New approach to tank level monitoring improves product storage

Don Horne   

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In the past, McAsphalt found that it could be a difficult and time-consuming process to reconcile the amount of asphalt received/transferred/shipped. Not just asphalt, but the fuels side was a big issue as well, considering the large marine fuel oil and diesel tanks at the facility that required these reconciliations.

Traditionally, manual methods and inventory reconciliation using spreadsheets were used at the facility. Because of the limits on the accuracy of manual gauging and the large size of the tanks at the site, the reconciliation was constantly an issue that historically became just a part of business at the facility.

Daily dips were performed to ensure there were no problems with the tanks and monthly inventory reconciliations were performed. This process involved an hourly employee physically walking on top of each tank and recording levels. Varying weather conditions meant working on top of the tanks was not always safe.

Depending on transfers going on at the facility that day, an employee may have to do these dips multiple times.

This information was then given to a supervisor who would enter it into a spreadsheet and an Enterprise Resource Planning (ERP) system. Due to accuracy limitations and differences in how different employees would dip the tank, the supervisors and office got used to living with a large variance in inventory at the facility.

Key parameters such as product temperature, density and water bottoms (on diesel tanks) were not available on demand. Therefore, any changes with the product in the tank may have been missed if the sampling was no longer current for the tank, which could lead to off-spec product shipment. Also, because there was no live monitoring on a lot of the tanks, there was a potential for logistics to miss inventory needs, resulting in an inability to supply product.

Not only was the reporting more difficult, but because of issues with the accuracy coming into the programs to generate reports, the value of running these reports to provide useful information on the state of inventory in the facility was questionable.

Replacing the tank gauging systems

In this case, a repaired tank was being reviewed with inventory reconciliation to ensure there were no further issues. When the risk management team went to examine the inventory reports to reconcile with movements, the level of accuracy was too low to confirm the repairs had worked. Also, the sporadic information intervals made it next to impossible to make sense of movements versus the accuracy issues mentioned above. The determination was made that what was required was real-time and historical trending available for this tank.

In looking at solutions for the tank in question, a full investigation of inventory reconciliation at the facility was conducted. The risk management team determined that living with errors in inventory was no longer acceptable for the facility given the importance of it to both companies.

A thorough investigation was done into possible solutions from multiple vendors in gauging equipment, controls and automation, and terminal management systems. Through this investigation it was determined the Endress+Hauser solution matched best with the company’s needs. At that time, McAsphalt was only comparing the physical equipment and specifications of the solutions, but over time, it became apparent the added value from having the people at Endress+Hauser as a partner on the project.

The communications options

The layout of the solution considered the physical placement of tanks clustered around key electrical rooms, and wireless industrial data radios were used to reduce installation costs. The radio network was a master/slave star network. A proof of concept test was performed to validate the point-to-point communication paths before the equipment was ordered. It was found that no repeaters were required.

The entire wireless radio network was also set up in the Endress+Hauser office to check functionality. In addition, since the tanks and tank farms comprise large areas, the control wiring to provide communications to the gauging system would have been substantially more expensive than the wireless system.

The solution considered the requirements for accuracy on particular tanks and products, as well as the existing instrumentation that was installed and whether it could be re-used. In general, the larger tanks with higher value products required high accuracy radar level with multipoint temperature probes and pressure monitoring, whereas some tanks required only standard accuracy radar. For a large number of tanks, Endress+Hauser interfaced McAsphalt’s existing instrumentation to the TankVision system using communication gateway modules, such as 4-20 mA to Modbus.

As Ian Notley, project manager at Endress+Hauser, explains, “The standard Endress+Hauser approach was followed from a detailed project kickoff meeting to the project closeout meeting. Key elements included a detailed Gantt chart schedule, for approval drawings before procurement, document control, and FAT before shipment to site. We strived for quick response to customer inquiries/issues, open communications and excellent co-operation in on-site commissioning and troubleshooting.”

There were some issues during in-house testing, so being able to stage the system prior to shipment to site was a major advantage for the project timeline, however no in-house testing is perfect. One example was that McAsphalt requested a third party tank gauging product as a scope change. The interface was developed and tested in-house, but there were some intermittent problems on-site when it was added to an existing network. The issue was resolved only after a period of testing different solutions and isolating the source of the problem. Some software report configuration issues were only uncovered during operation.

Factors such as tank geometry and product within the tank were the largest determinants on how accurate the gauging equipment needed to be. A large diameter tank means any error in the level measurement could result in a large volume difference at inventory reconciliation. An expensive product means any variance in the reporting from the gauging could have a larger impact on the bottom line.

Putting it all together

The technician who commissioned the system also worked on the project through its development. This meant that he knew it inside and out. This saved time and money when co-ordinating with local electricians during the installation as he could easily clarify issues and by the time he was on-site to commission he knew exactly what needed to get done and how to do it.

“Through defining the scope and providing a proposal right through commissioning, Endress+Hauser was with us hand-in-hand. Not only did they provide robust equipment but there was a consistency in the people managing the project throughout the various phases,” said Spencer Segula, project engineer, McAsphalt Industries.

Configuration issues were noticed and addressed when staging, saving time and money instead of having to try to deal with them in the field. Also, the FAT allowed end users to see the product they would be getting and bring up key points which ensured success and acceptance down the road. The documentation, communication and thoroughness when dealing with issues made this one a smooth project rollout. There were some problems that came up, as with all projects, however Endress+Hauser proved they would be able to identify the issues, propose solutions and explain how this would impact the overall project. With everyone at the site having a clear understanding of what was going on, buy-in for the system increased significantly.

A one-of-each type of instrument/device network was wired in the Endress+Hauser office to permit comprehensive testing of a representative subset of the overall system. One problem with powering the radios from the Tank Scanner unit DC power supply was uncovered early during testing and led to additional power supplies being deployed. The main communications interfaces were developed and tested prior to shipment to the site.

The installation

Segula says that the system has performed as designed, and then some.

They now have the ability to tie into automation systems, providing remote access for decision makers and support staff and stock reporting within the gauging system which goes above and beyond the performance requirements from the outset.

Having the ability to better manage logistics and confirm quality control initiatives has strengthened McAsphalt’s relations with their customers. It’s also lowered the risk profile in tank level management. This leads to fewer incidents, which means more uptime and the ability to service customers.

“We have improved the day-to-day operations for employees by allowing real-time tank monitoring and tracking of movements,” says Segula. “This has removed a lot of the pressures of trying to make heads or tails of inaccurate inventory reconciliation data while also lowering the overall risks associated with tank level management.”

Based on the success of the installation at the Windsor facility, Endress+Hauser was awarded a tank gauging system at an asphalt distribution plant facility in Manitoba.

With automated systems becoming more and more of their daily operating strategy, McAsphalt plans to import the data from the system to be used as needed. Because of the expandability of the systems, they’re looking at taking full advantage of all the information available from the system by adding more instrumentation to their asphalt tanks.

“In dealing with Endress+Hauser, we felt we didn’t just have an equipment vendor but a partner in the project,” says Segula. “By having this close communication, consistency in who we dealt with and shared investment in the success of the project, we saved time, money and extra work associated with companies that think on a transactional basis.

“For this reason, we have a continued relationship with Endress+Hauser as a preferred partner for process instrumentation and automation.”



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