In todays tough economy, plant asset management (PAM) has become a strategy that is hard to ignore. If applied properly, every aspect of every business in every industry can be optimized. In doing so, however, it is crucial to take issues, opportunities and benefits of each individual business into account i
f the efforts are to yield fruitful results. When applying asset management to processing plants within the hydrocarbon processing industry (HPI), for example, the most appropriate approach varies depending on the application area and whether it is an upstream, midstream or downstream installation. An area where this is particularly relevant is at hydrocarbon terminals, tank farms and storage facilities
that employ leak-detection (LD) and custody-transfer (CT) systems.
At a general level, PAM is associated with managing an assets life cycle. It is a process that can potentially improve operational, environmental and financial performance, prolonging asset life and aiding rehabilitation, repair and replacement decisions through efficient and focused operations and maintenance. In other words, implementing PAM can help improve production reliability while reducing expenses, which has been demonstrated in several studies. According to the ARC Advisory Group, companies are reporting as much as a 30% reduction in maintenance budgets and up to a 20% reduction in production downtime as a result of implementing a PAM strategy. So, clearly, PAM does provide benefits, if implemented properly.
| Fig. 1. Storage facilities and liquid terminals |
can achieve substantial operational and cost-
savings benefits by combining leak-
detection and custody-transfer systems.
Process instrumentation is key to any PAM strategy.
As the name indicates, PAM focuses specifically on the assets related to running a processing or manufacturing plant, and as such, it is relevant for any industry. When applying PAM to the HPI, and more specifically to a liquid terminal or storage facility, numerous aspects and plant operation areas can be assessed: measuring the actual production in relation to quality, quantity, reliability and environmental standards; identifying assets critical to sustained performance; and collecting historical data to help predict future performance and life cycle costs.
While these are only a few examples, they underline the importance that process instrumentation such as valve positioners, flowmeters, temperature and pressure sensors play in PAM. It is the single most important source for controlling, monitoring and measuring overall equipment performance data, field device diagnostics and meter parameterization, all of which are considered key performance indicators of PAM.
Integrating process control and monitoring systems.
One method of optimizing a tank farm or storage facilitys production and distribution capabilities in a way that directly supports the overall goals of a PAM strategy is by taking a critical look at the various systems that make up a complete plant. Wherever possible, it may be beneficial to rethink the way things have been done. Two areas of particular interest in this regard are also two of the most important systems throughout the entire storage facility: the pipeline LD and CT systems.
Traditionally, LD and CT systems have not been fully integrated. They are looked upon as two completely different entities installed and operated independently, offering no measurement parameters to be used between them. Nonetheless, combining these two systems has the potential to provide numerous benefits, especially when looking at it in light of a PAM strategy. Before getting into these benefits, however, a brief description of each of the two systems and their primary functions is required.
Leak detection a must.
From a PAM perspective, a pipeline LD system can be defined as an asset critical to sustained performance. If a product release occurs, the owner or operator will not only lose product, but will also most likely be fined for not detecting the release in a timely fashion or not at all, and may be faced with potentially enormous cleanup costs depending on the release size. In addition, outside factorssuch as government law and regulations, rising energy prices, growing public concern about pipeline network reliability and security issuesall have an impact on how important an LD system is perceived to be. Having an LD system is simply crucial and, therefore, it would be a good starting point to look for improvements related to a PAM strategy.
Many different LD system types are in operation today, but, basically, they can be divided into two main categories: external and internal. External systems, such as hydrocarbon sensing via fiber-optic or dielectric cables, detect leaks outside the pipe. Internal systems, on the other hand, utilize instruments to monitor internal pipeline parameters such as pressure, temperature and flow. Flow measurement is generally considered the most important process in pipeline operation and control for several reasons that coincide well with those of PAM. Most modern electronic flowmeters not only monitor the product flow, but also incorporate features like self-checking diagnostics and the ability to store data for future use.
A complete LD system is made up of two major components: the software and the hardware (process instruments such as flowmeters, pressure transmitters, etc.). LD system suppliers can therefore be divided into three categories, depending on which part(s) they deliver. Some manufacturers supply the software only while relying on the input from existing instruments to provide pipeline data. Others deliver the software and have agreements with third-party instrumentation providers to offer a complete solution, and others again provide both software and instrumentation in one integrated package.
One example of an internal LD system relies on clamp-on ultrasonic flowmeters based on the wide-beam measurement principle and a computer-based modeling package. It consists of one master station that collects and processes data, along with numerous site stations that measure and compute the variables required to run the LD system. The exact number of site stations depends on the pipeline length, but a minimum of two are required, one at each end of the pipe. Apart from the fact that this solution offers both the LD system software and hardware, it can also be easily integrated into a custody-transfer system. Advantages from a PAM viewpoint include the ability to install the instrumentation without shutting down the pipeline (thus reducing total life cycle costs), bidirectional measurement (decreasing operation cost by only requiring one meter to perform measurement tasks) and the capability to identify changes in liquid properties (product quality measurement).
| Fig. 2. Process automation instruments are considered the single most important source for controlling, monitoring and measuring overall equipment performance data, field device diagnostics and meter parameterization, all of which are considered key performance indicators of PAM. |
Accurate product ownership transfer.
As is the case with an LD system, a CT system can also be defined as an asset critical to sustained performance from a PAM viewpoint. Being that a custody transfer system is used to measure the product ownership transfer from, in this case, a liquid terminal to the end-customer, it can mean the difference between making and losing money. Such a system, which is basically just a flowmeter, needs to be accurate and reliable, and it is required to constantly measure to very high standards. If it fails or is prone to performance issues or blackouts, a critical part of a terminal or storage facilitys function is inoperative. This is exactly what is sought to be avoided when utilizing PAM. By having a strategy in place that can diagnose health issues and predict remaining useful life, facility operators can engage in proactive as opposed to reactive maintenance.
Several flowmeter types are available for accurate CT measurement. Each of these has its strengths and weaknesses. Generally speaking, there are no set rules when it comes to choosing which technology is the most appropriate for a specific CT application. It all depends on the operators preferences, installation and accuracy requirements. If a true integration between a CT and an LD system is to take place, however, the employed technology should be the same. So for, say, an LD system, relying on wide-beam ultrasonic flowmeters to be truly compatible with a CT system, they would both have to be based on the wide-beam ultrasonic flow-measurement principle.
As mentioned, LD and CT have traditionally not been combined into an integrated system. Although real-world applications exist where data from a CT meter is used in an LD system, such solutions can hardly be considered truly integrated. This is mostly true for the software-based LD systems that rely on existing or third-party measurement equipment to feed the software with crucial real-time pipeline performance and operation. The instrumentation and software have not been manufactured to work with each other, making it necessary to customize communication protocols, data extraction and information analysis to mention only a few examples. The result is a system that depends on various factors that may or may not be compatible to produce an optimal performance. And this is a strategy that is incompatible with PAM.
The future solution.
In light of PAM and recent HPI product developments, however, truly integrated systems are now available. This has made the benefits of combining LD and CT systems much clearer.
In those cases where a wide-beam ultrasonic CT meter and one of the site stations of an LD system would be located close to each other, substantial cost benefits can be realized. With a combined system, one CT meter is installed that serves two purposes. First, it would be used for product ownership transfer and secondly, it would act as one of the LD system site stations. This would reduce capital costs, maintenance efforts and installation requirements, which are perfectly aligned with any PAM strategy goals.
Another combined LD and CT system benefit based on the same measurement technology and manufactured by the same supplier is the fact that it ensures overall compatibility. Everything from liquid sensing and communication protocol to data extraction and displayed information is based on the same principles. This makes commissioning faster and easier, which potentially minimizes equipment installation and pipeline downtime.
Total cost of ownership (TCO)or total life cycle costs, as it is referred to in PAMis also positively addressed in a combined LD and CT system. First, and as already mentioned, the most substantial upfront savings is achieved because less equipment is needed; secondly, less operator and maintenance training is required since they only need to manage one system and lastly, troubleshooting is made easier because the various combined system components have been designed with the same goal in mind. All these factors contribute to keeping the TCO down, which is one of the main goals of any PAM system.
Ultrasonic flowmeters come with a variety of diagnostic functions that add clear and distinct value to a PAM strategy when installed as part of a combined LD and CT system. One of the major benefits is that the flowmeter reports to the terminal or storage facility operator how the meter is doing, along with reporting the accuracy within the preset limits, and if the signal is strong enough to provide a measurement value, etc. This function eliminates the need for routine meter inspections. Another useful diagnostics tool is the totalizer function. It allows compiling historical data and adding time stamps or interval settings. This way a product amount can be determined, from which a product value can be derived, another important aspect of PAM. Finally, the diagnostic function can, in some cases, also be used to determine product quality variations, thereby enabling operators to look into what has caused the degradation in quality, which is clearly an asset in any PAM strategy. HP
| Fig. 3. When applying PAM to the HPI, and more specifically to a liquid terminal or storage facility, such areas as actual production measurement in relation to quality, quantity, reliability and environmental standards, and collection of historical data to help predict future performance and life cycle costs can be assessed. |
|The author |
||Jonas Norinder is a business development manager at Siemens Industry, Inc. in Hauppauge, New York. He has experience in marketing flow solutions in various industries. Over the years, Mr. Norinder has written numerous articles published in renowned industry-leading magazines on this topic. |