When you look at supporting industrial utility systems like ammonia refrigeration, you may wonder how often you might actually encounter them. They appear far more in your daily life than you realize. Look at the rooftop of an industrial facility and see if you notice orange pipes or windsocks. It is likely that this facility has an ammonia refrigeration system. Now, when it comes to the maintenance of these systems, there are a few pain points that tend to plague facilities more than others.
These systems are decades old in most cases, many around 20–30 years old, and tend to require human labor occasionally. By comparison, the average industrial boiler system in the United States is around 30-40 years old, and many of these systems require large amounts of human interaction more often. The thing both these systems share is a lower level of automation, utilizing control panels dependent on relays and contactors to implement control schemes.
Incorrect Sequencing Causing Inefficiency:
Not only primitive automation, but the inability to adapt to changes in demand or load can present a challenging issue. This can often result in incorrect sequencing equipment due to simple control implementations, leading to lower overall system efficiency. A common instance of incorrect sequencing is having the largest piece of equipment either always running or brought online when demand is lower, which can be less efficient in its operation and energy consumption. Keeping in mind these systems can also be slow to start or restart if personnel are not quickly notified when a fault or issue occurs.
Lack of Integration into Larger Control Systems:
Even if a modern system has been implemented, it is less likely that it is part of a BMS (Building Management System) or DCS (Distributed Control System) which could better control these utilities based on what is actively happening in the control system for the entire facility.
Benefits of Adding a Modern Automation System to an Existing System
Adding the consistency and reliability of a modern automation system has the potential to positively impact an existing system. Accommodating the need for increased safety, higher energy efficiency, longer equipment life, enhanced diagnostics, and being able to operate the system with a smaller team are just some of the benefits.
Utilizing modern control system implementations can be realized through redundant architecture and communication protocols that use safety messages, meeting SIL-3 (Safety Integrity Level) in most applications.
Leveraging technologies such as VFDs (Variable Frequency Drives), which allow for a more gradual start to pieces of equipment like compressors or motors for driving fan belts on condenser towers, help achieve these benefits. Using VFDs raises the energy efficiency of the system significantly over conventional motor starters and leads to tangible savings in energy costs. Depending on the size of the system, some utility providers may be willing to fund a portion of the project if the energy savings are large enough to impact their bottom line.
Longer Equipment Life / Enhanced Diagnostics / Able to Operate with Limited Manpower:
Continuing to build on efficiency, PLCs (Programmable Logic Controllers) allow for better equipment sequencing and monitoring. Having the added benefit of being able to be incorporated into a large DCS or BMS, the amount of manpower needed decreases as these systems can monitor and operate multiple pieces of equipment simultaneously.
Where is the Industry Heading for These Utility Systems?
Regulations and standards from outside organizations are putting pressure on many facilities to modernize their systems to remain within compliance. This presents a unique opportunity to add a modern control system while performing other upgrades. Systems such as ammonia refrigeration are not only here to stay, but increasing in implementation as other refrigerants are phased out.
Boiler systems will need to better regulate emissions in the near future to remain within defined parameters, as many of them rely on natural gas as their fuel source, requiring upgrades of the control systems to improve fuel efficiency and lower emissions.
Remote monitoring is playing a large role as the need for smaller boiler systems that are distributed throughout a plant is increasing, requiring an investment in controls infrastructure to manage the growing network of equipment with a limited staff.
A consistent theme throughout, the desire for enhanced safety is being expressed in the United States after some larger ammonia accidents in recent years. Charging less ammonia to the system and a better control system will help achieve those goals.
Related Experience with These Systems in Industry
Hand-in-hand with industry direction, relative industry experience presents its own set of challenges. From trying to find prospective employees with the correct licenses, inexperience impacting productivity, and overall safety being the utmost concern, these facilities are truly positioned for automation solutions as the need for monitoring increases and available workforce continues to decrease.
It can be difficult to find employees that have the necessary licenses to care for and maintain systems that have a low level of automation. Many systems dependent upon their size in the case of steam generation, do not need to have operators constantly checking the system but require that a licensed individual be present onsite.
Inexperience Decreasing Productivity:
The issue that occurs is the need to constantly monitor or control these systems pulls operators away from other tasks which lowers productivity. Having human involvement in some systems can often be more dangerous than a control system. In the case of ammonia refrigeration, an operator opening the wrong valve could send high-pressure liquid ammonia to a compressor or burst a pipe, leading to a large release of ammonia due to inexperience or unfamiliarity with the system.
Similarly in boiler systems, operating the wrong valve or equipment could lead to a catastrophic failure due to high pressures handled in steam generation facilities. It’s not impossible for these types of issues to occur in a control system, but interlocks can be designed to prevent accidental operation of equipment that cannot be used for safety reasons. It’s far more convenient, and when speaking of industrial utilities, can be far safer to operate a system remotely than being onsite to operate the equipment.