LaMont One example of a forced circulation boiler is the
LaMont boiler. Such boilers are used in cases where there is high
pressure, above 30
megapascals.
Clayton The
Clayton Industries forced-circulation steam generator does not have a steam drum in the typical sense. A series of small tubes that are part of one giant coil, usually made of steel, have feed water pumped through at great speed. The water is pumped from the top of the steam generator down to the bottom and out. The tubes that are arranged in such a way that the combustion gasses pass around the tube subsequently heating the water. Essentially, the arrangement can be best described as having a large thin walled coil of pipe wrapping around the circumference of a vertical steel drum looping around and down until it reaches the bottom. As only some of the water may become steam, it is important to separate the two and send any water back through to absorb more heat. If this separation does not occur, the damage to the system could be costly. If steam goes through the generation tubes inside, the tubes may overheat and become weak, and if water is allowed down into the steam system, corrosion, water hammer, or other ill effects may occur. To combat this, after exiting the steam generator, the mixture is put through a centrifugal
steam separator which does exactly that producing steam that is above ninety-nine percent dry saturated steam. If
superheated steam is desired, an additional coil is run back through the steam generator. To maintain a constant level of water in the steam separator, the feed pump in conjunction with a leveling system is utilized. A great advantage to this system is that steam can be generated very quickly. However, the downside to this system is the complete dependence on a constant supply of feed water. Without the constant supply, the system may be subject to a massive and expensive damage. Operational safety depends on continuous feedwater supply and active circulation. Because the system does not store a large reserve of water, loss of feedwater can result in rapid temperature rise in the coil if combustion continues. For this reason, forced-circulation generators are typically equipped with flow monitoring, flame safeguards, and automatic shutdown systems to prevent overheating under low-flow or no-flow conditions. Clayton steam generators are subject to regulatory safety testing in jurisdictions where they are installed. Such testing may include controlled low-water firing procedures specifically designed to evaluate equipment behaviour under such loss-of-feedwater conditions. In documented testing of this type, a unit was operated under controlled conditions until structural failure occurred, and no steam drum explosion was reported. == Advantages ==