I don't want to completely derail the thread, but you could take that adage to get rid of a lot of economizer/condensing steam clap trap.
An injector weighs a less then a pound, and is tiny, and it preheats the water itself. I have read that it is nearly 100% thermo dynamically efficiency in what it's doing. For non condensing applications it basically surpassed steam pumps (as much as I like to watch a duplex).
I don't have an injector on Otter. I was always under the impression that one needed to minimize the pressure drop between the injector and the boiler; this makes an injector difficult to use w/ a feed water heater. Did I not understand this correctly?
Heating the water as hot as possible before putting it into the boiler is essential, I think, and between a initial feedwater heater and then a pass through the economizer coils we can get pretty close. I think a mechanical pump is essential for routine boiler feed, esp. on a condensing boat.
I too am using a hypro, chain driven to the prop shaft, the pump is quiet but you do hear a little chain noise even though it's mounted under the floor board. It is bolted to the cabin wall and I think that amplifies it.. I've also got an injector (1/2in Penberthy) which CAN fill the boiler in a hurry. I also had problems starting it until I moved it's feed to a dedicated line to the water tank, in my case the injector is below the level of the tank. If the water is warm OR if there are any vacuum leaks in the input the injector won't work. And because of packaging my injector is mounted to a 90 degree bend and then a shutoff valve, not a good design but it still works well, good luck rp
While an injector is considered "100% Efficient" because all the heat in the driving steam enters the feedwater, it has some thermal problems, mainly its need for cold suction water. Beyond that, they seem to give reliability problems more than simple reciprocating pumps. Injectors must use "live steam" to heat feedwater, where other means of getting the feedwater heated need virtually no "live steam".
For our steam plants, the power required to run a mechanical plunger or piston feed pump is only a few percent of engine output, about 3% at most. This is so small that it really needs no consideration. The positive displacement pump can pump warm water, the injector cannot.
Feedwater heating is easy on our small steam plants, an exhaust steam heater can easily bring feedwater within about 20F (10C) of exhaust steam temperature, and with the exchanger mounted downstream of the piston pump, an efficient arrangement. Not much benefit available here with an injector, where the discharge feedwater is already well heated by the injector.
The economizer, taking heat from the flue gas that has already passed thru the boiler is also a good way to increase economy, as well as bolstering steam generation. Economizers can easily bring the feedwater temperature to 300F or as much as 350F (150C - 175C) before it enters the boiler proper. Steaming within the economizers is generally avoided in large plant practice, due to water-hammer concerns, but many small economizers can steam on occasion, and banging pipes are not often a problem on our small plants.
DetroiTug wrote:Cyberbadger, you need to lighten up and be respectful of others with views that differ from your own, we keep a civil discourse here and try to be polite with one another.
On page two of this thread I wrote:
cyberbadger wrote:Still 2 sources that work and are easy to use are really needed and diversity is good.
I have no problem with hypros/other engine driven pumps. I feel this forum is currently frequented by hypro launch users who appear from my perspective to believe injectors that have no place in a steam launch as a good feedwater solution when underway.
I respectfully disagree with that. I think there are many water feed sources that solve the solution for a launch. And I'm tired of getting shot down everytime by the seeming current majority everytime I mention the injector opinion - it is a valid solution.
Remember that many of us operate in salt water. or water that's otherwise unsuitable for boiler feed. I've run w/o condensing in such situations when Otter was new; I had a operating time of about an hour before I needed to take on more feed water.
If one does have a condenser, the natural method to control hotwell level is a float-operated bypass, which does have the happy side effect of also regulating boiler level so long as the overall losses of water aren't too severe.
Water tube boiler react much more quickly to changes in feed, since they have less volume. Intermittent feeding of water to the boiler tends to lead to swings in water level, and makes less effective use of feedwater heaters and economizers.
In such configurations, injectors are not a good choice as the primary means to put water in the boiler
For firetube boilers running in fresh water, I'm sure they work just fine.
barts wrote:For firetube boilers running in fresh water, I'm sure they work just fine.
Which is exactly what I'm building the Nyitra for. Puffer(non condensing), firetube boiler, fresh water.
Being in the middle-ish of the USA in Ohio I really have no plans to take Nyitra or a future launch to operate on salt water. Also I've permanently fallen in love with firetube boilers, I like VFTs. Maybe someday I'll get a scotch marine. I don't have any interest in water tube boilers for my own kit.
I understand that you will be steaming in fresh water but it is still filthy stuff compared to what is in circulation in a condensing system. And usually loaded with dissolved oxygen. Not great for your boiler.
I have worked on a large non-condensing power plant (a full sized locomotive) and the crud that builds up in the boiler is ugly to say the least. And this was in an area with very soft water.
My personal objection to an injector is that it is a batch process. You have to watch the glass and top off periodically. One more danged thing to deal with when I could be enjoying boating. I'll take a stable steady state system any day.
I'm not stuck on the Hypro but it is less hassle than some sort of home made reciprocating pump with all the teething and optimizing that comes with that. I want my power plant to just run, not demand my attention all the time.
If you think you are too small to make a difference, try sleeping with a mosquito.
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