Water Injector: Steam Exhaust?

Hello,

Quick question involving feed water injectors; is steam still exhausted from the system, or does it condense within the injector?

All the Best,
-Parker

If it condensed within the injector, you have no work. Since injection is a natural refrigeration process, you sacrifice expander output with compression that generates heat. Nutshell response.

I was assuming you were injecting the the heat exchanger water directly into the expander, hence the response. You could be talking about other things as well, please explain.



Edited 1 time(s). Last edit at 07/04/2010 09:40PM by kdc2.

There are books on steam injectors and what is interesting is that they do not work if the water is too hot. There are many people who know all about these things and I am not one of them, which does not stop me from having an opinion. The steam stays in the system and is condensed. The pressure increase, which is needed to pump water into a pressure vessel, comes from the kinetic energy in the water. The problem is that one is using steam at exactly the same pressure as the water will be when injected into the boiler. I just looked through my library and a good book is "Elements of Heat-Power Engineering" by Hirshfeld and Barnard, both from Cornell printed in 1912. Here is the quote from page 712: under Steam Injectors, used for delivering feed water to boilers: "Briefly it operates as follows: Steam, admitted through valve V, acquires high velocity in passing through the nozzle, is condensed by the water in the combining tuibe and drives the water through the delivery tube and check valve into the pipe leading to the boiler. thus, the flow through the nozzle is similar to that in the ordinary case, and the kinetic energy of the jet is used for injecting the water into the boiler against the pressure existing there". This fine book has a cross section drawing of the injector nozzle. This is not an efficient system, but because it does not involve moving parts it is more reliable than a mechanical pump. It was often used on locomotives. As stated before there are people out there who actually understand these things. Tom Kimmel

As Tom has stated the feed water needs to be on the cool side. Normal feed Water should be 170 F to be free of most of the oxygen. Using an injector the feed water needs to be around normal air temperature. All the steam condenses between the injector and the boiler. I have used them on both my Steamboats for the last 45 years. Never saw one that would work above 300 PSI. My 35 footer ran at 275 psi and as back up to the two feed pumps had a ½ Penberthy. I also use ejectors as bilge pumps, a little different configuration but it only discharges water.

July 16, 2010
I just located the relevant book. It is a Lindsay Publications reprint of an 1894 book by Strickland L. Kneiass "Practice and Theory of the Injector". The book is 129 pages long and has drawings and illustrations and will tell you more than you would ever want to know about steam injectors. There is an whole another story about efficiencies. It is my impression that injectors are the least efficient followed by duplex water pumps which are next least because of the 100% cutoff that is needed. One of those British guys, I think it was the Morris Mini designer whose name I cannot spell because it is Greek, had a design for a free piston steam engine running a hydraulic cylinder as a pump and he did a sliding cam that changed the torque needed as the steam expanded and pressure dropped in the steam cylinder. Something of this nature would be much more efficient than a duplex water pump. It may be that someone clever can come up with a mechanical linkage that would accomplish the same thing. Tom Kimmel

tkimmel@locallink.net Wrote:
-------------------------------------------------------
> July 16, 2010
> I just located the relevant book. It is a Lindsay
> Publications reprint of an 1894 book by Strickland
> L. Kneiass "Practice and Theory of the Injector".
> The book is 129 pages long and has drawings and
> illustrations and will tell you more than you
> would ever want to know about steam injectors.
> There is an whole another story about
> efficiencies. It is my impression that injectors
> are the least efficient followed by duplex water
> pumps which are next least because of the 100%
> cutoff that is needed. One of those British guys,
> I think it was the Morris Mini designer whose name
> I cannot spell because it is Greek, had a design
> for a free piston steam engine running a hydraulic
> cylinder as a pump and he did a sliding cam that
> changed the torque needed as the steam expanded
> and pressure dropped in the steam cylinder.
> Something of this nature would be much more
> efficient than a duplex water pump. It may be
> that someone clever can come up with a mechanical
> linkage that would accomplish the same thing. Tom
> Kimmel

It was actually reading the description of that book which resulted in my question!

Thanks for your responses, everyone. I had a good feeling that it was a condensing process, but wasn't entirely sure.

Hello Tom,

Is there formula and explanations on figuring efficiencies of ejectors in that book?

I'm interested in using ejectors to drive water through a radiator. Also volume or mass relations between the water and steam.

Andy

Quote
Andy P.
I'm interested in using ejectors to drive water through a radiator.

found this link, [en.wikipedia.org] I know its a WIKI.... But its the reference to the hardware that caught my attention, looks do-able Andy, seems to me there's been a simular mention with regards to Ken's water level control in his boiler. : )

These type of pumps are used for other applications aswell. They almost seem commonplace.

Jeremy

-edit- just as an aside, a "Flash Steam Injector" designed for admission into a "Flash Steam Engine" is of a completly different configuration and has a simple geometry of only one "divergent nozzle".
-



Edited 1 time(s). Last edit at 07/17/2010 03:12PM by Jeremy Holmes.

Thanks Jeremy

I have three ideas using ejectors. The most basic is as a simple condenser where ejector is use to force water through a radiator. The purculator condenser. The second idea is a Tesla exhaust turbine. From what I can find on Tesla turbines. Thay have a good efficiency using a liquid. But not when using a gas. And have other problems runing high temperature steam. This idea simple would use exhaust steam to power a water Tesla turbine. Thermal efficience wouldn't be an issue as the heat would be recovered in the transfer to the feed water. The work from the turbine could power auxiliaries.

If an ejector could get good thermal efficiency then the Tesla turbine of this type could be a viable steam engine.



Edited 1 time(s). Last edit at 07/18/2010 09:42AM by steamerandy.

Hi Andy,

Regarding the Tesla Turbine, I think you are correct with regards to surface tension related to the turbines performance, seems to me they pump water the best.

These guys (there from Russia) teslatech. They sent me an email a while back inviting me to check out there stuff that they have published on there website. To be honest, of all the tesla turbines ive seen, there stuff looks the best. The whole site is in Russian so I cant read very much of it.

[www.teslatech.com.ua] opens to photos
[teslatech.com.ua] page of links to photos

Since you mentioned the tesla turbine i figured this would be of interest to you.

Jeremy

-edit- fixed 2nd link-



Edited 1 time(s). Last edit at 07/18/2010 11:36AM by Jeremy Holmes.

What is cool, is that if you copy the url, do a google search on it, then hit the blue translate page and your good to go.