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  1. Joesteam

    Super heated steam to blame?

    Everyone is right, going back 30 years to my engineering class: Q=UA(dT). With superheated steam the dT is greater, however the U is MUCH smaller, hence the lower heat exchange rate with superheat vs. saturated steam. A gross estimate of the 'U' for superheat I have seen is 16 while that for...
  2. Joesteam

    Super heated steam to blame?

    I was always taught that superheated steam has lower heat transfer than saturated steam. It is the latent heat that gives the bang for the buck, and the thin film of condensate on the tubes give a better heat transfer than that for a gas that does not condense. Maybe he has superheat on the...
  3. Joesteam

    Steam Humidifier

    There are two factors here. It is the differential temperature that is the driving force of the heat transfer. With higher pressure steam, the steam temperature is increased and this gives you more heat exchange. Then, the denser higher pressure steam has more chances of condensing on the...
  4. Joesteam

    Steam Humidifier

    Many 'steam to steam' humidifiers work this way, with very little pressure. It is not strictly atmospheric as the steam must pass through nozzles in the delivery tube, but it is close. The delivery tubes themselves are often steam jacketed, so that the initial heat up condensation does not end...
  5. Joesteam

    Steam Humidifier

    For higher pressure steam inlet you can get more steam outlet, however you will use more steam because the latent heat of the high pressure steam is lower, and the sensible heat is higher so you will drain hotter condensate. In general, the lower the pressure the higher the efficiency. Another...
  6. Joesteam

    Steam Humidifier

    I think you are using 5 psig steam in the tubes to make atmospheric steam for your humidifier. the 5psig steam will condense and give you about 960 btu/lb, while the atmospheric steam will need 970 btu/lb to evaporate. the approximately 15 deg F difference in temperature will drive the heat...
  7. Joesteam

    Steam pressure drop and line sizing

    Your answer depends upon what type of reducing valve you have. If it is self contained, you will get a nominal drop with the smaller pipe on the outlet, which also may effect capacity. If you have a pilot operated or pneumatic valve, then if you take your reference pressure AFTER the steam is...
  8. Joesteam

    15 psig steam boiler blowdown heat recovery-good idea??

    The flash steam you will get reducing from 15 psig to 5 psig is minimal, about 2.4% of the liquid at 15 will turn back into steam at 5%. However, if the vessel and system are already there, why not use them even for this small amount?? There are many more BTU's available in the hot water...
  9. Joesteam

    Press Powered Condensate Pump - Steam vs Air

    I am on the side of RMW, the air input into the pumping chamber only has contact with the condensate on the upper surface. At condensate temperatures there will be MINIMAL amount of O2 obsorption into the liquid. Now also it depends upon where the pump is vented. Most are vented to the...
  10. Joesteam

    Covering of thermodynamic steam trap when it rains

    The TD trap has a vapor pressure on top of the disc that keeps it in the closed position. When this vapor condenses or leaks under the seat the pressure drops and the trap opens. The trap will remain open untill all of the condensate drains, more vapor will delvelop on top of the disc, and the...
  11. Joesteam

    Steam "Wetness" in Benchtop Steriliser- Measure?

    You can get around this by installing a steam separator before this device, when properly sized and piped remove 99% of moisture to give the required steam quality. Look at: http://www.lesliecontrols.com/Handbooks/EliminatorHandbook/StmSepProdPg.pdf This is one example, other manufacturers...
  12. Joesteam

    Shell and tube for low delta T with steam

    I have not seen a problem with operating a heat exchanger with 60 psig with your required temperatures. It is the steam control valve that will regulate how much steam is sent to the exchanger based on the outlet temperature of the liquid. Often the control valve modulates down close to the...
  13. Joesteam

    Shell and tube for low delta T with steam

    I have not seen a problem with operating a heat exchanger with 60 psig with your required temperatures. It is the steam control valve that will regulate how much steam is sent to the exchanger based on the outlet temperature of the liquid. Often the control valve modulates down close to the...
  14. Joesteam

    Steam Boiler Pressure Reduction

    Aside from the boiler itself, you must look into the steam distribution system. The specific volume of 15 psig steam is about 3.5 times greater than that of 100 psig steam. So, you really need to calculate the maximum load and see if your steam velocities in the pipe are not outrageous.
  15. Joesteam

    Flash Tank, Sparge/Spray Pipe ??????

    We have seen many of these sparge pipe condensate flash tanks. In every instance the sparge pipe is BELOW the water line. Supposedly if you have a lot of flash or some live steam from failed traps, this will be quenched by the liquid in the tank, and the sparge holes are supposed to prevent...
  16. Joesteam

    Steam heated water heater

    What is your GPM of hot water required? What is your steam pressure?
  17. Joesteam

    Steam heated water heater

    Those injection heaters are good, however you must have 'clean' steam if you use them for domestic water.
  18. Joesteam

    Steam heated water heater

    There are many manufacturers that make prepackaged systems for domestic hot water using steam. Although you can use almost any steam pressure, I prefer to reduce the steam pressure to below the water pressure, then if you get a leak in the tubes, you cannot migrate steam into the hot water...
  19. Joesteam

    hot water generation

    You did not give that much information. I know that Sussman Electric makes hot water generators for building heat. Look At: http://www.sussmanelectricboilers.com/svw1.htm
  20. Joesteam

    system powered steam condensate pump

    Note: not only must the pump be vented but, most of the time depending on your exact piping layout, the condensate entering the pump must be vented. The Vent on the pump body has a very small orifice, designed to vent the pump of the motive force steam. It is often not big enough to vent any...

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