Showing papers on "Rotary kiln published in 1988"

High efficiency gasifier with recycle system

Abstract: A high efficiency gasifier employs a rotary kiln having an indirect fired gasifier and a recycle system. The rotary kiln provides an essentially oxygen-free gasifying chamber into which raw feed material is introduced. Radiant tubes within the chamber transfer heat to the incoming raw feed material to pyrolyze it and convert it to char and product gas as the material advances toward the outlet end. The recycle system within the chamber returns both product gas and hot char to a receiving end of the kiln to aid in heat transfer to the raw feed material. The feed is thus heated more rapidly, and less heat input is required. Efficiency is further aided by providing additional residence time and gasification of the char.

Mechanisms governing transients from the batch incineration of liquid wastes in rotary kilns

Abstract: When "containerized" liquid wastes, bound on sorbents. are introduced into a rotary kiln in a batch mode, transient phenomena in-volving heat transfer into, and waste mass transfer out of, the sorbent can oromote the raoid release of waste vaoor into the kiln environment. This raoid vaoor release can cause depletion and displacement of the excess oxygen from the primary flame, and formation ofa "puff," which can result in a temporary Failure orthe incinerator system. Parametric studies on a specially designed rotary kiln incinerator simulator showed that puffs are easily generated even with very small quantities of surrogate wastes and at excess air values exceeding 100 percent. Furthermore, their magnitudes and intensities increase with increasing kiln temperature and kiln rotation speed. A theoretical model describing simultaneous heat and mass transfer through a sorbent aggregate, coupled with vapor pressure driven waste vaporization within the sorbent aggregate, was combined with a fragmcntau...

Method for recycle and use of contaminated soil and sludge

Abstract: Process for recycle and reuse of soil, sludge, sand, or rock containing: (a) at least about 16 wt % calcium oxide, about 5 wt % silica, about 1 wt % alumina, about 0.5 wt % Fe 2 O 3 , or about 0.76 wt % magnesia; and (b) at least about 5 ppm arsenic, about 100 ppm barium, about 1 ppm cadmium, about 5 ppm chromium, about 5 ppm lead, about 0.2 ppm mercury, about 1 ppm selenium, or about 5 ppm silver. The process comprising mixing the soil, sludge, sand, or rock with an amount of inorganic constituents to form a raw material mix having a chemical composition suitable for the manufacture of Portland cement, charging the slurry to a cement kiln, heating the slurry in the kiln to a temperature sufficient to form a cement clinker, and removing the cement clinker from the rotary kiln.

Method and apparatus for utilizing the heat energy of domestic and commercial refuse

Abstract: The invention relates to a method for utilizing the heat energy of domestic and commercial refuse in a rotary kiln installation. The prepared crude refuse is degassed in a pyrolysis reactor and the pyrolysis gas produced is delivered to the main burner of the rotary kiln, optionally using primary fuel. For optimum and economic production of the pyrolysis gas crushed refuse is dried pneumatically with the aid of exhaust air from the cooler and is delivered to the pyrolysis reactor. The pyrolysis reactor is heated indirectly to a low temperature with hot secondary air from the kiln outlet head and the pyrolysis gas produced is delivered together with used secondary air to the main burner of the kiln.

Method of controlling a rotary kiln during start-up

Abstract: To facilitate a smooth and quick start-up of a rotary kiln, a Fuzzy Logic Control system is proposed, the principal feature of which is to mandate control actions to decrease the specific heat consumption along a straight line from an initial high value to a steady-state value established for the kiln, and then to switch over to an existing steady-state fuzzy logic control mode. In the start-up phase, further process variables are preferably measured and monitored against reference values to mandate concurrent control actions influencing the Fuzzy Logic Control system in a weighted manner.

Method and apparatus for drying solid material

Abstract: A method for drying solids, such as bark, peat, wet coal or the like by means of waste heat recovered from a rotary kiln (1). Solids are dried by simultaneously utilizing both the radiation heat of the shell surface (18) of the rotary kiln and the heat of the hot flue gases being discharged from said rotary kiln. Solids are dried in a drying space (19), which is defined by the shell surface (18) of the rotary kiln and a jacket-like structure (17) surrounding at least part of the shell surface (18) of the rotary kiln (1). Flue gases from the rotary kiln are conducted together with solids through the drying space.

Method of processing contaminated mineral substances

Abstract: For the production of a product which can be dumped or utilized, the mineral substances are subjected in a rotary kiln to a thermal treatment at a temperature at which the charge of the rotary kiln is transformed to a pasty to liquid slag phase. The composition of the charge is so selected that a slag phase is produced in which the main components, which constitute a matrix, are in the range from 60 to 72% SiO 2 , 10 to 30% Al 2 O 3 and 5 to 25% CaO+MgO, of said matrix, wherein the total percentage of SiO 2 +Al 2 O 3 +CaO+MgO equals 100, the total of the main components SiO 2 , Al 2 O 3 , CaO and MgO amounts to more than 60% on a dry and ignition loss-free basis, of the mineral matter which is charged to the rotary kiln. The slag phase discharged from the rotary kiln is cooled and the exhaust gas from the rotary kiln is purified.

3-D Flow Modeling of a Hazardous Waste Incinerator

Abstract: A three-dimensional flow model of a hazardous waste incinerator kiln and vertical secondary combustion chamber arrangement was constructed to evaluate critical system parameters. The chamber wall configuration, location and arrangement of burners, and the positioning of the outlet duct were examined to determine the critical secondary combustion chamber gas residence time and mixing of the combustion flows. The scale model consisted of the rotary kiln as a primary combustion chamber, the secondary combustion chamber, two burners, and the exhaust ducting. Flue gas velocities in the model inlets and outlet were maintained to provide a Reynolds numbers equal to the full size unit. Patterns of smoke which were injected into the model inlets were viewed to evaluate flow mixing. Slow motion playback of video tape was used to determine the minimum residence time of flow in the high temperature combustion zone. The results of the model study were used to complete the engineering of a waste incineration system.

Apparatus for treating crude oil sludges and the like

Abstract: Crude oil sludges and other relatively heavy hydrocarbon liquid sludges are mixed with diatomaceous earth or perlite to form a friable and flowable solids mixture which is conveyed to a combustion unit, such as rotary kiln, calciner or lift pipe type combustor, wherein combustion of the hydrocarbons is carried out to provide gaseous combustion products and a substantially hydrocarbon free solids mixture. The solids discharged from the combustion unit may be recycled for use in the mixing process to reduce the sludge to a friable material for introduction to the combustion unit and excess solids may be discharged for disposal.

Production of metal oxide

Abstract: PURPOSE:To eliminate a remaining fluorine content without sintering a prepared metallic oxide, by calcining metallic fluoride complex crystal in a multi-column type rotary kiln of indirect heating type. CONSTITUTION:Metallic fluoride complex crystal is calcined in a multi-column type rotary kiln of indirect heating type. Fe, Ni, Cr, Ti, Cu, Zn and rare metal, etc., may be cited as the kind of the metal constituting the complex.

Process of making binderless briquets from steelworks dusts

Abstract: To produce smeltable briquets, steel-works dusts containing more that 15% metallic iron are heated in an indirectly heated rotary kiln to a briquetting temperature in excess of 500° C. under an atmosphere which is inert to the metallic iron. The heated dusts are briquetted in the briquetting roll press under an inert atmosphere and under a roll pressure from 60 to 150 kN/cm roll width. The hot briquets are separated from the fines under an inert atmosphere and are air-cooled to a temperature below 130° C. The fines are recycled to the rotary kiln.

Two dimensional modeling of waste combustion in a kiln

Abstract: A two dimensional model has been developed to model the incineration characteristics in a kiln. The specific configuration considered is a rotary kiln with two off-axis burners, one above the centerline and the other below it. In the two dimensional model the burners and the kiln are considered to be planar. The upper burner feed consists of carbon tetrachloride, methane and oxygen, while the lower burner feed is made up of methane and oxygen. Results are obtained both with and without a solid waste bed. The effect of the solid bed is incorporated through an empirically specified bed volatile release rate. The effect of kiln rotation is neglected. The governing conservation equations are solved by a control volume based finite difference procedure. The results are qualitatively compared with the measurements in a three dimensional kiln operating under similar conditions as the one in this study. In particular strong stratification of temperature and species concentration at the kiln exit is noted. This is validated by similar experimental observations.

Separation of carbon dioxide contained in exhaust gas and recovering method thereof

Abstract: PURPOSE:To efficiently recover high-purity carbon dioxide without largely modifying an existing installation by pressurizing exhaust gas subjected to dust removal and thereafter using a membrane for separating gas to selectively separate carbon dioxide and liquefying gaseous carbon dioxide. CONSTITUTION:In the case of installating a recovery equipment of gaseous carbon to a conventional lime kiln installation, both the exhaust gas of combustion gas generated from a rotary kiln 3 and the exhaust gas generated by decomposition of limestone are mixed and this mixture is sent to a dust collector 7 to remove dust and thereafter pressurized with a compressor 8. After subjecting this exhaust gas to temp. control in a cooler 9, gaseous carbon dioxide is selectively separated with a membrane 10 for separating gas. The separated gaseous carbon dioxide is liquefied wit the compressor 8 and a refrigerator 12 via a tank 11 of a crude gaseous carbon dioxide and highly purified in a purification tower 13 of gaseous carbon dioxide and filled into a tank 14 of liquid carbon dioxide.

Method and apparatus for smelting reduction

Abstract: PURPOSE:To effectively execute smelting reduction in a small-scaled equipment by introducing exhaust gas of a smelting reduction furnace to a dry type dust collector through a rotary kiln and a dryer, and bringing lump raw material into contact with the exhaust gas by counterflow from the dryer to the above kiln and furnace. CONSTITUTION:The exhaust gas A having high temp. exhausted from the smelting reduction furnace 1 is sent to the rotary kiln 2 by a suction fan 5, and brought into contact with the lump raw material B carried by counterflow to the exhaust gas A in the kiln 2, to preheat and prereduce the lump raw material B. In this way, the temp. of exhaust gas A flowed out from the kiln 2 is fallen, and the fallen temp. exhaust gas A is next sent to the dryer 3. The lump raw material with wet condition charged from charging hole 3a at downstream side of exhaust gas of the dryer 3, is carried by the counterflow to the exhaust gas A and brought into contact with the exhaust gas. In this way, as the exhaust gas A is further fallen, and flowed out from the dryer 3, the exhaust gas A can be treated in the ordinary dry type dust collector 4. Further, as the lump raw material carried from the kiln 2 to the furnace 1 is preheated and prereduced, the smelting reduction is effectively executed.

Calcining process and apparatus for black raw material vertical decomposition furnace

Abstract: The present invention concerns a concrete grog-calcining process for black raw material in a vertical decomposition furnace (VPBM process) In this process black raw material briquets are predecommposed in a specially designed vertical decomposition furnace, and then calcined in a rotary kiln to become concrete grog, the movement of the gas phase being countercurrent the solid phase The heat consumption of grog calcination of this process is 780-850 kilo-calories/Kg grogs, and the power consumption is also lower than that of common predecomposition kilns, showing that this process has the advantages of energy-saving, requiring less equipment and low investment It is widely adaptable to concrete plants of various production scales, from a daily production of 200-1000 tons and up It is also suitable for renovation of small sized hollow dry type revolving kilns and lipor kilns

Gas burner device of rotary kiln for reducing chromium ore

Abstract: PURPOSE:To effectively utilize hydrocarbon having high reducing power for reduction of chromium ore by installing a lance which bombards a gaseous fuel contg. the hydrocarbon to the raw material pellet layer in a rotary kiln to said rotary kiln separately from a main burner. CONSTITUTION:The lance 4 is provided separately from the main burner 2 at the time of heating and reducing the chromium ore pellet layer 3 in the rotary kiln 1. A coke oven gas 5 contg. the hydrocarbon and air 6 for combustion are supplied to the main burner 2 and only the coke oven gas 5 is supplied to the lance 4, by which said gas is bombarded to the pellet layer 3. The distribution ratio of the gas 5 is preferably adjusted to about 30-70% of the burner 2 side. The reducibility of the chromium ore pellets is thereby improved by about 5-10%.

Method for the production of cement clinker from semi-wet raw material

Abstract: The invention relates to a method and to apparatus for the production of cement clinker by the semi-wet process, in which a two-stage preheater supplied with additional fuel and a short rotary kiln are used and exhaust air from the cooler is delivered directly to the drying zone. In this way, even if the moisture content of the filter cake varies, it is possible to operate the kiln plant with a constant degree of deacidification and to ensure a stable kiln operation.

The Process Modeling and Simulations for the Fault Diagnosis of Rotary kiln Incineration Process

Abstract: This paper presents a rule-based and on-line expert system, named RKEXPERT, to supervise the combustion operations of a pilot scaled rotary kiln incinerator with a special focus on the fault diagnosis and feedback controls. The combustion process is routinely susceptible to a large number of operational problems. Knowledge base of RKEXPERT contains the heuristics and insights of experienced operators and also the knowledge necessary for problem solving related to diagnosis and control. The whole knowledge in this system was organized into a unique hierarchical structure and represented using an IF-THEN rule-based formation. Based on the rule-based expert system by on-line mode, the intelligent process operation aid system for the combustion plant was completed to provide integrity in optimal operation and control.

Heat treatment device for fines

Abstract: Die Erfindung betrifft eine Vorrichtung zur Warmebehandlung von feinkornigem Gut mit Drehrohrofen (4), Vorwarmer (1) und Brennkammer (2) zur Vorcalcination, wobei Kuhlerabluft (14) einerseits der Brennkammer und andererseits uber zwei Leitungen direkt der Ofenabgasleitung (15) zugefuhrt wird, wobei in diesen letzteren Leitungen kurz vor ihrer Einmundung in die Ofenabgasleitung (15) Anschlusse (17b, 17c) zur Zufuhrung von Brennstoff und vorgewarmten Gut vorgesehen sind. The invention relates to a device for heat treatment of fine-grained material with a rotary kiln (4), the preheater (1) and combustion chamber (2) for precalcination, wherein cooler exhaust air (14) of the kiln exhaust gas pipe (15) is supplied on the one hand the combustion chamber and on the other hand by two lines directly, where in these latter conduits shortly before its mouth into the kiln exhaust gas pipe (15) terminals (17b, 17c) are provided for supplying fuel and preheated Good.

Production of activated carbon

Abstract: PURPOSE:To produce the title activated carbon stably and easily and simultaneously to recover a useful activating exhaust gas by oxidizing coal in a rotary kiln to decrease the caking property, and then activating the coal in an external- heating rotary kiln. CONSTITUTION:The raw coal 1 is crushed, and the particle size is regulated. The coal is then introduced into the rotary kiln-type oxidation furnace 3, and oxidized to decrease the caking property. The coal is subsequently introduced into a carbonization furnace 4, heated at about 700 deg.C in an inert gaseous atmosphere, and carbonized. The obtained coal is introduced into the external-heating rotary kiln-type activation furnace 5, and activated at about 900 deg.C while blowing in an activating gas 6 such as steam or CO2. The obtained activated carbon 8 is cooled and recovered. The exhaust gas 15 generated by the activation reaction is introduced into sensible heat recovery device 9 wherein the sensible heat of the gas is recovered, and the components such as CO and H2 contained in the gas is efficiently utilized for producing chemical products and as fuel, etc.

Process and equipment for the manufacture of cement from moist raw materials

Abstract: In the manufacture of cement from moist raw materials, these are, according to known processes, fed directly to a wet rotary kiln immediately after prior wet grinding and fired therein to give clinker. In this case, all the slurry water must be evaporated, which involves a high consumption of thermal energy. In another process, a part of the raw materials is in turn prepared in the dry state, and the remaining part is subjected to wet grinding. After prior mixing and granulation, both part quantities are then fed to the rotary kiln. In this case, the relatively high equipment cost and the increased consumption of thermal energy are disadvantageous. According to the invention, however, these disadvantages are avoided by mixing the moist raw materials, before they are preheated and dried, with dry raw materials of substantially the same composition.

Method and device for operating rotary kiln for reducing chromium ore

Abstract: PURPOSE:To accelerate reduction of ore pellets and to prevent reoxidation by providing a suction fan near a drop part where the reduced pellets of chromium ore are discharged from a rotary kiln. CONSTITUTION:The reduced pellets 4 of the chromium ore formed by burning fuel in the rotary kiln 1 by a burner 2 are taken out via a chute 5 of a firing port hood 3 and are introduced into a cooler 30. The suction fan 7 for sucking the air in the hood 3 is provided near to the juncture between the hood 3 and the cooler 30 or to the cooler 30 side. The leakage of the air into the rotary film 1 or the suction of a large amt. of the vapor, etc., generated by the cooler 30 into the kiln 1 is thereby prevented and the high reducibility of the pellets 4 is maintained.

Manufacture of reduced chromium pellet

Abstract: PURPOSE:To manufacture a reduced chromium pellet of high reduction rate at a low cost, by charging a green pellet containing chromitite and reducing agent into a rotary kiln and then regulating air quantity and also controlling respective combustions in a reduction region and a preheating region. CONSTITUTION:A green pellet pelletized by using chromitite and an inner carbonaceous reducing agent is charged into a rotary kiln and subjected to reducing roasting in the presence of outer carbonaceous reducing agent by means the combustion of a burner. In a method for manufacturing the above-mentioned reduced chromium pellet, the combustion air quantity of the above burner is adjusted to 1-1.2 times the theoretical amount of air. Simultaneously, the rate of air inflow infiltrating from a tuyere is adjusted to <=20vol.% based on the above-mentioned theoretical amount of air so as to hold the pressure in the kiln negative. Further, the above outer carbonaceous reducing agent in an amount necessary for reducing the whole quantity of Co2 and O2 in a combustion gas existing in the undermentioned reduction region and excess air into CO gas is allowed to remain in a reduction region of 1,000-1,500 deg.C. On the other hand, air in an amount necessary for burning the whole amount of CO forming in the above-mentioned reduction region into CO2 is blown via an air inlet into a preheating region of 700-1,000 deg.C.

Method for transforming a rotary kiln intended in particular for the manufacture of cement, kiln obtained by this method and burning line equipped with this kiln

Abstract: The present invention concerns a method for transforming a rotary kiln equipped with a planetary cooler and intended in particular for the manufacture of cement, a kiln obtained by this method and a burning line equipped with this kiln, the kiln being constituted by an inclined rotary tube through which the material flows and which is heated inwardly, this tube comprising a downstream section constituting a burning zone having a smaller diameter than that of the upstream section constituting a material preparation zone, both sections being connected by a conical part, and the downstream section having a diameter comprised between 4 and 5,1 meters and a length comprised between 20 and 50 meters.

High temperature thermal treatment of contaminated soil

Abstract: Contaminated soil, abondoned waste disposal sites and polluted industrial sites from a major part of our environment requiring clean-up measures.

Trend display method for driving power of rotary kiln

Abstract: PURPOSE:To attain an operation system incorporating a CRT system by performing a trend display of the deflection width of the driving power of a rotary kiln on a CRT display in the same way as an analog meter. CONSTITUTION:The analog signal of the electric power of a rotary kiln driver 1 is converted into a digital signal by a computing element 2 containing an A/D converter. Then the maximum value is discriminated from the minimum value of the electric power for each rotation of the kiln and the digital signal is sent to a CRT control computer 3. The computer 3 plots both maximum and minimum levels of the electric power on the same axis in the vertical direction (vertical axis) for each unit time decided from the maximum and minimum value widths of the electric power. Then both levels are connected by a straight line and displayed on a CRT display 4 in the form of a vertical line.

Calcinator with two type of calcination

Abstract: The utility model discloses a calcinator with two calcinating modes used for calcinating carbon raw material. The calcinating mode of the existing calciner is single, a potting furnace and a rotary kiln can make use of the self-contained volatile matter thermal value of the raw material, the calcining temperature can only reach 1300 DEG C at most. The temperature of the electric calciner can reach 2000 DEG C, but the volatile matter in the raw material can not be used. The utility model combines the advantages of a potting furnace and an electric calciner in order to form a calcinator with two calcinating modes.