DE3924076C1 - Mineral material sintering furnace - has burners above and below top run of conveyor belt - Google Patents

Abstract

The belt in the sintering furnace circulates within the combustion space. There are burners distributed right along the belt and right across it. The burness (3) led through a furnace sidewall (11) should be supported by length adjustable devices (25, 26) on the opposite furnace wall (12). The supports (25, 26) are fitted with sensors (27, 29) reporting burner status. The supports pref. comprise a first tube (25) joined to the free end of the burner combustion chamber (31) and a second tube (26) which is led through and joined to the far side wall (12) so the two tubes are movably mounted inside one another. USE/ADVANTAGE - Metal sintering etc. Burner status monitored continuously for even temp. spread using concealed sensors in compact design.

Description

The invention relates to a sintering belt furnace according to the Preamble of claim 1.

From DE-OS 35 24 902 is a sintering belt furnace for thermi processing of contaminated with organic compounds cleaned mineral substances known, in which the before heated materials in the sintering belt furnace and be ignited, causing organic contamination components are oxidatively destroyed.

For this purpose, the feed material is heated in a preheating zone and transported to a burning zone in which it is in a Ignition zone is ignited with several burners, the organic ingredients burned out and in an out Subsequent thermal combustion zone with another burner be delt.

In a cooling zone adjoining the burnout zone the feed cooled and leaves as organic Contaminated mineral material cleaned the Sin terbandofen and can be used as a raw material again in a manuf development process of e.g. mineral fibers will.

A sintering belt is used to transport the feed material det in a substantially closed sinter belt furnace circulates endlessly and from a high temperature permanent, air-permeable grille.  

To preheat the feed or to ignite the ther mixing afterburning are below the sintering belt further burners arranged, the hot gases directly from on the bottom of the sintered belt or on it judge well.

The main advantages of a sintered belt furnace a conventional rotary kiln are that the thermal treatment in a completely gastight closed system is carried out, the Luftfü tion is carried out so that a ge Low negative pressure prevails, causing the entire sinter belt system hermetically sealed from the environment is.

Another significant advantage of a sintered belt furnace is that a short-term shutdown as well possible to start again without additional waiting times is.

The burners of the well-known sintering belt furnace consist of egg ner perpendicular to the longitudinal extension of the sintered belt and over the entire width of the sinter band extending combustion chamber and a burner nozzle, which the hot air from the combustion chamber over the entire Gives width of the sintered belt. The burners are in one Wall of the sintering belt furnace attached and with a blowing material supply and an air supply connected. The other The end of the burner hovers freely in the combustion chamber of the sinter band furnace, because of the intense heat in the fire space of the sintering belt furnace in operation and the corresponding  de Cooling down considerably when parking the sintering belt furnace Changes in length of the metallic burner are the result and thus when attaching the free end of the bren ner on the opposite side wall of the Sinterbando considerable tension would arise.

When operating such a sintering belt furnace in particular for thermal treatment of a resulting from thermal degradation composable and thermally resistant materials It is material because of the targeted temperature control essential along the route of the sintering belt interpretation that the is distributed over the length of the sintered belt arranged burner work reliably and that of each temperature associated with the zone with only slight ab hold softs. In the known sintering belt system he follows the temperature setting in the combustion chamber of the sinter band furnace empirically, without an exact temperature rain and burner monitoring is possible.

Since the heating of the on the sintered belt goods over the entire width of the sintering belt is required to ensure an even thermal treatment of the To achieve feed good, but on the other hand the burners have a considerable weight and from stability green which can therefore only be carried out in a limited length NEN, is also the width of the sintered belt and thus the Sintering belt furnace limits what the throughput of the sinter belt furnace also limited.

The present invention is based on the task reason, a sintering belt furnace of the type mentioned  create the with high stability of the burner and one large width of the sintering belt or the sintering belt furnace monitoring the burner enables and compliance guaranteed a predetermined temperature level.

According to the invention, this object is characterized by the de feature of claim 1 solved.

The solution according to the invention enables a stable support of the burner taking into account the length changes of the burner with temperature changes and the same a significant increase in the combustion chamber of the Sinter belt furnace by widening the combustion chamber and there with the sintered belt.

At the same time, the support device for receiving Sensors for burner and temperature monitoring as well a temperature control is used. It can be advantageous So the sensor device in the support device tion are integrated that interference is switched off protection of the sensor device against aggressive gases during the thermal treatment of contaminated materials and from the high temperatures is given in the thermal treatment.

In an advantageous embodiment of the invention Solution, the support device consists of one with the free end of the combustion chamber of the burner connected first Tube and one through the other side wall of the sinter belt furnace guided second pipe, both pipes against are mutually movable and nested.  

The design of the support device from one another Slidably mounted tubes creates a stable and at the same time space-saving arrangement of the support device tion, the free interior of which is movable stored pipes for arrangement and accommodation as well as Ab shielding of the sensor devices can be used.

Accordingly, a further development of the invention Solution characterized in that the sensor device to record the operating status of the burner from a There is a photocell for flame monitoring of the burner inside the tubes, which are movably mounted one inside the other is arranged.

Because the photocell on the burner combustion chamber aligns and through the pipes against laterally incident Light is protected, precise flame monitoring can be carried out be carried out, both in a continuous Chen operation of the burner a permanent presence of the Burner flames can be detected as well intermittent operation of the burners then each Flame formation can be detected if a parent Control and regulating device switching on the burner reports.

In an advantageous embodiment of the invention Solution is the sensor device for detecting the loading drive state of the burner from one to the other Side wall of the sintering belt furnace guided thermal sensor, the directly on the outer wall of the burner combustion chamber is arranged. The thermal sensor is advantageously sufficient  about half in the combustion chamber along the outer wall into the combustion chamber of the burner so that a tempera door monitoring over a wide range of the width of the Sintered belt can be carried out. Is in the Be rich in which the thermal sensor is located, the ge desired setpoint temperature is maintained, this can be due to are also assumed that also in the Combustion chamber of the burner adjacent the area set temperature is maintained.

An advantageous development of the Lö according to the invention solution is characterized in that the photocell for Flame monitoring for one in front of the flame outlet the burner arranged in the mixing basket is aligned, one from the burner flame outlet cross widening continuously to the combustion chamber has cut, wherein the wall of the mixing basket openings contains, through which secondary air is led.

This enables flame monitoring when the secondary air is fed into the combustion chamber of the burner in a targeted manner, the flame being controlled via the supplied primary air / fuel mixture. The main function of the combustion chamber is to increase or decrease the corresponding amount of air in the case of different hydrocarbons in the material to be thermally treated, which takes place via an O ₂ control of the secondary air. This secondary air control has proven to be particularly important in connection with the composite control of the fuel-primary air mixture for a uniform burnout of the material to be thermally treated.

Thereby, with increasing oxygen content in the combustion chamber of the sintering belt furnace, the supply of secondary air is throttled and if necessary different amounts of energy per Kilogram of material to be treated and the resultant different oxygen values in the sinter belt furnace optimal control of burnout by rain the amount of secondary air supplied to the burners in Ab dependence on the oxygen content in the combustion chamber of the sinter belt furnace performed.

Based on an execution shown in the drawing for example, the idea on which the invention is based are explained in more detail. Show it:

Fig. 1 shows a cross section through a sinter belt furnace;

Fig. 2 shows an enlarged cross section through the combustion chamber of a sintering belt furnace with burners arranged above and below the sintering belt

Fig. 3 is an enlarged, detailed view of a burner according to FIG. 2.

The cross section shown in Fig. 1 by a Sin terbandofen 10 shows the hermetically sealable combustion chamber 100 , which is formed by side walls 11 , 12 and a cover plate 13 and a bottom plate 18 . To avoid heat radiation losses, the inside of the furnace wall is provided with heat-resistant insulation 24, for example a ceramic fiber mat. Optionally, the inner wall of the combustion chamber 100 can also be covered with a steel sheet, so that the heat-resistant insulation 24 is between this combustion chamber cover and the side walls 11 , 12 or the cover plate 13 or bottom plate 18 .

A perpendicular to the plane of the drawing in the manner of a conveyor belt sintering belt 20 is actuated by a drive which consists of a drive motor 14 arranged on a drive bracket 16 , the drive 15 via a sprocket connection 15 drives the axis of a drive drum 21 located in the combustion chamber 100 . The drive drum 21 has a cam gripper belt 23 which engages in the sintered belt 20 . The drive drum 21 is supported by support rollers 22 .

The sintering belt furnace 10 is supported on supports 17 which have additional holding rails 19 for fastening the system at their lower end. An exhaust pipe 41 leads the hot smoke gases ( 40 ) resulting from the combustion to a further thermal treatment or to increase the thermal efficiency mixed with outside air back into the combustion chamber via the burners as primary or secondary air.

Fig. 2 shows an enlarged cross section through the combustion chamber 100 in the range of the sintering belt 20, the feed material is applied to the top thereof. Above and below the sintering belt 20 are arranged on the sintering belt 20 and at predetermined intervals long ent of the sintering belt 20 burners 2, 3 at predetermined Abstän.

The burners 2 , 3 are supplied via a line 81 with fuel and via a line 602 with preheated primary air and have a combustion chamber 30 , a combustion chamber 31 and burner nozzles 34 for the hot air.

As Fig. 2 shows the lower burner 2 is arranged under the half of the material carrying the sintering belt 20 and due to the execution of the sintering belt 20 as an endless belt between the material supporting belt and the return belt is. The distance of the lower burner from the Sin terband 20 is less than that of the upper burner 3rd

In addition, a secondary air line 612 is provided for supplying heated secondary air.

Since the lower burner 2 must be arranged between the upper and joist of the circulating sintering belt 20 to the left on the sintering belt 20 material below the top turn of the sintering belt to heat 20 and because of the limited, available space between the top pull and joist of Sintering belt 20 a direct, ie at a right angle directed to the sintering belt 20 outlet nozzle of the lower burner 2 would lead to a combustion of the material located on the sintering belt 20 Mate rials, the outlet nozzle 34 of the lower burner 2 is at an acute angle on the sintering belt directed 20 so that the emerging from the outlet nozzle 34 of the un direct burner 2 hot gases impinge at an acute angle to the sinter strand 20, that is a greater distance between the exit surface of the outlet nozzle 34 of the lower burner 2 and the sintering belt is provided 20th For better heating of the material on the sintering belt 20 be sensitive, the lower burner 2, preferably 2 at an acute angle on the sintering belt 20 directed outlet nozzles 34 .

In contrast, the outlet nozzle 34 of the upper burner tet court at a right angle to the sinter strand 20, so that the emerging from the upper burner 3 hot gases impinge at a right angle to the sintering belt 20th

As an alternative to this, the upper burner 3 can also have outlet nozzles 34 which are directed at the sintering belt 20 at an acute angle. In the same way can additionally a at a right angle to the Sin Terband 20 directed outlet nozzle 34 side of the ser outlet nozzle 34 arranged offset discharge nozzles 34 are provided which are directed at an acute angle to the sinter strand 20, so that from the obe ren burner 3 emerging hot gases also hit the material located on the sintering belt 20 at an acute angle.

According to Fig. 3 a perforation, instead of slot-shaped outlet nozzle 34 in the outer wall of the combustion chambers 31 at the top and bottom of the combustion chambers 31 of the upper and / or lower burner 2, 3 may be provided. The con figuration of the outlet holes of the outlet nozzles 34 , ie the location of the arrangement of the outlet nozzles 34 in the outer wall of the combustion chambers 31 , their size and mutual distance can be chosen freely depending on the required boundary conditions, so that the hot gases emerging from the outlet nozzles 34 are below at the desired angle and at the desired distance from the sintering belt 20 on the material located on the sintering belt 20 .

As illustrated in FIG. 2, the burners 2 , 3 are fastened in the side wall 11 of the sintering belt furnace 10 and each device is supported in the other side wall 12 by means of a support 25 , 26 . In this way, a stable arrangement of the burners 2 , 3 in the combustion chamber 100 of the sintering belt furnace 10 is ensured, even with long lengths of the burners 2 , 3 , so that the sintering belt 20 can be widened considerably compared to plants known in the past, which means the total throughput of the plant, ie the thermal processing of material applied to the sintering belt 20 per unit time can be increased significantly.

The stable attachment of the burners 2 , 3 in the combustion chamber 100 is ensured even with strong temperature changes, since the support devices 25 , 26 bring about a length compensation, so that even with large temperature differences of more than 500 ° C. the tensioner-free attachment of the burners 2 , 3 in Sinter belt furnace is guaranteed.

Due to the special design of the support devices 25 , 26 , the possibility of accommodating detection devices for monitoring the function and temperature of the burners 2 , 3 is simultaneously created, the con figuration of the support devices 25 , 26 being designed such that the burner also with long lengths 2 , 3 reliable monitoring is guaranteed.

This will be explained in more detail using the detailed illustration according to FIG. 3.

Fig. 3 shows an enlarged cross section through the combustion chamber 100 of a sintering belt furnace 10 in the region of a burner 3 , the combustion chamber 31 is provided on its outer wall with hot air outlet holes 34 , which are arranged in the embodiment shown in the lower region of the outer wall of the combustion chamber 31 are.

The burner 3 is connected to a fuel line 81 and a primary air line 602 . In the fuel line 81 , a control valve and in the primary air line 602 a flap valve ( 39 ) can be arranged, both of which can be connected to a compound controller which regulates the fuel-primary air mixture for a uniform burnout of the material to be treated thermally.

The secondary air is led via a secondary air line 612 to a mixing basket 32 which is arranged in front of the outlet opening of the burner 3 . The mixing basket 32 has a cross-section which widens continuously from the burner outlet opening to the combustion chamber 31 of the burner 3 , ie in the longitudinal section has a frustoconical shape.

The wall of the mixing basket 32 is provided with numerous, in the Darge presented embodiment circular openings 33 through which the secondary air supplied via the secondary air line 612 is supplied to the flame area of the burner 2 . A control valve arranged in the secondary air line 612 can regulate the secondary air supplied to the mixing basket 32 as a function of the oxygen value detected in the combustion chamber 100 with a measuring device 300 .

Depending on the O ₂ value detected in the combustion chamber 100 of the sintering belt furnace 10 and the setpoint set on a gas or temperature controller, the control valve in the secondary air line 612 is adjusted by a motor, so that different amounts of secondary air depending on the gas conditions in the combustion chamber 100 can be set.

The main function of the combustion chamber 31 of the burner 2 is to supply the corresponding amount of air to different hydrocarbons in the material to be thermally treated, increasing or decreasing the amount of air, which takes place via the O ₂ control on the secondary air. This secondary air control has proven in connection with the Verbundre regulation of the fuel-primary air mixture as particularly important for a uniform burnout of the material to be thermally treated.

Both the primary air and the secondary air are highly flue gas-containing and contain a small amount of oxygen, so that the thermal treatment of the material on the sintering band 20 is possible without a large supply of oxygen, which prevents the material from burning out, so that high temperatures are possible are without changing the material so that reuse is excluded.

The burner 3 is fixed on the side of the combustion chamber 30 in one side wall 11 of the sintering belt furnace 10 and is supported on the other side wall 12 of the sintering belt furnace 10 . In this example, the support device consists of two tubes 25 , 26 which are pushed into one another and can be moved against one another, of which one tube 25 is attached to the end face of the combustion chamber 31 of the burner 3 . The pipe 25 can be attached to the end face of the burner 3 , for example by welding.

The other tube 26 is fixed to the side wall 12 of the Sin terbandofens 10 , for example. By welding to the side wall 12 or by a corresponding screwing. The connection of the two pipes 25 , 26 overlaps to such an extent that firm support of the burner 3 on the side wall 12 opposite the combustion chamber 30 is guaranteed.

In the tube 26 connected to the side wall 12 , a photo cell 27 is inserted, which is connected via a line 28 with egg ner control, regulating and monitoring device of the Sin terbandofens. The photocell 27 is aligned on the flame formed in the combustion chamber 30 of the burner 3 as a result of the central arrangement of the mutually displaceable tubes 25 , 26 of the support device.

At the same time, the tubes 25 , 26 serve to shield the photocell 27 from scattering influences, so that the photocell 27 receives only light from the flame of the burner 3 and, in the absence of the flame, a corresponding signal via the line 28 for control - and monitoring device of the sintering belt furnace 10 .

In the same way or in addition, a thermal sensor can be inserted into the nested pipes 25 , 26 and detect the temperature in the combustion chamber 31 of the burner 3 .

In the exemplary embodiment shown in FIG. 3, however, the thermal sensor 29 is arranged next to the support device and extends from the side wall 12 into the combustion chamber 100 of the sintering belt furnace 10 along the outer wall of the combustion chamber 31 in the region of the outlet holes 34 . A corresponding length of the thermal sensor 29 ensures that the temperature in the critical area of the burner 3 is detected, since the temperature naturally drops from the combustion chamber 30 to the opposite end face of the burner 3 .

By appropriate control and regulation of the burner temperature and the detection of the actual temperature by means of the thermal sensor 29 , both the flame temperature and the duty cycle of the burner 3 can be controlled accordingly.

The connection of the support device with the Sensorein devices enables an increase in the stability of the burner 3 while increasing the length of the burner 3, a stable operation and compliance with desired parameters even with a large width of the sintered belt 20th As a result, when the throughput is increased, it is simultaneously ensured that targeted treatment of material to be treated thermally takes place, so that malfunctions can be excluded.

The invention is not restricted in its implementation to the preferred embodiment given above example. Rather, a number of variants are conceivable which of the solution shown also in principle make use of different types.

Claims (6)

1. Sintering belt furnace with a sintering belt that rotates in a combustion chamber, and with several burners distributed over the length of the sintering belt, which extend essentially transversely to the running direction of the sintering belt and over the entire width of the sintering belt, characterized in that the through a side wall (11) of the sinter belt furnace (10) burner run (2, 3) by means in the longitudinal direction of the burner (2, 3) of variable-length support means (25, 26) on the opposite side wall (12) of the sinter belt furnace (10) are supported, and that the Support devices ( 25 , 26 ) with sensor devices ( 27 , 29 ) for detecting the operating state of the burners ( 2 , 3 ) are connected. 2. Sintering belt furnace according to claim 1, characterized in that the support devices ( 25 , 26 ) from a with the free end of the combustion chamber ( 31 ) of the burners ( 2 , 3 ) connected to the first tube ( 25 ) and one through the other side wall ( 12 ) of the sintering belt furnace ( 10 ), which are guided and connected to the side wall ( 12 ), consist of two tubes ( 26 ) which are movably mounted one inside the other. 3. Sintering belt furnace according to claim 1 or 2, characterized in that the sensor devices for detecting the operating state of the burner ( 2 , 3 ) consist of a photocell ( 27 ) for flame monitoring of the burner ( 2 , 3 ). 4. Sintering belt furnace according to one of the preceding and workman surface, characterized in that the sensor devices for detecting the operating state of the burner ( 2 , 3 ) consist of a ge through the side wall ( 12 ) guided thermal sensor ( 29 ) which is directly on the outer wall of the combustion chamber ( 31 ) is arranged trending. 5. Sintering belt furnace according to claim 4, characterized in that the thermal sensor ( 29 ) protrudes about half in the combustion chamber ( 100 ) along the outer wall of the combustion chamber ( 31 ) of the burner ( 2 , 3 ). 6. Sintering belt furnace according to one of the preceding claims, characterized in that the photocell ( 27 ) for flame monitoring of the burners ( 2 , 3 ) is directed to a mixing basket ( 32 ) which extends from the flame outlet opening of the burners ( 2 , 3 ) continuously to the combustion chamber ( 31 ) of the burner ( 2 , 3 ) expand the cross-section, the wall of the mixing basket ( 32 ) containing openings ( 33 ) through which secondary air enters the mixing basket ( 32 ) radially.