Fire-air

Chemical Regeneration. In most MHD system designs the gas exiting the toppiag cycle exhausts either iato a radiant boiler and is used to raise steam, or it exhausts iato a direct-fired air heater and is used to preheat the primary combustion air. An alternative use of the exhaust gas is for chemical regeneration, ia which the exhaust gases are used to process the fuel from its as-received form iato a more beaeftcial oae. Chemical regeaeratioa has beea proposed for use with aatural gas and oil as well as with coal (14) (see Gas, natural Petroleum). 

Steam is the usual heating medium, and a standard heater arrangement consists of a main heater before the circulating fan. When steam is not available or the diying load is small, electricalheat can be used. For temperatures above 450 K, products of combustion can be used, or indirect-fired air heaters. 

Auxiliary Equipment On direct-heat rotating equipment, a combustion chamber is required for high temperatures and finned steam coils are used for low temperatures. If contamination of the produc t with combustion gases is undesirable on direct-heat units, indirect gas- or oil-fired air heaters may be employed to achieve temperatures in excess of available steam. 

U.S. Interagency Team Proposes Program to Quantify Effects of Kuwait Oil Fires," /. Air Waste Management Assoc. 41,(6), June 1991. 

External Combustor (experimental). The heat exehanger used for an external-combustion gas turbine is a direct-fired air heater. The air heater s goal is to achieve high temperatures with a minimum pressure decrease. It consists of a rectangular box with a narrow convection section at the top. The outer casings of the heater consist of carbon steel lined with lightweight blanket material for insulation and heat re-radiation. 

Specification for dedicated liquefied petroleum gas appliances - Mobile and portable non-domestic forced convection direct fired air heaters. Superseded BS 4096 1967... 

This subject has received little attention in the context of pressure vessel bursts. Pittman (1976) studied it using a two-dimensional numerical code. However, his results are inconclusive, because the number of cases he studied was small and because the grid he used was coarse. Baker et al. (1975) recommend, on the basis of experimental results with high explosives, the use of a method described in detail in Section 6.3.3. That is, multiply the volume of the explosion by 2, read the overpressure and impulse from graphs for firee-air bursts, and multiply them by a factor depending on the range. 

Pre-1600 Alchemists sought to turn base metals (iron, zinc, lead) into gold using the four elements — earth, fire, air, and water. 

Obtained upon heating HgO and was termed "fire air" or "dephlogisti-cated air". 

Greek philosophers thought that everything could be learned by logical thinking. They did not believe in experimenting or observing. Therefore, they made many mistakes. Today scientists 1 know that neither fire, air, earth, nor water are really elements, but it was many years before the ideas of these early thinkers were questioned. 

Earth without water can produce nothing, nor can water quicken anything into growth without earth and as earth and water are mutually indispensable in the production of fruit, so fire cannot operate without air, or air without fire. For fire has no life without air and without fire air possesses neither heat nor dryness. 

Each element is in its turn decomposed and regenerated by that which is contained in it. For you should know that every element contains the three others. In air, for instance, there is fire, water, and earth. This assertion may appear incredible, but it is nevertheless true. In like manner, fire includes air, water, and earth, since otherwise it could generate nothing. Water contains fire, air, and earth for if it did not, there could be no growth. At the same time, each element is distinct, though each contains the others. All this is found by distillation in the separation of the elements. 

In 1766 Henry Cavendish (1731— 1810) identified the gas from the iron fihngs-plus-acid reaction as fire air and determined that the gas, when burned in air, produced water. He is given credit for the discovery of hydrogen even though the chemical reaction that produced the gas had been known for hundreds of years. In 1783 Antoine Lavoisier (1743—1794) gave the gas its name hydrogen. 

The control of NO from stationary sources includes techniques of modification of the combustion stage (primary measures) and treatment of the effluent gases (secondary measures). The use oflow-temperature NO,.burners, over fire air (OFA), fiue gas recirculation, fuel reburning, staged combustion and water or steam injection are examples of primary measures they are preliminarily attempted, extensively applied and guarantee NO reduction levels of the order of 50% and more. However, they typically do not fit the most stringent emission standards so that secondary measures or flue gas treatment methods must also be applied. 

External heating Supplemental heat is required during start-up and potentially turndown conditions to establish proper regeneration kinetics. A direct fired air preheater and torch oil in the regenerator are typically used. The ESP is de-energized whenever these fuel sources are in use. 

Hjelm prepared purified molybdic acid and obtained a pure regulus, which he examined with the microscope. In an unsuccessful attempt to fuse the molybdenum, he raised the temperature of the wind-furnace with fire-air (oxygen) obtained by adding two pounds of crude pyrolusite to the fire (24). 

Antoine Baum , 1728-1804. French pharmacist and chemist. Author of a Chymie expenmentale et raisonnee in which he discussed chemical apparatus, chemical affinity, fire, air, earth, water, sulfur, gypsum, alum, clay, niter, gunpowder, borax, arsenic, glass, porcelain, and the common acids, alkalies, metals, and ores used m 1773. His hydrometer scale is still used. He was one of the first chemists to investigate platinum... 

Swedish alchemist K.W. Scheele (1742— 1786) separated from saltpeter its fire-air , now known as oxygen. He also obtd glycerin and identified chlorine and fluorine (Ref 58,... 

I believe it is possible [he said] to establish in the realm of the imagination, a law ofthejbur elements which classifies various kinds of material imagination by their coimections with fire, air, water or earth. .. A material element must provide its own substance, its particular rules and poetics. It is not simply coincidental that primitive philosophies often made a decisive choice along these lines. They associated with their formal principles one of the four fundamental elements, which thus became signs of philosophic disposition. 

So Priestley s dephlogisticated air had a hidden past. Scheele s work was still unknown in 1775, since the apothecary did not announce his findings (which included the fact that fire air comprised one-fifth of common air) until 1777-... 

Kanada, a Nyaya-Vaisheshika philosopher, who lived -600 BCE, considered that matter was composed of four types of atoms, earth, fire, air, and water. Atoms reacted with the aid of an invisible force (adrsta) to form biatomic molecules and triatomic molecules (6-8). He stated that there were five elements earth, fire, air, water, and space. Each atom also had qualities such as odor, taste, color and a sense of touch (S). 

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