Furnaces – Process – Treating fuel constituent or combustion product
Reexamination Certificate
1998-05-01
2001-03-20
Price, Carl D. (Department: 3743)
Furnaces
Process
Treating fuel constituent or combustion product
C110S348000, C110S216000, C110S245000, C110S266000, C431S007000, C406S173000, C055S340000
Reexamination Certificate
active
06202576
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a process for recycling fine-particle solids, such as coal dust, discharged from a reactor vessel, particularly from a melter gasifier, at a discharging position of the reactor vessel by means of a gas, at a recycling position of the reactor vessel, wherein the solids are separated in a solids separator, particularly a cyclone, subsequently collected in a collecting vessel and from the same are recycled into the reactor vessel by means of a conveying gas while maintaining a difference in pressure between the solids separator and the recycling position and an arrangement for carrying out the process.
From EP-A - 0 493 752 it is known to separate hot dusts from a gasification reactor, such as a melter gasifier, in a cyclone and in order to surmount a difference of pressure between the cyclone and the gasifier recirculate them via a sluice system, namely via a burner. The known sluice system is very expensive in construction, the mechanically operated sluices being moreover exposed to substantial wear by the dustlike solids.
From EP-B - 0 278 287 a process of the initially described kind is known. Here, the solids incurring in the solids separator after separation from the offgas carried out of the reactor vessel are collected in a collecting vessel, wherein between the separator, which is constructed as a cyclone, and the collecting vessel the pressure is lowered to a level equal to the lowest pressure in the solids separator or optionally lower than this pressure by effecting gas exhaustion at a distance from the separator. Although this process offers the advantage that the solids leaving the solids separator can flow into the collecting vessel freely, since between the solids separator and the collecting vessel there is no upward gas flow that would hamper the movement of the solid particles, it still involves the disadvantage that due to the lower pressure offgas from the reactor vessel passes through the cyclone and together with the recycled solids is recycled into the same again, such that processes taking place in the reactor vessel are disturbed or at least are less efficient due to the recycling of already spent gases.
From EP-B - 0 245 268 it is known to conduct the flue gases emerging from a reactor vessel to a cyclone separator, which then recycles separated solid particles into the reactor vessel again. A portion of the solid particles is discharged from the cyclone separator by suction separately from the rest of the solid particles along with flue gas and recycled into the reactor vessel separately. Here, too, in addition to recycling of the solid particles recycling of a considerable portion of the flue gas into the reactor occurs, which in turn increases the gas throughput through the reactor of gas portions that are inert with regard to the reactions taking place in the reactor and entails a lower efficiency of the processes taking place in the reactor.
The invention aims at avoiding these disadvantages and difficulties and has as its object to enhance the functioning of the solids separator and recirculate the solids into the reactor in a stable conveying condition, wherein there is to be avoided on the one hand an additional load on the reactor vessel due to reactor offgas already spent in the reactor in the course of different reaction processes or, on the other hand, if a specific product gas is to be produced in the reactor, a yield loss in terms of product gas.
SUMMARY OF THE INVENTION
In a process of the initially described kind this object is achieved in accordance with the invention in that an additional gas stream independent of the gas stream in the reactor vessel is conducted through the solids separator in a circuit, in the direction of flow of the solids.
The additional gas stream—which is only conducted through the solids separator and after passing through the solids separator is discharged from the solids separator in the exit area of the solids and is conducted to the entry area of the solids into the solids separator again—renders it feasible on the one hand that gas does not flow through the solids separator in counterflow to the passage of the solids and thus cannot hamper the separation processes taking place in the solids separator and on the other hand to enhance the separating efficiency by the existence of a small gas flow oriented in the flowing direction of the solids, wherein, however, recycling into the reactor vessel of gas that has been supplied to the solids separator from the reactor vessel can be reliably avoided.
Preferably, the additional gas stream is produced by means of a pressure gas according to the injector principle, wherein suitably in the exit area of the solids from the solids separator gas for the additional gas stream is sucked off and this gas together with the pressure gas is supplied to the solids separator directly, i.e. by a short route, along with the gas that originates in the reactor vessel and is loaded with solids.
According to a preferred embodiment, in the exit area of the solids separator killing of the particles of the solid matter is effected in a killing space and that the gas for the additional gas stream is sucked out of the killing space to a large extent free from solid particles, whereby it becomes feasible to effect an almost complete separation of the solids and avoid conducting them through the solids separator again by means of the additional gas stream.
To balance the pressure loss on the way from the discharging position up to the recycling position into the reactor vessel, suitably in the collecting vessel that serves for collecting the separated solids, a fluidized bed is maintained, wherein advantageously the freshly supplied solids are charged into the fluidized bed in a lower area of the same—analogously to the action of a siphon.
Preferably, the solids separated in the solids separator are charged into the reactor vessel via a burner, wherein suitably the ash of the solids is agglomerated by combusting the solids. Hereby it becomes feasible to prevent the recycled solids from being carried out of the reactor vessel once again by means of the gases streaming out of the same. The agglomerated ash particles are no longer entrained so easily by the gases streaming upward inside the reactor vessel but will sink to the bottom of the reactor vessel and can be withdrawn there, for example in the molten state or incorporated into a slag.
Advantageously, the solids from the fluidized bed are supplied to the burner by a conveying gas. Hereby it becomes feasible to convert the solids to be recycled into an easily conveyable stable gas/solids suspension by means of the conveying gas and the fluidizing gas that forms the fluidized bed. Hereby the burner is charged with solids in a continuous manner, wherein a high conveying velocity can be achieved at an appreciable pressure loss. This is advantageous inasmuch as pressure fluctuations within the reactor vessel hardly influence the conveying condition.
An arrangement for carrying out the process according to the invention, comprising a reactor vessel, particularly a melter gasifier, a gas discharge duct departing from the reactor vessel and leading to a solids separator, particularly a cyclone, attached to a solids discharge duct conducting the separated solids to a collecting vessel, and comprising a solids recycling duct that departs from the collecting vessel and opens into the reactor vessel is characterized in that a gas circulating duct is connected in parallel with the solids separator provided with a gas injector that sucks off gas from the solids separator and conducts it back into the solids separator, namely in the direction of flow of the solids in the solids separator.
To avoid recycling of solid particles into the solids separator by means of the additional gas stream, advantageously an exit area of the solids from the solids separator is provided with a killing space into which a solids discharge duct of the solids separator opens, the mouth being arranged in the interior of t
Nagl Michael
Schenk Johannes
Stockinger Josef
Ciric Ljiljana V.
Deutsche Voest-Alpine Industrieanlagenbau GmbH
Ostrolenk Faber Gerb & Soffen, LLP
Price Carl D.
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