The Environmental Impact of Acetylene Compared to Impact of Propane-Chemtane 2
History of Acetylene
In 1836, Edmund Davy reported to the British Association his effort to produce pure potassium which produced a black substance which decomposed in water producing a flammable gas. Davy described the "olefiant bicarburet of hydrogen" gas as being excellent for illumination when burned. The black substance was potassium carbide and the flammable gas was acetylene, though it was not called by that name until 1860.
The carbide and its gas became commercial products. Gas street lights in New York provided illumination using the gas. A serious explosion occurred in the gas lines in New York. Torrey reported in 1839 that explosive copper acetylide was the product responsible for the explosion. Several researchers identified silver acetylide and copper acetylide as explosives and they were utilized in primers and blasting caps.
About 1860 and afterwards, Professor M.P. Berthelot studied the carbides and the flammable gas, which he called acetylene. He was the first to report the formula as C2H2 and noted it to be the smallest compound in the series C2nH2n-2 now known as alkynes (and also the dienes) which have two unsaturation sites. Berthelot explored the reactivity of acetylene and defined the initial steps used in large scale manufacturing. W`hler, in 1862, produced calcium carbide by heating a mixture of carbon, zinc and calcium. Addition of water to calcium carbide produces acetylene gas.
In 1892, J.T. Morehead used an electric furnace to heat a mixture of coal tar and lime attempting to produce calcium. A large black mass was produced and some of the product was tossed into a bucket of water, producing flame and black smoke. The substance was analyzed and was found to be calcium carbide which produced acetylene on contact with water. The process became the basis of the acetylene industry. J.T. Morehead's son, J.M. Morehead became a partner with E.F. Price. J. King and T.L. Willson to form the Willson Aluminum Company. The five plants could not be supported by producing aluminum and bronze so Willson pulled out of the business. Three of the plants began to specialize in calcium carbide, one at Niagara Falls, one in New York and one at Ontario, Canada. J.M. Morehead was at the Niagara Falls plant which became the Acetylene, Light, Heat and Company. The business continued successfully and in 1898, the name was changed to Union Carbide Corporation. Numerous other companies and nations began to produce calcium carbide by 1900.
Large quantities of liquid acetylene in steel containers were shipped for use. By 1896, numerous large explosions had occurred. The liquid or gas could be detonated by spark or heat when the pressure exceeded about 28 psi. Claude and Hess described the solubility of acetylene in acetone. Berthelot and Vielle reported that an acetone solution of acetylene was vastly safer than pure acetylene. Le Chatelier described the use of porous stone inside the cylinders. The dissolved acetylene industry based on these discoveries developed worldwide in the years 1901-1904. The early principle use of acetylene was as an illuminant.
Priestly discovered the element oxygen in 1774 and it brought about a dramatic change in chemistry and science in general. Commercial production of oxygen began in 1886. In 1895, Joule-Thomson demonstrated the process for liquefaction of air. In 1902, Linde developed a separation process which gave birth to the large scale commercial oxygen industry.
The acetylene industry came together with the oxygen industry in the first experiments in 1901 by Fouché and Picard to produce the oxy-acetylene flame. They did research in welding starting about 1903 developing a series of torch designs. Bournonville took an oxy-acetylene torch to the U.S.A. in 1906. Welding rapidly became a widespread technology in American manufacturing. Fletcher produced the first oxygen lance in 1888 by passing oxygen through a heated iron pipe. The iron caught fire with intense heat. In 1901 the oxygen lance was used by burglars to cut into a safe. Acetylene is the best gas for welding and it became the principle gas for use in cutting. In a sense, it became the traditional choice for cutting despite the effectiveness of other fuel gases.
The chemistry for industrial production of calcium carbide was developed in the late 1800s and has been used for over 100 years. The reaction follows.
CaO + 3 C CaC2 + CO
The reaction process is fairly efficient, but there is residue from the kilns and the overall process which must be disposed of. Landfill is the primary method for disposing of solid residue. The process water must be disposed of for cleaning as an industrial effluent.
Environmental Impact
The National Environmental Policy Act of 1969 (NEPA) defined the legal effort to regulate the effect of man's developments on the environment. It was signed into law January 1, 1990. NEPA defined the requirements for an environmental impact statement. Primarily this means reporting predictions of the effects on the environment, which could be brought about by a project, such as building a dam and creating a large lake. The environmental impact statement describes (1) the overall impact (2) unavoidable effects (3) effects which could be minimized by some alternative (4) short term versus long term effects and (5) permanent damaging effects on the environment.
This document is not an actual environmental impact study of a new proposed project. This document does not attempt to provide a comprehensive economic analysis, because such would be beyond its scope and purpose. Rather, it is consideration of environmental effects which can be minimized by using Propane-Chemtane 2 in place of Acetylene for metal cutting. What environmental impact does the use of Acetylene have? There are a number of areas of impact in (1) air quality (2) energy utilization (3) landfill and soil quality (4) water quality and (5) vegetation and wildlife. These are the normal areas for evaluation in an environmental impact analysis.
Impact of Acetylene
The use of acetylene does have an impact on air quality. The 1892 work of J.T. Morehead with an electric furnace produced commercial quantities of calcium carbide. The product produced flame and black smoke when placed in water. After lighting an acetylene torch, smoke is produced until the oxygen is adjusted. In closed quarters, or in a building with numerous torches, the amount of soot and smoke may be considerable. This is a localized effect on air quality.
Acetylene is more costly than other fuel gases. One major reason for the expense is the amount of energy required in production. It is largely in the form of electrical energy for the actual production stage. Process steam or other lower cost methods may be used for other stages of production. Acetylene production does carry a premium price due to energy utilization during production. The cylinders also require steel for their production which has an energy impact.
Acetylene production does have an impact on landfill and soil quality. Some of the residue from calcium carbide production must be disposed of by landfill. The cylinders utilized to transport acetylene, ultimately, must be disposed of by landfill. Landfill always carries some potential risk to soil quality. The products from acetylene production are not biodegradable.
Water quality can be affected by leaching of products from a landfill. Process water must be treated before it can be discharged as effluent. Acetylene production produces process water at different steps for production of the carbide and for producing acetylene from the carbide.
Vegetation or wildlife can be affected by landfill or water quality due to leaching of products from the landfill. A considerable quantity of residue results from the production and use of acetylene.
Impact of Propane-Chemtane 2
The use of propane-Chemtane 2 has a limited impact on air quality. Black smoke and soot is not produced when lighting a torch. There is no significant quantity of smoke from multiple torches. Propane-Chemtane 2 has a clean burning flame and produces carbon dioxide and water, just as acetylene does.
Propane-Chemtane 2 is costs significantly less than other fuel gases such as acetylene. Propane is refined from light fractions of crude oil. The Chemtane 2 concentrate is composed of hydrocarbons obtained from distillation of crude oil. The low expense results from the low cost of production and the small amount of energy required for its production. It can be obtained with a gas separator or in low temperature distillation. Process steam may be used for its production. The cylinders used for propane-Chemtane 2 are low-pressure units requiring only a small amount of steel for their production which has little energy impact.
Propane-Chemtane 2 does not have impact on landfill and soil quality. The cylinders utilized to transport propane-Chemtane 2 can be recycled and do not have to be disposed of in a landfill. Thus, there is not a significant risk to soil quality. There are no additional products from propane-Chemtane 2 to be disposed of.
Water quality can be affected by leaching of products from a landfill, however nothing from propane-Chemtane 2 goes into a ladfill. Process water from refining must be treated before it can be discharged as effluent. Water that does not meet standards for discharge is often injected into a disposal well.
Vegetation or wildlife can be affected by landfill or water quality due to leaching of products from the landfill. A negligible quantity of residue results from the production of propane-Chemtane 2 and thus landfill is not really an issue.
Propane-Chemtane 2 is a product mix obtained from crude oil refining. Refineries are very efficient at converting all of crude oil into products. Lost and waste really only a problem with the heavy fractions such as asphalt. Since propane-Chemtane 2 is produced from light fractions of crude oil there is no significant waste or residue left behind.
Bibliography
Miller, Samuel Aaron. Acetylene: its properties, manufacture and uses. New York: Academic Press, 1965.
Rau, John G. and David C. Wooten, Editors. Environmental Impact Analysis Handbook. New York: McGraw-Hill Book Company, 1980.
More Environmental Topics:
Acetylene Marketplace and the Future
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