(en)The invention relates to a method for the continuous obtention of synthesis gas by the direct gasification of carbon fractions contained in oil sands and/or oil shales in a vertical process chamber ( 2 ) having a calcination zone and an oxidation zone ( 6 ), in which the calcinated, fractions rich in carbon oxidize with oxygen-containing gas. The gaseous reaction products are withdrawn at the top of the vertical processing chamber ( 2 ) that has the shape of a vertical shaft furnace which is continuously flown through from the top to the bottom by a bulk material which itself is not oxidized. Oxygen-containing gas ( 10 ) is at least partially introduced beneath the oxidation zone, whereby the rising gas flow is facilitated. The bulk material is at least partially provided by the natural inert rock content in the oil sands and/or the oil shales. Added alkaline substances convert under reductive conditions the gaseous sulfur compounds, which were obtained at temperatures above 400° C. from the constituents of the oil sands and/or the oil shales, by chemical reaction into solid sulfur compounds which are at least partially discharged with the gaseous reaction products and are removed from the gas phase at temperatures above 300° C. by fine material separation ( 18 ).

1.ApplicationNumber: US-201214005591-A
1.PublishNumber: US-2014014879-A1
2.Date Publish: 20140116
3.Inventor: STUMPF THOMAS
BOENKENDORF ULF
BAUMANN LEONHARD
MOLLER ROLAND

4.Inventor Harmonized: STUMPF THOMAS(DE)
BOENKENDORF ULF(DE)
BAUMANN LEONHARD(DE)
MOLLER ROLAND(DE)

5.Country: US
6.Claims:
(en)The invention relates to a method for the continuous obtention of synthesis gas by the direct gasification of carbon fractions contained in oil sands and/or oil shales in a vertical process chamber ( 2 ) having a calcination zone and an oxidation zone ( 6 ), in which the calcinated, fractions rich in carbon oxidize with oxygen-containing gas. The gaseous reaction products are withdrawn at the top of the vertical processing chamber ( 2 ) that has the shape of a vertical shaft furnace which is continuously flown through from the top to the bottom by a bulk material which itself is not oxidized. Oxygen-containing gas ( 10 ) is at least partially introduced beneath the oxidation zone, whereby the rising gas flow is facilitated. The bulk material is at least partially provided by the natural inert rock content in the oil sands and/or the oil shales. Added alkaline substances convert under reductive conditions the gaseous sulfur compounds, which were obtained at temperatures above 400° C. from the constituents of the oil sands and/or the oil shales, by chemical reaction into solid sulfur compounds which are at least partially discharged with the gaseous reaction products and are removed from the gas phase at temperatures above 300° C. by fine material separation ( 18 ).

7.Description:
(en)The invention relates to a method for continuous production of synthesis gas by direct gasification of carbon components, contained in oil sands and/or oil shales, in a vertical process chamber with a calcining zone and an oxidation zone, in which zone the calcined carbon-rich components oxidize with oxygen-containing gas, and the gaseous reaction products are drawn off at the top of the vertical process chamber, and the vertical process chamber is embodied in the form of a vertical shaft furnace, through which a bulk material, which itself is not oxidized, flows continuously from top to bottom, and the oxygen-containing gas is introduced at least partially below the oxidation zone, in that the bulk material, furnished at least partially by the natural inert rock component of the oil sands and/or oil shale, which is converted in the vertical process chamber by chemical reaction with the alkaline substances at temperatures of over 400° C. into solid sulfur compounds by adding alkaline substances under reductive conditions; these solid sulfur compounds are partially carried away with the gaseous reaction products; and at temperatures above 300° C. they are removed from the gas phase by fine-material separation.
Because of the strong worldwide demand for fossil fuels and petroleum-based raw materials, as well as the expected long-term scarcity of conventional petroleum, the recovery of energy carriers and raw materials from oil shale and/or oil sand resources is becoming increasingly important.
Naturally occurring oil sands or oil shale comprise natural rock and contain up to 20% of a bitumen mixture. This bitumen mixture essentially contains organic carbon compounds with different molecular weights and boiling points.
BACKGROUND OF THE INVENTION
To make these carbon compounds accessible to purposeful recovery, the bitumen mixture must first be separated from the natural rock component.
The separation of the bitumen from these natural rock masses can be done essentially via two technologies.
Recovery by open pit mining:
In this method, the rock mass containing bitumen is carried away using overburden dredgers or wheel loaders and transported to the processing plants with heavy road vehicles. The processing is done as a rule in the following process steps:
1. Breaking up/comminuting the rock, as a rule while supplying water vapor or hot water
2. Sending the resultant suspension to the first extraction step, where sediment and water form as the lower separation layer, and bitumen with foam forms as the upper separation layer.
3. Carrying away the lower sediment and water layer to usually artificial lakes or water lagoons.
4. Carrying away the upper bitumen layer to the second extraction step, where residues of water and fine particles are separated out. The bitumen is usually dissolved in an organic solvent (as a rule, “naphtha”, which is a product of the light-oil recovery process). What is obtained is so-called crude bitumen.
5. The crude bitumen is sent to ensuing bitumen processing (“upgrading”).
Recovery by the so-called “in-situ method”:
In this technology, the crude bitumen is already recovered in the soil, below the surface and without breaking up the rock masses. This is accomplished as follows:
6. High-pressure water vapor is injected into deep bitumen-containing rock strata. As a result, a thermal liquefaction of the crude bitumen is achieved.
7. This liquefied crude bitumen is carried purposefully into underground collection points and pumped from there to the surface, by means of suitable pumping technology.
8. The crude bitumen thus recovered then, as a rule, follows the same further procedure as in step 5 above.
Extraction of light oil and liquid fuels from crude bitumen:
The crude bitumen (possibly from both recovery methods) is combined in the next processing plant (“upgrading”). There, the following process steps are usually performed:
9. From the mixture comprising crude bitumen and naphtha, the volatile hydrocarbons are distilled off. At the end, what remains is an insoluble residue, called pet coke. Depending on the material used, it can contain up to 10% sulfur components.
10. The gaseous hydrocarbons from the distillation are separated by fractionated condensation into naphtha, kerosene, and gas oil; naphtha is as a rule at least partially returned to the process
11. Depending on the quality required of the individual fractions, desulfurization can be done in the further step. This is usually done by means of hydrogenation and separating out of the elemental sulfur.
12. At the end of the process come the storage and shipping out of the liquid fractions.
However, the method described above for recovering light oil and fuels from oil shale and/or oil sands has considerable disadvantages.
For instance, extracting the crude bitumen from the rock masses requires considerable amounts of hot water and water vapor. Per volumetric unit of light oil, up to 6 volumetric units of water have to be used. The preparation of steam and hot water is usually done in boilers fired by natural gas. The demand for natural gas is extremely high and leads to an extraordinarily unfavorable energy balance of the entire process. Moreover, as a result the specific CO 2 emissions per barrel of light oil obtained is fundamentally unacceptable ecologically and in view of the need to use valuable resources sparingly.
Despite efforts to circulate the water at least partially, the high water consumption of the method leads to a correspondingly high incidence of contaminated waste water. Because of the process, the waste water contains not only the sediment but above all residual concentrations of bitumen, polycyclic aromatics, also called PAH, and heavy metals. PAH is a mixture of aromatic organic substances of the most various molecular weights. In such PAH mixtures, toxic substances are as a rule highly prevalent as well. In particular, benzo(a)pyrene, which is suspected to be carcinogenic, must be mentioned.
These contaminated waste waters are usually deposited in artificial lakes or artificial lagoons. There, they present an extremely high risk of contamination to nature and the environment. In part, this affects the largest artificially created bodies of water in the world.
The pet coke remaining behind in the distillation of the crude bitumen (step 9) contains sulfur in concentrations of up to 10%. This is fundamentally a valuable energy carrier. However, because of its high sulfur content, it cannot readily be used in combustion processes, such as for generating water vapor or hot water. Ensuring environmentally sound thermal exploitation is therefore questionable and is possible, if at all, only at disproportionate expense for flue gas desulfurization.
For the present invention, the object has therefore arisen of furnishing a method which does not have the disadvantages of the prior art but permits environmentally appropriate and energy-efficient exploitation of carbon carriers contained in oil sands and/or oil shale without creating such great quantities of contaminated residues. At the same time, a method is to be furnished which handles fossil fuels (such as natural gas) sparingly, and which on its own can generate sufficient energy carriers to supply the requisite energy demand for the exploitation process.
According to the invention, in that by direct gasification of carbon components, contained in oil sands and/or oil shales, in a vertical process chamber with a calcining zone and an oxidation zone, in which zone the calcined carbon-rich components oxidize with oxygen-containing gas, and the gaseous reaction products are drawn off at the top of the vertical process chamber, and the vertical process chamber is embodied in the form of a vertical shaft furnace, through which a bulk material, which itself is not oxidized, flows continuously from top to bottom, and the oxygen-containing gas is introduced at least partially below the oxidation zone, this object is attained in that the bulk material, furnished at least partially by the natural inert rock component of the oil sands and/or oil shale, which is converted in the vertical process chamber by chemical reaction with the alkaline substances at temperatures of over 400° C. into solid sulfur compounds by adding alkaline substances under reductive conditions; these solid sulfur compounds are partially carried away with the gaseous reaction products; and at temperatures above 300° C. they are removed from the gas phase by fine-material separation ( 18 ).
In order to be able to gasify the carbon components contained in the oil sands or oil shales especially efficiently, it is advantageous to comminute the oil sands or oil shale, before their entry into the vertical process chamber, by means of mechanical energy to a particle size of less than 300 mm. As a result, the reactions proceeding in the vertical process chamber can be made especially efficient, since in this case the reaction surface area of the oil sands or oil shales is increased, yet at the same time sufficient gas permeability in the bulk material is ensured.
A further preferred embodiment of the method of the invention is that as the alkaline substances, metal oxides, metal carbonates, metal hydroxides or mixtures of two or three of these substances are used. These can be metered purposefully into the vertical process chamber or into the gas phase above the calcining zone. A further possibility is to admix metal oxides, metal carbonates, metal hydroxides or mixtures of two or three of these substances with the oil sands and/or oil shale before the entry into the vertical process chamber.
It has proved especially advantageous that the alkaline substances are used at least partially in fine-granular form, with a particle size of less than 2 mm as solid material and/or as a suspension in water.
A variant in which the metal oxides, metal carbonates, and metal hydroxides used contain elements of the alkaline earth metals and especially preferably contain calcium as a cation has proved especially preferable. Calcium here has the advantage the corresponding material used, calcium oxide, calcium carbonate or calcium hydroxide, have suitable physical and chemical material properties so as to attain virtually optimal outcomes in the present method with regard to binding the gaseous sulfur compounds. Moreover, the resultant sulfur compounds of the calcium are especially well suited for being separated off from the gas phase as a solid at a temperature of over 300° C.
Methods in the prior art until now often have considerably technical problems because of the formation of cleavage products that contain oil or tar. In the method of the invention, these problems are solved in that in the vertical process chamber and/or in the gas phase of the drawn-off gaseous reaction products in the presence of water vapor and calcium oxide and/or calcium carbonate and/or calcium hydroxide, a calcium-catalyzed reformation is performed at temperatures of above 400° C. In the process, essential components of the resultant cleavage products containing oil and/or tar, which have a chain length of greater than C4, are converted into carbon monoxide, carbon dioxide and hydrogen.
The requisite water vapor can be metered purposefully into the vertical process chamber and/or into the gas phase above the calcining zone. An embodiment in which the water vapor is furnished in situ from the residual moisture of the oil sands and/or oil shale is also advantageous. In that case, it may be possible to do without metering in water entirely.
The method of the invention can in principle also be performed in parallel with methods of the prior art described above for separating crude bitumen from the rock component of the oil sands or oil shales. In that case, as the water, aqueous media from the oil sand exploitation process, for instance from the extraction of the crude bitumen, can also advantageously be used for the calcium-catalyzed reformation.
To ensure an especially efficient form of the method of the invention, it is advantageous to remove as high a proportion as possible of the fine-granular alkaline substances and the solid sulfur compounds from the vertical process chamber via the gas phase. This is attained in that the flow speed of the gaseous reaction products drawn off at the top of the vertical process chamber, as a result of suitable process control, is furnished at at least 10 m/s and thus the removal of the fine-granular alkaline substances and the solid sulfur compounds from the vertical process chamber via the gas phase is in large part ensured.
For the success of the method of the invention, it is important that sufficient alkaline substances for binding sulfur products are furnished in the process. It has been demonstrated that the fine-granular alkaline substances must be used in a quantitative ratio of at least 1 g per Nm 3 of resultant gaseous reaction products, in order to attain good outcomes. As a result, a total dust concentration in the gas phase of the drawn-off gaseous reaction products of at least 1 g of solids per Nm 3 is ensured as well. This minimum dust concentration has proved necessary, to ensure a stable process for producing low-sulfur synthesis gas.
To separate the dust from the synthesis gas efficiently, it has provided advantageous to perform the fine-material separation of the fine-granular alkaline substances and the solid sulfur compounds from the gas phase is effected via stationary filter surfaces, on the oncoming flow side of which a coating of the solid filtration material forms as a deep filtration layer. As a result, a final intensive contact of the gaseous cleavage products with the fine-granular alkaline substances prior to the final fine-material separation is ensured, and thus a maximum amount of gaseous sulfur compounds is made to react with the alkaline substances and removed from the system.
The bulk material moving bed required for the method is formed at least in part by the rock component of the oils sands or oil shales used. Depending on the properties of the oil sands or oil shales, however, it can be advantageous to supplement the bulk material moving bed by additional metering in of coarse material, in order to increase the flowability of the bulk material and/or its gas permeability. This advantageously happens in that the coarse material is admixed with the oil sands or oil shale before entering the vertical process chamber.
It has been found that the method can be operated especially advantageously if as the coarse material, mineral substances and/or other inorganic substances or mixtures of substances having a particle size in the range of 2 mm to 300 mm are used. Equally good outcomes are achieved if as the coarse material, wood and/or other biogenic materials having a particle size in the range of from 2 mm to 300 mm are used.
An important actuating variable for the operation of the method is the metered amount of the oxygen-containing gas and of the resultant total lambda. The process is performed under reductive overall conditions, and a total lambda of less than 0.5 is established through all the stages of the process chamber. Preferably, the method can also be operated with a total lambda of 0.3 or less.
Depending on the bitumen content of the oil sands or oil shales used, it can be appropriate to increase the calorific value by adding further carbon carriers. This can advantageously be done in that such carbon carriers are admixed with the oil sands or oil shale before entering the vertical process chamber.
In order to ensure the move uniform possible flow of the bulk material through the vertical process chamber, the oxygen-containing gas can be delivered to the vertical process chamber in the form of pressure pulses. The mechanical forces thus generated contribute to loosening up and/or reinforcing the flow of the bulk material. These pressure pulses can for instance be tripped at regular intervals, so that bridges or clogs are prevented from forming in the bulk material at the very outset.
The method of the invention has the advantage that the crude bitumen contained in the oil sands/oil shales no longer needs to be isolated from the rock material using complicated, environmentally burdensome separation methods; instead, in a single method step, it can be converted especially efficiently and environmentally acceptably into a high-value synthesis gas, substantially comprising carbon monoxide, hydrogen, and low hydrocarbons. It is a particular advantage that the synthesis gas thus obtained is very pure and low in sulfur and as a result can be made available for many other processes. For instance, it is possible to convert the synthesis gas into the most various hydrocarbons, or also liquid fuels, by employing Fischer-Tropsch synthesis. This embodiment is also highly advantageous because the sediment and waste water that otherwise occur in the separation of the crude bitumen, or the pet coke that otherwise occurs, are because of the method not created in the first place; instead, a complete conversion of all the organic components of the oil sands/oil shale into synthesis gas can be accomplished.


FIG. 1 shows one exemplary embodiment of the method of the invention. This is intended to explain the method, but not to limit its scope.
The oil sands or oil shale (A) recovered by open pit mining are comminuted via breaker systems ( 1 ) mechanically to a particle size of less than 30 cm and delivered from the top, via a vertical chute, to a countercurrent gasifier ( 2 ), which is embodied as a vertical process chamber. The bulk material is formed entirely or in part by the rock component from the oil sand/oil shale (A). Depending on the quality and the physical nature of the oil sands or the oil shale, it may be advantageous to mix in still more coarse material ( 3 ), with a particle size of 2 mm to 300 mm, with the bulk material. This is especially appropriate whenever the flow behavior or the gas permeability of the bulk material needs to be improved.
Still other carbon carriers ( 4 ) can be mixed in with the bulk material to increase the proportion of exploitable carbon in the bulk material. Besides wood and biogenic substances, many extremely various carbon carriers can also be used. For instance, even residues that occur in the exploitation heretofore of oil sands or oil shales. In particular, this can be bitumen-containing sediments or pet cokes.
The mixture of bulk material, coarse material and residues flows through the vertical process chamber ( 2 ) by gravity from top to bottom. The countercurrent gasifier has burner lances ( 5 ) in its middle region, which ensure a basic load firing in he vertical process chamber and the steady development of a burning zone ( 6 ). These burner lances can be operated with fossil fuels ( 7 ) and oxygen-containing gas ( 8 ). Alternatively to the fossil fuels, synthesis gas from the countercurrent gasifier ( 9 ) can also be employed.
At the lower end of the vertical process chamber, oxygen-containing gas ( 10 is introduced. This gas serves first to cool down the bulk material in a cooling zone ( 11 ) before it leaves the vertical process chamber. The oxygen-containing gas is thus preheated as it continues to flow upward in the vertical process chamber. On the countercurrent gasification principle, the oxygen from the oxygen-containing gas reacts with the carbon-containing materials in the bulk material by oxidation, and the quantity of oxygen-containing gas is adjusted such that a total lambda of less than 0.5 is established in the vertical process chamber. As a result, first a burning zone ( 6 ) is formed, in which residues of the carbon-containing material react with oxygen to form CO 2 . Farther upward in the process chamber, the oxygen decreases further, so that finally, only low-temperature carbonization can occur, until still farther upward, all the oxygen is finally consumed, and a pyrolysis zone ( 12 ) forms under entirely reductive conditions.
Conversely, if one looks at the flow of the bulk material mixture comprising oil sands/oil shales, bulk material and alkaline substances from top to bottom, what happens first in the pyrolysis zone ( 12 ) is drying of the typically moist materials used, until an intrinsic temperature of 100° C. is reached. After that, the intrinsic temperature of the materials rises further, causing the gasification process to begin, and at an intrinsic temperature of up to 500° C., the formation of methane, hydrogen and CO begins. After extensive degassing, the intrinsic temperature of the materials increases further because of the hot gases rising from the burning zone ( 6 ), so that finally, the carbon-containing materials are entirely degassed and now comprise nothing but residual coke, so-called pyrolysis coke, and ash components. The pyrolysis coke is transported with the bulk material farther downward in the vertical process chamber, where it is converted partly into CO at temperatures above 800° C. with the CO 2 components from the burning zone by Boudouard conversion and likewise gasified. Some of the pyrolysis coke also reacts in this zone by the water-gas reaction with water vapor, which is likewise present in the hot gases, forming CO and hydrogen. Finally, at temperatures below 1800° C., residues of the pyrolysis coke are practically completely combusted and thermally utilized in the burning zone ( 6 ) along with the oxygen-containing gas flowing in from below. As a result, it is possible for the countercurrent gasifier to be supplied with virtually all the energy needed for the gasification. This is also known as an autothermal gasification process.
Water ( 13 ), as an additional cooling and gasification medium, can also be metered into the cooling zone via water lances ( 14 ).
The synthesis gas formed in the vertical process chamber is extracted at the upper end by suction ( 15 ), so that in the upper gas chamber ( 16 ), a slight underpressure of from 0 to 200 mbar is established.
Depending on the quality of the substances used, considerably amounts of gaseous sulfur compounds can occur during the gasification process. It is therefore advantageous if alkaline substances ( 16 ) are admixed with the oil sands/oil shales and the bulk material before they enter the vertical process chamber. For this purpose, metal oxides, metal hydroxides, or metal carbonates are especially suitable, and the use of fine-granular calcium oxide is especially preferred, since because of its reactivity and large surface area it reacts spontaneously with the gaseous sulfur compounds formed and thereby forms solid sulfur compounds, which are quite predominantly removed from the vertical process chamber together with the synthesis gas that is extracted by suction. Still other contaminants, such as chlorine, hydrogen chloride, or even heavy metals, can be bound highly effectively to the CaO and removed from the process in the same way.
Additionally, it can be appropriate to use coarse-granular metal oxides, metal hydroxides or metal carbonates as bulk material ( 3 ), in order on the one hand to increase the proportion of bulk material to the carbon-containing materials and on the other also to make alkaline reaction partners available in the lower part of the vertical process chamber for binding the gaseous sulfur compounds.
The synthesis gas extracted by suction contains dust, which essentially comprises the solid sulfur compounds, fine-granular alkaline substances, other contaminants, and inert particles. This synthesis gas containing dust can be treated in the gas chamber ( 16 ) of the vertical process chamber, or after leaving the vertical process chamber at ( 15 ), in the presence of water vapor and fine-granular calcium oxide at temperatures of over 400° C. This temperature can be established by suitable adjustment of the quantity of oxygen-containing gas ( 10 ) at the lower end of the vertical process chamber or by means of the calorific output of the burner lances ( 14 ) in the burning zone. However, it is especially advantageous to use direct fining in the synthesis gas via burner lances ( 17 ), which are operated stoichiometrically with fuel and oxygen-containing gas or even with an excess of oxygen-containing gas. This thermal posttreatment in the presence of water vapor and calcium oxide ensures that the oils and tars still present in the synthesis gas will be split off by the catalytic action of the calcium oxide.
The dust-containing synthesis gas is then freed of dust at temperatures above 300° C. by way of hot-gas filtration ( 18 ). The filter dust ( 19 ) containing sulfur is spun out of the process and either disposed of or put to an alternative use. In a preferred embodiment of the method, it is also possible to mix the filter dust, at east partially again as fine-granular alkaline substances, with the bulk material at ( 16 ) and thereby to operate in a partly circulatory mode.
The resultant synthesis gas ( 9 ) is practically sulfur-fee and can be used as fuel in the boiler systems ( 3 ).
Depending on conditions on site or on the requirements of the boiler systems, it may be necessary to cool down the synthesis gas using gas coolers ( 20 ) and to free it of condensates, before its exploitation can be done. The condensate ( 21 ) that occurs can be used again at least partially as a cooling and gasification medium via the water lances ( 14 ) in the vertical process chamber.
The bulk material mixture ( 22 ) emerging at the lower end of the vertical reaction chamber essentially contains coarse-granular bulk material, residues of ash, and fine-granular bulk material. The fine-granular bulk material can still contain small amounts of sulfur products and other contaminants.
The entire bulk material stream can be stored ( 23 ) in its entirety. However, it is especially preferable to screen the bulk material mixture ( 24 ); the coarse fraction ( 25 ) can preferably be put at least partially into circulation and used again as bulk material in the vertical process chamber at ( 3 ).
The fine screened fraction ( 26 ), together with the filter dust ( 19 ) that contains sulfur, is spun out of the process and disposed of or put to an alternative use. Here again, it is possible in a preferred embodiment of the method to mix the fine screened fraction at least partly again as fine-granular alkaline substances with the bulk material at ( 16 ) and thereby operate with at least partial circulation of the fine screened fraction.