Although we can't seem to find the specific report, or reports, in the West Virginia Coal Association Research and Development Archives, we long ago, on more than one occasion we believe, made reference to, and documented, the fact that Acetylene gas - - which should be familiar to every old country boy who ever had to, before the days of simple and cheap electric arc welders, use a torch to braze on a sheet metal patch over a rust hole on his work truck or slice through a padlock he lost the key to - - is a hydrocarbon which has traditionally, whether it was obvious or not, been made, indirectly, from Coal.
Coal mining history buffs will be familiar with the old-time, open-flame cap lamps that were used before rechargeable batteries became good enough to power an electric light for a full shift, or a little more, of work. Those cap lamps were fueled by Acetylene, which was generated in a reservoir attached to the lamp's reflector, where Water was poured into and mixed with little lumps of a chemical called Calcium Carbide.
Water reacts with Calcium Carbide, CaC2, to produce Acetylene, C2H2.
The basics are explained in:
Acetylene - Wikipedia, the free encyclopedia; "Until the 1950's, when oil supplanted coal as the chief source of carbon, acetylene (and the aromatic fraction from coal tar) was the main source of organic chemicals in the chemical industry. It was prepared by the hydrolysis of calcium carbide, a reaction discovered ... in 1862 and still familiar to students: CaC2 + 2H2O = Ca(OH)2 + C2H2."As an aside, and we mention it since we will be bringing it up again in a future report, if you read the full Wikipedia article, you'll discover that some Acetylene is made nowadays by starting with Methane as the raw material. That's okay, since, as seen most recently in:
West Virginia Coal Association | California Bugs Convert More CO2 into Methane | Research & Development; concerning: "United States Patent 7,807,427 - Methods and Compositions for Production of Methane Gas; 2010; Assignee: The Regents of the University of California; Abstract: The present invention provides methods and compositions for sustained methane production from atmospheric CO2 and solar energy from the sun";
we can now make all of the Methane we might want from stuff that's free, or even better than free.
However, Acetylene can still be made, on both small and large industrial scales, from Calcium Carbide; and, with the increasing price of petroleum and natural gas, as the Wikipedia notes, it again increasingly is, even as one of our subjects herein would seem to attest.
There are, in fact, a lot of uses for Acetylene above and beyond its employment as a fuel for torches and lamps; and, some of those uses are very, very intriguing, as we will see in some reports soon to follow.
And, those future reports motivate us to demonstrate herein the fact, that, we have known for a long time how to make Calcium Carbide, and, thus, Acetylene, out of Coal; and, we continue to get better at it.
First, as excerpted from the initial link in this dispatch, we submit:
"United States Patent 1,137,567 - Manufacture of Calcium Carbid
Date: April, 1915
Inventor: Frederick Becket, NY
Assignee: Union Carbide Company, NY
This invention relates to the manufacture of calcium carbid, and particularly to an improved process of preparing the charge for reduction in the electric furnace.
(Now, if the electricity is generated from Coal, then Coal can be seen to be consumed in two ways for the manufacture of Calcium Carbide, and, thus, Acetylene. But, we believe we should start thinking in terms of conserving our Coal as a precious resource, so maybe some alternatives, like a dedicated hydro or wind generation facility would be preferable. However, later techniques, as we will see further on in this report, make that unnecessary.)
An example of the invention is as follows: Calcined limestone is mixed directly with a definite proportion of a suitable bituminous coal rich in volatile matter, and the mixture is subjected to a coking operation, preferably in coke ovens ... .
In practice of the process, I have successfully used a coal from the Youghiogheny district in Pennsylvania."
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We'll close there for the sake of brevity. The mixed limestone and Coal are subsequently subjected to coking, to drive off "volatiles", and the resulting "briquettes" are then treated in an electric-arc furnace to form the "calcium carbid".
And, to give due credit, the above is actually a variation of the original Coal-based Calcium Carbide manufacturing process, dating from the late 1800's, which was invented in Canada and is disclosed in two Canadian patents that aren't, insofar as we have been able to determine, web-accessible and don't have United States patent counterparts.
Those Canadian patents gave rise to the initial Calcium Carbide and Acetylene manufacturing industrial enterprises in the United States, which were centered in the state of New York.
The basic process remains the same, but gets improved upon from time to time, as seen in:
"United States Patent: 4391786 - Production of Calcium Carbide
Date: July, 1983
Inventors: Hans-Joachim Kersting, et. al., Germany
Assignee: Hoechst AG, Germany
Abstract: The invention relates to a process for making calcium carbide by reacting an excess of coke with quicklime in the presence of oxygen in an oxygen-thermal furnace. To this end, the invention provides for precrushed coal to be used as starting material for coke and precrushed lime hydrate (Ca(OH)2) or precrushed limestone (CaCO3) to be used as a starting material for quicklime. The precrushed materials are mixed and the resulting mixture is introduced into a drying zone and freed therein at 80 to 120 C from adhering water. Next, the warm mixture coming from the drying zone, and air, are introduced into a calcining apparatus in which the coal constituent is coked and the lime constituent is simultaneously dehydrated or decarbonized, at temperatures of 900 to 1400 C. The thermally-pretreated mixture of starting materials with an inherent temperature of 900 to 1000 C is then directly introduced into the oxygen-thermal furnace and reacted with oxygen to calcium carbide."
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The full Disclosure of "US Patent 4,391,786" goes on to explain how, rather than electric arc heat, as in "United States Patent 1,137,567", an excess of Coal is blended with the Limestone prior to the initial drying and subsequent coking. The excess Carbon is combusted in the "oxygen-thermal furnace", thus helping to provide the heat necessary to form the Calcium Carbide from the remaining Coal/Coke and calcined Limestone.
So effective is combining Coal with Limestone, to make Calcium Carbide for Acetylene production, that folks all around the world keep working to improve the process, as can be seen most recently in:
"United States Patent Application: 0110123428 - Method and System for Producing Calcium Carbide
Date: May, 2011
Inventors: Zhenyu Liu, et. al., China
Abstract: A method and a system for producing calcium carbide, the method including mixing powdery carbon-containing raw material with powdery calcium-containing raw material, and directly heating the mixture by combusting a part of carbon-containing raw material in an oxygen-containing atmosphere to produce calcium carbide. The carbon-containing raw material can be coal (and) the calcium-containing raw material can be calcium carbonate, calcium oxide, calcium hydroxide or carbide slag.
(Limestone would qualify nicely as "calcium carbonate". And, we have more than plenty.)
The system includes a raw material preheating unit, such as a fluidized bed or an entrained flow bed, and a reaction unit such as an entrained flow bed.
By combustion of the by-product CO produced during the production of calcium carbide or auxiliary fuel in the air to preheat the raw materials to 500-1500 C, the carbon consumption and the oxygen consumption for the calcium carbide production can be reduced, and thus process energy consumption is further reduced.(In other words, the waste Carbon Monoxide, the effluent "CO", which is flammable, can be captured and burned to provide some or all of the needed heat energy, an improvement over the above "US Patent 4,391,786", which just burns, and thus consumes, more Coal. Either process, though, reduces or eliminates the need for the "electric furnace" of "United States Patent 1,137,567".)
Background and Field: The present invention relates to a method and a system for producing acetylene stones (i.e., calcium carbide (CaC)), and more specially, to a method and a system for producing calcium carbide by providing heat directly through partial combustion of a powdery carbon-containing raw material and a powdery calcium-containing raw material in an oxygen-containing atmosphere.
Acetylene stone, i.e. calcium carbide, is one of the basic materials in the organic synthetic chemistry industry. A series of organic compounds can be synthesized by using the calcium carbide as raw material, to provide source materials for fields such as industry, agriculture, and medicine, and calcium carbide is honored as the mother of organic synthesis before the middle of last century. Hydrolysis of calcium carbide results in acetylene and calcium hydroxide ...
(The byproduct "calcium hydroxide", "Ca(OH)2" as formulated above by the Wikipedia, has a number of uses, by the way. It isn't just "waste" that must somehow be neutralized and disposed of. If nothing else, it can be tossed into a cement kiln and transformed into Calcium Oxide, CaO, the basis, as compounded with various silicates, of Portland Cement.)
At present, acetylene is mainly used for producing vinyl chloride based, vinyl acetate based and acrylic acid based products and the like. For example about 70% of PVC (polyvinyl chloride) production in China is originated from carbide acetylene. In recent years, rising oil price promoted industrial development of calcium carbide, and calcium carbide production in China increased from 4.25 million tons in 2002 to 11.77 million tons in 2006.
(Note in the above that China is already using the Acetylene it makes from, basically, Coal and Limestone, for the synthesis of, among other things, certain types of plastic, in a direct replacement of what would otherwise be petroleum-based petrochemical raw materials.)
The present invention aims to overcome the disadvantages such as "high investment, high energy consumption, and heavy pollution" presented in conventional acetylene stone production processes, and to provide an acetylene stone production method and system with simple process, low energy consumption, wide sources of raw materials, continuous production, large production capacity and low cost.
According to one aspect of the present invention, a method for producing acetylene stone based on oxygen heating process is provided, which includes the following steps:
(1) preparing a powdery carbon-containing raw material with a particle size of smaller than 1 mm and a powdery calcium-containing raw material with a particle size of smaller than 1 mm;
(2) mixing said powdery carbon-containing raw material and said powdery calcium-containing raw material at weight ratios of 0.5-3:1;
(3) heating said mixture directly through partial combustion of said carbon-containing raw material in oxygen-containing atmospheres ... .
(The) weight ratios of the carbon-containing raw material to the calcium-containing raw material are 0.7-2:1.
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In essence, and in sum, we can manufacture Calcium Carbide using nothing but Limestone and Coal, with Coal able to serve double duty as the basic source of the thermal energy needed to drive the necessary chemical reactions and processes.
Actually, Coal can serve triple, or even quadruple, duty.
If the electro arc process is used to convert the Coal and Limestone blend into Calcium Carbide, and all references we have seen concerning commercial operations indicate that is at least currently the case, the electricity might be generated from Coal; and, the Carbon electrodes used in the process have historically been made from Coal Tar Pitch. As they discharge, the Carbon lost from them becomes entrained in the Calcium Carbide synthesis process.
But, all of the above relates to, ultimately, the traditional means of making Acetylene from Coal.
As we will see in reports to follow, there are alternative ways of manufacturing Acetylene much more directly from Coal; ways that don't require the intermediate synthesis of Calcium Carbide.
And, we will also see that, once we have the Acetylene, made indirectly, via Calcium Carbide, or, via processes we will document in those reports to follow, more directly, from Coal, there are, as might be suggested above by our excerpts from "US Patent Application 0110123428" and the Wikipedia, some very, very intriguing, and quite valuable, uses to which such Coal-based Acetylene can be put.