Oil & Gas
20.12.2018
Challenge
What's the challenge?
Demanding requirements in heat transfer applications
Heat-transfer pumps must operate safely and reliably in order to ensure a high level of quality in production processes. Not only are such pumps frequently subject to high loads, but in addition their failure can have serious consequences, especially if hot oil is allowed to escape. For these reasons, operators of heat-transfer systems are very sensitive to any leaks. While hot water normally escapes through the seal in the form of steam – and usually does not cause major damage – any escaping heat-transfer oil rapidly disperses across a wide area and has a high potential for serious damage. Any leaks from thermal oil pumps represent a precarious situation that requires a rapid and effective response. Elevated liquid temperature makes this a challenging task. The solution to this problem is to monitor the rate of leakage in order to detect the early stages of seal wear. That way, pump operators know as soon as a leak starts.
Pumps used in heat-transfer systems are subject to high loads induced by elevated temperatures and large temperature differentials. What’s more, chemical decomposition reactions often occur in the pumped liquid whenever the heat carrier is under high thermal loads. In particular, the chain-like hydrocarbons decompose over time into „low boilers“ and „high boilers“. When the proportion of low boilers becomes too high, there is a risk of pump cavitation. High boilers, on the other hand, accelerate pump wear and occur in numerous forms, from a bituminouslike consistency to highly carbonized products. Both represent a threat to the bearing and shaft seal of the pump. The use of synthetic heat-transfer oil reduces the appearance of low and high boilers, but the low viscosity and lubricity of these materials has other drawbacks. The tribological loads working on the sliding components of mechanical seals is extremely high.
