The world-wide consumption of petroleum has seen a steady rise over the past twenty years; yet in the same time relatively few new refineries have been built, often due to the bureaucracy and red tape that has grown up around the industry in many countries.
One example of this is found in the United States, where legislation regarding the building of new refineries has become so strict that the last new refinery was built in 1976.
Yet even with relatively little new capacity being added to the worldwide total, the energy industry has been able to keep up with rising demand for petrochemical products. This increased capacity has been accomplished by focusing on expansions and upgrades of existing facilities.
With such a focus on facility expansion, the techniques and technology used to expand the capacity of refineries have evolved over the years as refinery operators seek to limit down-time during upgrades.
One tool which is being utilised more and more is the rental of chilling equipment during times of potential refinery down-time or slow-downs. Petrobras, Brazil’s largest energy company, has in recent years utilised rental chilling packages at several of its refineries in order to ensure that the refineries are able to meet their production targets.
Reducing the effects of summer heat
In a country such as Brazil, where summer temperatures can rise to 40 degrees Celsius, simply keeping a refinery at a consistent temperature can be a challenge.
At Petrobras’ Refinaria Presidente Bernardes de Cubatao (RPBC) refinery, high summer temperatures were decreasing air density in the air blower, thereby reducing air mass flow to the Fluid Catalytic Cracking Unit (FCCU).
In effect, the summer heat was causing refinery production losses of approximately 8%. With RPBC responsible for 11%of Brazil’s crude oil byproduct production, such a large production loss would have had an impact on the availability of petroleum products in the market.
Petrobras approached Aggreko, the specialist temperature control rental company, to supply them with a rental to increase refinery production during the summer.
Petrobras chose to utilise a rental solution as opposed to purchasing a permanent chiller for several reasons.
First of all, the cyclical nature of the power requirement meant that a purchased solution would have been unutilised for the majority of the year; by renting chillers only when they were needed, Petrobras was able to avoid the capital expenditure required for purchase.
Secondly, by contracting Aggreko to provide a turn-key chilling solution, Petrobras did not need to allocate staff for installation, operation or maintenance of the chillers – all aspects of plant servicing were Aggreko’s responsibility.
As well, all ancillary equipment, including fuel tanks and cables, were included in the package, allowing Petrobras staff to focus on their core activities.
The chilling solution included a series of chillers which produced 200 000 m3/h of cold air, which reduced the temperature of the FCCU by 12 degrees Celsius. With the seasonal chilling package in place, RPBC’s FCCU was able to operate at peak capacity during the summer months, ensuring that the company was able to meet its production targets.
Jose Adar Etter, Petrobras optimisation specialist, commented on the chilling system, saying: “The Aggreko chilling system has operated perfectly. The air from the chillers is released at a drier level than expected and consequently has a better oxygen rate. This has improved the regenerator reaction by providing better burning conditions.”
Chilling during refinery maintenance
At one of Brazil’s largest refineries, the Refinaria Duque de Caxias (REDUC), which has a capacity of 242 000 barrels per day, Petrobras was faced with the possibility of a partial plant stoppage due to regular maintenance.
The main cooling tower at the refinery required an overhaul of its systems, which meant that three of the refinery’s air compressors would not be able to operate.
The standard solution would have been to rent diesel air compressors for the duration of the upgrade, however, the higher level of emissions that would be caused by a diesel air compressor were a serious concern for Petrobras, who follow strict environmental procedures regulating emissions.
Petrobras technicians analysed the problem and determined that the emissions and cost of the upgrade would be substantially lowered by renting a cooling solution which would cool the permanent air compressors rather than shutting them down and installing temporary compressors.
Aggreko was contracted to supply a turn-key 1 400 tonne cooling package to REDUC. The package, installed in less than a week, allowed Petrobras to substantially reduce plant down-time, limit additional emissions and reduce the costs of the upgrade.
Emergency chilling
Although all refineries seek to limit downtime by scheduling regular maintenance programs which are often planned years in advance, it is unavoidable that from time to time unforeseen conditions will cause refinery operators to briefly shut down their equipment for emergency maintenance.
In situations like these, where down-time is unexpected and the length of time for repairs is unknown, rental chilling solutions can provide an important tool for operators seeking to restart operations as quickly as possible.
The Refinaria do Planalto (REPLAN), faced a situation wherein a faulty heat exchanger began leaking hydrocarbons into the refinery’s cooling water. If Petrobras was to keep its equipment off-line until the heat exchanger was fixed, it would result in at least 15 days of reduced production.
However, the technical team at Petrobras had already held consultations with Aggreko and had incorporated the company into their emergency planning. This meant that when the problem was discovered, Aggreko’s technicians had already been to the refinery and were familiar with its design and equipment.
Therefore, Aggreko was able to mobilise, install and commission a complete 700 tonne cooling solution to REPLAN within just three days, allowing REPLAN to continue operations as normal during the repair of the heat exchanger. The rental cooling solution resulted in a cost-savings equivalent to 12 days of production.
Rental chilling
As the world demand for petroleum and plastics products continues to grow, many of the refineries and petrochemical production plants currently in operation will need to be expanded and enlarged in order to increase their production capacity to keep up with rising demand, particularly in the Middle East.
By utilising rental cooling solutions for planned maintenance, facility upgrades and emergency down-time, companies such as Petrobras have been able to limit refinery down-time, resulting in substantial cost-savings for them, and ultimately, for their customers.
