Abstract
The present invention addresses to a third stage system with self-bleeding by means of the use of an internally or externally installed ejector with application in all multicyclone systems operating at positive pressure, whether for application in particulate abatement or protection systems of turbo-expanders or in industrial units that involve the need of recovering solid products carried by the process gas, aiming at eliminating the need for any additional separation systems using cyclones or filters to carry out the bleeding of the cyclone legs.
Claims
1. A third stage system with self-bleeding, characterized in that it comprises a recycle ejector (13) where the suction side is directly connected to the central region or the top of the third stage cyclone vessel (6) via an auxiliary piping (16) and its discharge connected to the central feed of the third stage cyclone vessel (6).
2. The third stage system with self-bleeding according to claim 1, characterized in that it optionally comprises a flow meter (12), which is coupled to the ejector output (13), in which said ejector uses a motive fluid stream (14) variable accordingly.
3. The third stage system with self-bleeding according to claim 1, characterized in that a vortex limiter (15) can be installed in the top region of the cyclone leg.
4. The third stage system with self-bleeding according to claim 2, characterized in that the recycle ejector (13) is internally or externally installed in the third stage cyclone vessel (6).
5. The third stage system with self-bleeding according to claim 2, characterized in that the flow rate of motive fluid of the ejector (14) promotes the aspiration of a stream flow rate in the range of 2 to 5%, preferably, in relation to the flow rate of the gases that enter the third stage vessel (6), wherein the restriction for the maximum value of flow rate of the stream to be aspirated will be due to the excessive consumption of motive fluid or erosive aspects.
6. The third stage system with self-bleeding according to claim 2, characterized in that the motive fluid of the ejector (14) is air, fuel gas, natural gas or steam.
7. The third stage system with self-bleeding according to claim 2, characterized in that the flow meter (12) is of the Venturi type.
8. The third stage system with self-bleeding according to claim 2, characterized in that the flow meter (12) and the recycle ejector (13) are built with ceramic internal parts.
9. A use of the third stage system as defined in claim 1, characterized in that said system is applied in multicyclone systems operating at positive pressure, particulate abatement systems, turbo-expander protection systems and in industrial units involving the need of recovering solid products carried by the process gas.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic way and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:
[0027] FIG. 1 illustrating a third stage system vessel with multiple cyclones in parallel, represented by: catalyst gas feed (1), purified gas or little catalyst output (2), catalyst and bleed gas (3), catalyst and bleed gas (4), separate catalyst+carrier or bleed gas output (5) and, dp1 and dp2 are the pressure differentials, dp1 being different from dp2;
[0028] FIG. 2 is illustrating a complete third and fourth stage cyclone system, typical of the state of the art, with perfect alignment to bleed the cyclones, represented by: catalyst gas feed (1), purified gas or little catalyst output (2), which is sent to the turbo-expanders for electric energy generation or for the recovery of thermal energy and or carbon monoxide burning, separate catalyst+carrier or bleed gas output (5), third stage cyclone vessel (6), pneumatic carrying auxiliary air of the catalyst (7), restriction orifice (8), fourth stage cyclone (9), collected catalyst outlet (10), catalyst accumulation silo (11);
[0029] FIG. 3 is illustrating a typical state-of-the-art system, where it shows a mass balance of the main systems, considering the performance of a Third and Fourth Stage Cyclone System working with 84% global collection efficiency, consisting of a third stage cyclone running at 88% collection efficiency and a fourth stage cyclone running at 95% collection efficiency. Thus, the inlet flow rate of the catalyst gas (1), coming from the regenerator output, and the other streams represented by 2, 3, 4, 5 and 6, are 25 kg/h, 3 kg/h, 22 kg/h, 21 kg/h, 1 kg/h and 4 kg/h, respectively. There can be seen a 25% increase in atmospheric emission due to the presence of the fourth stage cyclones, since the emission into the atmosphere of the third stage alone is 3 kg/h, while with the presence of the fourth stage it becomes 4 kg/h, due to the addition of 1 kg/h;
[0030] FIG. 4 is illustrating a third stage cyclone system with the ejector (13) internal to the vessel (6), whose purpose is to bleed the multiple third stage cyclones via recycle of the gas and catalyst present in the upper region of the third stage cyclone vessel (6). In this configuration, the ejector is positioned parallel to the cyclones and its output is feeding the bleed gas at the lower part or base of the distribution duct for the feeds of the gas-catalyst stream to the multiple cyclones in parallel, in a region after the inlets of the multiple cyclones operating in parallel. The set configuration is given by: catalyst gas feed (1), purified gas or little catalyst output (2) which is sent to the turbo-expanders for electrical energy generation, separate catalyst+carrier or bleed gas output (5), third stage cyclone vessel (6), pneumatic carrying auxiliary air of the catalyst (7), catalyst accumulation silo (11), Venturi type flow meter (12), optional, ejector (13), motive fluid of the ejector (14), vortex limiter (15), optional;
[0031] FIG. 5 is illustrating a third stage cyclone system with the ejector internal to the vessel (6) with the same objective of bleeding the multiple third stage cyclones via recycle of the gas and catalyst present in the upper region of the third stage cyclone vessel (6). In this position, the ejector (6) is inserted internally to the vessel (6) and external to the cyclones and its output is feeding the bleed gas at the upper part in the distribution duct, inlet of the catalyst gas stream to the multiple cyclones connected in parallel, in a region before the inlets of multiple cyclones. The set configuration is given by: catalyst gas feed (1), purified gas or little catalyst output (2) that is sent to the turbo-expanders for electrical energy generation, separate catalyst+carrier or bleed gas output (5), pneumatic carrying auxiliary air of the catalyst (7), catalyst accumulation silo (11), Venturi type flow meter (12), optional, ejector (13), motive fluid of the ejector (14), vortex limiter (15), optional, auxiliary piping (16);
[0032] FIG. 6 is illustrating a third stage cyclone system with the ejector external to the vessel (6), with the same objective of bleeding the multiple third stage cyclones via recycle of the gas and catalyst present in the upper region of the third stage cyclone vessel (6). In this configuration, the ejector is positioned externally to the vessel (6) and its outlet is feeding the bleed gas into the distribution duct for the feeds of the catalyst gas stream (1) to the multiple cyclones that operate in parallel. The configuration of the set is given by: catalyst gas feed (1), purified gas or little catalyst output (2), which is sent to the turbo-expanders for electrical energy generation, separate catalyst+carrier or bleed gas output (5), third stage cyclone vessel (6), pneumatic carrying auxiliary air of the catalyst (7), catalyst accumulation silo (11), Venturi type flow meter (12), optional, ejector (13), motive fluid of the ejector (14), vortex limiter (15), optional, auxiliary piping (16). There is no connection to the fourth stage cyclone.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The present invention through the use of ejector (13) preferably installed internally or externally to the vessel (6) has a simplicity of installation, in which it will recirculate or recycle a flow rate of the order of 3% of the region of the top of the vessel, a region of low or diluted catalyst concentration, where the third stage cyclones are installed for the gas feed duct, carrying catalyst from the diluted catalyst region of the third stage system.
[0034] The invention also makes use of vortex limiters, to contain the internal vortex inside the cyclone, reducing catalyst carrying and pressure differential between the inlet and the top of the cyclone leg.
[0035] The internal or external ejector (13), as shown in FIGS. 4, 5, and 6, respectively, through the action of the motive fluid (14), manages to displace the bleeding stream from a point of lower pressure (inside the vessel (6), region where the multiple cyclones discharge the stream concentrated in particulate matter and bleed gas) to a higher pressure point (inlet of the feed of the multiple third stage cyclones of the vessel (6)). This stream mixes with the main flow of gases coming from the regenerator and re-enters the third stage cyclones, which become responsible for removing the particles present in the same, completely eliminating the need for a fourth stage cyclone. And due to the effect of carrying/capturing the small particles in the form of clusters (agglomerates of fine and coarse particles) within the multiple cyclones due to mixing with the stream from the regenerator, which has a coarser granulometric profile, of the order of 4 times, a phenomenon recognized in the state of the art as capture of fine particles by coarse particles; therefore, the impact on the emission of particulate matter due to the recycle of the bleed stream of the cyclones at the vessel outlet with the third stage cyclones is extremely low, compared to the impact of the presence of the fourth stage cyclone; in addition, the bleeding stream from the upper region of the vessel (6) with fine catalyst is difficult to separate, when treated alone.
[0036] The flow rate of the bleed stream at the outlet of the ejector (13) depends on the flow rate of the motive fluid in the ejector (14), which is adjusted from the measurement of the aspirated flow rate, which can be known through the installation of an instrument for measuring flow rate of the Venturi type (12), optional, between the third stage vessel (6) and the ejector (13) or even at the ejector outlet in the case of internal installation. It is recommended that both the Venturi (12) and the recycle ejector (13) be built with ceramic internal parts, resistant to the abrasion of the catalyst particles. The motive fluid flow rate (14) to the recycle ejector must be increased until the flow rate measurement of the aspirated stream is at the desired value, usually from 2 to 5% of the gas flow rate that enters the third stage vessel (6). The presence of the vortex limiter (15) also allows the operation of excessive bleeding, as it limits the penetration of the internal vortex at the top of the leg of the multicyclones. It is important to point out that, in this configuration, both the energy present in the bleed stream and in the motive fluid of the ejector will be available for the generation of electrical energy in the turbo-expander.
[0037] Therefore, there is no longer a restriction on the bleed flow rate of the legs of the second stage cyclones regarding the loss of electrical energy generation capacity.
[0038] The self-bleeding third stage system according to the present invention and illustrated in FIG. 4 comprises an internal ejector (13) in which the suction side is connected to the diluted phase in the central region of the third stage cyclone vessel (6) and its discharge connected to the central inlet/feed of the third stage cyclone, where it mixes with the main flow of gases from the regenerator and re-enters the third stage cyclone and an instrument for measuring flow rate of the Venturi type (12), optional, installed on the ejector outlet (13).
[0039] As can be seen in FIG. 5, a second embodiment of the present invention, in which the third stage system comprises an internal ejector (13) located on the side of the top of the third stage cyclone vessel (6), in which it has the suction side connected to the diluted phase in the central region of the third stage cyclone vessel (6), via an auxiliary piping (16) and its discharge connected to an interconnection piping to the third stage cyclone, where it mixes with the main flow of gases from the regenerator and re-enters the third stage cyclone. There is also an instrument for measuring flow rate of the Venturi type (12), optional, installed at the ejector outlet (13).
[0040] As can be seen in FIG. 6, a third embodiment of the present invention, in which the third stage system comprises an external ejector (13) located on the side of the top of the third stage cyclone vessel (6), in which it has the suction side connected with the diluted phase in the central region of the third stage cyclone vessel (6), via an auxiliary piping (16) and its discharge interconnected with the catalyst gas feed piping (1) and an optional Venturi type flow meter (12) coupled to the ejector outlet (13).
[0041] The motive fluid of the ejector (14) depending on whether the combustion gas is flammable or not, may be: air, fuel gas, natural gas or steam.
[0042] Optionally, the vortex limiter (15) can be installed in the top region of the cyclone leg in all embodiments of the present invention, to increase collection efficiency, reduce erosion at the top of the leg of the multicyclones of the Third Stage Cyclone System and reduce motive fluid consumption (14).
[0043] It should be noted that, although the present invention has been described in relation to the attached drawings, it may undergo modifications and adaptations by technicians skilled on the subject, depending on the specific situation, but provided that within the inventive scope defined herein.
