Combat surging energy costs

BioIndustrial fuel bills can amount to between $1 million and $3 million per year, eating up a large percentage of operating budgets. Surging energy costs have facility engineers, managers and maintenance supervisors looking for ways to make plants more efficient. In many cases, the most logical place to start is with the boiler system. You might think of it as getting control of the Steamer, one of three archetype energy-wasting villains – the D-Energizers – introduced in our May cover story (www.plantservices.com/articles/2007/105.html).

The reason? Eight out of 10 boilers are more than 30 years old. They run less efficiently, often are unreliable and might even be in violation of U.S. federal pollution standards. There are still 400 counties in the United States that are considered U.S. EPA non-attainment zones, meaning they don’t achieve current air quality standards. And while the EPA is the highest-ranking regulator of boiler emissions, many state and local governments are enforcing even stricter regulations.

One way to find out whether the boiler in your facility is efficient is to perform a steam audit: a comprehensive analysis of energy used within a facility, process or equipment, including recommendations for energy conservation measures. A steam auditor can work much like a super hero to apprehend the Steamer and eliminate his wasteful effects on your boiler and steam system.

Scope, cost and deliverables

There are two types of steam audits: a simple boiler system audit and a complete facility audit. In a simple audit, a professional evaluates the boiler room, boiler and accessory support equipment, possibly extending the evaluation somewhat into the facility. With a complete site audit, auditors evaluate the boiler system as well as components throughout a facility, including steam traps, piping, valves and steam users.

A simple boiler system audit costs about $1,000, whereas a complete site audit, depending on the number of steam traps, other equipment and the size of the plant, could cost a few thousand dollars. The essential steps are:

• Data acquisition: Identify where and how a facility, process or equipment uses energy, along with costs and utility issues affecting the energy consumption.
• Data analysis: Identify energy conservation measures to make energy use more efficient, less expensive and more environmentally friendly.
• Recommendations: A final report details what was found, a list of areas that need improvement, and recommended actions, usually accompanied by some type of economic justification.

About the auditing process

If your facility recently replaced the boiler system, more than likely a steam audit isn’t needed. However, if the boiler system is more than five years old, the Steamer may have been doing his dirty work for quite a while and a steam audit is highly recommended.

A steam audit can take several days to complete, depending on the type of audit and the size of the facility. A facility need not shut down for the procedure; it’s better that it continue as usual so the auditor can easily spot steam leaks and other anomalies during daily operations.

During a boiler room audit, your mild-mannered auditor will check the boiler controls, the boiler, blowdown and feedwater conditioning to identify inefficiency issues. Auditors use their uncanny abilities to do an inventory of key equipment, looking for:

• Energy-saving methods
• Areas to implement better engineering practices
• Health and safety concerns

In a complete facility audit, an inspector not only checks the inventory of key equipment in the boiler room, but also focuses on potential improvements throughout the energy-using facility, effectively putting the cuffs on the Steamer to bring him under control. The evaluator inspects the boiler, steam flow, pressures, temperatures, air handling, steam trapping, piping ancillaries including valving and insulation, condensate handling and heat recovery. Energy savings are sought through:

• Locating steam leaks
• Heat recovery
• Conservation of flash steam
• Return of condensate

Start at the boiler

One of the first things an auditor needs to determine is the condition of the boiler system (Figure 1). The decision to replace a boiler shouldn’t be based solely on the boiler’s age. Some boilers, even at 70 years old, remain in good condition. However, if the boiler is leaking, heavily scaled, or has outdated burners and controls, it’s probably time to replace it and oust the Steamer from your plant.

If the boiler is in good shape, it might only need efficiency retrofits such as an updated burner or combustion control system, which can save 50% on capital costs compared to a new boiler unit and provide significant fuel savings at least equal to the retrofit cost during the first year.

Auditors also investigate whether the boiler has been overheating. If the boiler overheats, there might be problems with either the boiler’s insulation or gasketing, which could lead to damaged and unsafe equipment. The cost of repairs to correct these types of problems are relatively nominal when compared to the consequences of letting the Steamer flex his energy-sapping muscles unchecked, causing conditions to exist that result in serious safety or mechanical repair issues.

The auditor will perform a combustion test using stack gas analysis equipment to quantify boiler efficiency. This could lead to the recommendation of an oxygen sensor/transmitter in the exhaust gas.

The sensor/transmitter continuously senses oxygen content and provides a signal to the controller, which adjusts the air damper and gas valve, maintaining a consistent oxygen concentration in the flue. This minimizes excess air while optimizing the air-to-fuel ratio and puts the Steamer on the run.