Patent EA-001628-B1 (EA)
Title: Overfeed burner for solid fuel and method of its operation
IPC: F23L9/04
Filed: 1998-06-23
Abstract: 1. Top-feed burner for solid fuel such as chippings, coal or similar with an adjustable output where the burner includes a combustion chamber (2) limited at the bottom by a fire grate (3) that rotates in a horizontal plane, a burner duct (14) connected to the combustion chamber for the non-combusted fumes and means of supplying primary and secondary air characterised in that the fire grate (3) can be adjusted by movement in a vertical direction to decrease or increase the volume of the combustion chamber (2), that in the outlet (12) from the combustion chamber to the burner duct there is a secondary air opening (16) that can be closed, as well as an adjustable draught vent (13) equipped with an adjustable secondary air channel (15) and that a per se known blowing fan (21) that can be regulated is arranged to regulate the feed of combustion air to the burner. 2. Burner according to claim 1 characterised in that the opening of the adjustable draught vent (13) consists of one or more channels (15) arranged to be automatically restricted when the adjustable draught vent (13) restricts the outlet (12). 3. Burner according to claim 1 or 2 characterised in that a stock of loosely lying spheres (10), preferably of differing sizes and of ceramic material is arranged on top of the fire grate (3). 4. Burner according to claim 1, 2 or 3 characterised in that a scavenging air vent (23) is arranged between the blowing fan and the combustion chamber (2) in the flow path of the combustion air between the blowing fan and the combustion chamber. 5. Burner according to claim 4 characterised in that the fire grate (3), the adjustable draught vent (13), the secondary air opening (16), the scavenging air vent (23) and the blowing fan (21) are manoeuvred with the help of motor devices. 6. Burner according to any of the previous claims characterised in that the fuel is supplied to the combustion chamber from above by what is essentially a vertical fuel duct (24) opening above the fire grate (3). 7. Burner according to any of the previous claims characterised in that the fire grate (3) has the form of two or more concentric rings (33, 34) seated at a distance from one another and arranged to rotate with tipping movements of mutually displaced phases. 8. Procedure for the operation of a burner according to any of the previous claims, characterised in that to lower the output of the burner, the speed of the blowing fan (21) is reduced, after which the passage from the combustion chamber (2) to the burner tube (14) is restricted at the same time as the secondary air flow to the combustion chamber's (2) outlet is restricted and the fire grate's (3) speed of rotation is reduced and the scavenging air vent (23) closes. 9. Procedure according to claim 8 characterised in that the combustion air under pressure after the blowing fan (21) is led (29) to a fuel duct (24) for the fuel arranged at the top of the burner. 10. Procedure according to any of claims 8-10 characterised in that the primary and secondary air is pre-heated by scavenging the combustion chamber (2) and the burner duct (14) within a shell (18,19) surrounding the burner.