Hi lenny It seems kids world wide got up to the same old tricks, it's a wonder we are still here. Boomm up there, she goes.
Regards Ray ----- Original Message ----- From: "Lenny McHugh" <[EMAIL PROTECTED]> To: "Handyman-Blind" <[email protected]> Sent: Friday, October 05, 2007 11:20 PM Subject: Re: [BlindHandyMan] How is acetylene made? > Ray, This also brings back some fantastic memories. > When I was a kid calcium carbide was readily available. I wonder what > happened to my old carbide lantern and cannon? Anyway the memories were > about some really stupid things that we did. We had a lot of fun with > calcium carbide > , an old paint can and a pack of matches. We took the paint can and > punched > a nail hole in the bottom. Then drop in a small piece of carbide and spit > on > it. As soon as it started working I would place the lid back on the can. > Now > aiming the can where nothing could get hurt or broke I set it on the > ground > and held it in place with my foot. then lighting a match and holding it > near the hole in the back of the can there was a loud boom and the lid > would > sail about 20 feet. We use to purchase a two pound container for under > $2.00 > and this gave us several weeks of entertainment. > There was also a big bang cannon that I had. It was miniature replica of > an > old cannon that had a place for a very small piece of calcium carbide > . It had a place where you added water and had a flint spark igniter > similar > to that of an old Zippo lighter. IT This toy made a much safer loud bang. > We > used the carbide lantern when we went camping, not with my parents but > with > 5 or 6 other ten year old kids. > Thanks for the memories. > By the way the paint can cannon was about 50 years ago. > > ----- Original Message ----- > From: "Ray Boyce" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Monday, October 08, 2007 4:13 AM > Subject: [BlindHandyMan] How is acetylene made? > > > Acetylene is a > colorless, > combustible gas with a distinctive > odor. > When acetylene is liquefied, compressed, heated, or mixed with air, it > becomes highly explosive. As a result special precautions are required > during its > production and handling. The most common use of acetylene is as a raw > material for the production of various organic chemicals including > 1,4-butanediol, > which is widely used in the preparation of > polyurethane > and > polyester > plastics. The second most common use is as the fuel component in > oxy-acetylene > welding > and metal cutting. Some commercially useful acetylene compounds include > acetylene black, > which is used in certain dry-cell batteries, and > acetylenic > alcohols, which are used in the synthesis of vitamins. > > Acetylene was discovered in 1836, when Edmund Davy was experimenting with > potassium > carbide. > One of his chemical reactions produced a > flammable > gas, which is now known as acetylene. In 1859, Marcel Morren successfully > generated acetylene when he used carbon electrodes to strike an electric > arc > in > an atmosphere of hydrogen. The electric arc > tore > carbon atoms away from the electrodes and bonded them with hydrogen atoms > to > form acetylene molecules. He called this gas carbonized hydrogen. > > By the late 1800s, a method had been developed for making acetylene by > reacting > calcium carbide > with water. This generated a controlled flow of acetylene that could be > combusted in air to produce a brilliant white light. Carbide lanterns were > used > by miners and carbide lamps were used for street illumination before the > general availability of electric lights. In 1897, Georges Claude and A. > Hess > noted > that acetylene gas could be safely stored by dissolving it in > acetone. > Nils Dalen used this new method in 1905 to develop long-burning, automated > marine and railroad signal lights. In 1906, Dalen went on to develop an > acetylene torch > for welding and metal cutting. > > In the 1920s, the German firm > BASF > developed a process for manufacturing acetylene from natural gas and > petroleum-based > hydrocarbons. > The first plant went into operation in Germany in 1940. The technology > came > to the United States in the early 1950s and quickly became the primary > method > of producing acetylene. > > Demand for acetylene grew as new processes were developed for converting > it > into useful plastics and chemicals. In the United States, demand peaked > sometime > between 1965 and 1970, then fell off sharply as new, lower-cost > alternative > conversion materials were discovered. Since the early 1980s, the demand > for > acetylene has grown slowly at a rate of about 2-4% per year. > > In 1991, there were eight plants in the United States that produced > acetylene. Together they produced a total of 352 million lb (160 million > kg) > of acetylene > per year. Of this production, 66% was derived from natural gas and 15% > from > petroleum processing. Most acetylene from these two sources was used on or > near the site where it was produced to make other organic chemicals. The > remaining 19% came from calcium carbide. Some of the acetylene from this > source > was used to make organic chemicals, and the rest was used by regional > industrial gas producers to fill pressurized cylinders for local welding > and > metal > cutting customers. > > In Western Europe, natural gas and petroleum were the principal sources of > acetylene in 1991, while calcium carbide was the principal source in > Eastern > Europe and Japan. > > Raw Materials > > Acetylene is a hydrocarbon consisting of two carbon atoms and two hydrogen > atoms. Its chemical symbol is C2H2. For commercial purposes, acetylene can > be > made from several different raw materials depending on the process used. > > The simplest process reacts calcium carbide with water to produce > acetylene > gas and a calcium carbonate > slurry, > called > hydrated lime. > The chemical reaction may be written as CaC2 + 2 H2O ? C2H2 + Ca(OH)2. > > Other processes use natural gas, which is mostly > methane, > or a petroleum-based hydrocarbon such as crude oil, > naphtha, > or bunker C oil as raw materials. Coal can also be used. These processes > use > high temperature to convert the raw materials into a wide variety of > gases, > including hydrogen, > carbon monoxide, > carbon dioxide, > acetylene, and others. The chemical reaction for converting methane into > acetylene and hydrogen may be written 2 CH4 ? C2H2 + 3 H2. The other gases > are > the products of combustion with oxygen. In order to separate the > acetylene, > it is dissolved in a > solvent > such as water, > anhydrous ammonia, > chilled > methanol, > or acetone, or several other solvents depending on the process. > > The Manufacturing > Process > > There are two basic conversion processes used to make acetylene. One is a > chemical reaction process, which occurs at normal temperatures. The other > is > a > thermal cracking process, which occurs at extremely high temperatures. > > Here are typical sequences of operations used to convert various raw > materials into acetylene by each of the two basic processes. > > Chemical reaction process > > Acetylene may be generated by the chemical reaction between calcium > carbide > and water. This reaction produces a considerable amount of heat, which > must > be removed to prevent the acetylene gas from exploding. There are several > variations of this process in which either calcium carbide is added to > water > or water is added to calcium carbide. Both of these variations are called > wet processes because an excess amount of water is used to absorb the heat > of > the reaction. A third variation, called a dry process, uses only a limited > amount of water, which then > evaporates > as it absorbs the heat. The first variation is most commonly used in the > United States and is described below. > 1. Most high-capacity acetylene generators use a rotating > screw conveyor > to feed calcium carbide granules into the reaction chamber, which has been > filled to a certain level with water. The granules measure about 0.08 in x > 0.25 > in (2 mm x 6 mm), which provides the right amount of exposed surfaces to > allow a complete reaction. The feed rate is determined by the desired rate > of > gas flow and is controlled by a pressure switch in the chamber. If too > much > gas is being produced at one time, the pressure switch opens and cuts back > the feed rate. > 2. To ensure a complete reaction, the solution of calcium carbide granules > and water is constantly > agitated > by a set of rotating paddles inside the reaction chamber. This also > prevents > any granules from floating on the surface where they could over-heat and > ignite > the acetylene > 3. The acetylene gas bubbles to the surface and is drawn off under low > pressure. As it leaves the reaction chamber, the gas is cooled by a > spray > of water. This water spray also adds water to the reaction chamber to keep > the reaction going as new calcium carbide is added. After the gas is > cooled, > it passes through a flash arrester, which prevents any accidental > ignition > from equipment downstream of the chamber. > 4. As the calcium carbide reacts with the water, it forms a slurry of > calcium carbonate, which sinks to the bottom of the chamber. Periodically > the reaction > must be stopped to remove the built-up slurry. The slurry is drained from > the chamber and pumped into a holding pond, where the calcium carbonate > settles > out and the water is drawn off. The thickened calcium carbonate is then > dried and sold for use as an industrial waste water treatment agent, acid > neutralizer, > or soil > conditioner > for road construction. > > Thermal cracking process > > Acetylene may also be generated by raising the temperature of various > hydrocarbons to the point where their atomic bonds break, or crack, in > what > is known > as a thermal cracking process. After the hydrocarbon atoms break apart, > they > can be made to rebond to form different materials than the original raw > materials. > This process is widely used to convert oil or natural gas to a variety of > chemicals. > > There are several variations of this process depending on the raw > materials > used and the method for raising the temperature. Some cracking processes > use > an electric arc to heat the raw materials, while others use a combustion > chamber that burns part of the hydrocarbons to provide a flame. Some > acetylene > is generated as a coproduct of the steam cracking process used to make > ethylene. > In the United States, the most common process uses a combustion chamber to > heat and burn natural gas as described below. > 1. Natural gas, which is mostly methane, is heated to about 1,200° F (650° > C). Preheating the gas will cause it to self-ignite once it reaches the > burner > and requires less oxygen for combustion. > 2. The heated gas passes through a narrow pipe, called a venturi, where > oxygen is injected and mixed with the hot gas. > 3. The mixture of hot gas and oxygen passes through a > diffuser, > which slows its velocity to the desired speed. This is critical. If the > velocity is too high, the incoming gas will blow out the flame in the > burner. If > the velocity is too low, the flame can flash back and ignite the gas > before > it reaches the burner. > 4. The gas mixture flows into the burner block, which contains more than > 100 > narrow channels. As the gas flows into each channel, it self-ignites and > produces > a flame which raises the gas temperature to about 2,730° F (1,500° C). A > small amount of oxygen is added in the burner to stabilize the combustion. > 5. The burning gas flows into the reaction space just beyond the burner > where the high temperature cause about one-third of the methane to be > converted > into acetylene, while most of the rest of the methane is burned. The > entire > combustion process takes only a few milliseconds. > 6. The flaming gas is quickly quenched with water sprays at the point > where > the conversion to acetylene is the greatest. The cooled gas contains a > large > amount of carbon monoxide and hydrogen, with lesser amounts of carbon > soot, > plus carbon dioxide, acetylene, methane, and other gases. > 7. The gas passes through a > water scrubber, > which removes much of the carbon soot. The gas then passes through a > second > scrubber where it is sprayed with a solvent known as N-methylpyrrolidinone > which > absorbs the acetylene, but not the other gases. > 8. The solvent is pumped into a separation tower where the acetylene is > boiled out of the solvent and is drawn off at the top of the tower as a > gas, > while > the solvent is drawn out of the bottom. > > Storage and Handling > > Because acetylene is highly explosive, it must be stored and handled with > great care. When it is transported through pipelines, the pressure is kept > very > low and the length of the pipeline is very short. In most chemical > production operations, the acetylene is transported only as far as an > adjacent plant, > or "over the fence" as they say in the chemical processing business. > > When acetylene must be pressurized and stored for use in oxy-acetylene > welding and metal cutting operations, special storage cylinders are used. > The cylinders > are filled with an absorbent material, like > diatomaceous earth, > and a small amount of acetone. The acetylene is pumped into the cylinders > at > a pressure of about 300 psi (2,070 kPa), where it is dissolved in the > acetone. > Once dissolved, it loses its explosive capability, making it safe to > transport. When the cylinder valve is opened, the pressure drop causes > some > of the > acetylene to vaporize into gas again and flow through the connecting > hose > to the welding or cutting torch. > > Quality Control > > Grade B acetylene may have a maximum of 2% impurities and is generally > used > for > oxyacetylene welding > and metal cutting. Acetylene produced by the chemical reaction process > meets > this standard. Grade A acetylene may have no more than 0.5% impurities and > is generally used for chemical production processes. Acetylene produced by > the thermal cracking process may meet this standard or may require further > purification, > depending on the specific process and raw materials. > > The Future > > The use of acetylene is expected to continue a gradual increase in the > future as new applications are developed. One new application is the > conversion of > acetylene to ethylene for use in making a variety of polyethylene > plastics. > In the past, a small amount of acetylene had been generated and wasted as > part > of the steam cracking process used to make ethylene. A new > catalyst > developed by Phillips Petroleum allows most of this acetylene to be > converted into ethylene for increased yields at a reduced overall cost. > > > > > To listen to the show archives go to link > http://acbradio.org/handyman.html > or > ftp://ftp.acbradio.org/acbradio-archives/handyman/ > > The Pod Cast address for the Blind Handy Man Show is. > http://www.acbradio.org/news/xml/podcast.php?pgm=saturday > > Visit The Blind Handy Man Files Page To Review Contributions From Various > List Members At The Following address: > http://www.jaws-users.com/handyman/ > > Visit the archives page at the following address > http://www.mail-archive.com/[email protected]/ > > If you would like to join the Blind Computing list, then visit the > following > address for more information: > http://jaws-users.com/mailman/listinfo/blind-computing_jaws-users.com > > For a complete list of email commands pertaining to the Blind Handy Man > list > just send a blank message to: > [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > > To listen to the show archives go to link > http://acbradio.org/handyman.html > or > ftp://ftp.acbradio.org/acbradio-archives/handyman/ > > The Pod Cast address for the Blind Handy Man Show is. > http://www.acbradio.org/news/xml/podcast.php?pgm=saturday > > Visit The Blind Handy Man Files Page To Review Contributions From Various > List Members At The Following address: > http://www.jaws-users.com/handyman/ > > Visit the archives page at the following address > http://www.mail-archive.com/[email protected]/ > > If you would like to join the Blind Computing list, then visit the > following address for more information: > http://jaws-users.com/mailman/listinfo/blind-computing_jaws-users.com > > For a complete list of email commands pertaining to the Blind Handy Man > list just send a blank message to: > [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.488 / Virus Database: 269.14.1/1050 - Release Date: 10/4/2007 > 5:03 PM >
