richard orr wrote:All that you have stated I agree with. If; however, one is using the boiler in a stationary capacity ( speaking in terms of theoreticly ideal ) and primarily for the purpose of generating steam, then it seems optimal to place all generating tubes above the heat riser and continue the flow of gasses upward. That configuration would allow for the greatest velocity.It is when using a boiler in a marine application that over all shape has a bearing on design due to the need of acheiving a low center of gravity. In other words, I see no advantage in using the drum unless on is using the furnace for home heating also.
richard orr wrote:First of all please understand, unless you are recirculating the water, the configuration you describe is a once through monotube. A water tube is not defined by diameter of pipe or necessarily volume of water. Also keep in mind that you are talking about generating steam, therefore you have to adress latent heat, I.E. much more heat needed.I agree about the configuration you described as being simplier in construction, but it also means that you will need much more square footage of tubing if you go this rout. Every inch the tubes are from the fire, the more heat will be lost. Also every bit of loss of velocity will reduce the amount of heat transfer to the tubes. One of the critical questions to be asked is how many pounds of steam per hour do you need to generate and at what pressure?
richard orr wrote:How many h.p do you design to have ? What are the particulars of the engine you intend to use?
richard orr wrote:With gasification there is a loss of effeciency in terms of heat delivered. It doesn't mean that it's a bad idea all-together but does raise questions as to why one intends to use it. There could, for example, be a hightened control in terms of being able to isolate the fire from the generating tubes or perhaps a gain in the ability to have a cleaner burn when using wetter fuel.
richard orr wrote:When you talk about gasification do you mean partial or complete combustion?
richard orr wrote:If I am following you correctly, you are ending up with char at the end of the process? If so that char represents unused btu's for a given amount of fuel.
richard orr wrote:O.K. Sounds like a do-able design stratigy. It will even allow for a a certain safety facter as you will be able to more control and isolate the fire. Steady burning solves a lot of the inhearent problems with monotube configuration and larger tube dia. does increase the ratio of water to heat surface thus settling the fluctuations down some. What is the perentages of radiated heat surface to convected heat surface?
richard orr wrote:When running a steam engine at realitively constant demand, water lever (feed rate in a monotube) can be propperly adjusted by a variable stroke feed pump.
I quite understand about your desire for simplicity. that and safety are my highest prioritys. I do believe, though, that you would experience better results by winding a coneacle configuration above the riser tube thus keeping the gasses flowing at the highest possible velocity. Such a configuration would allow for the greatest radiant heating surface to be achieved.
An electric pump does have the advantag of being run independent of weather the steam engine is running. Understand though that when speaking of marine use in a realativly smaller boat that horse power is usually marginal and there is a percentage of power lost by converting mechanicle to electrical. It is also a wetter invironment to opperate on. I personally would only use it for a stand-by mode.
richard orr wrote:What kind of steam valve do you have for your steam engine? If it is a D valve, they don't want very much super heat....perhaps + 50 degrees Also what r.p.m. are you going to run at? If high r.p.m.'s then make sure your check valves are plenty large or you may experience hammering in a monotube.