CA2091508C - Process to separate inorganic sludges containing non-volatile hydrocarbons - Google Patents
Process to separate inorganic sludges containing non-volatile hydrocarbonsInfo
- Publication number
- CA2091508C CA2091508C CA 2091508 CA2091508A CA2091508C CA 2091508 C CA2091508 C CA 2091508C CA 2091508 CA2091508 CA 2091508 CA 2091508 A CA2091508 A CA 2091508A CA 2091508 C CA2091508 C CA 2091508C
- Authority
- CA
- Canada
- Prior art keywords
- sludge
- solvent
- hydrocarbon
- water
- distillate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
- C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction
- C10G1/045—Separation of insoluble materials
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
- C10C3/00—Working-up pitch, asphalt, bitumen
- C10C3/007—Working-up pitch, asphalt, bitumen winning and separation of asphalt from mixtures with aggregates, fillers and other products, e.g. winning from natural asphalt and regeneration of waste asphalt
Abstract
A process that can break down mixtures of water, solids, non-volatile hydrocarbons and other accompanying substances into their primary constituents employs solvent extraction such that the water, which is to be recycled, does not contain any solids at all. The process makes it possible to process and break down oil-bearing sludge that accumulates during the hot water process of tar sands extraction, and which is stored in settling ponds and constitutes a permanent danger to the environment. The process lowers the proportion of solids in the recycled water to nearly zero, which permits sedimentation within a reasonably short period of time. The process is environmentally friendly and achieves high yields in bitumen separation with low energy and operating costs.
Description
1 - 2 ~ Q ~
Process to Separate Inorganic Sludqes Containing Non-Volatile Hydrocarbons The invention relates to a process to separate inorganic sludges containing non-volatile hydrocarbons.
Mixtures that are composed primarily of water, solids and non-volatile hydrocarbons are particularly suited to the application of the process of the invention, if they occur as a concentrated sludge, e.g. from a settling pond of bitumen production from tar sands and exhibit a high level of very fine grains which cannot be separated out economically by mechanical means. The hot water process of producing bitumen from tar sand leaves behind a waste product of very fine-grained, heated and bituminous sludge (up to 8% tar sand;
40 - 60~C); this sludge is pumped into a settling pond, which is used as a settling and concentration device. Water from the clear water zone of the pond is pumped back into the production process and reused. The very slowly settling oil-bearing sludge remains in the pond, and, because of its immense volume (several million cubic metres annually) involved in tar sands mining, constitutes a permanent danger to the environment. As well, because the capacity of the waste ponds is limited, an effort is being made to remove the water from the sludge until it becomes solid, and use the solid as fill for excavated pits.
DE-OS 29 21 654 describes a contact process for treating mixed waste materials that contain oil and/or oil byproducts, polluted water and solid sludge. In it, the oil components are extracted by means of a solvent from the waste material in a continuous multiple-chamber contact device in which the waste material and a solvent move in separate phases and are brought into contact with one another by means of containers revolving in the contact device. The solids are separated solely on the basis of the effect of gravitational forces, by which means it is not possible to achieve sufficient separation of the non-volatile hydrocarbons and the solid particles. The high proportion of very fine grains in the -- 2 ~ ~ ~ 5 ~ 8 ~
Process to Separate Inorganic Sludqes Containing Non-Volatile Hydrocarbons The invention relates to a process to separate inorganic sludges containing non-volatile hydrocarbons.
Mixtures that are composed primarily of water, solids and non-volatile hydrocarbons are particularly suited to the application of the process of the invention, if they occur as a concentrated sludge, e.g. from a settling pond of bitumen production from tar sands and exhibit a high level of very fine grains which cannot be separated out economically by mechanical means. The hot water process of producing bitumen from tar sand leaves behind a waste product of very fine-grained, heated and bituminous sludge (up to 8% tar sand;
40 - 60~C); this sludge is pumped into a settling pond, which is used as a settling and concentration device. Water from the clear water zone of the pond is pumped back into the production process and reused. The very slowly settling oil-bearing sludge remains in the pond, and, because of its immense volume (several million cubic metres annually) involved in tar sands mining, constitutes a permanent danger to the environment. As well, because the capacity of the waste ponds is limited, an effort is being made to remove the water from the sludge until it becomes solid, and use the solid as fill for excavated pits.
DE-OS 29 21 654 describes a contact process for treating mixed waste materials that contain oil and/or oil byproducts, polluted water and solid sludge. In it, the oil components are extracted by means of a solvent from the waste material in a continuous multiple-chamber contact device in which the waste material and a solvent move in separate phases and are brought into contact with one another by means of containers revolving in the contact device. The solids are separated solely on the basis of the effect of gravitational forces, by which means it is not possible to achieve sufficient separation of the non-volatile hydrocarbons and the solid particles. The high proportion of very fine grains in the -- 2 ~ ~ ~ 5 ~ 8 ~
separated water does not permit significant sedimentation within a reasonably short period of time.
The purpose of the present invention is to develop a process that can break down mixtures of water, solids, non-volatile hydrocarbons and other accompanying substances totheir primary constituents, as a result of which water can be produced to be recycled, that does not contain any solids at all.
Thus, according to one aspect of the invention there is provided a process of separating constituents of inorganic sludges of variable water content containing non-volatile hydrocarbons, comprising: (a) preheating the sludge and diluting the sludge with water to form a diluted sludge, and then contacting the diluted sludge in a reactor with a solvent that is insoluble with the diluted sludge to form a sludge/solvent interface while creating eddy currents in the diluted sludge to roll the diluted sludge towards the sludge/solvent interface, thus forming a solids-free hydrocarbon-containing solution and an extracted sludge containing residual solvent and hydrocarbon; (b) removing said solids-free hydrocarbon-containing solution from the reactor and subjecting the solution to spray film vaporization to form a solvent vapour and a fluid hydrocarbon-containing fraction;
(c) subjecting the hydrocarbon-containing fraction to sedimentation to form a hydrocarbon/solvent concentrate and a first hydrocarbon product, and subjecting the hydrocarbon/solvent concentrate to fluid bed vaporization to form a solvent vapour and a second hydrocarbon product which is combined with said first hydrocarbon product; (d) removing extracted sludge from the reactor and subjecting said sludge to preheating and then to degasification to expel residual solvent, leaving a degassed sludge; (e) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate; (f) skimming residual hydrocarbon from the distillate from the vaporization step to form a third hydrocarbon product and a skimmed solids-free water; (g) returning the skimmed solid-free water from the distillate to the process; (h) condensing solvent vapour from steps (b) and (c) to form a recovered liquid solvent, and returning said recovered liquid product to the process; and (i) discarding said semi-solid sludge.
According to another aspect of the invention, there is provided a process to separate constituents of inorganic sludges containing water, volatile hydrocarbons and non-volatile hydrocarbons, comprising: (a) preheating the sludge;
(b) degassing the preheated sludge to remove volatile hydrocarbons, leaving a degassed sludge; (c) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate; (d) removing residual hydrocarbon from the distillate from the vaporization step to form a hydrocarbon product and a solids-free water; (e) returning the solid-free water from the distillate to the process; and (f) discarding the semi-solid sludge.
A preferred form of the invention involves mixing preheated sludge, which has been diluted with water, with solvent in an extraction reactor in such a way that eddies result in the oil phase, thus rolling the oil-bearing sludge against a surface to the solvent. A completely solids-free solvent removal is carried out in a first stage by a horizontal tubular spray film vaporizer with vapour compression, and in a second stage by a fluidized bed evaporator which is preceded by a sedimentation device. The extracted sludge is fed to degasification, via a preheating phase, to expel the residual solvents, and the water is extracted from the degassed sludge by means of a sludge vaporizer using vapour compression. The residual oils of the distillate from the vaporizer are removed by means of a skimmer, and the solids-free water is returned to the process.
The semi-solid sludge can be dumped without harm to the environment.
This process makes it possible to process and break down into its principal constituents the oil-bearing sludge that accumulates during the hot water process and is stored in ~' ~_ _ 4 ~ 8 settling ponds to constitute a permanent danger to the environment. Moreover, the present process lowers the proportion of solids in the recycled water to nearly zero, which permits sedimentation within a reasonably short period of time. This environmentally friendly process achieves high yields in bitumen separation at low energy and operating costs.
Another feature of the process is that an organic CFC-free solvent may be used as the solvent. An example is light petroleum. Many other hydrocarbon-containing solvents are equally suitable for extraction. The application depends, in part, on the type of hydrocarbon to be dissolved. If the bitumen or other hard to refine hydrocarbons contain benzene ring or polar compounds, then similar solvents, such as toluene or benzene, are recommended. The suitability limits of the solvent are set by a solvent recovery with a sufficiently large difference in boiling points between the solvent and the substance dissolved, its availability on site, the production price, environmental compatibility, and compatibility with the subsequent stages of production. In addition to the environmental reasons, solvents containing CFC
must also be ruled out because of halogen traces in bitumen processing, which are harmful to the catalyst.
Another advantageous feature of the process is that the sludge, preheated and diluted with water, can be fed directly into the degasser, eliminating the solvent extraction phase, the degassed sludge being dewatered in the sludge vaporizer, using vapour compression. This version of the process is particularly advantageous if the bitumen in the dried oil-bearing sludge does not constitute any danger to the environment. This version of the process can save the entire step of solvent extraction.
The invention will be explained below in greater detail by means of examples.
Figure 1 schematically illustrates a revolving extraction container.
Figure 2 shows a process flow diagram of an embodiment of the invention with solvent extraction.
Figure 3 shows a process flow diagram of an embodiment without solvent extraction.
Deposited sludge from a settling pond is pumped to a heating station which is not shown. If necessary, the pumpability of the sludge is ensured by mixing it with water.
The heating station consists of a heat exchanger, which uses the heat of a stream of water flowing into a waste pond to heat the sludge for extraction. In the hot water process, the stream of water flowing into the waste pond is about four times as large as the quantity of sludge from which water is to be removed, so that enough heat is available. The sludge (about 30~ dried matter-DM) is warmed from about 0~C to 40~C
during this process. A second heating (superheating of the light fractions of the petroleum benzine) of up to 60~C can be achieved by steam. Because the necessary steam is not subject to heavy demands with respect to pressure and temperature, it is often possible to reuse steam that is present in the mine, but has not been reused (waste steam).
After being heated, the sludge G reaches an extraction reactor 1 (Figures 1 and 2). A solvent Lm floats on the oil-bearing sludge G in which it is not soluble. The substance exchange (extraction of bitumen from the oil-bearing sludge into the solvent) between the solvent Lm and the oil-bearing sludge G takes place through an interface surface P.
Therefore, the area of this surface must be large, which results in relatively low extraction reactors with large surface areas. The oil-bearing sludge G is mixed by a propeller agitator 1B in such a way that two eddy currents are created in the oil phase and roll the oil-bearing sludge G
towards the solvent at the dividing surface P. It is important that this mixing process should not send any solvent into the oil phase. In order to permit a thorough mixing of the individual phases (solvent and oil-bearing sludge) in the direction of the perimeter, a slow-speed anchor agitator 1A is fitted in the reactor. Solvent discharge LmA removed from the 6 ~
reactor is completely free of solids and, as shown in Figure 2, is fed into a two-stage vaporizer unit for bitumen separation/solvent recovery. Stage 1 of this unit consists of an energy-saving, horizontal tubular spray film vaporizer 2A
with vapour compression, and Stage 2 consists of a fluidized bed vaporizer 2B which is not sensitive to contamination, and creates a bitumen discharge B. In order to minimize energy consumption in Stage 2, it is preceded by a bitumen settling device 3 which reduces the quantity of bitumen concentrate in Stage 2, and adds to the bitumen discharge B.
The extracted oil-bearing sludge GE is carried from the extraction reactor 1 via a preheating step 4 (with hot dilute sludge from the hot water process) to a degasification step 5, in order to expel the residue of the extraction agent. Water is removed from the degassed sludge GG by vapour compression in a sludge vaporizer 6. The distillate D from this vaporizer contains residual oil R, which is removed by a skimmer 7. The water W is returned to the production process. The dried sludge S is semi-solid (DM content greater than 70~) and can be dumped. Solvent separation must preferably be set up so that the solvent recovery rates are in excess of 99~ in order to achieve an economical operation of the system. The solvent recovery or loss rate is here defined as being such that less than 1~ of the solvent stream used in the reaction extractor is removed via waste air, decanter sediment and water, or that over 99~ of the solvent used is regenerated. The solvent recovery apparatus can also take the form of a conventional multi-stage evaporator (not shown) whose stages vaporize solvents at various pressures. The condensation heat of the solvent vapour is used as vaporizing heat for each following evaporation stage, so that the heat employed is used in the form of stripping steam for each stage and thereby contributes to saving energy in the most energy-intensive step of the process. The solvent vapour from the final stage releases its condensation heat to warm the oil-bearing sludge stream from the extraction reactor, or is used to heat the sludge used in the system feed. As in all multistage concentrators, the ,, ~
-number of evaporation stages is arrived at through calculation of economic viability, in which capital costs are set off against the savings of energy over the write-off period.
For optimal use of energy and to ensure constantly operating temperature differences, the solvent stream from the extraction reactor is so fed into the conventional multistage vaporizer as to flow counter to the heat carrier (already evaporated solvent). In this process, the solvent evaporates out of the solvent stream and the remaining bitumen is concentrated on the surface of the liquid. This bitumen is skimmed off and is available for further processing in the bitumen processing process. The skimmer need not be integrated in the vaporizer. For reasons of cost, the skimmer can also be installed outside the vaporizer, which makes particular sense if low levels of bitumen do not obstruct solvent evaporation by solid formation of bitumen film.
Solvent recovery can also be carried out in multistage vaporizers, in which the heat carrier flows in parallel with the solvent to be concentrated. The skimmed water is absolutely free of solids and can be used to heat the sludge used or fed directly into the hot water process of bitumen extraction. All installations and equipment in the process are constructed in an enclosed form and have no contact with the surrounding air, in order to avoid solvent loss through evaporation and offensive odours. The solvent losses occur as a result of residual solubilities of the solvent, which is itself insoluble in the skimmed-off water, and by removal of solvent in the solids discharge in the dryer. The small quantities of solvent in the water are quickly broken down biologically. The solvent residues in the sand are broken down by soil bacteria as well, as they constitute nontoxic biologically degradable compounds.
According to another example (Figure 3), the process can be carried out without solvent extraction, especially if the presence of bitumen in the dried discarded sludge does not constitute an environmental hazard. As illustrated in Figure 3 this process relies primarily on the sludge vaporizer 6, to j~
- 8 - 2~
which the degassed oil-bearing sludge from the settling ponds is fed after being heated in a heat exchanger 8.
The volatile hydrocarbons LF are separated in a degasser 5. The water WA evaporated off in the sludge vaporizer 6 is fed via a heat exchanger 8 to a phase separator 9, where it is completely released from the residual oil R. The separated water W is completely free of solids.
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. ~, ~
The purpose of the present invention is to develop a process that can break down mixtures of water, solids, non-volatile hydrocarbons and other accompanying substances totheir primary constituents, as a result of which water can be produced to be recycled, that does not contain any solids at all.
Thus, according to one aspect of the invention there is provided a process of separating constituents of inorganic sludges of variable water content containing non-volatile hydrocarbons, comprising: (a) preheating the sludge and diluting the sludge with water to form a diluted sludge, and then contacting the diluted sludge in a reactor with a solvent that is insoluble with the diluted sludge to form a sludge/solvent interface while creating eddy currents in the diluted sludge to roll the diluted sludge towards the sludge/solvent interface, thus forming a solids-free hydrocarbon-containing solution and an extracted sludge containing residual solvent and hydrocarbon; (b) removing said solids-free hydrocarbon-containing solution from the reactor and subjecting the solution to spray film vaporization to form a solvent vapour and a fluid hydrocarbon-containing fraction;
(c) subjecting the hydrocarbon-containing fraction to sedimentation to form a hydrocarbon/solvent concentrate and a first hydrocarbon product, and subjecting the hydrocarbon/solvent concentrate to fluid bed vaporization to form a solvent vapour and a second hydrocarbon product which is combined with said first hydrocarbon product; (d) removing extracted sludge from the reactor and subjecting said sludge to preheating and then to degasification to expel residual solvent, leaving a degassed sludge; (e) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate; (f) skimming residual hydrocarbon from the distillate from the vaporization step to form a third hydrocarbon product and a skimmed solids-free water; (g) returning the skimmed solid-free water from the distillate to the process; (h) condensing solvent vapour from steps (b) and (c) to form a recovered liquid solvent, and returning said recovered liquid product to the process; and (i) discarding said semi-solid sludge.
According to another aspect of the invention, there is provided a process to separate constituents of inorganic sludges containing water, volatile hydrocarbons and non-volatile hydrocarbons, comprising: (a) preheating the sludge;
(b) degassing the preheated sludge to remove volatile hydrocarbons, leaving a degassed sludge; (c) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate; (d) removing residual hydrocarbon from the distillate from the vaporization step to form a hydrocarbon product and a solids-free water; (e) returning the solid-free water from the distillate to the process; and (f) discarding the semi-solid sludge.
A preferred form of the invention involves mixing preheated sludge, which has been diluted with water, with solvent in an extraction reactor in such a way that eddies result in the oil phase, thus rolling the oil-bearing sludge against a surface to the solvent. A completely solids-free solvent removal is carried out in a first stage by a horizontal tubular spray film vaporizer with vapour compression, and in a second stage by a fluidized bed evaporator which is preceded by a sedimentation device. The extracted sludge is fed to degasification, via a preheating phase, to expel the residual solvents, and the water is extracted from the degassed sludge by means of a sludge vaporizer using vapour compression. The residual oils of the distillate from the vaporizer are removed by means of a skimmer, and the solids-free water is returned to the process.
The semi-solid sludge can be dumped without harm to the environment.
This process makes it possible to process and break down into its principal constituents the oil-bearing sludge that accumulates during the hot water process and is stored in ~' ~_ _ 4 ~ 8 settling ponds to constitute a permanent danger to the environment. Moreover, the present process lowers the proportion of solids in the recycled water to nearly zero, which permits sedimentation within a reasonably short period of time. This environmentally friendly process achieves high yields in bitumen separation at low energy and operating costs.
Another feature of the process is that an organic CFC-free solvent may be used as the solvent. An example is light petroleum. Many other hydrocarbon-containing solvents are equally suitable for extraction. The application depends, in part, on the type of hydrocarbon to be dissolved. If the bitumen or other hard to refine hydrocarbons contain benzene ring or polar compounds, then similar solvents, such as toluene or benzene, are recommended. The suitability limits of the solvent are set by a solvent recovery with a sufficiently large difference in boiling points between the solvent and the substance dissolved, its availability on site, the production price, environmental compatibility, and compatibility with the subsequent stages of production. In addition to the environmental reasons, solvents containing CFC
must also be ruled out because of halogen traces in bitumen processing, which are harmful to the catalyst.
Another advantageous feature of the process is that the sludge, preheated and diluted with water, can be fed directly into the degasser, eliminating the solvent extraction phase, the degassed sludge being dewatered in the sludge vaporizer, using vapour compression. This version of the process is particularly advantageous if the bitumen in the dried oil-bearing sludge does not constitute any danger to the environment. This version of the process can save the entire step of solvent extraction.
The invention will be explained below in greater detail by means of examples.
Figure 1 schematically illustrates a revolving extraction container.
Figure 2 shows a process flow diagram of an embodiment of the invention with solvent extraction.
Figure 3 shows a process flow diagram of an embodiment without solvent extraction.
Deposited sludge from a settling pond is pumped to a heating station which is not shown. If necessary, the pumpability of the sludge is ensured by mixing it with water.
The heating station consists of a heat exchanger, which uses the heat of a stream of water flowing into a waste pond to heat the sludge for extraction. In the hot water process, the stream of water flowing into the waste pond is about four times as large as the quantity of sludge from which water is to be removed, so that enough heat is available. The sludge (about 30~ dried matter-DM) is warmed from about 0~C to 40~C
during this process. A second heating (superheating of the light fractions of the petroleum benzine) of up to 60~C can be achieved by steam. Because the necessary steam is not subject to heavy demands with respect to pressure and temperature, it is often possible to reuse steam that is present in the mine, but has not been reused (waste steam).
After being heated, the sludge G reaches an extraction reactor 1 (Figures 1 and 2). A solvent Lm floats on the oil-bearing sludge G in which it is not soluble. The substance exchange (extraction of bitumen from the oil-bearing sludge into the solvent) between the solvent Lm and the oil-bearing sludge G takes place through an interface surface P.
Therefore, the area of this surface must be large, which results in relatively low extraction reactors with large surface areas. The oil-bearing sludge G is mixed by a propeller agitator 1B in such a way that two eddy currents are created in the oil phase and roll the oil-bearing sludge G
towards the solvent at the dividing surface P. It is important that this mixing process should not send any solvent into the oil phase. In order to permit a thorough mixing of the individual phases (solvent and oil-bearing sludge) in the direction of the perimeter, a slow-speed anchor agitator 1A is fitted in the reactor. Solvent discharge LmA removed from the 6 ~
reactor is completely free of solids and, as shown in Figure 2, is fed into a two-stage vaporizer unit for bitumen separation/solvent recovery. Stage 1 of this unit consists of an energy-saving, horizontal tubular spray film vaporizer 2A
with vapour compression, and Stage 2 consists of a fluidized bed vaporizer 2B which is not sensitive to contamination, and creates a bitumen discharge B. In order to minimize energy consumption in Stage 2, it is preceded by a bitumen settling device 3 which reduces the quantity of bitumen concentrate in Stage 2, and adds to the bitumen discharge B.
The extracted oil-bearing sludge GE is carried from the extraction reactor 1 via a preheating step 4 (with hot dilute sludge from the hot water process) to a degasification step 5, in order to expel the residue of the extraction agent. Water is removed from the degassed sludge GG by vapour compression in a sludge vaporizer 6. The distillate D from this vaporizer contains residual oil R, which is removed by a skimmer 7. The water W is returned to the production process. The dried sludge S is semi-solid (DM content greater than 70~) and can be dumped. Solvent separation must preferably be set up so that the solvent recovery rates are in excess of 99~ in order to achieve an economical operation of the system. The solvent recovery or loss rate is here defined as being such that less than 1~ of the solvent stream used in the reaction extractor is removed via waste air, decanter sediment and water, or that over 99~ of the solvent used is regenerated. The solvent recovery apparatus can also take the form of a conventional multi-stage evaporator (not shown) whose stages vaporize solvents at various pressures. The condensation heat of the solvent vapour is used as vaporizing heat for each following evaporation stage, so that the heat employed is used in the form of stripping steam for each stage and thereby contributes to saving energy in the most energy-intensive step of the process. The solvent vapour from the final stage releases its condensation heat to warm the oil-bearing sludge stream from the extraction reactor, or is used to heat the sludge used in the system feed. As in all multistage concentrators, the ,, ~
-number of evaporation stages is arrived at through calculation of economic viability, in which capital costs are set off against the savings of energy over the write-off period.
For optimal use of energy and to ensure constantly operating temperature differences, the solvent stream from the extraction reactor is so fed into the conventional multistage vaporizer as to flow counter to the heat carrier (already evaporated solvent). In this process, the solvent evaporates out of the solvent stream and the remaining bitumen is concentrated on the surface of the liquid. This bitumen is skimmed off and is available for further processing in the bitumen processing process. The skimmer need not be integrated in the vaporizer. For reasons of cost, the skimmer can also be installed outside the vaporizer, which makes particular sense if low levels of bitumen do not obstruct solvent evaporation by solid formation of bitumen film.
Solvent recovery can also be carried out in multistage vaporizers, in which the heat carrier flows in parallel with the solvent to be concentrated. The skimmed water is absolutely free of solids and can be used to heat the sludge used or fed directly into the hot water process of bitumen extraction. All installations and equipment in the process are constructed in an enclosed form and have no contact with the surrounding air, in order to avoid solvent loss through evaporation and offensive odours. The solvent losses occur as a result of residual solubilities of the solvent, which is itself insoluble in the skimmed-off water, and by removal of solvent in the solids discharge in the dryer. The small quantities of solvent in the water are quickly broken down biologically. The solvent residues in the sand are broken down by soil bacteria as well, as they constitute nontoxic biologically degradable compounds.
According to another example (Figure 3), the process can be carried out without solvent extraction, especially if the presence of bitumen in the dried discarded sludge does not constitute an environmental hazard. As illustrated in Figure 3 this process relies primarily on the sludge vaporizer 6, to j~
- 8 - 2~
which the degassed oil-bearing sludge from the settling ponds is fed after being heated in a heat exchanger 8.
The volatile hydrocarbons LF are separated in a degasser 5. The water WA evaporated off in the sludge vaporizer 6 is fed via a heat exchanger 8 to a phase separator 9, where it is completely released from the residual oil R. The separated water W is completely free of solids.
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Claims (9)
1. A process of separating constituents of inorganic sludges of variable water content containing non-volatile hydrocarbons, comprising:
(a) preheating the sludge and diluting the sludge with water to form a diluted sludge, and then contacting the diluted sludge in a reactor with a solvent that is insoluble with the diluted sludge to form a sludge/solvent interface while creating eddy currents in the diluted sludge to roll the diluted sludge towards the sludge/solvent interface, thus forming a solids-free hydrocarbon-containing solution and an extracted sludge containing residual solvent and hydrocarbon;
(b) removing said solids-free hydrocarbon-containing solution from the reactor and subjecting the solution to spray film vaporization to form a solvent vapour and a fluid hydrocarbon-containing fraction;
(c) subjecting the hydrocarbon-containing fraction to sedimentation to form a hydrocarbon/solvent concentrate and a first hydrocarbon product, and subjecting the hydrocarbon/solvent concentrate to fluid bed vaporization to form a solvent vapour and a second hydrocarbon product which is combined with said first hydrocarbon product;
(d) removing extracted sludge from the reactor and subjecting said sludge to preheating and then to degasification to expel residual solvent, leaving a degassed sludge;
(e) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate;
(f) skimming residual hydrocarbon from the distillate from the vaporization step to form a third hydrocarbon product and a skimmed solids-free water;
(g) returning the skimmed solid-free water from the distillate to the process;
(h) condensing solvent vapour from steps (b) and (c) to form a recovered liquid solvent, and returning said recovered liquid product to the process; and (i) discarding said semi-solid sludge.
(a) preheating the sludge and diluting the sludge with water to form a diluted sludge, and then contacting the diluted sludge in a reactor with a solvent that is insoluble with the diluted sludge to form a sludge/solvent interface while creating eddy currents in the diluted sludge to roll the diluted sludge towards the sludge/solvent interface, thus forming a solids-free hydrocarbon-containing solution and an extracted sludge containing residual solvent and hydrocarbon;
(b) removing said solids-free hydrocarbon-containing solution from the reactor and subjecting the solution to spray film vaporization to form a solvent vapour and a fluid hydrocarbon-containing fraction;
(c) subjecting the hydrocarbon-containing fraction to sedimentation to form a hydrocarbon/solvent concentrate and a first hydrocarbon product, and subjecting the hydrocarbon/solvent concentrate to fluid bed vaporization to form a solvent vapour and a second hydrocarbon product which is combined with said first hydrocarbon product;
(d) removing extracted sludge from the reactor and subjecting said sludge to preheating and then to degasification to expel residual solvent, leaving a degassed sludge;
(e) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate;
(f) skimming residual hydrocarbon from the distillate from the vaporization step to form a third hydrocarbon product and a skimmed solids-free water;
(g) returning the skimmed solid-free water from the distillate to the process;
(h) condensing solvent vapour from steps (b) and (c) to form a recovered liquid solvent, and returning said recovered liquid product to the process; and (i) discarding said semi-solid sludge.
2. The process of claim 1, wherein said non-volatile hydrocarbon is bitumen.
3. The process of claim 1, wherein said solvent is an organic CFC-free solvent.
4. The process of claim 1, wherein said solvent is a hydrocarbon.
5. The process of claim 4, wherein solvent is selected from light petroleum, toluene and benzene.
6. The process of claim 1, wherein the distillate from step (e) is used to preheat said sludge in step (d).
7. A process to separate constituents of inorganic sludges containing water, volatile hydrocarbons and non-volatile hydrocarbons, comprising:
(a) preheating the sludge;
(b) degassing the preheated sludge to remove volatile hydrocarbons, leaving a degassed sludge;
(c) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate;
(d) removing residual hydrocarbon from the distillate from the vaporization step to form a hydrocarbon product and a solids-free water;
(e) returning the solid-free water from the distillate to the process; and (f) discarding the semi-solid sludge.
(a) preheating the sludge;
(b) degassing the preheated sludge to remove volatile hydrocarbons, leaving a degassed sludge;
(c) removing water from the degassed sludge by vaporization with vapour compression to form a dewatered semi-solid sludge and a distillate;
(d) removing residual hydrocarbon from the distillate from the vaporization step to form a hydrocarbon product and a solids-free water;
(e) returning the solid-free water from the distillate to the process; and (f) discarding the semi-solid sludge.
8. The process of claim 7, wherein said residual hydrocarbon is removed from the distillate in step (d) by skimming.
9. The process of claim 7, wherein the distillate from step (c) is used to preheat the sludge in step (a).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4208181 | 1992-03-12 | ||
| DEP4208181.5 | 1992-03-12 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2091508A1 CA2091508A1 (en) | 1993-09-13 |
| CA2091508C true CA2091508C (en) | 1999-05-04 |
Family
ID=6454059
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2091508 Expired - Fee Related CA2091508C (en) | 1992-03-12 | 1993-03-11 | Process to separate inorganic sludges containing non-volatile hydrocarbons |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2091508C (en) |
| DE (1) | DE4233584C2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5766412A (en) * | 1997-01-13 | 1998-06-16 | Recovery Technologies Corporation | System and method of waster water reduction and product recovery |
| WO2002102938A1 (en) * | 2001-06-18 | 2002-12-27 | Sasol Technology (Pty) Ltd | Method of separating particles from a hydrocarbon composition |
| WO2007056670A2 (en) | 2005-11-02 | 2007-05-18 | Jay Duke | Apparatus, system, and method for separating minerals from mineral feedstock |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4067796A (en) * | 1975-05-27 | 1978-01-10 | Standard Oil Company | Tar sands recovery process |
-
1992
- 1992-10-06 DE DE4233584A patent/DE4233584C2/en not_active Expired - Fee Related
-
1993
- 1993-03-11 CA CA 2091508 patent/CA2091508C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE4233584C2 (en) | 1995-05-11 |
| CA2091508A1 (en) | 1993-09-13 |
| DE4233584A1 (en) | 1993-09-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |