Patent Application
20100150658
The invention relates to a process and system for treating oil-bearing media such as oil-contaminated soil, oil shale, oil sands, coal, and oil-bearing sludges of different types from oil producers, upgraders and refineries, in order to remediate the media or recover the oil.
Both low temperature thermal desorption (temperature ranging from 90 to 316° C.) and high temperature thermal desorption (temperature ranging from 316 to 427° C.) methods are commonly used to remove volatile and semi-volatile organics from a matrix material. These techniques are typically not effective in removing high boiling point organics such as coal tars or asphalt.
In contrast, pyrolysis (temperature greater than 430° C.) is a chemical decomposition of organic materials induced by heat in an inert environment and may be effective to remove high boiling point organics.
There are numerous examples in the prior art of thermal desorption systems that employ rotary dryers or kilns, high temperature belt conveyors and screw conveyors. Some of these systems also demonstrate both direct and indirect methods of heat transfer. Process conditions for these systems vary widely, with some utilizing vacuum to near atmospheric pressures for separating organic contaminants. All these methods use high cost fuels or energy, such as electricity, natural gas or oils, the cost of which appears to be rising long term.
For remediation of oil-contaminated soils, direct thermal process or incineration process is not a good option as some metals can be emitted to the air as pollutants at high temperature operation. In addition, the soils are sterilized completely and are not suitable for future cultivation.
Therefore, there is a need in the art for a system and method that permits thermal desorption of oil-bearing media, which may mitigate the difficulties of the prior art.
The present invention comprises a thermal treatment system and method which permits the flexibility to allow for the practice of low temperature thermal desorption, high temperature thermal desorption or pyrolysis, depending on the contaminated media or oil-bearing media to be treated, while operating with overall energy efficiency.
The system and method of the present invention may be used for oil production from oil shale, oil sands and coal. In one embodiment, it is possible to produce oil from oil shale, oil sands or coal without using water as an extraction solvent, both as a surface separation technology, or in situ.
The system and method may be used to remove organic and inorganic contaminants from solid media such as drill cuttings, tank bottoms or contaminated soils, using low temperature thermal desorption, high temperature thermal desorption or pyrolysis.
Therefore, in one aspect, the invention comprises a thermal remediation or oil production system for treating hydrocarbon bearing media, comprising:
In another aspect, the invention comprises a co-combustion burner for use with a thermal desorption system, said burner comprising:
In another aspect, the invention comprises a condensing system for condensing a mixture of volatile hydrocarbons, said system comprising:
In the drawings, like elements are assigned like reference numerals. The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental concepts of the present invention. The drawings are briefly described as follows:
The present invention relates to a portable or fixed thermal remediation/treatment system and method which have the flexibility, depending on the contaminated media or oil-bearing media to be treated, to allow for the practice of low temperature thermal desorption, high temperature thermal desorption or pyrolysis. Any term or expression not expressly defined herein shall have its commonly accepted definition understood by those skilled in the art.
As will be apparent to those skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the scope of the invention claimed herein. The various features and elements of the described invention may be combined in a manner different from the combinations described or claimed herein, without departing from the scope of the invention.
The hydrocarbon bearing media may comprise any solid material which bears or is mixed with a hydrocarbon or mixture of hydrocarbons. The hydrocarbon may comprise any light or heavy oil, or a hydrocarbon residue resulting from another process. Typical hydrocarbon bearing media which may be treated with embodiments of the present invention include, without limitation, oil-contaminated soil, oil shale, oil sands, coal, bitumen, and oil-bearing sludges of different types from oil producers, upgraders or refineries. Media to be treated with high moisture content is also tolerated, however, in one embodiment, moisture content is preferably below about 20%.
Exemplary embodiments of the present invention are described below with reference to the Figures.
The volatilized heavy and light oils are withdrawn from the twin desorption units using a suction fan and then condensed separately in a heavy component condenser followed by a light component condenser. The condensed light oils are separated from water in a three-phase (gas/oil/water) separation tank.
The raw material is fed into the trundles using a blender with air blowing capability to break down big lumps and reduce moisture, and a hammer crasher to break down the big rocks so that the material can be fed smoothly into the desorption unit. The material after treatment are discharged from the twin desorption unit.
The co-combustion burner is adapted to burn different types of fuels individually or in any combination. Suitable fuels include gases (butane, propane, or natural gas), liquids (natural gas liquids, condensates or used or waste oils) and solids (coke, asphaltenes, coal or scrap tires), sludges with high oil content or combinations thereof. The fuels may be loaded intermittently or continuously. In one embodiment, solid fuels are loaded intermittently, while the gas, liquid and sludge fuels are loaded continuously from respective storage tanks. The burner may also utilize tail gas which is not condensed during condensation and recovery of the hydrocarbon vapor produced from the desorption unit.
In one embodiment, the system is powered and controlled using conventional electrical controls for systems of this nature, which are well known to those skilled in the art. The system may comprises an electrical control room includes all electrical panels and controllers attached to or detached from the twin desorption unit and other elements of the system.
The feed hoppers convey material to the desorption unit, which is designed to convey, turn, mix, and indirectly heat the material during processing. Preferably, in one embodiment, the desorption unit is self-cleaning.
One embodiment of a twin desorption unit is shown in
Although the size of the trundle may be increased to allow greater capacity, the rate of heat transfer into the trundle is adversely affected. As the diameter of the trundle increases, the ratio of surface area to volume decreases. Also, as the size of the trundle increases, the trundle must be made of thicker material to maintain adequate strength, which also adversely affects heat transfer.
As used herein, a “trundle” means a rotating cylinder or drum, where material contained within the trundle is advanced through the trundle by rotation of the trundle. Material may be advanced by inclination of the trundle, or by mechanical means such as internal paddles, fins or bars. In one embodiment, each rotating trundle each comprises multiple space bars attached to the inner surface of the trundle, the space bars are 1-3 inches high and approximately 1-1.5 feet apart and deviate from the axis of rotation by an inclination ratio of about (0-2):100.
The volatilized gas oils and steam are withdrawn from each trundle through vapor outlets 23 with a suction fan 22 connected with a suction pipe 24, as shown in
As a result of the suction fan 22, the atmosphere in the trundle operates under a pressure slightly lower than atmospheric. This is advantageous in that it eliminates the need to seal the trundle, and to seal the housing it is contained in. The risk of leaking flammable or explosive gases is minimized as all hydrocarbon gases are sucked into the condensing system. The amount of vacuum pressure in the trundles and the housing may be varied by varying the speed of the suction fan 22.
A stop rim 31, shown in
In order to improve the durability of the trundles 15, two strength rims 36 may be attached to the external surface of each trundle at the locations where the wheels 37 contact the trundle. Each two of the wheels 37 are mounted on a wheel holder 38 in a fixed distance apart, the wheel holder is then mounted on the frame structure 39 supported by multiple legs 40 and its mounting location on the frame structure 39 is adjustable slightly for easy positioning of the trundles 15. The trundle is preferably maintained in a horizontal position to allow adequate support along the length of the trundle by the wheels, and to prevent gravity creep of the trundle off its supports.
The trundles 15 may be rotated by any suitable means, for example a chain drive mechanism. At the feeding hopper 14 side, each trundle 15 is rotated by a chain 41 which links one side to a sprocket 42 attached to the trundle, and another side to a reversible variable speed motor 43 shown in
The trundles are heated with hot exhaust from the co-combustion burners described below. To improve heat exchange, with reference to
As shown in
Both heavy and light components are volatilized into gas oils along with steam in the twin desorption unit. After being withdrawn by a suction fan 22, the volatilized gas oils and steam enter into a cooling line with a heavy component condenser 50 followed by a buffer tank 51, a light component condenser 52 and a three-phase separation tank 53. As shown in
The incoming stream of gas oils is aimed at the condensing dish at relatively high velocity. Heavy gas oils are condensed on the surface of the condensing dish 59 at a high impingement pressure created by the velocity of the incoming gas stream. Uncondensed light gas oils and steam will leave via the vapor outlet 56 for the light component condenser 52 for further condensation. The impingement pressure may be varied by tilting the dish at an angle, or moving it farther away from the vapor outlet. The ratio (measured by mass or volume) of the heavy components condensed to uncondensed light components in the heavy component condenser 50 can be changed significantly by adjusting the impingement angle of the condensing dish 59 using the handle 61, which will alter the impingement pressure created at the surface of the condensing dish. Alternatively, or additionally, the impingement pressure can be varied by moving the condensing dish 59 closer to or farther away from the incoming gas stream. The dish position can be adjusted by moving the dish holder 60 closer to or far from the vapor inlet 55. As may be appreciated by one skilled in the art, higher pressure is conducive to condensation of lighter components.
The heavy to light condensation ratio in the heavy component condenser 50 also changes when the operating temperature of the twin desorption unit changes. This means that the so called “heavy” or “light” is a relative concept, which is different from the conventional concept of heavy oil or light oil. Conventional heavy crude oil is any type of crude oil which does not flow easily. It is referred to as “heavy” because its density or specific gravity is higher than of light crude oil. Heavy crude oil has been defined as any liquid petroleum with an API gravity less than 20°, meaning that its specific gravity is greater than 0.933. Light oils and even water can be condensed in the heavy component condenser 50, especially, when the whole system starts or restarts and the twin desorption unit and the condensing elements have not yet reached their operating temperatures. Steam should not be condensed in the heavy component condenser 50 once its internal temperature reaches above about 110° C.
From the condensor 50, in one embodiment, the vapor stream continues to the buffer tank 51, provides additional volume for the volatilized vapors to avoid abrupt pressure fluctuation in the cooling line. The buffer tank 51 may not be necessary if the heavy condensor 50 is of sufficient volume relative to the flow rate of the system. Some minimal condensation of medium weight hydrocarbons may occur in the buffer tank 51 and a liquids outlet is provided.
As shown in
Light gas oils and steam are condensed in the vertical or inclined pipes 63 and flow down to the collection pipe 65, then to the three-phase separator 53. The try valve 66 may be used to visually check the performance of the condenser. The extent of the inline valve 67 opening may depend on the system operating temperature and the cooling performance of the light component condenser 52. The inline valve 67 should be open to the extent that no significant amount of liquid comes out of the try valve 66 when the try valve 66 is open. As a result, uncondensed vapor will go to the three-phase separator 53 primarily via the cooling pipe, while substantially all of the condensate will enter the three-phase separator (53) via the horizontal collection pipe.
The three-phase separator 53 receives uncondensed vapors from the end of cooling pipe 63 at the upper part, and liquid from the horizontal pipe 65 at the lower part. With sufficient residence time in the tank, gases dissolved in the liquid phase will be released and liquid hydrocarbons will separate from water. The remaining vapor or tail gas may be flared off, or may be recycled back to the co-combustion burners, through vapor outlet 69. Light oil and water are released intermittently via oil outlet 70 and water outlet 71, respectively.
The present invention comprises a high efficiency co-combustion burner that supplies heat to the desorption unit. As shown in
In the burner box 73, part or all of the volatiles and semi-volatiles of liquid fuels such as used or waste oils, solid fuels such as coal, coke or scrap tires and sludge fuels (sludges with high oil content) are converted into gas oils 78 (or smoke). The turbo chamber 74 creates a turbulent flow and mixes thoroughly the volatilized gas oils and additional air provided by the blower 77, and streams the mixture to the combustion chamber 75. Both the burner box 73 and the combustion chamber 75 are preferably insulated using high temperature insulation 79 such as cement mix or mineral wool.
A suitable fuel is introduced to the burner box 73 through inlet 85 located at the upper part and front side of the burner box. In reference to the Figures, the front side of the burner box is that side which faces the combustion chamber 74. The burner box 73 comprises a lid 86 with hinges hooked at one side so that the lid 86 can be opened when loading solids fuels and to perform maintenance. The lid may comprise a burner lid opener 87 to open the lid, and multiple spring latches 88 to hold the lid closed. The spring latches may act as a pressure relief mechanism as they may be designed to release if pressure within the burner box reaches an unsafe level. In one embodiment, liquid or solid fuels may be automatically metered into the burner box.
As shown in
The air distribution box 80 receives air provided by the air blower 76 and is connected to the two air distribution channels: one air supply line 89 to the left-sided distribution channel 81 and one 90 to the three-sided (left, front and right) air distribution channels 82. In addition, in one embodiment, the air distribution box provides a separate air supply 91 to the bottom of the burner box at a central location, and another air supply 92 to the burner box directly right beside the igniter box 84. The air distribution channels 81 and 82 comprise multiple holes 93 to the inside of burner box 73 and a cover 94 for each air distribution channel so that the channels can be opened for the channel cleaning.
The centre bottom air supply 91 provides additional oxygen to promote more complete combustion and ashing of the fuels in the ash chamber. The igniter box air supply 92 provides sufficient oxygen to support ignition when required. Each of the air supply lines 89, 90, 91, 92 may comprise adjustable valves which permit rebalancing the air supply throughout the burner box.
Air is distributed to the burner box through the multiple holes 93 and the volatilized gas oils 78 are withdrawn from the burner box to the gas oil channel 83 through the multiple holes 95. There is also a cover 24 similar to the cover 94 at the end of the gas oil exiting channels 83a and 83b for channel cleaning maintenance.
The specific configuration of air distribution holes and channels, as well as the gas oil outlet holes and channels illustrated in the Figures is not essential to the claimed invention. The introduction of air and withdrawal of gas oils may be designed to promote the processes which occur in the burner box. The air holes 93 are preferably positioned below the gas oil holes 95.
The igniter box 84 is disposed within the burner box 73 and comprises an igniter probe 96 and a gas (preferably propane or natural gas) nozzle 97. The igniter probes 96 are wired to a transformer in the electrical panel 98 and make sparks to light the gas (propane or natural gas). Alternatively, a plasma igniter or a conventional pilot light may be used to provide ignition in the burner box.
As shown in
The internal tube 99 comprises multiple fins 107 located at the exit side to enhance turbulent flow of the gas mixture, which assists in more thorough combustion in the combustion chamber 75. The combined flow into combustion chamber has the gas oils concentrated in a central portion, while the outer flow is predominantly air. The flow is turbulent, resulting in thorough mixing of the fuel gases and air, which provides thorough combustion.
Similar to the igniter box 84 attached to the burner box 73, the igniter box 108, as shown in
In one embodiment, as shown in
As may be seen in
The burner box 73 is primarily a fuel gasification unit. A wide variety of fuels may be volatilized into gas oils at a temperature not greater than 700° C. For example, it is known that an operating temperature of 200° C. is required to volatilize tires, and 400° C. is required to volatilize coals. The resulting gas oils are then burned thoroughly in the combustion chamber 75. This volatilizing process in the burner box is a combination of pyrolysis, gasification, cracking, vaporization and carbonization.
In the burner box, after all volatiles are volatilized, the residues need a higher temperature to burn into ash. However, it does not mean that the volatilizing room 117 has to be operated at an average temperature higher than 700° C. for ashing the residues, because ashing is in progress any time on surface of the fuels where localized temperatures could be more than 1000° C. The fuel is volatilized, and not burned, as a result of restricting oxygen supply to the burner box. Accordingly, the air flow rate in each air supply line 89, 90, 91 and 92 is controlled such that less than a stoichiometric combustion amount of air is supplied to the burner box 73.
The ash in the ash room 118 is removed or cleaned intermittently through a door 119 with hinges 120 and a door hook 121 hooked at the back side of the burner box 73 as shown in
As shown in
Liquid (used oil) or sludge (sludge with high oil content) fuel is supplied to each burner through the used oil inlet 85, and solid fuels (coal and/or scrap tires) are loaded intermittently into the volatilizing room 117 on the screen 116 after ash is removed. Alternatively, an automated fuel feeder may be provided. The gas (propane or natural gas) line from each co-combustion burner to a gas tank is connected with the gas (propane or natural gas) nozzles 97 and 110 on the two igniter boxes 84 and 108. Gas, liquid and sludge fuels are loaded continuously from the gas tank, used oil tank or sludge fuel tank, respectively.
In combination, the components the system described herein provides a process and system capable of remediating highly contaminated materials, making it suitable for a variety of applications. Applications include treatment of invert drill muds, residual tank bottoms, and contaminated soils. Combined with the operating flexibility of the unit, the process is capable of treating materials contaminated with both organic and inorganic constituents. The system may have application in the remediation of materials contaminated with contaminates such as non-halogenated and halogenated volatile and semi-volatile organics, fuels, and inorganics. These types of contaminates are associated with industrial wastes derived from agricultural, chemical processing, petroleum producing and refining, reuse processing, paint and ink manufacturing, plastics manufacturing and pharmaceutical manufacturing industries.
In one embodiment, the system may be configured to operate separately as low temperature thermal desorption, high temperature thermal desorption and pyrolysis systems or in series or as any combinations thereof.
In one embodiment, the system may be used in a method for producing oil from oil shale, oil sands, coal and any oil-bearing media without using water as extraction solvent. In these applications, solid feed stocks can be directly fed into the crasher, omitting the blender in the feeding line.
The process is easily adaptable to a wide range of operating parameters to control retention time, system operating pressure, operating temperature, and capacity to satisfy the end process treatment criteria for varying feedstock materials.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2660106 | Mar 2008 | CA | national |
This application claims the priority benefit of U.S. Provisional Patent Application 61/094,190 filed Sep. 4, 2008 entitled “System and Method for Treating Oil-Bearing Solids”, and Canadian Patent Application 2,660,106 filed Mar. 24, 2009 entitled “System and Method for Treating Oil-Bearing Media”, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61094190 | Sep 2008 | US |
