Cooling of pulverulent solid products.

The present invention relates to the cooled e clamp solid powdered products. It has applications in traitenert of would reflect and in particular in the treatment of uranium ore. In corsécuance,

- now the description which will follow we will present the invention applied to uranium ore, but it will be understood that it may be implemented with any other powdery solid. The uranium ore, since therefore we take as an example the powder, is located during processing, crushed, and then calcined to be freed of organic waste and water quenched. to as a result of these operations is to 550DEGREES^{i C.} t the subsequent step, i.e. the acid treatment, requires tenpérature about 1110 °c.

For such cooling, is exa + UEs a fluidized bed of finely divided solid, said fluidized bed is cooled, the cooled product is in discharges and réalinente fluidized bed hot solid. For cooling the fluidized bed it is known to provide a serpentine embedding therein a fluid recirculation~froidissor gaseous or liquid. It has also proposed to inject within the fluidized bed, at the foot of a chimmey descending in said fluidized bed, directly in contact with the solid, a cold gas pressurized, air most often. The gas provides cooling and causes further expansion at the foot of the chimney, ES clear the product in said chimney. Rather than injecting a cold gas, gold was proposed injecting a gas loaded with a sprayed liquid, such as water, to cool the fluidized bed. Water is vaporized in its injection channel once he enters the fluidized bed and Y ^ lysing the Ni-s expansion, ensured a certain pressure of the injected gas to avoid reîoulemert of the solid in said caral ^ ' injection and for further providing a flow rate of saz in the stack so as to make the runway and to discharge into the chimney. To avoid reioulement the solid in the injection channel, and instead allow the runway in the chimney, the proportion of water is limited, resulting in a reduced refroidisserrent.

The present invention aims at making more effice the refroi ^ issenent to enable on large quantities of products, a lowering of the inportanttenpérature.

It proposed to supply a liquid fluid within the bed to fluidity, keep it liquid juscu ' to the base of a flue stack, injecting said liquid at the base of said chimney, collect the solid kicked and cooled at the top of the chimney and to provide for the renewal of the hot solid.

The liquid is a liquid whose temperature is lower than the temperature of the pulverulent solid content in the fluidized bed.

Advantageously when the temperature of the solid powder is greater than 100 °c, the liquid is water.

To obtain this cooling and this discharge of cooled solid, fluidizing a reactor is used, with a flue stack descending in said reactor, and a fluid inlet opening to the base

the chimney heat insulated on its path within the fluidized bed.

The invention will be now described with reference to the drawings which represent:

- fig. 1, a schematic of the assembly of a cooling installation according to the invention,

- fig. 2, a schematic diagram of a member of the plant that shows nême an alternative embodiment.

The cooling device of pulverulent solid as shown

on the board of the drawings comprising:

- a set-fluidizing and discharging the pulverulent solid J.

- means b of recovery of the pulverulent solid cooled the j

- a circuit c of the cooling liquid.

The assembly has fluidizing and discharging the solid powder consists essentially of a fluidization reactor 1 with a fluidization grid 2 at its base, a pipe 3 fluidizing gas supply,

air in general, through the grid 2 and a shaft 4 for discharging the pulverulent solid, arranged approximately along the vertical axis of the reactor 1, down inside of the reactor proximate the gate 2 and extending confectioneries the other end above the reactor. The reactor 1 receives in its upper part a pipe 5 arrival of the solid to be cooled; it is advantageously bored upper part by port ^ of venting, optionally moni-d * a filter or means recuperated * except dust, the fluidization grid, in the described embodiment, a steel plate is sintered, scattered under the trademark POBAL, the chimney 4 advantageously has its lower end 7 flared frusto-c8ne to facilitate entry had pulverulent solid, and the upper end of a lateral epudenunie 8 as in the embodiment shown in the drawings or a board "limpet" to promote 1' ejection of the pulverulent solid cooled out of the chimney and prevent that there falls, tubing 9 fluid feed cooler, water in the example of uranium ore, enters the draft tube 4 and down within up to the base of the flared end truncated cone. This tubular 9 opens at the base of the truncated cone 7 of the chimney 4 by a

10 or more nozzles fixed or rotating or by a ramp provided '⁵ i holes. A heat insulation 11 surrounds the tube 9 throughout its interior portion to the chimney 4" this heat insulation may be obtained by coating the tubing 9 of an insulating material or shelling said tubular 9 with a conduit 11⁴ years which will circulate a fluid, e.g., air. Advantageously, the piping 11 will also within the fluidized bed in the same region member on the tubing 9'd * water supply and even by the same nozzles 10.

The body of the reactor 1 is provided with fluidizing checks the level of the product it contains. These controls 12 are at least 3 and situated at different heights: control 12a in low position just above the level of exposure of the lower end of the chimney 4 two tests 12b and 12c not far from each other, the upper portion of the body of the reactor 1" the arrival 5 solid product is equipped with a control system in steps of the output 13, operating under the control of three checks level 12a, 12b and 12c; the control 12a controls admission of the product and control 12c off the flow, the control 12b adjusts the flow rate to an average value. The water inlet 9 is provided with two control valves, a valve 14 for modulating the flow of water under the action of a thermowell 15 measuring the temperature R-lactone cooled reaches the upper end of the chimney 4, a valve 1 £>all or nothing, started by the level control 12a cuts off the flow of water as the level of the pulverulent solid cooling descends, enrdessous control of low level 12a and restoring the flow rate when the above low level is reached

The inlets for water, air and product will be - gclirxnfucyéevannes " manual.

The means b of recovery of the pulverulent solid cooled consist essentially ii an expansion tank 17 into which opens the chimney 4" for collecting the cooled product; a dust extractor wheel modules 18 in communication with the expansion tank 17 cuitej of and a conveyor belt 19 located below the expansion tank and the dust separator, for transporting the product to the next processing station.

The expansion tank 17 has a drain hole located in a lowermost portion thereof, said port being provided with a rotary or a siphon eclusor 20 to avoid vapor outlet of the fluid cooler.

The use of the dust extractor 18 following the expansion tank 17 will avoid any loss of product and pollution; the dust extractor will be further equipped with a fan 21. The dust extractor discharges the fine it has trapped onto conveyor 19 through an opening at the lower portion thereof said orifioe is similarly provided with a siphon or a rotary eclusor 22.

After the fan 21 that equips the depoussieror 18 is installed the circuit c of recovery of the cooling liquid. It is -

- eRUs capacitor bank 23? the retention tank 24 with piping 25 arrival of new fluid, and a pump 26 reinjection Li " quide an ignitable injeotionc9 *

The device operates in the manner which will be now described as L ** by Iair fluidization is sent through the gate 2 through line 3. The valve manually intake pulverulent solid to be cooled is open. The solid gradually filled with the reactor. The fluidizing air flow rate is adjusted such that there is fluidizing and that the fluidized bed is dense (about 100 $expansion). The levels of products is equalized in the chimney and into the reactor vessel. As soon as the fluidized bed attained control of low level 12a, produced the runway (it is to say the raising of product in the chimney and escape). Since there is a conduit for heat insulation 11, fébouchant within the fluidized bed, at the foot of the chimney 4, it begins by initiating the runway by sending compressed air into said conduit 11. If, further, the pipe 11 leads to the nozzles 10 water injection, the scavenged air promotes the unsealed to nozzles that could be blocked off by the pulverulent solid. Because of the compressed air, the expansion increases in the chimney 4, raising the level of the solid in said chimney. The solid flows through the bent end 8 into the expansion tank. Hitherto, the cooling is low, only product by contact with air curtain pleat froi - -. The manual valve is then opened for the water in the pipe 9" water flows through the tubing 9t heat insulated by the conduit 11 in which air is circulated, and arrives at the foot of the chimney. It is then injected through the nozzles " O-.

Water participates by its contact cooling the solid and displeased it vaporizes, thereby increasing considerably the cooling and further increasing the expansion ratio and thus further improve the expansion ratio and promote further attempted of the product in the chimney 4 · the cooled product exits through the elbow 8 the chimney and falls in the vessel 17 expanding " the fines are trapped by the depoussieror 18, the surge tank 17 and inescapable depoussieror 18 then delivering the cooled solid on the conveyor 19" the steam is directed through the fan 21 to the battery of condensers 23; the condensed liquid is returned to the low recovery 24~~the AV and recycled water - neu-calve in the aft 2b reinjection. The exit - by the cheudcheud.mirée being initiated, the scavenging air is suppressed in the conduit 11, the product expands, beyond L¹ necessary expansion for fluidization is not provided anymore and steam water formed at the base of the goosefoot-to-mined. Since the heat insulating aging of the pipe 9 is only performed by coating with insulating materials or by a double wall cladding, without of openings through which said sheath would result at the chimney-tied, the priming operation is carried out with water, to flow first reduced, and then progressively more inportant when the temperature of the bed is small compared to the temperature of vaporization of water, directly with a large flow rate when the temperature difference is large.

The injected water absorbs the calories of the solid by engagement initially, and then evaporate. As soon as the level in the reactor reaches the control medium 12b, the flow rate of product slows down, and then automatically adjusting the product level is carried out by levelling control 12a, 12b and 12c coupled with the flow control valves. The flow of water is greatly accelerated fits - ^ lemert automatically by the valve 14 for that remains constant temperature of cooled solid, temperature detected by the probe 1d₀

If the level of powdery product into the reactor vessel 1 were to descend, due to a shutdown of upstream facilities, to a. level lower than the level control 12a, the water flow would be cut off panel action on the valve 16 coupled to said level control 12a} this shall the " matte gold ion of sludge in the bottom of the reactor.

The means b and c will be insulating panel to avoid premature intercondensations ^ d-e, the formation of sludge in the vase or development and ion and - ' years the frosted " sieror.

In alternative embodiments, water will not be sent through a branch pipe 9 within the chimney 4" simple by a manifold 27 arriving straightforwardly the bottom of the reactor and opening flush with the bottom~~7 U-flared oth of said chimney. In these implementations, the heat insulation of the pipe 27 is formed by the conduit 3 fluidization air outside the reactor 1 and inside, the length of tubing 27 through the solid expensive - - ' being very reduced, water will not be vaporized prior to being injected into the fluidized bed through the nozzle 10.

Advantageously can return^{the X} appending to the tubular oujours 27 water supply, an air supply line leading to the same nozzle 10.

In the event of large cooling units, the chimney 4 will not be single, but a series dd.e chimneys IRDs' provoking, taking all birth within the same fluidized bed and opening into a s "=UL or in more expansion absorbing vessels. Each flue will have its own water inlet 9 and possibly its own feed air or the contrary,

it willwill r.ourra concern - one water bar and optionally air commone, intra * leakage through the bottom of the reactor and having ports of infection * relaxed®? at the base of each chimney. Infection of air, together with water to the " base of the cherrirée, not strictly necessary pregnant yesterday still present

5 advantages: it facilitates startup by opening out the nozzles which would have

could be obstructed by the powdery product in ignition and creating a takes-off; and d * on the other hand it allows monitoring the humidity to avoid in the expansion tank and the dust separator condensations which would form slime with the powdery product,

The O! measurements with cooling equipment of different sizes have been made; the solid pulvérulert cooling was a sand of fine grain size, such that 1' set of the product has a particle size less than 300/u bare and has a particle size less than 50 $0/u ^ *

thus for large appliances having a reactor diameter Comoros

5 between 800 and 1000 cm, a chimney 350 c® of diameter, in ervo-to-a-hill > fluidizing air to 100 nsec/hour, by injecting 3_} 75 tons of water per hour, is cooled 20 tons of sand per hour of 550 to 110 °c.

the tests focus on hardware semi-major conpte make comparable results: thus with a. reactor 50 cm in height, of 20 cm O diameter, a chimney of 4 cm in diameter and 250 cm in height, by re * 2 kg of sand froidit 550 to 200 °c per minute by injecting per minute a half liter of water at the base of the chimney to 5 cm above the grid ^ e of fluidization.

Or else, with 350 cm height of chimney, cooling to

5 sand 4 kg per minute 510 to lé0°0 3/4 by injecting a liter of water.

The installation will be operable without checks on the level 12b and 12c the product level being according to the flow rate, said flow rate êtent itself determined by the temperature of the exiting product *

Advantageously, the orifice 6 of venting the reactor üuidiestier CPR "ly connected I-RR-ICR mass. - - - ' URs τ" ITs R.^WITH a T -. - product loss and pollution