Showing papers on "Spontaneous combustion published in 1981"

Plasma jet ignition system for internal combustion engine

Abstract: A plasma jet ignition system for an internal combustion engine has a plasma jet spark plug which receives ignition energy from two energy sources, one for a spark ignition and the other for a plasma jet ignition, and performs a plasma jet ignition as well as a spark ignition. There are further provided various control circuits to control the ignition energy to reduce energy consumption and to promote the functions of the plasma jet ignition. One of these circuits is arranged to stop the plasma jet ignition during a cranking period while cranking is continued after duration of a plasma jet ignition for a predetermined time period. Another control circuit is arranged to control the plasma jet ignition energy corresponding to the engine temperature.

Combustion control by prestratification

Abstract: Combustion control in a spark ignited internal combustion engine for inhibition of incipient detonation, or knock, is provided by the addition of exhaust gases or other diluent gases to the intake manifold of the engine prior to opening of the intake valve. The addition of this diluent gas causes a prestratification of the charge entering the combustion chamber of the engine. Upon compression and ignition of the charge, the diluent gas inhibits spontaneous combustion of the portions of the charge furthest away from the site of ignition of the charge, thereby preventing one cause of incipient detonation. This combustion control may be used with turbocharged and supercharged engines, as well as with naturally aspirated internal combustion engines, and allows the engine to operate on much lower octane fuel than would be possible without prestratification.

Reduction of spontaneous combustion of coal

Abstract: A composition for the prevention of spontaneous combustion of coal is described which is comprised of at least about 2 percent of polyethylene oxide and the balance water. Also described is a method for reducing the spontaneous combustion tendency of coal by contacting coal with the above composition and then drying the coal.

A Study on Ignition and Combustion of a Diesel Spray by Means of a Rapid Compression Machine

Abstract: A free-piston type rapid compression machine has been developed to simulate combustion process occurring in a diesel engine A light piston is pneumatically shot and gets hammered in a stop ring at the compression end A satisfactory performance has been achieved by this device, permitting a near-constant elevated pressure and temperature sufficient to explore ignition of a fuel spray and the subsequent combustion From a series of tests carried out on this machine, it has been shown that the ignition lag exhibits little or small dependence on pressure and temperature at some elevated pressures and temperatures It has been also pointed out that in the so-called diffusive burning period, combustion proceeds with self-accelerating rate of heat release in the case when much fuel is allotted to this period, while the rate declines monotonically with time in the contrary case

Catalytic activation of a charge in a prechamber of a si lean-burn engine

Abstract: A new concept for lean combustion has been proposed. The concept involves a subdivided combustion chamber configuration coupled with catalytic activation of a charge prior to ignition by means of a catalyst located inside the prechamber. A complex program was conducted using three experimental set-ups: a combustion bomb, a single compression machine and a small real SI engine. The effect of the subdivided combustion chamber geometry on the combustion process was investigated and the influence of the catalyst was determined. It has been concluded that the chemical activation of a charge prior to ignition due to the presence of the catalyst in the prechamber facilitates ignition, shortens the ignition delay and strengthens the flame kernel in its initial development phase. The presence of the catalyst in the engine prechamber resulted in the extention of the misfire limit and a significant reduction in cycle-to-cycle variations in pressure profiles. The investigations have confirmed that improvement of a combustion process is made possible by a change in the combustion chemistry.

The spontaneous decomposition, oxidation and ignition of ethylene oxide under rapid compression

Abstract: Conditions for the spontaneous ignition of ethylene oxide vapour were explored in circumstances where it experiences compression, and heating due to it. Experiments were carried out on dilute mixtures of ethylene oxide in argon, and on systems containing varying amounts of added oxygen, using a rapid compression apparatus of proven performance. Total initial pressures were varied from 13 to 50 kN m −2 and the compression ratio from ca. 10:1 to ca. 12:1. Pressure-time histories were measured, and gas temperatures assessed from them. Emitted light intensities were recorded and overall compositions were measured by mass spectrometry. Overall product compositions for the pyrolysis and oxidation of ethylene oxide are given. Decomposition occurs rapidly at temperatures of about 850 K and its exothermicity exceeds 100 kJ mol −1 . (By contrast, acetaldehyde pyrolysis is almost thermoneutral and it occurs only at temperatures in excess of 1000 K.) Ignition of ethylene oxide is possible in the mixtures 1 C 2 H 4 O+20 Ar when compression is more than 11-fold. A typical ignition delay is 5 ms. Trace amounts of added oxygen enhance the reaction rate and the extent of self-heating due to it. With roughly equal amounts of ethylene oxide and oxygen, ignition occurs in circumstances where none would be possible in its absence, and the delay interval is short (

Spontaneous combustion in beds of small fuel particles

Abstract: The spontaneous combustion of beds of finely divided carbonaceopus material is of interest in several areas of power station operation and especially in coal milling, where the self heating of pulverised fuel deposits may lead to fires. This paper describes, an experimental technique for determining the susceptibility of various coals to spontaneous combustion and also shows that a simple approximation to the temperature profiles in, the bed can be used to extrapolate the results to plant-scale dimensions with sufficient accuracy for practical purposes. The simple model is first shown to agree adequately with the classical Frank-Kamenetskii, and more exact numerical, solutions for the cases of slab, cylindrical and spherical beds, and then with finite difference solutions for a rectangular prism. Measurements of ‘onset,’ where spontaneous heating is first detected, and ‘critical’ temperatures for, beds of pulverized coal heated in an oven, show the same variation with the bed depth as the model and can thus be fitted and extrapolated by suitable choice of activation energy. The neglect in deriving the model of any element of oxygen starvation or convective heat transfer within the bed is seen to be only partly justified under all sub-critical, conditions, but the effect at onset is not measurable. Wide variations in critical temperature have been observed over the range of bituminous coals so far examined.

Ethanol combustion diesel engine with light oil as ignition fuel

Abstract: PURPOSE:To improve ignition performance, by firstly injecting light oil into a combustion chamber near the top dead center of compression stroke to ignite the light oil and then injecting a large quantity of ethanol into the light oil ignition area to cause the diesel combustion of the ethanol. CONSTITUTION:At the stroke of compression, a piston 1 goes up, the temperature of spontaneous ignition falls and the temperature of air rises. When the temperature of a previous combustion chamber 6 exceeds the that of spontaneous ignition near the end of the dead center of the compression stroke, a small quantity of light oil is injected into the chamber 6 through an injection valve 10 to ignite a mixture of medium concentration between excessive thickness and excessive thinness. A large quantity of ethanol is injected from an ethanol injection nozzle 12 toward the combustion flame of the light oil and right then burned. The pressure of the previous combustion chamber 6 sharply rises due to the flame of the thanol and exceeds that of a main combustion chamber 4. The nucleus of the flame in the previous combustion chamber 6 rushes together with unburned constituents and an excessively thick mixture into the main combustion chamber 4 through an injection port 5. The exces sively thick mixture is mixed with an excessively thin mixture in the chamber 4 so that the excessively thick mixture is diluted.

Combustion Reaction Mechanisms from Ignition Delay Times

Abstract: Ignition studies behind reflected shock waves in a single pulse shock tube are described for three combustion systems: 1. C2N2+O2→CO+N2 2. COS+O2→CO+SO2 3. COS+2N2O→CO+SO2+N2

Preventing method for ignition of urethane foam during polymerization-maturing

Abstract: PURPOSE:To prevent and extinguish spontaneous combustion rapidly and poaitively by a minimum amount of a fire-extinguishing agent by a method wherein internal ignition is detected by the concentration of gas generated by an abnormal reaction, a fire on an outer surface is detected by ignition and an inert gas is discharged. CONSTITUTION:As to the ignition prevention resulting from an internal abnormal reaction, an alarm device 3 is actuated by signals S1 when the concentration of gas to be measured of a semiconductor type gas detector 1 reaches 100-200ppm, and a pre-alarm is given. Thus, a counter-measure is taken which pulls out a foaming body outside a warehouse, but a carbonic acid gas discharging driving device 4 is actuated by signals S2 when the internal abnormal reaction makes rapid progress and the concentration of gas generated rises before taking a proper counter-measure and reaches approximate 200-600ppm, and carbonic acid gas 5 is discharged into a maturing warehouse by the function of a prolonging discharging system 6. As to an external fire, the alarm device 3 is worked through signals S3 by the functioning of a fire sensor 2, while the device 4 is operated by signals S4 and one section of the carbonic acid gas 5 is discharged inside the warehouse according to a short-time discharging system 7.

Storage method for coal

Abstract: PURPOSE:To prevent coal from spontaneous ignition in a coal-storage installation by providing a nitrogen producer in the neighborhood and ventilating the coal-storage installation with the nitrogen produced by this producer. CONSTITUTION:The gas in a coal-storage tank 1 is subjected to continuous sampling and measured in its density of CO by a CO-meter 2. When this density of CO reaches to a critical value previously set, a valve 4 is opened by a valve-operation controller 3, and nitrogen is supplied into the tank 1 from a nitrogen tank 5. When the density of CO is brought under the set value, the valve 4 is closed. The nitrogen is produced by a nitrogen concentrator 6 such as a T.O. or a P.S.A. plant, and accumulated in the tank 5. In this construction, since the air in a coal-storage installation is replaced with the nitrogen concentrated from the air to restrain the oxidizing reaction of coal, the coal can be surely prevented from spontaneous ignition.

Degradation and spontaneous ignition studies of brominated polyphenylquinoxalines

Abstract: The thermal and thermal-oxidative degradations, and spontaneous ignition of brominated polyphenylquinoxalines (PPQ) have been examined. The bromine insertions into the macro-chain have been found to reduce the rate of oxidation, especially at high temperatures.