Dutch46 wrote:My view is that Charis and Safehold should try to skip the steam engine era for smaller applications such as vehicle and small watercraft propulsion. For stationary and railroad use, I think steam is fine, at least at the beginning. It seems to me that Charis has met all of the requirements for developing diesel engines. Not efficient ones but that does not really matter at this point. A diesel will run on anything that can be fed into the cylinder at the right moment and is combustible at the heat of compression that is generated in the engine.
Diesel engines require finer tolerance machining than steam engines of similar power and stronger metals. Charis is possibly capable but this would require further work.
Dutch46 wrote:As one raises the pressure of a steam boiler above about 250 lbs, problems of all types rapidly begin to multiply. Worse, they multiply exponentially. Water quality rapidly becomes important and as temperatures and pressures are increased, metallurgy becomes ever more important.
Having worked on 2000psi steam systems, the problems are not insurmountable, the major issues relate to the higher pressures requiring heavier gauge piping and a change from flat gaskets to ring gaskets - the same technology needed for ammonia production. A leak in an occupied area at these pressures is instantly lethal (as opposed to lethal within 20 minutes at 150psi...) as at 2000 psi the steam does not condense for 20ft from the point of escape, leak detection is done with a broom (when the head vanishes you have found the leak).
Dutch46 wrote:Dealing with outages becomes a time consuming business since the fires have to be put out and the boiler and tube sheet cooled to a point where it is possible for humans to work on it. In high pressure boilers, the rate of cooling must be strictly controlled so as not to induce too much stress in the tube metal. The most likely failure point in a boiler is the failure of one or more tubes. One can live with a small leak for quite some time but a large leak means that the boiler must be taken off line as fast as possible because it will run out of water and water is the only coolant in a boiler.
It is usual to swallow leaks until the boiler design pressure cannot be maintained or the water level cannot be maintained at design output, this is usually limited by the boiler feed water pump. For locomotive and road boilers this is usually not a major issue as dumping a boiler for repair is done daily any way, single tube leaks are fixed by driving plugs into the offending tubes on the road.(Leaking tubes are a daily occurrence in large power boilers). Power boilers and marine boilers have higher pressures on up time so larger feed water pumps are filled to cope with leaks. A 800MW boiler that I am intimately familiar with could handle 16 tubes ruptured (open full diameter) simultaneously with no problems (other than higher water consumption).
Dutch46 wrote:Once it incurs a tube leak, the boiler, regardless of whether it is a fire tube boiler or a water tube boiler must be drained at least to below the level of the tube leak. Refilling it may become problematic if the water supply is restrictive as it may well be if the water must be processed before being used in the boiler. Once the pressure comes off, leaks no longer advertise themselves so the answer to that is to fill the boiler completely to the stop valve and then pressurize it. That can be done by running the boiler feed pump until it reaches its maximum pressure and then using a small high pressure hand pump to raise the pressure further. Then one looks for the leak. That is the process in water tube boilers. In fire tube boilers it is simpler, one just looks in the firebox and sees which tube the water is running out of and then plugs it at both ends although I have seen instances where even that seemingly straight forward process becomes a hair pulling event.
As steam locos boiler feed pumps are steam powered, finding leaks can be time consuming with a bucket pump but if it isn't blindingly obvious then the boiler can still be run (but fixing it, if you have the time (i.e. not in an active war zone) is a good idea).
Dutch46 wrote:The usual fix for a water tube boiler tube leak is to cut out the leaking section making sure that an adequate amount of tube is taken on either side of the leaks so as to remove any weaknesses that may have developed in that area and weld a new tube section into place. On Safehold, due to a religiously imposed lack of electrons, they will be reduced to putting plugs on both ends, eventually reducing the efficiency of the boiler substantially. New, custom made replacement tubes will have to be installed to replace plugged tubes during major overhauls.
No, the usual fix is to replace the entire tube, joining a fired tube introduces a point of poor heat transfer, this then overheats and fails again (possibly (probably on high pressure boilers)taking out the tube on either side). With a fire tube boiler joining tubes is impossible anyway, the seals are machined off and a new tube driven through, pushing the old tube out before a new seal is formed at each end. Water tube boilers are harder as the tubes are rarely straight so a full overhaul is required and tubes either side of the ruptured tube are often replaced as well due to restricted access, as the seal riveting has to occur inside the water and mud drums. Joins in tubes also concentrate fouling leading to poor heat transfer and rupture (which is why seamless tubing is required in high pressure boilers).
Dutch46 wrote:So, all in all, this amount of trouble is only worth it for fixed installations or the largest shipboard installations and I classify locomotives as fixed installations where room is not a primary consideration and plenty of spare tubes can be installed during the construction process.
Room on a locomotive is at a premium as the issue is how much boiler can you squeeze into the loading gauge of the line, and weight is limited by the track it runs on,one of the reasons 600psi boilers were fitted to the last generation of steam locomotives.
Dutch46 wrote:All this makes the use of diesels much more beneficial. There are no spare parts for a diesel that cannot be carried on even a small ship. If constructed properly, even a good size diesel can be dismantled and rebuilt in a few days time and it will be as good as new.
So can a steam engine...and requires much less precision than a diesel injector pump overhaul (which requires a specially equipped workshop - and as for carrying spares - even large ships don't carry major engine spares, a broken crank or busted cylinder is a trip ending incident calling for a tug).
Dutch46 wrote:Other problems that are bypassed with diesels are the generation of toxic exhaust smoke, the disposal of toxic ash and the bunkering of coal which in and of itself is not without risk on a rolling, pitching ship. Diesel fuel is liquid and can be used as ballast and replaced with seawater as it is used so as to maintain the stability of the ship. It can easily be pumped and so has none of the handling problems that coal presents.
Anyone breathing the exhaust smoke of diesel deserves what the get - dead...(ask 1 billion Chinese). Ships as a rule don't burn diesel fuel as you would put in your car - what they burn far worse, vacuum bottoms cut with kerosene (the crud from the bottom of the distillation column), the cheapest fuel they can buy - (diesel is lighter than water - vacuum bottoms is heavier and full of crud, sulfur and salts) The fly ash is not a problem - you dump it overboard at sea and use it in concrete (25% is usual) on land. (Liquid fueled steam ships burn straight vacuum bottoms (heated to 400 degrees (by steam heating...) or more recently LPG (particularly in crude oil tankers - the fuel is free). Basically a steam engine will burn anything that you can get in the boiler and set fire to.
Diesels are far more finicky (particularly if you want high power or efficiency), as you need a pre-ignition resistant fuel (high flash point) (unless you use injection rather than a carburetor (another device that will need a new name as it is french). Liquid fueled boilers are much easier. Gas turbines are in the middle ground between the two, and coal fired gas turbines have been built.
Bunkering is messy which is why it is usually done in harbor and why liquid fuels are now preferred. Coal dust firing is however an option and can be pumped round relatively easily - but this became possible just as steam power became a niche market, a couple of coal dust fired loco's were however built. (Lump firing is cleaner but dust firing is enclosed).
Dutch46 wrote:I realize that Safehold, as of this time, has no refining industry so large scale usage is not possible at This time. However, I see no limiting impediments to the small scale experimental development of these types of engines.
To get to diesel you need to do steam first - and do it well, for a number of reasons:
1/ Steam heating is needed for the safe production of diesel via distillation, direct firing is possible but leaks are lethal.
2/ Steam engineering teaches the basis of large scale fired pressure vessel design - which a distillation column is.
3/ You need a driver for the crude oil feed, condensate and vacuum pumps (assuming you are not using steam extractors).
4/ Diesels generate pressures of over 350 psi inside the cylinders - so you need to be able to build a reliable 300 psi steam engine first (Otto cycle engines can run at much lower pressures but require spark ignition).
5/ Diesel engines need to run at much higher speeds than steam engines - bearing design and lubrication needs a lot of work for reliable operation.
A lot of these items explain why it took a century after steam engines became widely available before the first internal combustion engines were built.
In short don't rubbish steam - it works and its a third world compatible and maintainable technology - which most modern diesels are not (as clean rooms are required to overhaul the injectors and injection pumps).