Nitrogen liquid fuels

Products of Combustion For lean mixtures, the products of combustion (POC) of a sulfur-free fuel consist of carbon dioxide, water vapor, nitrogen, oxygen, and possible small amounts of carbon monoxide and unburned hydrocarbon species. Figure 27-12 shows the effect of fuel-air ratio on the flue gas composition resulting from the combustion of natural gas. In the case of solid and liquid fuels, the... 

Until recently the atmospheric chemistry of nitrogen-containing compounds such as the hydrazines, which are widely used as fuels in military and space vehicles, has received comparatively little attention. N,N-dimethyIhydrazine (also UDMH = unsymmetrical dimethylhydrazine) is used in liquid-fueled rockets, and thus there Is a possibility that its use, storage, and handling could result in its release in the atmosphere. 

Syngas cleanup system - low or high temperature and processes used to remove sulfur, nitrogen, particulates, and other compounds that may impact the suitability of the syngas for specific applications (i.e., turbine and fuel cell for electric power generation, hydrogen production, liquid fuel production, or chemical production). 

For all three configurations, ethanol is used as the liquid fuel. It is pressurized to 90 psi in a fuel tank by high-pressure nitrogen, metered, and sent to the nozzle through a tube mounted in the center of the air chamber. 

The primary purpose of the energy conversion facility is the production of liquid or gaseous fuels most of the sulfur will be removed from these products. Liquid fuel streams will be hydro-desulfurized to meet combusion standards, with the sulfur transferred to the gas phase. In the case of oil shale, extensive hydrotreatment will be required to remove the refractory nitrogen compounds from the oil. With this degree of treatment, the sulfur will also be removed. 

Most gaseous fuels as well as some liquid fuels contain no or only small amounts of chemically bound nitrogen. In combustion of these fuels, the important source of NO is fixation of N2 in the combustion air. Molecular nitrogen, with its triple bond, is very stable, and only very reactive radicals may succesfully attack N2. The mechanisms of NO formation from N2 is quite well understood [274], and for many applications semiquantitative predictions of NO are within reach. 

The precious-metal platinum catalysts were primarily developed in the 1960s for operation at temperatures between about 200 and 300°C (1,38,44). However, because of sensitivity to poisons, these catalysts are unsuitable for many combustion applications. Variations in sulfur levels of as little as 0.4 ppm can shift the catalyst required temperature window completely out of a system s operating temperature range (44). Additionally, operation with liquid fuels is further complicated by the potential for deposition of ammonium sulfate salts within the pores of the catalyst (44). These low temperature catalysts exhibit NO conversion that rises with increasing temperature, then rapidly drops off, as oxidation of ammonia to nitrogen oxides begins to dominate the reaction (see Fig. 7). 

Assess the potential for minimizing nitrogen oxide (N0X) emissions from the six, high fuel-bound nitrogen liquids. 

The focus of this study is the chemistry of the partially pyrolyzed and oxidized liquid fuel which survives as pyrolysis and oxidative pyrolysis proceed. The experiments have been designed so that these products are not completely destroyed and can be recovered for analysis. The analyses include measurements of basic nitrogen, average molecular weight, molecular weight distribution and unsubstituted aromatics by gas chromatography, and Hi NMR studies to determine average molecular structure parameters. 

Synthetic liquid fuels derived from coal and shale will differ in some characteristics from conventional fuels derived from petroleum. For example, liquid synfuels are expected to contain significantly higher levels of aromatic hydrocarbons, especially for coal-derived fuels, and higher levels of bound nitrogen. These differences can affect the combustion system accepting such fuels in important ways. In continuous combustors, i.e. gas turbines, the increased aromatics content of coal-derived fuels is expected to promote the formation of soot which, in turn, will increase radiation to the combustor liner, raise liner temperature, and possibly result in shortened service life. Deposit formation and the emission of smoke are other potential effects which are cause for concern. Higher nitrogen levels in synfuels are expected to show up as increased emissions of N0X (NO+NO2) An earlier paper presented results of an experimental study on the effect of aromatics and combustor... 

In other fuel markets, coal liquids can be more competitive. Industrial boilers presently are not amenable to stack gas scrubbing. The same is true of smaller utility plants. In particular, peak load units require a clean, storable liquid fuel as an alternative to natural gas. However, the high viscosity of primary coal liquefaction products is undesirable for many of these applications. Also, their residual sulfur and nitrogen contents may be excessive as emission standards become more stringent. 

The liquids require a hydrorefining step to stabilize their reactive properties, to reduce the asphaltenes and preasphaltenes, to reduce sulfur, nitrogen, and oxygen, and to make the liquids more distillable. The extent of hydrorefining depends on the end use of liquids—fuel oil or chemical feedstocks. The objective of this work is to evaluate the hydrorefining processibility of ORC flash pyrolysis coal tar as a part of the tar characterization task. Results of the initial phase of catalyst screening tests are reported in this chapter. 

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