JPS5850278B2 - Nenryyou Gas Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing fuel gas from heavy oil, particularly vacuum residue oil.

Conventionally, a method of gasifying light hydrocarbons such as LPG and Natsuta by subjecting them to a catalytic steam cracking reaction is well known.

This usually uses a nickel oxide catalyst and has a
The process is carried out using an externally heated tubular reactor at a temperature of 0°C, but this method has limitations on the raw material hydrocarbons that can be treated, and in the case of heavy hydrocarbons with a high Conradson carbon value, the carbon on the catalyst is It is said that it cannot be used as a raw material because of severe precipitation.

These precipitated carbons are by-products during the thermal decomposition and gasification of hydrocarbons, and are converted into water gas by reacting with water vapor in the presence of a catalyst.

By the way, in the fixed bed catalytic steam cracking gasification method, since it is necessary to increase the packing porosity of the catalyst, the surface area of the catalyst per unit volume of the reactor inevitably becomes small. Carbonaceous substances such as tar are difficult to undergo water gasification, and if you try to process heavy oil with a high Conradson carbon value, the rate of precipitation of carbonaceous substances is greater than the rate of gasification, making continuous operation impossible. be.

One possible solution to the shortcomings of the fixed bed type catalytic steam cracking method is to perform catalytic cracking and gasification using a fluidized bed.

If a fluidized bed is used, the particle size of the catalyst particles can be reduced, and as a result, the surface area of the catalyst per unit volume of the reactor is increased, and as a result, it is possible to gasify a large amount of by-product carbonaceous matter.

An example of this method is a method in which an oxidizing gas (for example, air) is used as a fluidizing gas, and decomposition and gasification are performed by a partial combustion method.

This process involves partially combusting a fossil fuel with a stoichiometric amount of oxygen in a first fluidized bed of particles in the temperature range of 800-950°C containing particles consisting of oxidizing silium; into a flammable gas and bind substantially all of the sulfur in the fuel to the particles as a solid compound of calcium and sulfur, the flammable gas being fluidized by the gas and maintained below 600°C. passing through a second fluidized bed, thus condensing the tar in said gas onto the particles in the second bed, returning the condensed particles of tar from the second bed to the first bed, and partially oxidizing the combustible gas. It consists of converting into .

However, this method has the disadvantage that the amount of carbon dioxide in the combustible gas produced increases, and the amount of carbon dioxide in the gas excluding nitrogen gas reaches 22 to 30% by volume.

Therefore, recovery and gasification of tar by this method cannot be said to be a good means, and the by-produced tar must be gasified by a method that reduces carbon dioxide.

One method is to gasify the by-produced tar by a catalytic decomposition reaction with water vapor, instead of gasifying it by partial combustion.

In view of this situation, the present inventors have conducted intensive research on the gasification of heavy oil, especially vacuum residue oil, by fluid catalytic cracking.

As a result, the above-mentioned raw materials were supplied in the presence of an appropriate gasification catalyst at a temperature range of 850 to 900°C using a conventional one-unit fluidized bed or a two-unit particle circulation type fluidized bed to generate cracked gas. It has become clear that when this process is carried out, it is not possible to obtain sufficiently satisfactory results regarding the composition of the produced gas.

That is, for example, in a fluidized bed with forced circulation of catalyst particles, vacuum residue oil is used as a raw material, the temperature inside the fluidized bed of the reaction tower is set to 850 to 870°C, and one or more types selected from the group consisting of alkali metal compounds and alkaline earth metal compounds are used as a catalyst. Use a mixture of a substance and at least two substances from the group consisting of compounds of Groups I and II of the Periodic Table, and at least one transition metal compound, and use water vapor or water vapor and some oxygen. When attempting to obtain a relatively high-calorie fuel gas by decomposition gasification using a mixed gas with a mixture of It is high in heavy hydrocarbons and low in hydrogen and carbon monoxide, resulting in poor combustibility.
At the same time, a large amount of by-product carbonaceous substances such as carbon and tar precipitate, significantly interfering with the operation of the apparatus.

Therefore, the steam/raw material ratio inevitably increases, but as a result, the amount of carbon dioxide produced increases, similar to the above-mentioned partial combustion method, and the total calorific value of the produced fuel gas decreases.

The generated gas obtained in this way can be used to remove carbon dioxide and increase its calorific value using conventional absorption methods, but the removed carbon dioxide is directly discharged from the system, making it difficult to use energy effectively. This cannot be said to be preferable from this point of view.

Therefore, in order to eliminate such drawbacks, the present inventors have reduced the amount of steam used in the catalytic cracking gasification method using steam to a relatively small amount. The carbonaceous materials such as soot and tar that are produced as by-products are removed from the second part of the reaction column, which is located in the upper part of this fluidized bed.
A large amount of by-product carbon is deposited on the surface of the catalyst particles by guiding the bed to a stage fluidized bed and keeping it at a temperature far lower than the gasification reaction temperature.
The carbon dioxide removed from the log gas output from the first gasification reaction tower is reacted with this by-product carbonaceous substance to convert it into carbon monoxide, which is then transferred again to the first gasification reaction tower. C in this produced gas by incorporating it into the output log gas
Fuel gas production from heavy oil, especially vacuum residue oil, characterized by increasing the O/C02 ratio and returning the catalyst mainly by its own weight to the first gasification reaction tower or regeneration reaction tower for circulation use. The purpose is to provide a method.

At this time, if the device is equipped with a regeneration tower, the heat required for the reaction between the by-product carbonaceous and carbon dioxide can be obtained by indirectly guiding the outflow gas at the outlet of the regeneration tower to the fluidized bed in the second gasification reaction tower for heat exchange. This makes it possible to supply the retained heat of this outflow gas.

In addition, the CO2 removed from the log gas output from the first gasification reaction tower is indirectly introduced into the first stage fluidized bed in the first gasification reaction tower or into the space above the first stage fluidized bed, and the CO2 is converted into CO2 by heat exchange.
The gas may be fed to the fluidized bed in the second gasification reaction tower after increasing its retained heat.

In addition, in order to supply the heat necessary for the reaction in the second gasification reaction tower, an oxidizing gas (for example, air or oxygen) may be introduced into the fluidized bed in the second gasification reaction tower to burn part of the carbonaceous material. can.

Alternatively, at the same time, a part of the log gas output from the first gasification reaction column is transferred to the second
The reaction heat may be supplied by introducing the gas into a fluidized bed in the gasification reaction tower and burning the gas.

Furthermore, a transport bed or a moving bed may be used instead of the fluidized bed in the second stage reaction zone at the upper part of the first gasification reaction tower.

Further, the above catalyst has a particle size of 50 to 2000μ, and is a group consisting of one or more substances selected from the group consisting of alkaline earth metal compounds and alkali metal compounds, and compounds of Groups I and II of the Periodic Table. At least one substance among them and at least one transition metal compound are blended in appropriate proportions, mixed and granulated, and then fired at a high temperature in a kiln.

Using the present invention as a catalyst, calcium oxide and magnesium oxide are the main components, and acidic silicon and iron oxide are mixed therein so that the iron content is about 15% by weight of the total, and after mixing and granulation,
An example in which a product fired at a high temperature in a kiln is used will be described with reference to the drawings.

As shown in FIG. 1, the raw material heavy residual oil is introduced into the solid catalyst fluidized bed 5 in the first stage reaction zone 1 of the first gasification reaction tower together with steam introduced through the nozzle at the tip of the pipe 9, preferably through the pipe 29. Send.

A fluidizing gas, e.g. steam, is supplied from the bottom of the vessel by pipe 20 at a flow rate sufficient to fluidize the catalyst particles in the fluidized bed 5 and to properly gasify the feedstock.

The raw material fed into the first stage reaction zone 1 of the first gasification reaction tower undergoes catalytic gasification at a fluidized bed temperature of 850 to 950°C and a pressure above atmospheric pressure, and the produced gas is The reaction steam and by-produced carbonaceous substances such as soot and tar are entrained and become an upward flow, which flows into the solid catalyst fluidized bed 6 in the second stage reaction zone 2 separated by a constriction in the middle of the first gasification reaction tower.
becomes a fluidizing gas.

A heat exchanger tube 13 for heat exchange is installed in this fluidized bed 6, and a suitable cooling fluid, preferably high pressure water, is supplied to this heat exchanger tube 13 to maintain the temperature inside the fluidized bed 6 at 350 to 600°C. The coking reaction of the by-product carbonaceous material accompanying the gas from the first stage reaction zone 1 mainly takes place within this bed.

Further, if necessary, oxidizing gas or water vapor is fed through a pipe 31 provided at the bottom of the second stage reaction zone 2.

The generated decomposition gas exits from the pipe 23 and is transferred to the next step.

The catalyst fine particles scattered from the bed 6 along with the generated gas are the second
A gas-solid separator (not shown) provided above the stage reaction zone 2 (
For example, it is collected by a cyclone) and returned to the fluidized bed 6.

This gas-solid separator does not necessarily need to be located inside the reaction tower.

The generated coke adheres to the surface of the catalyst particles, and the coke-adhered particles are transferred to the pipe 18 connecting the upper part of the fluidized bed 6 in the second stage reaction zone 2 and the lower part of the fluidized bed 7 in the second gasification reaction tower 3.
It descends mainly due to its own weight and enters the second gasification reaction tower 3.

On the other hand, the generated cracked gas leaving the second stage reaction zone 2 of the first gasification reaction tower passes through the pipe 23 and enters the absorption tower 26, where the acidic gas in the cracked gas is selected by a conventionally known acid gas removal method. removed.

The carbon dioxide removed and recovered by this absorption tower is transferred to a pipe 32.
A fluidized bed 5 in the first stage reaction zone 1 of the first gasification reaction tower,
or the heat exchanger 1 installed in the fluidized bed upper space 33, or the fluidized bed 8 in the regeneration reaction tower 4, or the fluidized bed upper space 34.
2, the sensible heat of the gas is indirectly increased, and then the gas is fed from the bottom of the second gasification reaction tower 3 through the pipe 10,
The fluidized gas in the fluidized bed 7 in the second gasification reaction tower 3 is converted into carbon monoxide according to the reaction expressed by the following formula with the coke attached to the catalyst particles.

This carbon monoxide gas is introduced from the top of the second gasification reaction tower 3 through a pipe 25 into the cracked gas produced from the second stage reaction zone 2 of the first gasification reaction tower.

In addition, the amount of heat required for the reaction in the second gasification reaction tower 3 is determined by directing the outflow gas from the regeneration reaction tower 4 to the second gasification reaction tower 3 through a pipe 24.
The fluidized bed 7 is placed in the heat exchanger 14 provided in the fluidized bed 7 in the heat exchanger 14.
This is covered by sending the material under conditions that allow the internal temperature to be maintained at 850 to 950°C.

In addition, if necessary, a pipe 30 from the lower part of the second gasification reaction tower 3
An oxidizing gas (eg, air or oxygen) may be introduced by.

The catalyst particles in the second gasification reaction tower 3 enter the pipe 19 from a communication port provided at an appropriate position in the fluidized bed T, move downward in the pipe mainly due to their own weight, and are fluidized through the blowing port 16. A fluid (for example, water vapor) enters the fluidized bed 5 from the bottom of the first reaction zone 1 through a pipe 20 along with the flow thereof.

The catalyst particles that are involved in the reaction in the fluidized bed 5 and have an appropriate amount of coke on their surface enter the pipe 17 from a communication port installed at an appropriate position in the fluidized bed 5, and are transported downward in this pipe mainly due to their own weight. It enters the fluidized bed 8 from the bottom of the regeneration reaction tower 4 through the pipe 21 along with the flow of fluidizing fluid (for example, steam) fed from the inlet 15 at the bottom end of the pipe 17.

This fluidized bed 8 is composed of fluid from the bottom of the bed and regeneration reaction tower 4.
Oxidizing gas (e.g. air) sent from the lower tube 27
It is fluidized by.

Further, if necessary, steam may be introduced from the pipe 2B at the bottom of the regeneration reaction tower 4.

The oxidizing gas fed into the regeneration reaction zone 4 burns the coke attached to the surface of the catalyst particles, increasing the sensible heat possessed by the particles.

Furthermore, if necessary, fuel oil or fuel gas may be fed through a pipe 36 installed at the bottom of the fluidized bed 8 for combustion.

The catalyst particles whose activity has been restored and heated in the fluidized bed 8 are transferred to a downcomer pipe 22 provided at an appropriate position within the fluidized bed 8.
Fluid (e.g. water vapor) enters the pipe and moves downward mainly due to its own weight, and is fed from the air inlet 16 at the lowest end of the pipe 22.
Along with this, it is fed into the fluidized bed 5 from the bottom of the first stage reaction zone 1 of the first gasification reaction tower, and accelerates the gasification reaction while supplying the heat necessary for the gasification reaction.

FIG. 2 shows another embodiment of the present invention, in which the second stage reaction zone 2 of the first gasification reaction tower is not made into a fluidized bed as in the previous embodiment, but the liquid is dispersed from the first stage reaction zone 1. A transport layer is formed by catalyst fine particles, and the catalyst particles adhering to coke flowing out from the pipe 23 are separated from the accompanying gas in the gas-solid separator 3T, and then are dropped into the second gasification reaction tower 3. The rest is the same as in the previous embodiment, and the same parts as in the previous embodiment are given the same reference numerals.

FIG. 3 shows still another embodiment of the present invention, in which the heat necessary for the reaction in the first gasification reaction tower or the second gasification reaction tower is supplied without using a regeneration reaction tower. Fuel gas is produced by introducing an oxidizing gas (for example, air or hydrogen) in a proportion below the stoichiometric ratio to cause an exothermic reaction according to the following formula.

The oxidizing gas is introduced into the fluidized bed 5 in the first reaction zone 1 through a pipe 37.

Further, if necessary, it is introduced into the second reaction tower through a pipe 30, and the rest is the same as in the previous embodiment.

As an example of the present invention, Gatsuchisaran vacuum residue oil having the properties as shown in Table 1 is used as a raw material, and the gasification apparatus is of the same type as that shown in Fig. 1, and the inner diameter of the first reaction zone of the first gasification reaction tower is 41
．． 2im, second stage reaction zone inner diameter 65.9 dishes, reaction tower height 5
10mm, second gasification reaction tower inner diameter 41.2mm, height 22mm
Decomposition and gasification was carried out under the operating conditions shown in Table 2 using a laboratory apparatus having an inner diameter of 52.9 mm and a height of 400 mm.

Table-1 Properties of feedstock Name Gatsuchisaran Vacuum residue oil Conradone Carbon/wt% 21.4 Sulfur
wt% 3.65 Specific gravity a 25 L 03 Asphaltene content wt% 8.3 Metal content V ppm 492 Ni ppm 143 Table-2 1st stage reaction zone fluidized bed temperature 2nd stage reaction zone fluidized bed temperature 2nd gasification reaction Fluidized bed temperature in the column Regeneration Fluidized bed temperature in the reaction column Catalyst circulation rate Pressure (in the reaction column and regeneration column) H20/C molar ratio Raw material supply rate 880°C 450°C 880'C 905°C 15-30 ky/Hr Normal Pressure 2.5 0.13 kg/Hr As a result of this experiment, the cooled generated fuel gas had the following composition before entering the absorption tower.

It also has a calorie value of 5 i 75 kcal/Hm.

Vo1% H239,4 CO19,5 CO210,4 CH419,2 C2H410,3 C2H60,14 C3H60,10 c,, 0.56 H2S O,50 100,10 Also, as a comparative example, the second stage of the first gasification reaction tower reaction zone, second
Decomposition and gasification was carried out using the Gatsuchisaran vacuum residue oil shown in Table 1 as a raw material without using a gasification reaction tower and using the same conditions as shown in Table 2.

The generated gas was sampled and analyzed before entering the absorption tower and had the following composition, with a calorific value of 4588 kca and N
It was d.

Vo1% H241,7 CO9,4 CO220゜9 CH418,0 C2H48,6 C2H60,19 C30,08 C40,64 H2SO O,60 ioo,it From the above results, the method of the present invention has good flammability, It is clear that a fuel gas with reduced carbon dioxide content, which has a high calorific value, is obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the fuel gas production method of the present invention, and FIGS. 2 and 3 are schematic diagrams showing other embodiments of the present invention, respectively. 1... First stage reaction zone, 2... Second stage reaction zone, 3... Second gasification reaction tower, 4...
・Regeneration reaction tower, 5゜6...Solid catalyst fluidized bed, 7
,8...Fluidized bed, 9゜10...Tube, 1
2... Heat exchanger, 13... Heat exchanger tube, 1
4... Heat exchanger, 15... Inlet port, 1
6...Inlet, 17, 1B, 19, 20, 21
．． 22, 23° 24, 25... tube, 26...
...Absorption tower, 27, 2B. 29.30,31...tube, 33,34...
...Fluidized bed upper space, 36...Pipe, 37...
...gas-solid separator.

Claims (1)

[Claims] 1 In a method for producing fuel gas from heavy oil, especially vacuum residue oil, at a pressure higher than atmospheric pressure, the first
Feeding raw materials into a bed of catalyst particles containing an alkali metal compound or alkaline earth metal compound as a main component in a stage reaction zone, and fluidizing the particles by an upward flow of steam or a mixed gas of steam and oxidizing gas. The decomposition and gasification reaction is allowed to proceed in this fluidized reaction zone at a temperature range of 850 to 950°C, and the produced fuel gas and carbonaceous substances such as by-produced soot and tar are combined with the fluidized gas and these produced gases themselves. The by-product carbonaceous substances such as soot and tar pumped up from the first stage reaction zone are sent to the second stage reaction zone in the first gasification reaction tower by the rising force of 350%. ~6
forming coke on the surface of the catalyst particles in a temperature range of 00°C; sending the coke-adhered catalyst to a second gasification reaction tower; and producing gas exiting the second stage reaction zone in the second gasification reaction tower. reacting the carbon dioxide separated from the carbon dioxide with the coke-adhered catalyst at 840 to 970°C to convert the carbon dioxide into carbon monoxide, and converting this gas mainly consisting of carbon monoxide to the outlet of the first gasification reaction tower. A method for producing fuel gas comprising incorporating the catalyst into the produced gas and returning the catalyst leaving the second gasification reaction tower to the first reaction zone.