CA1271151A - Production of hydrocarbon oils by vacuum pyrolysis of scrap tires - Google Patents
Production of hydrocarbon oils by vacuum pyrolysis of scrap tiresInfo
- Publication number
- CA1271151A CA1271151A CA000509162A CA509162A CA1271151A CA 1271151 A CA1271151 A CA 1271151A CA 000509162 A CA000509162 A CA 000509162A CA 509162 A CA509162 A CA 509162A CA 1271151 A CA1271151 A CA 1271151A
- Authority
- CA
- Canada
- Prior art keywords
- reactor
- heat exchanger
- temperature
- gaseous hydrocarbons
- pyrolysis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
"PRODUCTION OF HYDROCARBON OILS BY
VACUUM PYROLYSIS OF SCRAP TIRES"
Abstract of the Disclosure A process for the treatment of used rubber tires by vacuum pyrolysis in a reactor to produce liquid and gaseous hydrocarbons and a solid carbona-ceous material is disclosed. According to the inven-tion, the pyrolysis of the tires is carried out at a temperature in the range of about 360°C to about 415°C, under a sub-atmospheric pressure of less than about 35 mm Hg and such that gases and vapors produced in the reactor have a residence time of the order of a few seconds. The process according to the invention enables one to increase the yield of the liquid hydro-carbons and lower the yields of the gaseous hydrocarbons and solid carbonaceous material, and to thereby produce hydrocarbon oils in substantially maximum yield. These hydrocarbon oils have a high calorific value and are thus suitable for use as heating fuel.
VACUUM PYROLYSIS OF SCRAP TIRES"
Abstract of the Disclosure A process for the treatment of used rubber tires by vacuum pyrolysis in a reactor to produce liquid and gaseous hydrocarbons and a solid carbona-ceous material is disclosed. According to the inven-tion, the pyrolysis of the tires is carried out at a temperature in the range of about 360°C to about 415°C, under a sub-atmospheric pressure of less than about 35 mm Hg and such that gases and vapors produced in the reactor have a residence time of the order of a few seconds. The process according to the invention enables one to increase the yield of the liquid hydro-carbons and lower the yields of the gaseous hydrocarbons and solid carbonaceous material, and to thereby produce hydrocarbon oils in substantially maximum yield. These hydrocarbon oils have a high calorific value and are thus suitable for use as heating fuel.
Description
~7~L151 BACKGROUND OF THE INVENTION
The present invention relates to a process for the treatment of used rubber tires by vacuum pyrolysis to produce liquid and gaseous hydrocarbons and a solid carbonaceous material.
The accumulation of large quantities of scrap tires has become a major environmental problem. Because of their resistance to biodegradation, used automobile tires provide a favourable environment for vermin, rodents and fire. Environmental regulations, on the other hand, prohibit the disposal of such waste materials - by burning outdoors or by burial underground.
One possible solution to the above problem is to convert the tires into fuels and other useful hydro-carbon products, for instance by thermal decomposition.
In order to avoid side reactions and cross-reactions among product species when heating the tires under atmos-~: :
pheric or superatmospheric pressure, which results in ~' a very inefficient conversion process, U.S. Patent No.
4,235,676 has proposed to conduct the pyrolysis of rubber tires under sub-atmospheric pressure. According to this patent, the vacuum pyrolysis of tires is effected by moving a mass of shredded tires through an elongated tubular mem-ber maintained at a temperature between about 400~ and ,::
~ 800C, in the absence of air and/or oxygen, with the material being turned or stirred as it passes through . ~ :
the tubular member, and withdrawing the gases and vapors produced by means of a vacuum of from about 4 inches to about 6 inches of mercury (i.e. an absolute pressure of from about 608 mm Hg to about 658 mm Hg). The process conditions, however, are such as to promote the forma-~1.;;~7~151 tion of gaseous hydrocarbons to the detriment of-the more highly desirable hydrocarbon oils.
SVMMARY OF THE INVEN'rION
It is therefore an object of the present invention to carry out the pyrolysis of used rubber tires under conditions to promote the formation of liquid hydroearbons and to thereby yield higher amounts of hydrocarbon oils.
In accordance with the invention, there is thus provided a process for the treatment of used rubber tires by vacuum pyrolysis in a reactor to pro-duce liquid and gaseous hydrocarbons and a solid carbona-~ ceous material, wherein the pyrolysis of the tires is : carried out at a temperature in the range of about 360C
to about 415C, under a sub-atmospheric pressure of less than about 35 mm Hg and such that gases and vapors pro-duced in the reactor have a residence time of the order of a few seconds, whereby to increase the yield of the ; ~ liquid hydrocarbons~and lower the yields of the gaseous -: : 20 hydrocarbons and solid carbonaeeous material.
~. .
` :~ ; It has been unexpeetedly found, according to the invention, that by seleeting a pyrolysis tempera-~; ~ ture of about 360C to about 415C, preferably of about 380C to about 400C, a sub-atmospheric pressure of less .
than about 35 mm Hg, preferably of less than about ; 30 mm Hg, and a residence time of the gases and vapors : in the reactor of a few seconds, preferably 1-3 sec., and eondueting the process with sueh seleeted parameters, the yield of the highly desirable liquid hydrocarbons is signifieantly inereased while the yields of the less ;~ : desirable gaseous hydrocarbons and solid carbonaceous ,: ~
;
.
: ;- - :
.
- .
711S~
material are lowered, thereby enabling hydrocarbon oils to be obtained in substantially maximum yield. Indeed, it has been observed that if the tires are treated at a temperature above 415C, there is a gasification of the residual solid carbonaceous material, producing more gaseous hydrocarbons without formation of any further liquid hydrocarbons. On the other hand,operat-ing under a sub-atmosphexic pressure greater than 35 mm Hg has been found to promote the formation of gaseous hydrocarbons to the detriment of the liquid hydrocarbons; a too long residence time of the gases and vapors in the reactor, i.e. exceeding a few seconds, , ~
- also has the same detrimental effect.
The used rubber tires, prior to undergoing pyrolysis, are preferably shredded into cuttings. Such tire cuttings may have a mesh size of about 5-15 mm, for example.
-; According to a preferred embodiment of the invention, the reactor used for carrying the pyrolysis is ;~20 a multi-tray reactor having a plurality of spaced-apart heated trays arranged above one another and each adapted to receive a bed of the tire cuttings for subjecting :. -i~:
same to the pyrolysis. The trays are heated at tempera-~ tures to provide a vertical temperature gradient between ;j25 uppermost and lowermost trays with the lowermost tray being heated at a temperature higher than the uppermost ~-tray. For example, the uppermost and lowermost trays may be heated at about 250C and about 500C, respect-ively: it should be understood, however, that the bed Of tire cuttings even lf heated by means of a tray main-tained at a temperature of about 500C is not allowed .
~L2~ 5~
to reach a temperature exceeding about 415C and this may be achieved by controlling the residence time of the tire cuttings on such a tray.
Such a multi-tray reactor is advantageously provided with a plurality of discharge outlets each associated with a respective tray for discharging gaseous - hydrocarbons and condensable hydrocarbon vapors generated in the reactor. These gaseous hydrocarbons and condens-able hydrocarbon vapors are withdrawn from the reactor through the discharge outlets and passed through heat exchanger means for condensing the condensable hydrocarbon vapors to thereby obtain the liquid hydrocarbons. To this end, the discharge outlets are connected via the heat exchanger means to vacuum means for maintaining the sub-atmospheric pressure in the reactor and causing the ,~
gaseous hydrocarbons and condensable hydrocarbon vapors to flow out of the reactor through the discharge outlets.
, Preferably, the heat exchanger means include primary and secondary heat exchanger means, the primary heat exchanger means comprising a plurality of heat exchanger elements each connected to a respective dischar-ge`outlet. The heat exchanger elements are maintained at temperatures to provide a vertical temperature gra-dlent between uppermost and lowermost heat exchanger ~ 25 elements with the lowermost heat exchanger element being ;~ mdintained at a temperature higher than the uppermost ~ -:
heat exchanger element. For example, the uppermost and lowermost heat exchanger elements may be maintained at about 10C and about 40C, respectively. The secondary heat exchanger means, on the other hand, may comprise a plurality o~ condensation traps in fluid flow communi-.
:: _ 5 , ,. :, ~ ~: , . - . . . .
, - . - - - , Li5~L
cation with one another. Thus, the gaseous hydrocarbons and condensable hydrocarbon vapors after having passed through the prlmary heat exchanger means are passed into the condensable traps from one to another. For example, the gaseous hydrocarbons and condensable hydrocarbon vapors may be first passed into a condensation trap main-tained at a temperature of about -20C and then into the other condensation traps which are maintained at a tempe-- rature of about -80C.
; 10 As indicated above, the process according to ~` the invention enables used rubber tires to be converted into high amounts of liquid hydrocarbons. Typically, about 60 weight ~ liquid hydrocarbons, about 38 weight solid carbonaceous material and about 2 weight ~ gaseous hydrocarbons can be produced from used rubber tires by , ~ ~ the~process of the invention. The liquid hydrocarbons - ~ produced in accordance with the invention have a calorific va~lue of about 10,200 kcal kg 1 and are thus suitable for ; use as heatlng fuel.
BRIEF DESCRIPTION OF THE DRAWINGS
~: : :
Further features and advantages of the inven-tion will become more readily apparent from the following descrlptlon of preferred embodiments thereof as illustra-ted by way of example in the accompanying drawings, in ~ which I Fig. 1 is schematic illustration of an apparatus for carrying a process accordlng to the invention' Fig. 2 is a plot of the product yield as a ~ : :
function of temperature; and Fig. 3 is a plot of the yield of liquid hydro-carbons as a function of pressure.
:
~ 6 -~L2'7~ 3l51 DESCRIPTION OF PREFERRED EMBODIMENTS
, ., . _ _ - Referring first to Fig. 1, there is illustrated an apparatus for carrying out the vacuum pyrolysis o~ used rubber tires in the form of cuttings, comprising a multi-tray reactor 10 having a plurality o~ spaced-apart heated _ .
trays 12 arranged abo~e one another and each adapted to receive a bed of tire cuttings charged into the reactor _ via the hopper 14 and transported from an upper to a lower tray by conventional means (not illustrated,) for subjecting the tire cuttings to pyrolysis. The trays 12 are heated at temperatures to provide a vertical temperature gradient between the uppermost and lowermost trays with the lowermost tray being heated at a temperature higher than the uppermost tray. Typically, the uppermost and lowermost trays are heated at about 250C and about 500C, respectively. The heating of the trays 12 and the residence time of the tire cuttings thereon are such that the tire cuttings when ~-~ reaching the lower portion of the reactor (i.e. the two ..~
lowermost trays) are treated at a temperature of about 360C
~ .
to about 415C and that the temperature of the tire cuttings does not exceed about 415C.
The reactor 12 is provided with a plurallty of discharge outlets 16 each associated with a respective ; tray~12 for discharging the gaseous hydrocarbons and condensable hydrocarbon vapors generated in the reactor.
.::
~ ~ The discharge outlets 16 are connected via primary and ..
secondary heat exchangers 18 and 20 to a vacuum pump 22 for maintaining sub-atmospheric pressure in the reactor 12 and causing the gaseous hydrocarbons and condensable hydrocarbon vapors to flow out of the reactor through the ~; ~ discharge outlets. A sub-atmospheric pressure of less than about 35 mm Hg is maintained in the reactor 12 by : ' -.:
~: . . .
.
.
~7~
means of a vacuum control device 24 connected to the vacuum line 26 and adapted to set a predetermined sub-atmospheric pressure. The vacuum line 26 which is pro-vided with a valve 28 is bifurcated into two lines, a first line 30 provided with a valve 32 and connected to a gas reservoir or tank 34 for storing the gaseous hydrocarbons produced in the reactor 12, and a second line 36 leading to the vacuum pump 22. A further line 38 provided with valves 40 and 42 interconnects the vacuum pump 22 and gas tank 34, the valve 42 being a vent valve.
The primary and secondary heat exchanger 18 and 20 through which the gaseous hydrocarbons and condensable hydrocarbon vapors are passed are adapted to condense the condensable hydrocarbon vapors to thereby obtain the desired liquid hydrocarbons. The primary heat exchanger 18 comprises a plurality of shell and tube ., heat exchanger elements 44 each connected to a respective discharge outlet 16. The heat exchanger elements 44 are .~ :
maintained at temperatures to provide a vertical tempera-ture gradient between the uppermost and lowermost heat exchanger elements wlth the lowermost heat exchanger element being maintained at a temperature higher than the uppermost heat exchanger element. Typically, the upper-~ ~ 25 most and lowermost heat exchanger elements are maintained '~ at about 10C and about 40C, respectively. About 70 -~ of the total condensable hydrocarbon vapors produced are condensed by means of the primary heat exchanger 18.
, The gaseous hydrocarbons and remaining conden-sahle hydrocarbon vapors leaving the heat exchanger " :: :
:. ~ : , ' S~
elements 44 are collected by means of the collecting conduit 46 and then passed through the secondary heat exchanger 20. The latter comprises a plurality of con-densation traps 48,50 in ~luid flow communication with one another. The first condensation trap 48 is advanta-geously maintained at a temperature of about -20C by means of a refrigerant coil52 in which an aqueous solution of ethylene glycol is circulated. The other condensa-; tion traps 50, on the other hand, are maintained at a temperature of about -80C by being immersed in acetone/C02 baths contained in thermos containers 54 supported on a wheeled vertically displaceable platform 56. A filter 58 comprising glass wool is provided for filtering the gaseous hydrocarbons from which have e~tracted any condensable hydrocarbon vapors, prior to , ~
- the gaseous hydrocarbons being sucked via lines 26,36 ~ .
through the vacuum~pump 22 and directed into the gas tank 34 via line 38.
The solid carbonaceous material which is pro-20 ~ duced in the reactor 12 as a result o~ the pyrolysis : ..
- of the tires is discharged via the bottom outlet 60 into a suitable container 62 placed underneath.
-At the start of the process, the gas tank 34 is first evacuated by closing the valves 28,40 and open-ing the valves 32,42 so that any air or other gas con-tained in the tank 34 is sucked via lines 30,36 through the vacuum pump 22 and vented to the atmosphere via line ,: : -~ 38 through the vent valve 42. Once the gas tank 34 has :: :
~ ~ 30 been evacuated, the valvès 32,42 are closed and the ;~ valves 28,40 are opened so as to establish the necessary ~: .
~ .
r ~ ~^ ' , ~ 9 ' ~
' ~ ' . ' - . ' , ~, ' ' ' ' '' , . ..
~71~1 vacuum throughout the system and direct the gaseous hydrocarbons produced through the vacuum pump 22 and into the gas tank 34.
Using the apparatus illustrated in Fig. 1 and sampling the pyrolytic products for their composition as a function of temperature provided the following results:
Table 1 Temperature Yields ~weight %) Ex. No. ( C) Oils Char Gases . ._ . -.- _ _ ;~ 1 250 8.9 91.1 0.0
The present invention relates to a process for the treatment of used rubber tires by vacuum pyrolysis to produce liquid and gaseous hydrocarbons and a solid carbonaceous material.
The accumulation of large quantities of scrap tires has become a major environmental problem. Because of their resistance to biodegradation, used automobile tires provide a favourable environment for vermin, rodents and fire. Environmental regulations, on the other hand, prohibit the disposal of such waste materials - by burning outdoors or by burial underground.
One possible solution to the above problem is to convert the tires into fuels and other useful hydro-carbon products, for instance by thermal decomposition.
In order to avoid side reactions and cross-reactions among product species when heating the tires under atmos-~: :
pheric or superatmospheric pressure, which results in ~' a very inefficient conversion process, U.S. Patent No.
4,235,676 has proposed to conduct the pyrolysis of rubber tires under sub-atmospheric pressure. According to this patent, the vacuum pyrolysis of tires is effected by moving a mass of shredded tires through an elongated tubular mem-ber maintained at a temperature between about 400~ and ,::
~ 800C, in the absence of air and/or oxygen, with the material being turned or stirred as it passes through . ~ :
the tubular member, and withdrawing the gases and vapors produced by means of a vacuum of from about 4 inches to about 6 inches of mercury (i.e. an absolute pressure of from about 608 mm Hg to about 658 mm Hg). The process conditions, however, are such as to promote the forma-~1.;;~7~151 tion of gaseous hydrocarbons to the detriment of-the more highly desirable hydrocarbon oils.
SVMMARY OF THE INVEN'rION
It is therefore an object of the present invention to carry out the pyrolysis of used rubber tires under conditions to promote the formation of liquid hydroearbons and to thereby yield higher amounts of hydrocarbon oils.
In accordance with the invention, there is thus provided a process for the treatment of used rubber tires by vacuum pyrolysis in a reactor to pro-duce liquid and gaseous hydrocarbons and a solid carbona-~ ceous material, wherein the pyrolysis of the tires is : carried out at a temperature in the range of about 360C
to about 415C, under a sub-atmospheric pressure of less than about 35 mm Hg and such that gases and vapors pro-duced in the reactor have a residence time of the order of a few seconds, whereby to increase the yield of the ; ~ liquid hydrocarbons~and lower the yields of the gaseous -: : 20 hydrocarbons and solid carbonaeeous material.
~. .
` :~ ; It has been unexpeetedly found, according to the invention, that by seleeting a pyrolysis tempera-~; ~ ture of about 360C to about 415C, preferably of about 380C to about 400C, a sub-atmospheric pressure of less .
than about 35 mm Hg, preferably of less than about ; 30 mm Hg, and a residence time of the gases and vapors : in the reactor of a few seconds, preferably 1-3 sec., and eondueting the process with sueh seleeted parameters, the yield of the highly desirable liquid hydrocarbons is signifieantly inereased while the yields of the less ;~ : desirable gaseous hydrocarbons and solid carbonaceous ,: ~
;
.
: ;- - :
.
- .
711S~
material are lowered, thereby enabling hydrocarbon oils to be obtained in substantially maximum yield. Indeed, it has been observed that if the tires are treated at a temperature above 415C, there is a gasification of the residual solid carbonaceous material, producing more gaseous hydrocarbons without formation of any further liquid hydrocarbons. On the other hand,operat-ing under a sub-atmosphexic pressure greater than 35 mm Hg has been found to promote the formation of gaseous hydrocarbons to the detriment of the liquid hydrocarbons; a too long residence time of the gases and vapors in the reactor, i.e. exceeding a few seconds, , ~
- also has the same detrimental effect.
The used rubber tires, prior to undergoing pyrolysis, are preferably shredded into cuttings. Such tire cuttings may have a mesh size of about 5-15 mm, for example.
-; According to a preferred embodiment of the invention, the reactor used for carrying the pyrolysis is ;~20 a multi-tray reactor having a plurality of spaced-apart heated trays arranged above one another and each adapted to receive a bed of the tire cuttings for subjecting :. -i~:
same to the pyrolysis. The trays are heated at tempera-~ tures to provide a vertical temperature gradient between ;j25 uppermost and lowermost trays with the lowermost tray being heated at a temperature higher than the uppermost ~-tray. For example, the uppermost and lowermost trays may be heated at about 250C and about 500C, respect-ively: it should be understood, however, that the bed Of tire cuttings even lf heated by means of a tray main-tained at a temperature of about 500C is not allowed .
~L2~ 5~
to reach a temperature exceeding about 415C and this may be achieved by controlling the residence time of the tire cuttings on such a tray.
Such a multi-tray reactor is advantageously provided with a plurality of discharge outlets each associated with a respective tray for discharging gaseous - hydrocarbons and condensable hydrocarbon vapors generated in the reactor. These gaseous hydrocarbons and condens-able hydrocarbon vapors are withdrawn from the reactor through the discharge outlets and passed through heat exchanger means for condensing the condensable hydrocarbon vapors to thereby obtain the liquid hydrocarbons. To this end, the discharge outlets are connected via the heat exchanger means to vacuum means for maintaining the sub-atmospheric pressure in the reactor and causing the ,~
gaseous hydrocarbons and condensable hydrocarbon vapors to flow out of the reactor through the discharge outlets.
, Preferably, the heat exchanger means include primary and secondary heat exchanger means, the primary heat exchanger means comprising a plurality of heat exchanger elements each connected to a respective dischar-ge`outlet. The heat exchanger elements are maintained at temperatures to provide a vertical temperature gra-dlent between uppermost and lowermost heat exchanger ~ 25 elements with the lowermost heat exchanger element being ;~ mdintained at a temperature higher than the uppermost ~ -:
heat exchanger element. For example, the uppermost and lowermost heat exchanger elements may be maintained at about 10C and about 40C, respectively. The secondary heat exchanger means, on the other hand, may comprise a plurality o~ condensation traps in fluid flow communi-.
:: _ 5 , ,. :, ~ ~: , . - . . . .
, - . - - - , Li5~L
cation with one another. Thus, the gaseous hydrocarbons and condensable hydrocarbon vapors after having passed through the prlmary heat exchanger means are passed into the condensable traps from one to another. For example, the gaseous hydrocarbons and condensable hydrocarbon vapors may be first passed into a condensation trap main-tained at a temperature of about -20C and then into the other condensation traps which are maintained at a tempe-- rature of about -80C.
; 10 As indicated above, the process according to ~` the invention enables used rubber tires to be converted into high amounts of liquid hydrocarbons. Typically, about 60 weight ~ liquid hydrocarbons, about 38 weight solid carbonaceous material and about 2 weight ~ gaseous hydrocarbons can be produced from used rubber tires by , ~ ~ the~process of the invention. The liquid hydrocarbons - ~ produced in accordance with the invention have a calorific va~lue of about 10,200 kcal kg 1 and are thus suitable for ; use as heatlng fuel.
BRIEF DESCRIPTION OF THE DRAWINGS
~: : :
Further features and advantages of the inven-tion will become more readily apparent from the following descrlptlon of preferred embodiments thereof as illustra-ted by way of example in the accompanying drawings, in ~ which I Fig. 1 is schematic illustration of an apparatus for carrying a process accordlng to the invention' Fig. 2 is a plot of the product yield as a ~ : :
function of temperature; and Fig. 3 is a plot of the yield of liquid hydro-carbons as a function of pressure.
:
~ 6 -~L2'7~ 3l51 DESCRIPTION OF PREFERRED EMBODIMENTS
, ., . _ _ - Referring first to Fig. 1, there is illustrated an apparatus for carrying out the vacuum pyrolysis o~ used rubber tires in the form of cuttings, comprising a multi-tray reactor 10 having a plurality o~ spaced-apart heated _ .
trays 12 arranged abo~e one another and each adapted to receive a bed of tire cuttings charged into the reactor _ via the hopper 14 and transported from an upper to a lower tray by conventional means (not illustrated,) for subjecting the tire cuttings to pyrolysis. The trays 12 are heated at temperatures to provide a vertical temperature gradient between the uppermost and lowermost trays with the lowermost tray being heated at a temperature higher than the uppermost tray. Typically, the uppermost and lowermost trays are heated at about 250C and about 500C, respectively. The heating of the trays 12 and the residence time of the tire cuttings thereon are such that the tire cuttings when ~-~ reaching the lower portion of the reactor (i.e. the two ..~
lowermost trays) are treated at a temperature of about 360C
~ .
to about 415C and that the temperature of the tire cuttings does not exceed about 415C.
The reactor 12 is provided with a plurallty of discharge outlets 16 each associated with a respective ; tray~12 for discharging the gaseous hydrocarbons and condensable hydrocarbon vapors generated in the reactor.
.::
~ ~ The discharge outlets 16 are connected via primary and ..
secondary heat exchangers 18 and 20 to a vacuum pump 22 for maintaining sub-atmospheric pressure in the reactor 12 and causing the gaseous hydrocarbons and condensable hydrocarbon vapors to flow out of the reactor through the ~; ~ discharge outlets. A sub-atmospheric pressure of less than about 35 mm Hg is maintained in the reactor 12 by : ' -.:
~: . . .
.
.
~7~
means of a vacuum control device 24 connected to the vacuum line 26 and adapted to set a predetermined sub-atmospheric pressure. The vacuum line 26 which is pro-vided with a valve 28 is bifurcated into two lines, a first line 30 provided with a valve 32 and connected to a gas reservoir or tank 34 for storing the gaseous hydrocarbons produced in the reactor 12, and a second line 36 leading to the vacuum pump 22. A further line 38 provided with valves 40 and 42 interconnects the vacuum pump 22 and gas tank 34, the valve 42 being a vent valve.
The primary and secondary heat exchanger 18 and 20 through which the gaseous hydrocarbons and condensable hydrocarbon vapors are passed are adapted to condense the condensable hydrocarbon vapors to thereby obtain the desired liquid hydrocarbons. The primary heat exchanger 18 comprises a plurality of shell and tube ., heat exchanger elements 44 each connected to a respective discharge outlet 16. The heat exchanger elements 44 are .~ :
maintained at temperatures to provide a vertical tempera-ture gradient between the uppermost and lowermost heat exchanger elements wlth the lowermost heat exchanger element being maintained at a temperature higher than the uppermost heat exchanger element. Typically, the upper-~ ~ 25 most and lowermost heat exchanger elements are maintained '~ at about 10C and about 40C, respectively. About 70 -~ of the total condensable hydrocarbon vapors produced are condensed by means of the primary heat exchanger 18.
, The gaseous hydrocarbons and remaining conden-sahle hydrocarbon vapors leaving the heat exchanger " :: :
:. ~ : , ' S~
elements 44 are collected by means of the collecting conduit 46 and then passed through the secondary heat exchanger 20. The latter comprises a plurality of con-densation traps 48,50 in ~luid flow communication with one another. The first condensation trap 48 is advanta-geously maintained at a temperature of about -20C by means of a refrigerant coil52 in which an aqueous solution of ethylene glycol is circulated. The other condensa-; tion traps 50, on the other hand, are maintained at a temperature of about -80C by being immersed in acetone/C02 baths contained in thermos containers 54 supported on a wheeled vertically displaceable platform 56. A filter 58 comprising glass wool is provided for filtering the gaseous hydrocarbons from which have e~tracted any condensable hydrocarbon vapors, prior to , ~
- the gaseous hydrocarbons being sucked via lines 26,36 ~ .
through the vacuum~pump 22 and directed into the gas tank 34 via line 38.
The solid carbonaceous material which is pro-20 ~ duced in the reactor 12 as a result o~ the pyrolysis : ..
- of the tires is discharged via the bottom outlet 60 into a suitable container 62 placed underneath.
-At the start of the process, the gas tank 34 is first evacuated by closing the valves 28,40 and open-ing the valves 32,42 so that any air or other gas con-tained in the tank 34 is sucked via lines 30,36 through the vacuum pump 22 and vented to the atmosphere via line ,: : -~ 38 through the vent valve 42. Once the gas tank 34 has :: :
~ ~ 30 been evacuated, the valvès 32,42 are closed and the ;~ valves 28,40 are opened so as to establish the necessary ~: .
~ .
r ~ ~^ ' , ~ 9 ' ~
' ~ ' . ' - . ' , ~, ' ' ' ' '' , . ..
~71~1 vacuum throughout the system and direct the gaseous hydrocarbons produced through the vacuum pump 22 and into the gas tank 34.
Using the apparatus illustrated in Fig. 1 and sampling the pyrolytic products for their composition as a function of temperature provided the following results:
Table 1 Temperature Yields ~weight %) Ex. No. ( C) Oils Char Gases . ._ . -.- _ _ ;~ 1 250 8.9 91.1 0.0
2 310 20.2 79.5 0.3 ~` 3 335 29.5 68.8 1.7 `~ 15 4 363 51.5 45.6 2.9 415 61.2 36.6 2.2 ~ ~ 500 60.~ ~ 5 4.3 ., ~ .
The above data are reported in Fig. 2, in which the symbols (o), (~) and (~) represent the following:
~- 20 O : liquid hydrocarbons .
: char (solid carbonaceous material) : gaseous hydrocarbons.
As shown in Fig. 2, when the pyrolysis temperature exceeds about 415C, the yield of liquid hydrocarbons is lowered. This is due to a gasification of the char ~-~ or solid carbonaceous material, which produces more : . - , ~ ~ gaseous hydrocarbons. As it is apparent, the optimum - ; temperature range for a maximum production of liquid :
~ hydrocarbons is about 360 - 415C.
~ .
:
::
.
,~
.: ~ .. , ~ .
~27~5~
The tire cuttings used in these experiments had the following characteristics:
Elementary Analysis:
C: 85.7%
H: 7.5%
N: 0.3%
: 5.1%
S: 1.4%
Volatile matter: 65.2%
Fixed Carbon: 28.7%
Ashes: 6.1%
Calorific Value: 8,787 kcal kg 1 Size: ~ " Tyler The hydrocarbon oils produced from such tire cuttings ; 15 had the following characteristics:
Elementary Analysis-C: 87.1%
H: 10.5%
N: 0.2%
O: 1.4% :~
: ~ S: 0.8%
. Calorific Value: 10,200 kcal kg 1 ~- : Density: 0.95 g ml 1 ~: .
: ~ Humidity: 0.15%
: :
Dynamic Viscosity (21C): 168 cp : :~ : Dynamic Viscosity (49C): 46 cp Three additional experiments were carried out with~a view to illustrating the effect of pressure on :
: the yield of the Iiquid hydrocarbons. The results ~ 30 obtained are as follows:
: ' :: :
: -- 1 1 -~'7~51 _ .. ~
Absolute Pressure Yields (weight %) Ex. No.(mm Hg)Oils Char Gases . I
7 15 57.2 38.4 4.4 8 35 56.9 37.5 5.6 :~ 9 ~__ 54.5 39.8 5.7 :: .
:~ The above data for the liquid hydrocarbons only are reported in Fig. 3. As shown, when -~ the sub-atmospheric pressure is greater than about 35 mm Hg, the yield of liquid hydrocarbons is lowered. As it is apparent from Table 2, operating under an absolute pressure above 35 mm Hg promotes the formation of gaseous hydrocarbons to the detriment of the liquid ~' hydrocarbons. The sub-atmospheric pressure must there-- ~ 15 fore be maintained under about 35 mm ~g to provide a ~ maximum production of liquid hydrocarbons.
;
' :, ' ~ ' `~, : ' :
- :
~:' ,.j :
: :~
~' ~ : :
:;. - 12 -.~ ,.~.
:~ ..: - .
' :: ~ . : , .
The above data are reported in Fig. 2, in which the symbols (o), (~) and (~) represent the following:
~- 20 O : liquid hydrocarbons .
: char (solid carbonaceous material) : gaseous hydrocarbons.
As shown in Fig. 2, when the pyrolysis temperature exceeds about 415C, the yield of liquid hydrocarbons is lowered. This is due to a gasification of the char ~-~ or solid carbonaceous material, which produces more : . - , ~ ~ gaseous hydrocarbons. As it is apparent, the optimum - ; temperature range for a maximum production of liquid :
~ hydrocarbons is about 360 - 415C.
~ .
:
::
.
,~
.: ~ .. , ~ .
~27~5~
The tire cuttings used in these experiments had the following characteristics:
Elementary Analysis:
C: 85.7%
H: 7.5%
N: 0.3%
: 5.1%
S: 1.4%
Volatile matter: 65.2%
Fixed Carbon: 28.7%
Ashes: 6.1%
Calorific Value: 8,787 kcal kg 1 Size: ~ " Tyler The hydrocarbon oils produced from such tire cuttings ; 15 had the following characteristics:
Elementary Analysis-C: 87.1%
H: 10.5%
N: 0.2%
O: 1.4% :~
: ~ S: 0.8%
. Calorific Value: 10,200 kcal kg 1 ~- : Density: 0.95 g ml 1 ~: .
: ~ Humidity: 0.15%
: :
Dynamic Viscosity (21C): 168 cp : :~ : Dynamic Viscosity (49C): 46 cp Three additional experiments were carried out with~a view to illustrating the effect of pressure on :
: the yield of the Iiquid hydrocarbons. The results ~ 30 obtained are as follows:
: ' :: :
: -- 1 1 -~'7~51 _ .. ~
Absolute Pressure Yields (weight %) Ex. No.(mm Hg)Oils Char Gases . I
7 15 57.2 38.4 4.4 8 35 56.9 37.5 5.6 :~ 9 ~__ 54.5 39.8 5.7 :: .
:~ The above data for the liquid hydrocarbons only are reported in Fig. 3. As shown, when -~ the sub-atmospheric pressure is greater than about 35 mm Hg, the yield of liquid hydrocarbons is lowered. As it is apparent from Table 2, operating under an absolute pressure above 35 mm Hg promotes the formation of gaseous hydrocarbons to the detriment of the liquid ~' hydrocarbons. The sub-atmospheric pressure must there-- ~ 15 fore be maintained under about 35 mm ~g to provide a ~ maximum production of liquid hydrocarbons.
;
' :, ' ~ ' `~, : ' :
- :
~:' ,.j :
: :~
~' ~ : :
:;. - 12 -.~ ,.~.
:~ ..: - .
' :: ~ . : , .
Claims (15)
1. A process for the treatment of used rubber tires by vacuum pyrolysis in a reactor to produce liquid and gaseous hydrocarbons and a solid carbonaceous material, which comprises the steps of feeding used rubber tire material into the reactor and pyrolysing said rubber tire material at a temperature in the range of about 360°C to about 415°C, under a sub-atmospheric pressure of less than about 35 mm Hg and such that gases and vapors produced in said reactor have a residence time of the order of a few seconds, whereby to increase the yield of said liquid hydrocarbons and lower the yields of said gaseous hydrocarbons and said solid carbonaceous materials.
2. A process as claimed in claim 1, wherein said temperature is in the range of about 380°C to about 400°C.
3. A process as claimed in claim 1, wherein said sub-atmospheric pressure is less than about 30 mm Hg.
4. A process as claimed in claim 1, wherein said residence time is of about 1 second to about 3 seconds.
5. A process as claimed in claim 1, wherein said rubber tire material comprises shredded tire material comprised of tire shreds.
6. A process as claimed in claim 5, wherein said tire shreds have a mesh size of about 5 mm to about 15 mm.
7. A process as claimed in claim 5, wherein said reactor is a multi-tray reactor having a plurality of spaced-apart heated trays arranged above one another and each receiving a bed of said tire shreds with said tire shreds being transported from an upper to a lower tray and wherein said trays are heated at temperatures to provide a vertical temperature gradient between uppermost and lowermost trays with the lowermost tray being heated at a temperature higher than the uppermost trays, whereby said tire shreds while being transported towards said lowermost tray are gradually heated to said pyrolysis temperature and attain said pyrolysis temperature in a lower portion of said reactor.
8. A process as claimed in claim 7, wherein said uppermost and lowermost trays are heated at about 250°C and about 500°C, respectively, and wherein the residence time of said tire shreds on the trays of the lower portion of the reactor is controlled such that the temperature of said tire shreds does not exceed about 415°C.
9. A process as claimed in claim 7, wherein said reactor is provided with a plurality of discharge outlets each associated with a respective tray for discharging gaseous hydrocarbons and condensable hydrocarbon vapors generated in said reactor, and wherein said gaseous hydrocarbons and condensable hydrocarbon vapors are withdrawn from said reactor through said discharge outlets and passed through heat exchanger means for condensing said condensable hydrocarbon vapors to thereby obtain said liquid hydrocarbons, said discharge outlets being connected via said heat exchanger means to vacuum means for maintaining said sub-atmospheric pressure in said reactor and causing said gaseous hydrocarbons and condensable hydrocarbon vapors to flow out of said reactor through said discharge outlets.
10. A process as claimed in claim 9, wherein said heat exchanger means include primary and secondary heat exchanger means, said primary heat exchanger means comprising a plurality of heat exchanger elements each connected to a respective discharge outlet, and wherein said heat exchanger elements are maintained at temperatures to provide a vertical temperature gradient between uppermost and lowermost heat exchanger elements with the lowermost heat exchanger element being maintained at a temperature higher than the uppermost heat exchanger element.
11. A process as claimed in claim 10, wherein said uppermost and lowermost heat exchanger elements are maintained at about 10°C and about 40°C, respectively.
12. A process as claimed in claim 10, wherein said secondary heat exchanger means comprise a plurality of condensation traps in fluid flow communication with one another and wherein said gaseous hydrocarbons and condensable hydrocarbon vapors after having passed through said primary heat exchanger means are passed into said condensation traps from one to another.
13. A process as claimed in claim 12, wherein said gaseous hydrocarbons and condensable hydrocarbon vapors are first passed into a condensation trap maintained at a temperature of about -20°C and then into the other condensation traps, said other condensation trap being maintained at a temperature of about -80°C.
14. A process as claimed in claim 1, wherein said pyrolysis is carried out at temperature, sub-atmospheric pressure and gas/vapor residence time conditions such as to produce about 60 weight % liquid hydrocarbons, about 38 weight % solid carbonaceous material and about 2 weight %
gaseous hydrocarbons.
gaseous hydrocarbons.
15. A process as claimed in claim 1, wherein said pyrolysis is carried out at temperature, sub-atmospheric pressure and gas/vapor residence time conditions such as to produce liquid hydrocarbons having a calorific value of about 10,200 kcal kg-1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000509162A CA1271151A (en) | 1986-05-14 | 1986-05-14 | Production of hydrocarbon oils by vacuum pyrolysis of scrap tires |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000509162A CA1271151A (en) | 1986-05-14 | 1986-05-14 | Production of hydrocarbon oils by vacuum pyrolysis of scrap tires |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1271151A true CA1271151A (en) | 1990-07-03 |
Family
ID=4133146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000509162A Expired - Fee Related CA1271151A (en) | 1986-05-14 | 1986-05-14 | Production of hydrocarbon oils by vacuum pyrolysis of scrap tires |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1271151A (en) |
-
1986
- 1986-05-14 CA CA000509162A patent/CA1271151A/en not_active Expired - Fee Related
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4740270A (en) | Vacuum pyrolysis of scrap tires | |
| US8476480B1 (en) | Bio-oil fractionation and condensation | |
| EP0588814B1 (en) | Treatment of automobile shredder residue by vacuum pyrolysis | |
| EP2199364A2 (en) | Counter-current process for biomass conversion | |
| US4317703A (en) | Pyrolysis process utilizing pyrolytic oil recycle | |
| JPS55157679A (en) | Preparation of high-purity petroleum pitch or coke | |
| DK2390301T3 (en) | Reactor systems and method for the production of carbon-enriched solid product by increasing the carbon content | |
| CN106795437A (en) | Carbon dioxide produced by hydropyrolysis is used for the purposes of technique inerting | |
| AU649980B2 (en) | Process for steam treating carbonaceous material | |
| EP2343349A1 (en) | Device for producing torrefied wood, charcoal, wood tar, pyroligneous acid and synthesis gas | |
| CA1163595A (en) | Organic products and liquid fuels from lignocellulosic materials by vacuum pyrolysis | |
| US2456796A (en) | Hydrocarbon coking | |
| CN112930385A (en) | Method and apparatus for steam separation of pyrolysis oil | |
| EP3031881A1 (en) | Method of pyrolytic processing of polymer waste from the recycling of food packaging and a system for carrying out such method | |
| CA3135937A1 (en) | Continuous reactor device and process for treatment of biomass | |
| US3436314A (en) | Technique for converting bagasse and other moist plant substances into charcoal | |
| KR100621713B1 (en) | Upgrading solid material | |
| Vitolo et al. | Physical and combustion characterization of pyrolytic oils derived from biomass material upgraded by catalytic hydrogenation | |
| CA1271151A (en) | Production of hydrocarbon oils by vacuum pyrolysis of scrap tires | |
| US20140336427A1 (en) | Methods of and apparatuses for upgrading a hydrocarbon stream including a deoxygenated pyrolysis product | |
| Mohammed et al. | In-situ upgrading of Napier grass pyrolysis vapour over microporous and hierarchical mesoporous zeolites | |
| US4441886A (en) | Process for removing organic sulphur from coal and material resulting from the process | |
| US4839021A (en) | Treatment of petroleum derived organic sludges and oil residues | |
| US9023181B2 (en) | Fast pyrolysis catalytic cracking pipe for producing bio-oils | |
| KR20170078813A (en) | Method for the conversion of biomass to liquid and/or gaseous energy carriers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |