LU84927A1 - HIGH TEMPERATURE GAS FLUID FILTERING DEVICE - Google Patents

Description

Γ The invention relates to a device for filtering gaseous fluids at high temperature.

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In many industrial processes such as combustion, gasification of solid materials, heat exchanges or chemical reactions using gases and pulverulent solid materials, it is advantageous to have filtration systems allowing * eliminate all or part of the particles entrained by the gases towards the chimney or the discharge conduits.

The stopped particles are generally accumulated on the: filter or in a hopper which is Attached to it, and are then directed towards the waste or towards a possible use. The filtration efficiency is measured by the ratio of the mass of the particles collected to that of the particles entering the filter. The qualities of the filters are assessed according to the pressure drop which is established between their entry and their exit, according to the temperature level Jus-20 which they can work with, according to the degree of fineness of the dust which they are able to collect and according to their mechanical resistance in service.

Most of the filters which have been developed up to now and which are used in industrial service cannot offer optimum performance simultaneously. Bag filters require utility 2! bonding of very expensive special materials. Electrostatic filters have upper temperature limits that should not be exceeded. Fluidized bed filters cause significant pressure drops.

5 The usual louver filters are the site of harmful turbulence and their performance and mechanical strength. The device for filtering, according to the invention, gaseous fluids at high temperature is characterized in that it has, along a path traversed by the gaseous fluid to be filtered, at least one passage with baffles comprising spaces for retainer constituting dust collecting chambers, the dimensions of the parts being calculated as a function of the characteristics of the fluid to be filtered, so that the flow thereof along the device remains substantially of a laminar nature.

The device advantageously comprises retaining spaces limited on one side by a surface 20 of a baffle element, and on the opposite side, by a secondary plate, preferably substantially parallel to the surface of the baffle element.

According to another advantageous arrangement, the device comprises at least one retaining space bound at its downstream end by a bottom wall possibly permeable to gaseous fluid and connecting the secondary plate to the baffle element to which it is substantially parallel.

According to another embodiment of 350 the invention, the device according to the invention comprises means making it possible to evacuate, other than by gravity, the materials retained and accumulated in the device. These means can be, for example, mechanical means, such as means for applying shock or vibration or pneumatic means.

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According to a preferred arrangement, the device comprises several walls with juxtaposed baffles, leaving between them passages for the flow of the gaseous fluid to be filtered, the device being limited at its two ends by material planes and comprising auxiliary means for approaching and move these planes apart from each other, so as to deform the system of the walls in the manner of an accordion, deformation during which the substantially parallel walls of the chambers tend to deviate from one of the other and / or to tilt one with respect to the other, 1 which promotes the evacuation of the retained materials.

The filter which is the subject of the invention has multiple advantages. Its design in jalou-15 sies duly sized, provided with cubicles or chambers where the dust is collected, its operation in laminar regime, its low manufacturing cost, its high power of dust recovery and the advantageous arrangement of the parts which constitute it. , make it a product whose filtration efficiency is very high for a wide range of particle sizes, and whose temperatures of use are considerably higher than those of conventional filters, which makes it possible to arrange it in a place of gas evacuation pipes where the temperatures are high, with the consequence of being able to relieve the erosion stress of the mechanical equipment for recovering calories or dissipated pressures, equipment which can be arranged downstream of the filter, and be able to recover very hot dust whose sensible heat is also achievable.

The invention will now be described on two embodiments shown diagrammatically in the drawings in which: r 4 - Figure 1 is a longitudinal section of a device according to the invention, limited in this case to a baffle wall installed in a flue; - Figure 2 is a longitudinal section of a device according to the invention, comprising several passages for a gas to be dusted, arranged for example in a general vertical direction.

FIG. 1 shows the essential elements of a device according to the invention. In a flue 1 10 traversed in the direction of arrow F by a hot gas to be dedusted, there is a passage with baffles 2, that is to say a passage delimited by successive parts 2fi, 2'fi, 22 ' ^, 2c ... sometimes oriented in one direction, sometimes in a direction appreciably perpendicular (it may be otherwise) to it. The passage with baffles 2 is completed, over certain parts of its length, corresponding to the different baffles, by secondary plates 2 "a, 2" "b" 2 "c forming with the surface of parts 2 &, 20 2 ^, 2c des chambers 3a> 3 ^ »3C where the dust discharged by the hot fluid which travels the flue in the direction F can accumulate. Chambers 3a> 3b» 3ci etc ... are closed each time at their downstream end by walls 3 * a »31 ^ 3 * c possibly - 25 slightly permeable to gaseous fluid, which are in principle part of the baffle elements 2 * a, 2 * ^, 2 * c,

The elements constituting the flue and the secondary plates 2 "fi, 2" ^ "2" c are made of a material resistant to mechanical and physical stresses at high temperature.

Each chamber has an inlet opening for the gaseous fluid charged with the dusts and these deposit in the chambers as well as on the inclined elements which limit them.

It is essential, according to the invention, that the dimensions of all the elements of the device are calculated so that the flow regime of the fluid to be dedusted is substantially laminar since any turbulence would alter the general efficiency of the device. .

The dust which accumulates little by little in the chambers and on the elements flows by gravity in the channels formed between the successive elements 2'fi, 2 ^; 2 '^, 2Q, etc ... and / or they can-10 be driven laterally by evacuation conduits which we see the mouths in ...

under the action of pressurized gas streams entering said channels through conduits (not shown) opening out opposite the discharge conduits.

The removal of the deposited dust can also be carried out by equipping the device with mechanical means such as means for applying shock or vibration.

FIG. 2 is a section, analogous to that of FIG. 1, of a more complex arrangement, including a system of baffle plates 20, 200, 2000 ... developing for example in the same direction general vertical. The inclination of these plates on the plane normal to the direction of flow is defined by an angle called the direction angle a. This angle is chosen according to the characteristics of the gas to be dedusted. The inclination of the plates on the planes perpendicular to the plane P <j and parallel to at least one of the side walls connecting the chi-cane plates, is defined by an angle ß which can be equal to 90 ° or different from 90 °.

At the level of each change of direction of each of the baffle plates 20, 200, 2000 ... there is the bottom of a dust chamber 30, 300, 35 3000 ..., then 30 ', 300', 3000 ' ... etc. These chambers 6 r are, in the device given as an example here, arranged alternately on one side and on the other of successive planes of the same baffle plate. This regular arrangement in particular ensures a certain homogeneity of the thermal stresses of the system.

As in the previous example, the dimensions of the zigzag passages (here 40.40 ', 40' '; 400,400', 400 "...) traversed by the hot gas to be dedusted, the distances between the elements which limit and, in general, all the dimensions are calculated so that the flow of hot gas takes place substantially in laminar mode.

The system of baffle plates 20, 200, 2000, etc., is limited by the two planes and P2 which can be materialized by mechanical structures (not shown) suitable for being brought together according to the arrows X, X (respectively likely to be distant from each other). During relative movement, the baffle plates (20,200,2000) tend to deviate from the secondary plates (20fi, 200fi, 2000a; 20'a, 200 ', 2000') held fixed. This movement promotes & evacuates the dust accumulated on the plates and in the chambers, which are collected by an appropriate device (not shown). These 25 dusts are hot, their temperature being able to reach several hundred degrees, and this heat can be recovered.

A particularly great advantage of the device according to the invention lies in its ability to be placed in front of the usual devices for recovering the thermal and / or pneumatic energies contained in the gases to be filtered. This is particularly favorable for these recovery devices, from the point of view of their physical or mechanical behavior at high temperature. »R 7

The dust can also be reinjected hot, as an active agent or as an inert agent, in the process from which it originates or in any other process.

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Claims (3)

8 Γ 1, - Device for filtering gaseous fluids at high temperature, characterized in that it has, along a path traveled by the gaseous fluid to be filtered, at least one passage with baffles (2; 40.40 ', 40 * 1; 400,400 *, 400 **) comprising retaining spaces constituting dust collecting chambers (3a, 3b, 3c ï 30,300,3000; 30', 300 ", 3000 '), the dimensions of the parts being calculated as a function of the characteristics of the fluid to be filtered so that the flow thereof along the device remains substantially of a laminar nature. 2, - Device according to claim 1, characterized in that it comprises retaining spaces (3a, 3b, '3c î 30,300,3000; 30 *, 300 ", 3000') limited on one side by the surface of a baffle element (2_, V fi 2b '^ c' 20,200,2000) and on the opposite side by a secondary plate (2 "a, 2" b, 2 "c; 20a, 200 &, 2000a; 20 'a, 200'a, 2000 *) preferably substantially parallel to the over-face of the baffle element 3, - Device according to claims 1 and 2, characterized in that it comprises at least one space for retention limited at its downstream end by a bottom wall (3 ', 3 *., 3') possibly permeable to »25 gaseous fluid and connecting the secondary plate to the baffle element to which it is substantially parallel. according to claim 1 and any one of the following claims, characterized in that it comprises at least one passage (2; 30 40.40 ', 40 "; 400,400', 400") for the fluid to be filtered , limited on both sides by walls s with baffles (20,200,2000) comprising dust chambers according to any one of claims 2 and 3. 35 5.- Device according to claim 4, 9 characterized in that the dust chambers are distributed periodically along the baffled walls, 6, - Device according to claim 5, 5 characterized in that the dust chambers are arranged along a baffle in two, 7, - Device according to claims 4 and 6, characterized in that the chambers arranged along one of the baffled walls (20) alternate with 10 of the chambers arranged along the opposite wall (200). 8, - Device according to claim 1 and any one of claims 2 to 7 "characterized in that it is constituted by several passages (40, 15 40 ', 40"; 400,400', 400'1) limited in part and on the other by baffle walls equipped with dust chambers, the walls common to neighboring passages carrying dust chambers on all their baffles, arranged alternately, one on one side, another on the other. side of the common wall 9, - Device according to claim 1, - comprising a system of baffled walls, 7) uxta-posed, leaving between them passages for the flow of the gaseous fluid to be filtered, characterized in that 25 the system is limited at its two ends by two substantially parallel planes (P ^ Pg), the device comprising auxiliary means for approaching and distancing these planes from one another so as to deform the system of the walls in the manner of '' an accordion, deformation during which the walls are substantially parallel chambers tend to move away from each other and / or to incline with respect to each other, 10, - Device according to claim 9, 35 characterized in that the walls of one side of each 1 ° f dust chamber are kept stationary. 11, - Device according to claim 1, c characterized in that it comprises means allows both to evacuate by gravity the retained materials and 5 accumulated in the device. 12, - Device according to claim 1, characterized in that it comprises means making it possible to evacuate, other than by gravity, or concurrently with gravity, the materials retained and accumulated 10 in the device. 13 · - Device according to claim 12, characterized in that the aforesaid means are means for applying shock or vibration, or pneumatic means. 15 14, - Device according to claim 13 "characterized in that it comprises means for removing the materials retained and accumulated in the chambers and on the walls, using at least one gas jet. 15.- Device according to any one of the preceding claims, characterized in that the dust chambers have their openings to the gaseous fluid which flows in the passages between walls. 16.- Device according to claim 15, characterized in that the direction of travel of the passages by the gaseous fluid, the direction (F) of which is generally vertical, is directed from bottom to top, so that the accumulated dust in these chambers fall by gravity from a level of baffle to the level of lower baffle, and so on to the bottom (Pg) of the device allowing the discharge of the dust accumulated there. 17.- Device according to any one of the preceding claims, characterized in that it is mounted in front of recovery systems such as economizers, exchangers, turbines or other equipment for producing thermal or mechanical energy allowing a possible concomitant recovery-5 the calories contained in the retained materials. in the device. »Vi *