Steam pressure / Sludge drying, Slurry drying, Recycling drying

■ Steam pressure

Steam is generated when water is boiled though, there is a large difference between their volume. For example, volume of steam will be 1,700 times larger than water when steam is generated without adding pressure under atmospheric pressure.
Boilers for creating steam generates steam by adding heat on water within sealed container. The container will not expand, so the steam will get pressure. When amount of generated steam is increased in the same amount of area, pressure will become higher according to amount of the increase. By sending pressured steam through pipes, the steam can reach further. The pressure becomes lower as length of pipes becomes longer.
Adjustment of pressure in steam generating boiler is complicated since fuel, amount of air, amount of water, etc. are needed to be controlled, and these controls are normally done by pressure regulating valves in the second apparatus which are apparatus using the generated steam.

■ Volume of saturated steam

Steam generated in boiler contains small amount of water. Steam which contains water is called wet saturated steam. When seam pipe has a hole, steam is expelled from it. Not only pressured steam is expelled from the hole. Since pressure of water in the pipe is decreased, volume of saturated water expands quickly by becoming steam and expelled together. Part of drain water discharged form steam trap becomes flush steam because of pressure drop, and this occurs because of the same reason as the above.
Specific volume (m3/kg) of saturated water is increased and volume of saturated steam is decreased according to rise in pressure of wet saturated steam. Please refer to the following table for the details.

Saturated steam table
Gauge pressureTemperatureSpecific volume( m3/kg)
(Mpa・G)(℃)Saturated waterSaturated steam


■ Steam pressure and steam flow

Steam flow of saturated steam under the same flow velocity is increased as pressure rises. In other word, steam flow is increased when steam pressure rises in the same pile size.
Pipe size of wet saturated steam is selected to make steam velocity 20m/s or less, and it is decided according to steam pressure(Mpa) and required steam flow(kg/h).

■ Steam pressure and steam temperature

Steam temperature of saturated steam is different depending on pressure, and temperature rises when pressure is increased. Temperature becomes low when pressure is decreased. Change in steam temperature can be done easily by adjusting pressure regulating valve. However, steam flow is also increased together with temperature rise when pressure is increased. By decreasing pressure, steam flow is also decreased together with lowering of temperature. These affect to amount of fuel consumed in boiler and fuel cost will be lower when steam is used in as lower steam pressure as possible, so running cost can be kept low as a result. 
KENKI DRYER uses saturated steam as its heat source and temperature can be controlled easily depending on each material to be dried by adjusting steam pressure. However, even adjustment of steam pressure changes steam temperature, it also changes steam flow and affect to fuel cost of boiler as well.

steam pressure sludge drying kenki dryer




Comparison between heat pump type KENKI DRYER and previous KENKI DRYER


Comparison between heat pump type KENKI DRYER and the previous type which uses steam generated by boiler (saturated steam) is the following. Values are not actually proofed values but estimated values.


Amount of carbon dioxide emission from boiler
 Petroleum hydrocarbon
gas consmption
 Heating value per unit × emission factor × 44/12
 Amount of CO2 emission (tCO2/h)
Boiler fuel58×0.0023380.1356
Amount of carbon dioxide emission from compressor
 Electricity consumption (kwh) 

Emission factor after adjustment

 Amount of CO2 emission (tCO2/h)
Compressor input power125×0.0003470.0434



running cost ,CO2 emission reduction heat pump sludge dryer 11/07/2020


Heat pump dryers


■ Heat source, Saturated steam


Even KENKI DRYER uses only saturated steam as its heat source, it is outstanding in safety and hygiene point of view with its unique drying mechanism based on combined use of conductive heat transfer method and heated air method. Since steam is a stable heat source, quality of discharged material after drying is also stable and equable. Maximum allowed steam pressure is 0.7Mpa and adjustment of steam pressure, adjustment of drying temperature in other words, can be easily done. Saturated steam is commonly used in many factories so that it can be said as a familiar and handy heat source. In comparison with drying methods using burner or hot blasts, saturated steam method is an indirect drying applying heat exchange via pipes that steam is passing through, therefore, it hardly burns the materials and is outstanding in safety and hygiene point of view.


Why low-temperature is used for drying? / KENKI DRYER / sludge drying, slurry drying, feed drying

Heat source, Steam


Please consider KENKI DRYER for drying of sticky materials, adhesive materials and materials in liquid state that no other dryer can deal with.
Initial, running and maintenance costs are low because of its simple structure based on internationally patented technology.
For sludge drying, costs of our dryers are estimated to be retrieved within 2, 3 years by reducing industrial waste disposal cost.
For raw material slurry drying, laborious works of manual operation will be decreased significantly by replacing box shaped compartment tray dryer with our dryer
In case of organic wastes drying, the waste can be recycled as fuel, fertilizer, soil conditioner and feedstuff after being dried.



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