# Some questions about Steam Injector principle

## Main Question or Discussion Point

http://www.mekanizmalar.com/how-steam-injectors-work.html
In the link above, the basics of steam injector is given. Steam Injector's don't have any moving parts and doesn't consume any energy by themselves. Still, it can be able to pressurise water and inject that to a high pressure Boiler by using the steam from that same Boiler. By going through the description, anybody with some knowledge of physics can understand that the Latent Heat of Vaporisation of the steam will be used to increase pressure of the injected water.
Now, I just want to know if the working and suction fluids are reversed i.e. if water is used as the suction fluid and steam as the fluid to be sucked and pressurised, can injectors be useful for that purpose? As per some information gathered from steam injector manufacturers, it will take around 1 kg steam to suck 11 kg of water. Simple rule of thumb says that it will take around 11 kg of water flow at the same speed to suck 1 kg of steam. But, question is whether any kind of formula is available for that purpose and can we calculate how much water with level of speed is necessary to raise a definite amount of steam from Pressure A to Pressure B.
Want to hear from others here.

## Answers and Replies

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Nidum
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Thank you for your reply. But, I want to know how much water would be necessary to absorb the heat of a specific amount of steam.

Nidum
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(1)
As per some information gathered from steam injector manufacturers, it will take around 1 kg steam to suck 11 kg of water. Simple rule of thumb says that it will take around 11 kg of water flow at the same speed to suck 1 kg of steam. But, question is whether any kind of formula is available for that purpose and can we calculate how much water with level of speed is necessary to raise a definite amount of steam from Pressure A to Pressure B.
This is not a realistic proposition so no meaningful calculations are possible .

(2)
Thank you for your reply. But, I want to know how much water would be necessary to absorb the heat of a specific amount of steam.
Easy enough to calculate how much water is needed to condense a certain amount of steam but is that really what you are asking about ?

Easy enough to calculate how much water is needed to condense a certain amount of steam but is that really what you are asking about ?
I want to know how much water flow is necessary to "compress" steam, not "condense" steam.

Nidum
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Draw me a sketch of a device that could actually do what you are proposing .

Already given in the link with which this thread is started. Just interchange steam and water.

Nidum
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See if you can figure out for yourself why that will not work .

There are applications available that can compress gas with water/liquid by this method. Then why not steam?

russ_watters
Mentor
There are applications available that can compress gas with water/liquid by this method.
Can you provide an example?

The processes you linked and proposed in the original post are not equal and opposite: as you said, the latent heat of vaporization of the steam is consumed in the process in the link.

Also, since you are proposing a different process (different fluids) from what the link you provided shows, the link does not fulfill @Nidum 's request. You need to put more serious effort into these thoughts you are trying to evaluate. You're taking ideas that sound vaguely similar if you describe them vageuly enough and treating them as if they are the same. They aren't. Draw a sketch and label the states and processes.

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Just google with "liquid jet compressor" and you can find a lot by yourself. And what I want to mean is that what I am proposing is almost same as the drawing in the link, but the place of steam and water is interchanged. In short, the water has become the motive fluid and steam become the suction fluid.

Mech_Engineer
Science Advisor
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We're not doing your research for you. You'll need to provide a diagram of what you're proposing to effectively communicate these ideas.

It's already available in market and isn't a matter of research now. Liquid jet ejectors can be bought.