paulhorth

No. A compound steam engine, or a triple or quadruple expansion steam engine, instead of expanding the steam from P1 to P2 in one cylinder, distriibutes the expansion across two, three or four cylinders. The total expansion is the same as if a single cylinder was used, but the energy is extracted more efficiently, leading to more work from the same steam flow. The reason for the better efficiency is to do with the temperature difference between inlet and exhaust, if this is too large there can be condensation in the cylinder when the inlet steam enters the previously exhausted volume, leading to waste of steam, and there are other practical factors such as valve timing and mechanical design. If you try to expand steam from say 50 bar to 1 bar in one cylinder, the admission valve would have to close after 2% of the stroke, which is difficult. The cylinder would have to be both large enough for the exhaust flow at 1 bar, and also strong enough for the inlet pressure of 50 bar. This is not an optimum mechanical design. More work can be extracted from steam at higher pressure, and expansion from higher pressure is most efficiently done in several stages (as it is in a turbine). Paul The engine designer would aim to get equal power from each cylinder, not (as you say) always more from the HP cylinder. Sometimes in large engines the steam was reheated between one cylinder and the next, using waste heat, and improving efficiency.

Satheeshsg, Your equations are not displayed in the post. Nevertheless, though I am not a calculus expert, i think the manipulation below is correct: for any x, dx/da =dx/db. db/da so, whatever x is, dx/d (rho) = dx/dv . dv/d(rho) I think this is true for partial derivatives also then since v = 1/ (rho), dv/d (rho) = -1/(rho)^2 so dx/d(rho) = - (dx/dv)/(rho)^2 Paul.

Coming back to the question of absorption of H2S and SO2. Although off topic for CO2 sequestration, I am interested because, in the oil and gas industry, amine solvents are used largely for removal of H2S rather than CO2, so I thought that your solid amine compounds could also have this function. It's true that in flue gas there isn't much H2S, all the sulphur in the fuel should be SO2, and this only in coal fired systems. However, the SO2 might take up capacity in your adsorbent and would need to be effectively removed on regeneration. There is a lot of H2S produced worldwide with oil and gas, and it all has to be removed. It is generally oxidised catalytically to sulphur. Because the supply of sulphur far outstrips the demand, the sulphur accumulates in huge cast slabs in certain parts of the world. The sulphur blocks in the Tengiz oilfield in Kazakhstan can be seen from space (so I'm told...). Any new process for H2S removal offering advantages over amine solvents would find a great deal of interest. Paul

I'm relieved to hear that. The first thing to decide when considering making a steam boiler is the PRESSURE you want to design it for. This will determine a lot of important features, not least, the cost. Then determine how much steam you want (in kg/h), look up the latent heat at your chosen pressure, that gives you the heat input rate required into the steam. Then decide on your fuel or means of heating. With an electric boiler (like a kettle in your kitchen) the heat to steam translates directly into kW of power input. With a coal-fired boiler like on my model, it's not so simple because of efficiencies. Quite a lot of heat from the coal goes out the chimney with the flue gas, and not into the water. Similarly with a gas-fired boiler. Then you need to consider how to keep the boiler filled. This is an essential safety feature in a fired boiler. You will need a pump and a water supply. You will need a level gauge to see the water level, and a relief valve (safety valve) to protect against overpressure. You will need to consider how the pressure is to be controlled. With electricity it's on-off. With gas it's turning the flame up and down like on your cooker. With coal, well there is no proper control at all, but you won't be doing it that way. With meths firing like on a Mamod steam toy, there is no real control either. What's it for? Paul

I'm not a chemist, but I am a chemical engineer in the oil & gas industry, fairly familiar with amine solvent processes for removing CO2 and H2S from hydrocarbon gases (not from flue gas). So my comments start from ignorance of this interesting field. The basic problem with recovering CO2 from flue gas is the low pressure and the low concentration, so the driving forces are poor. Better to recover CO2 at higher pressure from some kind of pressurised combustion process. I would mention a couple of engineering problems with a solid absorbent for flue gas: (1) Flue gas is dirty, full of all kinds of rogue components like ash and partly combusted stuff, which would foul the adsorbent (2) How do you deliver the heat for regeneration? With a conventional amine solvent you boil it, with a solid bed you would need to pass heated clean gas through it. Generating this gas requires a whole additional system. More general points: Converting the CO2 to trees changes the question to "what do we do with all this wood?" Answer: -burn it, and recycle to more trees? OK, but trees need two scarce resources, namely land and time. Further question: Can this metallic compound be modified to adsorb SO2? or even H2S? I'll follow with interest Paul

That's because the exact ancestors are not known. If you find a fossil, you can say that, based on careful comparisons, it shows a relationship with this existing animal or with that other fossil, to a greater or lesser degree than with others.These relationships can support placing the fossil in this or that branch of a tree, but you can never say, even in principle, that fossil X represents the direct ancestor of fossil Y or living species Z. Even DNA can't show that. My DNA might have quite a lot in common with that of Julius Caesar (if we had a specimen) , but that does not amount to proof that he was my ancestor (or was not). All we can really say about common ancestors is that they probably had a list of characteristics that are shared by their descendants, Paul

Try this link: http://tolweb.org/Catarrhini/16293 This website allows you to move up and down the tree of life to explore the relationship between species. The common ancestors you mention would be at the branch points in the tree - but of course not all f them have been found. Paul

NO NO - STOP!!!! I hope you realise that what you are proposing to do is highly dangerous and also illegal. If you build a steam boiler without knowing how to design and fabricate, you could easily kill yourself and anyone in the vicinity. Any vessel built to withstand internal pressure MUST be properly designed and constructed, and inspected and tested by a competent person. That's the LAW (at least in the EU)as well as obvious engineering sense. Above a certain (small) size, in the EU you must comply with the Pressure Equipment Regulations (google it). The tests include a hydraulic pressure test and a steam test. It's your responsibility to check the law elsewhere - but the engineering comments above, and following, are universally valid. Welding stainless steel is difficult and requires profssional training. The boiler must have at the minimum a safety valve which can be demonstrated to release as much steam as can be raised, without the pressure rising more than 10% above the set pressure. I write having constructed a model steam traction engine, including the boiler, which was made in copper, which is fired by coal and runs at 90 psig. This boiler is tested every year at my club and a certificate issued. Model steam engines of this kind are exempted from the Pressure Equipment Regulations if they are below the size threshold and because of the inspection and testing procedures defined and carried out by the clubs. I am also a professional engineer and spend a lot of my time designing protection systems for pressure vessels. Making a pressure vessel is not a game. Paul