FR2493961A1 - PROCESS AND BURNER FOR THE PRODUCTION OF A ROTARY FLAME OF PULVERIZED COAL - Google Patents

Abstract

The invention relates to the production of a rotating coal-dust flame in greatly cooled combustion chambers of industrial heat-generation installations. The aim of the invention is to extend the area of use of solid fuels to industrial heat-generation installations which have thus far used fuel oil and gas firing systems. The task consists in the production of a suitable process and a burner for greatly cooled combustion chambers, with which high reaction rates and thus short burn-out times can be achieved. The task is achieved by supplying a combustion chamber with air at ambient temperature by means of an axial primary air flow loaded with coal dust and tangential secondary air flows. After ignition, the flame burns without support firing. It is advantageous that the burner according to the invention can subsequently be arranged on small steam generators or the like.

Description

 The invention relates to a method and a burner intended for the production of a rotary pulverized coal flame in highly cooled combustion chambers of industrial thermal installations, preferably of small: steam generators.

 It is known that, in order to produce and maintain a stable pulverized coal flame in restricted combustion chambers where the combustion path is short, which amounts to saying that the combustion time is short, the maintenance of the reaction temperature by means of auxiliary ignition agents, in the form of refractory linings, bridges, conduits, interposed devices, etc., (for example German document OS 27 35 519).

 the drawbacks of the known methods and installations reside in that they require large combustion chambers and / or interposed devices and / or: accessories embedded in the combustion chamber, liable to wear. These measures do not allow 'at great cost or even do not allow their use in steam generators with tubular hearth in particular if their power is low.

 On the other hand, burners and processes are known for the production of rotary flames for restricted and highly cooled combustion chambers which, however, can only be put into service with fuel: gaseous and liquid.

 The object of the invention is to broaden the field of use of solid fuels up to industrial heat production installations in preference to steam generators with a tubular hearth, which hitherto have been supplied with heating oils and combustible gases and in particular to substitute pulverized solid fuels for heating oils and gases, in existing heat production installations.

 To this end, the invention proposes to provide a method and a burner intended for the production of rotary pulverized coal flames with high reaction rates and short-term combustion, for narrow and strongly cooled combustion chambers, while feeding them with a wide variety of pulverized fuels.

 This result is obtained by a process characterized in that the combustion air is supplied to the combustion air at ambient temperature on the one hand, in the form of an axial primary air flow, fuel charge balanced powder with a moisture content qt'J- can go up to the limit of the possibility of transport and a grain size which can go up to that of a coarse dust, and on the other hand in the form of secondary air tangentially directed, thereby forming a short, regular rotating flame, of high radiation intensity, with an internal recirculation zone 9 with combustion taking place without a flame support, the thermal power being adjustable by modifying the speed and / or atomized fuel charge of the atomized primary fuel air mixture.

 the butter according to the invention is constituted by an inner tube without accessory devices inserted for the mixture of primary air and pulverized fuel and by an annular channel surrounding this tube comprising a constriction and a device for guiding the secondary air which is connected to the combustion chamber, a diff'eur. On the annular channel is mounted, the cfjjo of the arrival of this secondary air, a connection with a register of a known model.

 The guiding device has accessories for guiding the air tangentially at an acute angle to the outlet plane. According to the invention, the burner can be mounted after the fact in one piece with a fixing flange on the combustion chamber of an already existing steam generator in place of an oil or gas burner.

 This burner is; supplied by a tubular pipe with a primary air-atomized fuel mixture, and by another pipe with db secondary air.

 Secondary air flows through the device's high-speed guide device into the combustion chamber, causing a circular current to form with a very clear interior recirculation area, so that it produces an intimate mixture between the fuel and the combustion air. As a result, the speed of the combustion reaction rises, so that a compact, rotating, pulverized coal coal is formed, with high energy density and short combustion times.

 The invention is explained below using the example of a burner with reference to the accompanying drawing.

 Inside the burner is the tube i intended to supply the primary air-atomized fuel mixture, which is prepared in an air stream by means of a member which is not shown.

 The secondary air is supplied to the guide device 4 through the annular channel 2 surrounding the tube 1, passing through a narrowing 3. The secondary air arriving tangentially, leaving the guide device 4, arrives, by the diffuser 5, in the combustion chamber. The adjustment of the quantity of secondary air takes place by means of register 6.

The tube i is fixed to the annular channel 2 by means of the flange 8. The entire burner is fixed by means of the fixing flange 7 to the combustion chamber of a steam generator of a known type and which is not shown.

 By means of the solution proposed by the invention, it is possible to use, in automated operation, a fuel atomized in industrial heat production plants of fault power. It is particularly advantageous here that it is possible to convert, subsequently, heat production installations of this type of consumption of oil or gas as fuel, into installations of the consumption type of pulverized solid fuel.

Claims (4)

 10) Process for the production of a rotary flame of pulverized coal in a steam generator preferably with a tubular flame, characterized in that combustion air is supplied to the combustion chamber at ambient temperature of a part in the form of an axial primary air stream loaded with solid fuel-powder having a moisture content which can go up to the limit of the possibility of transport and a grain size which can go up that of coarse dust and on the other hand in the form of secondary air tangentially directed, thus forming a short and regular rotary flame whose radiation intensity is high, with an internal recirculation zone, combustion taking place without a flame support, the thermal power being able to be adjusted by modifying the speed and / or the charge of atomized fuel of the primary air-fuel atomized mixture.  2) Pulverized fuel burner for the application of the method according to claim 1, characterized in that it is constituted by an inner tube (1), without accessories inserted, for a mixture of primary air sprayed atomized and by an annular channel (2 ) surrounding the tube (1) comprising a narrowing (3) and an air guiding device (4) intended for the secondary air to which a diffuser (5) going towards the combustion chamber is connected and which is mounted a fitting (8) containing a register of a known type (6) being mounted on the annular channel (2).  30) A pulverized fuel burner according to claim 2, characterized in that the air guide device (4) has inserts intended to guide the air tangentially at an acute angle relative to the outlet plane.  40) pulverized fuel burner according to any one of claims 2 and 3 characterized in that the bradeur can be mounted and fixed in one piece, with a fixing flange (7) on the combustion chamber of a steam generator already existing.