Monday, January 05, 2009


I'm still working on the inversion project for the knowledge base. So far, I've followed this down through science, physics, mechanics, and particle mechanics to improve the content and links of this section; I had last worked on it last February.

As a bit of personal background, I was growing up in the 1960s when the environment was becoming an important topic, and I developed something of an interest in renewable resources that can be done on a small scale, sustainable basis. I'm also interested in innovation and doing things as inexpensively as possible.
So, the wooded hillside that I've mentioned that I live next to (downhill from me, fortunately) is economically entirely unproductive, or it would be if anything were done on a large scale. It's too small for conventional forestry or logging, which would leave nothing but an ugly, barren hillside. It's too steep for agriculture, or building. There isn't much that can be done in the way of conventional forestry or logging, or agriculture; especially since I don't own the area and don't have the rights, or know-how, or equipment. What it does have is brush (including the multiflora rose I mentioned last post), fallen trees and tree branches, and trash (I've seen a vacuum cleaner, a lawnmower, and various tires) . If I can figure out what can be usefully done with this, it should be extensible I've seen a lot of property more or like this around town.
On a small scale, I can do some unobtrusive experiments. I mentioned the bush I've pretty much cut down, but it has many neighbors just like it. I talked a bit about it about that species to a friend who is a professor of agriculture at WVU and runs a farm in his spare time, and confirms my impression of it as a pestiferous species. What do I do with it once I prune it down to the roots? It would seem to be only fit for burning.
The question is, burning how and where? When I was playing around with information from New Mexico, and I came across creosote bushes (a species I'm familiar with from Arizona where I was raised), I was wondering what can be done with them. I was thinking about aromatic oils, and whether they could be extracted, and I came across mention of distillation. Distillation? of wood? so I looked at that a little bit, and moved on, in the process noting that it was once a chief source of methanol, wood alcohol. Well, methanol is one of the simpler organic compounds, so I've been running across it in my studies of organic chemistry.
So, I was doing some study of small woodburning stoves, wood combustion and pyrolysis, and distillation, all of which are more or less related in theory, and after sleeping on this for a few nights, came up with an experiment I want to try.
The ordinary burning of wood doesn't directly burn the wood at first. What it does is force it to give off combustible gases, which in turn heat the wood further, driving off more gases, until at length nothing is left but ash. The temperature depends on the composition of the wood in question, and on the rate of mixture with the oxygen in the air, which would be rapidly depleted
if there were not some kind of air flow. This is usually supplied by a chimney: The burned gases get hot, less dense, rise, and create an airflow. The difficulty is that this combustion is incomplete. The exhaust gas (smoke) contains not only air, somewhat depleted in oxygen, and the end products of water and carbon dioxide, but it also contains carbon monoxide, volatile organic compounds, ranging from the simplest to the heaviest; many of which are somewhat toxic and irritating and unburned particles of fuel. More efficient combustion occurs when there is a better mix of air and fuel, and when combustion takes place at higher temperatures.
Much a similar process occurs when wood is simply heated in the absence of oxygen; it gives off combustible gases, some organic liquids, and leaves charcoal behind. Producer gas, wood alcohol, and charcoal have been produced for centuries. Charcoal is interesting, because it's a renewable resource, and something of a substitute for coal. However, producing it is an old technology and rather wasteful of wood.
So, in the interest of efficiency, I've decided to experiment with a device in two parts: one a stove, where the primary interest is in combustion, efficient burning, and heat, which drives the other part, the oxygen-free destructive distillation of wood. This should yield combustible gases, which in the absence of good gas handling material, I can feed back into the stove. However, before burning these gases, I want to extract some of the volatile organic compounds, at least those which are liquid at normal atmospheric temperatures, and range from tars to alcohols. The solid should be charcoal, which can in theory be used to experiment with glassworking and metalworking.
However, all this is theoretical, and to make an idea like this work, I need to do some experiments and observations. I've asked another friend if he would be willing to help me make a hobo stove, as the first stage of this experiment, so I can get started.

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