JPS6254536B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention The device for feeding solid particles into a container consists of a loading tube 2, which has a Coanda surface 9.
The lower end or the vicinity of the lower end is surrounded by a gas supply chamber 7 terminating in the gas supply chamber 7 . The slot 10 between the outlet from the loading tube 2 and the beginning of the Coanda surface 9 forms a Coanda nozzle. Preferably, the throttle 3 is fixed within the loading tube 2 to form an annulus 4 down which the particles flow into the slot 10. The gas supply line 8 preferably enters tangentially into the gas supply 7 and supplies gas to the Coanda nozzle. This device is particularly suitable for loading catalyst into reactors. The present invention relates to a device for feeding solids, in particular a device for loading a reactor with a catalyst. Catalytic methods are used in the petroleum refining industry and the chemical industry, which require loading a reactor with a catalyst. The catalyst must be removed and replaced periodically. In a typical loading method, the catalyst is first placed in a drum or larger container and lifted to the top of the reactor, then placed into a hopper and dropped into the reactor via a "sock". This "sock" is a long flexible tube that is held at one end just above the catalyst bed level and raised as the catalyst level in the reactor rises during the loading operation. The catalyst bed must often be scraped on top to ensure even packing. Performing this task requires human access to the reactor, which creates problems in designing reactors that allow access. Furthermore, this work is unpleasant and tends to damage the catalyst.
It has been found that it is difficult to ensure uniform packing and prevent voids and therefore this loading method results in low values of catalyst packing density. This can result in poor system performance due to less catalyst weight being present in the reactor or due to catalyst bed slump leaving voids at the top during use. When one lip of the slot opening through which fluid flows out under pressure is gradually expanded and extended from the axis of the slot exit, the flow of fluid exiting the slot tends to stay at this extended lip. It has been known. This action causes a pressure drop in the surrounding fluid, causing a flow of fluid in the direction of the area of low pressure. This physical phenomenon is known as the Coanda effect, and objects exhibiting this effect are known as Coanda bodies. A Coanda nozzle may be defined as a nozzle capable of discharging high pressure fluid into another low pressure fluid through a narrow slot of selected dimensions having a surface of the Coanda body substantially adjacent one wall of the slot. can. Now, researchers have discovered a method for feeding solid particles into a container that uses the Coanda effect to disperse falling solid particles so that they traverse the container and are evenly distributed. According to the invention, therefore, there is provided a device for supplying solid particles to a container, which device comprises a loading tube, surrounded at or near its base by a gas supply chamber terminating in the Coanda surface, and comprising The slot between the outlet and the beginning of the Coanda surface forms a Coanda nozzle. Preferably, the loading tube has a coaxially aligned cylinder therein at its lower end to provide an annulus for the passage of solid particles. This cylinder is hereinafter referred to as a throttle. The throttle functions to direct the particle stream near the Coanda nozzle and to adjust the particle feed rate. In use, the annulus is filled with particles to prevent the tendency of atmospheric air to descend down the loading tube and into the area of the Coanda nozzle. Alternatively, this effect can be achieved using a smaller diameter loading tube without the use of a throttle. The gas supply channel preferably enters the gas supply chamber in a tangential direction. The apparatus is particularly useful for loading catalyst into reactors and obtaining high packing densities. The catalyst can be granular, cylindrical or spherical up to 1/8 inch in diameter. According to another aspect of the invention, a method is provided for supplying solid particles to a container, the method comprising flowing the particles down a loading tube and introducing gas into a chamber terminating in a Coanda nozzle surrounding the outlet of the loading tube. and entraining the particles in the gas stream exiting the Coanda nozzle at or near the base of the loading tube so as to distribute the particles substantially uniformly over the cross-sectional area of the vessel. Preferably, the particles are allowed to fall into an annulus within the loading tube prior to entrainment. In most cases air will be a suitable working fluid, but under hazardous conditions an inert gas such as nitrogen may also be used. The dispersion of particles achieved by entrainment depends on many variables including the geometry of the equipment, e.g. the diameter of the loading tube, the width of the Coanda slot, the shape (e.g. radius) of the Coanda surface, the rate of particle feed and the pressure of the gas feed. Depends on it. These variables can be easily adjusted to provide the desired uniform distribution. The width of the slot is suitably in the range of 0.1 to 3.0 mm, preferably in the range of 0.2 to 2.0 mm. The width of the annular portion is suitably in the range of 3 to 25 mm, preferably in the range of 5 to 20 mm. In particular, it is preferred that the gas is introduced tangentially into the gas chamber surrounding the loading tube. Gas pressure is an easily adjustable variable that can be adjusted to change the distribution of particles below the discharge end of the loading device. However, the gas pressure can be kept constant if desired, and in many cases this will be the simplest method of operation. Suitable gas pressures range from 0.35 to 7 barg, preferably from 0.7 to 3.5 barg. A particular advantage of operating the loading device according to the invention is that it provides a way to uniformly fill the reactor without having to raise and lower the loading tube during filling. Therefore, the gas flow can be adjusted early in the loading process to improve particle distribution until the particles reach the bottom end of the reactor to be filled. As the level of packed particles increases in the reactor, the gas flow can be readjusted to maintain good distribution. The rate of particle feeding can be adjusted by varying the diameter of the throttle or by adjusting the position of the cone that partially blocks the exit from the loading tube. The present invention will now be described with reference to FIGS. 1 and 2 of the accompanying drawings. The catalyst is placed in a storage hopper 1, at the outlet of which a loading tube 2 with a throttle 3 is inserted, which together with the tube 2 forms an annular portion 4. The throttle 3 has a conical cover 5 on top and is positioned by a support 6. The tube 2 is surrounded at its lower end by a supply chamber 7 for air supplied by a supply conduit 8 . The outlet from chamber 7 develops into a Coanda surface 9. A slot 10 is formed between the tube 2 and the outlet of the chamber 7, and in conjunction with the Coanda surface 9 forms a Coanda nozzle. The throttle 3 terminates at its lower end in a conical cover 11. In use, a supply line 8 is used to direct the flow of air into the chamber 7.
Enter tangentially through . Air is then forced out of the coanda slot 10 and follows the coanda surface 9 adjacent the slot 10 creating a swirl cone of air. The catalyst particles contained in the hopper 1 fall into the annulus 4 and are entrained by the airflow around the slot 10 and distributed evenly over the bottom of the reactor (not shown). In a prototype device made of heat-resistant glass, good particle dispersion was obtained with the following dimensions. Diameter of loading tube 2: 33 mm Width of slot 10: 1 mm Radius of Coanda surface 9: 5 mm Diameter of loaded container: 600 mm The prototype was not equipped with a throttle cylinder 3. The catalyst loader was constructed from mild steel and had the following dimensions: Inner diameter of loading tube 2: 95mm Height of loading tube 2: 915mm Outer diameter of throttle 3, Example 1: 76mm Outer diameter of throttle 3, Examples 2 to 5: 70mm Total height of throttle 3, from tip to tip :200
mm Height of straight side of throttle 3: 160 mm Width of throttle 10: 0.25 mm Radius of Coanda surface 9: 15 mm Examples 1 to 5 Using the catalyst loading apparatus illustrated in FIGS. A commercially available 1.5 mm extruded cobalt molybdate/alumina catalyst was loaded. A 100 kg batch of catalyst was loaded into a cylindrical vessel, which was a 1.2 m diameter vessel with a dispensing nozzle located 700 mm above the center of its bottom. Five batches of catalyst were loaded and the catalyst packing density and loading rate were determined in each case. Catalyst packing density was taken as the average value of five bulk densities measured on samples taken throughout the catalyst bed. These samples were collected in a graduated container, with one sample being at the center bottom of the loading container and the other samples being located at cardinal directions on the circumference with a radius of 380 mm from the center bottom. Apart from the beginning and end of loading, the level of catalyst in the feed hopper was kept constant.
The results are shown in Table 1. The catalyst packing density is 0.63 g/ml, which is 12.5% lower than the comparative value of 0.56 g/ml obtained by conventional loading technology.
There was an increase in The loading rate of 0.5 to 1 ton/hour depends on the annular gap between the throttle and the loading tube and can be increased or decreased if desired. 【table】

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the catalyst loading device, Figure 2 is the
It is a sectional view taken along the line A-A' in the figure. 1... Hopper, 2... Loading tube, 3... Throttle, 4... Annular part, 5... Conical cover, 6
... Support body, 7 ... Air supply chamber, 8 ... Supply pipe line, 9 ... Coanda surface, 10 ... Slot, 1
1...Conical cover.

Claims (1)

Claims: 1. The loading tube 2 is surrounded at or near its lower end by a gas supply chamber 7 terminating in the Coanda surface 9;
is equipped at its lower end with a cylindrical throttle 3 coaxially aligned in its interior, providing an annular portion 4 for the passage of the solid particles and further connecting the outlet from the charging tube 2 with the beginning of the Coanda surface 9. A device for feeding solid particles into a container with a loading tube 2, characterized in that the slot 10 between them forms a Coanda nozzle. 2. Device for supplying solid particles to a container according to claim 1, characterized in that the gas supply line 8 enters the gas supply chamber 7 tangentially. 3. The device for supplying solid particles into a container according to claim 1 or 2, wherein the width of the slot 10 is in the range of 0.1 to 3.0 mm. 4. The device for supplying solid particles to a container according to any one of claims 1 to 3, wherein the width of the annular portion 4 is in the range of 3 to 25 mm. 5. A method for supplying solid particles to a container, which comprises causing the solid particles to flow down into the loading tube 2 and entraining the solid particles at or near the lower end of the loading tube 2 by supplying a gas. Loading tube 2 prior to entrainment with gas
feeding the gas into the supply chamber 7 which drops into the annular part 4 formed by the throttle 3 therein and then terminates in the Coanda surrounding the outlet of the loading tube 2;
The solid particles are entrained in the gas flow exiting the Coanda slot 10 at or near the lower end of the loading tube 2 so that the solid particles are distributed substantially uniformly over the entire cross-section of the vessel. How to feed the container. 6. A method according to claim 5, characterized in that the gas is introduced tangentially into the gas supply chamber 7. 7. A method for feeding solid particles into a container according to claim 5 or 6, characterized in that the gas is introduced under a pressure in the range 0.35 to 7 bar (gauge pressure).