Cleaning Heat Exchangers Prior To Pulling

The Challenge

A major U.S. refinery had difficulty extracting and hydroblasting heavy oil exchangers (i.e. crude vs. resid service). The process posed many safety challenges and typically required 3-5+ days to disassemble, hydroblast and reassemble each exchanger.

The Solution

This refinery began exploring options for cleaning an exchanger prior to hydroblasting with the intent of reducing hydrocarbon exposure during the extraction, as well as expediting the hydroblasting process. As a test case, the refinery chose to pull and hydroblast two preheat exchangers (crude on tube vs. resid on shell) in parallel service.

Both exchangers had been in service for more than a year since they were last hydroblasted and it was judged that they were significantly fouled with inorganic contaminant (metal oxides and coke). Given the nature and extent of the fouling, the refinery felt it would be best to pull and hydroblast both exchangers rather than attempt to just clean and return to service.

Testing

Exchanger 1 was pre-cleaned by circulating light cycle oil, followed by a steam purge.

Exchanger 2 was cleaned using Refined Technologies’ patented QuikTurn® chemistry and Vaporganic® cleaning process. Both the shell and tube sides were cleaned simultaneously and the process was completed in less than 4 hours. The bundle was extracted immediately after the QuikTurn cleaning process was completed.

Photo 1 shows that following the light cycle oil flush, a significant amount of asphaltene contaminant remained adhered to the tubes of Exchanger 1. Even after hydroblasting, caked contaminant was visible in the core of the exchanger.

Cleaning Heat Exchangers Prior To Pulling

Cleaning Heat Exchangers Prior To Pulling

Photo 2 was taken following the QuikTurn cleaning as the exchanger was extracted from the shell. It is clearly evident that the amount of contamination has been significantly reduced. Hydroblasting of this bundle yielded only a handful of dry, inorganic flakes that were easily washed off of the bundle.

Similar results were obtained in another large Gulf States refinery where they found precleaning with QuikTurn reduced their hydroblasting time by 80%.

The Results

As a result of this direct comparison of pre-cleaning methods, this refinery concluded the following:

  1. Pre-cleaning exchangers with QuikTurn prior to hydroblasting allows for a safer extraction & reduced hydroblasting time.
  2. Pre-cleaning exchangers with QuikTurn improves the predictability of hydroblasting time (out of service time).