CA1172193A - Process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine-ground lignite and oil - Google Patents
Process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine-ground lignite and oilInfo
- Publication number
- CA1172193A CA1172193A CA000403490A CA403490A CA1172193A CA 1172193 A CA1172193 A CA 1172193A CA 000403490 A CA000403490 A CA 000403490A CA 403490 A CA403490 A CA 403490A CA 1172193 A CA1172193 A CA 1172193A
- Authority
- CA
- Canada
- Prior art keywords
- lignite
- oil
- suspension
- hydrocarbon
- water
- 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
Links
- 239000003077 lignite Substances 0.000 title claims abstract description 65
- 239000000725 suspension Substances 0.000 title claims abstract description 51
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 5
- 239000003921 oil Substances 0.000 claims abstract description 48
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 25
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 25
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 25
- 238000009835 boiling Methods 0.000 claims abstract description 17
- 239000007788 liquid Substances 0.000 claims abstract description 11
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 10
- 239000002002 slurry Substances 0.000 claims abstract description 9
- 238000004821 distillation Methods 0.000 claims abstract description 8
- 238000001704 evaporation Methods 0.000 claims abstract description 8
- 230000008020 evaporation Effects 0.000 claims abstract description 8
- 239000012053 oil suspension Substances 0.000 claims abstract description 8
- 238000000926 separation method Methods 0.000 claims abstract description 6
- 239000003502 gasoline Substances 0.000 claims description 26
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 239000011261 inert gas Substances 0.000 claims description 9
- 238000007664 blowing Methods 0.000 claims description 8
- 239000003245 coal Substances 0.000 claims description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 4
- 238000005187 foaming Methods 0.000 claims description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 2
- 239000001569 carbon dioxide Substances 0.000 claims description 2
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims description 2
- 230000002459 sustained effect Effects 0.000 claims description 2
- 238000003763 carbonization Methods 0.000 claims 2
- 238000010438 heat treatment Methods 0.000 abstract description 6
- 238000002156 mixing Methods 0.000 abstract description 6
- 239000010802 sludge Substances 0.000 abstract description 5
- 230000018044 dehydration Effects 0.000 abstract description 4
- 238000006297 dehydration reaction Methods 0.000 abstract description 4
- 238000000227 grinding Methods 0.000 abstract description 2
- 239000012071 phase Substances 0.000 description 12
- 239000000203 mixture Substances 0.000 description 11
- 239000008346 aqueous phase Substances 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000005191 phase separation Methods 0.000 description 4
- 238000010533 azeotropic distillation Methods 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L1/00—Liquid carbonaceous fuels
- C10L1/32—Liquid carbonaceous fuels consisting of coal-oil suspensions or aqueous emulsions or oil emulsions
- C10L1/322—Coal-oil suspensions
Abstract
ABSTRACT
A process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine ground lignite and oil is provided which process comprises mixing ground hydrous lignite with oil of a higher boiling point and with a lower boiling hydrocarbon or hydrocarbon fraction to form a pumpable suspension, grinding the lignite in the suspension in a grain size of less than 2 mm., subjecting the suspension to a pressure of 30 to 80 bar and heating it to a temperature of 190 to 240 °C, maintaining the suspension under these conditions for at least 5 minutes, separating the suspension into a partially dehydrated lignite and oil slurry and a water, hydrocarbon and oil liquid, mixing the lignite and oil slurry with an oily phase obtained from separation of the water, hydrocarbon and oil and depressurizing the lignite and oil slurry to 1 to 18 bar at a temperature of 190 to 240 °C so as to obtain a dehydrated lignite and oil suspension and a water and hydrocarbon fraction.
The process of the present invention overcomes the expense as regards energy and equipment and the influence on the thermal efficiency of the hydrogenation process associated with known methods of dehydration by evaporation, and obviates the need for large heat exchangers as is required with the removal of water by distillation. Moreover, the hydrous lignite and oil sludge exhibits good flowability.
A process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine ground lignite and oil is provided which process comprises mixing ground hydrous lignite with oil of a higher boiling point and with a lower boiling hydrocarbon or hydrocarbon fraction to form a pumpable suspension, grinding the lignite in the suspension in a grain size of less than 2 mm., subjecting the suspension to a pressure of 30 to 80 bar and heating it to a temperature of 190 to 240 °C, maintaining the suspension under these conditions for at least 5 minutes, separating the suspension into a partially dehydrated lignite and oil slurry and a water, hydrocarbon and oil liquid, mixing the lignite and oil slurry with an oily phase obtained from separation of the water, hydrocarbon and oil and depressurizing the lignite and oil slurry to 1 to 18 bar at a temperature of 190 to 240 °C so as to obtain a dehydrated lignite and oil suspension and a water and hydrocarbon fraction.
The process of the present invention overcomes the expense as regards energy and equipment and the influence on the thermal efficiency of the hydrogenation process associated with known methods of dehydration by evaporation, and obviates the need for large heat exchangers as is required with the removal of water by distillation. Moreover, the hydrous lignite and oil sludge exhibits good flowability.
Description
~7Z1~3 This invention relates to a process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine ground lignite and oil. Suspensions of this kind are used for subsequent hydrogenation at temperatures of 300 to 500 QC and pressures of 100 to 700 bar.
~ Iydrogenation of lignite is a known process which was developed and perfected for industrial application by Bergius and Pier.
The lignite is prepared for hydrogenation by grinding and drying to a water content of preferably less than 5% and by mixing it with oil, thus obtaining a suspension. A higher water content would have an unfavourable effect on hydrogenation and on the pumpability of the lignite and oil suspension.
The relatively high pit humidity of the lignite, i.e. 50 to 60 %
water, referring to coal, requires a considerable expenditure for dehydration.
In the literature hitherto published, two methods of dehydration have been des-cribed. One method consists of drying the lignite with low pressure steam or hot flue gases. Another method, as referred to in the Canadian patent 978,877, comprises the mixing of the lignite with oil with subsequent removal of the water by distillation. Dehydration by evaporation is very expensive as regards energy and equipment and also influences the thermal efficiency of the hydro-genation process. Removal of the water by distillation, which requires very large heat exchange surfaces, is hardly feasible from an economical and in-dustial standpoint.
Another method described in DP~05~26 53 033 and 28 31 024, consists of mixing the pit wet lignite with oil and dehydrating the mixture at high temperatures and high pressures. The disadvantage of these methods resides in the poor flowability of the hydrous lignite and oil sludge. The sludge transport through pipes and heat exchangers presents considerable difficulties.
Another disadvantage is the relatively high expenditure for the equipment which ~7~ 3 is necessary for heating the suspension to temperatures above 250 C and for its subsequent cooling. A further disadvantage is the three phase separation of oil, water and oil soaked lignite which cannot be achieved by simple sedimentation of the phases.
The present invention seeks to eliminate the disadvantages of the known processes.
Thus, this invention provides a process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine ground lignite and oil wherein a) ground hydrous lignite is mixed with oil of a higher boiling point and with lower boiling hydrocarbon or hydrocarbon fraction to form a pump-; able suspension, b) the lignite in the suspension is ground to a grain size of less than 2 mm, c) the suspension is subjected to a pressure of 30 to 80 bar and heated to a temperature of 190 to 240 QC, dl the suspension is maintained under the conditions at step c) for at least 5 minutes, e~ the suspension is separated after step d) into a partially dehydrated lignite and oil slurry and a water, hydrocarbon and oil liquid, f) the lignite and oil slurry is mixed with an oily phase obtained in a water, hydrocarbon and oil separation step, and g~ the lignite and oil slurry is depressurized to 1 to 18 bar at a temperature of 190 to 240 QC SO as to obtain a dehydrated lignite and oil ~uspension and a water and hydrocarbon fraction.
In a preferred embodiment, the lower boiling hydrocarbon or hydro-carbon fraction is gasoline or a gasoline fraction.
~ Iydrogenation of lignite is a known process which was developed and perfected for industrial application by Bergius and Pier.
The lignite is prepared for hydrogenation by grinding and drying to a water content of preferably less than 5% and by mixing it with oil, thus obtaining a suspension. A higher water content would have an unfavourable effect on hydrogenation and on the pumpability of the lignite and oil suspension.
The relatively high pit humidity of the lignite, i.e. 50 to 60 %
water, referring to coal, requires a considerable expenditure for dehydration.
In the literature hitherto published, two methods of dehydration have been des-cribed. One method consists of drying the lignite with low pressure steam or hot flue gases. Another method, as referred to in the Canadian patent 978,877, comprises the mixing of the lignite with oil with subsequent removal of the water by distillation. Dehydration by evaporation is very expensive as regards energy and equipment and also influences the thermal efficiency of the hydro-genation process. Removal of the water by distillation, which requires very large heat exchange surfaces, is hardly feasible from an economical and in-dustial standpoint.
Another method described in DP~05~26 53 033 and 28 31 024, consists of mixing the pit wet lignite with oil and dehydrating the mixture at high temperatures and high pressures. The disadvantage of these methods resides in the poor flowability of the hydrous lignite and oil sludge. The sludge transport through pipes and heat exchangers presents considerable difficulties.
Another disadvantage is the relatively high expenditure for the equipment which ~7~ 3 is necessary for heating the suspension to temperatures above 250 C and for its subsequent cooling. A further disadvantage is the three phase separation of oil, water and oil soaked lignite which cannot be achieved by simple sedimentation of the phases.
The present invention seeks to eliminate the disadvantages of the known processes.
Thus, this invention provides a process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine ground lignite and oil wherein a) ground hydrous lignite is mixed with oil of a higher boiling point and with lower boiling hydrocarbon or hydrocarbon fraction to form a pump-; able suspension, b) the lignite in the suspension is ground to a grain size of less than 2 mm, c) the suspension is subjected to a pressure of 30 to 80 bar and heated to a temperature of 190 to 240 QC, dl the suspension is maintained under the conditions at step c) for at least 5 minutes, e~ the suspension is separated after step d) into a partially dehydrated lignite and oil slurry and a water, hydrocarbon and oil liquid, f) the lignite and oil slurry is mixed with an oily phase obtained in a water, hydrocarbon and oil separation step, and g~ the lignite and oil slurry is depressurized to 1 to 18 bar at a temperature of 190 to 240 QC SO as to obtain a dehydrated lignite and oil ~uspension and a water and hydrocarbon fraction.
In a preferred embodiment, the lower boiling hydrocarbon or hydro-carbon fraction is gasoline or a gasoline fraction.
- 2 -~72~3 By combining the features of the present invention, the disadvan-tages encountered in preparing the lignite or the subsequent hydrogenation process are reduced or eliminated and the necessary expenditure for energy and equipment is considerably reduced. Furthermore, the lignite can be dehydrated down to 0.5 % by weight.
By adding the gasoline fraction, the viscosity of the suspension is reduced by about a power of ten so that it may easily be delivered by centri-fugal pumps. The suspension is ed to a mill battery wher0 the lignite is ground to a grain size of less than 2 mm. The suspension is then pressurized by a centrifugal pump to 30 to 80 bar and subsequently heated to 190 to 240 C.
At these temperatures, the colloidal structure of the lignite is irreversibly destroyed. At the same time, the oxygenic oil causes the water to be displaced from the coal pores. Penetration of the oil into the coal pores is still promoted by the reduction of the viscosity due to the addition of the gasoline fraction so that temperaturesbetween 190 and 2~0 C are sufficient or this heat and pressure treatment.
Phase separation of the mixture consisting of the oil bearing layer, the water, and the oil soaked lignite is performed in two s~ages. In the first stage, separation of the liquid phase from the sollds takes place in a hydro-cyclone or decanting centrifuge. In the next stage, the oil bearing layer consisting of oil and of the gasoline raction is separated from the water.
After remixing the oil bearing layer with the lignite, the suspension is flash-ed in a stripper and the residual water is partly removed by azeotropic distil-lation together with the gasoline fraction. Evaporation is additionally promoted by feeding in inert gas. The condensed gasoline f~action is reused after phase separation.
Two embodiments of the process o the present invention are given, ~1~72~93 by way of example, in the following description.
In drawings which illustrate embodiments of the invention:
Figure 1 is a schema~ic representation of a first embodiment.
Figure 2 is a schematic representation of a second embodiment.
In the case of the embodiment of Figure 1, pit wet ground lignite is fed through line 1, oil through line 2, and a low boiling gasoline fraction through line 3 to mill battery 4 in which the lignite is ground to a grain size of less than 2 mm and mixed with the oil and the gasoline fraction. Pumpability of the suspension is achieved by adding the gasoline fraction. The pumpable : 10 suspension is fed through line 5 to a pump 6 by which the pressure of the suspension is increased to 30 to 80 bar. In heat exchanger 7 the suspension is heated to temperatures between 190 and 240 C. The heated suspension is sent through line 8 to a vessel 9 in which it remains for at least 5 minutes ~; at a temperature between 190 and 240 ~C.
At such temperatures, the colloidal structu~e of the lignite is irreversibly destroyed. At the same time, the water is displaced from the coal pores by the oll and the low boiling gasollne fracti~n.
;~ The suspension, in which more than 60 % of the pit moisture of the lignite has been displaced into the liquid phase, is conveyed tangentially through line 10 into hydrocyclone ll. The oil soaked partially dehydrated lignite, the density ~f which is higher than that o$ the li~uid phase, is separated at the cone wall and ls dlscharged by~ a pressure differentlal of up to 4 bar throug~ an open nozzle and into line l2. The coal sludge is then expanded in pressure letdGwn valve lg to a pressure that is by 2 to 3 bar lower than the discharge pressure. The inner eddy discharging towards the overflow nozzle cons-ists o~ a mixture of water, oil and gasoline.
~he liquid stream is sent through l me 13 to heat exchanger 14 for ' ~
~17Z~3 cooling to below 160 C. The cooled stream flows through line 15 to separator 16 in which the heavy aqueous phase is separated from the light oily phase.
The aqueous phase is drawn off through line 17. The oily phase consisting of an oil and gasoline mixture is added through line 18 to the partially dehydrated oil soaked lignite. After mixing, the oil bearing suspension passes through line 20 and! if necessary, is heated in heat exchanger 21 to a temperature between 190 and 240 C.
The suspension then passes through line 22 and is depressurized by pressure letdown valve 23 to 1 to 3 bar and then fed to stripper 24. De-pressurization causes the residual water of the suspension to evaporate. It is partially removed by azeotropic distillation together with the gasoline fraction. Evaporation is promoted by blowing in inert gas, such as nitrogen or carbon dioxide, through line 2~. The minimum retention time of the liquid in stripper 24 is 3 minutes. Foaming during evaporation is reduced by blowing the inert gas into stripper 24 laterally.
The overhead product o stripper 24 lS sent through line 23 to condenser 30. The three phases, i.e. the inert gas, the condensed gasoline fraction with a low oil content and the condensed heavy a~ueous layer pass through line 31 and are separated in stripper 32. The inert gas is removed through line 34 and the aqueous layer through line 33. The oily layer is returned via line 35, pump 36 and line 3 to mill battery 4.
The bottom product of stripper 24 consisting o~ a lignite and oil suspension with a water content o~ about 0.5 % is drawn of by pump 25 and through line 26. ~art stream 27 is recycled to avoid sedimentation of solids in the stripper. Having been pressurized and heated, the dehydrated lignite and oil suspension is used as feedstock for the hydrogenation process. The catalyst required for hydrogenation may already be added to the suspension in _ 5 ~L7~
mill battery 4 unless it is water soluble. ln the latter case it must beadmitted after the first phase separation step, in which water is separated from the lignite.
In another embodiment of the process o the invention as illus-trated in Figure 2, the suspension heated to 190 to 240 C is sent from vessel 9 through line 10 to heat exchanger 11, cooled down to a temperature corres-ponding to a maximum vapour pressure of the suspension of 10 bar and routed through line 12 into decanting centrifuge 13. The`decanted liquid is fed thro-ugh line 14 to oil and water separator 15 in which a light oily phase consisting of an oil and gasoline mixture is separated from a heavy aqueous phase. The aqueous phase is withdrawn via line 16. The oily phase is sent through line 17 to mixer 19 where it is mixed with the centrlfuged sludge passed into the mixer through line 18 to form a suspension consisting of lignite, oil and gasoline.
The suspension is sent by pump 20 through line 21 to heat exchanger 22 where it is heated to 190 to 240 ~C. Subsequently, the suspension is further processed by flashing in pressure letdown valve 23 and by~inert gas sustained azeotropic dIstillation, as in the first preferred embodiment illustrated in Figure 1.
The two process alternatives described offer the possibility of reducing the water content of the lignite and oil suspension to 0.5 %.
Example 1 In an experimental installation according to Pigure 2, 500 g of pit wet raw lignite with a water content of 54.4 % by weight, an ash content of 2.8 % by weight, and a grain siæe of less than 1 mm were mixed with 275 g of oil and 62.5 g o~ a gasoline fraction to form a suspension. The boiling range of the oil was 250 to 450 C and the density 0.973 g/cm3 at 20 ~C. The - 6 ~
~7Z~3 boiling range of the gasoline fraction was 110 to 140 C and the density 0.730 g/cm3 at 20 C.
The suspension was fed to an autoclave. The mixture was heated to 240 C, which temperature was maintained for 5 minutes. The heating caused the vapour pressure to rise to 42.5 bar. Then the mixture was cooled to 40 C and, after pressure compensation, centrifuged. Thus 385.5 g of clear liquid were obtained. This liquid was separated in a decanter into a light oily phase and a heavy aqueous phase. The aqueous phase contained 199.5 g of water, i.e.
73.4 % by weight of the water had been removed from the pit wet lignite without prior evaporation.
The light oily phase was mixed in a distillation flask with the centrifuge residue to form a suspension of oil, gaso]ine and partially de-hydrated lignite. On heating the suspension, an azeotropic mixture of water and gasoline and subsequently of water and oil with a low oil portion distilled at a top temperature of 92 to 96 C. ~istillation was promoted by blowing in nitrogen. Temporary foaming in the flask was reduced by blowing the nitrogen in laterally~.
The distillatlon process was stopped when a bottom temperature of 210 qC was reached. After condensation, the overhead product was separated in-to a reusable gasoline fraction of low oil content and a heavy aqueous layer.
The quantit~ o water separated amounted to 70.6 g. The water content of the lignite and oil suspension was 0.5 % by weight.
Example 2 ~or this test, the same raw materials were used as in example 1.
500 g of pit wet raw lignite with a water content of 54.4 % by weight, an ash content of 2.8 % by weight, and a grain size of less than 2 mm were mixed with 275 g of oil and 62.5 g of a gasoline fraction.
1~7Z~3 The suspension was fed to an autoclave. The mixture was heated to 200 C, which temperature was maintained for S minutes. The heating caused the vapour pressure to rise to 21 bar. The mixture was then cooled to 40 C
and subsequently centrifuged. The clear liquid obtained amounted to 361 g.
The clear liquid was separated in a decanter into a light oily phase and a heavy aqueous phase. The aqueous phase contained 182 g of water, i.e. 67 % by weight of the water had been removed from the pit wet lignite without prior evaporation.
The light oily phase was mixed in a distillation flask with the centrifuge residue to form a suspension of oil, gasoline and partially de-hydrated lignite. ~n heating the suspension, an a~eotropic mixture of water and gasoline and subs0quently of water and oil with a low oil portion distilled at a top temperature of 92 to 96 C, Distillation was promoted by blowing in nitrogen. Temporary foaming in the flask was reduced by blowing the nitrogen n laterally.
The distillation process was stopped when a bottom temperature of 210 C was reached. ~fter condensation, the overhead product was separated in-to a reusable gasoline fraction of low oil content and a heavy aqueous layer.
The quantity of water separated amounted to 87 g. The water content of the lignite and oil suspension was 0.8 % by weight.
By adding the gasoline fraction, the viscosity of the suspension is reduced by about a power of ten so that it may easily be delivered by centri-fugal pumps. The suspension is ed to a mill battery wher0 the lignite is ground to a grain size of less than 2 mm. The suspension is then pressurized by a centrifugal pump to 30 to 80 bar and subsequently heated to 190 to 240 C.
At these temperatures, the colloidal structure of the lignite is irreversibly destroyed. At the same time, the oxygenic oil causes the water to be displaced from the coal pores. Penetration of the oil into the coal pores is still promoted by the reduction of the viscosity due to the addition of the gasoline fraction so that temperaturesbetween 190 and 2~0 C are sufficient or this heat and pressure treatment.
Phase separation of the mixture consisting of the oil bearing layer, the water, and the oil soaked lignite is performed in two s~ages. In the first stage, separation of the liquid phase from the sollds takes place in a hydro-cyclone or decanting centrifuge. In the next stage, the oil bearing layer consisting of oil and of the gasoline raction is separated from the water.
After remixing the oil bearing layer with the lignite, the suspension is flash-ed in a stripper and the residual water is partly removed by azeotropic distil-lation together with the gasoline fraction. Evaporation is additionally promoted by feeding in inert gas. The condensed gasoline f~action is reused after phase separation.
Two embodiments of the process o the present invention are given, ~1~72~93 by way of example, in the following description.
In drawings which illustrate embodiments of the invention:
Figure 1 is a schema~ic representation of a first embodiment.
Figure 2 is a schematic representation of a second embodiment.
In the case of the embodiment of Figure 1, pit wet ground lignite is fed through line 1, oil through line 2, and a low boiling gasoline fraction through line 3 to mill battery 4 in which the lignite is ground to a grain size of less than 2 mm and mixed with the oil and the gasoline fraction. Pumpability of the suspension is achieved by adding the gasoline fraction. The pumpable : 10 suspension is fed through line 5 to a pump 6 by which the pressure of the suspension is increased to 30 to 80 bar. In heat exchanger 7 the suspension is heated to temperatures between 190 and 240 C. The heated suspension is sent through line 8 to a vessel 9 in which it remains for at least 5 minutes ~; at a temperature between 190 and 240 ~C.
At such temperatures, the colloidal structu~e of the lignite is irreversibly destroyed. At the same time, the water is displaced from the coal pores by the oll and the low boiling gasollne fracti~n.
;~ The suspension, in which more than 60 % of the pit moisture of the lignite has been displaced into the liquid phase, is conveyed tangentially through line 10 into hydrocyclone ll. The oil soaked partially dehydrated lignite, the density ~f which is higher than that o$ the li~uid phase, is separated at the cone wall and ls dlscharged by~ a pressure differentlal of up to 4 bar throug~ an open nozzle and into line l2. The coal sludge is then expanded in pressure letdGwn valve lg to a pressure that is by 2 to 3 bar lower than the discharge pressure. The inner eddy discharging towards the overflow nozzle cons-ists o~ a mixture of water, oil and gasoline.
~he liquid stream is sent through l me 13 to heat exchanger 14 for ' ~
~17Z~3 cooling to below 160 C. The cooled stream flows through line 15 to separator 16 in which the heavy aqueous phase is separated from the light oily phase.
The aqueous phase is drawn off through line 17. The oily phase consisting of an oil and gasoline mixture is added through line 18 to the partially dehydrated oil soaked lignite. After mixing, the oil bearing suspension passes through line 20 and! if necessary, is heated in heat exchanger 21 to a temperature between 190 and 240 C.
The suspension then passes through line 22 and is depressurized by pressure letdown valve 23 to 1 to 3 bar and then fed to stripper 24. De-pressurization causes the residual water of the suspension to evaporate. It is partially removed by azeotropic distillation together with the gasoline fraction. Evaporation is promoted by blowing in inert gas, such as nitrogen or carbon dioxide, through line 2~. The minimum retention time of the liquid in stripper 24 is 3 minutes. Foaming during evaporation is reduced by blowing the inert gas into stripper 24 laterally.
The overhead product o stripper 24 lS sent through line 23 to condenser 30. The three phases, i.e. the inert gas, the condensed gasoline fraction with a low oil content and the condensed heavy a~ueous layer pass through line 31 and are separated in stripper 32. The inert gas is removed through line 34 and the aqueous layer through line 33. The oily layer is returned via line 35, pump 36 and line 3 to mill battery 4.
The bottom product of stripper 24 consisting o~ a lignite and oil suspension with a water content o~ about 0.5 % is drawn of by pump 25 and through line 26. ~art stream 27 is recycled to avoid sedimentation of solids in the stripper. Having been pressurized and heated, the dehydrated lignite and oil suspension is used as feedstock for the hydrogenation process. The catalyst required for hydrogenation may already be added to the suspension in _ 5 ~L7~
mill battery 4 unless it is water soluble. ln the latter case it must beadmitted after the first phase separation step, in which water is separated from the lignite.
In another embodiment of the process o the invention as illus-trated in Figure 2, the suspension heated to 190 to 240 C is sent from vessel 9 through line 10 to heat exchanger 11, cooled down to a temperature corres-ponding to a maximum vapour pressure of the suspension of 10 bar and routed through line 12 into decanting centrifuge 13. The`decanted liquid is fed thro-ugh line 14 to oil and water separator 15 in which a light oily phase consisting of an oil and gasoline mixture is separated from a heavy aqueous phase. The aqueous phase is withdrawn via line 16. The oily phase is sent through line 17 to mixer 19 where it is mixed with the centrlfuged sludge passed into the mixer through line 18 to form a suspension consisting of lignite, oil and gasoline.
The suspension is sent by pump 20 through line 21 to heat exchanger 22 where it is heated to 190 to 240 ~C. Subsequently, the suspension is further processed by flashing in pressure letdown valve 23 and by~inert gas sustained azeotropic dIstillation, as in the first preferred embodiment illustrated in Figure 1.
The two process alternatives described offer the possibility of reducing the water content of the lignite and oil suspension to 0.5 %.
Example 1 In an experimental installation according to Pigure 2, 500 g of pit wet raw lignite with a water content of 54.4 % by weight, an ash content of 2.8 % by weight, and a grain siæe of less than 1 mm were mixed with 275 g of oil and 62.5 g o~ a gasoline fraction to form a suspension. The boiling range of the oil was 250 to 450 C and the density 0.973 g/cm3 at 20 ~C. The - 6 ~
~7Z~3 boiling range of the gasoline fraction was 110 to 140 C and the density 0.730 g/cm3 at 20 C.
The suspension was fed to an autoclave. The mixture was heated to 240 C, which temperature was maintained for 5 minutes. The heating caused the vapour pressure to rise to 42.5 bar. Then the mixture was cooled to 40 C and, after pressure compensation, centrifuged. Thus 385.5 g of clear liquid were obtained. This liquid was separated in a decanter into a light oily phase and a heavy aqueous phase. The aqueous phase contained 199.5 g of water, i.e.
73.4 % by weight of the water had been removed from the pit wet lignite without prior evaporation.
The light oily phase was mixed in a distillation flask with the centrifuge residue to form a suspension of oil, gaso]ine and partially de-hydrated lignite. On heating the suspension, an azeotropic mixture of water and gasoline and subsequently of water and oil with a low oil portion distilled at a top temperature of 92 to 96 C. ~istillation was promoted by blowing in nitrogen. Temporary foaming in the flask was reduced by blowing the nitrogen in laterally~.
The distillatlon process was stopped when a bottom temperature of 210 qC was reached. After condensation, the overhead product was separated in-to a reusable gasoline fraction of low oil content and a heavy aqueous layer.
The quantit~ o water separated amounted to 70.6 g. The water content of the lignite and oil suspension was 0.5 % by weight.
Example 2 ~or this test, the same raw materials were used as in example 1.
500 g of pit wet raw lignite with a water content of 54.4 % by weight, an ash content of 2.8 % by weight, and a grain size of less than 2 mm were mixed with 275 g of oil and 62.5 g of a gasoline fraction.
1~7Z~3 The suspension was fed to an autoclave. The mixture was heated to 200 C, which temperature was maintained for S minutes. The heating caused the vapour pressure to rise to 21 bar. The mixture was then cooled to 40 C
and subsequently centrifuged. The clear liquid obtained amounted to 361 g.
The clear liquid was separated in a decanter into a light oily phase and a heavy aqueous phase. The aqueous phase contained 182 g of water, i.e. 67 % by weight of the water had been removed from the pit wet lignite without prior evaporation.
The light oily phase was mixed in a distillation flask with the centrifuge residue to form a suspension of oil, gasoline and partially de-hydrated lignite. ~n heating the suspension, an a~eotropic mixture of water and gasoline and subs0quently of water and oil with a low oil portion distilled at a top temperature of 92 to 96 C, Distillation was promoted by blowing in nitrogen. Temporary foaming in the flask was reduced by blowing the nitrogen n laterally.
The distillation process was stopped when a bottom temperature of 210 C was reached. ~fter condensation, the overhead product was separated in-to a reusable gasoline fraction of low oil content and a heavy aqueous layer.
The quantity of water separated amounted to 87 g. The water content of the lignite and oil suspension was 0.8 % by weight.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the conversion of ground hydrous lignite into a pump-able dehydrated suspension of fine ground lignite and oil wherein a) ground hydrous lignite is mixed with oil of a higher boiling point and with a lower boiling hydrocarbon or hydrocarbon fraction to form a pumpable suspension, b) the lignite in the suspension is ground to a grain size of less than 2 mm, c) the suspension is subjected to a pressure of 30 to 80 bar and heated to a temperature of 190 to 240 °C, d) the suspension is maintained under the conditions at step c) for at least 5 minutes, e) the suspension is separated after step d) into a partially de-hydrated lignite and oil slurry and a water, hydrocarbon and oil liquid, f) the lignite and oil slurry is mixed with an oily phase obtained in a water, hydrocarbon and oil separation step, and g) the lignite and oil slurry is depressurized to 1 to 18 bar at a temperature of 190 to 240°C so as to obtain a dehydrated lignite and oil suspension and a water and hydrocarbon fraction.
2. A process as claimed in claim 1 wherein the separation of step e) is performed in a hydrocyclone.
3. A process as claimed in claim 1 wherein the suspension is cooled after step d) to a temperature matching a maximum vapour pressure of 10 bar, after which the separation of step e) is performed in a centrifuge.
4. A process as claimed in claims 1, 2 or 3 wherein the oil is derived from non refined coal hydrogenation or carbonization products.
5. A process as claimed in claims 1, 2 or 3 wherein the oil is derived from non refined coal hydrogenation or carbonization products and has a boiling range of 250 to 500 °C.
6. A process as claimed in claims 1, 2 or 3 wherein the boiling range of the lower boiling hydrocarbon or hydrocarbon fraction is 110 to 140 °C.
7. A process as claimed in claims 1, 2 or 3 wherein the lower boiling hydrocarbon or hydrocarbon fraction is gasoline of a boiling range of 110 to 140 °C.
8. A process as claimed in claim 1 wherein the weight ratio of the components of the non dehydrated suspension consisting of lignite, oil and the hydrocarbon or hydrocarbon fraction is 1 : 1 : 0.25 to 1 : 1.8 : 0.10, referring to dry lignite.
9. A process as claimed in claim 1 wherein evaporation is carried out in a stripper and the stripper is sustained by blowing in inert gas.
10. A process as claimed in claim 9 wherein liquid foaming in the stripper is reduced by blowing in the inert gas laterally.
11. A process as claimed in claim 9 or 10 wherein the inert gas is nitrogen or carbon dioxide.
12. A process as claimed in claim 1, 2 or 3 wherein the lower boiling hydrocarbon or hydrocarbon fraction is a gasoline fraction which is recycled after distillation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3120602.6 | 1981-05-23 | ||
| DE3120602A DE3120602C2 (en) | 1981-05-23 | 1981-05-23 | "Process for converting ground, water-containing lignite into a pumpable, dehydrated suspension of finely ground lignite and oil" |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1172193A true CA1172193A (en) | 1984-08-07 |
Family
ID=6133077
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000403490A Expired CA1172193A (en) | 1981-05-23 | 1982-05-21 | Process for the conversion of ground hydrous lignite into a pumpable dehydrated suspension of fine-ground lignite and oil |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4440544A (en) |
| JP (1) | JPS57198796A (en) |
| AU (1) | AU550904B2 (en) |
| CA (1) | CA1172193A (en) |
| DE (1) | DE3120602C2 (en) |
| NZ (1) | NZ200653A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1218526A (en) * | 1983-10-31 | 1987-03-03 | Hironobu Shinohara | Slurry composition of solid fuel |
| US4705533A (en) * | 1986-04-04 | 1987-11-10 | Simmons John J | Utilization of low rank coal and peat |
| US20100256430A1 (en) * | 2007-11-15 | 2010-10-07 | Solray Energy Limited | System and process for the treatment of raw material |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1390228A (en) * | 1919-08-05 | 1921-09-06 | Bates Lindon Wallace | Fuel and method of producing same |
| US1390232A (en) * | 1920-04-12 | 1921-09-06 | Lindon W Bates | Liquid fuel and method of manufacturing it |
| US1939587A (en) * | 1931-11-02 | 1933-12-12 | Cunard Steam Ship Company Ltd | Dispersions of coal in oil |
| US2162200A (en) * | 1935-05-24 | 1939-06-13 | Ig Farbenindustrie Ag | Process of preparing dispersions of coal and oil |
| US4014661A (en) * | 1975-03-17 | 1977-03-29 | Texaco Inc. | Fuel making process |
| JPS54163780A (en) * | 1978-06-16 | 1979-12-26 | Kawasaki Heavy Ind Ltd | Solid and liquid stirring * milling and separating apparatus |
| DE2831024A1 (en) * | 1978-07-14 | 1980-01-24 | Metallgesellschaft Ag | METHOD FOR GENERATING A SUSPENSION OF BROWN CHARCOAL AND OIL FOR HYDRATION |
| US4239496A (en) * | 1978-12-06 | 1980-12-16 | Comco | Gas cycle fluid energy process for forming coal-in-oil mixtures |
| AU530284B2 (en) * | 1979-07-20 | 1983-07-07 | Mitsui Kozan Chemicals Co. Ltd. | Treating water containing coal |
| US4265637A (en) * | 1980-01-16 | 1981-05-05 | Conoco, Inc. | Process for preparing blending fuel |
-
1981
- 1981-05-23 DE DE3120602A patent/DE3120602C2/en not_active Expired
-
1982
- 1982-05-18 NZ NZ200653A patent/NZ200653A/en unknown
- 1982-05-19 AU AU83846/82A patent/AU550904B2/en not_active Ceased
- 1982-05-21 US US06/380,998 patent/US4440544A/en not_active Expired - Fee Related
- 1982-05-21 JP JP57085074A patent/JPS57198796A/en active Pending
- 1982-05-21 CA CA000403490A patent/CA1172193A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3120602A1 (en) | 1982-12-16 |
| JPS57198796A (en) | 1982-12-06 |
| DE3120602C2 (en) | 1983-11-17 |
| NZ200653A (en) | 1985-12-13 |
| AU8384682A (en) | 1982-12-02 |
| US4440544A (en) | 1984-04-03 |
| AU550904B2 (en) | 1986-04-10 |
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