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Fluid Control Engineering

For Steam System : Efficiency Improvement of Steam System

The principles for operating steam use equipment efficiently are as follows:

  1. As long as its process allows, use as low steam pressure as possible.
  2. Supply dry saturated steam during operation.
  3. Remove condensate as promptly as possible.

When supply steam is moist steam, its steam enthalpy becomes smaller than a saturated steam.
The lower the pressure is, the larger the latent heat of steam becomes. Then the lower the pressure is, the larger decrease rate of steam enthalpy become at the same degree of moisture.

If moist steam is supplied to equipment, the output of the equipment declines since condensate film of the heat transfer surface become thick.
In many cases, condensate contains foreign substances, such as scale, or paste which is used at the time of plumbing. These foreign substances adhere on the heat tranfer surface and reduce the output of equipment further.

In these ways, condensate prevents efficient movement of equipment. In addition, since it does not have heating capability since heating work is finished, it is necessary to discharge it out of equipment as promptly as possible.

1. Efficiency Improvement of Steam System

For energy saving, it is very important to improve from the origin the present condition of heat use which has been neglected for a long time.

Consider energy saving not simply but, from the aspect of the quality and productivity, with going back to the most fundamental question such as "how what kind of heat gives is best? to pursue efficiency improvement. Then big "energy saving effect" will arise as a result, in addition, a complex merit can be also obtained, we believe.

2. Improvement of Steam Quality

When advancing the efficiency improvement of the steam system, "steam quality" is required to consider. Steam quality can be shown as the amount of moisture (the amount of condensate) contained in steam concretely, and expressed with "degree of dryness" or the "degree of moisture."
As described in the previous page, condensate which occurred during steam transportation is removed by the layout of piping and installation of a suitable steam trap.
By this, steam contains less condensate is supplied to the inlet side of steam use equipment. Furthermore, in order to improve the steam quality further, install a drain separator (steam-water separator) to make steam close to saturation dry steam as much as possible.
DS-1 and DS-2 drain separators can separate condensate efficiently using the centrifugal force which generates steam with its passage shape. Separated condensate is brought together into the lower part of the drain separator, and is discharged by the steam trap.
Since condensate removal not only improves of steam quality but prevents erosion of valve seat of a reducing valve or a control valve, it is an ideal to install drain separators in front of the inlet side of main equipments.

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