The importance of mechanical BoP systems

BoP systems include:

• Compressed air
• Service water
• Seal water
• Potable water
• HVAC
• Cooling (water, glycol, …)
• Steam
• Lubrication
• Fuels (diesel, fuel oil, natural gas, propane…)
• Fire protection and detection
• Station service power
• Lighting and receptacles

Since these systems aren’t considered key components of the main process, they usually operate behind the scenes. They seemingly have minimal impact on production, efficiency or profit and, therefore, attract very little attention until one malfunctions.

Small systems, large impact

Although they may look simple and secondary, BoP system design, operation and reliability have significant ramifications on the entire plant, as each of them is generally connected to several key pieces of process equipment. A failure of a single BoP system could ultimately bring down a main process or entire plant. A few common examples include:

• The loss of cooling or HVAC may cause key process equipment to overheat, triggering high temperature alarms and eventually emergency stops.
• The loss of compressed air may prevent control valves from actuating, halting operation of the main process stream.
• The loss or poor quality of lubrication or gland seal water will eventually damage rotating equipment and pumps, leading to unplanned outages or prolonged shutdowns to perform appropriate maintenance.

Furthermore, BoP systems service not only the main process equipment and systems, but they also interact with one another. This means that a single BoP system failure may have a cascading effect, as it will lead to failures in other BoP systems, thus compounding the potential impact on the main process equipment.

As an example, the cooling water loop is commonly used to maintain proper temperature in air compressors or lubrication systems. When cooling capacity decreases in the loop due to a pump failure or clogging, this will eventually affect the lubrication and compressed air systems, thus causing a ripple effect on more process equipment than only those serviced by the cooling loop.

Looking at the process and instrumentation diagrams (P&IDs) is a good way to understand how utilities are connected to the main process equipment, so you can evaluate the potential consequences of utility failure. Performing a failure mode and effects analysis (FMEA) is the first step in determining where efforts should be invested to increase plant reliability.

Potential impacts

While an unexpected plant shutdown may be the worst possible outcome, the potential consequences of BoP equipment failure are numerous and quite diverse:

Safety

Some systems, such as fire protection and detection, must be well maintained to function properly and protect personnel.

Other systems, such as steam and compressed gases, contain a significant amount of energy (temperature and pressure) that could be released in an uncontrolled and dangerous way when components fail.

HVAC systems play a key role in both the safety and comfort of the work environment by maintaining temperature and humidity levels and removing dangerous gases and particulate.

Performance and quality

Main process equipment needs to perform at its best and, to do so, must be supported by the applicable balance of plant systems. Less than optimal lubrication temperatures, compressed air pressure, etc. may not cause the shutdown of main process systems but may lead to subpar performance or quality of the process and its products.

Energy efficiency / recovery

BoP systems may use a lot of power to operate (an air compressor is only about 15% efficient), and it’s paramount to design and operate them properly to avoid impacting the energy bill.

Cooling loops are also key in reducing heating and cooling loads in a plant. When designed and maintained properly, balance of plant systems will operate efficiently and can significantly reduce operating costs.

Maintenance time and costs

Improper design, operation and maintenance may lead to increased maintenance costs (both direct and indirect). Equipment with poor lubrication or temperature control will wear faster and require more time and resources to maintain and require premature replacement.

How to prevent BoP systems from affecting plant operation

To prevent BoP systems from negatively impacting plant operations, it’s important to properly design, maintain, tune and upgrade those systems.

Design

Through proper equipment selection, implementation of relevant redundancy or adequate sizing of control and safety devices, the design of BoP systems will ensure that the entire process can run smoothly, efficiently and safely for a prolonged period. Decisions usually have the lowest cost impact at the design stage because they don’t require costly retrofits.

BBA has extensive experience in designing BoP systems of all kinds and in various sectors, such as industrial plants, power generating stations and mining facilities. Our team has worked many commissioning and start-up hours, which enables us to integrate valuable lessons learned into our design.

Maintain

As with any other mechanical equipment, proper and regular maintenance are key to prolonging its life. BBA’s engineers and field service technicians can help develop a maintenance strategy for the equipment and systems.

Tune

Proper commissioning of each system will make sure the installation conforms to the intended design and ensures the system operates within expected parameters. Pump operating points, control or safety setpoints and control loops must be adjusted with care.

BBA technicians and engineers spend an average of 30% of their time in the field to analyse and tune these systems. Our knowledge is just as much practical as it is theoretical.

Upgrade

Processes are modified over time and system performance degrades over time. BoP systems need to keep pace and supply the new quantity or quality of utilities required. The correlation between process and BoP upgrade is far from being linear and, therefore, must be evaluated on a case-by-case basis.

BBA can perform site surveys on operating systems to determine required upgrades or pinpoint root cause issues when clients are facing issues with their BoP systems. Our engineers can propose various solutions to either correct, improve or replace equipment and components, always having our clients’ best interests in mind.

We know these systems may not be your top priority, but that’s why we’re here to help. Our team can assist you in managing your BoP systems so you can operate your plant without having to worry (too much) about it.