PROCESS FOR CARRYING OUT REACTIONS ON PREHEATED PARTICLES

Abstract

The invention relates to a process for carrying out reactions on preheated particles, comprising: (a) providing particles in a buffer container; (b) feeding the particles from the buffer container into a reactor via a feed line; (c) withdrawing the particles from the reactor, wherein the particles are heated in the feed line.

Claims

1. A process for carrying out reactions on preheated particles, comprising: (a) providing particles in a buffer container; (b) feeding the particles from the buffer container into a reactor via a feed line, which is not directly connected to the entrance of the reactor, and feeding reactants via a reactant feed, which is connected to the entrance of the reactor; (c) withdrawing the particles from the reactor, wherein the particles are heated in the feed line.

2. The process according to claim 1, wherein for heating the particles a combustible and an oxidant are added and the particles are heated by combustion of the combustible and the oxidant.

3. The process according to claim 2, wherein the combustible is selected from the group consisting of hydrogen, methane, ethane, propane and butane.

4. The process according to claim 2, wherein the oxidant is an oxygen comprising gas.

5. The process according to claim 4, wherein the oxygen comprising gas is air, diluted air, oxygen enriched air, oxygen or a mixture of oxygen and an inert gas.

6. The process according to claim 2, wherein the oxidant is added sub stoichiometrically.

7. The process according to claim 2, wherein the combustible and the oxidant are fed into the feed line in counter current to the flow direction of the particles.

8. The process according to claim 1, wherein the particles are heated in the feed line to a temperature in the range from 400 to 1200? C.

9. The process according to claim 1, wherein after being withdrawn from the reactor, the particles are recycled into the buffer container.

10. The process according to claim 1, wherein the particles are regenerated in the buffer container.

11. The process according to claim 1, wherein the temperature of the particles in the buffer container is in the range from 400 to 850? C.

12. The process according to claim 1, wherein the reaction on preheated particles is a catalytic cracking reaction.

13. The process according to claim 1, wherein the reaction on preheated particles is a pyrolysis reaction.

Description

[0052] In the drawing:

[0053] FIG. 1 shows a laboratory test unit for operating the process for carrying out reactions on preheated particles;

[0054] FIG. 2 shows an apparatus for operating the process for carrying out reactions on preheated particles in a second embodiment.

[0055] FIG. 1 shows a test unit for operating the process for carrying out reactions on preheated particles.

[0056] A test unit 1 for operating the process for carrying out reactions on preheated particles in the gas phase comprises a buffer container 3 for the particles a reactor 5 and a separator 7 in which the reaction mixture is separated from the solid particles.

[0057] For carrying out the reaction in the reactor 5, liquid or gaseous reactants are fed into the reactor via reactant feed 9. Further, the buffer container 3 is connected to the reactor by a feed line 11. When the test unit is operated, at least one reactant is fed into the reactor 5 via the reactant feed 9.

[0058] To support feeding the at least one reactant into the reactor 5 a suitable gas or liquid conveying device, for example a pump 13 or a compressor may be used. The gas or liquid conveying device may be any pump or compressor which allows transport of the at least one reactant into the reactor. If the at least one reactant is preheated, usually a gas or liquid conveying device is used which is resistant towards the temperature of the at least one reactant flowing through the gas or liquid conveying device.

[0059] To feed the particles into the reactor, additionally valve 15 is opened. By opening valve 15 particles 17 flows from the buffer container 3, through the feed line 11 into the reactor 5.

[0060] The reactor 5 in the embodiment shown in FIG. 1 is a tubular reactor through which at least one reactant and the particles flow in co-current from top to bottom. Thus the flow of the particles and the at least one reactant in the reactor 5 is supported by gravity.

[0061] According to the invention, the particles are preheated in the feed line 11 to a temperature which is above the temperature of the reaction to be carried out in the reactor before entering the reactor 5. By preheating the particles before entering the reactor 5 it is for example possible to provide necessary energy which is used as starting energy for an exothermic reaction or energy which is used to operate an endothermic reaction in the reactor 5. For heating the particles 17, any suitable heating means 19 can be used. A suitable heating means 19 for example is an internal heater like a heating conductor. A suitable external heater for example is realized by heating the walls of the feed line 11, for example by electrical heating elements which enclose the feed line 11. Further, the heating means 19 also may comprise an inductive heating of the particles in the feed line 11 which affords that the particles or the feed line is susceptible to induction. To obtain particles susceptible to induction, it is for example possible to provide particles having a magnetizable support. Besides heating the particles by a heating means 19 it is also possible and particularly preferred to heat the particles by feeding a combustible and an oxidant into the feed line 11. In the feed line 11 the combustible reacts with the oxidant and thereby heat is generated.

[0062] The temperature to which the particles are heated depends on the reaction which shall be carried out in the reactor 5. Preferably, the particles are heated to a temperature which is 0 to 500? C. above the temperature in the reactor, preferably 100 to 400? C. above the temperature in the reactor and particularly 100 to 300? C. above the temperature in the reactor. If the reaction is a fluid catalytic crack reaction, the temperature to which the particles are heated preferably is in the range from 150 to 200? C. above the reactor temperature.

[0063] After flowing through the reactor 5, the gaseous reaction mixture and the particles flow into the separator 7. In the separator 7 the gaseous reaction mixture is separated from the solid particles. In the embodiment shown in FIG. 1, the solid particles are collected in the separator 7 and the gaseous reaction product is withdrawn via exit line 21. The gaseous reaction product then can be transported to a unit for further processing, for example to remove impurities from the reaction product and if only a part of the at least one reactant is transformed, separating the product from the non-reacted reactant. Further, also an analysis can take place for analyzing the reaction product.

[0064] The particles collected in the separator also can be removed. To remove the particles, a valve 23 is provided which is opened to remove the particles from the separator 7. Preferably, to remove the particles, an inert gas flows through the particles forming a fluidized bed and the particles are removed from the top of the fluidized bed. A suitable inert gas for example is nitrogen.

[0065] After being removed from the separator, the particles can be collected in a device for particle recovery and optionally regenerated externally. After being worked-up in the particle recovery, the particles can be recycled into the buffer container 3 and be reused.

[0066] As clearly can be seen in FIG. 1, the individual parts of the test unit 1 are separated from each other and the buffer container 3 and the feed line 11 do not form an integral part of the reactor 5. The separated components may be connected by means which are known to the person skilled in the art. The components may by connected by screw connections or welding. The term feed line 11 refers to the feed line 11 for preheated particles which are preheated in the particles feed line. The entrance of the reactor 5 is connected to the reactant feed 9 which supplies the reactant.

[0067] Preferably, the test unit 1 is used in the laboratory scale or scale of a small pilot plant. Thereby, the buffer container 3 preferably has a capacity for the uptake of particles which is in the range from 0.15 to 15 Liters, more preferred in a range from 0.2 to 10 Liters.

[0068] The feed line 11 for the transfer of particles from the buffer container 3 to the reactor 5 preferably has a length in a range from 0.3 to 5 m, whereby a length from 0.5 to 2 m is further preferred. Preferably the inner diameter of the feed line 11 is in a range from 0.2 to 2 cm, more preferred in a range from 0.3 to 1.5 cm. Heating of the particles in the feed line 11 particularly preferably is based on the use of a heating device which is arranged in direct proximity to the outer part of the feed line 11.

[0069] It is preferred that the reactor 5 has a length in a range from 0.3 to 3 m, more preferred the reactor 5 has a length in a range from 0.5 to 2 m. The inner diameter of the reactor preferably is in a range from 0.3 to 2 cm, more preferred in a range from 0.5 to 1.8 cm, and particularly in a range from 0.7 to 1.5 cm.

[0070] In order to carry out the process according to the invention it is preferred that the particles which are employed within the process have a mean particle diameter which is in a range from 20 to 300 ?m.

[0071] FIG. 2 shows an apparatus for operating the process for carrying out reactions on preheated particles in a second embodiment.

[0072] The embodiment shown in FIG. 2 particularly differs from the embodiment of FIG. 1 in that according to FIG. 2 the particles circulate. Further, the reactor 5 in the embodiment shown in FIG. 2 is a riser reactor in which the gas and the particles flow from the bottom to the top contrary to the direction of gravity. To operate the reactor of the embodiment in FIG. 2, the velocity of the reactants and the resulting reaction mixture obtained by the reaction in the reactor 5 must be sufficiently high to transport the particles through the reactor 5.

[0073] The particles are provided in the buffer container 3 and flows from the buffer container 3 through the feed line 11 into the reactor 5. The buffer container 3 preferably also acts as regenerator for the particles. In the feed line 3 the particles are heated by a suitable heating means which may correspond to the heating means 19 described above for the embodiment shown in FIG. 1. However, particularly preferably the particles are heated by feeding a combustible, for example methane, ethane, propane, butane or hydrogen, and an oxidant, for example oxygen, into the feed line 11 via a feed line 27 for the combustible. By oxidation of the combustible the particles are heated in the feed line. The amount of combustible and oxidant is selected such that the total amount of oxidant reacts with the combustible in the feed line 11 to avoid oxidant being fed into the reactor 5, as particularly in a catalytic cracking reaction the oxidant has a negative impact on the cracking reaction forming undesired by-products, particularly carbon monoxide.

[0074] From the reactor 5, the reaction mixture and the particles flow into the separator 7 which also may be called stripper. In the separator 7 the reaction product is separated from the solid particles. To separate the particles from the reaction product, the separator 7 for example can be a cyclone.

[0075] In the embodiment shown in FIG. 2, the solid particles collects at the bottom of the separator 7 and is transported from the separator 7 via a connecting line 25 into the buffer container 3. The temperature in the buffer container 3 is below the reaction temperature to allow the catalyst to regenerate in the buffer container 3. To support regeneration of the catalyst in the buffer container 3, a gas, for example air, can be added to the buffer container 3 via a gas feed line 29. The gas preferably is added via a suitable gas distributor 31 to generate a fluidized bed in the buffer container 3. By this fluidized bed it can be ensured that all catalyst particles can come into contact with the gas. Further, by generating a fluidized bed it can be avoided that particles agglomerate.

[0076] To keep the pressure in the buffer container 3 constant, an exhaust line 33 is connected to the buffer container 3 through which flue gas can be withdrawn. If necessary, the flue gas can be subjected to a waste gas treatment and then either collected or emitted to the environment.

[0077] For the circulation of the particles, the apparatus shown in FIG. 2 particularly is suitable for being used in industrial scale processes whereas the apparatus shown in FIG. 1 particularly is used as a test unit for experimentation.

LIST OF REFERENCE NUMERALS

[0078] 1 test unit [0079] 3 buffer container [0080] 5 reactor [0081] 7 separator [0082] 9 reactant feed [0083] 11 feed line [0084] 13 pump [0085] 15 valve [0086] 17 particles [0087] 19 heating means [0088] 21 exit line [0089] 23 valve [0090] 25 connecting line [0091] 27 feed line for the combustible [0092] 29 gas feed line [0093] 31 gas distributor [0094] 33 exhaust line