Delayed coking and dedusting process

A delayed coking and dedusting process in which dust laden heavy oil derived from solid hydrocarbon-containing material, such as oil shale, coal or tar sand, is preheated in a furnace and thermal cracked in a retort to yield light oils and middle oils. Preferably, steam is injected into the dust laden heavy oil before the dusty oil is heated in the furnace to minimize coking in furnace tubes and furnace outlet lines. The thermal cracked dusty oil leaves a residual dust enriched, coked material that can be combusted to provide a portion of the solid heat carrier material for use in retorting oil shale, coal or tar sand.

BACKGROUND OF THE INVENTION 
This invention relates to a process for retorting solid, 
hydrocarbon-containing material such as oil shale, coal and tar sand and 
dedusting and upgrading the effluent product stream. 
Researchers have now renewed their efforts to find alternate sources of 
energy and hydrocarbons in view of recent rapid increases in the price of 
crude oil and natural gas. Much research has been focused on recovering 
hydrocarbons from solid hydrocarbon-containing material such as oil shale, 
coal and tar sand by pyrolysis or upon gasification to convert the solid 
hydrocarbon-containing material into more readily usable gaseous and 
liquid hydrocarbons. 
Vast natural deposits of oil shale found in the United States and elsewhere 
contain appreciable quantities of organic matter known as "kerogen" which 
decomposes upon pyrolysis or distillation to yield oil, gases and residual 
carbon. It has been estimated that an equivalent of 7 trillion barrels of 
oil are contained in oil shale deposits in the United States with almost 
sixty percent located in the rich Green River oil shale deposits of 
Colorado, Utah, and Wyoming. The remainder is contained in the leaner 
Devonian-Mississippian black shale deposits which underlie most of the 
eastern part of the United States. 
As a result of dwindling supplies of petroleum and natural gas, extensive 
efforts have been directed to develop retorting processes which will 
economically produce shale oil on a commercial basis from these vast 
resources. 
Generally, oil shale is a fine-grained sedimentary rock stratified in 
horizontal layers with a variable richness of kerogen content. Kerogen has 
limited solubility in ordinary solvents and therefore cannot by recovered 
by extraction. Upon heating oil shale to a sufficient temperature, the 
kerogen is thermally decomposed to liberate vapors, mist, and liquid 
droplets of shale oil and light hydrocarbon gases such as methane, ethane, 
ethene, propane and propene, as well as other products such as hydrogen, 
nitrogen, carbon dioxide, carbon monoxide, ammonia, steam and hydrogen 
sulfide. A carbon residue typically remains on the retorted shale. 
Shale oil is not a naturally occurring product, but is formed by the 
pyrolysis of kerogen in the oil shale. Crude shale oil, sometimes referred 
to as "retort oil," is the liquid oil product recovered from the liberated 
effluent of an oil shale retort. Synthetic crude oil (syncrude) is the 
upgraded oil product resulting from the hydrogenation of crude shale oil. 
The process of pyrolyzing the kerogen in oil shale, known as retorting, to 
form liberated hydrocarbons, can be done in surface retorts in aboveground 
vessels or in situ retorts underground. In principle, the retorting of 
shale and other hydrocarbon-containing materials such as coal and tar 
sand, comprise heating the solid hydrocarbon-containing material to an 
elevated temperature and recovering the vapors and liberated effluent. 
However, as medium grade oil shale yields approximately 25 gallons of oil 
per ton of shale, the expense of materials handling is critical to the 
economic feasibility of a commercial operation. 
In order to obtain high thermal efficiency in retorting, carbonate 
decomposition should be minimized. Colorado Mahogany zone oil shale 
contains several carbonate minerals which decompose at or near the usual 
temperature attained when retorting oil shale. Typically, a 28 gallon per 
ton oil shale will contain about 23% dolomite (a calcium/magnesium 
carbonate) and about 16% calcite (calcium carbonate), or about 780 pounds 
of mixed carbonate minerals per ton. Dolomite requires about 500 BTU per 
pound and calcite about 700 BTU per pound for decomposition, a requirement 
that would consume about 8% of the combustible matter of the shale if 
these minerals were allowed to decompose during retorting. Saline sodium 
carbonate minerals also occur in the Green River formation in certain 
areas and at certain stratigraphic zones. The choice of a particular 
retorting method must therefore take into consideration carbonate 
decomposition as well as raw and spent materials handling expense, product 
yield and process requirements. 
In surface retorting, oil shale is mined from the ground, brought to the 
surface, crushed and placed in vessels where it is contacted with a hot 
heat transfer carrier, such as ceramic or metal balls, hot spent shale or 
sand for heat transfer. The resulting high temperatures cause shale oil to 
be liberated from the oil shale leaving a retorted, inorganic material and 
carbonaceous material such as coke. The carbonaceous material can be 
burned by contact with oxygen at oxidation temperatures to recover heat 
and to form a spent oil shale relatively free of carbon. Spent oil shale 
which has been depleted in carbonaceous material is removed from the 
reactor and recycled as heat carrier material or discarded. The combustion 
gases are dedusted in a cyclone or electrostatic precipitator. 
Some well-known processes of surface retorting are: N-T-U (Dundas Howes 
retort), Kiviter (Russian), Petrosix (Brazilian), Lurgi-Ruhrgas (German), 
Tosco II, Galoter (Russian), Paraho, Koppers-Totzek, Fushum (Manchuria), 
gas combustion and fluid bed. Process heat requirements for surface 
retorting processes may be supplied either directly or indirectly. 
The Tosco II process and modifications thereof are described in U.S. Pat. 
Nos. 3,008,894, 3,034,979 and 3,058,903 and at pages 85-88 of the 
Synthetic Fuels Data Handbook by Cameron Engineers, Inc. (Second Edition 
1978). 
The Lurgi-Ruhrgas process and modifications thereof are described in U.S. 
Pat. Nos. 3,655,518; 3,703,442; 3,962,043; 4,038,045 and 4,054,492 and in 
the articles by Marnell, P., entitled Lurgi/Ruhrgas Shale Oil Process, 
published in Hydrocarbon Processing, pages 269-271 (September 1976); 
Schmalfeld, I. P., The Use of the Lurgi-Ruhrgas Process for the 
Distillation of Oil Shale, Volume 70, Number 3, Quarterly of the Colorado 
School of Mines, pages 129-145 (July 1975); Rammler, R. W.; The Retorting 
of Coal, Oil Shale, and Tar Sand by Means of Circulated Fine-Grained Heat 
Carriers as a Preliminary Stage in the Production of Synthetic Crude Oil, 
Volume 65, Number 4, Quarterly of the Colorado School of Mines, pages 
141-167 (October 1970) and at pages 81-85 of the Synthetic Fuels Data 
Handbook by Cameron Engineers, Inc. (Second Edition 1978). 
When retorting, thermocracking and coking are carried out simultaneously, 
carbonaceous residue, also referred to as "coke," "residual carbon" or 
"carbon residue," is deposited on retorted and heat carrier material and 
carried along with the effluent product stream. As the effluent product 
stream and retorted and heat carrier material circulate through various 
parts of the system at elevated temperatures, coke is deposited along the 
internal walls of pipes, vessels, cyclones and other equipment. The 
deposition and buildup of coke in the system restricts the flow rate and 
throughput capacity of the product stream, as well as the retort and heat 
carrier material. Coke accumulation also results in the formation of 
protrusions and depressions on the internal walls of pipes, vessels, 
cyclones and other equipment which interfere with the smooth linear flow 
of the effluent product stream as well as the retorted and heat carrier 
material. Coke deposits can further cause overheating and clog vital parts 
of equipment resulting in costly shutdown (downtime) and tedious removal 
of the accumulated carbonaceous residue. Moreover, the accumulation of 
coke in cyclones impedes dedusting of the effluent product stream. Delayed 
coking of crude oil and injection of steam to increase the velocity of 
crude oil and minimize coking are described at pages 131-136 and 145 of 
the book Petroleum Processing by R. J. Hengstebeck, published by 
McGraw-Hill Book Company, Inc. (1959). 
During fluid bed, moving bed and other types of surface retorting, 
decrepitation of oil shale occurs creating a popcorning effect in which 
particles of oil shale collide with each other and impinge against the 
walls of the retort forming substantial quantities of minute entrained 
particulates of shale dust. The use of hot spent shale or sand as heat 
carrier material aggravates the dust problem. Rapid retorting is desirable 
to minimize thermal cracking of valuable condensable hydrocarbons, but 
increases the rate of decrepitation and amount of dust. Shale dust is also 
emitted and carried away with the effluent product stream during modified 
in situ retorting as a flame front passes through a fixed bed of rubblized 
shale, as well as in fixed bed surface retorting, but dust emission is not 
as aggravated as in other types of surface retorting. 
Shale dust ranges in size from less than 1 micron to 1000 microns and is 
entrained and carried away with the effluent product stream. Because shale 
dust is so small, it cannot be effectively removed to commercially 
acceptable levels by conventional dedusting equipment. 
The retorting, carbonization or gasification of coal, peat and lignite and 
the retorting or extraction of tar sand and gilsonite create similar dust 
problems. 
After retorting, the effluent product stream of liberated hydrocarbons and 
entrained dust is withdrawn from the retort through overhead lines and 
subsequently conveyed to a separator, such as a single or multiple stage 
distillation column, quench tower, scrubbing cooler or condenser, where it 
is separated into fractions of light gases, light oils, middle oils and 
heavy oils with the bottom heavy oil fraction containing essentially all 
of the dust. As much as 40% by weight of the bottom heavy oil fraction 
consists of dust. 
It is very desirable to upgrade the bottom heavy oil into more marketable 
products, such as light oils and middle oils, but because the heavy oil 
fraction is laden with dust, it is very viscous and cannot be pipelined. 
Dust laden heavy oil plugs up hydrotreaters and catalytic crackers, gums 
up valves, heat exchangers, outlet orifices, pumps and distillation 
towers, builds up insulative layers on heat exchange surfaces reducing 
their efficiency and fouls up other equipment. Furthermore, the dusty 
heavy oil corrodes turbine blades and creates emission problems. If used 
as a lubricant, dusty heavy oil is about as useful as sand. Moreover, the 
high nitrogen content in the dusty heavy oil cannot be refined with 
conventional equipment. 
In an effort to solve this dust problem, electrostatic precipitators have 
been used as well as cyclones located both inside and outside the retort. 
Electrostatic precipitators and cyclones, however, must be operated at 
very high temperatures and the product stream must be maintained at or 
above the highest temperature attained during the retorting process to 
prevent any condensation and accumulation of dust on processing equipment. 
Maintaining the effluent steam at high temperatures is not only expensive 
from an energy standpoint, but it allows detrimental side reactions, such 
as cracking, coking and polymerization of the effluent product stream, 
which tends to decrease the yield and quality of condensable hydrocarbons. 
Over the years various processes and equipment have been suggested to 
decrease the dust concentration in the heavy oil fraction and/or upgrade 
the heavy oil into more marketable light oils and medium oils. Such prior 
art dedusting processes and equipment have included the use of cyclones, 
electrostatic precipitators, pebble beds, scrubbers, filters, electric 
treaters, spiral tubes, ebullated bed catalytic hydrotreaters, desalters, 
autoclave settling zones, sedimentation, gravity settling, percolation, 
hydrocloning, magnetic separation, electrical precipitation, stripping and 
binding, as well as the use of diluents, solvents and chemical additives 
before centrifuging. Typifying those prior art processes and equipment and 
related processes and equipment are those found in U.S. Pat. Nos. 
2,235,639; 2,717,865; 2,719,114; 2,723,951; 2,793,104; 2,879,224; 
2,899,376; 2,904,499; 2,911,349; 2,952,620; 2,982,701; 2,968,603; 
3,008,894; 3,034,979; 3,058,903; 3,252,886; 3,255,104; 3,468,789; 
3,560,369; 3,684,699; 3,703,442; 3,784,462; 3,799,855; 3,808,120; 
3,900,389; 3,901,791; 3,929,625; 3,974,073; 3,990,885; 4,028,222; 
4,040,958; 4,049,540; 4,057,490; 4,069,133; 4,080,285; 4,088,567; 
4,105,536; 4,151,073; 4,159,949; 4,162,965; 4,166,441; 4,182,672; 
4,199,432; 4,220,522 and 4,246,093 as well as in the articles of Rammler, 
R. W., The Retorting of Coal, Oil Shale and Tar Sand By Means of 
Circulated Fine-Grained Heat Carriers as a Preliminary Stage in the 
Production of Synthetic Crude Oil, Volume 65, Number 4, Quarterly of the 
Colorado School of Mines, pages 141-167 (October 1970) and Schmalfeld, I. 
P., The Use of The Lurgi/Ruhrgas Process For The Distillation of Oil 
Shale, Volume 70, Number 3, Quarterly of the Colorado School of Mines, 
pages 129-145 (July 1975). These prior art processes and equipment have 
not been successful in decreasing the dust concentration in the heavy oil 
fraction to commercially acceptable levels. 
It is therefore desirable to provide an improved process, which overcomes 
most, if not all, of the preceding problems. 
SUMMARY OF THE INVENTION 
A delayed coking and dedusting process is provided for dedusting and 
upgrading dust laden heavy oil derived from solid hydrocarbon-containing 
material, such as oil shale, coal and tar sand. The dedusted and upgraded 
oil can be safely pipelined through valves, outlet orifices, heat 
exchangers, pumps, distillation towers and refined in hydrotreaters and 
catalytic crackers. The novel process reduces dust emissions, decreases 
dust and coke buildup and diminishes corrosion of equipment. 
In the novel process, raw oil shale, coal or tar sand, is fed into a 
retort, such as a pyrolysis drum, screw conveyor or fluid bed, where it is 
contacted with hot solid heat carrier material, such as ceramic balls, 
metal balls, spent shale or sand to liberate an effluent product stream of 
hydrocarbons and entrained particulates of dust. The effluent product 
stream is withdrawn from the retort through overhead lines and conveyed to 
a separator, such as a single or multiple stage quench tower, scrubber, 
condenser or distillation column, sometimes referred to as a 
"fractionating column" or "fractionator." Steam can be injected into the 
retort to minimize the buildup of coke in the overhead lines. 
The separator separates the effluent product stream into fractions. 
Preferably, the temperature of the separator is controlled so that 
essentially all the dust is entrained in the solids bottom fraction of 
heavy oil. 
In order to dedust and upgrade the dust laden heavy oil fraction, the dust 
laden heavy oil fraction is fed to a furnace where it is heated. 
Preferably, the dust laden heavy oil fraction is heated to a temperature 
slightly less than the retorting temperature to improve thermal efficiency 
and decrease quantity, rate and temperature requirements of solid heat 
carrier material. Heating the dust laden fraction before it is fed into 
the retort also minimizes thermal shock, cracking and fracture of ceramic 
and metal balls, if ceramic or metal balls are used as the solid heat 
carrier material. Desirably, steam is injected into the dust laden heavy 
oil fraction before the dusty heavy oil fraction is fed into the furnace 
to increase the fraction's velocity through the furnace so as to minimize 
buildup of carbon residue in the furnace tubes and furnace outlet line. 
The preheated dust laden heavy oil fraction is then fed into the retort 
where it is contacted with the hot solid heat carrier material to thermal 
crack the heavy oil fraction into light and medium oils, leaving a coked 
residual material having a higher dust concentration. 
As used throughout this application, the term "retorted" 
hydrocarbon-containing material or "retorted" shale refers to 
hydrocarbon-containing material or oil shale, respectively, which has been 
retorted to liberate hydrocarbons leaving an organic material containing 
carbon residue. 
The term "spent" hydrocarbon-containing material or "spent" shale as used 
herein means retorted hydrocarbon-containing material or shale, 
respectively, from which essentially all of the carbon residue has been 
removed by combustion. 
The term "dust" as used in this application means particulates derived from 
solid hydrocarbon-containing material and ranging in size from less than 
one micron to 1000 microns. The particulates can include retorted and raw, 
unretorted hydrocarbon-containing material, as well as spent 
hydrocarbon-containing material or sand if the latter is used as solid 
heat carrier material during retorting. 
Dust derived from the retorting of oil shale consists primarily of calcium, 
magnesium oxides, carbonates, silicates and silicas. Dust derived from the 
retorting or extraction of tar sand consists primarily of silicates, 
silicas and carbonates. Dust derived from the retorting, carbonization or 
gasification of coal consists primarily of char and ash. 
The terms "normally liquid," "normally gaseous," "condensable," 
"condensed," or "noncondensable," are relative to the condition of the 
subject material at a temperature of 77.degree. F. (25.degree. C.) at 
atmospheric pressure. 
A more detailed explanation of the invention is provided in the following 
description and appended claims taken in conjunction with the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, a delayed coking and dedusting process and system 
10 is provided to retort hydrocarbon-containing material, such as oil 
shale, coal, tar sand, uintaite (gilsonite), lignite, and peat, for use in 
making synthetic fuels, and to dedust and upgrade the effluent product 
stream. While the process of the present invention is described 
hereinafter with particular reference to the processing of oil shale, it 
will be apparent that the process can also be used to retort other 
hydrocarbon-containing materials such as coal, tar sand, uintaite 
(gilsonite), lignite, peat, etc. 
In process and system 10, ceramic or metal spherical pebbles or balls, 
which provide solid heat carrier material, are heated in a ball heater 12 
to a temperature from 1000.degree. F. to 1400.degree. F. and preferably 
between 1200.degree. F. to 1300.degree. F. The balls can be of uniform 
size or varying sizes and range in diameter from 3/8 inch to 1 inch. The 
balls are conveyed through ball line 14 into a rotating pyrolysis drum 16 
of a retort 18 to directly contact, heat and retort raw or fresh oil 
shale. 
The raw oil shale which preferably contains an oil yield of at least 15 
gallons of shale oil per ton of shale particles, is crushed and sized to a 
maximum particle size of 1/2-inch and preheated to a temperature from 
550.degree. F. to 600.degree. F. before being fed into pyrolysis drum 16 
by feed line 20. The fresh oil shale can be crushed by conventional 
crushing equipment such as an impact crusher, jaw crusher, gyratory 
crusher or roll crusher and screened with conventional screening equipment 
such as a shaker screen or a vibrating screen. Feeding oil shale into 
pyrolysis drum 16 below 550.degree. F. should be avoided to prevent 
cracking, fracturing and rupturing of the balls. 
Oil shale in pyrolysis drum 16 is heated at atmospheric pressure from 
850.degree. F. to 1000.degree. F. and preferably about 890.degree. F. and 
conveyed by gravity flow to the upright accumulator 21 of retort 18. The 
balls crush the oil shale to a smaller size. Retorting of the oil shale 
commences in pyrolysis drum 16 and is completed in accumulator 21. 
The balls are discharged from accumulator 21 through ball discharge line 22 
where they are fed by gravity flow to a ball elevator or lift elevator 24. 
Elevator 24 conveys the balls through ball return line 26 to a ball heater 
12 where the balls are reheated and recycled back to pyrolysis drum 16. 
Retorted oil shale containing inorganic material and carbon residue are 
discharged from the bottom of accumulator 21 through solids discharge 
outlet 28. A rotating trommel screen in accumulator 34 directs the balls 
to ball discharge line 22 and the retorted material to solids discharge 
outlet 28. 
During retorting, an effluent product stream of hydrocarbons are liberated 
as a gas, vapor, mist, or liquid droplets and most likely a mixture 
thereof along with entrained particulates of shale dust. The effluent 
product stream mixed with entrained particulates of shale dust is 
discharged from the top of accumulator 21 through an overhead line 30 
where it is conveyed to a separator 32, such as a quench tower or 
fractionating column. Steam is injected into accumulator 21 through steam 
injection line 34 to prevent coking and buildup of carbon residue in 
overhead line 30. Preferably, superheated steam is injected at a 
temperature of 500.degree. F. above atmospheric pressure. The steam 
increases the flow rate and velocity of liberated hydrocarbons passing 
through overhead line 30. 
In separator 32, the effluent product stream is separated into fractions of 
light gases, light oils, middle oils and heavy oils in a manner well known 
in the art. From 15% to 35% by weight of the effluent product stream is 
separated as a solids bottom fraction. The solids bottom fraction, which 
is sometimes referred to as "dust laden heavy oil" or "dusty heavy oil," 
is a slurry and consists essentially of normally liquid heavy oil having a 
boiling point above 600.degree. F. and from 1% to 40% by weight and 
preferably at least 25% by weight entrained particulates of shale dust. 
The temperature in fractionator 32 can be varied from 500.degree. F. to 
800.degree. F. and preferably to a maximum temperature of 600.degree. F. 
at atmospheric pressure to assure that essentially all the dust gravitates 
to the bottoms fraction. 
The dust laden heavy oil is removed from the bottom of separator 32 and 
pumped downward through fractionating discharge line 34 into a furnace 38 
via furnace inlet line 40 by pump 36. Pump 36 maintains the inventory in 
separator 32. The flow rate of dust laden heavy oil from separator 32 
should be high enough to prevent the dust laden heavy oil from flooding 
separator 32 and low enough to prevent cavitation of the separator and 
damage to the pump. 
The heated dust laden heavy oil is discharged through furnace outlet line 
42 to a pressure control valve 44. Valve 44 steps down the pressure of the 
dusty heavy oil to slightly above atmospheric pressure. The reduced 
pressure oil flows from valve 44 into retort inlet line 46 where it is fed 
into raw oil shale line 30, so as to be mixed with the raw oil shale, 
before being recirculated to pyrolysis drum 16. Alternatively, the dust 
laden heavy oil can be fed directly into pyrolysis drum 16 without first 
being mixed with the raw oil shale. 
Steam is injected through steam injector 48 into the dust laden heavy oil 
in furnace inlet line 40. The steam increases the velocity of the dust 
laden heavy oil passing through the furnace tubes and passageways to 
minimize coking and buildup of carbon residue in the furnace tubes and 
passageways which would otherwise limit, restrict and/or block the passage 
of dust laden heavy oil through furnace 38. Preferably, superheated steam 
is injected into furnace inlet line 40 at a temperature of 500.degree. F. 
and at a pressure of at least 400 psig. 
Furnace 38 heats the dust laden heavy oil to a temperature in the range 
from 800.degree. F. to slightly below the retorting temperature in 
pyrolysis drum 16, preferably to 850.degree. F. Preheating the dusty oil 
before it is fed to pyrolysis drum 16 decreases the temperature gradient 
(thermal difference) between the hot heat carrier balls and cooler dusty 
oil when they are mixed in pyrolysis drum 16. A high temperature gradient 
can cause thermal shock which can crack, fracture and rupture the heat 
carrier balls. 
Preheating the dusty oil in furnace 38 also enhances the thermal efficiency 
of the system. If the dusty oil were not preheated before being fed into 
pyrolysis drum 16, greater quantities of heat from the heat carrier balls 
would be required to heat the dusty oil to the retorting temperature, 
which would necessitate greater quantities and feed rate of balls or 
preheating the balls to a much greater temperature. Increasing the 
quantity and flow rate of balls is not only expensive but decreases shale 
throughput and retorting efficiency. Increasing the temperature of the 
balls can cause substantial carbonate decomposition of the oil shale. 
Therefore, preheating dusty oil in furnace 38, minimizes the amount, rate 
and temperature of the balls being fed through retort 18. 
Furnace 28 is kept at a pressure to maintain the heavy oil in a liquid 
phase and minimize the vapor phase. The temperature in furnace 38 is kept 
below the retorting temperature in pyrolysis drum 16 to minimize thermal 
cracking of the heavy oil in furnace 38 as well as in lines 42, 46 and 20. 
The dust laden heavy oil is heated in the pyrolysis drum 16 and accumulator 
21 of retort 18 to the retorting temperature when mixed with the hot heat 
carrier balls to thermal crack and upgrade the heavy oil. From 80% to 100% 
and preferably at least 90% of the heavy oil in the dust laden heavy oil 
is thermal cracked into more marketable lighter oils and medium oils. The 
light and medium oils are withdrawn from accumulator 21 with the effluent 
product stream through overhead line 30. The thermal cracked heavy oil 
residue forms a coked material having a higher concentration of dust than 
the initial solids bottom fraction and contains less than 20% and 
preferably less than 10% uncracked heavy oil. The residual coked material 
is removed from accumulator 20 through solids discharge line 28. 
Referring now to FIG. 2, the process 110 shown in FIG. 2 is similar in many 
respects to the process 10 shown in FIG. 1. For ease of understanding and 
for clarity, similar parts and components of process 110 (FIG. 2) have 
been given part numbers similar to the parts and components of process 10 
(FIG. 1) except in the 100 series, such as furnace 138, steam injector 
148, etc. 
In process 110, a mixture of spent shale and spent residual material 
provides the solid heat carrier material. Sand can also be used. The heat 
carrier material is fed through heat carrier line 114 at a temperature 
from 1000.degree. F. to 1400.degree. F., preferably from 1200.degree. F. 
to 1300.degree. F., into screw conveyor 117 of retort 118 to mix with, 
heat and retort raw oil shale in screw conveyor 117. 
Raw or fresh oil shale is crushed and sized to a maximum fluidizable size 
of 10 mm by conventional crushing and screening equipment and fed through 
fresh shale inlet line 120 into screw conveyor 117 at a temperature from 
ambient temperature to 600.degree. F. 
Screw conveyor 117 mixes the fresh oil shale and solid heat carrier 
material together and discharges the mixture into surge bin 119 of retort 
118. Retorting of the fresh oil shale commences in screw conveyor 117 and 
is completed in surge bin 119. The retorting temperature of screw conveyor 
117 is from 850.degree. F. to 1000.degree. F. and preferably about 
960.degree. F. at atmospheric pressure. The solids residence time in screw 
conveyor 117 is from 6 seconds to 8 seconds. The solids residence time in 
surge bin 119 is from 5 minutes to 10 minutes. 
During retorting, an effluent product stream of hydrocarbons is liberated 
from the fresh oil shale as a gas, vapor, mist, or liquid droplets and 
most likely, a mixture thereof, along with entrained particulates of shale 
dust. The effluent product stream mixed with entrained particulates of 
shale dust is removed from surge bin 119 through overhead line 127 and 
partially dedusted in a cyclone 129 before being fed to separator 132 via 
separator inlet line 130. Steam from steam injector 134 can also be 
injected into surge bin 119 to minimize coking and buildup of carbon 
residue in overhead lines 127 and 130. Separator 132, pump 136, steam 
injector 148, furnace 138, pressure control valve 144, and lines 140, 142 
and 146 operate in the same manner as those components operate in FIG. 1. 
Furnace 138 heats the dust laden heavy oil to a temperature from 
800.degree. F. to a temperature below the retorting temperature of screw 
conveyor 117, preferably from 850.degree. F. to 950.degree. F. and most 
preferably 900.degree. F. While heating the dust laden heavy oil in 
furnace 138 is not necessary to avoid thermal shock of the solid heat 
carrier material inasmuch as spent shale is used instead of balls, 
preheating the dust laden heavy oil in furnace 138 does enhance thermal 
efficiency and reduce the quantity, rate and temperature of the heat 
carrier material fed into the retort as explained above. 
The dust laden heavy oil is thermal cracked and upgraded in retort 118 by 
mixing the dusty heavy oil with the solid heat carrier material in screw 
conveyor 117 and surge bin 119. The product yield and recovery are similar 
to the process of FIG. 1. 
The residual coked material, retorted shale and heat carrier material are 
removed from surge bin 119 through solids discharge outlet 128 and 
conveyed by gravity flow through combustor inlet line 150 into a vertical 
combustion lift pipe 156. Dust removed by cyclone 129 is discharged 
through cyclone discharge line 152 and also fed into combustor inlet line 
150. 
Air is injected through air injector 154 into the bottom of lift pipe 156 
to fluidize, entrain, mix, propel and convey the residual coked material, 
retorted shale, heat carrier material and cyclone dust, upwardly to a 
collection and separating bin 158, also referred to as a "collector." 
Carbon residue contained in the coked residual material and in the 
retorted shale is combusted in lift pipe 156 at a temperature from 
1000.degree. F. to 1400.degree. F. and preferably from 1200.degree. F. to 
1300.degree. F. leaving spent residual material and spent shale, 
respectively, which are recycled into retort 118 via heat carrier line 114 
with the reheated spent shale as solid heat carrier material. The 
combustion gases and products of combustion are removed through an 
overhead outlet line 160 and dedusted in cyclone 162 before being 
discharged. 
While the delayed coking and heavy oil dedusting process of this invention 
is particularly useful with the retorts described above, it can also be 
used with other retorts such as fluid bed retorts. The delayed coking and 
dedusting process can also be used to remove particulates of dust from 
whole oil at somewhat higher pressures. 
Among the many advantages of the process of this invention are: 
1. Improved quality and quantity of product yield. 
2. Less coking of lines. 
3. Better dedusting of the bottom heavy oil fraction. 
4. Lower product viscosity. 
5. Upgrading and purification of heavy oil. 
6. Ability to pipeline the dedusted oil through valves, outlet orifices, 
heat exchangers, pumps and distillation towers and refine the dedusted oil 
in hydrotreaters and catalytic crackers. 
7. Decreased erosion of equipment. 
8. Less wastage. 
9. Reduced downtime. 
Although embodiments of this invention have been shown and described, it is 
to be understood that various modifications and substitutions, as well as 
rearrangements or combinations of process steps, can be made by those 
skilled in the art without departing from the novel spirit and scope of 
this invention.