CA1230571A - Process for the hydrotreating of a heavy oil - Google Patents
Process for the hydrotreating of a heavy oilInfo
- Publication number
- CA1230571A CA1230571A CA000434795A CA434795A CA1230571A CA 1230571 A CA1230571 A CA 1230571A CA 000434795 A CA000434795 A CA 000434795A CA 434795 A CA434795 A CA 434795A CA 1230571 A CA1230571 A CA 1230571A
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- Prior art keywords
- reactor
- process according
- heavy oil
- bed
- hydrogen
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G49/00—Treatment of hydrocarbon oils, in the presence of hydrogen or hydrogen-generating compounds, not provided for in a single one of groups C10G45/02, C10G45/32, C10G45/44, C10G45/58 or C10G47/00
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- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
A B S T R A C T
PROCESS FOR THE HYDROTREATING OF A HEAVY OIL
A process for the hydrotreating of a heavy oil by leading the heavy oil and hydrogen at elevated temperature and pressure cocurrently in downward direction through a reactor which contains at least one bed of a solid catalyst, in which process also a hydrocarbon mixture, which is at least for the greater part in the gaseous phase at the conditions pre-vailing in the reactor, is introduced into the reactor at a point upstream of the uppermost bed of solid catalyst.
PROCESS FOR THE HYDROTREATING OF A HEAVY OIL
A process for the hydrotreating of a heavy oil by leading the heavy oil and hydrogen at elevated temperature and pressure cocurrently in downward direction through a reactor which contains at least one bed of a solid catalyst, in which process also a hydrocarbon mixture, which is at least for the greater part in the gaseous phase at the conditions pre-vailing in the reactor, is introduced into the reactor at a point upstream of the uppermost bed of solid catalyst.
Description
~:~30~
PRfCESS FOR THE HYDROTRE~TING OF A HE~VY OIL
me invention relates ~o a process for the hydrotreating of a heavy oil by leading the heavy oil and hydrogen at elevated temperature and pressure cc~urrently in dcwnward direction through a reactor which contains at least one bed of a solid catalyst.
In the context of this specification and claims the term hydrotreatment is used for conversion processes in which heavy oils are converted in the presence of hydrogen. These conversion processes camprise in particular demetallization, desulphurization, denitrogenation, asphaltene conversion and hydrocracking.
me term heavy oils is used in this specification and claims for mQxtures of hydrocarbons which are at least for the greater part in the lit~lid phase at the conditions of tt-3nperature and pressure prevailing in the reactor during normal operation of the hydrotreating process. As examples of heavy oils may be mentioned crude mineral oils, topped mineral oils, residues of atmospheric or vacuum distillation of mineral oils, deasphalted residual oils, asphalts, shale oils, oils c-~btained from tar sands.
Hydrotreatment of heavy oils is conventionally carried out by leading the oil together with hydrogen (in this specification the word hydrogen stands for pure hydrogen as well as for hydrogen-containing gases) in t~c~wnward direction thraugh a reactor which contains at least one bed of a solid catalyst. The heavy oil (also called the feed) trickles around the catalyst particles at the surface of which the reaction with hydrogen takes place. Because these reactions are exothermic, sufficient cooling capacity must be present during operation to control the temperature so as to avoid the development of undesired high temperatures which may lead 1230S7~
to deactivation of the catalyst, coke formation, plugging of ~the catalyst bed and exposing the reactor walls to higher temperatures than those for which they are designed. This cooling capacity (also called heat-sink) is provided by the hydrogen containing gas (which may include recycle gas) and the heavy oil flawing through the reactor.
Apart frcm controlling the temperature rise over all individu21 beds in the reactor the tl3mperature at the outlet of each bed has to be reduced to the desired temperature at the inlet of the next bed. This cooling is in many cases accGmplished by injection between the catalyst beds of fresh hydrogen and/or, hydrogen-containing recycle gas at a temr perature lower than the temperature prevailing in the re-actor.
1 5 Hawever it may happen that the forwarding of heavy oil or the recycle of gas to the reactors is interrupted by malfunctiomng of equipment. In particular the heavy oil flcw may be hamçered or completely disrupt~Kd. S mce the heavy oil present in the reactors will continue to react, the heat sink as provided by the gas flow on its own might become insuffi-cient then and temperatures could increase to undesirable heights (so-called "temperature runaway"). In order to avoid such a temperature runaway in case e.g. the supply of heavy oil to the reactor is decreased or interrupted, the hydro-treatment process has to be brought to a standstill bydepressurizing the reactor and discontinuing the heating of the gas and oil supply.
It would be attractive to have provisions which enable avoidance of temperature runaway in the first catalyst bed u~der all circumstances, even during an interruption of heavy oil or hydrogen supply to that first catalyst bed. It is possible to provide sufficient heat sink in the first catalyst bed - even in case of interruption of feed supply -by continuous injection of a larger amount of hydrogen and/or hydrogen containing recycle gas into the reactor upstream of 123057~
the first catalyst bed than what is normally applied for undisturbed feed flow. However, for such a purpose gas campressors with extra high capacity would be needed, which is very unattractive for technological and econamical reasons.
It has now been found that sufficient heat sink for the first catalyst bed can also be achieved by injection of a hydrocarbon muxture instead of part of a hydrogen containing gas into the reactor upstream of the uppermost (also called first) catalyst bed.
Accordingly the present invention relates to a process for the hydrotreating of a heavy oil by leading the heavy oil and hydrogen at elevated temperature and pressure cocurrently in downward direction through a rPactor which contains at least one bed of a solid catalyst, in which process also a hydrocarbon mixture, which is at least for the greater part in the gaseous phase at the conditions prevailing in the reactor, is introduced into t~e reactor at a point upstream of the uppermost bed of solid catalyst.
The hydrocarbon mixture which is at least for the 2a greater part in the gaseaus phase at the conditions pre-vailing in the reactor is very suitably braught at reactor pressure in the liquid state with the aid of a pump. In this way the need for using gas compressors with a high capacity is avercome. Part of this hydrocarbon mixture may evaporate between the said pump and its entrance into the reactor owing to heating or heat exchange with other streams.
The said hydrocarbon mixture will act as a heat sink in the first reactor bed due to its heat capacity and heat of evaporation, and it may replace part of the hydrogen-contain-3o ing gas in this respect during normal aperation. It ispreferred that such an amount of said hydrocarbon mixture is introduced into the reactor that temperature runaway in the uppermost catalyst bed does not occur when the supply of heavy oil or hydrogen is interrupted.
~Z305~1 Althcugh the presence of (part of the) said hydrocarbon mixture is needed when malfunctioning occurs, lt is of advantage and preferred to introduce continuously said hydrocarbon mlxture into the reactor , in order to avoid any risk of malfunctioning of instrumentation or equipment which might occur in the absence of this ~uxture.
It is of advantage to use independent means (e.g.
separate liquid pumps with different energy sources) for the introduction into the reactor of the said hydrocarbon mixture and the feed respectively. In that way the supply of the said hydrocarbon mixture is ascertained, even if the feed pump malfunctions or falls out completely. It is of course pos-sible to m~x the feed and the said hydrocarbon mlxture downstream of the feed pump and injecting the mixture thus obtained upstream of the first catalyst bed, provided the said hydrocarbon mixture is transported with the aid of a separate pump with a different en~rgy source.
The hydrocarbon mixture which is at least for the greater part in the gaseous phase at the conditions prevai-ling in the reactor and which is introduced into the reactor at a point ~pstream of the uppermost bed of solid catalystvery convemently consists of a fraction of the reactor effluent.
In general the effluent of the reactor which consists of hydrotreated heavy oil and a hydrogen-containing gas is separated in high temperature ("hot") separators and low temperature ("cold") separators conæ cutively, yielding gaseous and liquid products. Liquid product from the cold separators (which consists of condensable compcunds of the 3a gaseous product from the hot separators) is very suitable to be used as the said hydrocarbon mixture.
The amLunt of said hydrocarbon mixture, preferably liquid product from the cold separators, which is to be introduced in order to have available sufficient cooling 3S capacity to avoid temperature runaway in the uppermost catalyst bed under all circumstances, even in case the feed supply or the hydrogen supply is interrupted, will depend on the type of feed, the type and degree of feed conversion to be achieved dNring normal cperation, the reaction conditions and the catalyst. For each specific case the munimum amount of the said hydrocarbon mixture which is to be introduced into the reactor must be determined by experiments on a small scale and/or calculations.
In most cases it is also desirable to introduce fresh hydrogen or fresh hydrogen-containing gas and recycle gas (which consists for the greater part of molecular hydrogen) into the reactor between the catalyst beds in order to reduce the inlet temperature of the next bed and thereby avoiding temperature runaways in subsequent catalyst beds. Part or all of these gases may be replaced by the said hydrocarbon mixture, which can be introduced in the liquid phase between the catalyst beds. In general about 10% - 85% vol. of recycle gas can be replaced by a hydrocarbon mixture. Preference is given to the use of hydrocarbon mixtures of which about 70%
wt. is in the vapour phase at the conditions prevailing in the reactor.
Because of the much larger molecular weight of the vaporized part of the hydrocarbon mixture rel~tive to the recycle gas, the total volume flow of the gas flcw through the catalyst bed(s) is reduced markedly. The part of the hydrocarbon mixture which is still in the liquid phase in the reactor has an advantageous viscosity reducing effect on the heavy oil. The reduction in pressure drop achieved by these effects is very pro unced. Consequently in the process acco-ding to the invention use can be made of recycle gas compressors with a lcwer capacity (in terms of gas rate) and a lower differential pressure, as compared with a process in which as a heat sink use is made of feed and hydrogen exclu-sively.
~230571 m e composition of the catalyst will be adapted to the reaction desixed. In general supported catalysts will be used, the supports very conveniently being amorphous refrac-tory oxides (or mixtures thereof) of elements of Group II, III and IV of the Periodic Table of Elements e.g. magnesia, silica, alumina, zirconia, silica-all~nina, silica-zirconia.
Supports consisting of crystalline materials, such as zeolites may also be used.
One or more metals (and/or ccmpounds thereof) with hydrogenating activity are very suitably present onto the supports, in particular metals of Group VB, VIB, VIIB and/or VIII of the Periodic Table of Elements. For example, in case hydrodesulphurization is the most desired reaction to take place, catalysts which contain compounds of cobalt and/or nickel together with compounds of molybdenum and/or tungsten on alumina as a support are very suitable. In case hydrode-metallization is the most desired reaction, catalysts based on silica as a support and containing only compounds of molybdenum, or a combination of ccmpounds of nickel and vanadium, respectively, are very convenient.
The catalyst particles present in the beds may have any suitable form, e.g. powders, spheres, pellets, cylindrical ex~trudates, multilobed extrudates, rings and the like.
Cylindrical extrudates with a diameter from 0.5 to 2.5 mm are very suitable in general.
The reaction conditions prevailing in the reactor will be adapted to the hydrotreating reaction desired. In general temperatures from 300-450C, total pressures from 25-300 bar, hydrogen partial pressures from 25-250 bar, and space veloci-ties of 0.l-l0 kg feed per kg catalyst per hour will be very suitable.
EXWMPLE
Four hydrotreatment experiments are carried out with a short residue of a Middle East crude as feed. This feed is ~23~57~
led in all cases in downw æd direction through two reactors in series, each of which contains three beds of catalyst.
The catalyst (in the form of extrudates with 0.8 mm diameter) consists of an alumina support onto which nickel oxide and molybdenum oxide have been applied; the cata]yst is sulphided before use.
me feed of fresh hydrogen cont~;n;ng gas (95% vol. pure hydrogen, 5% vol. methane) is 225 nm3/ton feed. The off-gas of the reactors is (after removal of H2S) recycled and introduced into the reactor upstream of the first catalyst bed. The gases æe led over the catalyst cocurrently with the feed. The reactor pres Æ es æe adapted so as to have an average hydrogen partial pressure of 150 bar in all cases.
In experiments 2 and 4 half of the recycle gas is replaced by a hydrocarbon mixture of which abaut 70% wt. is in the vapour phase at the conditions prevailing in the reactors. This hydrocarbon mixture is brought to reactor pressure in the liquid phase and introduced into the first reactor upstream of the first catalyst bed after heating.
In experiments 1 (a ccmp æ ative experiment) and 2 (experiment according to the invention) the average reactor temperature is 380C. The amount of recycle gas in experiment 1 as well as the amount of recycle gas together with the amount of hydroc æbon mixture in experiment 2 are sufficient to avoid temperature runaway in case the feed flcw is inter-rupted. From the table it can be seen that the pressure drop ~p) in experiment 1 (73 b æ) is much higher than that in experiment 2 (14 bar). In order to overcome the pressure drop the pressure at the inlet of the first reactor m~st be higher 3Q in experiment 1 than in experiment 2. Accordingly the equip-ment of experiment 1 must be designed to withstand higher pressures than that of experiment 2, which of course is unattractive from an economical point of view. Moreover, the gas ccmpressor for the recycle gas can be much smaller in experiment 2 than in experiment 1.
lZ3(~571 In experiments 3 (comparative) and 4 (according to the invention), in which the average reactor temperature is 390C, the amount of recycle gas and the amounts of recycle gas plus hydrocarbon mixture, respectively, are not suffi-cient to avoid temperature runaway ~n case of feed flcwinterruption. The advantages of experiment 4 in comparison with experiment 3 as far as pressure drop (~p) and recycle gas co~,pressor capacity are concerned are similar to those of experiment 2 in ccmparison with experiment 1. Temperature runaway can be avoi~ed when operating the reactors at 390C
by increasing the hydrocarbon mixture/feed ratio to 1.83. The temperature rise in the first bed with feed flow amounts to 26C; in the absence of feed flow to 46C.
~23057~
g ,~BLE
Exp. 1 2 3 4 Space- ton feed/ 0.37 0.37 0.37 0.37 velocity m3 cat. hr Fresh gas Nm3/ton feed 225 225 225 225 flow Recycle Nm3/ton feed3640 1820 3640 1820 gas flow hydrocarbon ton/ton feed - 0.98 - 0.98 mixture flow average C 380 380 390 390 reactor temp.
temp. rise in C 23 23 44 44 first bed with feed flow temp. rise in C 46 46 runaway first bed no feed flow H2 in reactor gas %vol. 86 80 86 80 pressure drop bar 73 14 69 14 over reactors average reactor bar 175 188 175 188 pressure inlet pressurebar 212 195 209 195 first reactor
PRfCESS FOR THE HYDROTRE~TING OF A HE~VY OIL
me invention relates ~o a process for the hydrotreating of a heavy oil by leading the heavy oil and hydrogen at elevated temperature and pressure cc~urrently in dcwnward direction through a reactor which contains at least one bed of a solid catalyst.
In the context of this specification and claims the term hydrotreatment is used for conversion processes in which heavy oils are converted in the presence of hydrogen. These conversion processes camprise in particular demetallization, desulphurization, denitrogenation, asphaltene conversion and hydrocracking.
me term heavy oils is used in this specification and claims for mQxtures of hydrocarbons which are at least for the greater part in the lit~lid phase at the conditions of tt-3nperature and pressure prevailing in the reactor during normal operation of the hydrotreating process. As examples of heavy oils may be mentioned crude mineral oils, topped mineral oils, residues of atmospheric or vacuum distillation of mineral oils, deasphalted residual oils, asphalts, shale oils, oils c-~btained from tar sands.
Hydrotreatment of heavy oils is conventionally carried out by leading the oil together with hydrogen (in this specification the word hydrogen stands for pure hydrogen as well as for hydrogen-containing gases) in t~c~wnward direction thraugh a reactor which contains at least one bed of a solid catalyst. The heavy oil (also called the feed) trickles around the catalyst particles at the surface of which the reaction with hydrogen takes place. Because these reactions are exothermic, sufficient cooling capacity must be present during operation to control the temperature so as to avoid the development of undesired high temperatures which may lead 1230S7~
to deactivation of the catalyst, coke formation, plugging of ~the catalyst bed and exposing the reactor walls to higher temperatures than those for which they are designed. This cooling capacity (also called heat-sink) is provided by the hydrogen containing gas (which may include recycle gas) and the heavy oil flawing through the reactor.
Apart frcm controlling the temperature rise over all individu21 beds in the reactor the tl3mperature at the outlet of each bed has to be reduced to the desired temperature at the inlet of the next bed. This cooling is in many cases accGmplished by injection between the catalyst beds of fresh hydrogen and/or, hydrogen-containing recycle gas at a temr perature lower than the temperature prevailing in the re-actor.
1 5 Hawever it may happen that the forwarding of heavy oil or the recycle of gas to the reactors is interrupted by malfunctiomng of equipment. In particular the heavy oil flcw may be hamçered or completely disrupt~Kd. S mce the heavy oil present in the reactors will continue to react, the heat sink as provided by the gas flow on its own might become insuffi-cient then and temperatures could increase to undesirable heights (so-called "temperature runaway"). In order to avoid such a temperature runaway in case e.g. the supply of heavy oil to the reactor is decreased or interrupted, the hydro-treatment process has to be brought to a standstill bydepressurizing the reactor and discontinuing the heating of the gas and oil supply.
It would be attractive to have provisions which enable avoidance of temperature runaway in the first catalyst bed u~der all circumstances, even during an interruption of heavy oil or hydrogen supply to that first catalyst bed. It is possible to provide sufficient heat sink in the first catalyst bed - even in case of interruption of feed supply -by continuous injection of a larger amount of hydrogen and/or hydrogen containing recycle gas into the reactor upstream of 123057~
the first catalyst bed than what is normally applied for undisturbed feed flow. However, for such a purpose gas campressors with extra high capacity would be needed, which is very unattractive for technological and econamical reasons.
It has now been found that sufficient heat sink for the first catalyst bed can also be achieved by injection of a hydrocarbon muxture instead of part of a hydrogen containing gas into the reactor upstream of the uppermost (also called first) catalyst bed.
Accordingly the present invention relates to a process for the hydrotreating of a heavy oil by leading the heavy oil and hydrogen at elevated temperature and pressure cocurrently in downward direction through a rPactor which contains at least one bed of a solid catalyst, in which process also a hydrocarbon mixture, which is at least for the greater part in the gaseous phase at the conditions prevailing in the reactor, is introduced into t~e reactor at a point upstream of the uppermost bed of solid catalyst.
The hydrocarbon mixture which is at least for the 2a greater part in the gaseaus phase at the conditions pre-vailing in the reactor is very suitably braught at reactor pressure in the liquid state with the aid of a pump. In this way the need for using gas compressors with a high capacity is avercome. Part of this hydrocarbon mixture may evaporate between the said pump and its entrance into the reactor owing to heating or heat exchange with other streams.
The said hydrocarbon mixture will act as a heat sink in the first reactor bed due to its heat capacity and heat of evaporation, and it may replace part of the hydrogen-contain-3o ing gas in this respect during normal aperation. It ispreferred that such an amount of said hydrocarbon mixture is introduced into the reactor that temperature runaway in the uppermost catalyst bed does not occur when the supply of heavy oil or hydrogen is interrupted.
~Z305~1 Althcugh the presence of (part of the) said hydrocarbon mixture is needed when malfunctioning occurs, lt is of advantage and preferred to introduce continuously said hydrocarbon mlxture into the reactor , in order to avoid any risk of malfunctioning of instrumentation or equipment which might occur in the absence of this ~uxture.
It is of advantage to use independent means (e.g.
separate liquid pumps with different energy sources) for the introduction into the reactor of the said hydrocarbon mixture and the feed respectively. In that way the supply of the said hydrocarbon mixture is ascertained, even if the feed pump malfunctions or falls out completely. It is of course pos-sible to m~x the feed and the said hydrocarbon mlxture downstream of the feed pump and injecting the mixture thus obtained upstream of the first catalyst bed, provided the said hydrocarbon mixture is transported with the aid of a separate pump with a different en~rgy source.
The hydrocarbon mixture which is at least for the greater part in the gaseous phase at the conditions prevai-ling in the reactor and which is introduced into the reactor at a point ~pstream of the uppermost bed of solid catalystvery convemently consists of a fraction of the reactor effluent.
In general the effluent of the reactor which consists of hydrotreated heavy oil and a hydrogen-containing gas is separated in high temperature ("hot") separators and low temperature ("cold") separators conæ cutively, yielding gaseous and liquid products. Liquid product from the cold separators (which consists of condensable compcunds of the 3a gaseous product from the hot separators) is very suitable to be used as the said hydrocarbon mixture.
The amLunt of said hydrocarbon mixture, preferably liquid product from the cold separators, which is to be introduced in order to have available sufficient cooling 3S capacity to avoid temperature runaway in the uppermost catalyst bed under all circumstances, even in case the feed supply or the hydrogen supply is interrupted, will depend on the type of feed, the type and degree of feed conversion to be achieved dNring normal cperation, the reaction conditions and the catalyst. For each specific case the munimum amount of the said hydrocarbon mixture which is to be introduced into the reactor must be determined by experiments on a small scale and/or calculations.
In most cases it is also desirable to introduce fresh hydrogen or fresh hydrogen-containing gas and recycle gas (which consists for the greater part of molecular hydrogen) into the reactor between the catalyst beds in order to reduce the inlet temperature of the next bed and thereby avoiding temperature runaways in subsequent catalyst beds. Part or all of these gases may be replaced by the said hydrocarbon mixture, which can be introduced in the liquid phase between the catalyst beds. In general about 10% - 85% vol. of recycle gas can be replaced by a hydrocarbon mixture. Preference is given to the use of hydrocarbon mixtures of which about 70%
wt. is in the vapour phase at the conditions prevailing in the reactor.
Because of the much larger molecular weight of the vaporized part of the hydrocarbon mixture rel~tive to the recycle gas, the total volume flow of the gas flcw through the catalyst bed(s) is reduced markedly. The part of the hydrocarbon mixture which is still in the liquid phase in the reactor has an advantageous viscosity reducing effect on the heavy oil. The reduction in pressure drop achieved by these effects is very pro unced. Consequently in the process acco-ding to the invention use can be made of recycle gas compressors with a lcwer capacity (in terms of gas rate) and a lower differential pressure, as compared with a process in which as a heat sink use is made of feed and hydrogen exclu-sively.
~230571 m e composition of the catalyst will be adapted to the reaction desixed. In general supported catalysts will be used, the supports very conveniently being amorphous refrac-tory oxides (or mixtures thereof) of elements of Group II, III and IV of the Periodic Table of Elements e.g. magnesia, silica, alumina, zirconia, silica-all~nina, silica-zirconia.
Supports consisting of crystalline materials, such as zeolites may also be used.
One or more metals (and/or ccmpounds thereof) with hydrogenating activity are very suitably present onto the supports, in particular metals of Group VB, VIB, VIIB and/or VIII of the Periodic Table of Elements. For example, in case hydrodesulphurization is the most desired reaction to take place, catalysts which contain compounds of cobalt and/or nickel together with compounds of molybdenum and/or tungsten on alumina as a support are very suitable. In case hydrode-metallization is the most desired reaction, catalysts based on silica as a support and containing only compounds of molybdenum, or a combination of ccmpounds of nickel and vanadium, respectively, are very convenient.
The catalyst particles present in the beds may have any suitable form, e.g. powders, spheres, pellets, cylindrical ex~trudates, multilobed extrudates, rings and the like.
Cylindrical extrudates with a diameter from 0.5 to 2.5 mm are very suitable in general.
The reaction conditions prevailing in the reactor will be adapted to the hydrotreating reaction desired. In general temperatures from 300-450C, total pressures from 25-300 bar, hydrogen partial pressures from 25-250 bar, and space veloci-ties of 0.l-l0 kg feed per kg catalyst per hour will be very suitable.
EXWMPLE
Four hydrotreatment experiments are carried out with a short residue of a Middle East crude as feed. This feed is ~23~57~
led in all cases in downw æd direction through two reactors in series, each of which contains three beds of catalyst.
The catalyst (in the form of extrudates with 0.8 mm diameter) consists of an alumina support onto which nickel oxide and molybdenum oxide have been applied; the cata]yst is sulphided before use.
me feed of fresh hydrogen cont~;n;ng gas (95% vol. pure hydrogen, 5% vol. methane) is 225 nm3/ton feed. The off-gas of the reactors is (after removal of H2S) recycled and introduced into the reactor upstream of the first catalyst bed. The gases æe led over the catalyst cocurrently with the feed. The reactor pres Æ es æe adapted so as to have an average hydrogen partial pressure of 150 bar in all cases.
In experiments 2 and 4 half of the recycle gas is replaced by a hydrocarbon mixture of which abaut 70% wt. is in the vapour phase at the conditions prevailing in the reactors. This hydrocarbon mixture is brought to reactor pressure in the liquid phase and introduced into the first reactor upstream of the first catalyst bed after heating.
In experiments 1 (a ccmp æ ative experiment) and 2 (experiment according to the invention) the average reactor temperature is 380C. The amount of recycle gas in experiment 1 as well as the amount of recycle gas together with the amount of hydroc æbon mixture in experiment 2 are sufficient to avoid temperature runaway in case the feed flcw is inter-rupted. From the table it can be seen that the pressure drop ~p) in experiment 1 (73 b æ) is much higher than that in experiment 2 (14 bar). In order to overcome the pressure drop the pressure at the inlet of the first reactor m~st be higher 3Q in experiment 1 than in experiment 2. Accordingly the equip-ment of experiment 1 must be designed to withstand higher pressures than that of experiment 2, which of course is unattractive from an economical point of view. Moreover, the gas ccmpressor for the recycle gas can be much smaller in experiment 2 than in experiment 1.
lZ3(~571 In experiments 3 (comparative) and 4 (according to the invention), in which the average reactor temperature is 390C, the amount of recycle gas and the amounts of recycle gas plus hydrocarbon mixture, respectively, are not suffi-cient to avoid temperature runaway ~n case of feed flcwinterruption. The advantages of experiment 4 in comparison with experiment 3 as far as pressure drop (~p) and recycle gas co~,pressor capacity are concerned are similar to those of experiment 2 in ccmparison with experiment 1. Temperature runaway can be avoi~ed when operating the reactors at 390C
by increasing the hydrocarbon mixture/feed ratio to 1.83. The temperature rise in the first bed with feed flow amounts to 26C; in the absence of feed flow to 46C.
~23057~
g ,~BLE
Exp. 1 2 3 4 Space- ton feed/ 0.37 0.37 0.37 0.37 velocity m3 cat. hr Fresh gas Nm3/ton feed 225 225 225 225 flow Recycle Nm3/ton feed3640 1820 3640 1820 gas flow hydrocarbon ton/ton feed - 0.98 - 0.98 mixture flow average C 380 380 390 390 reactor temp.
temp. rise in C 23 23 44 44 first bed with feed flow temp. rise in C 46 46 runaway first bed no feed flow H2 in reactor gas %vol. 86 80 86 80 pressure drop bar 73 14 69 14 over reactors average reactor bar 175 188 175 188 pressure inlet pressurebar 212 195 209 195 first reactor
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the hydrotreating of a heavy oil by leading the heavy oil and hydrogen at elevated temperature and pressure cocurrently in downward direction through a reactor which contains at least one bed of a solid catalyst, in which process also a hydrocarbon mixture, which is at least for the greater part in the gaseous phase at the conditions prevailing in the reactor, is introduced into the reactor at a point upstream of the upper-most bed of solid catalyst.
2. A process according to claim 1, in which the said hydro-carbon mixture is brought at reactor pressure in the liquid state with the aid of a pump.
3. A process according to claim 1, in which the said hydro-carbon mixture is introduced continuously.
4. A process according to claim 1, in which the said hydro-carbon mixture is a fraction of the reactor effluent.
5. A process according to claim 1, in which the said hydro-carbon mixture is obtained as liquid product from a low tempera-ture separator of the reactor effluent.
6. A process according to claim 1, in which the said hydro-carbon mixture is introduced into the reactor by means independent of the means of introduction of the heavy oil to be hydrotreated.
7. A process according to claim 1, in which the amount of said hydrocarbon mixture introduced into the reactor is such that temperature runaway in the uppermost catalyst bed does not occur if the supply of heavy oil or the hydrogen supply is interrupted.
8. A process according to claim 1, in which the catalyst comprises one or more of the metals of Group VB, VIB, VIIB and/or VIII of the Periodic Table of Elements and/or compounds thereof, supported on an amorphous refractory oxide of elements of Group II, III and IV of the Periodic Table of Elements.
9. A process according to claim 1, which is carried out at a temperature of 300-450°C, a total pressure of 25-300 bar, a partial hydrogen pressure of 25-250 bar and a space velocity of 0.1-10 kg feed per kg catalyst per hour.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8224533 | 1982-08-26 | ||
| GB8224533 | 1982-08-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1230571A true CA1230571A (en) | 1987-12-22 |
Family
ID=10532535
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000434795A Expired CA1230571A (en) | 1982-08-26 | 1983-08-17 | Process for the hydrotreating of a heavy oil |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0102112B1 (en) |
| JP (1) | JPS5958090A (en) |
| CA (1) | CA1230571A (en) |
| DE (1) | DE3378691D1 (en) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL258576A (en) * | 1959-12-04 | |||
| DE1248845B (en) * | 1960-05-17 | 1967-08-31 | Shell Int Research | Process for heating hydrocarbon oils for the purpose of catalytic hydrogenating refining |
| NL7406226A (en) * | 1974-05-09 | 1975-11-11 | Shell Int Research | METHOD AND EQUIPMENT FOR THE HYDROGENING TREATMENT OF A LIQUID PETROLEUM FRACTION. |
| GB1523992A (en) * | 1976-07-06 | 1978-09-06 | Shell Int Research | Process for hydrotreating of oils |
| JPS54103775A (en) * | 1978-02-03 | 1979-08-15 | Nippon Steel Corp | Contact reactor |
| JPS5757790A (en) * | 1980-09-25 | 1982-04-07 | Idemitsu Kosan Co Ltd | Hydrogenation treatment of heavy oil |
| JPS5896685A (en) * | 1981-12-03 | 1983-06-08 | Mitsubishi Heavy Ind Ltd | Hydrogenation process |
| JPS58149988A (en) * | 1982-03-03 | 1983-09-06 | Mitsubishi Heavy Ind Ltd | Hydrogenation method |
-
1983
- 1983-08-01 EP EP19830201140 patent/EP0102112B1/en not_active Expired
- 1983-08-01 DE DE8383201140T patent/DE3378691D1/en not_active Expired
- 1983-08-17 CA CA000434795A patent/CA1230571A/en not_active Expired
- 1983-08-24 JP JP15337083A patent/JPS5958090A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0102112B1 (en) | 1988-12-14 |
| EP0102112A3 (en) | 1986-09-03 |
| JPS5958090A (en) | 1984-04-03 |
| EP0102112A2 (en) | 1984-03-07 |
| DE3378691D1 (en) | 1989-01-19 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |