Natural gas to oxygenates

CONCEPTUAL SCHEMES OF THE PARTIAL OXIDATION OF NATURAL GAS TO OXYGENATES... 

The Texaco process was first utilized for the production of ammonia synthesis gas from natural gas and oxygen. It was later (1957) appHed to the partial oxidation of heavy fuel oils. This appHcation has had the widest use because it has made possible the production of ammonia and methanol synthesis gases, as well as pure hydrogen, at locations where the lighter hydrocarbons have been unavailable or expensive such as in Maine, Puerto Rico, Brazil, Norway, and Japan. 

Nature hasn t provided any convenient sources of pure CO and H2. There s some of each contained in natural gas but usually not in sufficient quantities to justify going after it. But these two compounds, either in the combined state or separate, are readily convertible to a number of commercial compounds. With that as a motivator, several processes have been developed to convert natural gas to synthesis gas. Natural gas is largely methane (CH4), and that provides a source of carbon and hydrogen. Air or water provides the other necessary ingredient, oxygen. 

All commercial processes involve either separation of nitrogen from air by cryogenic distillation or combustion of air with natural gas to remove oxygen. In the former process, air is liquefied and the liquid air is subjected to fractional distillation to separate its components. 

Filament-wound structures are often used to store fluid under pressure fuel storage tanks, rocket motor cases, natural gas, and oxygen storage tanks. In some cases, the filament-wound structure is subjected to external pressure a diving bell or submarine. Filament winding has... 

Dissoived-gas units have found application in rcfiuei y operations where air can be used as the gas and where large areas are available. In treating produced water for injection, it is desirable to use natural gas to exclude oxygen. This requires venting the gas or installation of a vapor-recovery unit. Field experience with dissolved natural gas units has not been as successful as with dispersed gas units. 

An amazing variety of glass apparatus can be constructed by using simply a torch and low-pressure natural gas and oxygen supplies. Also, a pair of didym-ium-tinted glasses is a necessity to eliminate the yellow glare of sodium emission which occurs when borosilicate glass is heated. 

Because water is the cheapest and most readily available source of hydrogen, all large-scale, industrial methods for producing hydrogen use an inexpensive reducing agent such as hot iron, carbon, or methane (natural gas) to extract the oxygen from steam ... 

A separate Oxygen Transport Membrane (OTM) Syngas Alliance was formed in 1997 and includes Amoco Production Company, British Petroleum, Praxair, Statoil, Foster Wheeler and Sasol Technology. This alliance is developing ceramic membrane technology that will economically convert natural gas to synthesis gas190. 

Partial oxidation (POX) of natural gas with oxygen is carried out in a high-pressure, refractory-lined reactor. The ratio of oxygen to carbon is carefully controlled to maximize the yield of CO and H2 while maintaining an acceptable level of C02 and residual methane and minimizing the formation of soot. Downstream equipment is provided to remove the large amount of heat generated by the oxidation reaction,... 

A recent development of a ceramic membrane appears to be promising for selectively removing oxygen from air. Multi-channel membrane elements have been fabricated for that purpose [Anonymous, 1995]. The membrane has the potential for reducing the cost of converting natural gas to synthesis gas. 

In fuel cells systems, as reported in recent patents [13,14], membranes wUl be present not only as PEM (proton-exchange membrane), which allows protons to pass from the anode to the cathode where they are combined with oxygen and electrons to produce water, but also for the production and purification of the H2 (Figure 43.3). This system provides a C02-selective membrane process for the purification and water gas shift reaction of a reformed gas, generated from on-board reforming of a fuel, e.g., hydrocarbon, gasoline, diesel, methanol, or natural gas, to hydrogen for fuel cell vehicles. 

Oxidation-reduction reactions Many organic compounds can be converted to other compounds by oxidation and reduction reactions. For example, suppose that you wish to convert methane, the main constituent of natural gas, to methanol, a common industrial solvent and raw material for making formaldehyde and methyl esters. The conversion of methane to methanol may be represented by the following equation, in which [O] represents oxygen from an agent such as copper(II) oxide, potassium dichromate, or sulfuric acid. 

The oil tube/atomizer section was removed from the dual fuel burner and an oxy/fuel burner was inserted in its place. The burner retrofit package including the natural gas and oxygen flow control trains were prefabricated to prevent furnace downtime. The oxy/fuel flow controls and safety switches were interlocked to the conventional air/fuel controls, thus creating a hybrid air-oxy/fuel combustion system. 

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