Catalytic cracking reaction-regeneration system

A catalytic cracking reaction-regeneration system, comprising a regenerator, a settler, a gas-solid separator, a buffer, a riser reactor, a horizontal reaction tube, a catalyst delivery pipe, and a down-flow reactor. This system can be used for experiments and researches on various processes such as riser catalytic cracking, sectional feeding, instantaneous contact, and down-flow catalytic cracking and can be used for catalyst evaluation tests. This abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to catalytic cracking apparatus of petroleum hydrocarbons in the absence of hydrogen and, more particularly, to a catalytic cracking reaction-regeneration system for the application in laboratories.

2. Description of Background and Related Art

Catalytic cracking is an important refining process for producing motor fuel oils and chemical feedstocks and is an effective means for lightening heavy oils. Therefore, catalytic cracking process has been a researching point of studies in the refinery industry for decades. As known to all, the development of a novel process and catalyst must under go a rather long investigation course from bench-scale exploration, via pilot plant, to industrial application. Therefore, whether the data in laboratories are prospective, in other words, whether said data are able to reflect the anticipated results of the industrial application is a key to the success of the technical development. There are two ways for researching catalytic cracking processes in laboratories: one is to use a fixed fluidized-bed unit, and the other is to use a continuous reaction-regeneration fluidized-bed unit or a riser unit. The fixed fluidized-bed unit is small in scale, convenient, flexible, cheap, and with the use of a small amount of oil and catalyst; so, it is widely adopted by many research institutes and refineries mainly for evaluating catalysts. Small or medium units for continuous reaction-regeneration unit can better simulate the conditions in an industry-scale unit and match the industrial data in the yield and the quality of the resultant products.

There are not many reference documents in the prior art concerning laboratory catalytic cracking units. The relevant information can be referred to U.S. Pat. No. 6,069,012 and the circulating riser catalytic cracking experimental unit of GRACE DAVISON CORPORATION. However, the function of these units is rather simple and cannot meet the needs of the evaluation of various novel catalysts and the development of the processing.

U.S. Pat. No. 6,069,012 discloses an improved fixed fluidized-bed reactor. The improvement in the structure of this reactor is embodied in the following two aspects: (1) adoption of a height-variable feeding sleeving, the inner tube of which is used to deliver oil feedstocks, while the jacket is used to deliver the fluidizing gas; and (2) a fluidizing gas nozzle is additionally equipped at the center of the bottom of the reactor. The above improvements in the structure enable the fixed fluidized-bed reactor to adjust the reaction time by modifying the height of the feeding nozzle. Besides, the addition of the fluidizing gas nozzle at the bottom of the reactor can improve the fluidized state of the catalyst; however when the linear speed of the reactor bed is equal to or greater than 18.2 cm/sec, a violent turbulent flow and slugging may happen to the catalyst bed, the catalyst may be elevated to the top of the reactor and deviated from the isothermal section of the reactor, which leads to ineffective control of the reaction temperature. Because of the limitation of the above bed linear speed, such a reactor can only be experimented under ordinary catalytic cracking reaction conditions, but is not suitable for the special reaction requirements of the present catalytic cracking field for carrying out reaction under high temperature, high catalyst/oil ratios, high gas outputs, and so on.

One of the most important process parameters of fluidized catalytic cracking is the contact time of hydrocarbons and the catalyst. Recent studies show that 90% of the feedstock conversion takes place during a very short time of the feedstock contacting with the catalyst. Based on this knowledge, the structure of existing units is gradually reformed to raise the yield and quality of the product. However, a shorter feedstock-oil contact time needs the match of a higher catalyst/oil ratio to achieve a desirable conversion depth of hydrocarbons and oil. Therefore, either the design of a new unit, or the reformation of an old unit should meet the requirement in this respect.

In a continuous reaction-regeneration system, the shortening of the reaction time can be realized by using a down-flow reactor or instantaneous reaction structure with ultrashort time. In addition to a short oil/catalyst contact time, down-flow reactor can greatly reduce backmixing and thereby reduce the secondary reactions which are unfavorable to the product distribution. The instantaneous reaction structure can examine the positive influence of the ultrashort reaction time on the distribution and quality of the product.

As for the present continuous reaction-regeneration experimental units for catalytic cracking both at home and abroad, no reports have been found relating to the integration of riser, down-flow operation, and instantaneous reaction structure which results in flexible switch their-between.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a novel laboratory-scale catalytic cracking unit, which can not only be used for evaluating catalyst performance, but also meet the requirement for research on a variety of catalytic cracking processes.

a catalytic cracking reaction-regeneration system, characterized in that said system comprises:

a regenerator1used for regenerating the coke-deposited spent catalyst, a flue gas pipe being equipped at the top of said regenerator, and a regeneration air pipe and a regeneration catalyst delivery pipe2being equipped at the bottom;

a settler15, its upper section being used for the convergence and disengagement of the reaction oil-gas, the lower section being used for stripping the coke-deposited catalyst, the top of the settler being equipped with an oil-gas pipe which is connected to a separation system, and the bottom of said settler being connected with regenerator1via a spent catalyst delivery pipe18;

a gas-solid separator14used for separating the reaction oil-gas and the catalyst, the top of said gas-solid separator being connected with the upper section of settler15via a pipeline, and the bottom of said separator being connected with the lower section of settler15;

a buffer9used for storing the catalyst when the system carries out down-flow reaction;

a riser reactor5used to carry out riser catalytic cracking reaction, the lower section of said riser reactor being connected with regenerator1via regenerated catalyst delivery pipe2;

a horizontal reaction pipe13used to carry out instantaneous contact catalytic cracking reaction, one section of said horizontal reaction pipe being vertically connected with the outlet of the upper section of riser reactor5via valve A, while the other section being connected with the inlet of gas-solid separator14;

a catalyst delivery pipe8connecting the riser reactor with the buffer tank, said delivery pipe is coaxial with riser reactor5, locates above it, and is used for delivering the catalyst from riser5and the elevating medium, then introducing them into buffer tank9, valve C being equipped between catalyst delivery pipe8and riser reactor5; and

a down-flow reactor12used for carrying out down-flow catalytic cracking reaction, the upper section of said down-flow reactor being connected with the buffer tank, and the lower section being connected with a horizontal reaction pipe13via valve B or being connected with settler15.

Compared to the prior art, the useful effects of the present invention are mainly embodied in the following aspects:

The catalytic cracking-regeneration system of the present invention integrates the structural features of riser, down-flow reaction and instantaneous reaction, and can meet the needs of the experiments and researches on a variety of processes and create convenient conditions for studies and development of the catalytic cracking process.

The catalytic cracking-regeneration system of the present invention can be used for the catalytic cracking experiment on different oil feedstocks and catalysts, and thereby can yield representative experimental data. These experimental results can provide both basis for the design of industrial units and data for the development of the mathematic model of catalytic cracking.

The present application claims priority under 35 U.S.C. §119 of Chinese Patent Application No. 01140184.2 filed on Nov. 29, 2001. The disclosure of the foregoing application is expressly incorporated by reference herein in its entirety.

DETAILED DESCRIPTION OF THE INVENTION

In the catalytic cracking-regeneration system according to the present invention, the top of regenerator1is equipped with a flue gas pipe and the bottom of it is equipped with a regeneration air pipe and a regeneration catalyst delivery pipe2installed with regeneration slide valve3. Settler15is used for the convergence and disengagement of the reaction oil-gas, the lower part of which being used for stripping the coke-deposited spent catalyst. The top of said settler is equipped with an oil-gas pipe connected to the separation system, while the bottom of it is connected with regenerator1via spent catalyst delivery line18having a regeneration slide valve17. Buffer tank9is used for storing the catalyst in the down-flow reaction of the system. At the top of said buffer tank, a venting pipe is set; and at its bottom, there is buffer slide valve10. Catalyst delivery pipe8, connecting the riser reactor with the buffer tank, is coaxial with riser reactor5and located above said reactor, for delivering the catalyst from riser5and the elevating medium and then introducing said materials into buffer tank9. Valve C is set between catalyst delivery pipe8and riser reactor5. Down-flow reactor12is used for carrying out down-flow catalytic cracking reaction, the upper section of reactor12is connected to buffer slide valve10while the lower section of it is connected to horizontal reaction pipe13or to the settler via valve B. The down-flow reactor should be in such a way that the catalyst in the buffer tank enters into the down-flow reactor via the buffer slide valve and under the action of gravity.

In the catalytic cracking-regeneration system according to the present invention, said gas-solid separator is selected from cyclone separator, filtration tube, filter screen and other means suitable for separating hydrocarbon gases and the catalyst, with cyclone separator or filtration tube being preferred.

In the catalytic cracking-regeneration system according to the present invention, the internal part of the down-flow reactor12can be equipped with various types of baffles or packing for improving the contact condition of the petroleum hydrocarbon and the catalyst in the down-flow reactor and for effectively controlling the contact time of the two.

In the catalytic cracking reaction regeneration system of the present invention, gas-solid separator14may locate either outside or inside of settler15. Said valves A, B and C are any one selected from the member consisting of baffle, manual ball valve, pneumatic ball valve, or plugging screw, and baffle is preferred.

In the catalytic cracking reaction-regeneration system of the present invention, the upper section and the lower section of riser reactor5are equipped with feeding nozzles7and4respectively, while feeding nozzle6is installed between nozzles7and4. The relative positions of above nozzles can be adjusted according to the requirement of the experiment. The upper section of said down-flow reactor12is equipped with feeding nozzle11which can either be vertical to the down-flow reactor or situated in other angles.

The present invention has no special requirement for the relative position between the regenerator and the settler, and the former can locate either above or below the latter. The outlet, of the spent catalyst delivery pipe connected with the settler and the regenerator which locates at one side of the regenerator, can be equipped either above or below the catalyst dense phase bed of the regenerator.

The operation way of the catalytic cracking reaction-regeneration system of the present invention will be further illustrated in combination with the FIGURE, but is not limited here to.

1. Carrying out riser catalytic cracking reaction by closing valves B and C and opening valve A.

As shown inFIG. 1, the oil feedstock enters riser reactor5via nozzle4, uniformly mixes at the inlet of the riser reactor with the regenerated catalyst from regenerated catalyst delivery pipe2, rapidly evaporates and reacts. The mixture of oil-gas and the catalyst ascends along the riser and enters gas-solid separator14via horizontal reaction pipe13. Under the action of the gas-solid separator, oil-gas is rapidly separated from the catalyst to reduce the secondary cracking reaction of the products. The spent catalyst falls down to the stripping section at the lower part of settler15via the dipleg, and the reaction oil-gas enters the top of the settler via the uptake, after filtering off fine powders, leaves the top, and enters the subsequent separation system.

The spent catalyst in stripping section of the settler is stripped. The stripped catalyst is fed to regenerator1via spent catalyst delivery pipe18equipped with spent catalyst slide valve17. The spent catalyst is regenerated by burning off coke in the regenerator and the regenerated catalyst is fed to the riser reactor via regenerated catalyst delivery pipe2equipped with regenerated catalyst slide valve3for recycling use. The regenerated flue gas leaves the top of the regenerator after filtration.

2. Carrying out sectionally feeding experiment in the riser by closing valves B and C and opening valve A.

As shown inFIG. 1, a part of the oil feedstock enters riser5via nozzle4, uniformly mixes at the inlet of the riser reactor with the regenerated catalyst from the regenerated catalyst delivery pipe2, rapidly evaporates and reacts; meanwhile, the remaining part of the oil feedstock enters the riser via nozzle6, and contacts and reacts with the catalyst and oil-gas flowing upwards from the bottom of the riser. The mixture of the reaction oil-gas and the catalyst enters gas-solid separator14via horizontal reaction pipe13. The spent catalyst falls down to the stripping section at the lower part of settler15via the dipleg, and the reaction oil-gas enters the top of the settler via the uptake, then leaves the top after filtering off fine powders, and enters the subsequent separation system.

The spent catalyst in stripping section of the settler is stripped. The stripped catalyst is fed to regenerator1via spent catalyst delivery pipe18equipped with spent catalyst slide valve17. The spent catalyst is regenerated by burning off coke in the regenerator and the regenerated catalyst is fed to the riser reactor via regenerated catalyst delivery pipe2equipped with regenerated catalyst slide valve3for recycling use. The regenerated flue gas leaves the top of the regenerator after filtration.

3. Carrying out catalytic cracking reaction having instantaneous contact by closing valves B and C and opening valve A.

As shown inFIG. 1, an inert gas is introduced into riser5via nozzle4and used for elevating the regenerated catalyst from the regenerated catalyst delivery pipe to the top of the riser. The oil feedstock is fed to the joint of riser5and horizontal reaction pipe13via nozzle7, then contacts and reacts with the regenerated catalyst. The mixture of oil and catalyst enters horizontal reaction pipe13and reacts therein. The reaction oil-gas and catalyst enter the gas-solid separator14. Under the action of the gas-solid separator, oil-gas is rapidly separated from the catalyst to reduce the secondary cracking reaction of the products. The spent catalyst falls down to the stripping section at the lower part of settler15via the dipleg, and the reaction oil-gas enters the top of the settler via the uptake, then leaves the top after filtering off fine powders, and enters the subsequent separation system.

The spent catalyst in the stripping section of the settler is stripped. The stripped catalyst is fed to regenerator1via spent catalyst delivery pipe18equipped with spent catalyst slide valve17. The spent catalyst is regenerated by burning off coke in the regenerator and the regenerated catalyst is fed to the riser reactor via regenerated catalyst delivery pipe2equipped with regenerated catalyst slide valve3for recycling use. The regenerated flue gas leaves the top of the regenerator after filtration.

4. Carrying out down-flow catalytic cracking reaction by closing valve A and opening valves B and C.

As shown inFIG. 1, the regenerated catalyst from regenerated catalyst delivery pipe2is delivered into buffer tank9via riser5and delivery pipe8by elevation of an inert gas such as steam, nitrogen, etc. After stripping with steam, the catalyst enters the down-flow reaction tube via slide valve10, mixes with the oil feedstock fed from nozzle11, flows downwards, and reacts. The reaction oil-gas and catalyst enter gas-solid separator14. The gas at the top of buffer tank9is purged to vent via the controlling valve at the top. Under the action of the gas-solid separator, oil-gas is rapidly separated from the catalyst to reduce the secondary cracking reaction of the products. The spent catalyst falls down to the stripping section at the lower part of settler15via the dipleg, while the reaction oil-gas enters the top of the settler via the uptake, then leaves the top after filtering off fine powders, and enters the subsequent separation system.

The spent catalyst in the stripping section of the settler is stripped. The stripped catalyst is fed to regenerator1via spent catalyst delivery pipe18equipped with spent catalyst slide valve17. The spent catalyst is regenerated by burning off coke in the regenerator, and the regenerated catalyst is fed to the riser reactor via regenerated catalyst delivery pipe2equipped with regenerated catalyst slide valve3for recycling use. The regenerated flue gas leaves the top of the regenerator after filtration.

The above-mentioned four modes of operation are illustrative according to the present invention. Other ways of catalytic cracking reaction can also be performed by simply modifying the structure of the system of the present invention, for example, catalytic cracking reaction conducted in double risers can be carried out by incorporating an additional riser. Similar changes will be understood by persons skilled in the art, though such changes or modifications have not listed herein.

The following examples will further illustrate but is not intended to limit the catalytic cracking reaction-regeneration system of the present invention. The oil feedstock used in the experiments is an atmospheric residue from Daqing and the catalyst used is produced by the Catalyst Plant of Qilu Petrochemical Co. with a trademark of MLC-500. The properties of the oil feedstock and the catalyst can be referred to in Tables 1 and 2 respectively.

The present example shows the instance when the experimental unit of the present invention was used to conduct riser catalytic cracking.

The steps of the experiment as follows: valves B and C were closed but valve A was open. As shown inFIG. 1, the oil feedstock entered the riser reactor5via nozzle4, uniformly mixed at the inlet of the riser reactor with the regenerated catalyst from regenerated catalyst delivery pipe2, rapidly evaporated and reacted. The mixture of oil-gas and the catalyst ascended along the riser and entered cyclone separator14via horizontal reaction pipe13. Under the action of the cyclone separator, oil-gas was rapidly separated from the catalyst to reduce the secondary cracking reaction of the products. The spent catalyst fell down to the stripping section at the lower part of settler15via the dipleg, and the reaction oil-gas entered the top of the settler via the uptake, then left the top and entered the subsequent separation system after filtering off fine powders.

The spent catalyst in the stripping section of the settler was stripped. The stripped catalyst was fed to regenerator1via spent catalyst delivery pipe18equipped with spent catalyst slide valve17. The spent catalyst was regenerated by burning off coke in the regenerator, and the regenerated catalyst was fed to the riser reactor via regenerated catalyst delivery pipe2equipped with regenerated catalyst slide valve3for recycling use. The regenerated flue gas left the top of the regenerator after filtration.

The major operation conditions and product distribution are shown in Table 3.

This example shows the instance when the experimental unit of the present invention was used to conduct sectionally feeding experiment in the riser reactor.

The steps of the experiment were as follows: valves B and C were closed but valve A was open. As shown inFIG. 1, 50% by weight of the oil feedstock entered riser5via nozzle4, uniformly mixed at the inlet of the riser reactor with regenerated catalyst from regenerated catalyst delivery pipe2, rapidly evaporated and reacted, meanwhile, the remaining part of the oil feedstock entered the riser via nozzle6, contacted and reacted with the catalyst and the oil-gas flowing upwards from the bottom of the riser. The mixture of the reaction oil-gas and catalyst entered cyclone separator14via horizontal reaction pipe13. The spent catalyst fell down to the stripping section at the lower part of settler15via the dipleg, and the reaction oil-gas entered the top of the settler via the uptake, left the top and entered the subsequent separation system after filtering off fine powders.

The spent catalyst in the stripping section of the settler is stripped. The stripped catalyst was fed to regenerator1via spent catalyst delivery pipe18equipped with spent catalyst slide valve17. The spent catalyst was regenerated by burning off coke in the regenerator, and the regenerated catalyst was fed to the riser reactor via regenerated catalyst delivery pipe2equipped with regenerated catalyst slide valve3for recycling use. The regenerated flue gas left the top of the regenerator after filtration.

The major operation conditions and product distribution are shown in Table 4.

This example shows the instance when the experimental unit of the present invention was used to conduct down-flow catalytic cracking.

The steps of the experiment were as follows: valve A was closed but valves B and C were open. As shown inFIG. 1, by means of elevation of an inert gas such as steam, nitrogen, and so on, the regenerated catalyst from regenerated catalyst delivery pipe2was delivered into buffer tank9via riser5and delivery pipe8. After stripping with steam, the catalyst entered the down-flow reaction tube via slide valve10, mixed with the oil feedstock fed from nozzle1, flew downwards, and reacted. The reaction oil-gas and catalyst entered cyclone separator14. The gas at the top of buffer tank9was purged via the controlling valve at the top of the buffer tank. Under the action of the cyclone separator, oil-gas was rapidly separated from the catalyst to reduce the secondary cracking reaction of the products. The spent catalyst fell down to the stripping section at the lower part of settler15via the dipleg, while the reaction oil-gas entered the top of the settler via the uptake, then left the top and entered the subsequent separation system after filtering off fine powders.

The spent catalyst in the stripping section of the settler was stripped. The stripped catalyst was fed to regenerator1via spent catalyst delivery pipe18equipped with spent catalyst slide valve17. The spent catalyst was regenerated by burning off coke in the regenerator, and the regenerated catalyst was fed to the riser reactor via regenerated catalyst delivery pipe2equipped with regenerated catalyst slide valve3for recycling use. The regenerated flue gas left the top of the regenerator after filtration.

The major operation conditions and product distribution are shown in Table 5.