Firing systems

1 .: Moving grate firing

ENERTEC grate firing is based on the system of a moving grate with an air-cooledgrate covering.


In terms of process technology, this means that the material to be fired is placed on the advancing grate and precisely this grate covering in a combustion chamber and moved by the advancing movement of the grate covering in the grate direction to the end of the combustion chamber. In this way, the fuel burns through the heat absorption from this self-sustaining process.


At the end of the grate firing, the ash from the fuel falls into an ash conveyor that is arranged next and is discharged from the combustion chamber.


The grate coating rests on a steel substructure, which is designed as a housing sealed from the outside. The combustion air required for the items to be fired is fed into this housing, the so-calledunderwind zone. The combustion air flows through the grate and is thus fed to the items to be fired.


The feed movement of the grate covering is achieved by the reciprocal movement of successive rows ofgrate bars.


Therows of grate barsare moved via ahydraulic drive.  


Outside the grate furnace housing, a certain number of drive cylinders are flanged to the grate furnace, which transfer their forward and return stroke movements to so-calledgrate trolleysvia a connecting rod.


With their movement, the grate wagons located in the underwind zone in turn drive a certain number of rows of grate bars connected to the grate wagon.


The grate coating consists of individual parts made of heat-resistant cast steel, the so-called grate bars.


These grate bars are placed in the longitudinal direction of the grate in individual rows at fixed intervals on top of one another and on the substructure of the grate furnace.

The horizontal movement of the drive cylinder, the grate carriage and thus the rows of grate bars creates a reciprocal movement of these rows of grate bars to the fixed row of grate bars above and below this row of grate bars.


In the transverse direction of the grate, a defined number of individual grate bars, the row of grate bars, lie next to each other on the substructure. Due to the geometric design of the grate bars lying next to one another, gaps are formed at the joints between the grate bars, through which the combustion air can flow from the underwind zone over the grate covering into the material to be fired.


The necessary cooling of these grate bars is achieved by the relative cold combustion air flowing around them as described in the previous paragraph.



2 .: fuel shaft

The ENERTEC fuel feed chute is a delivery and metering unit that also forms a partition between the furnace and the environment. The fuel feed shaft is formed by a steel housing that is flanged to the combustion chamber face on the feed side of the grate furnace.  


The fuel is fed into the top of the fuel feed shaft by means of a conveyor unit, in which a defined fuel volume is kept constant. This fuel feed, which covers the entire cross section of the fuel feed shaft, forms the seal between the atmosphere and the combustion chamber.


If the upper part of the fuel feed shaft is used for the distribution and intermediate storage of the fuel, it is dosed in the lower part and discharged to the feed zone of the grate furnace. This is done using aslide system.


At the top entry there is aDistribution screwto even out the fuel fill in the shaft. Evenly pouring fuel in the feed chute ensures a safe seal from the atmosphere and increases the fuel supply.


The distribution screw trough is attached to theUpper partof the fuel feed chute flanged and this in turn to thelower part.


The lower part of the fuel shaft is used for metered fuel discharge by means ofdischarge slides. For this purpose, a specific number of slides are arranged next to one another over the entire width of the fuel shaft, which dispense the fuel via a forward and backward movement. Since the width of the fuel feed chute is normally dimensioned to match the width of the grate furnace, an even loading of the grate is guaranteed.


For reasons of system safety and product protection, the lower part of the fuel feed chute is marked with awater-cooled double jacketand top and bottom part with aEraserequipped. In the event of a burn back from the combustion chamber, the extinguishing process is automatically triggered by a temperature monitor. This prevents damage to the product and a possible fire spreading to neighboring system parts.


The delivery characteristics of the fuel feed system are achieved by the forward and backward movement of the fuel slide. The slide is moved by a hydraulic drive.


A corresponding number of drive cylinders are flanged to the housing of the fuel feed shaft, which transfer their lifting movement directly to the slide.



3 .: Injection firing

The ENERTEC injection firing system consists of adosing unit, apneumatic conveyor systemand one or moreinjection burnersfor the combustion of granular and dusty media.


The fuel is fed into the dosing bunker by means of a conveyor unit, in which a defined fuel volume is kept constant. This fuel supply is metered into the pneumatic conveyor system and transported to the combustion chamber. An ignitable mixture of combustion air, conveying air and fuel is generated in the injection burner and burned in the combustion chamber.


The combustion process of the injection furnace initially requires a minimum temperature in the combustion chamber and is then a self-sustaining process.


The dosing bunker serves on the one hand as a fuel storage container and on the other hand as a dosing unit for the individual lines of the combustion system.


Independently of one another, each firing line is discharged from the dosing bunker usingdosing screws. The separation between the bunker and the conveyor system is made using aPressure surge-proof rotary valve.


The fuel is transported to the combustion chamber by means of a pneumatic high-pressure delivery system.


For each firing line aReciprocating compressorsthe necessary delivery volume. In one strand withlow-wear archesand deflections, the fluid is conveyed into the combustion chamber via the injection burner.


Combustion air must also be added to the fuel and conveying air fluid to ensure clean combustion.


This is done via a separate combustion air system withcentrifugal fanper combustion line.


The ENERTEC injection burner is a unit for the mixing and defined management of different material flows before they enter the combustion chamber. The injection burner is made up of various chambers made of special materials and is flanged to the combustion chamber.


The gas-solid mixture of fuel and conveying air and the combustion air are brought together in the injection burner. A flammable fluid is created in which the fuel, due to its composition and flow,low emissionburns.