I have done what you propose by buying a catalog listed unit from Penberthy.
Professional and experienced suppliers are called upon to furnish proven and warranted products. This is not done in conventional engineering circles. It is obvious that someone (you or your supervisors) will have to take the risk and gamble of seeing to it that your design works as per specified needs. study of an ejector and to design a test model for acceler. A fluid cooler and its pump, which use a glycol water loop to reject the condensation energy of. velocity annular primary air jet to the central ,Rrticle. What you are proposing is not the conventional case since you yourself admit you know little or nothing of designing such a unit. influence of nozzle design on jet ejector performance.
With proven designs available, why would you feel pressed to design, test, modify, and install your own personal design? Are you limited in being able to buy an existing, proven & warranted design? This is understandable, since a lot of the technology is locked up by the existing manufacturers who have spent a lot of time and money in developing their designs.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.I've only heard of two instances where an engineer took to designing and building his own ejector. Steam is a very good motive fluid, so you'll be able to bump all of the ratios a bit in a good direction. None of these "rules of 2" are exact, but before you waste a bunch of time chasing a marginal project it is worthwhile to apply them to see if you're in the ballpark. Make sure that flow and pressure are available under flowing conditions. Total flow is sum of feed and supply required. Your steam demand (in mass flow rate terms) will be about twice your suction requirements (i.e., if you need to move 2,000 lbm/hr of suction gas you'll have to supply 4,000 lbm/hr of steam). The eductor design application below will give the required inlet pressure and water flow needed with each size eductor at various discharge pressures. For practical purposes, you'll want to look at about 2 compression ratios (i.e., for the 20 psia exhaust you'll only be able to pull the suction down to about 10 psia). and an additional one third is rejected to ambient at the cooling water system. if you're exhausting into 20 psia, you'll need something over 40 psia steam). so the jet-ejector performance in off-design operating conditions can be. For scoping evaluation, you'll need something like twice the steam pressure as your exhaust pressure (i.e. It sounds like you're in the market for an "ejector".
If you are trying to compress a gas then you don't want to use an eductor (the effeciencies are too low, I've done it but it requires a lot of power fluid). The reason for the lecture is that if you a trying to pump liquid you don't want to use and ejector (velocities get pretty high). Steam can be used as the motive fluid in either case. The throat has a very short entry transition and a straight section followed by a divergent section.Īn ejector is intended to move high gas-cut fluids and has a convergent section for an entry to the straight throat which is again followed by a divergent section. They're all in the same family, but they're each a different beast.Īn eductor is a device intended to move high liquid-cut fluids. RE: Eductor calculations codeeng (Petroleum) 17 May 05 10:34Įductors, Ejectors, Jet Pumps, hose-end sprayers, and sand blasters are all in the family of equipment called "thermocompresors". The two then exit the eductor at an intermediate pressure.Īlso, any good sites that thoroughly explain steam usage in refineries? I am looking for something that starts with the basics of steam. This in turn sucks the stack gas into the eductor. were used, the shift in these curves would be to the left. The pressure of the motive stream is dropped, to increase its velocity. 2, all of the curves representing the performance of ejectors that require water would be shifted to the right, indicat-ing an increase in capacity for these designs. This flow will serve as a "fast loop" that every so often an analyzer will pull a "slip stream" from to test.Īny suggestions as to how to formulate a relation of motive stream to outlet pressure? The eductor used for gases is basically a converging/diverging nozzle from what I understand. The outlet of the eductor will have a stack gas/steam mixture that will then be returned to the stack. We are passing the steam at some pressure (this is what is to be determined) through the eductor to induce the flow of a stack gas, which is at or near atmospheric pressure (may actually be a slight vacuum).
The question is what pressure can we regulate this steam to in order to still maintain the flow. We have up to a 150# steam supply as the motive stream. I am a new engineer and am looking for pointers on calculating the flowrate needed to move a gas.