CA1127846A - Upgrading fuel fines by pressurized heating - Google Patents
Upgrading fuel fines by pressurized heatingInfo
- Publication number
- CA1127846A CA1127846A CA351,160A CA351160A CA1127846A CA 1127846 A CA1127846 A CA 1127846A CA 351160 A CA351160 A CA 351160A CA 1127846 A CA1127846 A CA 1127846A
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- CA
- Canada
- Prior art keywords
- water
- bodies
- fuel
- fines
- upgrading
- 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
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10F—DRYING OR WORKING-UP OF PEAT
- C10F5/00—Drying or de-watering peat
-
- 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
- C10L9/00—Treating solid fuels to improve their combustion
Landscapes
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
- Hydrogen, Water And Hydrids (AREA)
Abstract
A B S T R A C T
PROCESS FOR UPGRADING LOW-GRADE FUEL FINES AND
FUEL SO OBTAINED
A process for upgrading low-grade fuel fines having a particle size of less than 25 mm comprising shaping the fines into coherent bodies and heating these bodies at a temperature of 150-375°C in the presence of water at a pressure which is higher than the vapour pressure of water at the applied temperature.
PROCESS FOR UPGRADING LOW-GRADE FUEL FINES AND
FUEL SO OBTAINED
A process for upgrading low-grade fuel fines having a particle size of less than 25 mm comprising shaping the fines into coherent bodies and heating these bodies at a temperature of 150-375°C in the presence of water at a pressure which is higher than the vapour pressure of water at the applied temperature.
Description
713~6 PROCESS FOR UPGRADING LOW-GRADE FUEL FI~ES A~D
FUEL SO O~TAINED
The invention relates to a process for upgrading low-grade fuel having a particle size of less than 25 ~m.
Solid fuel which contains more than 10% by weight, and more particularly more than 4Q% by weight of bound and/or unbound water (herein referred to as low-grade fuel¦ can suitably be subJected to thermal upgrading. This fuel is designated as low-grade because its weak or crumbly consistency gives it poor handleability and because the calorific value lies too far below that of normally used fuels such as hard coal or oil. Examples of such fuel are young coal ~such as brown coal), peat, lignite, wood and carbon-containing waste (such as compostl.
Young coal, for example, ~enerally contains 40-70% b~ weight of water and peat contains 80-go~ by weight. The water in ~aid ~uels occurs in a number of forms, namely as inherent or absorbed water, as a constituent in compound organic substances, as chemically bound water (for example water of crystallization~ and as potentially present water, i.e. water that forms from chemically bound o~ygen and hydrogen during upgrading of the fuel.
It is desirable to remove these types of water down to desired percentages and to separate them from the fuel, so as to raise the calorific value and to improve handleability. As a result of such treatment the fuel ~comes less eYpensive to transport and its com-bustion properties are improved.
There are various ways of upgrading low-grade fuel, the most commonly used route being ther~al upgrading. Examples of the various possibilities of achieving thermal upgrading include:
- The fuel can be dried (heating at atmospheric pressure at a temperature below 150 C~, as a result of which the inherent water and the absorbed water is driven off and evaporated. This requires a relati~el~ large amount of energ~ (heat of evapo-rat;onl and in most cases only produces a partial reduction of the water content of the fuel~ In general, the water driven 7~
off will ;n the course of time be reabsorbed.
- Th fuel can be subJected to such heating (suitabl~ between ~50 and 25QC~ that a,thermal upgrading takes place as a result of which chem;cally bound water is eliminated from the fuel and cannot be reabsorbed. This thermal upgrading can be carried out under conditions in which the water to be removed evaporates (and this required additional energy, in the form of heat evaporation~ or at such a pressure that the water remains liquid (so that a physical separation between a solid and a liquid phase becomes necessary~.
- The fuel can be subjected to a treatment under more drastic conditions, under which organic substances such as acids, salts and esters are partly decomposed, such as by decarboxylation (separation of carbon dioxide). An oreanic substance (for ex-ample R.COOH) comprising an oxygen-containing group (for ex ample a carboxyl group, i.e. COOH) can split off carbon dioxide ~hile the hydrogen is becoming attached to the remaining carbon chain (Por example: R.COOH ~ RH ~ C02~. ~his decom-position occurs at higher temperatures - in particular above 350 C - and is accompanied by a drastic structural change of the fuel. Carboxylation, for example, causes fuel to become hydrophobic instead of hydrophilic, since the decarboxylation causes the polar oxygen-containing groups, whicn gave the fuel its hydrophilic character, to disappear.
An advantage of thermal upgrading in the presence of water (at a pressure higher than the water vapour pressure at the selected temperature~ is that the formation of gas from the fuel (largely as a result of decarboxylation) already begins at 3QO CJ whereas under dry condiiions (at a pressure lower than the water vapour pressure at the selected temperature~ the formation of gas is fairly irsig nificant below 40QC.
In the past a num~er of proposals have been made en~isaging an economically acceptable upgrading, and the App1icant itself has also proposed a process of the t~pe mentioned in the preamble (see U.K.
patent specification No. ],4~],94~. In said process, uhich is of the slurry type, finely divided fuel is mixed with water into a .
;.
. . .
' pumpable slurry, and the slurry is heated at high pressure until upgrading occurs. Besides a number of advantages, said slurr~
process has the inherent drawback that the added quantity of water also has to be heated. Nevertheless, it has attracted wide interest from variou3 quarters.
The present invention does not relate to the above-mentioned slurry process, but to a fi.~ed-bed process which has been ~nown for some time and in which the fuel, not in a pumpable slurry but es-sentially without additional water, is heated in a fixed bed under such conditions that the driven-off water remains liquid. In this description, fixed bed-type processes include all processes in which a charge of solid fuel or a continuous stream of solid fuel is heated without the charge first having been converted into a pumpable slurry in water. Such processes may, for example, make use of a fixed bed, a moving bed or a fluidized bed.
An example of such a fixed-bed process is the Fleissner process, which essentially comprises the heating :in a vessel of a quantity of fuel (see US patent specification No. 1,632,ô29 and Industrial and Engineering Chemistry, December ~930 (Vol. 22, No. ~2, pp. 1347-1360)). The fuel is present in a fixed bed and is heated b~ passingsaturated steam into the vessel, which steam partially condenses.
The condensed steam and the water originating from the fuel percolate downwards through the fixed bed and are drained off at the bottom of the vessel. Said process is used on a considerable scale in practice.
The invention relates to such a process, in which on the one hand liquid water is indeed present during the heating, but on the other hand, there is so little water that the charge to be heated is in the solid state.
In the "fixed-bed" processes of the Fleissner type, the fuel in 3Q the reactor in which the heating takes place must ha~e as uniform as possible a particle size, which size is situated between certain limits. T~e upper limit is im~osed by the requirement that the tElrou~h-heat time must ~e sufficiently short, i.e. that the interior of the largest particles must be capa~le of ~eing heated to the re~uired temperature sufficiently fast to arrive at an economic process. The lower limit is imposed by the requirement that the : : .
~ ~278~
smallest particles must not be washed out of the bed and by the fact that the proportion of inherent moisture increases with the percentage of small ~uel particles (drainage from the bed deteriorates).
Certain fuels become available with too small a particle size, and they are not suitable for the Fleissner process. Other fuels contain a fraction, often considerable, with too large particles. Reduction (for example, by grinding or crushing) always yields, in addition to a usable fraction, a fraction fines with too small particles which, hitherto, could not be utilized in the fixed bed-type process. It will be clear that these fines represent a loss, since they collect a considerably lower return than upgraded fuel.
me object of the present invention is to change this situation and to provide a fixed bed-type process for the up-grading of fuel fines.
According to the invention low grade fuel fines hav-ing a particle size of less than 25 mm are upgraded by shaping the fines into cohexent bodies and heating these bodies at a temperature of 150-375C. in the presence of water at a pres-sure which is higher than the vapour press~re of water at the applied temperature. ^~
More particularly the invention provides a process for the upgrading of low-grade fuel ~ines having a water con-tent of at least 10% by weight and a particle size of less than 25 mm, in which the fines are shaped into coherent bodies, the said bodies are heated in a fixed bed to a temperature of 150-375C. in the presence of the water originally present in the fuel fines, at a pressure which is higher than the vapour pressure of water at the selected temperature, and the water is drained off.
It has been found that the coherent bodies do not lose their initial strength during thermal upgrading and mostly even become considerably stronger. A possible explanation of this is that during the upgrading treatment some tar is formed, which might act as the binder. Of course, the bodies must possess a certain minimum "green '` strength before thermal upgrading, in order that they can be passed ' ~L~2~
- 4a -without disintegrating to the apparatus in which they are subjected to the thermal upgrading treatment.
A very important advantage of the process accord-ing to the invention is that the separation of the up-graded fuel and the driven-off water is much simpler and cheaper and that the upgraded end product is obtained in convenient form and does not dust.
In practice, it has been found that the require-ment of a certain minimum '`green" strength can be met in a number of ways. The bodies may, for example, be obtained by extruding, by briquetting, by pressing (tablet making) and by compaction (ramming).
.
....
78~
A very attractiYe method in which the shaping of the bodies can be combined with their suppl~ to the space in which the upgrading treatment takes place, consists of suppl~ing the fines to the up-grading space via an extrusion press or via a solids pump for over-coming high pressure.
~ he pressure which is applîed ~or the purpose of shaping the bodies depends inter alia on the type of fuel, but it is usuall~
between 0.1 and 25 kN/cm and preferably between 1 and ~5 ~/cm .
Although the application of a higher pressure will be corres-pondingly more expensive, it often yields the advantage of a greaterstrength and possibl~ partial dewatering when the bodies are shaped.
According to the invention, it is preferred to shape bodies having a largest dimension between 10 and 150 mm. On the one hand, such bodies give a sufficientl~ rapid upgrading and, on the other, they present no problem when separating the formed water from the bodies. It is preferred that during the heating of the bodies no fines are present having a particle size of less than 5 mm and preferably less than 10 mm.
In this connection it is noted that it wilL be clear that in all cases the bodies will be larger than the particles of which they are composed, so that the lower limit of 10 mm only applies to bodies made of particles having a smaller size.
If the "green" strength of the bodies is not satisfactory, according to the invention a binder can be added to the ~ines before the bodies are shaped. ~xamples of such binders are bitumen, residual petroleum ~ractions, and coal tar.
A principle known per se can be advantageousl~ applied to the present invention, namely that after the heating of the bodies and removal of the liquid water, the pressure in the upgrading space is reduced and/or the temperature is raised so that steam ~orms, thereby promoting the decarbQx~lation and facilitating the separation of fuel and water. During this second heating period under the changed conditions, the upgrading treatment is continued.
~he invention will now be elucidated with reference to two speciDic e~xamples o~ a process according to the inYention.
- .
~ :~ :: . . ~: :
:: ::
'~:: , :: ,,:.. : . :
...
84~;
E~PLE ~
.
A ~uantity of Yictoria brown coal (an Australian brown coal haYing a water content of 53.,% by weight and a calorific Yalue of 3078 cal/g~ ~as compacted at a pressure of 5. Q kN~cm to form 5 cushion-shaped tablets haYing a largest diameter of 11. 4 mm.
A quantity of 553.8 g of tablets was heated at a temperature of 250 C for 60 minutes at a pressure of 45 bar; during heating the tablets remained in contact with the separating water, which remained liquid (the water vapour pressure at 250 C is approx. 40 bar~. The formed water was subsequentl~ drained off.
Next the tablets were heated for 60 minutes at 360 C at a pressure of 40 bar, during which treatment all the present water and all the forming separating water was in the vapour state (the water vapour pressure at 360C is approx. 190 bar~.
During both treatments the tablets remained intact, but con-siderable crimping occurred: after the treatment the tablets were reduced to only 37% of their original volumes (the largest tablet dimension was now 8.2 mm~.
Upgrading may therefore be said to have taken place with regard to transportability (the fuel takes up considerabl~v less space). The product has also been upgraded with regard to its combustion proper-ties, since the calorific Yalue of the fuel after the treatment was 7600 cal/g (which is more than double the original value~.
The following mass balance can be given for this experiment:
The tablets originall~ consisted of 256 g dry coal and 298 g water. After completion of the treatment there remained 207. 3 g of end product, 17.75 1 o~ gas was ~ormed (principall~ C02~ - which corresponds to a consumption of approx. 35 g = ~ 3.5~ of the dry coal of the starting product, and approx. 5.5% of the dr~ coal of the starting product was conYerted into tar. The end product therefore contained ~9% by weight of dry coal less than the starting product.
From this mass balance the ~ollowing energ~ balance can be calculated:
The starting product, namely 553.8 g, had a calorific capacit~Y
of 553.8 x 3078 cal = 17Q5 kcal.
~L~l2~8~
The end product, namely 2Q7.3 g, had a calorific capacity of 2Q7.3 ~ 7600 cal = ~575 kcal.
The end product therefore still represented ~2.~ of the calo-rific capacity of the starting product, concentrated into 3~% of the original volume and into 3~.4% of the original weight. Upgrading may therefore most certainl~ be said to have taken place.
The water content of the treated tablets was approx. ~% by weight.
In order to obtain an idea of the strength of the tablets in the various stages, the loads at which the tablets began to burst under a press were determined:
- the "green" strength of the untreated tablets was 4.0 ~;
- the strength of the tablets after the treatment at 250C was 7.5 N; and 15 - the strength of the tablets after treatment at 360 C was 29.8 ~.
This demonstrates clearl~ that the strength of the tablets increases as a result of the upgrading treatment, which can be a great advantage in subsequent processing. Incidentally, the strength of lumps of the same brown coal (untreated~ was 4.2 N.
In order to obtain an idea o$ the dusting properties of the treated brown coal, the tablets were subjected to a drop shatter test (modified ASTM D 440~. In this, the elements to be tested are dropped a number of times in a conditioned manner and after the tes-t the weight percentage o$ the fraction of small particles in the residues is analysed:
- o$ tablets heated onl~ to 250 C, 33.0% by weight shattered into particles smaller than 2 mm:
- of tablets additionally heated at 360 C, onl~ 6.3% by weight shattered into particles smaller than 2 mm, and 3Q - of lumps of brown coal of comparable dimensions which nad been thermally dried, 84.Q% b~ ~eight shattered into particles smaller than 2 mm.
This shows clearl~ that upgrading may also be said to have taken place with regard to the dusting properties and handleability.
~,i: ' ~ :
:
3~;
A quantity of Morwell brown coal (an Austral;an brown coal having a water content of 61.2~ by weight and a calorific value of 2600 cal/g~ was compacted at a pressure of 5.0 ~cm to form uniform tablets (the same dimensions as in Example ~. The tablets were then heated at 340 C at a pressure o~ ~56 bar for 1 minute (the vapour pressure of water at 340 C is approx. ]49 bar~ in the presence of some inherent moisture.
During this -treatment there was a crimping of 40% and approx.
12% of the dry coal was lost during the treatment.
The end product had a water content of 34.6~ by weight and a calorific value of 4960 cal/g.
Here again, upgrading may therefore be said to have taken place, since the volume was decreased by 40% and the calorific value was more than doubled.
Incidentally, the water content of the brown coal is still considerable and capable of ~urther improvement.
In a drop shatter test, 1.9% by weight of the upgraded tablets shattered into a fraction smaller than 1.18 mm, while of upgraded brown coal lumps (particle si~e 7.5-12 ~nm~ a quantity of 6.9% by weight shattered into a fraction smalle:r than 1.18 mm.
This shows that even an upgrading treatment of short duration produces strong tablets and a reduction in water content.
: ~ .
: ~
FUEL SO O~TAINED
The invention relates to a process for upgrading low-grade fuel having a particle size of less than 25 ~m.
Solid fuel which contains more than 10% by weight, and more particularly more than 4Q% by weight of bound and/or unbound water (herein referred to as low-grade fuel¦ can suitably be subJected to thermal upgrading. This fuel is designated as low-grade because its weak or crumbly consistency gives it poor handleability and because the calorific value lies too far below that of normally used fuels such as hard coal or oil. Examples of such fuel are young coal ~such as brown coal), peat, lignite, wood and carbon-containing waste (such as compostl.
Young coal, for example, ~enerally contains 40-70% b~ weight of water and peat contains 80-go~ by weight. The water in ~aid ~uels occurs in a number of forms, namely as inherent or absorbed water, as a constituent in compound organic substances, as chemically bound water (for example water of crystallization~ and as potentially present water, i.e. water that forms from chemically bound o~ygen and hydrogen during upgrading of the fuel.
It is desirable to remove these types of water down to desired percentages and to separate them from the fuel, so as to raise the calorific value and to improve handleability. As a result of such treatment the fuel ~comes less eYpensive to transport and its com-bustion properties are improved.
There are various ways of upgrading low-grade fuel, the most commonly used route being ther~al upgrading. Examples of the various possibilities of achieving thermal upgrading include:
- The fuel can be dried (heating at atmospheric pressure at a temperature below 150 C~, as a result of which the inherent water and the absorbed water is driven off and evaporated. This requires a relati~el~ large amount of energ~ (heat of evapo-rat;onl and in most cases only produces a partial reduction of the water content of the fuel~ In general, the water driven 7~
off will ;n the course of time be reabsorbed.
- Th fuel can be subJected to such heating (suitabl~ between ~50 and 25QC~ that a,thermal upgrading takes place as a result of which chem;cally bound water is eliminated from the fuel and cannot be reabsorbed. This thermal upgrading can be carried out under conditions in which the water to be removed evaporates (and this required additional energy, in the form of heat evaporation~ or at such a pressure that the water remains liquid (so that a physical separation between a solid and a liquid phase becomes necessary~.
- The fuel can be subjected to a treatment under more drastic conditions, under which organic substances such as acids, salts and esters are partly decomposed, such as by decarboxylation (separation of carbon dioxide). An oreanic substance (for ex-ample R.COOH) comprising an oxygen-containing group (for ex ample a carboxyl group, i.e. COOH) can split off carbon dioxide ~hile the hydrogen is becoming attached to the remaining carbon chain (Por example: R.COOH ~ RH ~ C02~. ~his decom-position occurs at higher temperatures - in particular above 350 C - and is accompanied by a drastic structural change of the fuel. Carboxylation, for example, causes fuel to become hydrophobic instead of hydrophilic, since the decarboxylation causes the polar oxygen-containing groups, whicn gave the fuel its hydrophilic character, to disappear.
An advantage of thermal upgrading in the presence of water (at a pressure higher than the water vapour pressure at the selected temperature~ is that the formation of gas from the fuel (largely as a result of decarboxylation) already begins at 3QO CJ whereas under dry condiiions (at a pressure lower than the water vapour pressure at the selected temperature~ the formation of gas is fairly irsig nificant below 40QC.
In the past a num~er of proposals have been made en~isaging an economically acceptable upgrading, and the App1icant itself has also proposed a process of the t~pe mentioned in the preamble (see U.K.
patent specification No. ],4~],94~. In said process, uhich is of the slurry type, finely divided fuel is mixed with water into a .
;.
. . .
' pumpable slurry, and the slurry is heated at high pressure until upgrading occurs. Besides a number of advantages, said slurr~
process has the inherent drawback that the added quantity of water also has to be heated. Nevertheless, it has attracted wide interest from variou3 quarters.
The present invention does not relate to the above-mentioned slurry process, but to a fi.~ed-bed process which has been ~nown for some time and in which the fuel, not in a pumpable slurry but es-sentially without additional water, is heated in a fixed bed under such conditions that the driven-off water remains liquid. In this description, fixed bed-type processes include all processes in which a charge of solid fuel or a continuous stream of solid fuel is heated without the charge first having been converted into a pumpable slurry in water. Such processes may, for example, make use of a fixed bed, a moving bed or a fluidized bed.
An example of such a fixed-bed process is the Fleissner process, which essentially comprises the heating :in a vessel of a quantity of fuel (see US patent specification No. 1,632,ô29 and Industrial and Engineering Chemistry, December ~930 (Vol. 22, No. ~2, pp. 1347-1360)). The fuel is present in a fixed bed and is heated b~ passingsaturated steam into the vessel, which steam partially condenses.
The condensed steam and the water originating from the fuel percolate downwards through the fixed bed and are drained off at the bottom of the vessel. Said process is used on a considerable scale in practice.
The invention relates to such a process, in which on the one hand liquid water is indeed present during the heating, but on the other hand, there is so little water that the charge to be heated is in the solid state.
In the "fixed-bed" processes of the Fleissner type, the fuel in 3Q the reactor in which the heating takes place must ha~e as uniform as possible a particle size, which size is situated between certain limits. T~e upper limit is im~osed by the requirement that the tElrou~h-heat time must ~e sufficiently short, i.e. that the interior of the largest particles must be capa~le of ~eing heated to the re~uired temperature sufficiently fast to arrive at an economic process. The lower limit is imposed by the requirement that the : : .
~ ~278~
smallest particles must not be washed out of the bed and by the fact that the proportion of inherent moisture increases with the percentage of small ~uel particles (drainage from the bed deteriorates).
Certain fuels become available with too small a particle size, and they are not suitable for the Fleissner process. Other fuels contain a fraction, often considerable, with too large particles. Reduction (for example, by grinding or crushing) always yields, in addition to a usable fraction, a fraction fines with too small particles which, hitherto, could not be utilized in the fixed bed-type process. It will be clear that these fines represent a loss, since they collect a considerably lower return than upgraded fuel.
me object of the present invention is to change this situation and to provide a fixed bed-type process for the up-grading of fuel fines.
According to the invention low grade fuel fines hav-ing a particle size of less than 25 mm are upgraded by shaping the fines into cohexent bodies and heating these bodies at a temperature of 150-375C. in the presence of water at a pres-sure which is higher than the vapour press~re of water at the applied temperature. ^~
More particularly the invention provides a process for the upgrading of low-grade fuel ~ines having a water con-tent of at least 10% by weight and a particle size of less than 25 mm, in which the fines are shaped into coherent bodies, the said bodies are heated in a fixed bed to a temperature of 150-375C. in the presence of the water originally present in the fuel fines, at a pressure which is higher than the vapour pressure of water at the selected temperature, and the water is drained off.
It has been found that the coherent bodies do not lose their initial strength during thermal upgrading and mostly even become considerably stronger. A possible explanation of this is that during the upgrading treatment some tar is formed, which might act as the binder. Of course, the bodies must possess a certain minimum "green '` strength before thermal upgrading, in order that they can be passed ' ~L~2~
- 4a -without disintegrating to the apparatus in which they are subjected to the thermal upgrading treatment.
A very important advantage of the process accord-ing to the invention is that the separation of the up-graded fuel and the driven-off water is much simpler and cheaper and that the upgraded end product is obtained in convenient form and does not dust.
In practice, it has been found that the require-ment of a certain minimum '`green" strength can be met in a number of ways. The bodies may, for example, be obtained by extruding, by briquetting, by pressing (tablet making) and by compaction (ramming).
.
....
78~
A very attractiYe method in which the shaping of the bodies can be combined with their suppl~ to the space in which the upgrading treatment takes place, consists of suppl~ing the fines to the up-grading space via an extrusion press or via a solids pump for over-coming high pressure.
~ he pressure which is applîed ~or the purpose of shaping the bodies depends inter alia on the type of fuel, but it is usuall~
between 0.1 and 25 kN/cm and preferably between 1 and ~5 ~/cm .
Although the application of a higher pressure will be corres-pondingly more expensive, it often yields the advantage of a greaterstrength and possibl~ partial dewatering when the bodies are shaped.
According to the invention, it is preferred to shape bodies having a largest dimension between 10 and 150 mm. On the one hand, such bodies give a sufficientl~ rapid upgrading and, on the other, they present no problem when separating the formed water from the bodies. It is preferred that during the heating of the bodies no fines are present having a particle size of less than 5 mm and preferably less than 10 mm.
In this connection it is noted that it wilL be clear that in all cases the bodies will be larger than the particles of which they are composed, so that the lower limit of 10 mm only applies to bodies made of particles having a smaller size.
If the "green" strength of the bodies is not satisfactory, according to the invention a binder can be added to the ~ines before the bodies are shaped. ~xamples of such binders are bitumen, residual petroleum ~ractions, and coal tar.
A principle known per se can be advantageousl~ applied to the present invention, namely that after the heating of the bodies and removal of the liquid water, the pressure in the upgrading space is reduced and/or the temperature is raised so that steam ~orms, thereby promoting the decarbQx~lation and facilitating the separation of fuel and water. During this second heating period under the changed conditions, the upgrading treatment is continued.
~he invention will now be elucidated with reference to two speciDic e~xamples o~ a process according to the inYention.
- .
~ :~ :: . . ~: :
:: ::
'~:: , :: ,,:.. : . :
...
84~;
E~PLE ~
.
A ~uantity of Yictoria brown coal (an Australian brown coal haYing a water content of 53.,% by weight and a calorific Yalue of 3078 cal/g~ ~as compacted at a pressure of 5. Q kN~cm to form 5 cushion-shaped tablets haYing a largest diameter of 11. 4 mm.
A quantity of 553.8 g of tablets was heated at a temperature of 250 C for 60 minutes at a pressure of 45 bar; during heating the tablets remained in contact with the separating water, which remained liquid (the water vapour pressure at 250 C is approx. 40 bar~. The formed water was subsequentl~ drained off.
Next the tablets were heated for 60 minutes at 360 C at a pressure of 40 bar, during which treatment all the present water and all the forming separating water was in the vapour state (the water vapour pressure at 360C is approx. 190 bar~.
During both treatments the tablets remained intact, but con-siderable crimping occurred: after the treatment the tablets were reduced to only 37% of their original volumes (the largest tablet dimension was now 8.2 mm~.
Upgrading may therefore be said to have taken place with regard to transportability (the fuel takes up considerabl~v less space). The product has also been upgraded with regard to its combustion proper-ties, since the calorific Yalue of the fuel after the treatment was 7600 cal/g (which is more than double the original value~.
The following mass balance can be given for this experiment:
The tablets originall~ consisted of 256 g dry coal and 298 g water. After completion of the treatment there remained 207. 3 g of end product, 17.75 1 o~ gas was ~ormed (principall~ C02~ - which corresponds to a consumption of approx. 35 g = ~ 3.5~ of the dry coal of the starting product, and approx. 5.5% of the dr~ coal of the starting product was conYerted into tar. The end product therefore contained ~9% by weight of dry coal less than the starting product.
From this mass balance the ~ollowing energ~ balance can be calculated:
The starting product, namely 553.8 g, had a calorific capacit~Y
of 553.8 x 3078 cal = 17Q5 kcal.
~L~l2~8~
The end product, namely 2Q7.3 g, had a calorific capacity of 2Q7.3 ~ 7600 cal = ~575 kcal.
The end product therefore still represented ~2.~ of the calo-rific capacity of the starting product, concentrated into 3~% of the original volume and into 3~.4% of the original weight. Upgrading may therefore most certainl~ be said to have taken place.
The water content of the treated tablets was approx. ~% by weight.
In order to obtain an idea of the strength of the tablets in the various stages, the loads at which the tablets began to burst under a press were determined:
- the "green" strength of the untreated tablets was 4.0 ~;
- the strength of the tablets after the treatment at 250C was 7.5 N; and 15 - the strength of the tablets after treatment at 360 C was 29.8 ~.
This demonstrates clearl~ that the strength of the tablets increases as a result of the upgrading treatment, which can be a great advantage in subsequent processing. Incidentally, the strength of lumps of the same brown coal (untreated~ was 4.2 N.
In order to obtain an idea o$ the dusting properties of the treated brown coal, the tablets were subjected to a drop shatter test (modified ASTM D 440~. In this, the elements to be tested are dropped a number of times in a conditioned manner and after the tes-t the weight percentage o$ the fraction of small particles in the residues is analysed:
- o$ tablets heated onl~ to 250 C, 33.0% by weight shattered into particles smaller than 2 mm:
- of tablets additionally heated at 360 C, onl~ 6.3% by weight shattered into particles smaller than 2 mm, and 3Q - of lumps of brown coal of comparable dimensions which nad been thermally dried, 84.Q% b~ ~eight shattered into particles smaller than 2 mm.
This shows clearl~ that upgrading may also be said to have taken place with regard to the dusting properties and handleability.
~,i: ' ~ :
:
3~;
A quantity of Morwell brown coal (an Austral;an brown coal having a water content of 61.2~ by weight and a calorific value of 2600 cal/g~ was compacted at a pressure of 5.0 ~cm to form uniform tablets (the same dimensions as in Example ~. The tablets were then heated at 340 C at a pressure o~ ~56 bar for 1 minute (the vapour pressure of water at 340 C is approx. ]49 bar~ in the presence of some inherent moisture.
During this -treatment there was a crimping of 40% and approx.
12% of the dry coal was lost during the treatment.
The end product had a water content of 34.6~ by weight and a calorific value of 4960 cal/g.
Here again, upgrading may therefore be said to have taken place, since the volume was decreased by 40% and the calorific value was more than doubled.
Incidentally, the water content of the brown coal is still considerable and capable of ~urther improvement.
In a drop shatter test, 1.9% by weight of the upgraded tablets shattered into a fraction smaller than 1.18 mm, while of upgraded brown coal lumps (particle si~e 7.5-12 ~nm~ a quantity of 6.9% by weight shattered into a fraction smalle:r than 1.18 mm.
This shows that even an upgrading treatment of short duration produces strong tablets and a reduction in water content.
: ~ .
: ~
Claims (8)
- The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-l. A process for the upgrading of low-grade fuel fines having a water content of at least 10% by weight and a particle size of less than 25 mm, in which the fines are shaped into coherent bodies, the said bodies are heated in a fixed bed to a temperature of 150-375°C
in the presence of the water originally present in the fuel fines, at a pressure which is higher than the vapour pressure of water at the selected temperature, and the water is drained off. - 2. A process as claimed in claim 1, in which the bodies are obtained by extruding, briquetting, pressing or compacting.
- 3. A process as claimed in claim 1, in which the bodies are shaped at a pressure of 0.1-25 kN/cm2.
- 4. A process as claimed in claim 3, in which the bodies are shaped at a pressure of 1-15kN/cm2. .
- 5. A process as claimed in claim l, 2 or 3, in which bodies are shaped having a largest dimension between 10 and 150 mm.
- 6. A process as claimed in claim 1, 2 or 3, in which a binder is added to the fines before the bodies are shaped.
- 7. A process as claimed in claim l, 2 or 3, in which during the heating of the bodies no fines are present having a particle size of less than 5 mm.
- 8. A process as claimed in claim l, 2 or 3, in which during the heating of the bodies no fines are present having a particle size of less than 10 mm.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7919268 | 1979-06-01 | ||
| GB7919268 | 1979-06-01 | ||
| NL7905586A NL7905586A (en) | 1979-07-18 | 1979-07-18 | Upgrading of solid fuel fines - by shaping and heating in contact with liq. water |
| NL7905586 | 1979-07-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1127846A true CA1127846A (en) | 1982-07-20 |
Family
ID=26271747
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA351,160A Expired CA1127846A (en) | 1979-06-01 | 1980-05-02 | Upgrading fuel fines by pressurized heating |
Country Status (12)
| Country | Link |
|---|---|
| EP (1) | EP0019969B1 (en) |
| AR (1) | AR220984A1 (en) |
| AU (1) | AU532194B2 (en) |
| BR (1) | BR8003335A (en) |
| CA (1) | CA1127846A (en) |
| ES (1) | ES8102181A1 (en) |
| GR (1) | GR68474B (en) |
| NZ (1) | NZ193870A (en) |
| PL (1) | PL132146B1 (en) |
| RO (1) | RO82629A (en) |
| TR (1) | TR21086A (en) |
| YU (1) | YU40878B (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE195653C (en) * | ||||
| GB191313924A (en) * | 1913-06-16 | 1914-06-11 | James Anderson | A Continuous Process for Treating by Steam and Converting into Fuel of a High Calorific Value Moist Organic Matter of Vegetable Origin. |
| US1632829A (en) * | 1924-08-14 | 1927-06-21 | Fleissner Hans | Method of drying coal and the like |
| DE899493C (en) * | 1950-08-14 | 1953-12-14 | Josef Schmitz Dipl Chem | Method of treating peat |
| AU430626B2 (en) * | 1968-01-26 | 1972-11-26 | Universityof Melbourne | Separation of water from solid organic materials |
| GB1471949A (en) * | 1974-06-19 | 1977-04-27 | Shell Int Research | Process for the upgrading of coal or the like |
-
1980
- 1980-05-02 CA CA351,160A patent/CA1127846A/en not_active Expired
- 1980-05-14 EP EP19800200456 patent/EP0019969B1/en not_active Expired
- 1980-05-27 YU YU142780A patent/YU40878B/en unknown
- 1980-05-28 AU AU58830/80A patent/AU532194B2/en not_active Ceased
- 1980-05-28 NZ NZ19387080A patent/NZ193870A/en unknown
- 1980-05-28 RO RO80101257A patent/RO82629A/en unknown
- 1980-05-28 GR GR62063A patent/GR68474B/el unknown
- 1980-05-28 AR AR28121680A patent/AR220984A1/en active
- 1980-05-28 BR BR8003335A patent/BR8003335A/en unknown
- 1980-05-28 ES ES491904A patent/ES8102181A1/en not_active Expired
- 1980-05-28 TR TR2108680A patent/TR21086A/en unknown
- 1980-05-28 PL PL22456480A patent/PL132146B1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GR68474B (en) | 1982-01-04 |
| TR21086A (en) | 1983-06-29 |
| EP0019969A1 (en) | 1980-12-10 |
| EP0019969B1 (en) | 1984-03-14 |
| NZ193870A (en) | 1982-08-17 |
| RO82629A (en) | 1983-11-01 |
| BR8003335A (en) | 1980-12-30 |
| AR220984A1 (en) | 1980-12-15 |
| AU5883080A (en) | 1980-12-04 |
| PL224564A1 (en) | 1981-02-13 |
| RO82629B (en) | 1983-10-30 |
| YU142780A (en) | 1983-02-28 |
| ES491904A0 (en) | 1980-12-16 |
| AU532194B2 (en) | 1983-09-22 |
| PL132146B1 (en) | 1985-02-28 |
| YU40878B (en) | 1986-08-31 |
| ES8102181A1 (en) | 1980-12-16 |
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