Jan-2011

Rental strategies counter seasonal performance problems

Engineered solutions can reverse the adverse effects of high temperatures and humidity. Petrochemical and refinery processes rely on efficient heat transfer to maximise efficiencies and ensure safe operations.

Umesh Mathur
Aggreko Process Services

Article Summary

While most plant operators manage a utilities system sufficient to supply a small city, many are not aware of proven rental strategies to better manage risks, limit losses and seize unexpected market opportunities.

In particular, ambient air temperature and humidity rise significantly during the peak summer months, relative to winter conditions, which adversely affect major heat exchange equipment throughout the plant. Often quite significant deterioration in performance forces plant operators to make some unpleasant choices, chief among which is a reduction in unit throughput. Owing to the integrated nature of major refinery and petrochemical processes, such problems at any unit usually force both upstream and downstream units to  also cut production.

Market demands often peak during the summer. For example, gasoline sales are highest when ambient conditions 
force production bottlenecks throughout the refinery. These scarcities drive refining margins up significantly, thereby creating huge economic incentives to restore unit capacities. 
The magnitude of monthly economic losses caused by production cutback can easily equate to millions of dollars.

Temporary seasonal strategies
This article examines seasonal cooling problems and issues that commonly occur every year, and how owners have justified acquiring engineered solutions to solve emergencies and production shortfalls in such instances. Additionally, the benefits of employing rented equipment, best practices and results that have been achieved are presented in several examples.

The chief merit of the rental model for solving seasonal cooling problems is that solutions can be deployed at short notice, often within a month or less. The main requirements are:
• Engineering services to develop all feasible alternatives and the benefit-to-cost ratio in each case
• Ready availability of process equipment that has been fabricated and maintained in a manner fully consistent with industry best practices
• Transportation and field assembly, with full cognisance of applicable safety and environmental standards
• Full documentation of process and equipment design details; emergency, startup and shutdown procedures; operator training materials; and all pertinent details to help ensure conformance with management of change and process safety review criteria.

In the past, many operators have not expected that seasonal or temporary projects relying on rental equipment could successfully meet such requirements. This is simply because most players in the equipment rental industry either have not emphasised such aspects or face difficulties in adhering to stringent industry requirements, thereby precluding their participation in the development of systematic, sound solutions.

It is useful to think of temporary solutions for problems in three categories:
• Emergencies These are situations where the failure of crucial equipment must be rectified immediately. Replacement by a suitable equivalent is the best alternative in such cases
• Planned outages Here, major parts of a unit (or the entire process unit) are scheduled to be taken out of service for routine maintenance. The degree of the challenge faced is directly related to the impact such outages have on the rest of the facility. One solution can be to cool and divert the unit feed to temporary storage while the unit is out of service, thus allowing upstream units to stay online. Otherwise, it is imperative to take all possible measures to minimise the duration of the outage by expediting unit depressuring, cooldown, degassing and comfort cooling to enable expeditious repairs
• Process enhancements Often, unit performance (capacity or quality) degrades seasonally during summertime, when ambient air and cooling water temperatures are at their peak. Systematic elimination of the resultant cooling bottlenecks can help restore unit performance to levels seen only during the winter months.

To better understand the importance and impact of these operational issues, one must first understand the larger economic and regulatory factors driving these operational issues.

Challenges addressed by rental strategies
In spite of an ageing infrastructure, the petrochemical and refining industries must meet increased consumer demand, adhere to stringent regulatory oversight, respond quickly to volatile market conditions, and operate within strict safety and environmental limits. They must meet all of these expectations under the watchful eye of citizens in their communities who, while they have easy access to news and information, often lack the technical knowledge to understand the issues and implications of many of the decisions plant managers must make.

To meet increased demand for commodities, and to maximise profitability, mature plants and refineries must work at capacity round the clock, seven days a week. This requires limiting downtime and mitigating outages within safety and environmental constraints. While many of the corrective actions needed in these ageing facilities are temporary, others require longer-term, and sometimes permanent, changes. Rental strategies, often viewed as temporary-only, are being designed by engineering teams and deployed routinely for a few months each year, for many years.

In a commodity-driven business, the ability to respond quickly to market fluctuations often means the difference between profit and loss. Prices fluctuate during peak usage periods, weather events, extreme seasonal climate changes, variances in regional demands and unexpected economic downturns. Operators must have an arsenal of just-in-time tools to adjust the plant’s operation — all within accessible maintenance budgets.

Refineries and plants located in regions susceptible to events such as hurricanes, tornadoes and earthquakes may also need to combat emergency situations. Tools often deployed in such situations include generators, compressors, air dryers and dehumidifiers.