PRODUCTS FROM FLASH PYROLYSIS OF A TURKISH LIGNITE IN A FREE-FALL REACTOR UNDER VACUUM

Flash pyrolysis of a Turkish lignite under vacuum in a free-fall reactor was examined at a temperature range of 400 - 800 °C. Gaseous products were analysed with an on-line GC equipped with a manuel injection valve. Solvent fractionation was applied to the liquid product to separate preasphaltenes, asphaltenes and oils fractions. Two particle distributions of the lignite were used: -0.315+0.2 mm and -0.1 mm. The liquid yield increased with temperature up to 650 °C and, thereafter decreased for the larger particles. The maximum liquid yield, excluding pyroltic water, was found to be 8 % wt (dal) at 650 °C. In the case of the smaller particles the liquid yield increased steadily with temperature and the yield of liquid, excluding pyrolytic water, was 5.9 % wt (da) at 850 °C. The gaseous product yield also increased with temperature for both size fractions, and CO and CO₂ in the gaseous products were present in large amounts.     

Hydrothermal treatment of electron-beam irradiated pine sawdust in a mixture with vacuum tower bottoms

Hydrothermal processing of electron-beam irradiated pine sawdust in a mixture with vacuum tower bottoms (VTB) in an autoclave with continuous removal of the vapor phase at a hydrogen pressure of 7.0 MPa has been investigated. It has been found that as the sawdust irradiation dose increases to 1.0 MGy, the degree of VTB conversion during the hydrothermal treatment of the mixture increases and the amount of the hydrocarbon fraction in the resulting liquid product grows to reach a yield of 38.0 wt %. At a temperature of 430°C, the conversion of biomass for two hours is 83–84 wt % and the yields of liquid and gaseous products are 49.0 and 35.0 wt %, respectively.     

LIQUEFACTION OF BEYPAZARI LIGNITE USING NiCl2-KCl-LiCl CATALYSTS. 1. DIFFERENCE IN SOLID AND MOLTEN SALT CATALYSIS

ABSTRACT

Liquefaction of Beypazan lignite in tetralin using NiCl₂-KCl-LiCl (14:36:50 molar percentages) as catalyst was investigated. Effects of the catalyst/lignite ratio and temperature were determined in experiments done at 275°C, 300°C and 360°C. Liquid products were separated into oils, asphaltenes and asphaltols by a solvent extraction method. Yield of liquefaction increased with temperature in all experiments, the highest yield was observed in experiments performed at the eutectic temperature of the catalyst mixture. The highest yields of oils were 20% and 30% with a catalyst/coal ratio of 0.5 at 275°C and 300°C, respectively. The activity of the catalyst increased in experiments in which the catalyst was molten. The yield of asphaltenes were not affected with increases in the catalyst/coal ratio in the experiments done at 275°C or 300°C in which the catalyst mixtures were in solid state. Asphaltene yields decreased from 25% to less than 5% with increasing values of catalyst/coal ratio and the asphaltol yields remained constant at 10% between catalyst/coal ratios of 0.25 and 1.00 and suddenly increased to 30% and 40% for catalyst/coal ratios of 1.50 and 2.00, respectively, at 360°C. The molecular weights of the oils decreased from 340 to a minimum value of 245 as the catalyst/coal ratio was increased from 0 to 1.00 in experiments done at 360°C where the catalyst was molten. As the catalyst/coal ratio was further increased from 1.00 to 2.00 the molecular weight increased to 310.It seemed that the N1Cl₂-KCl-LiCl catalyst mixture in all catalyst/coal ratios was more efficient in molten phase than it was used as a solid mixture.     

LIQUEFACTION AND THE CHARACTERIZATION OF COAL DERIVED LIQUIDS OF MENGEN LIGNITE

ABSTRACT

The liquefaction characteristics of Mengen lignite has been investigated in the presence of cobalt-molybdenum on alumina catalyst in a 1 lt batch autoclave system with anthracene oil used as solvent. The experiments were carried out in the range of 15–60 atm for initial hydrogen pressure, 360–440°C for reaction temperature, 1–5 for solvent to coal ratio and 0–20% of coal for catalyst loading which were chosen as process variables. Coal particle size and reaction time were kept constant as below 200 mesh and 30 minutes respectively, (Erdem 1987)

The product was analyzed in terms of total conversion, liquid yield and liquid product distribution determined as preasphaltenes, asphaltenes and oils. The oil fraction was further separated by column chromatography while the asphaltenes were separated into basic and acid/neutral fractions. The preasphaltenes were divided into two fractions as carbene (CS₂ solubles) and carboid (CS₂ insolubles). (Inanç 1989)

The oil yield is mostly affected by the catalyst loading which shows to a certain extent that the conversion of asphaltenes to oils is a catalytic step. The selected process variables showed a positive trend with respect to the yield of hexane eluted oil which is the desired product of liquefaction.     

PRODUCTION OF HIGH QUALITY LIQUID FUELS FROM COAL BY MILD PYROLYSIS OF COAL-LIME MIXTURES

Abstract

The most recent studies of coal devolatilization processes have emphasized maximisation of liquids yield by use of extreme process conditions such as high heating rate. The liquids produced by such processes are often unsuitable for utilization without extensive upgrading. The aim of the study reported here was to optimize product quality by use of relatively mild conditions. Low-temperature devolatilization (slow heating to 500° to 650°C in a batch reactor) of coal in the presence of CaO (10 to 20 weight percent) can produce a relatively high-quality liquid fuel (containing low sulfur, low oxygen, low viscosity, low Conradson carbon residue, and low pour point). Compared to that occurring in rapid heat-up processes, the residence time of both the liquid and gaseous products is significantly greater in a batch or fixed-bed slow-heating system. It is proposed that this increased residence time facilitates greater secondary reactions of the primary products in the coal bed with the added CaO. The H/C (atomic) ratio of the liquids generated in such a relatively simple devolatilization system can vary between 1.3 and 1.5 for high-volatile coals such as Illinois No. 6 or Pittsburgh No. 8. The presence of CaO in the fuel bed markedly reduces H₂S in the gas phase and decreases sulfur and oxygen heteroatoms in the liquids.     

RAPID PYROLYSIS OF EASTERN CANADIAN COALS BY FREE FALL REACTORS

Abstract

The effect of temperature was investigated on the rapid pyrolysis of Prince, Lingan and No. 26 coals in the temperature range of 525^° to 750^°C using a 600 cm high stainless-steel free fall reactor at atmospheric pressure.

The yields of char, condensibles and gaseous products were determined at 25^°C intervals. Gaseous products were analysed for H₂, CO, CO₂, CH₄ and C₂+.

Volatile product (condensible and gas) yields exceeded the volatile product in the A.S.T.M. methods at and above 700^°C.

Some experiments using Prince coal were repeated at reduced pressure (50 mm mercury) in both the 600 cm height stainless-steel and a 140 cm height quartz reactor in order to find out the effect of pressure and retention time.

The experimental results indicated that the condensable yield was higher at the lower pressure and at the shorter retention time. The effect of retention time was far more pronounced.     

Characterization of Thermally Degraded Asphaltene Fractions Using Gel Permeation Chromatography

Abstract

Petroleum asphaltene goes through three stages of mass reduction under thermogravimetric analysis from 25°C to 1,000°C at a heating rate of 1°C/min. The products from thermal degradation of asphaltene at three different temperature intervals are collected. Two residual fractions left in the sample cup are also obtained at two specific temperatures. The collected fractions and the residual fractions are characterized using gel permeation chromatography. The fraction collected between 25°C and 350°C demonstrates similar molecular weight distribution to that collected between 350°C and 450°C, with both fractions showing a typical molecular weight distribution for polymeric material. The fraction collected between 450°C and 650°C illustrates three different molecular weight distributions. The chromatogram of the residual fraction obtained at 350°C resembles that of the undegraded asphaltene. The residual fraction obtained at 450°C also demonstrates three different molecular weight distributions. The experimental data indicate that the mass reduction of asphaltene heated from 25°C to 350°C is mainly due to the evaporation of low boiling point and/or low molecular weight substances in asphaltene. Thermal decomposition and coke production occur significantly in the 350°C–450°C temperature interval. Thermal degradation continues to finish until 650°C.     

HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

ABSTRACT

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal–derived slurry oil at 90 bar initial pressure for temperatures of 380–460^° C and residence time of 15–60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂–pressure of 60–150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂–pressure of 90–150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂–pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

PYROLYSIS OF SOME TURKISH LIGNITES BETWEEN 200 - 600°C

Abstract

This study was undertaken to examine the effect of pyrolysis between 200-600°C on sulphur content, proximate and ultimate analyses of four (Seyitomer, Tuncbilck, Elbistan and Kangal) lignite samples. A decrease in semi-coke yield and an increase in tar and gas yields with increasing temperature were observed for all samples. Percent reduction of volatile matter was the same up to 400°C for the lignites. It has been observed that total sulphur contents were reduced significantly during carbonization. The highest sulphur reduction, 45%, was obtained with Elbistan lignite. By increasing temperature, hydrogen, carbon dioxide, methane and hydrogen sulphur yields increased notably but ethane and propane yields increased only slightly for all samples. In order to study effect of C, H and O contents of the original lignites on the yield and the distribution of the products, a linear regression analysis has been carried out and the model relations have been obtained. Experimental data and the model values from the relations have been compared. Yield values appear to be in good agreement with the model values for all samples.     

A Thermal Simulation of the Influence of Volcanic Fluids on Source Rock

In the Songliao Basin, Cretaceous Yingcheng volcanic rock is an important natural gas reservoir. Volcanic rocks and source rocks interspersed in the fault depressions represent ideal places for studying the interactions between volcanic fluids and source rock. Thermal simulations for this study include the dry system and the fluid system. The characteristics of the gas yield and gas composition were analyzed under four temperature gradients: 300°C, 350°C, 400°C, and 450°C. The results of the experiment showed that in both systems, the gas yield increases with an increase in temperature. The gas compositions are similar, containing H₂, CO, CO₂, and gaseous C₁-C₅ hydrocarbons. Compared with the dry system, the gas yield of the volcanic fluid to mudstone system has a critical temperature between 350°C and 450°C. When the temperature is below the critical temperature, the gas yield increases, and vice versa. The generation of CO₂ is promoted by the volcanic fluids, but the generation of H₂ and C₁–C₅ series gaseous hydrocarbons is simultaneously restrained. In the fluid system, the content of H₂ and gaseous C₁–C₅ hydrocarbons is lower, but CO₂ content is greater than in the dry system. This can explain the fact that a huge amount of CO₂ gas is present as a reservoir in the Songliao Basin.     

Energy Optimization Design of ARFCC Process for Reducing Gasoline Olefin

Abstract

In view of the high energy consumption inherent in the auxiliary riser fluid catalytic cracking (ARFCC) process, a new energy optimization design has been suggested in this paper to decrease its auxiliary system energy cost and improve its product quality. The heat distribution of an auxiliary fractional system has been optimized and its surplus heat was used to heat crude gasoline, making low-temperature liquid crude gasoline into gas, which was then fed into the auxiliary reactor. The application in an ARFCC unit with 75 t/h of crude gasoline to be reprocessed showed, after the energy optimization design, that when the crude gasoline feed was heated from 40°C to 219°C, the contact temperature difference between the feed and the regenerated catalyst reduced from 650°C to 322°C, process exergy loss decreased by 77.8%, and less dry gas and coke was formed in the auxiliary reactor. At the same time, the energy-use optimization of the auxiliary fractional system increased its exergy recovery efficiency by 25%, 9.73 GJ/hr more valid heat was recovered, and 23.5 t/h more medium pressure steam was produced by the heat of the regenerated catalyst replaced by gaseous crude gasoline. The total energy consumption of the ARFCC process was reduced by a 6.8 kgEO/t feed.     

STEAM GASIFICATION OF BALMER COAL IN THE PRESENCE OF LIGNITE ASH

ABSTRACT

Steam gasification of blends prepared from Balraer coal and the ash from combustion of Onakawana lignite was performed in a fixed bed reactor. The blends were prepared by co-slurrying followed by drying. In the presence of 20 wt % ash the gasification rate doubled at 830° and 930°C. Direct blending of coal and lignite resulted In an overall increase in carbon conversion at 830°C but had no effect at 930°C.     

Thermal Degradation of Asphaltene and Infrared Characterization of Its Degraded Fractions

Abstract

Petroleum asphaltene and its thermally degraded fractions are characterized using thermal analysis and infrared spectrometry, respectively. Thermal analysis of asphaltene has demonstrated that heating rate is important in studying thermal degradation of asphaltene. Asphaltene goes through three stages of mass reduction under thermogravimetric analysis from 25 to 1,000°C at a heating rate of 1°C/min and below. The products from thermal degradation of asphaltene at three different temperature intervals are collected. The collected fractions are characterized using a Fourier transform infrared spectrometer. The fraction collected between 220 and 350°C demonstrates similar infrared spectrum to that of asphaltene, however, with less aromatic properties. The fraction collected between 350 and 450°C resembles the undegraded asphaltene most based on the infrared spectra obtained. The fraction collected between 450 and 650°C demonstrates a spectrum that is totally different from those of the undegraded asphaltene and the other two fractions. In addition, a high degree of oxidation is observed on all of the three degraded fractions of asphaltene.     

Catalytic co-cracking of waste polypropylene and residual fuel oil

Abstract

Industrial waste polypropylene (PP) homopolymer and residual fuel oil (RFO) were pyrolyzed together in presence of catalyst ZSM-5 under the atmospheric pressure with different mixing ratios of the feedstocks. The experiments were carried out in a batch reactor at two different temperatures of 500?°C and 600?°C with the blended mixture (PP/RFO) to catalyst (ZSM-5) ratio of 4:1. The effects of blending ratios between the two feedstocks and temperature with respect to the yield of the products oil, gas, and residual coke were determined. The optimum blending ratio of PP and RFO with respect the higher quantity yield of liquid product was found to be 1:1 at 500?°C. The percentages of liquid fuel, gas, and coke were observed to be 74.8%, 10.2%, and 15% at 500?°C.     

Performance-focused Catalyst Design to Meet Diesel Quality Improvements—Part II

Abstract

In this work, we present an experimental evaluation concerning the catalytic hydrocracking of gas oil (GO) feedstock. The study was carried out using five types of supported NiMo-based catalysts (100A, 100AP, 100AB, 100H-DY, and 30H-DY). Screening tests of the performance of these sulfided catalysts were carried out in a high-pressure batch autoclave at temperatures of 350°C–425°C, reaction time of 1–3 hr, catalyst/feed ratios of 5–10%, and initial hydrogen pressure of 6.0 MPa. This study clearly shows that the incorporation of H-DY zolite into aluminum borate (AB) matrix led to a greatly improved hydrocracking catalyst for production of lighter products, in addition to depressing the pour point of the diesel fuel product. In all experiments, the yield of gasoline and gaseous products increased dramatically by increasing the severity of the process variables. A high-pressure test unit was used to study the effect of different process variables as pressure (3.0–6.0 MPa), liquid hourly space velocity (1.5–3 hr^?1), hydrogen/ GO volumetric ratio (400 vol./vol.), and temperatures of 375°C, on the GO conversion to various products using 30H-DY catalyst, and to correlate the impact of process conditions on the yield and quality of diesel fuel and gasoline products to optimize the process     

Alkylating activity of an Omnikat-210P zeolite catalyst modified with Ni,Cr, and Co

An Omnikat-210P zeolite catalyst modified with Ni, Cr, and Co in a total amount of 4.53 wt % has been synthesized. X-ray diffraction analysis of the catalyst has been conducted; the oxide content of the original and modified catalyst has been determined. The dependence of the liquid yield on reaction temperature, contact time, and feed space velocity has been revealed. It has been found that the reaction products comprise 49.1 wt % isoparaffins and 41.3 wt % aromatics with no olefin hydrocarbons. The boiling range of the liquid products is 27.9–253.7°C. The octane number of the liquid products is on the order of RON 90.7.     

HYDROZEN TRANSFER HYDROCRAKING OF C.PROCERA UNDER AMBIENT PRESSURE CONDITIONS TO GET VALUE ADDED CHEMICALS AND FUELS

ABSTRACT

Biomass is renewable source of energy while the reserves of petroleum arc being depleted. The latex of a potential petrocrop, Colotropis procera, a lalicifcr, arid-plant which is rich in hydrocarbon type triterpene compounds etc. was found lo be a better feed slock for thermal hydrocracking as compared to whole plant biomass inlcrms of liquid product yield. Studies of chemical reaction dynamics of the thermal cracking of latex at 200-400°C showed that the process should be termed as hydrogen-tranfer (H-T) hydrocracking of latex under ambient pressure conditions. The hydrogen rich cracked trilcrpenoids act as the H-donors in this process, where nascent hydrogen atoms and free radicals chemically plug the cracked moities to stabilise these. Latex was also coagulated and the H-T hydrocracking of the feedstock coagulum gave a higher yield of cracked oil in comparision lo that from the dried latex. A model triterpene compound, ursolic acid has been subjected to H-T hydrocracking to understand the process of hydrocracking of latex under similar conditions and it was found that triterpencs on H-T hydrocracking produced only liquid and gaseous products and no solid char. The temperature for hydrocracking of latex has been optimized to 350°C and molecular sieve was round to catalyse the H-T Hytrocraking process to yield more liquid product The distillation range of cracked latex on(CLO)Obtained from H.T Hytrocracking of C procera Latex indicated that it can be used as fuel. Moreover CLO resembled diesel fuels and was predominantly paraffinic in nature as characterised by NMR and FTIR spectral analysis. A process has been recommended for gelling value added fuels and chemicals from C. procera latex.     

KINETICS OF CORN COB CHAR GASIFICATION IN CARBON DIOXIDE

ABSTRACT

The Reactivity of corn cob char in CO₂ has been studied on a thermogravimetric balance to develop a rate equation for the design of biomass gasifiers operating on corn cob char. Experiments in the range of 650-1000^°C were conducted with cylindrical shaped pellets of 1 cm diameter having L/D=l. The average porosity of the pellets was 0.5. It was observed that the rate of the CO₂/char reaction decreased with increase in temperature from 650-750^°C and then increased with temperature upto 1000^°C.

The data obtained at temperatures 750^°C and above has been used to determine a rate equation for char gasification. It has been found that the reaction proceeds according to the Sharp Interface Model (SIM) with a first order chemical reaction as the rate controlling step. The activation energy is found to be 40 Kcal/mole with frequency factor being 1.2 × 10⁷ mm/sec. Analysis of the data obtained for the decreasing reaction rate regime (650-750^°C) indicates that the change in the ash structure result in this kind of behavior.     

The Aromatization of Different FCC Naphtha Fractions over a P-Zn/HZSM-5 Catalyst

Abstract

The aromatization reaction performance of P-Zn/HZSM-5 catalyst was investigated on a fixed bed reactor using five fluid catalytic cracked (FCC) gasoline fractions (<100°C, 50°C–100°C, <120°C, 75°C–120°C, and full fraction) as feedstock, and the effect of feedstock on aromatization is discussed. The results showed that the activity and stability of P-Zn/HZSM-5 catalyst for the aromatization of the 50°C–100°C fraction were high in definite reaction conditions. After 16 hr, the content of olefin and aromatics in liquid product were 5.23 and 79.9%, respectively. The liquid product of low olefin and high aromatics was obtained. The distribution of benzene, toluene, and xylene in liquid product of 50°C–100°C fraction was investigated during aromatization, and the result showed that the toluene content was maximum among the three aromatics contents, the benzene content was minimum at the beginning of the reaction, xylene content became maximum, and benzene was still minimum after reacting for 20 hr. The content of C₉ ⁺ aromatics increased at the first stage of the reaction and then decreased with the increasing reaction time.     

Simulation of the Regeneration of a Coked Aromatization Catalyst

Abstract

Taking into account the effects of finite chemical reaction rate, internal diffusion and reaction heat release, a theoretical model was developed to investigate the regeneration process of a single coked aromatization catalyst of 1 mm in diameter. The results showed that at 650°C, the chemical reaction rate is the limiting step and the regeneration process is characterized by the homogeneous model. At temperatures above 750°C, regeneration process is affected strongly by the internal diffusion of oxygen. The maximum temperature rise of the catalyst particle increases with increasing initial regeneration temperature. The maximum temperature rise also increases with the increase of the initial carbon load and the CO₂/CO ratio in product gas; however, the regeneration time needed for a certain degree of burn-off also increases.