Gas compressor plants for one of the US’s largest suppliers of industrial, medical and specialty gases use oil/water heat exchangers to cool compressor lubricating oil.
Oil is on one side of a heat exchanger and cooling water on the other side. Some of the plants have open loop once through cooling systems, with discharge back to a river or lake. If a heat exchanger leaks oil to the water side, it could pollute the environment and/or violate their discharge permit.
Other plants are closed loop with cooling towers where an oil leak could cause decreased heat transfer efficiency from bacterial growth, increased chemical cost and more frequent blow-down, and the oil could evaporate to the atmosphere and/or be discharged through blow-down to the environment.
After a recent oil leak, the company started a project to review the heat exchanger maintenance practices companywide. Their goal was to be pro-active, thereby reducing risk of unmonitored discharges. Early in the review they decided the best solution was to immediately install continuous oil in water monitors.
Some of the ageing copper heat exchangers will be eventually replaced with titanium to help prevent corrosion, but that will be a costly and lengthy effort. Continuous monitoring will help the individual plants continue without the early added expense of replacing heat exchangers.
Turner Designs Hydrocarbon Instruments’ TD-1000C on-line oil in water monitor was chosen because of its very high sensitivity to the compressor lube oil and its low maintenance record in similar applications. Turner’s applications lab tested the Mobil DTE oil to a detection limit of 0.4ppm and gave the customer the confidence to purchase.
Since the TD-1000C detection limit is much lower than the discharge limit of any of their compressor plants the monitor can provide early warning of a leak well before it becomes a major problem. This feature allows the plant to schedule heat exchanger maintenance well in advance.
Furthermore, in plants with multiple heat exchangers on a single loop, if a leak is detected at the discharge end of the loop, strategic samples from each heat exchanger can be injected directly into the TD-1000C with the provided syringe to quickly locate the leak.
Turner Designs Hydrocarbon Instruments was chosen because of their technical competence and understanding of the application plus their sample test capability before the sale.