Fischer Assay Oil Yield Research Articles

Oil shale pyrolysis in a moving bed with internals enhanced by rapid preheating in a heated drop tube

The enhanced oil shale pyrolysis in a moving bed with internals (MBI) by rapid preheating in a drop tube was developed to improve the quality of shale oil through reaction regulation in stages. Initially rapid preheating of oil shale in the upper drop tube endowed the generation of massive free radical fragments and volatile precursors, which would simultaneously restrict the remarkable release of volatiles from particles to minimize the gas-phase secondary reactions. The preheated oil shale subsequently fell into the lower MBI to shape a granular bed with the cocurrent flow of heat and volatiles. In the MBI, the oil shale pyrolysis and volatiles reactions were directed and regulated by matching the flow and temperature fields to realize the selective cracking of heavy fraction in shale oil. The granular bed also served as a filter for the in-situ removal of dust entrained by the volatiles. The shale oil yield reached 83.0% of Fischer Assay oil yield, its light fraction was as high as 89.2 wt% and dust content was as low as 0.6 wt%. The advantages of pyrolysis in the MBI enhanced by rapid preheating were further justified by comparison with other pyrolysis processes.

Sequence Stratigraphy and Geochemistry of Oil Shale Deposits in the Upper Cretaceous Qingshankou Formation of the Songliao Basin, NE China: Implications for the Geological Optimization of In Situ Oil Shale Conversion Processing

The Songliao Basin contains some of the largest volumes of oil shales in China; however, these energy sources are located in areas covered by arable land, meaning that the best way of exploiting them is likely to be environmentally friendly in situ conversion processing (ICP). Whether the oil shales of the Songliao Basin in the Qingshankou Formation are suitable for ICP remain controversial. In this paper, through sequence stratigraphic correlations, three main thick oil shale layers (N1, N2, and N3) of the Sequence1 (Sq1) unit in the first member of Qingshankou Formation (K2qn1) are confirmed as consistently present throughout the Southeastern Uplift region of the basin. The spectral trend attributes reflect that the lake reached a maximum flood surface of the K2qn1 in N2 oil shale layer, and the total organic carbon (TOC) and Fischer assay (FA) oil yield are significantly increasing. The N2 and N3 oil shale layers were deposited in a high lake level environment associated with ingressions of ocean water. The oil shale in these layers with the characteristics of high TOC (maximum of 23.9 wt %; average of 7.2 wt %), abundance of aquatic organic matter (OM) (maximum hydrogen index (HI) of 1080.2 mg/g; average of 889.9 mg/g) and carbonate contents (maximum of 29.5%; average of 15.4%). The N2 and N3 oil shale layers have higher brittleness index (BI) values (generally 40–50%), larger cumulative thicknesses (maximum of 13.3 m; average of 12.0 m), and much higher source potential index (SPI) values (0.92 and 0.88 tHC/m2, respectively) than the N1 oil shale layer within Sq1 transgressive system tracts (TST), indicating that the N2 and N3 layers are prospective targets for ICP. In addition, oil shales buried to depths of <1000 m have strong hydrocarbon generation capacities that make them suitable for ICP.

Secondary cracking of volatile and its avoidance in infrared-heating pyrolysis reactor

This study aims to compare the pyrolysis behavior of Huadian oil shale in two infrared heating fixed bed reactors with different directions of infrared beam. Our previous work has shown that fast pyrolysis of oil shale conducted in the shallow fixed bed infrared heating reactor (co-current) presented the massive secondary reactions, which lowered the shale oil production (Siramard et al., 2017). Conversely, the cross-current infrared achieved shale oil yields higher than the Fischer Assay oil yield (13.07 wt% of dry basis), such as 117.7% of the Fischer Assay yield at our realized highest heating rate of 7 °C/s under a specified pyrolysis temperature of 550 °C. The shale oil from the cross-current infrared heating reactor was obviously heavier than the oil obtained from the co-current heating reactor. Thus, the infrared cross heating evidently suppressed the secondary reactions toward volatile. Our realized shale oil yield could reach 13.67 wt% or 122.5% of the Fischer Assay yield under reducing pyrolysis pressure of 0.6 atm, indicating that lower pressure is also beneficial to the release of volatile and reduction of the secondary cracking reactions. This work shows essentially that the infrared cross heating provides an effective merge of the advantages from quick heating and minimization of secondary cracking reactions to enable the shale oil yields being higher than the Fischer Assay oil yield.

Pyrolysis of Huadian Oil Shale in an Infrared Heating Reactor

Pyrolysis of Huadian oil shale was investigated in a newly designed shallow fixed bed reactor mounted with infrared heating to clarify the pyrolysis behavior at different heating rates and pyrolysis temperatures under minimized secondary reactions to volatiles in an oil shale bed. The maximum shale oil recovery was obtained under the proper conditions of a heating rate of 0.5 °C/s, a pyrolysis temperature of about 550 °C, a reduced reaction pressure (0.6 atm in this work), and for a single-layer oil shale bed. The highest shale oil yield under such conditions was close to 100% of the Fischer Assay oil yield (11.10 wt % of dry basis). For the adopted infrared-heating reactor, increasing the heating rate decreased the shale oil yield but increased the gas production. The total hydrogen in volatile products including shale oil and pyrolysis gas increased with raising the heating rate, and the total volatile production was higher for the infrared quick heating pyrolysis (heating rate: 25 °C/s) than that for t...

Characteristics of oil shale pyrolysis in a two-stage fluidized bed

Abstract Rapid pyrolysis of oil shale coupled with in-situ upgrading of pyrolysis volatiles over oil shale char was studied in a laboratory two-stage fluidized bed (TSFB) to clarify the shale oil yield and quality and their variations with operating conditions. Rapid pyrolysis of oil shale in fluidized bed (FB) obtained shale oil yield higher than the Fischer Assay oil yield at temperatures of 500–600 °C. The highest yield was 12.7 wt% at 500 °C and was about 1.3 times of the Fischer Assay oil yield. The heavy fraction (boiling point > 350 °C) in shale oil at all temperatures from rapid pyrolysis was above 50%. Adding an upper FB of secondary cracking over oil shale char caused the loss of shale oil but improved its quality. Heavy fraction yield decreased significantly and almost disappeared at temperatures above 550 °C, while the corresponding light fraction (boiling point

Pyrolysis characteristics of Longkou oil shale under optimized condition

Factors influencing the pyrolysis process of Longkou oil shale, such as nitrogen flow rate, pyrolysis temperature, particle size, and heating rate, were investigated in order to optimize the pyrolysis condition and reduce the secondary reactions. Oil yield reached the maximum value, 17.46 %, higher than Fischer assay oil yield, at heating rate 15 °C min−1 up to 550 °C under 0.6 L min−1 nitrogen flow rate for 2- to 3-mm oil shale particles. Compared with the retorting gas obtained from Fischer assay, the retorting gas under optimized condition had a higher organic/inorganic gas ratio and alkanes/alkenes (C1–C5), due to the inhibition of the gas cracking or secondary gas phase reactions. And the shale oil obtained from optimized condition had a lower IBP and higher distilled mass percent when reaching the same end temperature, 750 °C. The content of total alkanes and alkenes in the shale oil under optimized condition was 401 and 181 mg g oil −1 , which were higher than those from Fischer assay, but the C8–C10 alkenes were lower, proving that optimizing pyrolysis condition was beneficial to reducing the secondary reactions.

Oil shale pyrolysis in indirectly heated fixed bed with metallic plates of heating enhancement

This study is devoted to improving the heating to oil shale particles and in turn the yield and quality of shale oil in fixed bed reactors indirectly heated through use of internals. Metallic heating plates were vertically welded on the reactor wall as heating enhancement internals to provide extra heating surfaces inside the oil shale bed and to increase the high-temperature heating surface area by 35% to 210%. Comparison of heating rate to particles and shale oil yield was made between the reactors without and with the plate internals. Utilizing internals evidently enhanced the heating to oil shale particles and shortened pyrolysis time by 30% to 50%. The shale oil yield increased by 7% to reach 90% of the Fischer Assay oil yield (8.98wt.%, dry base) when the heating surface area was increased by 70–110%. With increased heating surface area above 110%, the shale oil yield manifested conversely a slight decrease. Nonetheless, the fraction of light oil (boiling point <350°C by analysis in simulation GC) was increased to about 66wt.% from 60.94wt.% for the reactor without any heating plate. Characterizing the char samples at different lateral positions of the oil shale bed justified that the flow of gaseous pyrolysis product in the reactor was guided to the vicinity of heat transfer plates to speed up gas exhaust and selective cracking. Consequently, adding heat transfer plates into an indirectly heated reactor would obviously intensify the heating to the oil shale bed and also elevate the pyrolysis oil yield and quality.

Catalytic hydroretorting of eastern US oil shales: CHESS process

Laboratory tests of the CHESS process were conducted using beneficiated Alabama oil shale and regenerable catalysts at 500°C and 7 MPa with 20 min shale residence time. Product oil sulfur and nitrogen contents were reduced by up to 98 and 74% respectively, compared with uncatalysed pressurized fluidized-bed hydroretorting (PFH). Operation with the catalysts reduced the density of the oil by 10% to 0.909 g cm −3 while still achieving 200% Fischer assay oil yield.

Oil yields from combustion retorting of mixtures of Australian low rank oil shale and lignites

Rundle oil shale containing 12.9 wt.% of organic carbon was retorted using a combustion-type retort. It was possible to quantify the reduction in oil yield (compared with Fischer assay) due to the combustion of oil vapour during retorting. The oil yield was only 7.2 wt.%, compared with a Fischer assay oil yield of 8.7 wt.%, when retorting was carried out with excess air but no additional source of carbon. Oil yields could be improved by mixing lignite, available from within the Rundle deposit, with oil shale before retorting. Oil yields, based on charge, from mixtures containing more than 10% lignite decreased with increasing lignite content, but were virtually identical with Fischer assay oil yields from the mixtures. The maximum oil yield was about 8.5 wt.% for 6 wt.% lignite in the mixtures. The resulting oils were slightly heavier and more aromatic than the oils obtained by Fischer assay, but showed no significant difference in oxygen content.

Pressurized fluidized-bed hydroretorting of six eastern shales in batch and continuous laboratory-scale reactors

The Institute of Gas Technology has conducted pressurized fluidized-bed hydroretorting (PFH) tests of six Eastern US oil shales in batch and continuous laboratory-scale reactors. Batch tests were conducted to determine the effects of temperature (from 480 to 590 °C) and pressure (from 2.8 to 7.0 MPa) on oil yield and carbon conversions for shales from Alabama, Indiana, Kentucky, Michigan, Ohio and Tennessee. Continuous laboratory-scale unit tests were conducted with Indiana shale at similar temperatures and at pressures of 2.8 and 4.2 MPa. Carbon conversion to oil was found to increase significantly with increasing hydrogen pressure for all six shales while the relationship between temperature and oil yield was different for each shale. Carbon conversion to gas increased with increasing temperature but was generally unaffected by changes in pressure. The highest oil yield for each shale was obtained at the highest pressure tested of 7.0 MPa. PFH processing has been shown to produce in excess of 200% of the Fischer Assay oil yield for all six shales and up to 268% for one of the shales.

Organic petrography of Mississippian and Devonian shales in east-central Kentucky

The Devonian and Mississippian oil shales of east-central Kentucky are classified as marinites. The petrographic composition of the kerogen in the shales is complex, and significant amounts of macerals from all of the major groups are present. Unfigured alginite (lamalginite) and bituminite are the most abundant macerals present, followed by vitrinite and inertinite (fusinite and semifusinite). Figured alginite (telalginite) includes Leosphoridia and Tasmanites; a minor amount of sporinite (~1% or less) is also present. The maceral composition of the Cleveland and Sunbury Shale interval from a core taken in Fleming County, Kentucky was determined quantitatively. The liptinite suite in the Sunbury interval was dominated by bituminite, while the Cleveland contained higher proportions of alginite. The total amount of inertinite plus vitrinite was found to be relatively constant. Variations in maceral composition affect the scatter of Fischer assay oil yield versus organic carbon relations for Eastern US oil shale. The kerogen macerals were found to correlate selectively with certain trace elements (e.g. Cr, Cu, V and Zn), suggesting that the maceral composition may be related to shale provenance. Bituminite:alginite ratio was found to correlate selectively with trace element concentration and supports the concept that the organic precursors for this maceral were bacterial decay products.

Partial combustion retorting of several kinds of oil shales.

A retorting study was conducted on eleven kinds of oil shales using a partial combustion retorting method (PCM). Every oil shale studied could be retorted with air alone without introducing any external energy. The oil shales whose Fischer assay oil yields were not less than 9% had total oil yields in the range from 81 to 105% based on the Fischer assay oil yields, while those oils having yields less than 9% were significantly lower than the others. In the case of Condor oil shale, part of the oil vapor was thought to be burned during the partial combustion retorting to compensate for the shortage of thermal energy supplied by the combustion of the carbon residue on the spent shale due to its low organic carbon content. Combustion of the spent shale seemed to require an amount of air proportional to the percentage of the aromatic carbon in the raw oil shale. Shale oils obtained by PCM had slightly higher densities and H/C ratios, and lower quantities of lighter fractions than those obtaind by Fischer assay.

Pyrolysis of Rundle oil shale in a continuous fluidized bed retort

Experimental results for the pyrolysis of Rundle oil shale in a 5 kg h − 1 fluidized bed pilot plant are reported. Experiments have been conducted over a range of temperatures, 480–540 °C, particle residence time in the range 18–35 min and with two particle size fractions, 0.15–0.53 mm and 0.53–0.99 mm. Increasing the retorting temperature resulted in a large increase in the hydrocarbon gas yield due to thermal cracking reactions. Oil yields less than Fischer assay were observed, probably due to coking of oil on the burnt shale. Over the ranges covered, particle size and solids residence time did not affect oil yield, relative to Fischer Assay oil yield. G.c.-m.s. has been used to study the effect of process parameters on oil composition. The volatility and aromaticity of the fluid bed oil were higher than for Fischer assay oil, and oil volatility and aromaticity increased with retorting temperature as a result of an increase in thermal cracking reactions with temperature.

Correlation between the amount of carbon in shale oils and carbon distribution of oil shales: estimation of carbon recovery by a multiple regression method

Solid s ta te C P / M A S 13C N M R spec t roscopy is a very a t t rac t ive m e t h o d for the di rect d e t e r m i n a t i o n of the a roma t i c i ty of solid fuels. T h e r e are m a n y papers repor t ing the appl ica t ion of th is t echn ique to oil shale cha rac te r i za t ion [1,2]. Maciel et al. [I] proposed that aromatic carbon in oil shale kerogen is responsible for the carbonaceous residue in spent shale after retorting [ 3 ]. They also proposed a linear correlation between the percentage of aliphatic carbon in an oil shale and Fischer assay oil yield [4]. This correlation is useful for estimating Fischer assay oil yield from the results of other oil shales having similar characteristics. Problems with this correlation can arise due to depending on sedimentary factors such as geologic age and geographic location. Furthermore, the aromaticity of shale oil obtained by Fischer assay is considered to depend on that of kerogen [ 5 ]. A part of the aromatic carbon seems to contribute to the aromaticity of shale oil. This suggests that the aromaticity of kerogen has to be considered to estimate Fischer assay oil yield. We have recently determined the contents of aliphatic, aromatic and inorganic carbon in oil shales by solid state CP/MAS '3C NMR technique and elementary analysis. Then, from these results, we have estimated the percentage of carbon which formed shale oils by Fischer assay, using a multiple regression method. In this paper, we will define the carbon which is converted to that in shale oil by Fischer assay as 'converted carbon'. Although our experiment is designed to estimate Fischer assay 'carbon' yield rather than Fischer assay oil yield, it is considered valuable in estimating the oil yield because shale oil usually contains about 80 wt.% of organic carbon.

High pressure high temperature electron spin resonance study of oil shale retorting

Previous studies of high pressure retorting under hydrogen have reported large increases in the Fischer assay oil yield for carbonaceous shales. A high temperature, high pressure, electron spin resonance cavity has been constructed and used to measure spin concentrations of the radicals during pyrolysis. The results are independent of the gas and do not show the expected reduction in spin concentration for hydrogen due to hydrogen capping; this can be explained by the failure of steady state electron spin resonance measurements to detect rapid radical formation and decay processes.

Trace element distribution and oil yield data from the parachute creek member of the green river formation, colorado

The determination of trace element concentrations in oil shale before mining and retorting is required for proper solid-waste management planning. Using routine Fischer assay oil yield data collected during resource characterization as indicators of potential trace element concentrations could lead to a standard method of identifying strata containing high trace element levels. In order to determine a correlation between trace element concentrations and oil yield, shale samples were selected from four statigraphic zones of the Parachute Creek Member of the Green River Formation for analysis. All samples were analyzed for total elemental concentrations, mineralogy, and Fischer assay oil yield. The results of these analyses demonstrated that the Mahogany zone shales contain significantly greater trace element concentrations (antimony, arsenic, cadmium, chromium, copper, lead, lithium, mercury, molybdenum, nickel, selenium, silver, and vanadium) than the other three shale zones. These high trace element concentrations have been identified within well-defined interbedded tuff deposits in the Mahogany zone. In addition, all trace elements evaluated, except boron, show either increasing or decreasing concentrations as oil yield increases within all oil shale zones. With an increased number of analyses of existing oil shale cores, oil yield data will be correlated to specific stratigraphic units containing high trace element concentrations.

The effects of pyrolysis conditions on Israeli oil shale properties

This paper reports on a study which was undetaken to identify the influence of pyrolysis parameters on the qaulity and quantity of oil from the EF'E oil shale deposit in Israel. Pyrolysis experiments were performed in three reactors which allowed variations in heating rate, bed geometry, pressure, temperature, and residence time of the pyrolysis products. These parameters were varied in a series of pyrolysis tests to identify the controlling mechanisms. The pyrolysis results indicate that high oil yields can be achieved with proper process conditions. Secondary reactions of the oil (cracking and coking) are both minimized when temperature and residence time for oil in the reaction zone are kept to a minimum. When the oil remains in the hot zone, such as in the Fischer Assay, cracking lowers the oil yield and increases light hydrocarbon gases. In addition secondary reactions increase the aromaticity, decrease the nitrogen and increase the sulphur content of the oil. All evidence suggests that the Israeli shale oil is more prone to cracking than a Colorado Green River shale oil on which similar tests were performed. The average molecular weight of the Israeli oil is lower, the rate of evolution is higher and the Fischer Assay oil yield is lower.

Comments on the Modified Fischer Assay of Eastern oil shales of Kentucky

The Modified Fischer Assay is the accepted method for evaluating the potential liquid fuel yield of an oil shale. For a given shale, percent of Fischer Assay oil yield has become the standard used for judging technologies. The method has been developed for and is well understood when applied to oil shales in the western United States. However, the assay can be successfully applied to eastern United States oil shales only if care is taken in several areas that prove less important for its successful application to western shales. In particular, standardized sample preparation and handling with minimum air exposure of pulverized shale is required; a well-controlled and reproducible heating profile during retorting must be employed; and consistently effective liquid product collection must be accomplished. These considerations have a major influence on assay accuracy. Only with care in these areas, can Modified Fischer Assays suitable for eastern shale resource evaluations and technology comparisons be obtained.

AIR OXIDATION OF EASTERN OIL SHALES OF KENTUCKY. II. THE EFFECTS OF AMBIENT AUTOXIDATION

ABSTRACT Ambient air oxidation leads to lower Fischer assay oil yields and often lower process yields from retorting of eastern oil shales. Slight changes in the kerogen and mineral matter of the oil shale and in its pyrolysis products, both liquid and gaseous, were evident following autoxidation. Experimental observations suggest that the hydrogen deficiency of eastern kerogen, as compared to western kerogen, makes its synfuel potential (by Fischer assay) a more sensitive function of the degree of oxidation. A better yield of oil from oxidized eastern oil shale could be obtained by dissolving away sulfates and other water soluble oxidized materials prior to retorting. The air oxidation of pyrite was demonstrated by SEH, and addition of iron(II) sulfate was shown to reduce assay oil yields. Such observations suggest that combusted shale may not always be a suitable heat transfer agent for atmospheric pressure retorting applications.

13C NMR measurements of the genetic potentials of oil shales

Cross polarization, magic-angle spinning 13C NMR measurements have been made on raw oil shales that represent a variety of geologic ages, origins, depositional environments and source locations. A high degree of correlation was established between the fraction of aliphatic carbon measured by 13C NMR, and the genetic potential, calculated from Fischer assay data. The correlation is independent of the type of kerogen in the raw shale, and its degree of evolution. A short discussion on the validity of various correlations between physical/chemical properties of oil shales and Fischer assay oil yields is given.