Ergon's Letter after Twisted Tube Bundle Cleaned

National Heat Exchange Cleaning Corp.
Attn: Mr. Greg Sponseller
156 Nulf Drive
Columbiana, OH 44408

Ref: Twisted Tube Bundle Cleaning

Dear Mr. Sponseller,

In March 2006 Ergon West Virginia, Inc. shipped a twisted tube bundle to National Heat Exchange’s Columbiana facility to have the tube ID’s and OD’s cleaned. Due to both the 30° triangular twisted tube pattern on a 0.886 in pitch and to the viscous Vacuum Resid service on the shell side, past attempts of cleaning the OD of the tubes have been ineffective.

Previous cleaning efforts at EWV included circulation of diesel fuel, circulation of a heated cleaning solution, and insertions of high-pressure hydro-blasting lances in between the tube OD’s over a period of days. All cleaning methods resulted in displacement of the grease rather than oil removal. When approached by NHE we were at first skeptical of the predicted cleaning results but we were also especially interested in NHE’s Mobile Cooler Cleaner. The combination of the high volume cleaning flow, the use of heat and solvent, the rotation of the bundle during the cleaning process, and the multiple spray bars w/ adjustment capabilities for the best spray patterns had us intrigued.

The service of the AFS bundle is a desalted crude atmospheric tower feed vs. vacuum residual effluent. In 1999 the original E shell was converted to an F shell (shell modifications were not required) housing a new twisted tube bundle and since it was put in operation neither the design heat duty of 6.8 MMBtu/hr nor the clean heat transfer rate of 35.2 btu/h*ft2*°F (eff. Surface A = 3800 ft2) has ever been obtained. In analyzing the performance of this bundle after the NHE cleaning four (4) timeframes were chosen: before and after cleanings in both 2004 and this year. The 2004 cleaning included three (3) consecutive days of cleaning the tube OD’s via a high-pressure water lance and cleaning the tube ID’s via a special hydro-blasting lance tip that was designed for twisted tubes. This year’s cleaning utilized NHE’s patented MCC method.

The results are presented in the table below.

Table 1: E-107 Performance Comparisons

One month after cleaning the exchanger’s performance remained substantially better than
compared to pre-cleaning: Duty increased by 40% and the heat transfer improved by 64%. Also noted is an improvement when compared to previous cleaning methods: Duty increased by 21% and the heat transfer improved by 24% (when compared to the “post ’04 cleaning” timeframe).

In summary, Ergon West Virginia, Inc. is now seeing the best performance of this exchanger since its installation. The cleaning completed by National Heat Exchange has improved heat transfer and increased heater inlet temperature with resultant energy savings of as much as $70k/yr when compared to the previous cleaning and $110k/yr when compared to a fouled exchanger. Our experience has shown NHE’s MCC to outperform other commonly available cleaning methods for a twisted tube bundle in high-fouling service. The results exceeded our expectations and the service and response by NHE’s sales and support staff were outstanding.

We were very pleased to have been introduced to NHE. Given your proximity to us and your capabilities, we look forward to exploring with you other heat exchanger services in our refinery as well.

Sincerely,

Christine Shorokey
Process Engineer
Ergon West Virginia, Inc.