JPS584077B2 - Saiseikanouna Yuukaibaitaichiyuudeno Tankasisono Bunkai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the decomposition of hydrocarbon feedstocks at high temperatures in renewable alkali metal carbonate melting media, and in particular to the decomposition of hydrocarbon feedstocks containing glass-forming oxides such as oxides of boron. Cracking heavy hydrocarbon feedstocks, such as gas oil, crude oil, atmospheric or vacuum residues, in a metal carbonate melting medium to produce cracked hydrocarbon products such as ethylene and carbonaceous materials. Regarding things.

At least a portion of the carbonaceous material or coke formed during the cracking process is degassed by contacting the carbonaceous material at elevated temperature with a gas stream containing oxygen, water vapor, or carbon dioxide reagents in a melting medium for melt regeneration. be converted into

This cracked hydrocarbon product has uses in the synthesis of polymers and other valuable drugs.

It is known in the art to pyrolyze hydrocarbons at high temperatures to produce olefin compounds such as ethylene using molten salts such as eutectic mixtures of lithium chloride and potassium chloride as the heat transfer medium.

The cracking of hydrocarbon feedstocks in molten heat transfer media such as lead for the production of ethylene is also evident in the art.

The main difficulty encountered with conventional delineation techniques, such as molten lead, is that the carbonaceous particles produced during the cracking operation are not sufficiently dispersed in the melt, forming a separate phase and contaminating the liquid and gaseous products. That's true.

Additionally, in melting media that partially suspend coke, such as lithium-potassium eutectic chloride, the accumulation of the above carbonaceous materials in or above the melting media is due to the physical removal of carbonaceous particles from the melt. Additional steps were required.

Furthermore, many contact media have been proposed in the literature to enable thermal cleavage of hydrocarbon feedstocks, including metals, alloys, slags, basalts, and glasses (Czechoslovakya Patent No. 1
No. 09,952, U.S. Pat. No. 3,647,358).

that a hydrocarbon feedstock can be decomposed in a molten alkali metal carbonate, alkali metal hydroxide, or a mixture thereof to form an ethylene-containing hydrocarbon product, and then the melting medium can be regenerated by intimate contact with oxygen or steam; have been proposed (U.S. Pat. Nos. 3,553,279, 3,252,773, 3,252,774, 3,
No. 505,018, No. 3,438,727, No. 3, 4
No. 38,728, No. 3,438,733, No. 3,43
No. 8,734, No. 3,516,796, No. 3,551
, No. 108, Oil and Gas Journal 9
Monthly 27th issue, 1971, Germany DT-082149
291).

Although the molten alkali metal carbonate melt tends to absorb or disperse the coke formed during the cracking reaction, the degree of coke dispersion is relatively small.

This limited coke dispersion in the melting medium can make the process difficult in a commercial setting.

Recently, it has been proposed to crack hydrocarbon feedstocks in renewable melting media containing alkali oxides in combination with glass-forming oxides, such as oxides of boron (U.S. Pat.
No. 850,742).

Although the melting media described above disperse the coke well, they have the disadvantage of corrosivity, which gives rise to important problems in construction.

An alkali metal carbonate melting medium containing a small amount of a glass-forming oxide selected from the group consisting of boron, vanadium, silicon, phosphorous oxides and mixtures thereof and a hydrocarbon feedstock from about 1,370 yen .1℃ (2
Hydrocarbon feedstocks are transformed to produce light olefins such as ethylene in high yields by contacting the cracked hydrocarbon products with carbonaceous materials at temperatures in the range of 500°F (500°F) for a period sufficient to form carbonaceous materials. It was discovered that it can be manufactured.

The carbonaceous material produced during the cracking operation and dispersed in the melting medium is then treated with a gas stream containing oxygen, water vapor, or carbon dioxide, and mixtures thereof, from approximately the melting point of said medium to
The melting medium is contacted at a temperature in the range of 8.9°C (3000°F) for a period of time to regenerate.

It has been found that not all oxides of primary and secondary glass-forming compounds known in the art are compatible with the process of the present invention.

In particular, primary glass-forming elements such as germanium, arsenic, and antimony have been found to be unsuitable for the decomposition or gasification processes described herein because:

That is, oxides of these elements, namely germanium,
The glass-forming oxides of arsenic and antimony are excessively reduced to their metallic state in the presence of carbon at temperatures commonly used for decomposition or gasification of hydrocarbon feedstocks.

Given the fact that in order to achieve a thermally balanced system and maintain a steady-state coke concentration in the melt, it is preferable to gasify only the amount of coke that is being formed in the cracking zone, the following In the practice of this process, some carbon in the form of coke is usually present in the melting medium.

Additionally, the two primary glass-forming oxides that are not significantly reduced by carbon, namely the oxides of molybdenum and tungsten, when used in small quantities in molten alkali metal carbonate media, can help dispersion of the carbonaceous material formed during the cracking operation. Not effective for increasing

Furthermore, the secondary glass-forming oxide, bismuth oxide, is similarly reduced to its metallic state in the presence of carbon at elevated temperatures in the melting medium.

The glass-forming oxides of the present invention are alkali metal (group IA)
Used in combination with carbonates, i.e. lithium, sodium, potassium, cesium carbonates, or mixtures thereof.

The melting medium may further contain other Group IA or Group nA components, such as oxides, hydroxides, sulfides, sulfites, or sulfates of Naglag, lithium, potassium, cesium, magnesium, calcium, strontium, Barywum. can include.

Alkali metal sulfites, sulfates, sulfides are formed there during the decomposition reaction or the subsequent gasification reaction by reaction of the sulfur contaminants in the feedstock with the alkali or alkali metal components of the melt.

Alkali metal oxides are also generated in situ by carbon reduction of alkali metal carbonates.

If water is present in the decomposition or gasification zone, alkali metal hydroxides may be produced.

The amount of glass-forming oxides in the total melting medium is based on the total melting medium, such as B20s, V205, S102, P
between about 0.1 and 25% by weight, calculated as 205;
Preferably it is maintained between 1 and about 20% by weight, more preferably between about 1 and about 12% by weight.

It should be understood that glass-forming elements such as boron can exist in different valence states at various points in the process.

Accordingly, the expression "oxide of boron" is intended to encompass any oxide of the applicable elements, such as boron, vanadium, silicon, phosphorus.

The advantage of cracking hydrocarbon feedstocks, especially sulfur-containing heavy hydrocarbon feedstocks, with the above melting media is that the melting media of the present invention (
a) homogeneously suspending the carbonaceous material formed in situ during the cracking operation in the melt; and (b) rapid gasification of said carbonaceous material when subsequently contacted with an oxygen- or water vapor-containing gas stream at an elevated temperature. It is possible to promote this.

Thus, the present invention enables the pyrolysis of heavy hydrocarbon feedstocks such as atmospheric or vacuum resid.

Cracking of the above raw materials has hitherto not been easy due to excessive coking in tubular reactors.

Furthermore, since the heavy hydrocarbon feedstocks discussed below, such as residual oils and crude oils, generally contain sulfur, such as thiols, thiophenes, and sulfides, the melting media of the present invention may be Retaining the sulfur compounds produced during combustion of carbonaceous materials provides the additional benefit of significantly reducing pollutant emissions into the atmosphere.

Furthermore, when the cracking process is carried out essentially in the absence of water vapor, the sulfur initially present in the hydrocarbon feedstock is removed, especially since most of the hydrogen sulfide produced during the cracking operation is retained by the melt. Impurities are retained by the melting medium of the present invention.

Further, a portion of the sulfur impurities present in the carbonaceous material is eluted from the carbonaceous material by the melting medium of the present invention,
Therefore, it is thought to be effective in further removing sulfur from carbonaceous materials.

Additionally, the melting media of the present invention have the additional advantage of being relatively non-corrosive, especially when compared to melting media containing major amounts of glass-forming oxides.

Therefore, maintaining the concentration of glass-forming oxides below about 25% by weight, preferably below about 20% by weight, and more preferably below 12% by weight makes it possible to maintain the concentration of glass-forming oxides as a major component in the molten media decomposition process. reduce container problems associated with using .

Yet another advantage is that the melting media of the present invention provide increased desulfurization rates at a given temperature.

The fact that the desulfurization rate decreases significantly with increasing temperature in molten alkali carbonate media requires that the molten medium often be cooled during the desulfurization process in order to obtain a satisfactory desulfurization rate.

However, during the desulfurization of the melting medium by water vapor and carbon dioxide,
It has been found that water vapor conversion, or overall desulfurization rate, is increased by adding glass-forming oxides to the molten alkali carbonate medium.

Therefore, a molten alkali carbonate medium containing glass-forming oxides can be desulfurized with water vapor and carbon dioxide in the same proportions at higher temperatures than a molten alkali carbonate melt without glass-forming oxides, where the molten medium is desired. Reduces the amount of cooling and reheating required to return to reaction temperature.

Therefore, the only requirement for the melting medium of the present invention is that the carbonaceous material produced during the separation reaction is uniformly dispersed throughout the melt and then brought into contact with a gas stream containing oxygen or water vapor or carbon dioxide at an elevated temperature. A sufficient amount of glass-forming oxide is used to promote rapid gasification of the carbonaceous material.

The use of the term "glass-forming oxide" does not imply that all of the above melting media can be rapidly cooled without crystallization.

As noted above, as long as a sufficient amount of glass-forming oxide is used to disperse the by-product carbonaceous material, or coke, the melting media of the present invention may be combined with other components such as metal and non-metal oxides, sulfides, sulfates, It should be noted that it can be used in combination with various amounts of and various other salts.

Although the melting medium of the present invention is described as an alkali metal carbonate and a glass-forming oxide, it is believed that the glass-forming oxide is formed when the glass-forming oxide is combined with an alkali metal carbonate or other alkali metal compound and heated to a molten state. It is to be understood that it is clearly within the scope of the present invention to define compounds using the melting medium of the present invention.

For example, a melting medium containing an alkali metal carbonate (M2CO3) and boron oxide (B203) as the glass-forming oxide can also be expressed in the melted state as an alkali metal borate according to the following reaction.

B203+XM2C03→XM20・B203+XCO
2 However, X ranges from 1 to 3 depending on the alkali metal used.

Therefore, it is within the scope of the invention to use the above-described alkali metal carbonates and glass-forming oxides in combination with alkali metal salts of the glass-forming oxide used, such as alkali metal borates, as the melting medium of the invention. It is.

It should be understood that any of the fused glass melts of the present invention can be made by melting the appropriate combination of raw materials.

Upon heating, a glass-forming oxide or alkali metal salt of a glass-forming oxide is formed which is used in combination with an alkali metal carbonate.

The most preferred individual renewable melting media are those obtained when an oxide of boron is used as the glass-forming oxide.

The most preferred melt system of the invention is lithium and nag.
Consists of boron oxide in combination with lagoon carbonate and mixtures thereof.

The most preferred alkali metal carbonate is a mixture of a large amount of sodium carbonate and a small amount of lithium carbonate.

In this process, a wide range of raw materials can be converted to produce light olefins such as ethylene in high yields.

In general, any hydrocarbon feedstock such as low boiling hydrocarbons, such as ethane, propane, butane, and high boiling hydrocarbons, such as naphtha, gas oil, etc., can be cracked in the melting medium.

Preferred hydrocarbon feedstocks of the present invention include heavy hydrocarbon feedstocks containing from about 2 to about 6% sulfur, such as crude oil, heavy residues, atmospheric and vacuum residues, crude residues, pitch, asphalt, etc. The heavy hydrocarbons are pinch-forming residual oils, coal, coal tar or distillate oils, natural tars, and mixtures thereof.

Preferably, the hydrocarbon feedstock that is cracked in the stable melting media of the present invention comprises a hydrocarbon feedstock that includes materials that boil above about 400°F (204.4°C) at atmospheric pressure.

Preferred hydrocarbon feedstocks that can be used in the practice of this invention include crude oils, aromatic tars, atmospheric or vacuum residues containing materials that boil above about 343.3°C (650°F) at atmospheric pressure. including.

Aromatic tars, atmospheric or vacuum residues are particularly preferred.

Although not essential to the reaction, an inert diluent can be used to adjust the hydrocarbon partial pressure in the molten media cracking zone.

The inert diluent should normally be used in a molar ratio of from about 1 to about 50 moles of diluent per mole of hydrocarbon feedstock, more preferably from 1 to 10 moles.

Examples of diluents that can be used are helium, carbon dioxide, nitrogen, water vapor, and methane.

The invention can be further understood by reference to the accompanying drawing (FIG. 1).

Contains about 2 to about 6% sulfur, about 343.3% at normal pressure
It has a boiling point above 650'F
A heavy hydrocarbon residue fraction having a carbon content of 12 is sent via line 1 to cracking zone 2 .

A molten bed is maintained within the disassembly 2 containing oxides of boron and alkali metal carbonates consisting of a large amount of sodium carbonate and a small amount of lithium carbonate.

Liquid hydrocarbon feed through line 1 is introduced into cracker 2 by bubbling the feed through melting medium 3 .

On the other hand, as the hydrocarbon feedstock passes through the reactor, the melting medium can be sprayed into the reactor or dripped onto the reaction walls.

The melting medium can flow co-currently or counter-currently to the hydrocarbon feed stream.

In both cases, means should be provided to bring the raw material into intimate contact with the melting medium.

To produce cracked hydrocarbon products and carbonaceous material, the temperature of the melting medium 3 is adjusted to about 648.9-1093.3°C (
1200-2000°F), preferably about 704°F.
Maintain at about 1300-1700°F.

As will be described later, the temperature of the melting medium is maintained within the above range by an exothermic gasification reaction of a portion of the carbonaceous material produced during the decomposition reaction.

The melting medium then provides heat for the cracking operation.

Depending on the temperature and the particular type of hydrocarbon feedstock, the rate at which the feedstock is fed through line 1 to cracking zone 2 ranges from about 0.1 to about 1
00 W/W/hour (raw material weight/melt weight/hour), preferably about 0.1 to about 20 W/W/hour.

Since pressure is not an important feature of the invention, reduced pressures may be used, for example in the range of 0.1 atm to about 50 atm, preferably from about 1 to about 50 atm.
The reaction can be carried out at about 10 atmospheres.

The amount of time that the raw materials are in contact with the melt 3, ie, the reaction time, expressed as residence time, is from about 0.01 to about 20 seconds, preferably from about 0.3 to about 5.0 seconds.

After the hydrocarbon feedstock has been cracked in the melting medium at the desired temperature and pressure, the gaseous effluent leaving the melting medium 3 passes overhead from the cracking zone 2 and is collected by line 4.

The decomposition products passing through line 4 are cooled by being exposed to a quenching medium introduced by line 5.

The cracked products are then further cooled in order to condense and separate the liquid products from the gaseous products containing light olefins by sending the quenched products via line 6 to a fractionation zone, not shown. .

A large portion of the hydrogen sulfide produced during the cracking operation is absorbed by the melt, especially when the cracking operation is carried out in the absence of substantial amounts of water vapor.

The product distribution obtained by cracking a hydrocarbon feedstock in the manner described above is substantially the same as the product distribution obtained when the same feedstock is subjected to the well-known steam cracking process under the same conditions.

A great advantage of using the melting medium of the present invention is that the carbonaceous material produced during the above decomposition process becomes more homogeneously suspended in the melt, and that the oxidizing gas is removed at high temperatures for rapid regeneration of the melting medium. That is, it can be gasified, ie, combusted, into gaseous products when brought into contact with a gasifying agent such as air, water vapor, or carbon dioxide.

The melting medium containing suspended carbonaceous material is therefore removed from the decomposition body 2 via line 7 and sent via line 7 to gasification zone 8 .

The rate at which the melting medium is removed from the cracking zone depends on the type of hydrocarbon feedstock being pyrolyzed and the rate at which the feedstock is introduced into the cracking zone 2.

Preferably, a steam lift is used to circulate the melting medium from cracking zone 2 to gasification zone 8 via line 7.

Although the above carbonaceous materials are produced in situ during the cracking of the hydrocarbon feedstock as described above, various grades of coal, polygnite ( It is clearly within the scope of the present invention to gasify carbonaceous materials which can be added in the form of various types of coke such as carbonaceous coke, lignite, coal coke and petroleum coke, beets, graphite, charcoal, etc. Let me emphasize that.

A gasification reaction is carried out by contacting the carbonaceous material in the melting medium 9 with a gasification agent introduced into the gasification zone 8 by line 10.

The gasification reaction takes place from approximately the melting point of the melting medium to approximately 1648.9C.
(3000°F) or higher and pressures ranging from reduced pressure to about 100 atmospheres.

Preferably, the temperature at which the gasification reaction is carried out is from about 648.9 to
1093.3°C (about 1200-2000°F), preferably about 760-982.2°C (about 1400-1800°F)
F).

Preferably, the pressure in the gasification zone is maintained between 1 and about 10 atmospheres.

When using an oxygen-containing gas stream as the gasifying agent for melting media regeneration, the amount of oxygen that must be present in the gas stream is:
from about 1 to about 100% by weight oxygen, preferably from about 10 to about 25%
Weight%.

Typically, the oxygen-containing gas flow is approximately o. oiw/w7 hours (
(weight of oxygen/weight of melting medium/hour) or less to about 50 W/
at a rate of W/hour, preferably from about 0.01 to about 10 W/hour.
Pass the melting medium 9 at a rate of W/h.

Most preferably, for rapid regeneration of the melting medium,
Air at approximately 37.8~5378°C (approximately 100~1000°C)
'F) via line 10.

When using water vapor as the gasifying agent, the amount of water vapor required to be present in the gas stream is from about 10 to 100% by weight, preferably from about 50 to about 100% by weight.

Water vapor is supplied by line 10 to approximately 148.9 to 537.8
At a temperature of about 300 to 1000'F, about 7.03 to
35.15kg/cTL gauge pressure (approximately 100-500p
sig) to regenerate the melting medium.

When using a carbon dioxide-containing gas stream as a gasifying agent,
The amount of carbon dioxide that needs to be present in the gas stream is approximately 10
~100% by weight.

Preferably, the temperature and pressure at which carbon dioxide is introduced into gasification zone 8 are about 37.8-537.8°C (about 100-100°C, respectively).
00°F), and approximately 7.03-70.3 kg/cd gauge pressure (100-1000 psig).

The specific gasification rate of carbonaceous material in a particular renewable melting medium, defined as the amount of carbonaceous material gasified per cubic foot of melt in one hour, is determined by the temperature at which the gasification step is conducted; It is related to the residence time of the oxygen-containing gas or water vapor in the melt, the concentration of carbonaceous material in the melt and the rate of feed of the oxygen-containing gas into the medium.

Generally, the rate of carbon gasification increases as the temperature of the melt, the concentration of carbonaceous material, and the rate of oxygen-containing gas feed increase.

Preferably, the concentration of carbonaceous material in the melting medium is between 0.1 and
It is maintained at about 60% by weight, preferably from about 1.0 to about 20%, most preferably from about 1 to about 5% by weight, to provide rapid gasification of the carbonaceous material.

The gaseous products produced by contacting the carbonaceous material in the melting medium with an oxidizing gas, water vapor, or CO2 are in line 1.
1 from the gasification zone.

When water vapor is used as the gasifying agent, a hydrogen-rich gaseous effluent is produced and collected by line 11.

Contacting the carbonaceous material with water vapor at the temperature and pressure conditions preferred for the molten media regeneration of the present invention, typically at about 815.6°C (1500'F) and normal pressure, produces about 75 mole percent hydrogen and oxidized A gaseous effluent containing about 24 mole percent carbon is produced.

However, based on thermodynamic considerations, lower temperatures are preferred in the melting medium of the present invention, such as about 1000°F.
Gasifying carbonaceous material with steam at high pressure below should produce a gaseous effluent rich in methane.

Using steam as a gasifying agent produces a stream rich in hydrogen or methane, whereas using an oxygen-containing gas such as air as a gasifying agent produces a gaseous effluent rich in nitrogen.

It is believed that during gasification of carbonaceous material with an oxidizing gas such as air, sulfur impurities present in the carbonaceous material are oxidized to sulfur oxide and absorbed by the melting medium of the present invention.

Additionally, the process also serves to remove other contaminants present in heavy hydrocarbon feedstocks, such as ash-forming impurities, including trace metals such as vanadium, iron, and nickel, which are commonly present.

The melt regenerated as described above in gasification zone 8 is transferred to line 1
2 and reintroduced back into the decomposition zone 2.

Usually, the amount of carbonaceous material gasified in gasification zone 8 is:
Since it is substantially equal to the amount of carbonaceous material produced during the cracking operation in cracking zone 2, an overall balance of carbonaceous material is maintained in this system.

When an oxidizing gas such as air is used to gasify the carbonaceous material in gasification zone 8, sufficient heat is released to provide an overall thermal balance for both the gasification and cracking steps.

The continuous accumulation of sulfur and ash-forming impurities in the melt requires a slipstream from the integrated cracking and gasification steps described above to restore the levels of these impurities present in the melt to acceptable levels. ).

This side stream can be taken off from the cracking zone or the gasification zone or from the transfer line 7, 12, but it is preferably taken from the transfer line 7.

The reason why it is preferable to remove a portion of the contaminated melting media from the decomposition zone is that the decomposition zone contains a greater amount of carbonaceous material, which contains alkali or alkali metal sulfur oxides and metal sulfides. This is due to the fact that it acts to reduce the sulfur to sulfur, thereby facilitating the subsequent removal of the sulfur from the melting medium as described below.

As mentioned above, sulfur impurities present in carbonaceous materials are
The oxidizing gas stream is retained by the melting medium during gasification and is eluted from the coke by the melt at elevated temperatures.

However, when steam is used as the gasifying agent, the sulfur impurities are not converted to sulfur oxides or absorbed by the melt, and the sulfur in the carbonaceous material is mainly converted to hydrogen sulfide in the effluent from the gasification zone. will be collected.

Thus, when using an oxidizing gas stream as the gasifying agent, sulfur impurities are absorbed by the melt in the form of metal sulfites or sulfates.

The presence of carbonaceous material in the melting medium serves to reduce metal sulfites or sulfates, primarily alkali or alkali metal sulfites, to their sulfide form.

This metal sulfide is then fused with carbon dioxide and water,
Sulfur impurities are recovered as hydrogen sulfide.

Accordingly, a side stream 13 is removed from line 7 and sent to a sulfur recovery zone 14 where carbon dioxide and water vapor are introduced via line 15 and
The melt 16 is passed through at a temperature between 00 and 1800'F.

On the other hand, the melting medium containing sulfur impurities as metal sulfides is sent to the sulfur recovery zone, where it is brought into contact with water to dissolve the melt and collect precipitated metals and ash, and then carbon dioxide is bubbled into this solution to remove the sulfur. The impurities are recovered as a hydrogen sulfide rich stream.

In both embodiments, it is a requirement that the sulfur impurity be present in sulfide form before contacting the water or steam and carbon dioxide.

; if sufficient carbon chamber material is not present in the system, particularly in decomposition zone 2, to reduce the metal sulfates and sulfites to their sulfide form, the molten medium is reduced before being sent to sulfur recovery zone 16; It may be necessary to use a belt.

It is clear that when a reduction zone is required, side streams can be taken from any point in the system and then sent to the reduction zone where carbon, hydrogen, carbon monoxide, methane, ethane, etc. Metal sulfites or sulfates can be reduced to their sulfide form using suitable reducing agents.

When such a reduction zone is required, it is preferred to provide a retention zone below the decomposition zone in which substantially all of the metal sulfate or sulfite is effectively reduced to its sulfide form. The addition of additional amounts of carbon may or may not be necessary depending on the particular type of hydrocarbon feedstock.

In any case, the total sulfur concentration in the melting medium should be less than about 5.0% by weight, based on the total melting medium, preferably about 0.25-2.
It is preferable to maintain it below 0% by weight.

A hydrogen sulfide-enriched stream can be recovered from the sulfur recovery zone by line 17 and ultimately sent to a Claus unit for sulfur recovery.

The melting medium with reduced sulfur content is removed from the sulfur recovery zone by line 18 and this melting medium with reduced sulfur level is returned to the gasification zone by line 19.

Similarly, it is necessary to treat the melting medium to remove trace metals and ash that accumulate in the melt.

The melt stream with reduced sulfur content is therefore removed from line 18 by line 20 and sent to an ash recovery zone, not shown, where the ash is separated from the melt by dissolving it in water.

The invention will be further understood by the following examples.

Example 1 A heavy residual hydrocarbon feed containing materials with boiling points above 650° F. was pumped with 2036% by weight boron oxide B as the glass-forming oxide component (Experiment A).
) and 10% by weight (experiment B) into a stirred reactor containing a molten alkali metal carbonate medium consisting of 70 mol % lithium carbonate and 30 mol % sodium lagoon carbonate.

The decomposition zone is approximately 10.16 cr (4 inches) in diameter and approximately 3 inches long.
0.48 cr (12 inches) and placed in a Lindberg furnace.

Melt temperature is measured by a thermocouple inserted into a thermowell placed in the melting medium connected to a portable pyrometer.

The effluent gas is sent directly to a gas chromatograph for analysis.

The amount of C5+ liquid product and carbonaceous material, or coke, produced is also measured.

Table 1 Feedstock: 650°F+ Arabic heavy residual oil (2.3g/min) Melt: Li/with B203 in stirred reactor
Na (70/30 mol%) carbonate 1900 & Temperature: approx. 732.2~7608C (1350~140o
'F) Helium diluent: 1.2 to 1.517 minutes Heavy hydrocarbon resid feedstock in molten alkali carbonate medium containing 6% and 10% by weight boron oxide, as seen from the results in Table 1. Thermal decomposition of gives the 03-product at high conversion.

Example 2 This example describes how coke produced and dispersed during a cracking operation as outlined in Example 1 was heated to approximately 815.6°C (1500'F).
) shows the carbon gasification rate obtained by the present invention when contacted with air in a molten alkaline carbonate medium containing a glass-forming oxide, namely boron oxide.

Table 2 Coke gasification melt: 500 g of melt containing 1.9% by weight of coke Temperature: approx. 815.6°C (below 1500°C) Air flow rate: 2. OST Pl/min Pressure: Atmospheric Pressure As can be seen from the results in Table 2, the molten alkali metal carbonate medium containing a small amount of glass-forming oxides provides sufficient gasification of the coke present in the melt, so that the melt The melt can be easily regenerated after being used as a cracking medium for hydrocarbon feedstocks.

Example 3 A heavy residual hydrocarbon feedstock containing materials with a boiling point above 650° F. was agitated in the same manner as in Example 1 in a graphite lined bubble containing a melting medium. Introduced into the reactor.

The melting medium is 70 mol% lithium carbonate and 3 mol% sodium carbonate.
0 mol%, plus 2036% by weight of boron oxide B
has been added.

The hydrocarbon feedstock is introduced with a helium diluent (ISTPlZ min) and heated in this melting medium at about 732.2-760°C (
1350-1400' F.) for about 2.5 hours, during which time the carbonaceous material or coke produced during the cracking reaction is uniformly dispersed throughout the medium.

At the end of 2.5 hours, the melting medium contains approximately 3% by weight coke.

Example 4 A comparative heavy residual hydrocarbon feedstock is introduced into a bubble-shaped stainless steel stirred reactor containing a melting medium in the same manner as in Example 3.

The melting medium consists of 70 mol% lithium carbonate and 30 mol% sodium carbonate.

A hydrocarbon feedstock is introduced into this melting medium along with a helium diluent (ISTPl/min) and heated to about 732.2-760C (1
350-1400F) for about 40 minutes.

Since the carbonaceous material or coke produced during this cracking reaction is not dispersed as uniformly in the melting medium, the melting medium is
It forms layers, one of which is coke and the other relatively transparent.

At the end of this 40 minute cracking, the melting medium will contain approximately 0.0% coke.
Contains 5% by weight.

If the decomposition reaction is carried out for a further extended period of time, i.e. for 2 hours, the carbonaceous material becomes dispersed in a single homogeneous layer.

At the end of this 2 hour period, the melting medium contains approximately 2.0% coke by weight.

Example 5 This example shows the increase in desulfurization rate, as measured by steam conversion, when a molten alkali metal carbonate medium containing a small amount of boron oxide is contacted with steam and CO2 at a given temperature.

The conditions under which this experiment was conducted are shown in Table 3.

Table 3 Melt: Li2C03 70 mol% Na2cO3 30 mol% Sulfur concentration in melt: 4.8 wt% CO as sulfide
2/H20 feed ratio: 37/(63 mol%) As can be seen from the results shown in Figure 2, at a given temperature, when the sulfide-containing melting medium is brought into contact with water vapor and carbon dioxide, the The presence of boron oxide increases the desulfurization rate.

Example 6 This example demonstrates that a melting medium comprising an alkali metal carbonate in combination with a boron oxide is significantly less corrosive to containment material than a melting medium comprising a boron oxide in combination with an alkali oxide. show.

The following data were obtained by partially submerging refractory samples in a melting medium under the conditions shown in Table 4.

(9) As can be seen from the results in Table 4, the degree of corrosion of refractory materials is
It is directly related to the amount of boron oxide added to the melting medium.

Embodiments of the present invention and related matters are as follows.

(1) A renewable melting medium comprising an alkali metal carbonate containing a glass-forming oxide selected from the group consisting of boron, vanadium, silicon, and phosphorous oxides and mixtures thereof, and a hydrocarbon feedstock; 1. A process for cracking a hydrocarbon feedstock comprising contact at a temperature above the melting point of a hydrocarbon feedstock for a time sufficient to form a cracked hydrocarbon product.

(2) combining said raw material with a renewable melting medium comprising an alkali metal carbonate containing a glass-forming oxide selected from the group consisting of boron, vanadium, silicon, and phosphorus oxides, and mixtures thereof; Approximately 1 from melting point
contacting at a temperature in the range of 371.1° C. to form cracked hydrocarbon products and carbonaceous material, and then subjecting the melting medium containing the carbonaceous material to oxygen, water vapor, carbon dioxide,
gasifying a portion of the carbonaceous material produced during the decomposition step by contacting it with a reagent selected from the group consisting of: and mixtures thereof at a temperature ranging from about the melting point of the medium to about 1648.9°C; The method according to claim 1 or item (1) above, characterized in that:

(3) The temperature of the melting medium is approximately 648.9 to 1093.3C.
The method according to item (1) or (2) above, wherein the temperature is maintained within the range of .

(4) The amount of glass-forming oxides in the melting medium, expressed as oxides, is about 0.05% of the total melting medium. i ~ about 25% by weight
Claims or the above-mentioned items (1) to (3) are within the scope of
) The method described in any of the above.

(5) The method according to any one of claims or items (1) to (4) above, wherein the alkali metal carbonate is selected from the group consisting of lithium carbonate, sodium carbonate, and mixtures thereof.

(6) The method according to item (5) above, wherein the alkali metal carbonate is a mixture of a large amount of sodium carbonate and a small amount of lithium carbonate.

(7) The method according to any one of claims or (1) to (6) above, wherein the glass-forming oxide is an oxide of boron.

(8) The method according to any one of items (2) to (7) above, wherein the gasifying agent is oxygen.

(9) The method according to any one of claims or (1) to (8) above, wherein the melting medium contains an alkali metal borate.

00) The hydrocarbon feedstock contains sulfur and the amount of sulfur present in the melting medium is reduced by (a) contacting the sulfur compounds in the melting medium with a reducing agent, and (b) subsequent reduction produced in step (a). sulfur compounds which have been removed by contacting them with carbon dioxide and steam or water to form hydrogen sulfide as a recoverable product. the method of.

(11) The method according to item (10) above, wherein the reducing agent is carbon.

(12) At least a portion of the hydrocarbon feedstock is about 3
The above (1) or (1) which boils at 43.3°C or higher;
11) The method described in section 11).

[Brief explanation of the drawing]

FIG. 1 is a schematic flow diagram for pyrolyzing heavy hydrocarbon feedstocks in the melting medium of the present invention. FIG. 2 is a graph of the desulfurization rate in the melting medium.

Claims (1)

[Claims] 1. A hydrocarbon feedstock and a renewable melting medium comprising an alkali metal carbonate containing a glass-forming oxide selected from the group consisting of oxides of boron, vanadium, silicon and phosphorus and mixtures thereof; melting point of ~
A method of cracking a hydrocarbon feedstock comprising contacting at a temperature within the range of about 1371.1° C. for a sufficient time to form a cracked hydrocarbon product.