US 4,165,717 AGranted

Process for burning carbonaceous materials

AssigneeMetallgesellschaft Aktiengesellschaft

InventorsLothar Reh, Martin Hirsch, Per H. Collin, Sune N. Flink

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Abstract

Carbonaceous material, preferably coal or like finely divided solids with a mean particle diameter of 30 to 250 microns, is burned to produce steam in a fluid-bed furnace having a lower free space without internal fixtures and provided above this free space with internal cooling surfaces. A secondary-gas inlet introduces the secondary gas so that the volume ratio of fluidizing gas to secondary gas ranges from 1:20 to 2:1 at a location above the fluidizing-gas and fuel inlets but below the internal cooling surfaces, the gas velocity of the several gases being adjusted so that the mean suspension density of the solids above the secondary-gas inlet is 15 to 100 kg/m.sup.3. Approximately stoidiometric conditions are maintained with respect to the oxygen in the gases introduced and the carbonaceous material and solids are recycled to the bed after being separated from the gases emanating therefrom.

Claims20

Dependent claims

A process for burning a carbonaceous material to provide steam which comprises the steps of:

introducing carbonaceous material into a fluid bed in an upright reactor;
fluidizing the carbonaceous material in said fluid bed with a primary fluidizing gas introduced at the bottom of said bed and a secondary gas introduced into said fluid bed at a level above that at which the primary gas is introduced and above the bottom of the fluid bed, at least the secondary gas containing oxygen;
burning the carbonaceous material with the oxygen;
maintaining the supply of carbonaceous material and oxygen to said fluid bed at distinct proportions;
maintaining the volume ratio of fluidizing gas to secondary gas at substantially 1:20 to 2:1;
controlling the velocity and the volume ratio of said gases to maintain the solids density above the location at which said secondary gas is introduced at substantially 15 to 100 kg/m.sup.3 and with said density decreasing continuously over substantially the entire height of the reactor;
removing thermal energy from said fluid bed by disposing therein, at a level above the location at which said secondary gas is introduced, cooling surfaces in contact with the solids of said fluid bed;
cooling said surfaces with water to produce steam;
maintaining, below the level at which the secondary gas is introduced, a space substantially free of internal obstructions at which said carbonaceous material is introduced;
separating solids from the gas effluent from said bed at the top thereof to collect solid particles;
recycling said solid particles to said fluid bed at a lower portion thereof whereby said fluid bed and the means for separating and recycling said particles constitute a closed solids circuit;
and
removing excess solids from said circuit.

10 more elements

An apparatus for the combustion of a carbonaceous material, comprising:

an upright vertically elongated fluid-bed chamber;
means for introducing carbonaceous material into a lower portion of said chamber;
first inlet means for introducing a fluidizing gas into said chamber at the bottom thereof;
second inlet means for introducing a secondary gas into said chamber at least one meter above said first inlet means and at a level lying above said bottom by up to substantially 30% of the total height of said chamber, at least said secondary gas containing oxygen sustaining combustion within said chamber;
discharge means for removing a flue gas entraining solid particles from the top of said chamber;
conduit means for the circulation of a coolant forming cooling surfaces in a combustion space of said chamber above said second inlet means, said chamber having a substantially unobstructed space below said second inlet means;
and
a separator connected to said discharge means for removing said particles from said flue gas and recycling at least a portion of the removed particles to a re-entry port at a lower part of said combustion space for renewed contact with said cooling surfaces, said re-entry port lying above said second inlet means.

5 more elements

A method of operating an upright fluid-bed reactor provided with inlet means for a fluidizing gas and solid particles near its bottom, a secondary-gas inlet at an elevated level above said inlet means, a channel system in a combustion space above said level for the circulation of a liquid heat carrier, and external conduit means for the recycling of solids from said combustion space to a fluid bed overlying said inlet means with removal of excess solids to the outside, comprising the steps of:

admitting carbonaceous material as part of a mass containing solid particles with a mean particle diameter of substantially 30 to 250 microns together with a fluidizing gas through said inlet means into said reactor at a flow rate sufficient to build up a fluid bed on said bottom beyond the level of said secondary-gas inlet and fill said space with solids in heat-exchanging contact with the heat carrier circulating in said channel system;
admitting a combustion-promoting gas through said secondary-gas inlet into said combustion space, said gases having a combined oxygen content sufficient to burn said carbonaceous material inside the reactor;
and
controlling the feed rates of said gases and of said mass to generate a continuous circulation of solids through said combustion space and said external conduit means while maintaining in said combustion space a substantially constant operating temperature and a mean solids density between substantially 15 and 100 kg/m.sup.3.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 05/842,359Filed 14 Oct 1977 · continuation
Priority: DE 25395465 Sep 1975
Granted: 28 Aug 1979
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

B01J 8/388
Being subject to a circulatory movement only: externally, i.e. the particles leaving the vessel and subsequently re-entering it
F22B 31/0084
With combustion in a fluidized bed: with recirculation of separated solids or with cooling of the bed particles outside the combustion bed
F23C 10/10
Characterised by the arrangement of separation apparatus, e.g. cyclones, for separating particles from the flue gases: the separation apparatus…
F23C 2206/101
Circulating fluidised bed: entrained or fast fluidised bed