Cost-Effective Solution for Refinery Cooling Towers Case Study

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Cost-Effective Solution for Refinery Cooling Towers

Background

A major oil refinery in the western United States, a long-time Philadelphia Gear customer, had developed a problem over the course of the last 10 to 15 years. They had replaced a number of cooling tower drives, and were accumulating the used ones on-site, with no clear idea as to their final use. Should they be rebuilt? Scrapped? Or perhaps replaced and put back into storage?

The oil refinery used their cooling tower drives to chill condensed steam generated by the manufacturing processes - typically about 10 units at any given time. These are closed-loop systems, so the steam temperature must be lowered prior to it being reintroduced into the production cycle.

Over this same 10 to 15 year period, the refinery had gone through a protracted downsizing effort. They no longer had the resources to inspect and repair the drives on-site, and hadn't made the decision to have them inspected/repaired by an outside service provider. Thus, when a unit failed, a new one was purchased and the old one was simply put off to the side. These old units began to accumulate.

Lack of accessibility to the cooling tower drives (due to the average elevation of a cooling tower often exceeding 80 feet) led to poor-to-nonexistent preventative maintenance procedures. Compounding the problem, safety concerns did not allow for inspection of the units while they were running, and the refinery was reluctant to shut units down during the manufacturing process. Consequently, this affected the inspect/repair procedures negatively and tended to leave cooling tower drive failures a mystery.

The Problem

On a routine visit by a Philadelphia Gear sales representative, the customer inquired about purchasing new units to replace some of their aging models. The customer had three different manufacturer's drives in use. Several of the cooling tower drives had either become noisy, or were above acceptable vibration thresholds.

Rather than quoting on new equipment, the representative opted for a visual inspection of four units that had been shelved during the downsizing period. Even though none of these four were Philadelphia Gear drives, he concluded that the units could still be salvaged, and sent them to the Houston Regional Service Center for a complete inspection. The customer decided to wait for the results before having the new drives quoted.

The Solution

All four enclosed cooling tower drives were sent to Houston for cost/benefit analysis on repair versus new. The units underwent the following procedures:

• Disassembly, cleaning and inspection

• Magnetic particle inspection of all gear elements and housing (a sophisticated black light test revealing pits, cracks, etc.)

• Dimensional inspection of housing

• Visual inspection of rotating elements (gears, shafts and bearings) to evaluate level of deterioration

Test results determined that by combining components of the four boxes, Philadelphia Gear could actually recondition them into two useable units. By taking this approach, the refinery was able to save 40% of the cost that would have been spent on new units.

Once authorization to proceed was secured, the parts to be reused were cleaned and the housing was sandblasted and painted; bearing caps were re-machined as needed; no-load, full speed spin tests were conducted; and vibration, noise, and temperature levels were measured and recorded. A job of this magnitude typically takes six weeks, but the two reconditioned units were shipped back to the customer to re-install on-site in just four. All work included Philadelphia Gear's "best in industry" one year warranty - which includes a six month grace period to actually re-install the unit.

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Refinery Cooling Tower

Refinery Cooling Tower Solution

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