Petroleum Refineries

A Troubleshooting Guide

Dhananjoy Ghosh

• Publisher: Jenny Stanford Publishing
• Year: 2021
• eBook ISBN: 9781000400885
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Industrial & Technical Chemistry
• Index: Technology & Engineering

In petroleum refineries, although there are sets of standard operating procedures to operate the plants, unique problems often arise, which need to be tackled with engineering knowledge and experience without much loss of energy and time. This process is termed 'troubleshooting', and it saves production loss, leading to profitability and sustainability of the refinery operation.

This book covers the ins and outs of troubleshooting in petroleum refineries, with an analysis of the problems faced, the fundamentals behind them and logical reasoning and illustrations to solve the problems, along with lessons learnt. This is the first such book on the market since the publication of one by Norman P. Lieberman about 30 years ago, and there has been a massive change in technology since then. This book will not only enlighten practicing engineers in refineries and postgraduate students but also facilitate the creation of a knowledge bank on troubleshooting case studies, helping share engineering knowledge and experiences.

Chapter 1 Introduction

Dhananjoy Ghosh

1.1 Definitions

Troubleshooting is a common affair the individuals or organizations exercise for their survival.

In petroleum refineries also, though there are sets of guidelines/SOPS to operate the plants, sometimes unique problems arise which need to be tackled with knowledge, experience and ready wittiness to overcome the problems without much loss of energy and time. Once it is achieved, it is termed as troubleshooting, and becomes documentable.

1.2 Objectives and Approach

In refineries, capacity utilization, energy intensity index, process efficiency, and on-stream factor/availability are the key parameters that contribute a lot to refinery profitability and sustainability. Like other benchmarking organizations, Solomon Associates, USA, has developed all benchmarks with respect to the performance of refineries. The author has been associated with the audit of Indian refineries in benchmarking studies.

Various operational upsets in refineries result in poor gradation in refinery ranking with respect to all the above-mentioned parameters.

Hence, troubleshooting during any operational problem, when it arises, refinery operating crew get engaged to resolve the issue at the earliest to save operational losses as mentioned above.

For example, if the standby cannot be started in time due to the failure of a pump or a compressor, this leads to the shutdown of the process units or reduction in capacity; similar problems may also occur in distillation columns, vessels, reactors, exchangers, piping and fittings, which also cause a shutdown of the process unit or reduction in capacity. Intermittent failure on these accounts or delay in resolving the issues ultimately causes downward gradation of the above-mentioned performance parameters thereby resulting in heavy losses to the refinery.

Hence, having a good knowledge and expertise in troubleshooting reduces these losses. Though basic theoretical knowledge on the subjects is necessary for troubleshooting, experience plays a great role in quick troubleshooting as discussed earlier also. To facilitate quick troubleshooting, key issues in troubleshooting are discussed in respective chapters of the book. With the right background and experience along with apt for troubleshooting, reflect develops among the operating professionals; these qualities among the operating crew and the team leads facilitate troubleshooting very quickly minimizing the operational loss.

However, it is not wise to reinvent the wheel, i.e., troubleshooting experiences should be well documented and be made traceable in need to avoid the repetition of hit and miss trials when the same problem arises.

For continuous engagement without break in petroleum refineries for more than three decades, it was possible to know the ins and outs of the processes in association with almost all refinery processes in various forms from ground-level engineer in the field up to monitoring engineer for technical services and subsequently in a leadership position responsible for the whole refinery process units and offsite.

In documenting all the experiences, an effort has been made to explain in detail the problems first, and then troubleshooting approaches and solutions achieved have been narrated in all the cases as much as needed. Troubleshooting descriptions are mainly of text nature with reasoning and illustrations (wherever required); formulae, correlations have been used in the section where key issues in troubleshooting have been discussed. Hence, in discussing case studies, it is assumed that readers will be able to link the analogies in troubleshooting with mathematical correlations wherever required. Lessons on the respective troubleshooting cases have also been focused mostly. In some cases, where there were multiple causes or there were multiple probable solutions for a particular problem, and also where cases studies in those areas were enormous and commonly experienced, general demonstrations on troubleshooting are given on those scenarios.

So massive categories of troubleshooting experiences have been shared through this book that it will be easy for the engineers not only to become conversant to tackle those types of problems, if they arise, but also to arrive at quick solutions for non-repeating problems thereby enhancing their analytical skills and refinery profitability.

Troubleshooting skills of the engineers engaged in operation depends not only on their pre-education in alma mater and their engagement in operation of units, but also on knowledge in other disciplines like mechanical, electrical and instrument engineering. Hence, to build up knowledge on other disciplines as mentioned above, troubleshooting experiences with respect to problems in the processes due to causes contributed by reasons in multidiscipline engineering have been focused equipment-wise. Troubleshooting of almost on all technologies operative in petroleum refineries has also been discussed in separate chapters as follows.

Chapter 2Traceability of Relevant Troubleshooting Experience

Traceability is one of the most discussed subjects in refineries which contribute a lot with respect to profitability and sustainability in refinery operation. Thrust is given on this aspect in ISO standards fulfilling criteria. All ISO accredited refineries, hence, give much importance to traceability of documents/knowledge.

While troubleshooting was concentrated on problems arising in a process unit’s operation and in offsite areas operation in refineries, it was observed that problems are encountered in a particular furnace, column, exchanger, pump, compressor, other equipment/fittings, or in the process technology, which resulted in upset of the whole operation of the unit and the refineries solve the problems in due course.

Hence, to ensure easy traceability of the relevant experiences, gained in addressing the plant problems in concern, an effort has been made to list out all experiences relating to major types of equipment as mentioned above and also with respect to minor types of equipment like pressure safety valve (PSVs), isolation valves, Induced Draft/Forced Draft (ID/FD) fans, etc. In some specific case studies, it was found to be difficult to draw a distinction with respect to the identification of the root causes of problem whether it was due to column or exchanger; in those cases, the case study has been repeated in both column and exchanger category and the repetition mentioned in the respective areas. Hence, readers may have to explore alternative categories of troubleshooting in the index for a particular case in extreme cases where it is found missing in an expected category.

Experiences in utilities and offsite areas have been documented under separate heading irrespective of categorizing against equipment.

There have been experiences in troubleshooting in process units where problems arose on poor performance with respect to technology in use/operation due to which product quality, yield, or unit capacity was getting limited. Troubleshooting experiences of this kind have been documented under a separate heading. All refinery process technologies have been covered in this category, including sulphur recovery unit (SRU) which is used for SO₂ emission control of refineries.

Like the traceability issues in documenting all troubleshooting experiences as discussed above, operating engineers also should ensure proper placement of the experiences in all respective process units and offsite either in distributed control system (DCS) screens and/or as hard copy documents in the respective work stations to ensure easy reach in need.

If possible, it is advisable to keep the book as a ready reckoner for individual engineers to refer with respect to traceability to colleagues in their relevant discussions.

Chapter 3Methodologies in Troubleshooting

The first and foremost point is operating personnel should always be able to compare actual operating data with design operating data and more preferably with a test run operating data (when achievement of design performance is checked).

Following are the pre-requisites for good troubleshooting:

1. Logbook should be well maintained in operation.
2. Piping and instrumentation diagram (P&IDs) and process flow diagram (PFDs) should be kept updated.
3. Maintenance and inspection (M&I) shutdown activities should be well recorded.
4. All equipment datasheets should be available.
5. Maintenance history of rotaries should be well recorded.
6. In addition to having knowledge on respective disciplines, engineers should be apt to gather knowledge in petroleum technologies also.
7. Generally, chemical engineers are engaged with a responsibility to control the process operations with services from multi-disciplinary engineers. But, in a refinery, chemical engineers should also have the aptitude to gain knowledge in mechanical, electrical, instrument and civil engineering to some extent to facilitate understanding and communicating to all concerned.
8. Concept on HAZOP study should be learnt.

Similarly, the following procedures should be applied to troubleshoot the problems quickly:

1. Understand properly the unwarranted deviation which has occurred in the system.
2. To find whether a problem in any equipment was due to the process or not and if yes, what change has occurred in the process. If not, whether the problem should be due to an inherent problem that occurred in the equipment or due to ignoring some minor problem for long.Note: while thinking on the process, colleagues should be discussed for exchange of views, and for analysing on the types of equipment, engineer colleagues in respective disciplines, viz., mechanical/electrical/instrumentation/civil engineers should be engaged in the thought process.
3. for problems in product quality, yield and/or unit capacity limitation to maintain product qualities and product slate not attributed to any equipment, analysis on the technology in operation should be done thoroughly. To do it effectively, one should be well prepared with knowledge gained through training on that technology. Licensor’s commitment to the process and/or catalyst(s) should be properly checked and should also check whether any deviation occurred or not in the process from licensor’s guidelines.
4. Sometimes problems occur out of issues in metallurgy not considered in the design or engineering adequately; hence, for any corrosion problem in doubt, metallurgists of the organization should be engaged in the discussions.
5. Many problems arise in refineries due to malfunctioning or limiting of instruments and problems in a process control loop. So, while analysing the instruments or any control loop, instrument engineers should be engaged in troubleshooting.
6. Sometimes it is confusing to understand whether the problem is in electrical equipment and/or its circuit or not; hence, electrical engineers also should be involved in the troubleshooting discussion.
7. Multidisciplinary engineers can be called in the second phase of discussion after completing a primary review among the operating crew.

Chapter 4Key Issues in Troubleshooting

4.1 Pump

Pump failure/malfunctioning are sometimes observed to be the root cause of the problem. A pump operation is upset with an abnormal flow rate of the liquid from the process which it can’t handle as per its datasheet like very low flow rate below pump turndown capacity or due to very high flow than pump maximum capacity; both the cases result in level build up in the column/vessel from which it was taking suction; sometimes, its net positive suction head (NPSH) availability problem occurs, which can also result in similar effect-when available NPSH comes down to a level below its specified requirement in the datasheet, it loses suction and causes vapour locki...

Table of contents

• Cover Page
• Half-Title Page
• Title Page
• Copyright Page
• Dedication
• Acknowledgment
• About the Author
• Preface
• 1. Introduction
• 2. Traceability of Relevant Troubleshooting Experience
• 3. Methodologies in Troubleshooting
• 4. Key Issues in Troubleshooting
• 5. Troubleshooting Case Studies in Equipment/Facility Operation
• 6. Troubleshooting Case Studies in Technologies Operation
• Index