Towns gas

Two schemes (BGC [British Gas Corporation]/ICI [87] [139] and Lurgi Recatro [259]) used low-temperature adiabatic reformers (precursor for the prereforming teehnology, refer to Sections 1.2.5 and 5.3.2) in parallel or in series. 

The Topsoe teehnology [493] used a single tubular reforming step operating at lower steam-to-carbon ratio and reformer exit temperature than the two other schemes and thus met the required gas eomposition and heating value. 

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Carbon monoxide and excess steam are normally passed over a cobalt catalyst at about 250-300 C resulting in greater than 99% conversion of CO to COj. This conversion reaction is widely used in oil or solid fuel gasification processes for the production of town gas or substitute natural gas. ... 

Low Temperature Carbonization. Low temperature carbonization, when the process does not exceed 700°C, was mainly developed as a process to supply town gas for lighting purposes as well as to provide a smokeless (devolatilized) soHd fuel for domestic consumption (30). However, the process by-products (tars) were also found to be valuable insofar as they served as feedstocks (qv) for an emerging chemical industry and were also converted to gasolines, heating oils, and lubricants (see Gasoline and OTHER motor fuels Lubrication and lubricants) (31). 

Until the end of World War II, coal tar was the main source of these aromatic chemicals. However, the enormously increased demands by the rapidly expanding plastics and synthetic-fiber industries have greatly outstripped the potential supply from coal carbonization. This situation was exacerbated by the cessation of the manufacture in Europe of town gas from coal in the eady 1970s, a process carried out preponderantly in the continuous vertical retorts (CVRs), which has led to production from petroleum. Over 90% of the world production of aromatic chemicals in the 1990s is derived from the petrochemical industry, whereas coal tar is chiefly a source of anticorrosion coatings, wood preservatives, feedstocks for carbon-black manufacture, and binders for road surfacings and electrodes. 

Until 1960—1970, in countries where natural gas was not available, large amounts of coal were carbonized for the production of town gas, as well as a grade of coke which, although unsuitable for metallurgical use, was satisfactory as a domestic fuel in closed stoves. The early cast-iron and siUca horizontal retorts used at gasworks were replaced by continuous vertical retorts. These operated at flue temperatures of 1000—1100°C. The volatile products were rapidly swept from the retort by the introduction of steam at 10—20% by weight of the coal carbonized. 

Carbon monoxide was discovered in 1776 by heating a mixture of charcoal and 2inc oxide. It provided a source of heat to industry and homes as a component of town gas and was used as a primary raw material in German synthetic fuel manufacture during World War II its compounds with transition metals have been studied extensively (see Carbonyls). Most recently, carbon monoxide emission from vehicle exhausts has been recognized as a primary source of air pollution (qv). 

Steam reforming is the reaction of steam with hydrocarbons to make town gas or hydrogen. The first stage is at 700 to 830°C (1,292 to 1,532°F) and 15-40 atm (221 to 588 psih A representative catalyst composition contains 13 percent Ni supported on Ot-alumina with 0.3 percent potassium oxide to minimize carbon formation. The catalyst is poisoned by sulfur. A subsequent shift reaction converts CO to CO9 and more H2, at 190 to 260°C (374 to 500°F) with copper metal on a support of zinc oxide which protects the catalyst from poisoning by traces of sulfur. 

Naphthalene Prttpane Coal gas (town gas) Petroleum Toluene Water gas Hydrogen ... 

Cast-iron pipes were used for the mains in the early stages of town gas supply, their sockets being sealed with tarred rope, oakum, or lead. Originally the connection pipes were lead and later of galvanized or coal-tarred forged iron. After the defeat of Napoleon in 1815, there was a surplus of cheap musket barrels, and these... 

Naphtha vapor from a relief valve on a town gas plant in the UK was ignited by a flare stack. The flame impinged on the napththa line, which burst, starting a secondary fire [7]. 

Eor crimped metal ribbon arresters it provides the following equation for the maximum flame speed obtained by Cubbage (1959) for the stoppage of town gas-air mixture detonations by arresters with a crimp height of 0.017 inches ... 

Cubbage, P. A. 1959. Flame Traps for Use with Town Gas/Air Mixtures. Gas Council Research Communication GC 63. The Gas Council, London, England. 

This is valid for the same degree of gas mixture turbulence and the same ignition source and is illustrated in Figure 7-58. Influence of the vessel shape is shown in Figure 7-56. The behavior of propane is considered representative of most flammable vapors including many solvents [54]. The maximum explosion pressure does not follow the cubic law and is almost independent of the volume of a vessel greater than 1 liter. For propane, town gas, and hydrogen, the volume relationship can be expressed ... 

Gas fuel Town gas Natural gas Methane Butane Propane Carbon monoxide... 

A graphical representation as shown in Figure 19.11. This is drawn in the logarithm-logarithm format and allows a rapid estimate of pressure loss to be expected. Note that this particular chart is in imperial units and is drawn for use with town gas. A correction for specific gravity would be needed for natural gas. 

The effect of the air is to depress the vapor dew point temperature. A further advantage is that the physical properties of the gas can be made to simulate another gas, e.g. natural gas or manufactured town gas. Such a simulated gas will produce the same heat release through a burner if the supply pressure is the same. This is characterized by a term known as the Wobbe number W) ... 

A test procedure which has proved very useful was first described by Hatfield. The samples are cylinders 32 x 12-5 mm in diameter with a standard abraded finish which are supported on open-ended refractory boats in a tubular furnace. In the original test the atmosphere, which was produced by burning towns gas with a 50% excess of air, was passed over the specimens at a standard velocity after first preheating to test temperature over refractory packing in a separate furnace chamber. More latterly, natural gas has been used with suitable modification of air gas ratio to give... 

A fuel gas under pressure which may be hydrogen, towns gas, acetylene or propane. With special nozzles, low-pressure acetylene or butane can be used, but it is not common practice. The use of single cylinders of fuel gas is now giving way (except under site conditions) to the gases drawn from bulk liquid storage. All modern installations use flowmeters in the gaseous feeds. 

Pipelines have a long history. In ancient times, pipelines were used for water transport. Examples are still visible in archeologic areas. However, it is clear that these early constructions could not bear large pressures. The advent of gas pipelines started between 1820 and 1830 with the distribution of town gas. Nowadays pipelines are indispensable in petroleum industries for the transport of various materials, including natural gas, crude oil of various types, and refined products. 

Violent explosions occur when fluorine directly contacts liquid hydrocarbons, even at —210 with anthracene or turpentine, or solid methane at — 190°C with liquid fluorine. Many lubricants ignite in fluorine [1,2]. Contact and reaction under carefully controlled conditions with catalysis can now be effected smoothly [3], Gaseous hydrocarbons (town gas, methane) ignite in contact with fluorine, and mixtures with unsaturated hydrocarbons (ethylene, acetylene) may explode on exposure to sunlight. Each bubble of fluorine passed through benzene causes ignition, but a rapid stream may lead to explosion [4],... 

Benzorbon A process for separating and recovering benzene from coke-oven gas and town gas by adsorption on activated carbon. Developed in 1930 by Luigi. 

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