US20190316046A1

US20190316046A1 - Process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling

Info

Publication number: US20190316046A1
Application number: US16/386,851
Authority: US
Inventors: Yuanyu Tian; Yingyun Qiao; Jinhong Zhang; Jun Li; Yuanjun Che; Ruiyuan Tang
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2018-04-17
Filing date: 2019-04-17
Publication date: 2019-10-17
Also published as: CN108424785B; CN108424785A

Abstract

The invention provides a process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling, the process comprising: a high-efficiency atomizing nozzle sprays the preheated heavy oil into an upper portion of a downflow reaction tube, the produced oil mist mixes with a high temperature regenerated alkaline catalyst flowing downward from a dual-regulation return feeder, so as to heat, vaporize and crack the oil mist, the obtained stream containing a cracked oil and gas and an alkali catalyst to be generated flows rapidly and downward to the bottom of the downflow reaction tube to carry out a gas-solid separation; then the cracked oil and gas obtained from the gas-solid separation enters a fractionation column to be separated, the oil slurry obtained by separating the cracked oil and gas returns to mix with the heavy oil for recyclable use, while the other products separated from the cracked oil and gas are output as intermediate products; the alkali catalyst to be generated obtained from the gas-solid separation is subject to steam stripping and enters into a lower portion of a riser gasification reactor and carries out a catalytic gasification reaction with an oxidant and water vapor at a reaction temperature of 750° C. to 1,000° C., the subsequently generated material stream containing synthesis gas and regenerated alkaline catalyst flows rapidly and upward to a top of the riser gasification reactor to carry out a gas-solid separation; the high-temperature regenerated alkaline catalyst obtained from the gas-solid separation flows into the dual-regulation return feeder, wherein a portion of the high-temperature regenerated alkaline catalyst flows into the downflow reaction tube to continue to crack the heavy oil, the remaining portion of the high-temperature regenerated alkaline catalyst returns to the riser gasification reactor so as to continue the regeneration gasification; the synthesis gas obtained from the gas-solid separation is subject to a heat exchange and then output as a product.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The application claims priority to Chinese Application No. 201810341347.0, filed on Apr. 17, 2018, entitled “Process of Alkaline Catalytic Cracking of Inferior Heavy Oil with Double Reaction Tubes in Milliseconds and Gaseous Coupling”, which is specifically and entirely incorporated herein by reference.

FIELD OF THE INVENTION

The present invention provides a process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling, it pertains to the technical field of heavy oil processing.

BACKGROUND OF THE INVENTION

The conversion of heavy oil into light weight products is one of the important topics in petroleum processing industry in countries all over the world. Most of the crude oil in the People's Republic of China (PRC) has high content of residual oil and low content of light oil. In addition, given that China has continuously increased production of some heavy oil (thickened oil) and the importation of some heavy crude oil from foreign countries in recent years, the problem of converting the heavy oil into light weight products has become even more serious.
The methods of processing heavy oil generally comprise: catalytic cracking, solvent deasphalting, viscosity reduction, coking, thermal cracking, heavy oil hydrogenation, etc. In general, the methods may be classified into two major categories of hydrogenation and decarbonization, among which the decarburization of heavy oil is the main approach of petroleum refining at present, but the rational utilization of the removed carbon has not been desirably solved. The process of recycled cracking of heavy oil with solid phase carrier mainly includes catalytic cracking of heavy oil, flexible coking, fluid coking, heavy oil fluidization. In the process of catalytic cracking of heavy oil, it produces the target products (e.g., gasoline, diesel oil, and chemical raw material olefins), in addition, the removed residual carbon is burned in a regenerator for releasing heat, one part of the heat is applied as a heat source of cracking for the heated catalyst, and the other part is adopted by a heat extractor for producing steam which is delivered to the outside or be used for power generation; the catalytic cracking reaction temperature is low, which is about 500° C.-650° C., it imposes a high requirement on the content of residual carbon and heavy metals in the raw material heavy oil, so the inferior heavy oil can hardly meet the requirement. The flexible coking and fluidization coking of inferior heavy oil has a low reaction temperature, which is about 450° C.-600° C., it mainly produces coked gasoline, diesel, and coked wax oil used as catalytic raw material, part of the coke is burned for recycling as a heat carrier, and the other part is gasified to produce syngas; however, the cracking time is excessively long, and the yield of light oil is low. The inferior heavy oil fluidization (for example, the Asphalt Residual Treating (ART) process developed by Engelhard Corporation in the U.S.A, the Heavy-oil Contact Cracking (HCC) process developed by the Luoyang Petrochemical Design Institute in China, etc.) adopts a circulating fluidized bed technology similar to the heavy oil catalytic cracking process, the reaction temperature is about 400° C.-600° C., the cracking time is short, and the yield of light oil is high; however, its generalization and application are limited due to the excessive amount of residual carbon to be removed, and the difficulty in designing the external heat extraction.
Relative to the acidic catalyst (such as FCC molecular sieve catalyst, ZSM-5 molecular sieve catalyst), the alkaline catalyst is suitable for preparing olefins through the high temperature cracking, it is not deactivated by water vapor in high temperature, and it is beneficial to inhibiting coke formation and catalytic gasification of coke, thus the alkaline catalytic cracking of heavy oil becomes a hotspot in the researches on heavy oil pretreatment and processing heavy oil with chemical products dominated pattern.
In addition, due to the increasingly stringent requirements of environmental protection in China, the petroleum refining companies need a large amount of hydrogen to refine light oil products by hydrogenation thereby producing the qualified vehicle fuels; however, the various petroleum refinery enterprises lack a large number of cheap hydrogen sources currently.
It becomes a key issue to be urgently addressed by the petroleum practitioners in China concerning how to maximize utilization of heavy oil in the most economical, clean and reasonable manner and achieve a slag-free processing.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the existing heavy oil processing technologies, the purpose of the present invention is to develop a process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling, which can not only produce olefins and light oil with high yields, but also reduce the regeneration gasification reaction temperature and obtain a large amount of inexpensive hydrogen resources, and achieve the slag-free processing of heavy oil.
Specifically, the present invention provides a process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling, the process comprising:
1) a high-efficiency atomizing nozzle sprays the inferior heavy oil preheated to 180° C.-350° C. from a feed inlet of a downflow reaction tube into an upper portion of the downflow reaction tube, the produced oil mist mixes with a high temperature regenerated alkaline catalyst having a temperature ranging from 700° C.-950° C. flowing downward from a dual-regulation return feeder in milliseconds, so as to heat, vaporize and crack the oil mist, the cracking reaction temperature is within a range of 530° C.-850° C.; a stream containing a cracked oil and gas and a coked alkali catalyst to be generated is obtained, this stream flows rapidly and downward to a rapid gas-solid separator at the bottom of the downflow reaction tube to carry out a gas-solid separation to obtain the cracked oil and gas and the coked alkali catalyst to be generated respectively;
2A) the cracked oil and gas enters a fractionation column to be chilled and separated, thereby obtain a column bottom oil slurry and other products including gasoline, diesel oil, liquefied gas and cracked dry gas, respectively; the column bottom oil slurry returns to mix with the heavy oil for recyclable use, and the other products including gasoline, diesel oil, liquefied gas and cracked dry gas are output as intermediate products;
2B) the coked alkali catalyst to be generated is subject to steam stripping and then passes through a flow controller and enters into a lower portion of a riser gasification reactor to mix with an oxidant and water vapor to carry out a catalytic gasification regeneration reaction at a reaction temperature of 750° C. to 1,000° C., thereby generating a material stream containing synthesis gas and regenerated alkaline catalyst, this material stream flows rapidly and upward to a gas-solid separator on the top of the riser gasification reactor to carry out a gas-solid separation to obtain a high-temperature regenerated alkaline catalyst and a synthesis gas, respectively;
3A) the high-temperature regenerated alkaline catalyst flows into the dual-regulation return feeder such that a portion of the high-temperature regenerated alkaline catalyst with a catalyst/oil ratio of 3-12 flows into a top of the downflow reaction tube, thereby participating in the circulation and cracking of the heavy oil in the downflow reaction tube, and the remaining portion of the high-temperature regenerated alkaline catalyst passes through a recycle tube and returns to a lower portion of the riser gasification reactor so as to continue participation in the gasification regeneration reaction;
3B) the synthesis gas is subject to a heat exchange and then output as a product.
In step 2B) of the present invention, the coked alkali catalyst to be generated, water vapor and the oxidant are subject to a gasification and regeneration reaction in the riser gasification reactor at a temperature of 750° C. to 1,000° C., so as to produce a synthesis gas thereby preparing the hydrogen gas. The oxidant is one of oxygen, air, and oxygen-enriched air. The amount of the above-mentioned substances for preparing the synthesis gas may be selected according to the prior art, and the present invention does not repeat the unnecessary details.
In the present invention, the solid alkaline catalyst is one of calcium aluminate porous microsphere, magnesium aluminum spinel porous microsphere, calcium silicate porous microsphere, magnesium silicate porous microsphere, a porous carrier loaded with alkali metal or/and alkaline-earth metal or a mixture thereof, the particle size ranges from 5 μm to 300 μm, for example, from 10 μm to 300 μm.
In the present invention, the involved term “millisecond” refers to a time less than 600 ms. For example, the used term “millisecond mixing” refers to that the mixing time of the oil mist with the high-temperature regenerated alkaline catalyst having a temperature of 700° C. to 950° C. is less than 600 ms.
The term “catalyst/oil ratio” used in the invention refers to the weight ratio of the used amount of the regenerated alkaline catalyst to the used amount of the inferior heavy oil. In the case of a constant amount of the used heavy oil, when the numerical value of the “catalyst/oil ratio” is less than 3, it may result in an insufficient heat supply to the downflow reaction tube, the cracking reaction temperature is excessively low, and the oil mist cannot be completely cracked, it leads to a low yield of light oil; when the numerical value of the “catalyst/oil ratio” is greater than 12, it is prone to provide the downflow reaction tube with an excessive heat supply, the oil mist is excessively cracked, and the amount of pyrolysis dry gas is increased, it also may result in a decreased yield of the light oil.
In order to describe the present invention more expressly, the terms “rapid gas-solid separator” and “gas-solid separator” are used herein, their difference resides in that the rapid gas-solid separator has a separation time lower than the gas-solid separator, it is generally less than ⅓ of the separation time of the gas-solid separator.
The dual-regulation return feeder is not particularly limited in the present invention, it may refer to any return feeder which controls the flow rate of the regenerated alkaline catalyst such that a portion of the catalyst is delivered to the downflow reaction tube, and another portion of the catalyst is transported to the riser gasification reactor.
In the process of the present invention, the recycling and utilization process of the solid alkaline catalyst in the double reaction tubes comprises:
a) contacting a high-temperature alkaline catalyst with the heavy oil to crack the heavy oil in a downflow reaction tube, thereby producing low-carbon olefins and light oil products, and obtaining a coked alkali catalyst to be regenerated;
b) the coked alkali catalyst to be regenerated obtained in step a) is mixed with the oxidant and water vapor in the riser gasification reactor to carry out a gasification regeneration reaction, so as to obtain a high-temperature regenerated alkaline catalyst and a synthesis gas;
c) a portion of the high-temperature regenerated alkaline catalyst obtained in step b) returns to the downflow reaction tube to participate in the cracking reaction of the heavy oil; the remaining portion returns to the riser gasification reactor so as to continue participation in the preparation of the synthesis gas.
It can be seen from the following specific embodiments, as compared with an use of the acidic catalyst, the present invention utilizes a high-temperature alkaline catalyst to contact with the heavy oil having a residual carbon content of 20% in the downflow reaction tube in milliseconds, such that the heavy oil is cracked to produce olefins and light oil, the yield of olefins increases by 10%-30% and the yield of light oil improves by 14 percentage point; the coked alkali catalyst, water vapor and the oxidant carry out a gasification regeneration reaction in the riser gasification reactor to generate a synthesis gas for preparing the hydrogen gas, wherein the water vapor is gasified, which can be utilized for heat absorption, so as to solve the difficult problem that the heat regenerated by the alkaline catalyst is excessive. In the examples, the yield of hydrogen gas is not less than 250 Nm³when the oxygen is used as the oxidant. The present invention allows that the cost of hydrogen gas of the refinery enterprises is significantly decreased (by about 70%), the gasification intensity is large, the equipment volume is small, the steel consumption is low, and the fixed investment is greatly reduced; in addition, during the process of the present invention, the atmospheric pressure operation is simple, it is convenient to start or shut down the apparatus, the operational continuity is desirable, and the apparatus has strong adaptability for processing a variety of oils; the petroleum resources are fully and effectively utilized, and the slag-free processing of heavy oil is performed with low energy consumption.
Furthermore, the process of the present invention allows a double cycle treatment of the regenerated alkaline catalyst (double cycle means that a portion of the regenerated alkaline catalyst returns to the downflow reaction tube for cracking the heavy oil, and the other portion of the regenerated alkaline catalyst returns to the riser gasification reactor for producing the synthesis gas), such that the entire process may be continuously operated on a long-term basis, thereby effectively improving the production efficiency. Based on the practical requirements on the yield of hydrogen gas and the yield of target products, it is not required by the process of the present invention to adjust the operating conditions of each step of the entire apparatus, but only performing adjustment and control on two aspects, namely the gasification temperature in the riser and the catalystloil ratio in the downflow reaction tube; as a result, the coke gasification rate and the regeneration degree of the catalyst in the riser gasification reactor are not completely dependent on the amount and the rate of generated coke produced from cracking of heavy oil in the downflow reaction tube, the operational flexibility of the apparatus in the invention is greatly enhanced. For example, as shown in Example 1, during the stable operation of the apparatus in the present invention, if the apparatus operator intends to increase the yield of hydrogen gas (while ensuring the yields of olefins and the light oil to be substantially constant), it can be realized by lowering the gasification regeneration temperature, raising the catalyst/oil ratio in the cracking of heavy oil, and increasing the recycle ratio of the regenerated alkaline catalyst in the riser gasification reactor; if the apparatus operator wants to increase the yield of olefins and the light oil (while ensuring the yield of hydrogen gas to be substantially constant), it may be fulfilled by lowering the catalyst/oil ratio in the cracking of heavy oil, and raising the cracking temperature.
The technological characteristics of the present invention will be described below in detail with reference to FIG. 1 and the examples.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a technological process in the present invention.

DESCRIPTION OF THE REFERENCE SIGNS

1. gas-solid separator;
2. dual-regulation return feeder;
3. high-efficiency atomizing nozzle;
4. downflow reaction tube:
5. rapid gas-solid separator;
6. cracked gas outlet;
7. flow controller;
8. steam inlet;
9. oxidant inlet;
10. riser gasification reactor;
11. heat exchanger;
12. synthesis gas outlet;
13. recycle tube;
14. fractionation column.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Each of the following examples illustrates the process of the present invention by referring to FIG. 1.
The flow diagram shown in FIG. 1 comprises the following steps:
1) a high-efficiency atomizing nozzle 3 sprays the inferior heavy oil preheated to 180° C.-350° C. from a feed inlet of a downflow reaction tube 4 into an upper portion of the downflow reaction tube 4, the produced oil mist mixes with a regenerated alkaline catalyst having a temperature ranging from 700° C.-950° C. flowing downward from a dual-regulation return feeder 2 in milliseconds, so as to heat, vaporize and crack the oil mist, the cracking reaction temperature is within a range of 530° C.-850° C.; a stream containing a cracked oil and gas and a coked alkali catalyst to be generated is obtained, this stream flows rapidly and downward to a rapid gas-solid separator 5 at the bottom of the downflow reaction tube 4 to carry out a gas-solid separation to obtain the cracked oil and gas and the coked alkali catalyst to be generated respectively;
2A) the cracked oil and gas derived from step 1) passes through a cracked gas outlet 6 and enters a fractionation column 14 to be chilled and separated, thereby obtain a column bottom oil slurry and other products such as gasoline, diesel oil, liquefied gas and cracked dry gas, respectively; the column bottom oil slurry returns to mix with the heavy oil for recyclable use, and the other products, i.e. gasoline, diesel oil, liquefied gas and cracked dry gas, are output as intermediate products;
2B) the coked alkali catalyst to be generated derived from step 1) is subject to steam stripping and then passes through a flow controller 7 and enters into a lower portion of a riser gasification reactor 10 to mix with an oxidant introduced through an oxidant inlet 9 and water vapor introduced through a steam inlet 8 to carry out a gasification reaction at a reaction temperature of 750° C. to 1,000° C., thereby generating a material stream containing synthesis gas and regenerated alkaline catalyst, this material stream flows rapidly and upward to a gas-solid separator 1 on the top of the riser gasification reactor 10 to carry out a gas-solid separation to obtain a high-temperature regenerated alkaline catalyst and a synthesis gas, respectively;
3A) the high-temperature regenerated alkaline catalyst derived from step 2B) flows into the dual-regulation return feeder 2 such that a portion of the high-temperature regenerated alkaline catalyst with a catalyst/oil ratio of 3-12 flows into a top of the downflow reaction tube 4, thereby participating in the circulation and cracking of the heavy oil in the downflow reaction tube, and the remaining portion of the high-temperature regenerated alkaline catalyst passes through a recycle tube 13 and returns to a lower portion of the riser gasification reactor 10 so as to continue participation in the gasification regeneration reaction;
3B) the synthesis gas derived from step 2B) is subject to a heat exchange with a heat exchanger 11 and then output as a product through a synthesis gas outlet 12.
The key property parameters of the inferior heavy oil processed in the following examples and comparative examples are shown in Table 1:

	TABLE 1

	Density (kg/m³, 20° C.)	1,038
	Viscosity (mm · s⁻¹, 100° C.)	520
	Residual carbon content (wt %)	20
	Carbon content (wt %)	85.8
	Hydrogen content (wt %)	6.9

The yield of olefins refers to the total yield of three olefins (i.e., ethylene, propylene and butene) derived from cracked dry gas.
The yield of light oil refers to the total yield of liquefied gas, gasoline and diesel oil.
The yield of hydrogen gas: the yield of hydrogen in the synthesis gas produced by per ton of heavy oil during the gasification regeneration process in the technological process.

EXAMPLE 1

The alkaline catalyst used in the example is a calcium silicate porous microsphere having a particle size ranging from 15-150 μm.
The technological process is as follows:
1) a high-efficiency atomizing nozzle 3 sprays the inferior heavy oil preheated to 200° C. from a feed inlet of a downflow reaction tube 4 into an upper portion of the downflow reaction tube 4, the produced oil mist mixes with a regenerated alkaline catalyst having a temperature of 800° C. flowing downward from a dual-regulation return feeder 2 in milliseconds, so as to heat, vaporize and crack the oil mist, the cracking reaction temperature is 580° C.; a stream containing a cracked oil and gas and a coked alkali catalyst to be generated flows rapidly and downward to a rapid gas-solid separator 5 at the bottom of the downflow reaction tube 4 to carry out a gas-solid separation;
2A) the cracked oil and gas derived from step 1) passes through a cracked gas outlet 6 and enters a fractionation column 14 to be chilled and separated, the obtained column bottom oil slurry returns to mix with the heavy oil for recyclable use, and the other products, i.e. gasoline, diesel oil, liquefied gas and cracked dry gas, are output as intermediate products;
2B) the coked alkali catalyst to be generated derived from step 1) is subject to steam stripping and then passes through a flow controller 7 and enters into a lower portion of a riser gasification reactor 10 to mix with an oxidant introduced through an oxidant inlet 9 and water vapor introduced through a steam inlet 8 to carry out a gasification reaction at a reaction temperature of 870° C., thereby generating a material stream containing synthesis gas and regenerated alkaline catalyst, this material stream flows rapidly and upward to a gas-solid separator 1 on the top of the riser gasification reactor 10 to carry out a gas-solid separation;
3A) the high-temperature regenerated alkaline catalyst derived from step 2B) flows into the dual-regulation return feeder 2 such that a portion of the high-temperature regenerated alkaline catalyst with a catalyst/oil ratio of 6 flows into a top of the downflow reaction tube 4, thereby participating in the circulation and cracking of the heavy oil in the downflow reaction tube, and the remaining portion of the high-temperature regenerated alkaline catalyst passes through a recycle tube 13 and returns to a lower portion of the riser gasification reactor 10 so as to continue participation in the gasification regeneration reaction;
3B) the synthesis gas derived from step 2B) is subject to a heat exchange with a heat exchanger 11 and then output as a product through a synthesis gas outlet 12.
The result shows that the yield of olefins is 30%, the yield of light oil is 87%, and the yield of hydrogen gas is 250 Nm³.
During the operation of the apparatus, if the gasification regeneration temperature is lowered from 870° C. to 800° C., while the catalyst/oil ratio during the cracking of heavy oil is increased from 6 to 7.9, and the cycle ratio of the high-temperature regenerated alkaline catalyst in the riser gasification reactor is hiked, the yields of the obtained olefins and light oil are almost unchanged, and the yield of hydrogen gas is increased to 280 Nm³in this case;
During the operation of the apparatus, if the catalyst/oil ratio during the cracking of heavy oil is raised from 6 to 6.8, the cracking temperature is increased from 580° C. to 610° C., and the gasification regeneration operating conditions may be kept substantially unchanged. In this case, the yield of olefins and the yield of light oil increase by 0.5 percentage point respectively, while the yield of hydrogen gas is basically unchanged.
As can be seen from the above Example 1 that the process of the present invention may adopt various control means according to the required yields of olefins and light oil and the desirable yield of hydrogen gas, and it is convenient to perform a flexible adjustment and control.

EXAMPLE 2

The process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling is performed in accordance with Example 1, except that the gas entering the oxidant inlet 9 is changed from the oxygen to the oxygen-enriched air having an oxygen content of 35 volume %.
The result shows that the yield of olefins is 30%, the yield of light oil is 87%, and the yield of hydrogen gas is 220 Nm³.

EXAMPLE 3

The process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling is performed in accordance with Example 1, except that the gas entering the oxidant inlet 9 is changed from the oxygen to the air.
The result shows that the yield of olefins is 30%, the yield of light oil is 87%, and the yield of hydrogen gas is 190 Nm³.

COMPARATIVE EXAMPLE 1

The process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling is performed in accordance with Example 1, except that the catalyst used in the comparative example is acidic alumina microspheres having a particle size range of 15-150 μm.
The result shows that the yield of olefins is 20%, the yield of light oil is 73%, and the yield of hydrogen gas is 450 Nm³.

COMPARATIVE EXAMPLE 2

The alkaline catalyst used in this comparative example is a calcium silicate porous microsphere having a particle size range of 15-150 μm.
1) a high-efficiency atomizing nozzle sprays the inferior heavy oil preheated to 200° C. from a feed inlet of a downflow reaction tube into an upper portion of the downflow reaction tube, the produced oil mist mixes with a regenerated alkaline catalyst having a temperature of 800° C. flowing downward from a return feeder in milliseconds, so as to heat, vaporize and crack the oil mist, the cracking reaction temperature is 580° C.; a stream containing a cracked oil and gas and a coked alkali catalyst to be generated flows rapidly and downward to a rapid gas-solid separator at the bottom of the downflow reaction tube to carry out a gas-solid separation;
2A) the cracked oil and gas derived from step 1) passes through a cracked gas outlet and enters a fractionation column to be chilled and separated, the obtained column bottom oil slurry returns and mixes with the heavy oil for recyclable use, and the other products, i.e. gasoline, diesel oil, liquefied gas and cracked dry gas, are output as intermediate products;
2B) the coked alkali catalyst to be generated derived from step 1) is subject to steam stripping and then passes through a flow controller and enters into a lower portion of a riser gasification reactor to mix with an oxidant introduced through an oxidant inlet and water vapor introduced through a steam inlet to carry out a gasification reaction at a reaction temperature of 870° C., the generated material stream containing synthesis gas and regenerated alkaline catalyst flows rapidly and upward to a gas-solid separator on the top of the riser gasification reactor to carry out a gas-solid separation;
3A) all the high-temperature regenerated alkaline catalyst derived from step 2B) passes through the return feeder to flow into a top of the downflow reaction tube, thereby participating in the circulation and cracking of the heavy oil;
3B) the synthesis gas derived from step 2B) is subject to a heat exchange with a heat exchanger 11 and then output as a product through a synthesis gas outlet 12.
The result shows that the yield of olefins is 30%, the yield of light oil is 87%, and the yield of hydrogen gas is 250 Nm³.
With respect to a given raw material heavy oil in the comparative example, in order to ensure the above-mentioned yields of the olefins, light oil and hydrogen gas, the reaction temperatures and the recycle ratio of catalyst in each part must be strictly maintained during the operation of the apparatus following an establishment of the balance between the catalytic cracking reaction and the catalyst regeneration reaction, otherwise it will easily lead to unstable operation of the apparatus, or even cause a temperature runaway phenomenon. For example, in order to increase the yield of olefins, the cracking temperature may be raised to 610° C., the ratio of water vapor/oxidant must be adjusted to lower the yield of hydrogen gas, thus it is required to re-adjust the operating conditions of the entire apparatus.
Therefore, the process in the comparative example has extremely high requirements on the manipulation and control, and the apparatus has poor manipulation flexibility, thus the yields of hydrogen gas, olefins and light oil cannot be effectively adjusted and controlled.
As can be seen from a comparison between Example 1 and Comparative Example 2, Example 1 has preferable manipulation flexibility, and the catalystloil ratio and the cracking temperature during the cracking process of heavy oil are not completely confined by the gasification regeneration temperature, and it can also achieve higher target product yields and increase production efficiency.

Claims

1. A process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling, wherein the process comprising:

1) a high-efficiency atomizing nozzle sprays the inferior heavy oil preheated to 180° C.-350° C. from a feed inlet of a downflow reaction tube into an upper portion of the downflow reaction tube, the produced oil mist mixes with a high temperature regenerated alkaline catalyst having a temperature ranging from 700° C.-950° C. flowing downward from a dual-regulation return feeder in milliseconds, so as to heat, vaporize and crack the oil mist, the cracking reaction temperature is within a range of 530° C.-850° C.; a stream containing a cracked oil and gas and a coked alkali catalyst to be generated is obtained, this stream flows rapidly and downward to a rapid gas-solid separator at the bottom of the downflow reaction tube to carry out a gas-solid separation to obtain the cracked oil and gas and the coked alkali catalyst to be generated respectively;

2A) the cracked oil and gas enters a fractionation column to be chilled and separated, thereby obtain a column bottom oil slurry and other products including gasoline, diesel oil, liquefied gas and cracked dry gas, respectively; the column bottom oil slurry returns to mix with the heavy oil for recyclable use, and the other products including gasoline, diesel oil, liquefied gas and cracked dry gas are output as intermediate products;

2B) the coked alkali catalyst to be generated is subject to steam stripping and then passes through a flow controller and enters into a lower portion of a riser gasification reactor to mix with an oxidant and water vapor to carry out a catalytic gasification regeneration reaction at a reaction temperature of 750° C. to 1,000° C., thereby generating a material stream containing synthesis gas and regenerated alkaline catalyst, this material stream flows rapidly and upward to a gas-solid separator on the top of the riser gasification reactor to carry out a gas-solid separation to obtain a high-temperature regenerated alkaline catalyst and a synthesis gas, respectively;

3A) the high-temperature regenerated alkaline catalyst flows into the dual-regulation return feeder such that a portion of the high-temperature regenerated alkaline catalyst with a catalyst/oil ratio of 3-12 flows into a top of the downflow reaction tube, thereby participating in the circulation and cracking of the heavy oil in the downflow reaction tube, and the remaining portion of the high-temperature regenerated alkaline catalyst passes through a recycle tube and returns to a lower portion of the riser gasification reactor so as to continue participation in the gasification regeneration reaction;

3B) the synthesis gas is subject to a heat exchange and then output as a product.

2. The process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling according to claim 1 wherein the oxidant is one of oxygen, air, and oxygen-enriched air.

3. The process of alkaline catalytic cracking of inferior heavy oil with double reaction tubes in milliseconds and gaseous coupling according to claim 1, wherein the alkaline catalyst is one of calcium aluminate porous microsphere, magnesium aluminum spinel porous microsphere, calcium silicate porous microsphere, magnesium silicate porous microsphere, a porous carrier loaded with alkali metal or/and alkaline-earth metal or a mixture thereof, the particle size ranges from 5 μm to 300 μm.