Patent Application
20200385638
Many processes have been developed for producing hydrocarbons from various hydrocarbonaceous materials such as oil shale and tar sands. Generally, methods for recovering hydrocarbon products from oil shale have involved applying heat to the oil shale. Heating oil shale allows kerogen in the oil shale to break down through the process of pyrolysis, yielding liquid and vapor hydrocarbon compounds. Although some processing techniques and equipment have improved performance, operating costs, maintenance, and processing continue to present challenges which are difficult to overcome.
A radial flow oil shale retort can include a central heating fluid conduit having a permeable outer wall. An outer heating fluid annulus can be positioned about the central heating fluid conduit, the outer heating fluid annulus having a permeable inner wall. An annular body of comminuted oil shale can be between the permeable outer wall of the central heating fluid conduit and the permeable inner wall of the outer heating fluid annulus. A heating fluid supply can be connected to either the central heating fluid conduit or the outer heating fluid annulus to flow a heating fluid in a radial direction through the annular body of comminuted oil shale.
In one example, the heating fluid supply is connected to the central heating fluid conduit to flow the heating fluid in a direction from the central heating fluid conduit to the outer heating fluid annulus. In yet another example, the heating fluid supply is connected to the outer heating fluid annulus to flow the heating fluid in a direction from the outer heating fluid annulus to the central heating fluid conduit. In further examples, the retort can include a catalytic heater in the central heating fluid conduit or in the outer heating fluid annulus, wherein the catalytic heater produces heat by a chemical reaction of hydrocarbons in the heating fluid.
The retort can also include a rotary shale distributor positioned above the annular body of comminuted oil shale to distribute oil shale between the permeable outer wall of the central heating fluid conduit and the permeable inner wall of the outer heating fluid annulus.
In a particular example, the heating fluid comprises steam and in most cases is predominately steam. In another example, the heating fluid comprises hydrocarbons and in most cases is predominately hydrocarbons. In yet another example, the heating fluid comprises oxygen and/or mixtures of gases containing at least some percentage of oxygen.
The retort can also include a combustor unit and a shale withdrawal conduit to convey spent shale to the combustor, wherein the combustor generates heat by combusting the spent shale. In certain examples, the combustor is a fluid bed combustor or a down flow bed combustor. In other examples, the retort can include a vapor/gas product outlet connected to either the central heating fluid conduit or the outer heating fluid annulus, whichever is not connected to the heating fluid supply. In still other examples, the retort can include a liquid product outlet in fluid communication with the annular body of comminuted oil shale to collect liquid hydrocarbon products produced from the comminuted oil shale.
In yet other examples, the retort can include a heating unit connected to the heating fluid supply to heat the heating fluid before the heating fluid flows through the annular body of comminuted oil shale. In further examples, the dimensions of the retort can include the diameter at the outer walls of the retort from 10 feet to 100 feet or about 40 feet; the diameter at the permeable inner wall of the outer heating fluid annulus from 9 feet to 90 feet or about 38 feet; the diameter at the permeable outer walls of the central heating fluid conduit from 1 foot to 10 feet or about 6 feet; a bed depth measured from the permeable outer wall of the central heating fluid conduit to the permeable inner wall of the outer heating fluid annulus from 1 foot to 80 feet or about 16 feet; a bed height measured in the axial direction of the retort from 10 feet to 300 feet.
A complimentary method of extracting hydrocarbons from oil shale can include loading comminuted oil shale into a radial flow oil shale retort, wherein the radial flow oil shale retort comprises: a central heating fluid conduit having a permeable outer wall, and an outer heating fluid annulus positioned about the central heating fluid conduit, the outer heating fluid annulus having a permeable inner wall, wherein the comminuted oil shale is loaded into a space between the permeable outer wall of the central heating fluid conduit and the permeable inner wall of the outer heating fluid annulus. A heating fluid can flow in a radial direction between the central heating fluid conduit and the outer heating fluid annulus to heat the comminuted oil shale and extract hydrocarbons therefrom, and the hydrocarbons can be collected.
In some examples, the comminuted oil shale is substantially stationary during the extraction of the hydrocarbons, and further comprising loading and unloading the comminuted oil shale from the retort, such that the process is a batch process. In other examples, the comminuted oil shale continuously flows through the retort such that the process is continuous. In certain examples, the method can include continuously loading comminuted oil shale into the retort and continuously withdrawing spent oil shale from the retort. Where the shale is flowing in an annulus, the rate of flow can be a function of the dimensions, and the rate of heating the shale to retort temperature. Flow rate is also a function of the recirculation of the heating medium and composition of the heating medium that transfer heat to the cold shale. In a particular example, the comminuted oil shale can flow downward at a speed of 1 inch per hour to 10 feet per hour.
There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with the accompanying drawings and claims, or may be learned by the practice of the invention.
These drawings are provided to illustrate various aspects of the invention and are not intended to be limiting of the scope in terms of dimensions, materials, configurations, arrangements or proportions unless otherwise limited by the claims.
While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the present invention. Thus, the following more detailed description of the embodiments of the present invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the present invention, to set forth the best mode of operation of the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the present invention is to be defined solely by the appended claims.
In describing and claiming the present invention, the following terminology will be used.
As used herein, “hydrocarbonaceous material” refers to any hydrocarbon-containing material from which hydrocarbon products can be extracted or derived. For example, hydrocarbons may be extracted directly as a liquid, removed via solvent extraction, directly vaporized, by conversion from a feedstock material, or otherwise removed from the material. Many hydrocarbonaceous materials contain kerogen or bitumen which is converted to a flowable or recoverable hydrocarbon through heating and pyrolysis. Hydrocarbonaceous materials can include, but are not limited to, oil shale, tar sands, coal, lignite, bitumen, peat, and other organic rich rock. Thus, existing hydrocarbon-containing materials can be upgraded and/or released from such feedstock through a chemical conversion into more useful hydrocarbon products. Chemical conversion can include synthesis reactions, decomposition reactions or other reactions which result in chemically distinct product compounds. Such chemical conversions can be accomplished thermally, catalytically, and/or via addition of other chemical components.
As used herein, “spent hydrocarbonaceous material” and “spent oil shale” refer to materials that have already been used to produce hydrocarbons. Typically after producing hydrocarbons from a hydrocarbonaceous material, the remaining material is mostly mineral with the organic content largely removed. In some cases, spent oil shale can have a sufficient amount of residual hydrocarbon or carbon content that the spent oil shale can be burned in a combustor to generate additional heat.
As used herein, “lean hydrocarbonaceous material” and “lean oil shale” refer to materials that have a relatively low hydrocarbon content. As an example, lean oil shale can typically have from 1% to 8% hydrocarbon content by weight.
As used herein, “rich hydrocarbonaceous material” and “rich oil shale” refer to materials that have a relatively high hydrocarbon content. As an example, rich oil shale can typically have from 12% to 27% hydrocarbon content by weight, and some cases higher.
Many examples described herein involve processing of oil shale. In some cases, these examples can also be made and used with other types of hydrocarbonaceous material other than oil shale.
As used herein, whenever any property is referred to that can have a distribution between differing values, such as a temperature distribution, particle size distribution, etc., the property being referred to represents an average of the distribution unless otherwise specified. Therefore, “particle size of the comminuted oil shale” refers to an average particle size, and “temperature of the body of comminuted oil shale” refers to an average temperature of the body of comminuted oil shale.
It is noted that, as used in this specification and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a layer” includes one or more of such features, reference to “a particle” includes reference to one or more of such elements, and reference to “producing” includes reference to one or more of such steps.
As used herein, the terms “about” and “approximately” are used to provide flexibility, such as to indicate, for example, that a given value in a numerical range endpoint may be “a little above” or “a little below” the endpoint. The degree of flexibility for a particular variable can be readily determined by one skilled in the art based on the context. However, unless otherwise enunciated, the term “about” generally connotes flexibility of less than 2%, and most often less than 1%, and in some cases less than 0.01%.
As used herein, the term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, the nearness of completion will generally be so as to have the same overall result as if absolute and total completion were obtained. “Substantially” refers to a degree of deviation that is sufficiently small so as to not measurably detract from the identified property or circumstance. The exact degree of deviation allowable may in some cases depend on the specific context. The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.
As used herein, “adjacent” refers to the proximity of two structures or elements. Particularly, elements that are identified as being “adjacent” may be either abutting or connected. Such elements may also be near or close to each other without necessarily contacting each other. The exact degree of proximity may in some cases depend on the specific context. Additionally, adjacent structures or elements can in some cases be separated by additional structures or elements between the adjacent structures or elements.
As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary.
Concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted to include not only the explicitly recited limits of 1 to about 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than about 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described.
Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. Means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; and b) a corresponding function is expressly recited. The structure, material or acts that support the means-plus function are expressly recited in the description herein. Accordingly, the scope of the invention should be determined solely by the appended claims and their legal equivalents, rather than by the descriptions and examples given herein.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended. Additional features and advantages of the technology will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the technology.
With the general examples set forth in the Summary above, it is noted in the present disclosure that when describing the system, or the related devices or methods, individual or separate descriptions are considered applicable to one other, whether or not explicitly discussed in the context of a particular example or embodiment. For example, in discussing a device per se, other device, system, and/or method embodiments are also included in such discussions, and vice versa.
Furthermore, various modifications and combinations can be derived from the present disclosure and illustrations, and as such, the following figures should not be considered limiting.
In various examples, radial flow oil shale retorts can have any combination of the following features. In some examples, the retort can operate as a batch process or a continuous process. As a batch process, the retort can be filled with comminuted oil shale, then the oil shale can be heated for a period of time to extract hydrocarbons therefrom, and then the spent oil shale can be removed from the retort either after a cooling step or while the spent shale is cooling. As a continuous process, the oil shale can be a moving bed. Fresh oil shale can be continuously or periodically introduced at the top of the retort and spent oil shale can be withdrawn from the bottom of the retort. Suitable filling and withdrawing equipment can be used, such as lock hoppers, oil shale distributors, feed pipes, withdrawal tubes, and so on.
As a general guideline, the heating fluid as a working fluid can flow in a radially inward direction or in a radially outward direction through the bed of oil shale. With inward flow, the heating fluid can be introduced into an outer heating fluid annulus around the bed of oil shale. The heating fluid can then flow in an inward direction through the bed of oil shale and into a central heating fluid conduit. With outward flow, the heating fluid can flow in the opposite direction.
The oil shale can be contained in an annular space with permeable walls to allow heating fluid to flow through particulate or crushed oil shale. The outer heating fluid annulus can include a permeable inner wall. The inner heating fluid conduit can also include a permeable outer wall. In some examples, the permeable walls can be rigid walls with holes perforating the walls, mesh baskets, layers of mesh or screen material, profile wire screen, or any other type of permeable wall that can allow heating fluid to pass through while maintaining the comminuted oil shale in the bed.
During processing, the retort can be heated by a heating fluid that is heated by an external heat source and supplied to the retort at the desired heating temperature. The heating fluid can include hydrocarbon gases, hydrocarbon vapors, steam, hot air, oxygen, and other fluids in any mixture or ratio. In one optional example, oxygen content in the heating fluid can be less than about 21%. In some cases, the working fluid can be provided by a dedicated burner. Optionally, or in addition, the working fluid can be gaseous and vapor products recovered from another adjacent retort. For example, non-condensed hydrocarbon product mixed with a heating fluid can be introduced into the retort as a working fluid.
In other examples, the retort can include a catalytic heater that can generate heat by reaction of hydrocarbons with oxygen. In certain examples, the heating fluid can include hydrocarbons and oxygen and the heating fluid can flow past or through a catalytic heater in the retort (or outside the retort before the heating fluid enters the retort) to generate heat to heat the heating fluid. Combinations of these heating methods can be used, such as catalytic heating with supplemental steam heating, preheating hydrocarbon gases before further heating the gases using a catalytic heater, and so on. In some examples, the temperature of the heating fluid can be from 800° F. to 1000° F. Non-limiting examples of catalytic converter materials can include zeolites, heterogeneous catalysts, and the like. With these somewhat general principles in mind, the following specific examples, illustrate various more detailed implementations which can be utilized.
Within the retort body 106, the oil shale can be directed into an annular body of comminuted oil shale 114 between an outer heating fluid annulus 116 and a central fluid conduit 118. In this particular example, the outer heating fluid annulus 116 and central fluid conduit 118 can be constructed as profile wire screens, e.g. as a Johnson screen, although any perforated barrier may be used which prevents comminuted oil shale from passing through while also allowing gases and liquids to pass. The bottom of the retort 120 can be lined with abrasion resistant refractory material.
Heating fluid (working gas) 122 can be introduced into the retort body at a heating fluid inlet 124. In one specific example, the working gas can be supplied at 800° F. to 1000° F. and flows in through a 36 inch to 55 inch heating fluid inlet 124 in the retort body 106. The heating fluid flows into an upper header portion 126 and then into the outer heating fluid annulus 116 oriented between the retort vessel wall 128 and the permeable inner wall 130. The heating fluid then passes inwardly through the annular bed 114 of oil shale and through a permeable outer wall 132, and into the central heating fluid conduit 118. The heating fluid flows from the central heating fluid conduit 118 to a fluid outlet 134 at the bottom of the retort. In one example, the fluid outlet can be a 60 inch to 72 inch outlet.
As the heating fluid flows through the annular shale bed 114, hydrocarbons are removed from the oil shale or other carbonaceous material and carried with the predominate quantity of heating fluid. This means that at the exit, the heating fluid is mixed with gaseous and vapor hydrocarbon products extracted from the oil shale. Spent oil shale is withdrawn from the bottom of the retort through one or more spent shale outlets 136. In one example, spent shale outlets can include a pair of six vane lock hopper valves 138 with an optional intermediate purge 140. In one specific example, the spent shale outlets may be 20 inch shale withdrawal tubes leading to a pair of six vane hopper valves.
Spent shale can be sent to a shale combustor to combust residual carbonaceous material to generate heat which can be used in other portions of the process (e.g. in a preheating cycle of an adjacent retort). Although dimensions can vary considerably based on design criteria and desired throughput, in one specific example, the retort vessel inner diameter can be 40 feet, the basket permeable inner wall diameter can be 38 feet, the permeable outer walls diameter can be 6 feet, the bed depth (horizontal distance between the basket and center pipe walls) can be 16 feet, while the bed height can be from 40 feet to 300 feet. The capacity of such a dimensioned retort can be about 276 tons of oil shale per hour and the corresponding yield can be about 3400 barrels per day of produced hydrocarbon product. Of course other specific dimensions can be designed for specific production parameters and these specific dimensions are provided merely as one example.
Spent shale from radial flow retort 100 can be sent to a combustor 202. This spent shale can be injected directly into the combustor 202, or in an alternative, a set of six vane rotary lock hopper valves 204 can control flow of spent shale into a rotary distributor 206. The combustor 202 can operate to combust any residual kerogen, hydrocarbons or other materials in order to produce a flue gas. As non-limiting examples, the combustor can be a fluid bed combustor or a down flow bed combustor. For example, a grate or other spent shale removal device 210 can be oriented in a bottom portion of the combustor and adapted to direct and move combusted spent shale toward a shale outlet 212. Combusted shale can then be disposed of and typically has a temperature less than about 400° F.
An air supply (e.g. or other oxygen supply source) can be directed into an air inlet at a bottom oxidizer inlet 214 via a suitable pump 216. An air distributor 218 can introduce the air supply into the combustor where combustion takes place to burn residual materials and produce the flue gas containing a recoverable heat value. The combustor flue gas can be removed from the combustor 202 via an upper combustor outlet 208 and directed to a heat exchanger 220. This heat exchanger 220 can be used to preheat incoming working fluid (e.g. often about 250° F.) to a preheated working fluid temperature of about 850-900° F. This working fluid can then be introduced into retort 106.
Cooled flue gas can then be directed to a scrubber 222 via pump 224 where SO2 can be removed. An optional ESP (electrostatic precipitator) 226 can further reduce particulates and dust prior to atmospheric venting via an exhaust stack 228.
Working gas and product removed from the radial flow retort 100 can be sent to a condenser or distillation column 230 via an optional ammonium injector and venturi scrubber 232. Column 230 can be used to condense and recover liquid hydrocarbon products via pump 234 to separator 236. Liquids removed from the column can be separated into ammoniated water and oil to storage. Final product oil can be sent to storage while ammonia can be reconditioned or recycled via pump 238 and cooler 240. Ammonia make up may be added to the working gas/hydrocarbon product stream and the stream may be sent to column 230. Ammonia make up and water make up (via water line 242) can also be fed into the column 230. Gas from the separator can be stored or recycled for use as the working gas in the retort. Non-condensed working fluid can then be recycled back to heat exchanger 220 via pump 244 or sent as net gas to treating and recovery. This working gas from column 230 typically has a temperature of only about 150 to 180° F., depending on particular operating conditions.
Optionally, a portion of flue gas from combustor 202 can be directed to a steam production unit 246 prior to introduction into scrubber 222 via pump 248. In this manner, steam can be produced from a water source. In some cases the flue gas can have a relatively high temperature of about 2400° F. such that produced steam may be used for driving a steam turbine (not shown) or for other uses.
The effluent from the radial retort 300 can be fed through a venturi scrubber 418 to a separator column 420 similar to the sub-system described above. Product hydrocarbon gas can be withdrawn from the top of the separator column 420 for treating and recovery. Liquid from the bottom of the separator can be further separated into ammoniated water and oil for storage. Other equipment in this example is similar to the example in
In one alternative example, the retort vessel can include one or more zones. For example, multiple zones can be created by providing divisions along the axial dimension of the outer heating fluid annulus 116. As a general guideline, the outer annulus can be divided into one or more sections where fluids of differing temperatures and/or compositions can be fed and simultaneously flow into the center pipe. For instance, a 60 ft long basket could be divided into two sections where the top section, e.g. 40 ft long, passes a hot fluid, e.g. 900° F., from the outer basket through downflowing shale and into the center pipe. An additional amount of fluid, e.g. cooler than that input to the top 40 ft section, can flow into the lower, e.g. 20 ft, annular area created by the lower 20 ft of outer basket. This cooler fluid also flows radially, contacting the downward flowing shale, ostensibly cooling the shale, and passing into the center pipe. In the center pipe this fluid combines with the fluid flowing from the topmost section and exits the retort as a commingled stream. Optionally, there may be small baffles to retard the flow of fluids between zones. Regardless, the zones are mostly created by the injection of the working fluid at different levels. Therefore, there can be a physical structure in the center or outer basket (e.g.
In one example, the retorting/removal of hydrocarbons and cooling of the spent shale is accomplished in a single vessel. In this example, it may not be desirable to combust the cooled, spent shale. The same operation can also be accomplished in separate vessels, namely one for retorting and one for cooling in a manner similar to that accomplished where the retorting and combustion of spent shale is accomplished in separate vessels.
In one optional aspect, recirculation of gas to different outer basket zones can be configured in parallel. One advantage of the radial flow approach is maintaining a similar pressure drop thru the bed in each zone, which can minimize leakage between the zones, so one can process shale at different conditions within the moving bed. The retort gas reheat temperature and flows to the different zones can be controlled by suitable piping, heating control, and splitting systems external to the retort. For example, in one alternative, a plurality of working fluid inlets can be oriented on a side of the retort body 106. In this manner, working fluid of different temperatures can be directed to each of the plurality of zones.
The described features, structures, or characteristics may be combined in any suitable manner in one or more examples. In the preceding description numerous specific details were provided, such as examples of various configurations to provide a thorough understanding of examples of the described technology. One skilled in the relevant art will recognize, however, that the technology may be practiced without one or more of the specific details, or with other methods, components, devices, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the technology.
The foregoing detailed description describes the invention with reference to specific exemplary embodiments. However, it will be appreciated that various modifications and changes can be made without departing from the scope of the present invention as set forth in the appended claims. The detailed description and accompanying drawings are to be regarded as merely illustrative, rather than as restrictive, and all such modifications or changes, if any, are intended to fall within the scope of the present invention as described and set forth herein.
This application claims priority to U.S. Provisional Application No. 62/857,016, filed Jun. 4, 2019 which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62857016 | Jun 2019 | US |
