FI70528C - Apparatus for separating solids in circulating bed reactor. - Google Patents

Description

Apparatus for separating solids in a circulating bed reactor

Anordning avskiljning av fast material i Reaktor med circulerande bädd 1 70528

The present invention relates to an apparatus for use in connection with a circulating bed reactor for separating solids from reactor exhaust gases and returning solids to the reactor.

The object of the invention is to provide a device with which a solid can be efficiently separated from the exhaust gases of a circulating bed reactor and returned to the desired location in the reactor.

The rotary bed technology has been applied for a long time e.g. roasters and, increasingly, in various reactors such as combustors and carburettors. In known applications, the separation of solids from gases takes place in a conventional, constricted, bottom-shaped cycle separator, in which a cylindrical vortex chamber is fitted with a gas-carrying exhaust pipe and from which the solids are returned to the reactor via a gas trap. The purpose of the gas trap is to prevent the flow of reactor gases into the cyclone through the downcomer. The most common such gas lock is a mechanical shut-off device or, in more advanced devices, sand floating in a U-tube. Especially high temperature reactors become the solids I in the recovery system complex and expensive. Some of the air required to fluidize the gas trap flows upwards in the exhaust pipe and this has a detrimental effect, especially on the separation of light and fine material. In addition, the ascending gas flow reduces the conveying capacity of the downcomer.

In a conventional cyclone, a strong vacuum and a high axial flow rate are known to form in the middle. Because of this, a conventional cyclone tends to suck from the inlet tube. The resulting suction flow generally does not have a tangential velocity, so that almost all of the solids it carries pass through the cyclone center tube. Thus, a return system equipped with a conventional cyclone is very sensitive to the suction flows of the return pipe and requires a reliable gas trap.

In steam boiler applications, the use of a conventional cyclone results in an unfavorable structure because the conventional cyclone divides the boiler into a separate combustion chamber and a post-cyclone convection section, between which are located the material recovery devices.

Mechanical gas locks wear rapidly, especially in hot conditions, and often malfunction.

Solutions are also known in which a conventional cyclone is installed inside the reactor, in which case the entire solids recovery system is located inside the reactor. Cyclone corrosion and erosion problems are major drawbacks in this system because cooling of the support structure cannot be provided by simple means. In addition, the system suffers from the sensitivity of a conventional cyclone to the return suction of the return pipe.

The object of the invention is to provide a device with which the drawbacks present in the above-mentioned devices can be eliminated and with which a high degree of separation can be achieved. To achieve this goal, a 2-stage or multi-stage separation is used, in which the first step removes coarse abrasive particles at the lowest circumferential speeds Ia and in the subsequent steps smaller particles at high circumferential speeds Iaa.

The device according to the invention is characterized in that it comprises two differently sized, substantially horizontal, adjacent, concentric vortex chambers with concentric degassing openings with the vortex chambers, the smaller diameter of which is provided with a vortex chamber 370528 .

The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 shows an embodiment of the invention in vertical section, and Figure 2 shows a section of Figure 1 along the line B-B.

In the figures, reference numeral 1 denotes a vertical rotary bed reactor, the gases leaving the upper part of which are led to the first vortex chamber 2 of a separating device 4 provided with two horizontal vortex chambers Iaa through a gas trough tangentially connected thereto. The solid separated on the circumference of the vortex chamber exits the vortex chamber through the opening 5 therein and flows back to the reactor through the passage channel 6 tangentially connected to the vortex chamber. A second, smaller diameter vortex chamber 10 is connected to a degassing opening 8 at the second end 7 of the first vortex chamber. The solid separated on the circumference of the vortex chamber exits the vortex chamber through an opening therein and is returned to the reactor via a discharge duct 11 or discharged from the system.

The purified gases flow through the opening 14 in the end 13 of the vortex chamber 10 to the convection section 9.

In terms of flow technology, the system according to the invention differs from the conventional e.g. so that the solid returns to the reactor by a gas flow (1-10% of the gases).

Since the solids exit point is on the circumference of the vortex chamber, where the solids velocity is at its highest, good resolution is achieved.

11 70528

The system according to the invention provides obvious structural advantages, such as: - compact structure - expansion joints can be avoided - the circulating bed reactor can be pressurized without causing significant additional costs.

The solids can be removed from the vortex chamber through an opening extending over the entire width of the vortex chamber and the associated passage channel, or through a plurality of adjacent openings and passage channels.

Cooling ducts can be equipped with a cooling jacket I Ia if the solid to be returned to the reactor is to be cooled. Pa I aisles can be equipped with a valve so that some of the ducts can be closed. The connection points of the feed channels can be placed at different heights in the reactor so that the solid can be directed to the desired location.

The invention is not limited to the exemplary embodiment but can be modified and applied within the scope of the inventive idea defined by the claim.

Claims (1)

s 70528 Claims A device used in connection with a circulating bed reactor for separating solids from reactor exhaust gases and returning solids to the reactor, characterized in that it comprises two substantially sized, substantially horizontal, adjacent, concentric vortex chambers (2, 10) with convex chambers with vortex chambers (8, 14) and of which the smaller diameter (10) is provided with a gas inlet (8) connected to the gas outlet (8) of the larger diameter vortex chamber (2), a gas connected to the reactor (1) tangentially to the larger vortex chamber. (3), as well as outlets (5, 15) on the circumference of the vortex chambers, to which the separated solids return channels (6, 11) connected to the reactor are connected.