Gas candle

Related Terms Aerosol, see Aerosols, p.3 Blau gas, Fischer Tropsch gas. Synthesis gas, Water gas, see Coal, p.44 Candles, gas, see Lighters, p.l37 Coal gas Coal gas, compressed, see Coal, p.44... 

Materials and Reactions. Candle systems vary in mechanical design and shape but contain the same genetic components (Fig. 1). The candle mass contains a cone of material high in iron which initiates reaction of the soHd chlorate composite. Reaction of the cone material is started by a flash powder train fired by a spring-actuated hammer against a primer. An electrically heated wire has also been used. The candle is wrapped in insulation and held in an outer housing that is equipped with a gas exit port and rehef valve. Other elements of the assembly include gas-conditioning filters and chemicals and supports for vibration and shock resistance (4). 

The purity of oxygen from chlorate candles before and after gas filtration is indicated in Table 2. A particulate filter is always used. Filter chemicals are HopcaUte, which oxidizes CO to CO2 molecular sieves (qv), which remove chlorine compounds and basic materials, eg, soda lime, which removes CO2 and chlorine compounds. Other than H2O and N2, impurity levels of <1 ppm can be attained. Moisture can be reduced by using a desiccant (see Desiccants). Gas purity is a function of candle packaging as well as composition. A hotter burning unit, eg, one in which steel wool is the binder, generates more impurities. 

Operational Characteristics. Oxygen generation from chlorate candles is exothermic and management of the heat released is a function of design of the total unit iato which the candle is iacorporated. Because of the low heat content of the evolved gas, the gas exit temperature usually is less than ca 93°C. Some of the heat is taken up within the candle mass by specific heat or heat of fusion of the sodium chloride. The reacted candle mass continues to evolve heat after reaction ends. The heat release duting reaction is primarily a function of the fuel type and content, but averages 3.7 MJ/m (100 Btu/fT) of evolved oxygen at STP for 4—8 wt % iron compositions. 

The oxygen release rate is directly proportional to the cross-sectional area of the candle for a specific composition and also depends on the linear bum rate. Lower fuel contents decrease the bum rate slightly, eg, ca 2 wt % iron is the lower limit for rehable room temperature operation. Low temperature starts require at least 3.5 wt % iron. Another factor is direction of flow of the evolved gas. If the hot oxygen flows over the unbumed portion of the candle, as much as 15% rate iacreases can be produced. The bum time is halved for each 3.4 MPa (500 psi) pressure rise. The highest pressure that can be produced is ca 138 MPa (20,000 psi). 

Some PFBC boiler designs incorporate high-temperature, high-pressure (HTHP) filter devices in the flue-gas stream. These are installed primarily to protec t the gas turbine from erosion damage by the fine particles that escape the cyclones, but as the filters remove virtually all the suspended particulates, they also eliminate the need for back-end removal. The commonest HTHP filter elements used are rigid ceramic candles. 

Static sampling systems are defined as those that do not have an active air-moving component, such as the pump, to pull a sample to the collection medium. This type of sampling system has been used for over 100 years. Examples include the lead peroxide candle used to detect the presence of SO2 in the atmosphere and the dust-fall bucket and trays or slides coated with a viscous material used to detect particulate matter. This type of system suffers from inability to quantify the amount of pollutant present over a short period of time, i.e., less than 1 week. The potentially desirable characteristics of a static sampling system have led to further developments in this type of technology to provide quantitative information on pollutant concentrations over a fked period of time. Static sampling systems have been developed for use in the occupational environment and are also used to measure the exposure levels in the general community, e.g., radon gas in residences. 

Physical and Chemical Properties - Physical State at 15 Candl atm. Solid Molecular Weight Not pertinent Boiling Point at 1 atm. Very high Freezing Point 118 - 149, 48 - 65, 321 - 338 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 0.78-0.79 at 20°C (liquid) Vapor (Gas) Density Not pertinent Ratio cf Specific Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat of Combustion -18.000, -10.000, -430 Heat of Decomposition Not pertinent. 

The liquid, after passing through the outlet valve, joined the line from another filter that was in u.se. It is believed that carbon dioxide gas from the filter liquid passed up the outlet line into the filter that was being inspected (Figure 11-2). A test showed that contamination was not sufficient to prevent a candle burning. ... 

Lihou and Maund (1982) used soap bubbles filled with flammable gas which were blown on the bottom of a fireball chamber to form fireballs. A hemispherical bubble was formed on a wire mesh 200 mm above the base of the measuring chamber in order to permit study of elevated sources. The gas bubble was ignited by direct contact with a candle flame, and the combustion process was filmed at a speed of 64 frames per second. The fireball s color temperature was measured. 

Reiz-gas, n. irritant gas, Mil.) tear gas or sneeze gas. -geschoss, n. irritant gas projectile. -gift, n. irritant poison, -kerze, /. Mil.) irritant candle, -korper, m. irritant substance, Mil.) lacrimator. reizloa, a. nonirritant, nonatimulating unattractive, insipid. 

When a candle is burned, a gas is produced—a gas containing carbon dioxide and water vapor. It is useful to describe such a gas as a collection of molecules, each molecule containing smaller units called atoms. Each carbon dioxide molecule contains one carbon atom and two oxygen atoms. Each water molecule contains one oxygen atom and two hydrogen atoms. Where did these atoms come from Were they present in the candle before it burned ... 

Similar questions are raised if we consider the effect of cooling the gases produced from the candle. Cooling these gases results in condensation—drops of liquid water appear. If the water vapor contains molecules, made up of atoms, what happens to these molecules (and atoms) when the gas condenses Are they still present in the liquid ... 

A candle is burned under a beaker until it extinguishes itself. A sample of the gaseous mixture in the beaker contains 6.08 X 10 molecules of nitrogen, 0.76 X 1020 molecules of oxygen, and 0.50 X 10 molecules of carbon dioxide. The total pressure is 764 mm. What is the partial pressure of each gas ... 

The quantity consumed or produced is conveniently expressed in partial pressure units if the substance is a gas. Concentration units are convenient if the reactant or product is in solution. The time measurement is also expressed in whatever units fit the reaction microseconds for the explosion of household gas and oxygen, seconds or minutes for the burning of a candle, days for the rusting of iron, months for the rotting of wood. 

The chronology of the most remarkable contributions to combustion in the early stages of its development is as follows. In 1815, Sir Humphry Davy developed the miner s safety lamp. In 1826, Michael Faraday gave a series of lectures and wrote The Chemical History of Candle. In 1855, Robert Bunsen developed his premixed gas burner and measured flame temperatures and flame speed. Francois-Ernest Mallard and Emile Le Chatelier studied flame propagation and proposed the first flame structure theory in 1883. At the same time, the first evidence of detonation was discovered in 1879-1881 by Marcellin Berthelot and Paul Vieille this was immediately confirmed in 1881 by Mallard and Le Chatelier. In 1899-1905, David Chapman and Emile Jouguet developed the theory of deflagration and detonation and calculated the speed of detonation. In 1900, Paul Vieille provided the physical explanation of detonation... 

In the nineteenth century, Humphry Davy (1778-1829) speculated that the luminosity of flames is caused by fhe production and ignition of solid particles of carbon as a resulf of the decomposition of a part of the gas. Jons Jakob Berzelius (1779-1848) is said to be the first to describe an ordinary candle flame as consisting of four disfincf zones. Davy s protege, Michael Faraday [9] (1791-1867) gave his Christmas lectures and accom-pan3ung demonstrations to a juvenile audience on "The Chemical History of a Candle" in 1848 and 1860. Around the turn of the century, modem combustion science was established based on the increased understanding of chemistry, physics, and thermodynamics. 

Hot Gas Cleanup System Breakage of ceramic candle filters and stress corrosion cracking in heat exchangers has also been reported. 

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