Overheating


The first reaction is exothermic, and the second is endothermic. Overall, the reaction evolves considerable heat. Figure 2.7 shows two alternative reactor designs. Figure 2.1a shows a shell and tube type of device which generates steam on the shell side. The temperature profile through the reactor in Fig. 2.7a is seen to be relatively smooth. Figure 2.76 shows an alternative reactor design that uses cold-shot cooling. By contrast with the tubular reactor, the cold-shot reactor shown in Fig. 2.76 experiences significant temperature fluctuations. Such fluctuations can cause accidental catalyst overheating and shorten catalyst life.  [c.56]

Finally, under the heading Specific pressure equipment requirements specific requirements are set out for equipment with a risk of overheating, for piping and, last but not least, specific quantitative requirements which set out a series of safety factors for certain pressure equipment. These latter provisions apply as a general rule which means that a manufacturer or a harmonised standard may deviate from these factors if it can be demonstrated that appropriate measures have been taken to achieve an equivalent level of safety.  [c.942]

Place in the flask 2 g. of benzophenone, 15 ml. of isopropanol and 2 5 g. of aluminium isopropoxide. This mixture has now to be heated gently under reflux so that the temperature registered by the thermometer in the column does not exceed 80°, i.e., so that only acetone distils. For this purpose, the flask should preferably be heated in an oil-bath direct heating, even over an asbestos sheet, may cause local overheating and decomposition the use of a water-bath on the other hand may make the column undesirably damp.  [c.154]

While the sodium ethoxide solution is cooling, prepare a solution of 7 7 g. of finely powdered iodine in 60 ml. of ether. When this solution is ready, add 9 ml. (9 6 g.) of ethyl malonate to the ethanolic sodium ethoxide solution, mix w ell and then allow to stand for 30-60 seconds not longer) then cautiously add the ethereal solution of the iodine, mixing thoroughly during the addition in order to avoid local overheating by the heat of the reaction. (If, after the ethyl malonate has been added to the sodium ethoxide, a considerable delay occurs before the iodine is added, the yield of the final product is markedly decreased.)  [c.276]

Now roll up the Carius tube (while still in a vertical position) in a strip of ordinary thick drying paper, and then place it in the heavy iron protector tube if the Carius tube is too short and tends to disappear within the iron tube, a short section of old glass tubing should first be placed in the iron tube so that the capillary of the Carius tube just projects. The function of the paper is to protect the Carius tubing from being scratched, and also (more important) to prevent the local overheating which would otherwise occur at places where the Carius tube is in direct contact with the iron tube. The sealed tube, throughout its manipulation, should be left as nearly vertical as possible, so that the contents do not leave the rounded end.  [c.420]

There are two main warning signs of a flash-back" which, if observed, allow sufficient time for remedial measures. During the combustion, the height of the pressure gauge fluctuates % ery little, but as soon as a flash-back, due to overheating, is imminent the pressure begins to rise. Immediately this is seen to occur the Bunsen should be moved back several cm. along the tube, and if the pressure still rises, right back to where heating was originally started.  [c.479]

Many students tend to forget the practical details learnt in elementary courses of chemistry they are therefore repeated here. To cut a piece of glass tubing, a deep scratch is first made with a triangular file or glass knife The tubing is held in both hands with the thumbs on either side of the scratch, but on the side opposite to it. The tubing is then pulled gently as though one wanted to stretch the tube and also open the scratch. A break with a clean edge will result. The cut edge must then be rounded or smoothed by fire polishing. The end of the tube is heated in the Bunsen fiame until the edges melt and become quite smooth the tube is steadily rotated aU the time so as to ensure even heating. Overheating should be avoided as the tube will then partially collapse.  [c.57]

Carbon disulphide. When working with this solvent, its toxicity (it is a blood and nerve poison) and particularly its high inflammability should be home in mind. Distillation of appreciable quantities of carbon disulphide should be carried out in a water bath at 55-65° it has been known to ignite from being overheated on a steam bath.  [c.175]

Preparation of the catalyst. Fill a hard glass e.g., Pyrex) tube, 100 cm. long and 1-5 cm. internal diameter, with pumice (4 8 mesh). Transfer the pumice into a thick suspension of about 40 g. of freshly precipitated manganous carbonate contained in a beaker. (The manganous carbonate is prepared by adding a solution of 38 g. A.R. anhydrous sodium carbonate to a solution of 70 g. of A.R. crystallised manganous chloride, and filtering). Heat the beaker on a hot plate with vigorous stirring with a glass rod until most of the water is expelled, then transfer the solid to a shallow porcelain basin and continue the heating, with stirring, until the lumps no longer cling together take great care to avoid local overheating. It is important to adjust the volume of water used in preparing the suspension of manganous carbonate so that most of the latter is absorbed by the pumice if much water has to be evaporated, the manganous carbonate does not adhere satisfactorily. When many preparations are to be carried out, it is advisable to prepare a larger quantity of the catalyst in one operation.  [c.339]

The element has a metallic, bright silver luster. It is relatively stable in air at room temperature, and is readily attacked and dissolved, with the evolution of hydrogen, but dilute and concentrated mineral acids. The metal is soft enough to be cut with a knife and can be machined without sparking if overheating is avoided. Small amounts of impurities can greatly affect its physical properties.  [c.191]

Place in the flask 2 g. of benzophenone, 15 ml. of isopropanol and 2-5 g. of aluminium isopropoxide. This mixture has now to be heated gently under reflux so that the temperature registered by the thermometer in the column does not exceed 80°, i.e., so that only acetone distils. For this purpose, the flask should preferably be heated in an oil-bath direct heating, even over an asbestos sheet, may cause local overheating and decomposition the use of a water-bath on the other hand may make the column undesirably damp.  [c.154]

While the sodium ethoxide solution is cooling, prepare a solution of 7-7 g. of finely powdered iodine in 60 ml. of ether. When this solution is ready, add 9 ml. (9-6 g.) of ethyl malonate to the ethanolic sodium ethoxide solution, mix well and then allow to stand for 30-60 seconds not longer) then cautiously add the ethereal solution of the iodine, mixing thoroughly during the addition in order to avoid local overheating by the heat of the reaction. (If, after the ethyl malonate has been added to the sodium ethoxide, a considerable delay occurs before the iodine is added, the yield of the final product is markedly decreased.)  [c.276]

Now roll up the Carius tube (while still in a vertical position) in a strip of ordinary thick drying-paper, and then place it in the heavy iron protector tube if the Carius tube is too short and tends to disappear within the iron tube, a short section of old glass tubing should first be placed in the iron tube so that the capillary of the Carius tube just projects. The function of the paper is to protect the Carius tubing from being scratched, and also (more important) to prevent the local overheating which would otherwise occur at places where the Carius tube is in direct contact with the iron tube. The sealed tube, throughout its manipulation, should be left as nearly vertical as possible, so that the contents do not leave the rounded end.  [c.420]

There are two main warning signs of a flash-back which, if observed, allow sufficient time for remedial measures. During the combustion, the height of the pressure gauge fluctuates very little, but as soon as a flash-back, due to overheating, is imminent the pressure begins to rise. Immediately this is seen to occur the Bunsen should be moved back several cm. along the tube, and if the pressure still rises, right back to where heating was originally started.  [c.479]

Industrial use of thermal imaging typically is the detection of thermal anomaUes (13,14) such as leaking pipes and valves, overheating boilers, transformers and power lines, and friction generated heat in bearings. A thermal image of a transformer station is shown in Figure 7. These are simple heat detection appHcations but the imaging process quickly locates the problem in the three-dimensional industrial environment. The in camera is scanned like a TV camera and the output signal is digitized for evaluation by a programmed computer than compares the output of each frame with a caUbrated reference frame. An alarm declares when a thermal anomaly is detected. Defects in materials (15) and circuit boards (16) can be detected by the associated discontinuities in thermal conduction.  [c.294]

Oxidation. Aluminum alkyls are oxidised to the corresponding alkoxides using dry air above atmospheric pressure in a fast, highly exothermic reaction. In general, a solvent is used to help avoid localised overheating and to decrease the viscosity of the solution. By-products include paraffins, aldehydes, ketones, olefins, esters, and alcohols accidental introduction of moisture increases paraffin formation. To prevent contamination, solvent and by-products must be removed before hydrolysis. Removal can be effected by high temperature vacuum flashing or by stripping.  [c.456]

Drying (qv) is accompHshed in a rotary dmm-type dryer, usually gas fired. Diammonium phosphate becomes unstable at relatively low temperatures care must be taken to avoid overheating. For this reason, cocurrent drying is the preferred mode and product discharge temperature is not allowed to exceed about 88°C. Normally, the screening operation is carried out hot, and only the product-size fraction is cooled. Cooling is carried out by contact with air in either a rotary dmm or a fluidized bed. Cooling to about 50°C is considered desirable to avoid caking in bulk storage. Particle size of the granular product, as produced in the United States, normally is within the range of 1 to 3.5 mm particle diameter. An average diameter is about 2.3 mm. Moisture content is 1 to 2%. Normally, no granule coating or other anticaking treatment is necessary. Iron, aluminum, and other impurities derived from the wet-process feed acid exert sufficient hardening and anticaking effect (35).  [c.229]

Under normal processing conditions at 300—350°C, Tefzel resins are not subject to autocatalytic degradation. However, extended overheating can result in "blow-backs" through extmder feed hopper or barrel front.  [c.370]

Aluminum bromide and chloride are equally active catalysts, whereas boron trifluoride is considerably less active probably because of its limited solubiUty in aromatic hydrocarbons. The perchloryl aromatics are interesting compounds but must be handled with care because of their explosive nature and sensitivity to mechanical shock and local overheating.  [c.561]

There are additional problems in making the electrical connections to the work to be heated. The connection must have low electrical resistance to prevent overheating at the point of contact, but such a connection has a low resistance to heat transfer, thus conducting heat away from the work. These problems have limited the use of direct-resistance heating mainly to heating of pipe, tubing, bars, or small identical parts. This heating is a one-piece-at-a-time batch operation and often does not use an insulated housing instead it is used as a preheater for a forming operation that takes place as soon as the work reaches the desired temperature.  [c.138]

Octane. Octane is probably the single most recognized measure of gasoline quaUty. The octane value of gasolines are posted on service station dispensers, and most drivers recognize a fuel in which the octane is too low. Broadly speaking, octane is a measure of the combustion characteristics of gasoline. In an Otto cycle engine, gasoline vapor in the combustion chamber must start to bum only when the spark plug ignites after the charge has been compressed. Then it must bum with a weU-defined flame front that travels all the way across the combustion chamber. Low octane gasoline has a tendency to preignite. As the flame front sweeps across the combustion chamber, the unbumed portion of the fuel (end gas) heats up under rapidly rising temperature and pressure conditions. The fuel—air mixture undergoes chemical reactions which may cause it to autoignite and detonate the entire remaining mixture. Instead of being pushed down smoothly on the power stroke, the piston is given a hard instantaneous rap to which it caimot respond because of the large mechanical inertia present in the crankshaft and other pistons. This rapid energy release causes pressure fluctuations in the cylinder which result in a loud metallic noise commonly called knock. In addition to producing an objectionable sound, knock reduces the amount of useful work that can be extracted from the engine. Power is dissipated in the pressure waves and increased heat is radiated to the cylinder walls and into the cooling water. Under extreme conditions of prolonged knock, overheating and even engine damage can occur. The damage is typically caused by catastrophic melting of piston crowns or head gaskets.  [c.179]

A rotary stirrer driven by an induction motor housed within the vessel was an integral part of the ICI process. Eigure 28 shows a general arrangement of the 250 L autoclave introduced in 1943 in which the stirrer motor housing was coupled to the reaction vessel, both being designed for the same pressure. The shaft from the motor passed through the stem connecting the two components and was coupled to the stirrer (not shown), which extended over the length of the reaction space. Cool ethylene entered the top of the motor housing and passed through the gap between the rotor and stator down the stem containing the shaft into the reaction space. Development of a satisfactory stirrer involved extensive flow visualization and mathematical modeling from an engineering point of view, many of the early problems stemmed from decompositions caused by local overheating or breakage of stirrer bearings.  [c.97]

In addition to these mechanical problems there are two aspects of the compression process which relate specifically to ethylene. Eirst, there is a tendency for small amounts of low molecular weight polymer to be formed and, second, the gas may decompose into carbon, hydrogen, and methane if it becomes overheated during compression. Cavities in which the gas can collect and form polymer, which hardens with time or in which the gas can become hot, need to be avoided.  [c.100]

Dry Generator. This water-to-carbide acetylene generation method is used in certain large-scale operations. The dry process uses about a kg of water per kg of carbide and the heat of reaction is dissipated by the vaporization of the water. Absolute control of the addition of water is critical and the reacting mass of dry lime and unreacted carbide must be continuously mixed to prevent hazardous localized overheating and formation of undesirable polymer by-products. The gas stream is filtered to remove lime dust. The dry lime by-product is considered to be advantageous compared to the wet lime by-product. Time from dry generators is very fine and requires storage in silos or protection from scattering by wind currents. Transport must be in closed containers, such as bags.  [c.380]

HBI is used as a trim coolant or scrap replacement in oxygen steelmaking. In the oxygen steelmaking process, the molten steel often is overheated. Trim coolant is fed to the furnace to cool the molten steel to the desired temperature. HBI is preferred for this appHcation because its high density ensures an effective slag penetration and complete melting in the molten steel bath. Steel yield is increased when HBI is used as a trim coolant instead of iron ore. Also, the violent reactions that can occur when using iron ore are eliminated. The relative cooling effect of various materials are as follows scrap 1.0, HBI 1.2, and iron ore 2.0—3.0.  [c.432]

Place 90 ml. of 30% aqueous potassium hydroxide and 60 ml. of acetone in the flask. Weigh out 17 g. of sodium, cut it into small lumps or strips, and store these in a short wide-necked corked bottle for protection from the atmosphere. Now add the sodium, withdrawn one piece at a time with tongs or a pointed glass rod, to the mixture the sodium floats on the upper layer of acetone as it reacts. Occasionally swirl the mixture gently around, taking great care that the sodium does not come in contact with the lower solution of potash, otherwise local overheating and charring will occur, (If the sodium should stick in the condenser during the addition, push it down with a glass rod having at its upper end either a right-angle bend, or a cork firmly affixed, so that the lower end of the rod can project only just beyond the bottom of the condenser if it slips from the fingers, it cannot therefore smash the base of the flask.)  [c.149]

Add 2 g. of anthracene and 1 g. maleic anhydride to 25 ml. of dry xylene, and boil the mixture under reflux during the early stages of the heating, keep the mixture gently shaken until a clear solution is obtained, otherwise a portion of the reagents may adhere to the base of the flask and darken because of local overheating. After boiling for 20 minutes, cool the solution, when the addition product will rapidly crystallise. Filter at the pump, and drain well. (Yield of crude material, which is almost pure, ca, 2-7 g.) Recrystallise from about 50 ml. of xylene with the addition if necessary of a small quantity of animal charcoal filter the solution through a small preheated funnel, as the solute rapidly crystallises as the solution begins to cool. Place the recrys-  [c.292]

The rate at which bubbles of gas enter the nitrometer is now determined solely by the rate at which the heating is carried out it should be controlled so as never to exceed one bubble of gas per second. The oxidised copper spiral is carefully heated to redness by very slowly moving the burner along it, and the heating of the powder copper oxide, containing the washings from the mixing tube, is then started. Up to this point, any gas that enters the nitrometer will be carbon dioxide, and even while heating the initial portion of copper oxide, the amount of nitrogeneous material contained in it is so small that very little nitrogen will be evolved. As the burner approaches the first chalk mark, however, extra care is required as very nearly all the sample is contained in this small section of tube filling, and overheating will cause rapid combustion with a consequent rapid stream of gas bubbles in the nitrometer. The great danger here is that these bubbles contain ing both nitrogen and carbon dioxide may rise rapidly through the potash and a considerable proportion of the constituent carbon dioxide will then never be absorbed by the alkali, thus leading to high results. Nearly all the errors made in nitrogen determinations arise from this source and the importance of a slow, regular evolution of gas controlled by careful combustion, cannot be overstressed. As soon as there is any sign of too rapid an evolution of gas the burner should immediately be moved 5 cm. back along the tube rapidity of this movement is particularly important as there is usually a time lag between any overheating and the emergence of the offending bubbles in the nitrometer. Heating is continued until the burner arrives at the furnace mouth. The burner may then be extinguished.  [c.490]

Anhydrous sodium acetate. Crystallised sodium acetate, CHjCOONa. 3HjO, is heated in a casserole or in a shallow iron or nickel dish over a small free flame. The salt first liquefies, steam is evolved and the mass solidifies as soon as most of the water of crystallisation has been driven off. To remove the residual water, the solid is carefully heated with a larger flame, the burner being constantly moved until the solid just melts. Care must be taken that the solid is not overheated too strong heating will be recognised by the evolution of combustible gases and charring of the substance. The fused salt is allowed to solidify, and is removed from the vessel whilst still warm with a knife or other convenient object. It is immediately powdered and stored in a tightly stoppered bottle.  [c.197]

An electric heating mantle may also be used temperatures up to about 400° C. are readily attained, it can be employed with highly inflammable liquids and bumping is largel eliminated. The construction of a typical electric heating mantle will be apparent from Fig. II, 57, 1, in which it surrounds a single neck flask with a thermometer or sight well. The heating element (nichrome or equivalent resistance wire) is embedded in layers of glass fabric near the exposed surface and is further covered by layers of glass wool insulation. The two hemispherical halves are held together by a Zip fastener or by glass fibre cords. The temperature lag is small since the heating elements are very close to the flask wall. A built-in thermo couple is available in certain types so that the internal temperature can be read with a suitable pyrometer a small thermostat may also be embedded in the heating elements to prevent overheating. Special supports (cradles) for the heating mantles are marketed.  [c.222]

Place 90 ml. of 30 /0 aqueous potassium hydroxide and 60 ml. of acetone in the flask. Weigh out 17 g. of sodium, cut it into small lumps or strips, and store these in a short wide-necked corked bottle for protection from the atmosphere. Now add the sodium, withdrawn one piece at a time with tongs or a pointed glass rod, to the mixture the sodium floats on the upper layer of acetone as it reacts. Occasionally swirl the mixture gently around, taking great care that the sodium does not come in contact with the lower solution of potash, otherwise local overheating and charring will occur. (If the sodium should stick in the condenser during the addition, push it down with a glass rod having at its upper end either a right-angle bend, or a cork firmly affixed, so that the lower end of the rod can project only just beyond the bottom of the condenser if it slips from the fingers, it cannot therefore smash the base of the flask.)  [c.149]

Add 2 g. of anthracene and 1 g. maleic anhydride to 25 ml. of dry xylene, and boil the mixture under reflux during the early stages of the heating, keep the mixture gently shaken until a clear solution is obtained, otherwise a portion of the reagents may adhere to the base of the flask and darken because of local overheating. After boiling for 20 minutes, cool the solution, when the addition product will rapidly crystallise. Filter at the pump, and drain well. (Yield of crude material, which is almost pure, ca. 2 7 g.) Recrystallise from about 50 ml. of xylene with the addition if necessary of a small quantity of animal charcoal filter the solution through a small preheated funnel, as the solute rapidly crystallises as the solution begins to cool. Place the recrys-  [c.292]

The rate at which bubbles of gas enter the nitrometer is now determined solely by the rate at which the heating is carried out it should be controlled so as never to exceed one bubble of gas per second. The Oxidised copper spiral is carefully heated to redness by very slowly moving the burner along it, and the heating of the powder copper oxide, containing the washings from the mixing tube, is then started. Up to this point, any gas that enters the nitrometer will be carbon dioxide, and even while heating the initial portion of copper oxide, the amount of nitrogeneous material contained in it is so small that very little nitrogen will be evolved. As the burner approaches the first chalk mark, however, extra care is required as very nearly all the sample is contained in this small section of tube filling, and overheating will cause rapid combustion with a consequent rapid stream of gas bubbles in the nitrometer. The great danger here is that these bubbles containing both nitrogen and carbon dioxide may rise rapidly through the potash and a considerable proportion of the constituent carbon dioxide will then never be absorbed by the alkali, thus leading to high results. Nearly all the errors made in nitrogen determinations arise from this source and the importance of a slow, regular evolution of gas controlled by careful combustion, cannot be overstressed. As soon as there is any sign of too rapid an evolution of gas the burner should immediately be moved 5 cm. back along the tube rapidity of this movement is particularly important as there is usually a time lag between any overheating and the emergence of the offending bubbles in the nitrometer. Heating is continued until the burner arrives at the furnace mouth. The burner may then be extinguished.  [c.490]

The mixed acid and glycerol are metered iato the nitrator, quickly submerged, emulsified, and forced up the nitrator past the cooling cods. Part of the nitroglycerin overflows iato the separator, and part returns to the vortex ia the nitrator fluid. The temperature is kept at 10—20°C. The emulsified mixture of nitroglycerin and spent acid enters the acid separator where a slight rotating action imparted to the upper layer of the Hquid breaks the emulsion and prevents overheating. The spent acid flows continuously through an overflow from the bottom of the acid separator to its storage tank. The nitroglycerin may also be separated ia a specially designed centrifuge. The remaining acid is neutralized, and the product washed with water until it passes the specification test for stabiHty. The Biazzi process is also used for the manufacture of other nitrate esters such as triethylene glycol dinitrate, butanetriol trinitrate, and trim ethyl o1 eth an e trinitrate (metriol trinitrate).  [c.12]

In starting a fan, the air power increases gradually with speed which is a desirable starting load. However, in large heavy fans considerable torque is required to overcome the fan wheel inertia (referred to as WR, where W is the mass of the wheel and shaft and R is the radius of gyration). Figure 8 illustrates typical fan wheel and motor torques as a function of system speed during the starting process. Fan torque is that required for overcoming wheel inertia and for mnning power for the speed attained. Motor torque at every point on the starting curve must be greater than fan torque. The vertical difference shown in Figure 8 is the torque available for acceleration. If the motor is started across the line and the length of time required to reach full load is too long (usually 10 s is desirable), the motor may become overheated and overload controls shut off the power. Thus the fan cannot be started. On long power lines, the innish of starting current may also drop line voltage sufficiently so that fan and motor are too slow in coming up to speed. Alternatively, reduced-voltage starters can be used, which permit extended starting periods without motor overheating, or special motors with winding that can be bypassed during starting can be used. In calculating the starting time of a fan (13), in addition to the WR of the fan wheel, the flywheel effect of large drive sheaves and the motor rotor itself must also be included.  [c.108]

PCTFE plastics can be processed by the standard thermoplastic fabrication techniques, eg, extmsion, injection, compression, and transfer mol ding. Specific corrosion-resistant alloys or chrome or nickel plating are recommended for equipment parts in contact with the polymer melt, such as molds, barrels, screws, etc (see Pplastics technology). The control of processing temperatures is paramount since prolonged overheating (above 260°C) can result in degradation of the polymer causing discoloration, voids, bUsters, and loss of properties. The plastic can be easily machined from billets or rod stock on standard machining equipment to fabricate more precise part geometries, but sharp tools should be employed.  [c.394]

Defects such as hot tears or laps, quench cracks, localized overheating during stress rehef, and corrosion may occur during the tubemaking process (154). Magnetic particle, ultrasonic, and visual inspection techniques are used to ensure that relatively few tubes enter service with significant defects.  [c.96]

Because of the exothermic reaction and the evolution of gas, the most important safety considerations in the design of acetylene generators are the avoidance of excessively high temperatures and high pressures. The heat of reaction must be dissipated rapidly and efficiently in order to avoid local overheating of the calcium carbide which, in the absence of sufficient water, may become incandescent and cause progressive decomposition of the acetylene and the development of explosive pressures. Maintaining temperatures less than 150°C also minimi2es polymeri2ation of acetylene and other side reactions which may form undesirable contaminants. For protection against high pressures, industrial acetylene generators are equipped with pressure rehef devices which do not allow the pressure to exceed 204.7 kPa (15 psig). This pressure is commonly accepted as a safe upper limit for operating the generator.  [c.379]

Water-to-Garbide Generation. This method of acetylene production has found only limited acceptance in the United States and Canada but has been used frequently in Europe for small-scale generation. The rate of generation is regulated by the rate of water flow to the carbide. Ha2ardous hot spots may occur and overheating may lead to the formation of undesirable polymer by-products. This method is, therefore, used mainly in small acetylene generators such as portable lights or lamps where the generation rate is slow and the mass of carbide is small.  [c.380]

The vegetable-tanning materials are commercially extracted using hot water. The extraction is normally done in countercurrent extractors that permit the final removal of the extracts with fresh water. The dilute extracts are then evaporated to the desired concentration in multiple effect evaporators. Some extracts may be further dried by spray drying or any other means that proves effective without overheating the extract. Extract preparation depends on the type of extract, the si2e of the operation, and the desired concentration of the final product.  [c.86]

Storage. Concern about spontaneous ignition has led some operators to try to match the mining and consumption rates, so that there is Httie if any reserve, as in minemouth power generation stations. When the coal must be stockpiled, careful stacking minimi2es oxygen reaction and overheating. Uniform stacking in layers no more than 0.3 m thick avoids segregation of particle si2es, then compacting using earth-moving equipment, and covering the pile with finer material limits oxygen penetration, overheating, and ignition. By sloping (14°) the sides gradually, segregation is prevented and compaction is improved (30).  [c.154]


See pages that mention the term Overheating : [c.2923]    [c.507]    [c.54]    [c.507]    [c.362]    [c.7]    [c.389]    [c.59]    [c.229]    [c.400]   
What went wrong (0) -- [ c.207 , c.225 , c.226 , c.375 ]