Showing papers on "Coke published in 1989"
TL;DR: In this paper, the modes of coking and deactivation of zeolites during n-heptane cracking at 723 K were established on the basis of the composition of the carbonaceous compounds responsible for deactivation (coke), the deactivating effect of the coke molecules and reduction by coke of the volume accessible to nitrogen and to n-hexane.
582 citations
TL;DR: In this paper, the homogeneous vapor phase cracking of newly formed wood pyrolysis tar was studied at low molar concentrations as a function of temperature (773 - 1.073 K), at residence times of 0.9 - 2.2 s.
Abstract: The homogeneous vapor phase cracking of newly formed wood pyrolysis tar was studied at low molar concentrations as a function of temperature (773 - 1.073 K), at residence times of 0.9 - 2.2 s. Tar conversions ranged from about 5 to 88%. The tars were generated by low heating rate (0.2 K/s) pyrolysis of --2 cm deep beds of sweet gum hardwood, and then rapidly conveyed to an adjacent reactor for controlled thermal treatment. Quantitative yields and kinetics were obtained for tar cracking and resulting product formation. The major tar conversion product was carbon monoxide, which accounted for over two-thirds of the tar lost at high severities. Corresponding ethylene and methane yields were each about 10% of the converted tar. Coke formation was negligible and weight-average tar molecular weight declined with increasing tar conversion.
336 citations
TL;DR: In this article, a four-lump model is proposed to describe the process of fluid catalytic cracking in which the deposition rate of coke on catalyst can be predicted from gas oil conversion and isolated from the C 1 − 4 gas yield.
Abstract: In the fluid catalytic cracking reactor heavy gas oil is cracked into more valuable lighter hydrocarbon products. The reactor input is a mixture of hydrocarbons which makes the reaction kinetics very complicated due to the involved reactions. In this paper, a four-lump model is proposed to describe the process. This model is different from others mainly in that the deposition rate of coke on catalyst can be predicted from gas oil conversion and isolated from the C1–C4 gas yield. This is important since coke supplies heat required for endothermic reactions occurring in the reactor. By this model we can also conclude that the C1–C4 gas yield increases with increasing reactor temperature, while production of gasoline and coke decreases.
149 citations
Patent•
03 Aug 1989TL;DR: In this article, a municipal sanitary sewage sludge is disposed of by an improved partial oxidation process without polluting the environment, where aqueous slurries are upgraded by hydrothermal treatment, preferably while being sheared, concentrated, and then mixed with a supplemental fuel.
Abstract: Municipal sanitary sewage sludge is disposed of by an improved partial oxidation process without polluting the environment. Aqueous slurries of sewage sludge are upgraded by hydrothermal treatment, preferably while being sheared, concentrated, and then mixed with a supplemental fuel, preferably coal. A pumpable aqueous slurry of sewage sludge-coal and/or petroleum coke is thereby produced having a greater total solids and heat content (HHV) as well as containing an increased amount of sewage sludge for reacting with free-oxygen containing gas in a free-flow partial oxidation gas generator. Hot quench water or steam produced by cooling the hot raw effluent stream of synthesis gas, reducing gas or fuel gas from the gasifier may provide heat for the hydrothermal step.
128 citations
TL;DR: In this paper, the deactivation of H-mordenite and ZrO2/SO2−4 was investigated in the isomerization of n-butane.
83 citations
TL;DR: In this paper, four kinetic models for catalytic cracking of gasoline are proposed based on catalytic and catalyst deactivation models presented in the literature, and experiments for estimating the parameters of the models were performed in a bench-scale fixed bed reactor.
Abstract: Four kinetic models for catalytic cracking of gasoline are proposed based on catalytic cracking and catalyst deactivation models presented in the literature. In three of them, it is assumed that activity decayed with catalyst time-on-stream; in the last model, the decay in activity was related to the amount of coke deposited on the catalyst. Experiments for estimating the parameters of the models were performed in a bench-scale fixed bed reactor. One of the kinetic models was selected as the one that best describes the catalytic cracking of gasoline. The selected model was further incorporated into a gas oil range paraffinic compounds cracking model, which also had its parameters estimated. Finally, some coke-on-catalyst profiles along the axial direction of a fixed bed reactor during the catalytic cracking of gas oil range paraffinic compounds are predicted.
58 citations
TL;DR: In this article, optical microscopy allied with an image analysis system has been shown to provide the means of obtaining reliable and representative measurements of parameters characterizing this macroporosity, and the results obtained by this method have been used to relate the effects of differences in the coke porous structure on coke strength and to a lesser extent on the reactivity to CO2.
55 citations
TL;DR: In this article, the presence of water seems to decrease the destructive effect of low-temperature oxidation considerably, while all other conditions are held constant, there is a sharp decrease in the amount of tetrahydrofuran solubles and coke formed, with a consequent decrease in both the viscosity and acidity of the produced oil.
Abstract: When low-temperature oxidation (LTO) occurs, it causes undesirable changes in both the physical properties and the chemical composition of heavy oil. The presence of water, however, seems to decrease the destructive effect of LTO considerably. When LTO is carried out in the presence of water, while all other conditions are held constant, there is a sharp decrease in the amount of tetrahydrofuran solubles and coke formed. Furthermore, liberation of carbon dioxide, with a consequent decrease in both the viscosity and acidity of the produced oil, is much greater in the presence of water
49 citations
TL;DR: Carbonaceous deposits (coke) formed on zeolites H-ZSM-5 and Linde L during methanol conversion at 460°C have been studied with transmission electron microscopy (TEM) as discussed by the authors.
46 citations
Patent•
30 Jan 1989TL;DR: In this paper, high water content sludges are used to quench the coke during the quench phase of the coking cycle, with minimal increases in coke volatile matter.
Abstract: Petroleum refinery waste stream sludges are recycled by segregating the sludges according to their oil content. Sludges of high oil content are developed and then injected into a delayed coking unit during the coking phase so that they are converted to coke and liquid coking products. High water content sludges are used to quench the coke during the quench phase of the coking cycle, with minimal increases in coke volatile matter. The process increases the capacity of the delayed coking unit to process and recycle refinery waste sludges and produce a coke of lower volatile content.
45 citations
Patent•
30 Jan 1989
TL;DR: In this paper, the authors proposed a method to maintain the stable conditions of a blast furnace by detecting the distribution of the amount of carbon consumed by a deposition reaction and the distribution by a gasification reaction from the concn. distributions of CO, CO2 and H2.
Abstract: PURPOSE:To maintain the stable conditions of a blast furnace by detecting the distribution of the amount of carbon consumed by a deposition reaction and the distribution of the amount of carbon consumed by a gasification reaction from the concn. distributions of CO, CO2 and H2 in the longitudinal direction of the furnace, and regulating the ore/coke distribution in accordance with said carbon amount distributions. CONSTITUTION:Gas in a blast furnace is continuously collected in the longitudinal direction of the furnace at several positions in the radial direction of the furnace, and by analyzing the gas, the concn. distributions of CO, CO2 and H2 in the longitudinal direction are detected. The distribution of the amount of carbon consumed by a deposition reaction and the distribution of the amount of carbon consumed by a gasification reaction in the longitudinal direction are calculated from the concn. distributions. In accordance with the carbon amount distributions, the ore/coke distribution is regulated so as to reduce the amount of carbon to be consumed by the deposition reaction in an upper part of the furnace and to reduce the amount of carbon to be consumed by the gasification reaction in a lower part of the furnace.
TL;DR: In this article, the effect of steam on the coking of Pt/Al2O3 was studied at 400°C under atmospheric pressure in the presence of cyclopentane in dry or wet (0.67 kPa of water) nitrogen.
TL;DR: In this paper, the formation of coke in methanol and ethylene reaction over two well-characterized industrial H-ZSM-5-based catalysts was studied mainly by UV-visible spectroscopy.
Abstract: Coke formation upon methanol and ethylene reaction over two well-characterized industrial H-ZSM-5-based catalysts was studied mainly by UV-visible spectroscopy. The investigations were complemented by TGA/GC determination of the H/C ratio of the carbonaceous deposits as well as by in-situ IR and conversion measurements. Various stages of coke formation as a function of reaction temperature, catalyst acidity and morphology were distinguished and correlated to catalytic performance.
TL;DR: In this article, the pre-ignition permeability of granulated sinter feed was examined using a conventional permeameter and a small instrumented sinter pot, respectively.
Abstract: Raw mixes of iron ore sinter feed were prepared under a variety of conditions. The permeability of mixes before ignition and during sintering was examined using a conventional permeameter and a small instrumented sinter pot, respectively. The sinter pot consisted of a gas preheater and a sample bed 29 mm high so that pressure drop of high temperature zones could be measured precisely and easily.As expected, the pre-ignition permeability of the mixes was related to the mean size of the granules which in turn was related to the amount of water used for granulating. The order of permeability of mixes having different moisture contents did not change during or after sintering. Late-addition of coke during granulation resulted in a higher pre-ignition permeability. During sintering, however, the permeability deteriorated considerably. Use of lager particles of coke or limestone resulted in improved permeability before and during sintering. The basicity and coke content of mixes had little effect on the permeability of a bed during and after sintering under the condition of constant total amount of flux (SiO2+CaO).It was concluded that the permeability of the produced sinter cake depended predominantly on the pre-ignition permeability, for mixes of the same ore type and the same total amount of flux. This suggests that some aspect of the structure of a bed of granulated sinter feed is preserved during sintering.
TL;DR: In this article, a mechanism of puffing that occurs during graphitization of needle coke in the electrode is proposed based on the experimental results in the literature, and procedures for puffing inhibition are suggested.
TL;DR: In this paper, the location and structure of carbonaceous deposits formed upon coking Pt Al 2 O 3 catalysts with cyclopentane have been studied by conventional TEM and by electron energy loss spectroscopy (EELS) associated with high resolution scanning transmission electron microscopy.
TL;DR: In this article, a 0.30 m diameter atmospheric pressure gasifier operated as either a fluidized or a spouted bed was used to extract coke from two Alberta oil sands operations.
TL;DR: In this article, a sample of ZSM-5 catalysts which had been used for converting methanol to hydrocarbons in a test reactor were examined by sorption measurements and Trimethylamine was used to assess the available pore volume and total number of acid sites.
Patent•
20 Mar 1989TL;DR: In this article, a petroleum refinery process for the production of alkyl aromatic hydrocarbons from a C 4 - fuel gas containing light olefins including ethene and propene and catalytic reformate containing C 6 to C 8 aromatics is described.
Abstract: A petroleum refinery process for the production of alkyl aromatic hydrocarbons from a C 4 - fuel gas containing light olefins including ethene and propene and catalytic reformate containing C 6 to C 8 aromatics. The C 4 - fuel gas is contacted with the catalytic reformate at a weight ratio of aromatics to olefins of 10:1 to 15:1 over a zeolite catalyst under process conditions to alkylate the C 6 to C 8 aromatics, particularly benzene, in the reformate with ethene and propene in the C 4 - fuel gas to form alkyl aromatic hydrocarbons. The reaction is carried out in a riser reactor having multiple olefin feed injection points in the riser section of the reactor. The catalytic reaction also causes the conversion of a small amount of light olefins in the fuel gas to coke by-product and the deposition of coke on the catalyst. The deposited coke causes the partial deactivation of the catalyst. A portion of the partially deactivated catalyst is continuously or intermittently withdrawn from the riser reactor and regenerated in a catalyst regenerator by contacting the catalyst with hydrogen containing regeneration gas or by contacting the catalyst with an oxygen containing regeneration gas to remove substantially all of the coke from the catalyst. The regenerated catalyst is introduced in the riser reactor and contacted with fresh feed.
TL;DR: In this paper, the authors evaluated the activation energy and reaction order with respect to oxygen for the coke burning of a Pt Re/Al 2 O 3 naphtha reforming catalyst.
Patent•
20 Nov 1989
TL;DR: An improved process for vaporizing a crude petroleum feedstock, preferably one boiling in the vacuum gas oil range or higher, prior to thermal cracking to olefins, wherein such feedstock is preheated, in one or more stages, in the convection section of a tubular steam cracking furnace, characterized by conducting the preheating in the presence of a small amount of hydrogen, preferably at a hydrogen/feed ratio of from about 0.01 to about 0.15 wt %, so as to inhibit coke formation.
Abstract: An improved process for vaporizing a crude petroleum feedstock, preferably one boiling in the vacuum gas oil range or higher, prior to thermal cracking to olefins, wherein such feedstock is preheated, in one or more stages, in the convection section of a tubular steam cracking furnace, characterized by conducting the preheating in the presence of a small amount of hydrogen, preferably at a hydrogen/feed ratio of from about 0.01 to about 0.15 wt. %, so as to inhibit coke formation.
TL;DR: In this article, three different models for describing a fluidized-bed catalyst cracking regenerator are studied, namely the grid-effect, two-region and bubbling-bed models, with the proposed two thermally uniform stages to account for the heat balance.
Patent•
23 May 1989
TL;DR: In this article, an electric arc is used for reacting carbonaceous materials and water to produce a combustible gaseous product comprising hydrogen, carbon monoxide and methane, which is used to react carbonaceous material and water.
Abstract: An electric arc is used for reacting carbonaceous materials and water to produce a combustible gaseous product comprising hydrogen, carbon monoxide and methane. Apparatus for carrying out said method comprises a primary reactor including means (30) positioned at the top of the chamber for maintaining a constant volume level of carbonaceous material in the chamber, a pair of electrodes (17, 19) at the bottom of the chamber for creating an electric arc zone of sufficient intensity to electrothermally and photochemically activate gasification of the carbonaceous materials, and a water reservoir (11) disposed below the electric arc zone; a secondary reactor including therein a coke bed (63) and electrode (53) extending through the top of the chamber and spaced from the coke bed for creating an electric arc therewith, and an electrode (65) at the bottom of the chamber in electrical connection with the coke bed.
TL;DR: In this article, a coked naphtha reforming catalyst was tested with several model hydrocarbons (n-hexane, n-heptane and a mixture of n-pentane and cyclohexane) to determine the contributions of catalytic functions.
TL;DR: In this article, the authors evaluated the qualities of coke lumps produced in a tube bomb in terms of their CTE and anisotropic development and found that the cocarbonization of a Fluidized Catalytic Cracking decant oil (FCCDO) with a petroleum low sulfur vacuum residue (LSVR) was studied at a temperature range of 460 to 480°C.
TL;DR: In this paper, a range of catalysts were screened for activity and product selectivities in the pyrolysis of methane, and experiments were performed in a flow reactor at 1125 °C and atmospheric pressure.
Patent•
09 May 1989
TL;DR: In this article, methods for inhibiting coke formation in pyrolytic reactors and furnaces are disclosed wherein effective alkaline earth metal salt coke retardant treatments are used.
Abstract: Methods for inhibiting coke formation in pyrolytic reactors and furnaces are disclosed wherein effective alkaline earth metal salt coke retardant treatments are used. Exemplary coke retardant treatments include magnesium and calcium salts such as the acetate, chloride, and nitrate, and magnesium sulfate salt.
Patent•
30 Nov 1989
TL;DR: In this article, surface-active substances such as activated charcoals, brown coal open-hearth coke, activated aluminium oxide and silica gel are additionally added in finely divided form to the water required for slaking burnt lime.
Abstract: Surface-active substances such as activated charcoals, brown coal open-hearth coke, activated aluminium oxide and silica gel are additionally added in finely divided form to the water required for slaking burnt lime. A Ca(OH)2 is obtained which is particularly suitable for separating off Hg from gases and exhaust gases. In addition, residual contents of HCl, SO2 and nitrogen oxides can further be separated off. It is also possible to add the surface-active substances to the burnt lime prior to slaking or to the Ca(OH)2. The surface-active substances can be impinged with catalytically active heavy metals, e.g. vanadium, or with substances binding heavy metals, e.g. sodium sulphide. The surface-active substances used are activated charcoals, brown coal open-hearth coke, silica gel, kieselguhr and/or activated aluminium oxide.
TL;DR: In this article, the specific contributions made by DTA and DSC are reviewed and the value/applications of this approach established, within this context the specific contribution made by the DTA approach and the specific applications of the approach are established.
Abstract: With petroleum reserves limited, and nuclear sources increasingly unacceptable, the use of coal (and potentially oil shale) is rapidly increasing as is its content of inorganics (minerals). Thermal analysis techniques are particularly suited for the evaluation, characterisation, analysis, basic, applied and pollution research of such organic and inorganic fossil fuel materials. The type, composition, quality and thermal decomposition characteristics of which control the calorific value, volatile yield, petrochemical potential, coke and fly ash derivatives together with end product ash. slag and gases such as hydrocarbons, SOx, NOx and CO2. Within this context the specific contributions made by DTA and DSC are reviewed and the value/applications of this approach established.
Patent•
23 Jun 1989
TL;DR: In this paper, a carbon graphite material consisting of aggregate and a binding material is formed by bonding particles of aggregate through graphite layers derived from a binder having two or more different graphitizing properties.
Abstract: PURPOSE:To form a carbon graphite material having small coefficient of thermal expansion and low modulus of elasticity, high thermal conductivity, strength, density and electrical conductivity, by bonding particles of aggregate through carbon graphite layers having two or more graphitizing properties. CONSTITUTION:This carbon graphite material consists of aggregate and a binding material and the aggregate is bonded through carbon graphite layers derived from a binder having two or more different graphitizing properties. Raw coke, mesocarbon beads, calcined coke, carbon black, artificial or natural graphite may be cited as the aggregate. The shape of the aggregate may be granular, porous, flat, short fiber state, filamentous, woven fabric, etc. Pitch, thermoplastic resin or thermosetting resin is used as the binder. An alternate laminate of a thermoplastic binder and a thermoplastic binder is preferable.