Successful Cleaning Process Requires Team Effort
Customer and supplier mount intensive effort to bring a new, successful cleaning process online.
If you have a part with a particular contaminant, there are a number of suppliers out there with a cookbook solution. However, potential applications and variations of existing applications arise on a regular basis. In many cases, these applications challenge existing knowledge and require considerable effort to find a solution. Developing a successful cleaning process requires persistence and the ability to use all available tools to bring a successful cleaning process online.
The temptation when approaching a new application is to look for parallels, or a similar solution that has been used successfully in the past. In many instances, this approach will lead to a solution, but other problems require a fresh start. In the following case study, the path to a solution required several attempts and the manipulation of several cleaning parameters.
In this case, the challenge was cleaning centrifuge discs used in an oil field application, separating oil from oil sand in preparation for refining. The discs are truncated cones with an approximate diameter of 24 inches maximum and a smaller diameter hole in the center at the top of the cone. These discs are constructed of thin stainless steel and have radial features that space the discs apart when nested in the centrifuge. These features also contribute to the separation efficiency of the centrifuge by interrupting and redirecting the flow of the material being processed.
The centrifuge discs require periodic cleaning to remove a buildup of oil, wax, tar and small pieces of sand that clog the space between the discs, leading to process inefficiency and possible damage to the centrifuge itself because of imbalance and other issues. The previous cleaning process involved soaking the discs in solvent to soften the contaminant and then manually brushing each disc to remove residual contaminants. A mechanized process was sought to reduce the cost of cleaning the discs.
At first blush, the application appeared straightforward. Similar discs had been successfully cleaned using a mechanized process with ultrasonics, but initial cleaning trials using this process were unsuccessful. In an effort to find a quick solution, increased chemical concentration, increased temperature and longer cleaning times were tried using existing chemistry, though these adjustments did little to improve the cleaning process.
The similarity between the two applications was deceiving. The successful application took place in a different part of the world where the contaminants from the oil and sand were much different from those in this case where the contaminant was rich in wax and heavy tar. So the search for an effective cleaning process continued.
A formal test plan was prepared and reviewed. Based on the customer’s need, cleanliness and time test criterion were established. The best process would provide visual cleanliness, with no sign of residue, in a minimum amount of time.