RU2320922C1 - Cap-type gas distributing grate - Google Patents

Abstract

FIELD: power engineering, chemical and metallurgical industries.

SUBSTANCE: invention relates to design of gas distributing grates for fluidized bed devices. Proposed cap-type gas distributing grate has fixed caps installed in plate with inlet ports provided with holes arranged in side walls of caps at different levels from plate is furnished additionally with movable cores, each being placed in space of each cap from side of inlet port of cap.

EFFECT: provision of uniform fluidizing of bed within wide range of control of capacity of fluidized bed devices.

4 cl, 4 dwg

Description

The invention relates to the design of gas distribution grids and can be used in the energy sector, in the chemical and metallurgical industries, where fluidized bed devices are used.

The main structural element of fluidized bed devices is a gas distribution grill designed for gas supply and uniform liquefaction of the layer material over its surface. The uniformity of gas distribution and fluidization of the layer affects the quality of technological processes carried out on the grate, and therefore is its important characteristic. The uniformity of the liquefaction directly depends on the aerodynamic resistance of the lattice - the higher the resistance, the more uniform the liquefaction of the layer.

Known gas distribution grilles containing movable or fixed caps installed in plates with inlet windows (Buevich Yu.A. Inkjet fluidization / Yu.A. Buevich, G.A. Minaev. - M.: Chemistry, 1984. - P.126- 128, Fig. 4.10). Movable caps made in the form of valves are designed to prevent the failure of the layer material into the space under the grid when the fluidized bed device is stopped (Buevich Yu.A. Inkjet fluidization / Yu.A. Buevich, G.A. Minaev. - M.: Chemistry, 1984. - S.126-128, Fig. 4.10, positions. 26, 46, 49, 51, 54). The fixed caps are provided with holes of different shapes and sizes located in the side walls of the caps horizontally or inclined to the surface of the plate. The holes can be placed along the height of the cap in one or more tiers, or the cap can be made with perforation in height. The fixed caps, as well as the movable ones, are also designed to prevent the failure of the layer material into the space under the grill when the fluidized bed devices are stopped by selecting the hole sizes so that the layer material that has fallen into them and is at an angle of repose does not wake up in the space under the grill (Buevich Yu.A. Inkjet fluidization / Yu.A. Buevich, G.A. Minaev. - M.: Chemistry, 1984. - S.126-128, Fig. 4.10, positions. 1, 2, 5, 6, 15, 32, 34, 36, 39).

Among the known technical solutions, the closest to the present invention, selected as a prototype, is a gas distribution cap containing fixed caps in the plate with inlet windows, provided with openings located in the side walls of the caps at different levels from the plate, to create a stable fluidized bed. The holes can be made with different diameters, and the holes of small diameter are placed in the spaces between the holes of larger diameter (USSR author's certificate No. 77693, Cl. 24f, 1).

A common significant drawback of the above-described cap gas distribution grids is the unevenness of the liquefaction of the bed with corresponding violations of the parameters of the processes occurring in it, leading to emergency shutdowns, which is the reason for the significant limitation of the range of regulation of the performance of fluidized bed devices. This is explained by the dependence of the aerodynamic drag of these cap gas distribution grids on the flow rate of the fluidizing agent, i.e. gas, which is why the operation of fluidized bed devices while reducing productivity by reducing the flow rate of the fluidizing agent is accompanied by a sharp drop in the aerodynamic drag of the grill.

The present invention solves the problem of ensuring uniformity of the fluidization of the layer in a wide range of performance control devices fluidized bed.

To achieve this technical result, a cap gas distribution grill containing fixed caps in the plate with inlet windows, provided with holes located in the side walls of the caps at different levels from the plate, according to the invention is equipped with movable cores, each of which is placed in the cavity of each cap from the input side cap windows.

The core can be made in the form of a mating piston element in the upper part and a shank tapering downward in the lower part, installed inside the cavity of the cap with the possibility of reciprocating movement of the piston element in the area of the holes, and the shank with the possibility of reciprocating movement in the input window of the cap .

In addition, slots are made on the side surface of the piston element and / or inside the core are longitudinal channels connecting the space under the grill with the cavity of the cap above the piston element.

In addition, at least three longitudinal ribs are made on the lateral surface of the core.

The uniformity of the fluidization of the bed in a wide range of performance control devices of the fluidized bed is due to the introduction of movable cores, regulating the bore sections of the caps and providing a constant aerodynamic resistance of the gas distribution grid regardless of the flow of the fluidizing agent. The implementation of the core in the form of a conjugated piston element in the upper part, moving in the perforated part of the cap, and tapering downward, that is, having a variable cross section, the shank in the lower part, moving in the input window of the cap, allows us to describe the nature of the change in the cross section of the shank with the following dependences (1 ), (2) and (3).

where S is the cross-sectional area of the shank in the plane of the input window of the cap, m ² ;

F _BX - the area of the inlet window of the cap, m ² ;

F _OTB - the total cross-sectional area of the workers, that is, located below the piston element, the holes in the side wall of the cap, m ² ;

k is the design parameter of the cap;

where S _O is the cross-sectional area of the shank in the plane of the input window at the extreme lower position of the core, m ² ;

F _OTB.O - the total cross-sectional area of the working, that is, located below the piston element, holes in the side wall of the cap at the extreme lower position of the core, m ² .

In the particular case when k = 1, from (1) we have:

Due to the nature of the change in the cross section of the liner described above when the flow rate of the fluidizing agent changes, the flow velocities inside the cap are kept at the same level and, therefore, the aerodynamic drag of the grating will remain unchanged. The pressure under the grate is also preserved, since it consists of the weight of the core, related to the cross-section of the piston element, the weight of the liquefied material, referred to the area of the grate, and its resistance. Thus, the constant aerodynamic drag of the lattice provides uniform fluidization of the bed at reduced costs of the fluidizing agent and thereby significantly expands the range of performance control of fluidized bed devices.

The invention is illustrated by drawings, where figure 1 schematically shows a General view of the cap gas distribution grid when placing the core in the lower position, a cut along the axes of the retainer, cap and guide ribs; figure 2 is the same when placing the core in the upper position; figure 3 is a horizontal section aa of figure 1 and figure 2; figure 4 is a horizontal section bB of figure 1 and figure 2.

Additionally, the drawing indicates the following:

- curved solid lines with arrows show the direction of motion of the fluidizing agent in the cap gas distribution grid;

- curved dashed lines show the direction of movement of the fluidizing agent to cool the top of the cap.

The gas distribution cap grill contains fixed caps 1 installed in the plate 2. The caps 1 are provided, in particular, perforated, with several tiers of holes 3. The holes 3 are located in the side walls of the caps 1 at different levels from the plate 2. Inside each cap 1 there is a movable core 4, placed in the cavity of the cap 1 from the side of the input window 5. The core 4 is made in the form of a mating piston element 6 in its upper part and a shank 7 in the lower part. The shank 7 has a tapering downward shape. The piston element 6 and the shank 7 of the core 4 are installed inside the cavity of the cap 1 with the possibility of reciprocating movement of the piston element 6 in the area of the holes 3, and the shank 7 in the inlet window 5. On the side surface of the piston element 6 for cooling the top of the cap 1 are made longitudinal the slots 8 and / or inside the core 4 are longitudinal channels 9 connecting the space 10 under the gas distribution grill with a cavity 11 above the piston element 6. On the side surface of the core 4 there are longitudinal apravlyayuschie ribs 12, for example three edges, for fixing the position of the core 4 and prevent it from jamming.

In addition, on the side surface of the cap 1 mounted latch 13, which are used as supports for the core 4 in its lower position.

The cap gas distribution grill operates as follows.

When the fluidized bed is idle, the initial position in the cap 1 is the lower position of the core 4, at which the lower tier of the holes 3 is open, as shown in Fig. 1. In the lower position, the core 4 is installed under its own weight and rests on the latches 13. With an increase in the flow rate of the fluidizing agent, namely air, the piston element 6 moves up to the area of the holes 3, and the shank 7 up in the inlet window 5. This increases the passage area of the inlet window 5 and the working holes 3, through which the fluidizing agent enters under the layer. At the maximum flow rate of the fluidizing agent, core 4 occupies an extreme upper position, as shown in FIG. 2, and is held in by an oncoming gas stream. When reducing the flow of the fluidizing agent, the piston element 6 moves down in the area of the holes 3, and the shank 7 moves down in the inlet window 5. At the same time, the passage area of the inlet window 5 and the working openings 3 through which the fluidizing agent enters under the bed are reduced. Therefore, the flow rate of the fluidizing agent within the cap 1 does not change when the flow rate of the fluidizing agent changes.

Thus, the use of this cap-type gas distribution grid makes it possible to stabilize the fluidization of the layer material on its surface over the entire range of capacity control, including at reduced costs of the fluidizing agent.

Claims (4)

1. A gas distribution grill containing fixed caps in the plate with inlet windows, provided with holes located in the side walls of the caps at different levels from the plate, characterized in that it is provided with movable cores, each of which is placed in the cavity of each cap from the input side cap windows. 2. The lattice according to claim 1, characterized in that the core is made in the form of a mating piston element in the upper part and a shank tapering downward in the lower part, installed inside the cap cavity with the possibility of reciprocating movement of the piston element in the area of the holes, and the shank with the possibility of reciprocating movement in the input window of the cap. 3. The lattice according to claim 2, characterized in that on the side surface of the piston element there are slots and / or inside the core — longitudinal channels connecting the space under the lattice with the cavity of the cap above the piston element. 4. The lattice according to claim 2, characterized in that at least three longitudinal ribs are made on the side surface of the core.

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