CA1268444A - Process for improving low-rank coal and apparatus therefor - Google Patents
Process for improving low-rank coal and apparatus thereforInfo
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- CA1268444A CA1268444A CA000500302A CA500302A CA1268444A CA 1268444 A CA1268444 A CA 1268444A CA 000500302 A CA000500302 A CA 000500302A CA 500302 A CA500302 A CA 500302A CA 1268444 A CA1268444 A CA 1268444A
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Abstract
Abstract:
The present invention relates to a process and apparatus for improving low-rank coal. The process for improving low-rank coal comprises the steps of carbonizing low-rank coal, selectively separating a tar-rich gas mixture from the gas produced from the low-rank coal during the carbonization step, and bringing the gas mixture into contact with low-rank coal which has passed the carbonization step and cooled to thereby adhere the tar to the surface of the coal. The apparatus for improving low-rank coal comprises a unit for carbonizing low-rank coal, a unit for cooling low-rank coal which has passed the carbonization step, a unit for selectively separating a tar-rich gas mixture from the gas produced from the low-rank coal during the carbonization step, and a unit for bringing the gas mixture into contact with low-rank coal which has passed the carbonization step and cooled to thereby adhere the tar to the surface of the coal. Thus, the low-rank coal can be improved into coal having a low adherent moisture content and excellent moisture resistance.
The present invention relates to a process and apparatus for improving low-rank coal. The process for improving low-rank coal comprises the steps of carbonizing low-rank coal, selectively separating a tar-rich gas mixture from the gas produced from the low-rank coal during the carbonization step, and bringing the gas mixture into contact with low-rank coal which has passed the carbonization step and cooled to thereby adhere the tar to the surface of the coal. The apparatus for improving low-rank coal comprises a unit for carbonizing low-rank coal, a unit for cooling low-rank coal which has passed the carbonization step, a unit for selectively separating a tar-rich gas mixture from the gas produced from the low-rank coal during the carbonization step, and a unit for bringing the gas mixture into contact with low-rank coal which has passed the carbonization step and cooled to thereby adhere the tar to the surface of the coal. Thus, the low-rank coal can be improved into coal having a low adherent moisture content and excellent moisture resistance.
Description
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Process for improving low-rank coal and apparatus therefo_ This invention relates to a process and apparatus for improving low-rank coal. More particularly the invention relates to a process and apparatus for improving low-rank coal which is suitable for improving low-rank coal into coal having a low adherent water content and excellent moisture resistance.
Known techniques for improving low-rank coal, such as sub-bituminous coal or lignite, into coal of excellent moisture resistance include, for example, a process described in Japanese Patent Publication No. 115965/1982.
Such a process comprises quickly heating low-rank coal to a final heating temperature of 300 to 500C at a rate of temperature rise of at least 100C/min and quickly cooling the coal to a temperature of 250C or below at a rate of temperature fall of 50C/min or greater to thereby block pores in the coal by solidifying, without allowing evaporation. In this process a liquid tae-like material exudes to the surface of the coal during its thermal cracking, thus decreasing the specific surface area of the coal to thereby decrease the rnoisture absorption of the coal.
However, the tar obtained by such a heat-treatment of coal contains as much as 90~ low-boiling substances (b.p._ 200C). As a result, the gasification rate of the tar is so high that it is extremely difficult to solidify . ,, ,~, . ':.~ ' ~: '' '` ;
.,. :, , . -. .
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- the tar exuding to the surface of the coal before its gasification. Therefore, there is a problem in decreasing the moisture absorption of coal, that is, improving it into coal of excellent moisture resistance.
It is an object of this invention ~o provide a process and an apparatus for improving low-rank coal into coal having a low adherent moisture content and excellent moisture resistance by bringing a tar-rich gas mixture selectively separated from a gas mixture produced from the low-rank coal during a step of carbonizing it into contact with low-rank coal which has passed the carbonization step and thereby adhering the tar to the low-rank coal.
In accordance with an aspect of the invention, there is provided a process for improving low-rank coal, comprising a step of first-stage carbonizing said low-rank coal at a temperature at which it generates a moisture-rich gas mix-ture, a step of second-stage carbonizing said low-rank coal, which has passed the first-stage carbonization step, at a temperature at which it generates a tar-rich gas mixture, a step of cooling said low-rank coal which has passed the second-stage carbonization step, and a step of bringing the tar-rich gas mixture into contact with said cooled low-rank coal to thereby adhere the tar to said cooled low-rank coal.
In accordance with another aspect of the invention there is provided an apparatus for improving low-rank coal, comprising means for first-stage carbonizing said low-rank coal at a temperature at which it generates a moisture-rich gas mixture, means for second-stage carbonizing said low-rank coal, which has passed the first-stage carbonization, at a temperature at which it generates a tar-rich gas mixture, means for cooling said low-rank coal which has passed the second-stage carbonization, and means for bringing the tar-rich gas mixture into contact with said cooled low-rank coal to thereby adhere the tar to said cooled low-rank coal.
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- 2a -Thus, according to this invention, the tar-rich gas mixture selectively separated from the gas produced from low-rank coal during its carbonization step is brought into contact with low-rank coal which has passed the carbonization step, whereby the tar can be adhered to said low-rank coal.
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The present invention will be described in detail hereinbelow with the aid of the accompanying drawings, in which:
Fig. 1 is a flow chart for practicing the present invention and illustrating an example of a process for improving low-rank coal according to this invention;
Figs. 2 to 5 are diagrams of the relationship between the carbonization temperature and the amount of the tar, moisture or decomposition gas produced from low-rank coal during its carbonization;
Fig. 6 is a schematic diagram of a moving-bed carbonization apparatus which is another example of this invention; and Fig. 7 is a diagram showing the distribution of coal temperature within the moving-bed carbonization apparatus.
When low-rank coal such as sub-bit~ninous coal or lignite is carbonized at a temperature of 250 to 450C, hydrophobic coal having a high calorific value can be obtained. In order to highly improve such low-rank coal, it is effective to adhere a tar produced from the low-rank coal during its carbonization step to low-rank coal which has passed the carbonization step (hereinafter referred to as carbonized coal). The inventors of this invention previously proposed a process comprising bringing tar produced from low-rank coal during its carbonization step a~d not separated from entrained moisture into direct contact with carbonized and cooled coal to thereby selectively adhere the tar to the coal tsee Japanese Patent Laid-Open No. 32894/1985~.
However, this process has a disadvantage that when the temperature of the carbonized and cooled coal is low, almost all of the moisture and the tar are adhered to the carbonized coal, which increases the content of adherent moisture. The present invention provides a process and apparatus which decreases the amount of the moisture adhering to the carbonized coal.
. .
. . . .
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,. .. .. , :
:- : ,-. . .:
.-~.: : -A considerable temperature difference existsbetween the carbonization temperature at which moisture begins to be generated from low-rank coal during its carbonization (hereinaEter referred to as moisture S generation-initiating carbonization temperature) and that at which tar begins to be generated from low-rank coal during its carbonization (hereinafter referred to as a tar generation-initiating carbonization temperature).
An example of this invention will now be described with reference to Figs. 1 to 5.
Referring to Fig. 1, low-rank coal A is fed to a dryer 10, such as a direct heating rotary drum, where it is dewatered and dried at a temperature of 80 to 150C.
The low-rank coal which has passed the drying step (here-inafter referred to as dried coal) is withdrawn from thedryer 10 and fed to a first-stage carbonization apparatus 20. Moisture B generated from low-rank coal A during the drying step is withdrawn from the dryer 10 through an exit pipe 11 and discharged from the system. The dried coal fed to the first-stage carbonization apparatus 20 is sub-jected to a first-stage carbonization at a temperature at which the coal will generate a major proportion of moisture and a minor proportion of tar. The dried coal which has passed the first stage carbonization (hereinafter referred to as first-stage carbonized coal) is withdrawn from the first-stage carbonization apparatus 20 and fed to a second-stage carbonization apparatus 30~ A moisture-rich gas mixture C is withdrawn from the first-stage carbonization apparatus 20 through an exit pipe 21 and then, for example, fed to a combustion furnace 40 for generating a heating medium fed to the first-stage carbonization apparatus 20 and the second-stage carbonization apparatus 30. The second-stage carbonization apparatus 30 is connected in series to the first-stage carbonization apparatus 20.
Here, the first-stage carbonization apparatus 20 and the second-stage carbonization apparatus 30 are each, for `:',' ' . ':
: . :
:. ;. - . -:
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example, an indirect heating rotary drum. The first-stage carbonized coal fed to the second-stage carbonization apparatus 30 is subjected to the second-stage carbonization at a temperature at which the coal generates a minor pro-S portion of moisture and a major proportion of tar. Thefirst-stage carbonization coal which has passed the second-stage carbonization (hereinafter referred to as second-stage carbonized coal) is withdrawn from the second-stage carbonization apparatus 30 and fed to a tar applicator 50.
A tar-rich gas mixture D is withdrawn from the second-stage carbonization apparatus 30 through an exit pipe 31 and fed to the tar applicator 50. The second-stage carbonized coal is cooled to a temperature of 50C or lower in the tar applicator 50, and brought into direct contact with the gas mixture D. In this way, the tar is adhered selectively and with certainty to the second-stage carbonized coal, whereby this coal is converted into improved coal E. This coal E
is withdrawn from the tar applicator 50 and then transfer red to, for example, a coal yard for storage. A gas F
which is excess gas not consumed in the tar ~pplicator 50 is withdrawn from the applicator 50 through an exit pipe 51 and then fed to, for example, a combustion furnace 40, where it is burnt.
Figs. 2 to 5 are diagrams each showing the relationship between the carbonization temperature and the amount of the tar, moisture or decomposition gas generated from low-rank coal during carbonization having properties shown in Table 1. In these figures, curve I is concerned with tar, curve II moisture, and curve III decomposition gas. They show that in each of low-rank coals Al to A~, generation of the moisture during thermal cracking begins at a carbonization temperature of about 200C and almost all of this moisture is generated before the carbon-ization temperature reaches about 300C. On the other hand, generation of the tar begins at a carbonization temperature of about 300C, and when the carbonization ,: ,. :.. . :
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temperature exceeds 450C, the amount of tar generation is decreased because the tar itself is decomposed.
Table 1 PROPERTIES OF LOW-RANK COALS Al TO A4 Properties Low-rank Low-rank Low-rank Low-rank coal Al coal A2 coal A3 coal A4 Moisture total moisture (%)25.3 30.3 25.4 31.6 inherent moisture (%) 16.0 13.2 18.2 18.9 Technical analysis (dry basis) volatile matter (~) 47.6 45.4 38.0 46.6 fixed carbon (%) 45.6 48.4 53.3 45.5 ash (~) 6.8 6.2 8.7 7.9 Elementary analysis (Daf) C (~) 69.1 69.9 70.7 69.3 H (9~) 5.5 4.9 4.7 5.2 N (%) 1.0 1.1 1.3 1.1 S (%) 0.5 0.5 0.7 0.4 O (%) 23.9 23.6 22.7 24.0 Calorific value (wet basis) 4,980 4,270 4,850 4,260 (kcal/kg) Low-tempe~ature oxidation 4.3 3.4 3.1 5.6 rate (mol/g-min) Fuel ratio (-) 0.96 1.07 1.4 0.98 Bulk density (kg/m3) 710 770 760 740 Grindability (HGI) (-) ! 75 Therefore, when only the gas mixture generated from low-rank coal at a carbonization temperature of 300C or above, preferably at a carbonization temperature of 300 to 450C
is separated and brought into contact with the carbonized coal, the amount of moisture which is adhered to the carbonized coal during the selective adherence of the tar to the carbonized coal can be decreased in spite of the low temperature of the carbonized coal, because the absolute - -. , . : ~ . . .
- .
;,, ~2~444 amount of moisture in the gas mixture is low. In this case, the minimum carbonization time is a time during which tar can be generated in an amount necessary for adherence to the second-stage carbonized coal (at least 3~, based on dry coal feed) and residual oxygen in the second-stage carbonized coal can be decreased to 15% (elementary analysis) or below, while the maximum carbonization time is 8 hours. When this time exceeds 8 hours, a disadvantage exists in that the second-stage carbonized coal has an increased grindability and easily forms pulverized coal.
For example, when low-rank coal A4 is used, the carbon-ization time under conditions oE a constant carbonization temperature of 400C is 4 to 8 hours.
Taking the above results into consideration, the up-grading of low-rank coaLs Al to A3 was carried out.
In Fig. 1, the carbonization temperature in the first-step carbonization apparatus 20 was adjusted to 280C, and that in the second-stage carbonization apparatus 30 was adjusted to 400C. The conditions of the atmosphere in each carbon--ization were as follows. The atmosphere was an inert gas,and its pressure was normal. The results are shown in Table 1. The adherence of the tar to the second-stage carbonized coal was performed with certainty and at the same time the amount of the moisture adhered thereto was markedly decreased.
Table 2 Process according to Low-rank Japanese Patent Laid- This example 30coal Open No. 32894/1985 Tar (~) Moisture (%) Tar (~) Moisture (%) Al 7.8 10.4 7.5 4.7
Process for improving low-rank coal and apparatus therefo_ This invention relates to a process and apparatus for improving low-rank coal. More particularly the invention relates to a process and apparatus for improving low-rank coal which is suitable for improving low-rank coal into coal having a low adherent water content and excellent moisture resistance.
Known techniques for improving low-rank coal, such as sub-bituminous coal or lignite, into coal of excellent moisture resistance include, for example, a process described in Japanese Patent Publication No. 115965/1982.
Such a process comprises quickly heating low-rank coal to a final heating temperature of 300 to 500C at a rate of temperature rise of at least 100C/min and quickly cooling the coal to a temperature of 250C or below at a rate of temperature fall of 50C/min or greater to thereby block pores in the coal by solidifying, without allowing evaporation. In this process a liquid tae-like material exudes to the surface of the coal during its thermal cracking, thus decreasing the specific surface area of the coal to thereby decrease the rnoisture absorption of the coal.
However, the tar obtained by such a heat-treatment of coal contains as much as 90~ low-boiling substances (b.p._ 200C). As a result, the gasification rate of the tar is so high that it is extremely difficult to solidify . ,, ,~, . ':.~ ' ~: '' '` ;
.,. :, , . -. .
': ~ .,'': '' lZ6~49~
- the tar exuding to the surface of the coal before its gasification. Therefore, there is a problem in decreasing the moisture absorption of coal, that is, improving it into coal of excellent moisture resistance.
It is an object of this invention ~o provide a process and an apparatus for improving low-rank coal into coal having a low adherent moisture content and excellent moisture resistance by bringing a tar-rich gas mixture selectively separated from a gas mixture produced from the low-rank coal during a step of carbonizing it into contact with low-rank coal which has passed the carbonization step and thereby adhering the tar to the low-rank coal.
In accordance with an aspect of the invention, there is provided a process for improving low-rank coal, comprising a step of first-stage carbonizing said low-rank coal at a temperature at which it generates a moisture-rich gas mix-ture, a step of second-stage carbonizing said low-rank coal, which has passed the first-stage carbonization step, at a temperature at which it generates a tar-rich gas mixture, a step of cooling said low-rank coal which has passed the second-stage carbonization step, and a step of bringing the tar-rich gas mixture into contact with said cooled low-rank coal to thereby adhere the tar to said cooled low-rank coal.
In accordance with another aspect of the invention there is provided an apparatus for improving low-rank coal, comprising means for first-stage carbonizing said low-rank coal at a temperature at which it generates a moisture-rich gas mixture, means for second-stage carbonizing said low-rank coal, which has passed the first-stage carbonization, at a temperature at which it generates a tar-rich gas mixture, means for cooling said low-rank coal which has passed the second-stage carbonization, and means for bringing the tar-rich gas mixture into contact with said cooled low-rank coal to thereby adhere the tar to said cooled low-rank coal.
. ;
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- 2a -Thus, according to this invention, the tar-rich gas mixture selectively separated from the gas produced from low-rank coal during its carbonization step is brought into contact with low-rank coal which has passed the carbonization step, whereby the tar can be adhered to said low-rank coal.
- :
, :~: '- ;' ' :
... :'~ '' - : ~;
~268~
The present invention will be described in detail hereinbelow with the aid of the accompanying drawings, in which:
Fig. 1 is a flow chart for practicing the present invention and illustrating an example of a process for improving low-rank coal according to this invention;
Figs. 2 to 5 are diagrams of the relationship between the carbonization temperature and the amount of the tar, moisture or decomposition gas produced from low-rank coal during its carbonization;
Fig. 6 is a schematic diagram of a moving-bed carbonization apparatus which is another example of this invention; and Fig. 7 is a diagram showing the distribution of coal temperature within the moving-bed carbonization apparatus.
When low-rank coal such as sub-bit~ninous coal or lignite is carbonized at a temperature of 250 to 450C, hydrophobic coal having a high calorific value can be obtained. In order to highly improve such low-rank coal, it is effective to adhere a tar produced from the low-rank coal during its carbonization step to low-rank coal which has passed the carbonization step (hereinafter referred to as carbonized coal). The inventors of this invention previously proposed a process comprising bringing tar produced from low-rank coal during its carbonization step a~d not separated from entrained moisture into direct contact with carbonized and cooled coal to thereby selectively adhere the tar to the coal tsee Japanese Patent Laid-Open No. 32894/1985~.
However, this process has a disadvantage that when the temperature of the carbonized and cooled coal is low, almost all of the moisture and the tar are adhered to the carbonized coal, which increases the content of adherent moisture. The present invention provides a process and apparatus which decreases the amount of the moisture adhering to the carbonized coal.
. .
. . . .
: :~ . . ..
.... ..
,. .. .. , :
:- : ,-. . .:
.-~.: : -A considerable temperature difference existsbetween the carbonization temperature at which moisture begins to be generated from low-rank coal during its carbonization (hereinaEter referred to as moisture S generation-initiating carbonization temperature) and that at which tar begins to be generated from low-rank coal during its carbonization (hereinafter referred to as a tar generation-initiating carbonization temperature).
An example of this invention will now be described with reference to Figs. 1 to 5.
Referring to Fig. 1, low-rank coal A is fed to a dryer 10, such as a direct heating rotary drum, where it is dewatered and dried at a temperature of 80 to 150C.
The low-rank coal which has passed the drying step (here-inafter referred to as dried coal) is withdrawn from thedryer 10 and fed to a first-stage carbonization apparatus 20. Moisture B generated from low-rank coal A during the drying step is withdrawn from the dryer 10 through an exit pipe 11 and discharged from the system. The dried coal fed to the first-stage carbonization apparatus 20 is sub-jected to a first-stage carbonization at a temperature at which the coal will generate a major proportion of moisture and a minor proportion of tar. The dried coal which has passed the first stage carbonization (hereinafter referred to as first-stage carbonized coal) is withdrawn from the first-stage carbonization apparatus 20 and fed to a second-stage carbonization apparatus 30~ A moisture-rich gas mixture C is withdrawn from the first-stage carbonization apparatus 20 through an exit pipe 21 and then, for example, fed to a combustion furnace 40 for generating a heating medium fed to the first-stage carbonization apparatus 20 and the second-stage carbonization apparatus 30. The second-stage carbonization apparatus 30 is connected in series to the first-stage carbonization apparatus 20.
Here, the first-stage carbonization apparatus 20 and the second-stage carbonization apparatus 30 are each, for `:',' ' . ':
: . :
:. ;. - . -:
~2~j8~
example, an indirect heating rotary drum. The first-stage carbonized coal fed to the second-stage carbonization apparatus 30 is subjected to the second-stage carbonization at a temperature at which the coal generates a minor pro-S portion of moisture and a major proportion of tar. Thefirst-stage carbonization coal which has passed the second-stage carbonization (hereinafter referred to as second-stage carbonized coal) is withdrawn from the second-stage carbonization apparatus 30 and fed to a tar applicator 50.
A tar-rich gas mixture D is withdrawn from the second-stage carbonization apparatus 30 through an exit pipe 31 and fed to the tar applicator 50. The second-stage carbonized coal is cooled to a temperature of 50C or lower in the tar applicator 50, and brought into direct contact with the gas mixture D. In this way, the tar is adhered selectively and with certainty to the second-stage carbonized coal, whereby this coal is converted into improved coal E. This coal E
is withdrawn from the tar applicator 50 and then transfer red to, for example, a coal yard for storage. A gas F
which is excess gas not consumed in the tar ~pplicator 50 is withdrawn from the applicator 50 through an exit pipe 51 and then fed to, for example, a combustion furnace 40, where it is burnt.
Figs. 2 to 5 are diagrams each showing the relationship between the carbonization temperature and the amount of the tar, moisture or decomposition gas generated from low-rank coal during carbonization having properties shown in Table 1. In these figures, curve I is concerned with tar, curve II moisture, and curve III decomposition gas. They show that in each of low-rank coals Al to A~, generation of the moisture during thermal cracking begins at a carbonization temperature of about 200C and almost all of this moisture is generated before the carbon-ization temperature reaches about 300C. On the other hand, generation of the tar begins at a carbonization temperature of about 300C, and when the carbonization ,: ,. :.. . :
,~ , ' ,.... . .
~268gL~
temperature exceeds 450C, the amount of tar generation is decreased because the tar itself is decomposed.
Table 1 PROPERTIES OF LOW-RANK COALS Al TO A4 Properties Low-rank Low-rank Low-rank Low-rank coal Al coal A2 coal A3 coal A4 Moisture total moisture (%)25.3 30.3 25.4 31.6 inherent moisture (%) 16.0 13.2 18.2 18.9 Technical analysis (dry basis) volatile matter (~) 47.6 45.4 38.0 46.6 fixed carbon (%) 45.6 48.4 53.3 45.5 ash (~) 6.8 6.2 8.7 7.9 Elementary analysis (Daf) C (~) 69.1 69.9 70.7 69.3 H (9~) 5.5 4.9 4.7 5.2 N (%) 1.0 1.1 1.3 1.1 S (%) 0.5 0.5 0.7 0.4 O (%) 23.9 23.6 22.7 24.0 Calorific value (wet basis) 4,980 4,270 4,850 4,260 (kcal/kg) Low-tempe~ature oxidation 4.3 3.4 3.1 5.6 rate (mol/g-min) Fuel ratio (-) 0.96 1.07 1.4 0.98 Bulk density (kg/m3) 710 770 760 740 Grindability (HGI) (-) ! 75 Therefore, when only the gas mixture generated from low-rank coal at a carbonization temperature of 300C or above, preferably at a carbonization temperature of 300 to 450C
is separated and brought into contact with the carbonized coal, the amount of moisture which is adhered to the carbonized coal during the selective adherence of the tar to the carbonized coal can be decreased in spite of the low temperature of the carbonized coal, because the absolute - -. , . : ~ . . .
- .
;,, ~2~444 amount of moisture in the gas mixture is low. In this case, the minimum carbonization time is a time during which tar can be generated in an amount necessary for adherence to the second-stage carbonized coal (at least 3~, based on dry coal feed) and residual oxygen in the second-stage carbonized coal can be decreased to 15% (elementary analysis) or below, while the maximum carbonization time is 8 hours. When this time exceeds 8 hours, a disadvantage exists in that the second-stage carbonized coal has an increased grindability and easily forms pulverized coal.
For example, when low-rank coal A4 is used, the carbon-ization time under conditions oE a constant carbonization temperature of 400C is 4 to 8 hours.
Taking the above results into consideration, the up-grading of low-rank coaLs Al to A3 was carried out.
In Fig. 1, the carbonization temperature in the first-step carbonization apparatus 20 was adjusted to 280C, and that in the second-stage carbonization apparatus 30 was adjusted to 400C. The conditions of the atmosphere in each carbon--ization were as follows. The atmosphere was an inert gas,and its pressure was normal. The results are shown in Table 1. The adherence of the tar to the second-stage carbonized coal was performed with certainty and at the same time the amount of the moisture adhered thereto was markedly decreased.
Table 2 Process according to Low-rank Japanese Patent Laid- This example 30coal Open No. 32894/1985 Tar (~) Moisture (%) Tar (~) Moisture (%) Al 7.8 10.4 7.5 4.7
2 ~ 9.4 4.5 2.8
3 I - 6.6 4.2 ¦ 3.4 In this example, the tar generated during the .
:
61~4~
carbonization of low-rank coal was adhered to the carbon-ized coal with certainty, so that the low-rank coal was improved into coal of excellent moisture resistance. At the same time, because of a small absolute content of moisture in the gas mixture in direct contact with the carbonized coal, the amount of moisture adhered to the carbonized coal was markedly decreased even when the temperature o~ the cooled carbonized coal was low.
Although the carbonization apparatus in the above example is comprised of a first-stage and a second-stage carbonization apparatus which are arranged separately, a single carbonization apparatus, which is not separated can also be used.
In this case, the temperature of a carbonization atmosphere in the carbonization apparatus, or the temper-ature of the coal being carbonized, is detected and monitored. When the temperature is 280C or below, the generated gas mixture is withdrawn from the carbonization apparatus and burnt in a combustion furnace. The temper-ature is then controlled to 300C or above, preferably 300 to 450C, and the gas mixture generated under this con-dition is withdrawn from the carbonization apparatus and fed to a tar applicator. In the above case, one carbon-ization apparatus suffices or the process, so that the equipment cost can be ~urther reduced as compared with that in the first described example.
It is also possible to integrate a dryer and a carbonization apparatus into one heat treatment apparatus.
In this case, it is suitable that the heat treatment temperature in this heat treatment apparatus is controlled so as to increase stepwise to 80 - 150C, 280C or below, and 300C, preferably 300 - 450C, and the gas generated during carbonization at each of these temperatures is treated in the same manner as in the above example.
Figs. 6 and 7 show another example of this invention, which is different from the above examples :: ~ ~ .. .. .
.. . .
' - ~' ', , , -~ -' , ' ~Z6~4~
in that the carbonization apparatus in the above examples are replaced with one carbonization apparatus, and this carbonization apparatus comprises a moving-bed carbon-ization apparatus.
In Fig. 6, dry coal G from a dryer (not shown) is fed through a feed inlet 61 to the top of a moving-bed carbonization apparatus 60. The dry coal G is heated with a heating medium passing through a heating tube 62 during its downward movement through the carbonization apparatus 60. Carbonized coal H is discharged from a discharge exit 63 on the bottom and fed to a tar applicator (not shown).
The temperature of the coal in the moving-bed carbonization apparatus 60 varies, as shown in Fig. 7, along the vertical direction. Therefore/ the moving-bed carbonization 1~ apparatus 60 is provided, in its inside, with a means by which an empty space 64 is formed against the coal moving through the carbonization apparatus 60 in a position cor-responding to a temperature at which the coal can generate a minor proportion of moisture and a major proportion oE
tar. In this case, the position of space 64 corresponds to a coal temperature of 300C. One end of a gas withdrawl pipe 66 is open to the empty space 64, and the other end is open to the tar applicator. Further, one end of a gas withdrawl pipe 67 is connected to the top of the moving-bed carbonization apparatus 60, and the other end is connected to, Eor example, a combustion furnace (not shown) for generating a heating medium fed to the heating tube 62.
In Fig. 6, the moisture-rich gas mixture C
generated in the moving-bed carbonization apparatus 60 is withdrawn from the apparatus 60 through the gas withdrawl pipe 67 and fed to the combustion furnace, where it is burnt. The tar-rich gas mixture D generated in the part below the empty space 6~ in the -carbonization apparatus 60 is collected in the empty space 64, and the collected gas mixture D is withdrawn through the gas withdrawl pipe 66 and fed to the tar applicator. In this applicator, the carbonized coal H is converted into improved coal by the same procedures as in the first example.
. ~ :
- . '
:
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carbonization of low-rank coal was adhered to the carbon-ized coal with certainty, so that the low-rank coal was improved into coal of excellent moisture resistance. At the same time, because of a small absolute content of moisture in the gas mixture in direct contact with the carbonized coal, the amount of moisture adhered to the carbonized coal was markedly decreased even when the temperature o~ the cooled carbonized coal was low.
Although the carbonization apparatus in the above example is comprised of a first-stage and a second-stage carbonization apparatus which are arranged separately, a single carbonization apparatus, which is not separated can also be used.
In this case, the temperature of a carbonization atmosphere in the carbonization apparatus, or the temper-ature of the coal being carbonized, is detected and monitored. When the temperature is 280C or below, the generated gas mixture is withdrawn from the carbonization apparatus and burnt in a combustion furnace. The temper-ature is then controlled to 300C or above, preferably 300 to 450C, and the gas mixture generated under this con-dition is withdrawn from the carbonization apparatus and fed to a tar applicator. In the above case, one carbon-ization apparatus suffices or the process, so that the equipment cost can be ~urther reduced as compared with that in the first described example.
It is also possible to integrate a dryer and a carbonization apparatus into one heat treatment apparatus.
In this case, it is suitable that the heat treatment temperature in this heat treatment apparatus is controlled so as to increase stepwise to 80 - 150C, 280C or below, and 300C, preferably 300 - 450C, and the gas generated during carbonization at each of these temperatures is treated in the same manner as in the above example.
Figs. 6 and 7 show another example of this invention, which is different from the above examples :: ~ ~ .. .. .
.. . .
' - ~' ', , , -~ -' , ' ~Z6~4~
in that the carbonization apparatus in the above examples are replaced with one carbonization apparatus, and this carbonization apparatus comprises a moving-bed carbon-ization apparatus.
In Fig. 6, dry coal G from a dryer (not shown) is fed through a feed inlet 61 to the top of a moving-bed carbonization apparatus 60. The dry coal G is heated with a heating medium passing through a heating tube 62 during its downward movement through the carbonization apparatus 60. Carbonized coal H is discharged from a discharge exit 63 on the bottom and fed to a tar applicator (not shown).
The temperature of the coal in the moving-bed carbonization apparatus 60 varies, as shown in Fig. 7, along the vertical direction. Therefore/ the moving-bed carbonization 1~ apparatus 60 is provided, in its inside, with a means by which an empty space 64 is formed against the coal moving through the carbonization apparatus 60 in a position cor-responding to a temperature at which the coal can generate a minor proportion of moisture and a major proportion oE
tar. In this case, the position of space 64 corresponds to a coal temperature of 300C. One end of a gas withdrawl pipe 66 is open to the empty space 64, and the other end is open to the tar applicator. Further, one end of a gas withdrawl pipe 67 is connected to the top of the moving-bed carbonization apparatus 60, and the other end is connected to, Eor example, a combustion furnace (not shown) for generating a heating medium fed to the heating tube 62.
In Fig. 6, the moisture-rich gas mixture C
generated in the moving-bed carbonization apparatus 60 is withdrawn from the apparatus 60 through the gas withdrawl pipe 67 and fed to the combustion furnace, where it is burnt. The tar-rich gas mixture D generated in the part below the empty space 6~ in the -carbonization apparatus 60 is collected in the empty space 64, and the collected gas mixture D is withdrawn through the gas withdrawl pipe 66 and fed to the tar applicator. In this applicator, the carbonized coal H is converted into improved coal by the same procedures as in the first example.
. ~ :
- . '
Claims (6)
1. A process for improving low-rank coal, comprising a step of first-stage carbonizing said low-rank coal at a temperature at which it generates a moisture-rich gas mixture, a step of second-stage carbonizing said low-rank coal, which has passed the first-stage carbonization step, at a temperature at which it generates a tar-rich gas mixture, a step of cooling said low-rank coal which has passed the second-stage carbonization step, and a step of bringing the tar-rich gas mixture into contact with said cooled low-rank coal to thereby adhere the tar to said cooled low-rank coal.
2. A process according to claim 1, wherein said low-rank coal is carbonized in the first-stage carbonization step at a temperature not lower then 280°C, and the low-rank coal which has passed the first-stage carbonization step is carbonized in the second-stage carbonization step at a temperature not lower than 300°C.
3. A process according to Claim 1 wherein the temperature in the second-stage carbonizing step is 300-450°C.
4. An apparatus for improving low-rank coal, comprising means for first-stage carbonizing said low-rank coal at a temperature at which it generates a moisture-rich gas mixture, means for second-stage carbonizing said low-rank coal, which has passed the first-stage carbonization, at a temperature at which it generates a tar-rich gas mixture, means for cooling said low-rank coal which has passed the second-stage carboniz-ation, and means for bringing the tar-rich gas mixture into contact with said cooled low-rank coal to thereby adhere the tar to said cooled low-rank coal.
5. An apparatus according to Claim 4, wherein said means for the first-stage carbonizing of the low-rank coal comprises an indirect heating rotary drum, and said means for the second-stage carbonizing of said low-rank coal which has passed the first stage carbonization comprises an indirect heating rotary drum.
6. An apparatus according to claim 4, wherein said means for the first-stage carbonizing of the low-rank coal and said means for the second-stage carbonizing of the low-rank coal which has passed the first-stage carbonization comprise one moving-bed carbonization apparatus, said moving-bed carbonization apparatus being provided therein with means by which an empty space is formed against the coal moving through said apparatus in a position corresponding to a temperature at which the coal generates a tar-rich gas mixture, and a gas withdrawal pipe for withdrawing said gas mixture from said empty space and feeding it to a means for bringing it into contact with said low-rank coal which has passed the carbonization steps and been cooled, to thereby adhere tar from said tar-rich gas mixture to said low-rank coal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10808/1985 | 1985-01-25 | ||
| JP1080885A JPS61171796A (en) | 1985-01-25 | 1985-01-25 | Method for improving quality of low-grade coal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1268444A true CA1268444A (en) | 1990-05-01 |
Family
ID=11760641
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000500302A Expired CA1268444A (en) | 1985-01-25 | 1986-01-24 | Process for improving low-rank coal and apparatus therefor |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS61171796A (en) |
| AU (1) | AU577176B2 (en) |
| CA (1) | CA1268444A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0351478A1 (en) * | 1988-07-19 | 1990-01-24 | Victory | Hand operated chain block |
| JP2010155913A (en) * | 2008-12-26 | 2010-07-15 | Ono Kensetsu:Kk | Method for producing incomplete combustion gas of arbores, incomplete combustion gas, wood vinegar, snow thawing agent, method for producing metal formate mixture, and metal formate mixture |
| JP6068857B2 (en) * | 2012-07-30 | 2017-01-25 | 株式会社キトー | Chain block |
| JP6130114B2 (en) * | 2012-09-14 | 2017-05-17 | 九州電力株式会社 | Power generation system |
| CN107033963A (en) * | 2017-05-31 | 2017-08-11 | 河南龙成煤高效技术应用有限公司 | A kind of pyrolytic process of coal device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5738891A (en) * | 1980-08-18 | 1982-03-03 | Idemitsu Kosan Co Ltd | Selective agglomeration of coal particle |
-
1985
- 1985-01-25 JP JP1080885A patent/JPS61171796A/en active Pending
-
1986
- 1986-01-22 AU AU52613/86A patent/AU577176B2/en not_active Ceased
- 1986-01-24 CA CA000500302A patent/CA1268444A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU577176B2 (en) | 1988-09-15 |
| JPS61171796A (en) | 1986-08-02 |
| AU5261386A (en) | 1986-07-31 |
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