ABSTRACT
The optimum equipment replacement time for the power plant at the new Port Harcourt Refinery is presented. In this presentation, maintenance of the entire plant was treated wholistically and an availability model for the entire plant developed. Applying the developed model, an availability of 25% after a period of twenty years was obtained for the plant. Various units that make up the plant were then identified, and their various failure densities statistically determined and analysed. The analysis revealed that majority of the refinery downtime results from the turbo-generators. For this reason, subsequent analysis was based on the turbo generating unit. Using Sharma’s model, a replacement period of 15years was found suitable for the turbo generators.
TABLE OF CONTENTS
Title page i
Certification ii
Dedication iii
Acknowledgement iv
Abstract v
Table of contents vi
List of Tables viii
List of Figures ix
CHAPTER ONE: INTRODUCTION 1
CHAPTER TWO: LITERATURE REVIEW
CHAPTER THREE:
CHAPTER FOUR:
CHAPTER FIVE: RESULT AND DISCUSSION
CHAPTER SIX: RECOMMENDATION AND CONCLUSION
- Conclusion
- Recommendation
REFERENCES
APPENDIX A
CHAPTER ONE
INTRODUCTION
1.1 Preamble
After project execution and commissioning, maintenance becomes one of the critical functions that keep a product plant going. The recognition, adoption and use of appropriate maintenance techniques significantly improve companies’ productivity and efficiency and enhance profitability through optimum plant availability and utilization.
The oil industry is one of the most maintenance sensitive and intensive industries world-wide (Onyemaechi, 2003). It ranks second only to the nuclear industry because of safety implications and costs involved. For large industry of this nature to succeed, the maintenance practices and culture must be tailored to meet the industry’s maintenance demands.
The Nigerian Petroleum Act of 1973 stipulates that oil refineries are expected to shutdown facilities after a maximum of thirty (30) months of operation to allow for major cleaning and repair work for technical and safety reasons (NNPC, 2003). However, Nigerian National Petroleum Corporation (NNPC), the manager of Nigerian refineries, adopted turn-around maintenance (TAM) frequency of twenty four months as a statutory requirement based on its wealth of experience.
Unfortunately, TAM practices have increasingly experienced schedule over-runs leading to rising post-TAM equipment failures and decreased run time between shut downs. This has resulted in shortage of petroleum products across the country. This makes life very difficult for an average Nigerian and affects the economy negatively. Hence, the need to analyze the maintenance procedures so as to have a background for a sustainable maintenance method is inevitable. This research work attempts to present an effective maintenance (TAM) criteria that will reduce the incessant breakdowns encountered in crude oil refinery through a careful analysis of the maintenance procedures.
1.2 Statement of the Problem
Nigeria is the 6th largest producer of crude oil in the world. Currently Nigeria produces about 3 million barrels of crude oil daily and has a reserve of about 36.2 billion barrels. Petroleum (crude oil) is the mainstay of Nigerian economy and accounts for about 90% of total export earnings and over 85% of Federal Government Revenue.
Since the building of the first refinery in 1965 till date, Nigeria has invested substantially in refineries, storage depots, pump stations, jetties and pipelines. With four refineries, both old and new at Port Harcourt, Warri and Kaduna, with a combined refining capacity of 445,000 barrels per day, Nigeria still lacks fuel for domestic consumption. Daily consumption of petrol (premium motor spirit) in Nigeria alone stands at about 30 million litres but the four refineries can only produce a combined output of about 13 million litres a day. There is also high consumptions of diesel (automotive gas oil) and kerosene. This shortfall which the Federal Government has unsuccessfully tried to augment by importation has brought a lot of hardship on Nigerians.
Preliminary studies have shown that one of the major factors responsible for this shortfall or low outputs of the refineries are operational problems among which maintenance problems are dominant. The nationwide scarcity of petroleum products is attributed to low availability of NNPC refinery plants. Even the adoption of turn-around maintenance cycle by NNPC has not eased off the situation. The new Port Harcourt Refinery Company has an installed capacity of 150,000 barrels per day but it hardly achieves 50% of its installed capacity, hence the need to have a critical analysis of the maintenance procedures in the new Port Harcourt refinery.
1.3 Objectives of the study
The major thrust of this research work is to critically examine the existing maintenance procedures/culture in the new Port Harcourt refinery as a basis for proffering solutions to the problems of low refinery products output. The work will ultimately lead to the presentation of a mathematical model for use in determination of the availability of the plant machines. Effort would be made to use the result of the availability analysis and other existing models in the literature to prescribe a replacement period for the critical equipment.
1.4 Background of the work
Unless action is taken to renew (maintain) industrial equipment, most of them deteriorate with age and usage. Consequently, the question of when a machine should be replaced becomes very important in planning for maintenance in any industry where production is continuous. Maintenance can be carried out on all machines simultaneously or on a single machine. The advantage of performing maintenance on a single machine is obvious. It ensures that machine is indeed mature for maintenance and eliminates the cost of maintaining some machines prematurely in an attempt to carry out maintenance on all machines simultaneously, Ozor (2008). This work will consider mainly the availability of maintained equipment in the new Port Harcourt refinery with a view to proffering a replacement policy for the critical unit or component.
1.5 Significance of the work
The major significance of this work is that it will introduce a new model in availability analysis. Its application will also be tested at the new porth Harcourt refinery. So, the work, it is hoped, will successfully lead to the presentation of the optimum maintenance and replacement time for the new Porth Harcourt refinery.Even though the proposed design will only apply to the new Porth Harcourt refinery, it can easily be tailored to suit other spheres with similar parameters.
1.6 Scope of the work
This research is concerned with only the development and application of an optimum availability model to the new Port Harcourt refinery, and the prescription of a replacement period for a critical component in the plant. It will not consider the numerous other possible applications of the models that will be developed in other industries, which might bring about new specifications of the parameters. In fact, the work, though generalized, will make use of operational and interview data sourced from the new Port Harcourt refinery. Eleme, Rivers State, Nigeria to obtain the maintenance policy prescribed.
1.7 Methodology of the work
The methodology for the development of the plant availability model follows an approach similar to that suggested for most maintained systems due to Lie et al (1979). Various categories of availability models of maintainable systems are reviewed from some Maintenance Engineering works, see for example, Ebeling (1997), Leitch (1988). Thereafter, a generalized availability model is developed to capture some critical parameters in the refinery without which, the final result would have lacked credence. Failure and cost data sourced from the refinery, and reflecting normal use of the equipment are analyzed statistically. A critical component contributing the greatest causes of plant downtime is then identified and a replacement period sought for the component using Sharma’s model.
1.8 Maintenance
Maintenance planning is a subject of concern to many industrial sectors as plant safety and business depend on it, (Martorell et al, 2010). The fundamental purpose of maintenance in any business is to provide the required capacity for production at the lowest cost. Production is the reason for an organization existing. It is evident for process or batch production plants, but other organizations such as buildings, hospitals, the military, transport, and of course refineries need their own measure of output or of ongoing success. Maintenance work often includes major machine replacements or upgrades, which are often capital works projects, [Beebe, 2004].
Maintenance of equipment and machinery in any industry is a problem demanding enormous resources of manpower and materials. For a plant, machinery and equipment to remain in acceptable condition and ready for use when they are required, it is very essential that maintenance tasks should be carried out on them. The decision is never whether maintenance should take place, but the form it should take to make it economically effective, (Koboa-Aduama, 1991). Hence, maintenance in recent times, like any other economic activity, is subject to management policy, consideration and decision. For manufacturing firms, maintenance costs can reach 15-70% of total production costs as most of maintenance operations have a corrective function and are executed mainly in emergency conditions, Ponchet et al (2010). For this reason, since the 1950s, maintenance models have been widely studied in order to improve maintenance activities and reduce maintenance cost. Since time inexorably marches on, modern and sophisticated machines are installed in crude oil refineries. This certainly calls for modifications in the maintenance techniques and necessitates more and better data for any crude oil refinery to manage its business effectively. Thus, the existing ways and maintenance procedures must be investigated in order to discover possible improvements and to discover the factors that may lead to greater efficient maintenance practice.
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