Typical applications include: autoclaves, industrial ovens, retort and other batch processes
While it is desirable to have combustion equipment with a high turn down in order to avoid excessive cycling and the resultant loss of efficiency, it is not advisable to operate boilers close to their minimum output for prolonged periods. Industrial boilers are at their most efficient when operating around 70% of nameplate capacity, therefore, factories that experience highly variable steam demand would likely benefit from sizing boilers for their average load (instead of peak load) and incorporating a steam accumulator to smooth out the peaks and troughs in demand for steam.
When high-pressure, saturated water is exposed to low pressure, a percentage of this water will flash off into steam through using the remainder sensible heat in the water. The proportion of flash steam (kg of steam/kg of water) depends on the difference in pressure at which the hot water is exposed.
When plant experiences low steam demand, and the boiler can generate more steam than it needs (i.e. at the maximum continuous rating of boiler), the unused, excess steam is injected into water that is stored under pressure inside the accumulator.
After some time, the temperature of stored water will increase to saturation temperature in line with the operating pressure of the boiler. When steam demand is high, in that it exceeds the maximum capacity of the boiler, it creates a drop in pressure in the accumulator which results in some of the water flashing into steam. Consequently, it can achieve the high steam demand without affecting the normal boiler operation.
If the steam demand is higher than the boiler capacity, the pressure drops in steam accumulator where the water is stored at saturation temperature. The pressure drop in the accumulator results in flash steam being generated, which offsets the high load requirement without affecting the normal boiler operation.
When the overload condition has stopped, it is subsequently followed by off-peak load, allowing excess steam to be injected into the accumulator. At this point, the accumulator will be ready to handle the next overload in demand. Consequently, the accumulator allows the boiler to achieve its preferred operating pressure and maximum efficiency.