LECTURE 06 Equipment Sizing and Capital Cost Estimation

Guidelines for the design and operation of petrol vapour emission controls at distribution terminals

4th edition

GUIDELINES FOR THE DESIGN AND OPERATION OF PETROL VAPOUR EMISSION CONTROLS AT DISTRIBUTION TERMINALS

4th edition

Oct 2014

Published by ENERGY INSTITUTE, LONDON The Energy Institute is a professional membership body incorporated by Royal Charter 2003 Registered charity number 1097899

The Energy Institute (EI) is the chartered professional membership body for the energy industry, supporting over 19 000 individuals working in or studying energy and 250 energy companies worldwide. The EI provides learning and networking opportunities to support professional development, as well as professional recognition and technical and scientific knowledge resources on energy in all its forms and applications. The EI’s purpose is to develop and disseminate knowledge, skills and good practice towards a safe, secure and sustainable energy system. In fulfilling this mission, the EI addresses the depth and breadth of the energy sector, from fuels and fuels distribution to health and safety, sustainability and the environment. It also informs policy by providing a platform for debate and scientifically-sound information on energy issues. The EI is licensed by: − the Engineering Council to award Chartered, Incorporated and Engineering Technician status; − the Science Council to award Chartered Scientist status, and − the Society for the Environment to award Chartered Environmentalist status. It also offers its own Chartered Energy Engineer, Chartered Petroleum Engineer and Chartered Energy Manager titles. A registered charity, the EI serves society with independence, professionalism and a wealth of expertise in all energy matters. This publication has been produced as a result of work carried out within the Technical Team of the EI, funded by the EI’s Technical Partners. The EI’s Technical Work Programme provides industry with cost-effective, value-adding knowledge on key current and future issues affecting those operating in the energy sector, both in the UK and internationally. For further information, please visit http://www.energyinst.org The EI gratefully acknowledges the financial contributions towards the scientific and technical programme from the following companies BG Group BP Exploration Operating Co Ltd BP Oil UK Ltd Centrica Chevron ConocoPhillips Ltd Dana Petroleum DONG Energy EDF Energy ENI E. ON UK ExxonMobil International Ltd International Power Kuwait Petroleum International Ltd Maersk Oil North Sea UK Limited Murco Petroleum Ltd Nexen Phillips 66

Premier Oil RWE npower Saudi Aramco Scottish Power SGS Shell UK Oil Products Limited Shell U.K. Exploration and Production Ltd SSE Statkraft Statoil Talisman Sinopec Energy UK Ltd Total E&P UK Limited Total UK Limited Tullow Valero Vattenfall Vitol World Fuel Services

However, it should be noted that the above organisations have not all been directly involved in the development of this publication, nor do they necessarily endorse its content. Copyright © 2014 by the Energy Institute, London. The Energy Institute is a professional membership body incorporated by Royal Charter 2003. Registered charity number 1097899, England All rights reserved No part of this book may be reproduced by any means, or transmitted or translated into a machine language without t he written permission of the publisher. ISBN 978 0 85293 718 1 Published by the Energy Institute The information contained in this publication is provided for general information purposes only. Whilst the Energy Institute and the contributors have applied reasonable care in developing this publication, no representations or warranties, express or implied, are made by the Energy Institute or any of the contributors concerning the applicability, suitability, accuracy or completeness of the information contained herein and the Energy Institute and the contributors accept no responsibility whatsoever for the use of this information. Neither the Energy Institute nor any of the contributors shall be liable in any way for any liability, loss, cost or damage incurred as a result of the receipt or use of the information contained herein. Hard copy and electronic access to EI and IP publications is available via our website, www.energypublishing.org. Documents can be purchased online as downloadable pdfs or on an annual subscription for single users and companies. For more information, contact the EI Publications Team. e: [email protected]


CONTENTS Page Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Guide to contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1

Introduction and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.1 Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.2 Scope .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .8 1.3 Control technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.1 Above-ground storage tanks at terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.2 Loading of mobile containers (road tankers, rail tank cars and marine vessels). . . . 8

2

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2 Floating roof tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.1 External floating roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.2 Internal floating roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.3 Seal systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.3 Vertical fixed roof tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.3.1 Connection to a VRU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.4 Horizontal cylindrical tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3

Road tanker vapour system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.3 System design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.4 Control of vapour system integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.5 Principal components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.5.1 Pressure-vacuum breather valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.5.2 Emergency pressure relief valve (EPRV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.5.3 Vapour transfer valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.5.4 Connecting hose to vapour manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.5.5 Vapour manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.5.6 Vapour manifold valve (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.5.7 Vapour down pipe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.5.8 Vapour adaptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.5.9 Interlock for hose coupler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.5.10 Pressure switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.5.11 Overfill prevention system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.6 Possible malfunctions when loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4

Rail tank car loading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.3 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.3.1 Rail tank car depressurisation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.3.2 Top loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.3.3 Bottom loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1


4.4 4.5 4.6

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

5

Marine loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.3 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.4 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.5 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.6 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6

Vapour collection systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.3 Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.3.1 General considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.3.2 Vapour collection system types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.3.3 Connections to the vapour collection system . . . . . . . . . . . . . . . . . . . . . . . . 30 6.3.4 Vapour piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 6.3.5 Vapour holder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 6.3.6 Storage tank vapour balanced systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 6.3.7 Vapour collection system sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 6.4 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 6.4.1 Hazard and operability study (HazOp) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 6.4.2 System over/under pressure protection and emergency venting . . . . . . . . . . 38 6.4.3 Fire and explosion protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 6.5 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 6.6 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

7

Vapour recovery units (VRUs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2 VRU types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2.2 Carbon adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2.3 Membrane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.3 Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.3.1 Design parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.3.2 Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 7.3.3 Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 7.3.4 Other consumables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.3.5 Control of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.4 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4.1 Hazard and operability (HazOp) study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4.2 Hazardous area classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4.3 Discharge of vapour during VRU shutdown . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4.4 Ventilation of enclosed spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4.5 Fire-fighting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.5 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 7.5.1 Operational procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 7.5.2 Prevention of high temperature excursions in carbon adsorption type VRUs . . 50 7.5.3 Recovery measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 7.5.4 Performance and vent emission monitoring . . . . . . . . . . . . . . . . . . . . . . . . . 54

2


8

VRU inspection and maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 8.2 Mechanical integrity inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 8.3 Maintenance plan considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 8.4 Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 8.4.1 Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 8.4.2 Specialised equipment and skills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 8.4.3 Instrumentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 8.5 Testing of alarms, shutdowns and emergency shutdowns . . . . . . . . . . . . . . . . . . . . 57 8.6 Daily maintenance and operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 8.6.1 Example of preventative maintenance checks and procedures . . . . . . . . . . . 58 8.7 VRU testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 8.7.1 Compliance and emission testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 8.7.2 Duty reclaim testing at duty suspended facilities . . . . . . . . . . . . . . . . . . . . . 59 8.7.3 Capacity test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Annexes: Annex A Annex B Annex C Annex D Annex E Annex F Annex G Annex H Annex I

Requirements of the European Directive 94/63/EC on the control of VOC emissions during petrol storage and distribution . . . . . . . . . . . . . . . . . . . . . . . 61 Sizing of vapour collection and recovery systems. . . . . . . . . . . . . . . . . . . . . . . 63 Thermal oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Vapour balancing during rail tank car off-loading . . . . . . . . . . . . . . . . . . . . . . 74 Model sequence for dealing with a temperature excursion in a carbon adsorption type VRU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 VRU emission measurement test method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 A model baseline survey for the development of a mechanical integrity inspection programme for carbon adsorption type vapour recovery units . . 93 Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

3


FOREWORD This publication has been prepared by the Vapour Recovery Working Group of the EI’s Distribution and Marketing Committee. EU Directive 94/63/EC placed controls on volatile organic compound (VOC) emissions resulting from the storage of petrol and its distribution from terminals to filling stations. The first two editions of this publication provided information to assist terminal operators and filling station operators in their design and operation of vapour emission controls. The third edition, published in 2008, focused solely on the design, operation and maintenance of petrol vapour emission control systems at petrol distribution terminals, with comprehensive guidance on emission controls at filling stations being provided in the joint EI/APEA publication Design, construction, modification, maintenance and decommissioning of filling stations. This fourth edition provides an update on the 2008 publication taking account of industry experience of the operation and maintenance of vapour emission control systems over the last five years. As carbon adsorption type vapour recovery units are the norm in the UK, more detailed guidance on the operation of these types of units is included, in particular concerning the control of high temperature excursions. The revision of the guidelines has been undertaken to incorporate good practice learnt during the implementation of EU Directive 94/63/EC, both in the UK, and elsewhere in Europe. Although this publication has been written in response to European legislation, it is the intent that the recommendations are applicable wherever Stage 1 petrol vapour emission controls are to be implemented. The information contained in this code is provided as guidance only and while every reasonable care has been taken to ensure the accuracy of its contents, the EI cannot accept any responsibility for any action taken, or not taken, on the basis of this information. The Energy Institute shall not be liable to any person for any loss or damage which may arise from the use of any of its publications. Suggested revisions are invited and should be submitted to the Technical Department, Energy Institute, 61 New Cavendish Street, London, W1G 7AR.

4


ACKNOWLEDGEMENTS This fourth edition of the guidelines was prepared by the EI’s Vapour Recovery Working Group, comprising: Keith Bell Ian Goldsworthy Robert Harris Phil Lambeth Rex May Paul Miller Tom Ramsey Jeff Robson Ray Sewart Jonathan Silk Brian Smithers Andrew Sykes Toni Needham

ConocoPhillips Valero Amber Engineering Consultancy Ltd BP Oil UK BP Oil UK ConocoPhillips ExxonMobil SGS Roplex Ltd Total Vopak (on behalf of the Tank Storage Association) Consultant (Chair) EI EI

The EI wishes to record its appreciation of the work carried out by them, and thanks are also extended to Neil Bretherick (Emco Wheaton), John Robson (SGS Roplex Ltd) and Dave de Halle (Phillips66) for their assistance in the updating of these guidelines. Technical editing and project coordination was carried out by Brian Smithers (Consultant to EI) and Andrew Sykes and Toni Needham (EI).

5


GUIDE TO CONTENTS

SECTION 1

INTRODUCTION AND SCOPE

VAPOUR EMISSION CONTROLS DURING:

SECTION 2

STORAGE

SECTION 3

ROAD TANKER VAPOUR SYSTEM

SECTION 4

RAIL TANK CAR LOADING

SECTION 5

MARINE LOADING

SECTION 6

VAPOUR COLLECTION SYSTEMS IN TERMINALS

SECTIONS 7 AND 8

VAPOUR RECOVERY UNITS ( VRUs )

ANNEX C

THERMAL OXIDATION

ANNEX D

VAPOUR BALANCING DURING RAIL TANK CAR OFF-LOADING

6


1

INTRODUCTION AND SCOPE

1.1

BACKGROUND

Concerns about the environmental and health effects of emissions of non-methane volatile organic compounds (NMVOCs) have led to European legislation imposing emission controls on the principal man-made sources of NMVOCs, e.g. solvents and petrol-powered automobiles. In addition, Directive 94/63/EC mandates emission reductions during the distribution of petrol. The reduction in emissions during the storage, loading, and off-loading of petrol is known as ‘Stage 1’ vapour control. Stage 1 is subdivided into: − −

Stage 1a: the control of emissions during the receipt, storage and loading of petrol at terminals, and Stage 1b: the control of emissions during off-loading of road tankers into service station storage tanks.

European legislation has also been introduced to control emissions during the refuelling of automobiles. Directive 2009/126/EC mandates so-called ‘Stage 2’ controls which require modification of the petrol dispenser permitting the vapours displaced from the automobile fuel tank to be fed back to the filling station storage tanks. The abatement of refuelling emissions can also be undertaken, as is mandated in the USA, by using a larger version of the carbon canister system which is currently installed on-board the automobile to control fuel system evaporative losses. Figure 1 shows the location of the stages diagrammatically. Both Stages 1 and 2 are ‘closed’ systems in which vapours are prevented from being vented to atmosphere by being captured and collected for subsequent processing; for example, in a vapour recovery unit (VRU).

Refinery

Loading, transport and terminal operations

Delivery to service stations

Stage 1 Stage 1a

Stage 1b

Automobile refuelling

Stage 2 or onboard carbon canister

Figure 1 The ‘stages’ of vapour emission controls

7


1.2

SCOPE These guidelines focus only on the design, operation and maintenance of vapour emission control systems at petrol distribution terminals, i.e. Stage 1a. The principles outlined may also be used at other sites, e.g. refinery off-sites, bulk liquid storage terminals, etc, although these may have their own additional specific considerations to be taken into account that are not addressed here. These guidelines apply to vapour collection and control systems for petrol vapour. They may not be appropriate for the control of emissions from the storage or handling of other products. Although the guidelines have been influenced by the need t o comply with Directive 94/63/EC, it is the intent that they may be used wherever petrol vapour emission controls are to be installed. The guidelines have been written without reference to other legislation or local requirements which also have to be met in the installation and operation of control equipment. Only single stage vapour recovery technologies are addressed in the guidelines. No guidance is given on the installation and operation of more complex multi-stage units designed to meet emission limits which are much more stringent than those required by the Directive. For marine loading, the guidelines discuss primarily the on-shore vapour collection and control systems. For sea-going vessels the on-ship equipment requirements have been formulated by the International Maritime Organization (IMO) in MSC Circular 585 Standards for vapour emission control systems.

1.3

CONTROL TECHNOLOGIES

1.3.1

Above-ground storage tanks at terminals It is possible to reduce evaporation in storage tanks significantly by covering the surface of the petrol with an external or internal floating roof. This technique is already widely used within the oil industry. Alternatively, vapours formed by evaporation in a fixed roof tank can be captured by connecting the vent of the tank directly to a vapour control system.

1.3.2

Loading of mobile containers (road tankers, rail tank cars and marine vessels) Directive 94/63/EC mandates that petrol vapours displaced from mobile containers whilst being loaded should be returned through a vapour-tight collection system to a VRU. At terminals where petrol is loaded onto inland waterway barges under certain circumstances vapour thermal oxidation can be substituted for recovery (see Annex A). The vapours displaced during the loading of a mobile container can be captured and fed to a vapour control system by the following means: − Bottom loading: the vapours can be collected by connecting the vapour space(s) of a mobile container to a common vapour line. This can then be connected to a terminal vapour collection system. This is the loading mode mandated in the Directive for road tankers. − Top loading: the vapours can be captured by modifying the loading arm so that the vapours are displaced directly into the terminal vapour collection line. This loading mode is the most commonly used in Europe for rail tank cars.

8

LECTURE 06 Equipment Sizing and Capital Cost Estimation

Recommend Documents