Steam generator (boiler)

A steam generator is a form of low water-content boiler, similar to a flash steam boiler. The usual construction is as a spiral coil of water-tube, arranged as a single, or monotube, coil. Circulation is once-through and pumped under pressure, as a forced-circulation boiler. The narrow-tube construction, without any large-diameter drums or tanks, means that they are safe from the effects of explosion, even if worked at high pressures. The pump flowrate is adjustable, according to the quantity of steam required at that time. The burner output is throttled to maintain a constant working temperature. The burner output required varies according to the quantity of water being evaporated: this can be either adjusted by open-loop control according to the pump throughput, or by a closed-loop control to maintain the measured temperature.

They are used as auxiliary boilers on ships.

Steam generators (boilers) have the potential to injure personnel or cause large amount of damage to property. Boiler Inspections are required by law to ensure proper safety mechanisms are functioning to specific standards. A few safety mechanisms inspectors check are the nameplate, relief or safety valve, control safety devices, expansion tanks, and visual inspections.

Inspectors inspect the nameplate to ultimately determine what safety mechanisms that specific boiler contains. The nameplate also states what year the boiler was made, who certified the boiler, type of boiler, max operating temperature, max operating pressure, input firing rate, output firing rate, and blow off pressure of the relief or safety valve.

The relief or safety valves function ability is important due to the possible chance of overheating or pressurizing a boiler. Overheating or over pressurizing a boiler can cause a boiler to explode.

Another safety mechanisms of boilers is the control safety devices. One control safety device is the low water cut off switch. This device detects the amount of water in the boiler. A low amount of water flowing to a boiler could potentially cause a boiler to overheat ultimately damaging the boiler. The safety mechanism used to control firing rate of boiler is called the operating switch. This operating switch also has the ability to turn the boiler on and off. This switch is inspected to ensure proper functioning ability. Pressure control devices include the operating switch and the high temperature limit switch. These prevent over pressurizing of the boiler by controlling firing rate and providing an automatic shut off if temperature reaches beyond safe operating conditions. Expansion tanks are used in boilers to allow the expansion and contraction of water to travel somewhere.

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Wikipedia