Background
A Western Providence integrated Refining and Petrochemical Company is home to the world's largest High Olefins Fluid Catalytic Converter (HOFCC) Unit. The HOFCC unit converts both heavy and light oils to gasoline and a wide range of other refined distillates. In addition, homo polypropylene (PP), block PP, and propylene oxide (PO), a raw material for urethane, are produced from propylene which is supplied from the HOFCC.
Problem
The Splitter Reboilers (vertical tube and shell heat exchangers) contain 4,982 tubes each. The company requires only one exchanger to operate the process while the second exchanger is utilized as a standby exchanger until the in-service exchanger loses efficiency, requiring operations to switch to the standby exchanger. Utilizing their on-site contractor, which provides 20,000PSI and 40,000PSI conventional hydro blasting methods, the client generally spends up to 60 days cleaning the once in-service exchanger while the standby exchanger is in-service. The on-site contractor performed repeated cleaning of the 4,982 tubes in order to achieve the desired level of cleanliness so that an IRIS Inspection of the exchanger tubes could be performed. Since 2009, the client had only been able to perform the IRIS inspection twice. Most often, the client would accept the exchanger as-is after many repeated cleaning attempts and returned the exchanger back to service; largely because of the necessity to take the standby exchanger out of service due to reduce heat transfer efficiency.
Objective
The client had attempted many times to achieve a consistent level of cleanliness to reach the criteria required for IRIS Inspection by utilizing several different contractors with a variety of non-automated, semi-automated and automated cleaning systems from local water jetting companies. On some occurrences the client wasn't able to achieve 100% cleaning of all the tubes due to the amount of fouling and toughness of the accumulation. Typically, the client had contractors spending as much as 60 days cleaning either one of the exchangers that was out of service. There were those occasions, that the client had to take a complete unit shutdown because the exchangers did not provide enough heat transfer to run the process. The client approached RefSol who had on other occasions provided a more thorough and faster cleaning on other process equipment within the complex. The client tasked RefSol to provide an solution that would do two things: 1) reduce the total cleaning time normally required and 2) achieve a level of cleanliness that would meet the requirement to enable them to perform IRIS Inspection.
Solution
RefSol was given the opportunity to evaluate the exchanger and review the historical data provided from the client; and proposed a two-step cleaning process solution. The first step would be to utilize the Hydrokinetic cleaning method to quickly unplug and remove the majority of scale and accumulation from the tubes. The next step would be to utilize the Armadillo Tube Cleaning System that is also exclusively provided throughout the region by Refinery Solutions. The purpose of using a combination of two methods was to use Hydrokinetic to clear/open the tubes to remove the vast majority of foulant quickly; thus enabling the Armadillo unit (rotating tube lance system) to polish the tubes quicker and ultimately provide a much faster turnover of the cleaning process.
Result
The combination of the two cleaning methods resulted in an acceptable cleaning level that met the requirement for IRIS Inspection. No re-cleaning was necessary; a first for the client that such level of cleanliness was achieved on the initial inspection after cleaning. In addition, the total cleaning time was reduced from on average of 56 days to just 10 days utilizing just one Hydrokinetic™ and one Armadillo cleaning unit. Lastly, now that the cleaning can be performed in far less time that in the past; it has eliminated the occurrences that resulted in requiring the unit to completely shut down because previously the cleaning could not be completed to achieve the desired cleanliness level to enable the unit to switch in-between exchangers as originally designed.