusually provides inferior control performance to acascade configuration. It is extremely susceptible toany valve dead band, such as that caused by asticking valve. This can be detected by excessiveoscillation in the outlet temperature.

When the fuel valve is manipulated by thetemperature loop or by a flow control loop, thereoften will be a pressure control valve upstream of thefuel valve. This valve also will fail closed and willhave the same consequences as a failure of the fuelvalve. However, with this configuration, operationspersonnel will be more willing to run a fuel valve inbypass as they still have a way to shut off the fuelquickly in an emergency.

Fuel Valve Specification (#4)


Natural gas-fuel gas mixtureFuel oil with atomizing steam




High-capacity, high-rangeability V-notchVee Ball valves

Class 150 V150High capacity, high rangeability V notchrotary ball valves Vee-Ball


Process Impact Performance is critical to controlling furnace

temperature

Performance is critical to reducing energy costsassociated with the furnace


Potential for acidic fouling gases (for example,H2S, HCL)


Bottoms Valve Function (#5)

Vee-Ball Valve

W8192W5791

eplug Valve

W5793

The bottom material becomes the vacuum distillationunit charge.

The bottoms flow does not usually have any impacton the operation of the crude fractionator unless a

failure causes the liquid level of the bottoms tooverfill or empty. Usually, level alarms on the unitallow the operator to catch this before it causes anupset.

Bottoms Valve Specification (#5)



Valve Types




General- and severe-service eccentriceplug valves

High capacity, rugged construction CV500General and severe service eccentricrotary-plug valves eplug


Process Impact



Could encounter higher viscosity materials,sludge and process media with entrained particles

Ball valves or eccentric plug valves mightrequire Stellite (Alloy 6) or ceramic trim materials.

Low-flow, clean fluids or small line-sizeapplications could use globe valves.


Reflux Valve Function (#6)

Design EW Valve Vee-Ball Valve

W2777

W8192

edisc Valve

W6234

The reflux valve is used to control the separationbetween the top product (usually naphtha) and thehighest-side draw product. The reflux valve can beeither a flow or a temperature controller.

A poorly performing or bypassed reflux valve willincrease the variability in the quality specifications ofthe overhead product and the top side draw. A valvefailure will most likely create an upset lasting from 30minutes to a few hours, depending on the severity ofthe failure.

Reflux Valve Specification (#6)



Valve Types









Balanced with graphite cage-plug seal EDHeavy-duty, general-purpose globe valves easy-e valves Balanced with polymer cage-plug seal ETy y g g y

Larger sizes; expanded ends; balanced orunbalanced

EW

Process Impact

Critical to maintaining vapor/liquid balance inthe column, ultimately affecting the efficiency of thecolumn


Typically none


Fractionator Stripping Steam Valve Function (#7)

easy-e ValveW8119

W2966 W3162 W0451

Stripping steam is injected into the bottoms of thefractionator to strip out lighter components from thecrude bottoms stream. The amount of strippingsteam also affects the separation efficiency of the

crude fractionator. A valve failure most likely willcreate an upset lasting from 30 minutes to a fewhours depending on the severity of the failure.

Fractionator Stripping Steam Valve Specification (#7)


Steam Dependent on process design, typically 10.3bar (150 psig) saturated steam

Dependent on material being distilled




vapor back up through the column. Vapor throughthe column affects column efficiency. Reboiler steamwill have a direct effect on overhead reflux flow.




Stripping Steam Valve Function (#8, #10)

easy-e ValveW8119

W2966 W3162 W0451

Each side-draw product stream usually feeds aproduct stripper. The stripper uses steam to drive offany light components remaining in the product

stream. Poor steam valve performance can lead tovariability in the quality specifications for the productstream.

Stripping Steam Valve Specification (#8, #10)


Steam Dep

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