EP1085283A2 - Installation for the cleaning and burning of shaft furnace exhaust gases - Google Patents

Abstract

Apparatus for cleaning and combusting the waste gases from a blast furnace consists of a system of heat exchangers, a filter (2) and a combustion chamber (5). Apparatus comprises a preheater/cooler (1) for the blast furnace gas connected via an air valve (10) to a cooling air pipe (6) and via an outlet valve (11) to an auxiliary outlet waste gas pipe (8) for hot gases, and also connected to the combustion chamber (5) via a filter (2) and a preheater (3). The combustion chamber (5) consists of two parts (26, 27), the first part (26) forming the combustion zone containing a burner (25) for waste gases, a burner (28) for fuel added and a secondary air inlet (34,) and the second part (27) forming a reaction and cooling zone. The combustion zone has a temperature probe (50) for three temperature regulators (47-49).

Description

The invention relates to a device for cleaning and combustion of shaft furnace emissions, with a heat exchanger, a filter and one Combustion chamber.

Facilities of the type mentioned here for cleaning and combustion of shaft furnace emissions at least two heat exchangers, a filter and a combustion chamber. In such systems the shaft furnace exhaust gases are first a filter supplied in which dust is separated. The filtered shaft furnace emissions occur directly or via one of the preheating of the shaft furnace exhaust serving heat exchanger in the combustion chamber on. The exiting from the combustion chamber Pure exhaust gas then becomes a next heat exchanger, in which the shaft furnace air is preheated. Some systems are equipped with an additional heat exchanger for preheating or cooling the in Filter entering shaft furnace exhaust gases equipped.

The facilities mentioned have a number of Disadvantages on. The shaft furnace exhaust gases contain in addition the solid components also gaseous components, especially carbon monoxide, sulfur dioxide and hydrogen sulfide. At a low inlet temperature of about 100 ° C in the start-up time it can condense the flue gas in the filter and for simultaneous subsequent Corrosion of components of the filter. At higher Temperatures of over 200 ° C cause this to hot shaft furnace exhaust gases a burning through of the Material from which the filter is made. The disadvantageous Arrangement of the mouth of the shaft furnace exhaust into the combustion chamber causes an incomplete and unstable combustion. The small volume the combustion chamber and the incorrect entry position of secondary air leads to an irregular Combustion and increased fuel consumption. The combustion of shaft furnace emissions in the combustion chamber of such devices is not in all operating conditions stable. The system of the so-called hot bypass Furnace air preheater or both preheaters (for Shaft furnace air and shaft furnace emissions) and the secondary supply air into the combustion chamber no trouble-free operation at carbon monoxide concentrations of over 11 - 12% because it is not high Preheating temperature enabled.

Are also disadvantageous in such facilities the vacuum regulation and the quantity regulation of the Shaft furnace air by means of servomotors Control flaps because they are unstable and as a result continuous full load operation of the fan lead to excessive energy consumption.

Explosion protection is also not guaranteed with the help of explosion flaps and / or rupture disks, since their insufficient number and their unfavorable arrangement does not guarantee safe operation.

Other disadvantages of the known systems have their Reason for using unfavorable components. For example, the heat exchanger upstream of the filter two bundles in which the shaft furnace exhaust first from top to bottom and then after it the flow direction has reversed by 180 °, from below flows upwards. This leads to constipation the second bundle with fine dust.

The shaft furnace exhaust filters are usually with bottom brackets equipped discharge screws, which often leads to bearing damage. The filter downstream heat exchangers allow damage or dust clogging not normal Cleaning or no normal exchange the bundle.

The disadvantages just mentioned become essentially by establishing the ones addressed here Type for cleaning and burning shaft furnace exhaust eliminated that a system of heat exchangers, a filter and a combustion chamber having. The facility is characterized by a Preheater / cooler for shaft furnace exhaust from the over an air damper with a cooling air pipe and via a discharge flap with an auxiliary discharge exhaust pipe for hot gases and the at the same time via the route of an exhaust pipe via a filter and a preheater for the exhaust gas is connected to the combustion chamber via the route of a connected discharge line a preheater for the furnace air and the preheater for the Exhaust gases associated with a fireplace, being the combustion chamber consists of two parts, from where the first part forms a combustion zone, in which a burner for exhaust gases, a burner for added Fuel and a secondary air intake open, and of which the second part forms a reaction and cooling zone into which a cooling air inlet opens, the combustion zone with at least a temperature sensor for three temperature controllers is provided.

It is with a view to the thermal conditions advantageous if the preheater of the exhaust gases with a Hot gas bypass is provided.

It is with a view to the thermal conditions further advantageous if the first temperature controller with a servomotor of a valve one Fuel pipe and with a flap one Primary air pipe, the second temperature controller with a servomotor of a flap of the discharge line and a flap of the hot gas bypass of the exhaust gas preheater and the third temperature controller with one Servomotor of a flap of the secondary air inlet connected is.

From the point of view of self-cleaning, it seems advantageous if the preheater / cooler has its own Heat exchanger in the form of a vertically oriented Has tube bundle.

It’s cheap from a hot gas processing point of view, if the preheater / cooler is a mixing chamber having a pipeline for a reactant is provided.

It is favorable from the point of view of maintenance if the Preheater for the furnace air and preheater for the exhaust gases are provided with interchangeable registers, which as Tube bundles are formed.

It is beneficial for functionality if the first one connected to the secondary air inlet Part of the combustion chamber horizontally and second part forming the reaction and cooling zone the combustion chamber is oriented vertically.

In terms of temperature control, it is advantageous that behind the preheater / cooler in the Exhaust pipe a temperature sensor is provided is that with servomotors of the flaps in the pipeline the cooling air and the auxiliary discharge line connected is.

It is used for monitoring the exhaust gas flow in the Shaft furnace advantageous if in the exhaust pipe A Venturi tube is arranged behind the filter is in front of a flap in the exhaust pipe is installed with a pneumatic drive that is connected to the Venturi tube.

It is beneficial in terms of energy savings, if one located in the exhaust pipe Fan and one for moving the furnace air Fan with frequency converters are provided.

It is with a view to the vacuum regulation in the Shaft furnace useful if behind the furnace air preheater a second one in the furnace air pipe Venturi tube is arranged, the one hand with a Pressure sensor and on the other hand with the frequency converter is connected, the pressure sensor in the shaft furnace is arranged and the frequency converter with the venturi tube in the exhaust pipe are connected.

The invention is described below with reference to a drawing explained in more detail. Their only figure shows schematically an exemplary embodiment of the invention.

The figure shows an example of a device for Cleaning and combustion of shaft furnace emissions, which comprises a system of heat exchangers a preheater / cooler 1 for shaft furnace emissions, one Preheater 3 for exhaust gases, a preheater 4 for Air from the shaft furnace. Furthermore, the Set up a filter 2 and combustion chamber 5 on.

The exhaust gases from the shaft furnace are through a Exhaust pipe 9 first the preheater / cooler 1 fed where it either with through the air pipe 6 supplied cooling air cooled or with hot gases supplied through the auxiliary discharge line 8 heated to a temperature of 150 to 230 ° C. become. The cooling air or the hot gas are through a fan 7 promoted by the preheater / cooler. This temperature is for known filter materials suitable and for securing the high Desulfurization efficiency favorable. The flow is the cooling air through the air pipe 6 by a arranged in front of the preheater / cooler 1 Air flap 10 regulated. The flow of hot gas through the auxiliary discharge line 8 is through a discharge flap 11 regulated in the discharge line 8, the with a chimney 44 or with a hot gas outlet is connected from the exhaust gas preheater 3. The control of the air flap 10 and the exhaust flap 11 takes place by means of servomotors 12, 13, in their electrical circuit 130 a temperature sensor 71 is provided, which is in the exhaust pipe 9 is arranged in front of the filter 2. The preheater / cooler 1 has a mixing chamber 15 and one own tube-shaped heat exchanger 14 on, in the exhaust gases flow vertically downwards. Such one Pipe bundle arrangement has a self-cleaning effect, because larger dust particles along the flow along the entire tube bundle length. The secluded Dust is removed from the mixing chamber 15 through a discharge nozzle 61 by means of a drive 63 Dust removal device 62 removed. A effective desulfurization of the shaft furnace exhaust before entering the combustion chamber 5 achieved by means of a reactant, for example Calcium hydroxide, which is powdered by the Pipeline 16 inserted into the mixing chamber 15 becomes. Exhaust gases exit preheater / cooler 1 then through the exhaust pipe 9 into the filter 2, the one with corrosion-resistant baskets 95 and one Screw conveyor 17 is equipped, which only with external, Bearings not shown in the drawing is provided. The screw conveyor 17 is one Electric motor 80 driven. In the lower part the filter 2 is a discharge pipe 18 with built-in dust discharge device 19 is provided, which is driven by a drive 20.

The exhaust gases from the preheater / cooler 1 and the filter 2 then enter through the exhaust pipe 9 the exhaust gas preheater 3, the one with a butterfly valve 22 having hot gas bypass 21 equipped is. The construction of the exhaust gas preheater 3 makes cleaning and replacement of preferably interchangeable registers 90, for example are designed as a tube bundle. On Housing 23 of the exhaust gas preheater 3 is inside, for example insulated with ceramic fibers. From the exhaust gas heater 3, the exhaust gases through the exhaust pipe 9 led into the combustion chamber 5. The exhaust gases are extracted from the shaft furnace by means of a fan 24 in the exhaust pipe 9 between the filter 2 and the exhaust gas preheater 3 is arranged. From the exhaust gas heater 3, the exhaust gases through the exhaust pipe 9 in the exhaust burner 25 of the combustion chamber 5 guided.

The combustion chamber 5 consists of a part 26, which forms a combustion zone which is advantageous provided with a hard lining and horizontal is arranged, and a part 27, which as Reaction and cooling zone is used. The second part 27 is advantageous with an insulation made of ceramic fibers lined and arranged vertically. In the first part 26 open into the exhaust pipe 9 connected exhaust burner 25 and an additional Burner 28 for additional fuel passing through a fuel pipe provided with a valve 30 29 is supplied. Both the exhaust burner 25 and the additional burner 28 are included Primary air supplied by means of an air fan 31 is fed through a pipeline 32, in which one operated by means of a servo motor 46 Flap 33 is arranged. The servo motor 46 controls in addition to the flap 33, the valve 30 of the fuel pipeline 29. In the first part 26 of the Combustion chamber 5 opens out from an air fan 31 coming here and through a branch line 35 introduced a secondary air inlet 34. The Branch line 35 has a flap 36 which of a secondary air servo motor 37 is controlled.

In the second part 27 of the reaction and cooling zone Combustion chamber 5 opens out from one Air fan 38 coming here and through a Pipeline 60 guided a cooling air inlet 38 Pipeline 60 is provided with a flap 41, which is actuated by a servo motor 42 which with a temperature sensor 57 is connected, which in the Drain line 40 behind the combustion chamber 5 is housed. The hot gases from the second Part 27 of the combustion chamber 5 are through the The discharge line 40 is conveyed into the furnace air preheater 4. The hot gases from the oven air preheater 4 are further through the discharge line 40 via a Flap 43 to the exhaust gas preheater 3 and from there to Fireplace or into the atmosphere or over a flap 22 of the hot gas bypass 21 directly to Fireplace or led into the atmosphere. The furnace air preheater 4 has exchangeable registers 90, which is preferably designed as a tube bundle are and an internal thermal insulation made of ceramic fibers exhibit. The two flaps 22 and 43 are actuated by a common servo motor 45. The control of the servo motor 46 of the primary air damper 33 and the valve 30 of the fuel pipe 29, the servo motor 37 of the secondary air damper 36 and the servo motor 45 of the flaps 22, 43 of the discharge line 40 and the bypass 21 ensure three temperature controllers 47, 48, 49, the assigned to the first part of the combustion chamber 5 are in the advantageous common temperature sensor 50 of the three temperature regulators 47, 48, 49 are arranged is. Each of the temperature regulators 47, 48, 49 can also be used with its own temperature sensor 50 be equipped.

The three temperature controllers 47, 48, 49 regulate the Temperature in the combustion chamber 5. The first Controller 47 is connected to the servo motor 46 which the primary air damper 33 and the valve 30 of the Fuel pipeline 29 controls, and to a minimum Temperature set at 800 ° C. The second Controller 48 is connected to the servo motor 45 which at the same time the flap 43 of the discharge line 40 and controls the flap 22 of the hot gas bypass 21, and set to a temperature range of 820-900 ° C. The third controller 49 is in a temperature range set from 840-950 ° C and with the Servomotor 37 connected, the flap 36 in the Secondary air branch line 35 controls. With this arrangement the three temperature controllers 47, 48, 49 a quick response to the change in carbon monoxide concentration possible, making an optimal Combustion behavior under all operating conditions is secured. The temperature sensor 57, which in the discharge line 40 behind the combustion chamber 5 arranged and with the servo motor 42 of the flap 41 connected in the pipeline 60 controls the Amount of cooling air.

For the dust content control is behind the filter 2 in the exhaust pipe 9 a dust content sensor 58 arranged on an optoelectronic or another the dust content at the filter outlet monitoring principle.

The minimization of damage in the event of a possible Deflagration, mostly due to the appearance of Hydrogen in the shaft exhaust gases if there is a leak of the cooling system in the shaft furnace melting zone and / or in the event of a flashback is caused from the combustion chamber 5 with static and also dynamic protective devices reached. Form the static facility Rupture disks or explosion flaps 51 on the Preheater / cooler 1 and arranged on the filter 2 are. The dynamic device forms a Venturi tube 52, which in the exhaust pipe 9 between the filter 2 and the exhaust gas preheater 3 behind the Butterfly valve 53 is arranged, which is a pneumatic Drive 54 by the Venturi tube signal is controlled. To control the furnace air flow serves a second Venturi tube 59, which between the oven air preheater 4 and a not shown Shaft furnace arranged in the furnace air pipeline 410 is. The second venturi 59 is with one Pressure sensor 64, which is used to record a negative pressure is arranged in the shaft furnace, and with a frequency converter 55 of a fan 420 connected. With the pressure sensor 64 is also a frequency converter 56 of a fan 24 in the exhaust pipe 9 connected. The connection is known Way realized what equally for the others Connections apply, for example those of the temperature controller 47, 48, 49, the sensor 71, 57 or the like, which is why it is not discussed in more detail. For the control, it is advantageous to measure all Company sizes using a suitable visualization system map.

The device described works as follows: The shaft furnace exhaust gases are drawn into the preheater / cooler 1 by the fan 24, where they are either cooled with cooling air or heated with hot gas, depending on the temperature measured by the sensor 71. The promotion of the cooling air or the pure exhaust gas takes place with the fan 7. The amount of cooling air or hot gas is controlled by the flaps 10, 11 driven by the servomotors 12, 13, which close or open the air pipe 6 or the auxiliary discharge line 8 in such a way that the Shaft furnace exhaust gas temperature, which is measured with the sensor 71, moved in the range of 150-230 ° C. This temperature ensures that in the mixing chamber 15 of the preheater / cooler 1 by means of a supplied reactant, for example by means of the calcium hydroxide Ca (OH) ₂ already mentioned, the shaft furnace exhaust gases can be desulfurized effectively.

The shaft furnace exhaust gases processed in this way are the exhaust pipe 9 to the filter 2, where Dust components are separated. The severed Dust is removed from the filter 29 by means of a Screw conveyor 17 discharged by an electric motor 80 is driven. The dust content behind the filter 2 is controlled by a dust content sensor 59, where an increased dust content causes damage in the Filters 2 signals. Promotes from the filter 2 the fan 24 the dust-free shaft exhaust gases through the exhaust pipe 9 into the exhaust gas preheater 3, where they are supplied by the hot gas line 4 Hot gases are heated. The exhaust gas flow is in the exhaust gas preheater 3 by means of the Venturi tube 52 measured. If the conveyor speed approximately below twice the rate of combustion sinks, it closes the pneumatic drive 54 having butterfly valve 53 the exhaust pipe 9. The intensity of the exhaust gas preheating is set according to the temperature set by the temperature controller 48 controlled with which the servo motor 45 is connected to the flaps 22 and 43 of the bypass 21 and the discharge line 40 controls, and in such a way that when the temperature is exceeded closed by the flap 43 discharge line and opened by the flap 22 of the bypass becomes. If the set value is undershot Reverse temperature effect. The preheated Exhaust gas is exhausted through the exhaust pipe 9 transferred to the exhaust gas preheater 3 in the exhaust gas burner 25 and there with supplied through the pipeline 32 Primary air mixed. The amount of fuel and primary air volume is controlled by means of the first temperature controller 47 regulated, if exceeded the set temperature by means of the servo motor 46 the flap 33 in the air pipe 32 the primary air and at the same time the valve 30 in the fuel pipe 29 closes. The third temperature controller 49 controls in dependence the secondary air inlet from the set temperature 34 with the help of the servo motor 37, the if the set temperature is exceeded the flap 36 opens. With exhaust gas combustion in the combustion chamber 5, the hot gases by cooling air in the second part 27 of the combustion chamber 5 to an optimal one, using the temperature sensor 57 measured temperature of 600-800 ° C cooled down.

The hot gases generated during the combustion of exhaust gases are through the discharge line 40 in the furnace air preheater 4 introduced, the furnace air through the pipe 410 coming from the fan 420 is fed. In the preheater 4 is furnace air heated to a temperature of approx. 600 ° C.

The hot gases from the oven air preheater 4 are through the discharge line 40 to the exhaust gas preheater 3. The amount of by means of the fan 420 conveyed furnace air and the amount of by means of Fan 24 conveyed exhaust gas, are by the Frequency converter 55, 56 for regulating the power of fans 24, 420 depending on the Specification of the pressure sensor 64 controlled.

The description of the exemplary implementation makes it clear that the mixing chamber 15 from the preheater / cooler 1 can be separated constructively. You can use several filters 2 and several oven air preheaters 4 and / or use exhaust gas preheater 3, without deviating from the principle of the invention would.

The device described is for all types of shaft furnaces can be used, especially for Shaft furnaces, the raw materials for mineral fibers melt.

Claims (11)

Device for cleaning and combustion of exhaust gases from a shaft furnace, with a system of heat exchangers, a filter and a combustion chamber, characterized in that the device has a preheater / cooler (1) for the shaft furnace exhaust gas, which has an air flap (10) with a Cooling air pipe (6) and a discharge flap (11) is connected to an auxiliary discharge gas pipe (8) for hot gases and which is simultaneously connected to an exhaust pipe (9) via a filter (2) and a preheater (3) of the exhaust gas with the combustion chamber ( 5), which is connected via the path of a connected discharge line (40) via a preheater (4) of the furnace air and the preheater (3) of the exhaust gases to a chimney (44), the combustion chamber (5) consisting of two parts (26, 27), of which the first part (26) forms a combustion zone into which a burner (25) for exhaust gases, a burner (28) for added fuel and a Se secondary air inlet (34) open, and of which the second part (27) forms a reaction and cooling zone into which a cooling air inlet (38) opens, the combustion zone having at least one temperature sensor (50) for three temperature controllers (47, 48, 49 ) is provided. Device according to claim 1, characterized in that the preheater (3) of the exhaust gases is provided with a hot gas bypass (21). Device according to claims 1 and 2, characterized in that the first temperature controller (47) with a servo motor (46) of a valve (30) of a fuel pipe (29) and with a flap (33) of a primary air pipe (32), the second temperature controller ( 48) with a servo motor (45) a flap (43) of the discharge line (40) and a flap (22) of the hot gas bypass (21) of the exhaust gas preheater (3) and the third temperature controller (49) with a servo motor (37) of a flap ( 36) of the secondary air inlet (34) is connected. Device according to claim 1, characterized in that the preheater / cooler (1) has its own heat exchanger (14) in the form of a vertically oriented tube bundle. Device according to claim 1 or 3, characterized in that the preheater / cooler (1) has a mixing chamber (15) which is provided with a pipeline (16) for a reactant. Device according to claim 1 or 2, characterized in that the preheater (4) of the furnace air and the preheater (3) of the exhaust gases are provided with interchangeable registers (90) which are designed as tube bundles. Device according to claim 1 or 2 or 3, characterized in that the first part (26) of the combustion chamber (5) connected to the secondary air inlet is horizontal and the second part (27) of the combustion chamber (5) forming the reaction and cooling zone is vertical is oriented. Device according to one of claims 1 or 3 or 4 or 5, characterized in that a temperature sensor (71) is provided behind the preheater / cooler (1) in the exhaust pipe (9), which is equipped with servomotors (12, 13) of the flaps ( 10, 11) in the pipe (6) of the cooling air and the auxiliary discharge pipe (8). Device according to one of claims 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that a venturi tube (52) is arranged in the exhaust pipe (9) behind the filter (2), in front of which in the exhaust pipe (9 ) a flap (53) with a pneumatic drive (54) is installed, which is connected to the venturi tube (52). Device according to one of claims 1 and 7, characterized in that a fan (24) arranged in the exhaust pipe (9) and a fan (420) serving to move the furnace air are each provided with frequency converters (55, 56). Device according to one of claims 1 or 2 or 3 or 6, characterized in that a second Venturi tube (59) is arranged behind the furnace air preheater (4) in the furnace air pipe (410), which has a pressure sensor (64) on the one hand and the pressure sensor (64) on the other Frequency converters (55, 56) is connected, the pressure sensor (64) being arranged in the shaft furnace and the frequency converters (55, 56) being connected to the venturi tube (52) in the exhaust pipe (9).

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