EP2095050B1 - Solids distributor for injection plants, blast furnaces and the like - Google Patents

Description

The invention relates to a solids distributor for injection plants, in particular for blast furnaces, with a chamber and a plurality of lancing lines leading away, the chamber having a feed connection for a solid to be distributed, such as ground coal. The invention further relates to a distributor head for such a solids distributor.

For the heating of blast furnaces, burners in power plants and similar facilities is increasingly resorting to the use of ground-solid fuel, in particular coal as fuel. This offers the advantage that over the conventionally used fuel, such as coke or even oil, significant savings in operating costs are possible. In order to enable a uniform feed of the ground fuel into the furnace, a plurality of nozzle lances is usually arranged around the furnace. The ground fuel is supplied to them via single pipes ("lance pipes"). In order to distribute the milled fuel supplied from a grinder, such as a coal mill, or an intermediate conveyor, to the individual lines leading to the lances, a fuel distributor is provided. This has a chamber, which is supplied via a connection of the ground fuel. From the chamber lead a variety of individual lines to the respective lances. A difficulty with this is that in practice there is often an uneven distribution of the ground fuel on the individual lines, whereby different amounts are supplied to the individual lances. This leads to different combustion and thus to uneven heating at the individual combustion nozzles, which is undesirable.

In order to achieve equalization and control of the supply to the individual lances, a coal distributor has become known which has individual quantity controls on the individual lines leading to the lances ( SU-A-1717640 ). A disadvantage of the solution is that it becomes more and more expensive with increasing number of lines, and also often achieved inadequate despite the considerable expense. This is especially true when the ground coal is fed over a relatively long supply line to the coal manifold.

In another approach, a coal manifold is provided having a pressure vessel with a chamber disposed thereunder ( DE-C-3603078 ). In this case, the chamber is divided into a plurality of separate sub-chambers, wherein each sub-chamber one of the lance lines is connected. Furthermore, a bottom connection for supplying carrier gas is provided at each subchamber. With the distribution to the sub-chambers but can not be achieved sufficient equalization of the flow rates in the lance lines, so that must be used to compensate for quantity differences on individual regulations on the lance lines. This is expensive.

The EP 0 0680115 A2 discloses a chamber, similar to a collection chamber, with a, an annular gap in front of the wall opening for connecting lance lines forming displacement body. Powdery material is introduced from a reservoir by means of a screw conveyor in this mixing chamber to be distributed there to the lance lines. So that a uniform distribution is achieved on the lance lines, the conveyed by the screw conveyor powdery material is fluidized on entering the mixing chamber and brought into a vortex-shaped flow.

The invention is based on the object, starting from the last-mentioned prior art to improve a solids distribution of the type mentioned in that a better homogenization is achieved with little effort.

The solution according to the invention lies in the features of independent claim 1. Advantageous further developments are the subject of the dependent claims.

According to the invention is in a solid distribution for injection, especially for blast furnaces, with a chamber and a plurality of leading lance lines, wherein the chamber has a supply port for a solid to be distributed, provided that the chamber is surrounded by a common wall collecting chamber, so that the their connected lance lines are interconnected within the collection chamber, wherein geodetically above the collection chamber, a pressure vessel is arranged, the lower part is formed as a bunker and having an outlet connected to the supply port, and further the upper part is formed as a gas space.

The essence of the invention is to provide the manifold with a collection chamber which is enclosed by a common wall, to which the lance lines are directly connected. The invention has recognized that a significant reason for the unsatisfactory quality of the distribution on the lance lines is a separation of the supplied solid from its delivery gas. As a result, the solid no longer reaches the manifold and lance lines in a homogeneous distribution, resulting in an uneven pulsating mass flow. These inhomogeneities are so large and have such a dynamic that they can often no longer be compensated by the individual regulations used according to the prior art on the individual lance lines; just as little can distributors with individual chambers, to each of which a lance line is connected, provide the necessary compensation.

It is the merit of the invention to have recognized that the negative consequences of demixing can be counteracted only effectively with an improved distribution of raw material in the distributor itself, namely by connecting the lance lines to the common wall, and so relieve the individual lancing regulations or to make them superfluous in the ideal case. It is preferable to make the connections between the lances line connections within the collection chamber as an annular gap. The annular gap causes a tangential flow direction, which is particularly efficient for a balance between the radially directed material flows in the lance lines. In this case, the annular gap can be created in a simple manner, for example by a centrally arranged in the collection chamber displacement body whose outer side is spaced from the circumferential common wall and thus forms an annular gap. Preferably, the displacement body is designed to be upwards, ie in the direction of the pressure vessel, tapered. Thus, its outer jacket forms an inclined surface with respect to the entering into the collection chamber solid and thus contributes even to the distribution on the individual lance lines. In particular, with such a centrally arranged displacement body, the formation of strands, in which a preferred flow channel is formed in the material in one of the lance lines, is effectively counteracted become. Particularly expedient and can be produced with little effort is a conical displacement body.

The invention thus makes it possible to dispense with the complex single-lance control provided in the prior art. In addition, it also allows the supply of the solid over a longer feed line in front of the distributor. In addition, a greater flexibility with respect to the solids supply is achieved, so that the invention is also well suited for upgrading or retrofitting existing plants.

By solid is meant herein fine or coarse-grained. They are preferably those materials which serve as fuel, such as, in particular, coal, for the charging of power plant burners, firing of blast furnaces, chalk chimneys or glass melting furnaces. However, it does not necessarily have to be fuel, but it can also be processed material.

With the solid located in the bunker of the pressure vessel results in a decoupling of the lance feed from the upstream feed. Pressure fluctuations, as they arise in particular by pulsations in the supply to the pressure vessel, so the collection chamber can not reach or only greatly attenuated. In addition, fluctuations in the influx only lead to changes in the solids level in the pressure vessel, and the effluents flowing into the lance lines remain unchanged. It is thus achieved a significant improvement in terms of uniform distribution of the collecting chamber supplied solid in the individual lance lines.

Conveniently, a control device is provided which acts on the solid located in the bunker. By changing the supply, a homogenization can be achieved even under changing load conditions. It is particularly preferred if the control device is a filling height control for the solid. It is designed to keep the filling level in the container as constant as possible. Furthermore, it can be designed to ensure compliance with a minimum fill level during operation. The determination of the actual height is expediently carried out by determining the weight of the entire container, which is mounted on weight measuring cans for this purpose. However, the height can also be measured directly, for example by means of capacitive or microwave sensors.

The control device can also be designed as pressure control. It serves to regulate the gas pressure applied to the supplied solid. In the simplest case, a pressure sensor in the gas space of the pressure vessel is provided for this purpose. Preferably, however, the pressure is used at a lower point, namely at the height of the connection of the lance lines to the common wall of the collection chamber. Thus, a decrease in the solids flow through the lance lines with decreasing level in the pressure vessel, as it occurs in a pressure control on the gas space, avoided. Preferably, the pressure control is connected via a pressure surge-proof filter with the gas space. This ensures a robust operation even in harsh conditions.

Appropriately, a controllable nitrogen feed is additionally arranged on the gas space of the pressure vessel. With her it is possible, the pressure in the pressure vessel or to better stabilize the collecting chamber of the distributor connected thereto, and if necessary to adapt it sensitively depending on the requirements resulting from the operating conditions. In particular, in combination with the pressure control device so a closed loop can be formed, with the greater fluctuations in the supply of the solid, as they can occur especially over longer distances or in mehrflutiger supply can be compensated.

Preferably, the pressure vessel is arranged directly on the collecting chamber. The solid which collects in the lower part of the pressure vessel formed as a bunker can then, directly under the influence of gravity, pass directly into the collecting chamber of the distributor without any further obstacle. Thus, a more reliable as well as more uniform supply is achieved in the collection chamber. Conveniently, the bunker is funnel-shaped. Even with small amounts of solids present in the pressure vessel, such a reliable supply is ensured, whereas with a large amount in the bunker, the filling level and thus the static pressure acting on the supply port only increase at a lower rate. Thus, a further homogenization is achieved. However, it should not be ruled out that the pressure vessel is connected via a downpipe with the supply port of the collection chamber, wherein the downpipe may extend vertically or inclined. It is essential that the pressure vessel is located geodetically above the collection chamber.

To further improve the uniformity can be provided that in addition to the lance lines each have their own individual line control unit is arranged. In order to a particularly high degree of uniformity can be achieved. Single line regulations for lance lines are known per se. Since a high basic uniformity between the individual lance lines is already achieved thanks to the arrangement according to the invention, the conditions are given to achieve a virtually perfect homogenization by means of a particularly sensitive acting single line control. As a further optional or alternative possibility for further homogenization gas supply can be provided, which preferably open at the bottom of the collection chamber. They cause an additional ventilation of the distributor from below, whereby a further system coupling is achieved.

The invention further extends to a distributor head according to the features of claim 19. It is particularly suitable for substructure under existing pressure vessels and thus for easy retrofitting already existing, conventional Feststoffverteilanlagen.

Fig. 1

eine schematische Ansicht einer Zuführanlage für pulverisierte Kohle;

Fig. 2

eine schematische Ansicht eines Kohleverteilers mit einem Druckbehälter gemäß einem Ausführungsbeispiel der Erfindung; und

Fig. 3

eine perspektivische Ansicht eines Verteilerkopfs gemäß einem zweiten Ausführungsbeispiel.

The invention will be explained below with reference to the accompanying drawing, in which an advantageous embodiment is shown. Show it:

Fig. 1

a schematic view of a feeder for pulverized coal;

Fig. 2

a schematic view of a coal manifold with a pressure vessel according to an embodiment of the invention; and

Fig. 3

a perspective view of a distributor head according to a second embodiment.

The invention will be explained using the example of a plant which feeds ground coal as solid fuel to a blast furnace. In the Fig. 1 shown plant for the supply of pulverized coal is designed in two columns. This means that two parallel strands are provided, which are constructed identically to each other. Therefore, only one strand will be described in detail below; the comments apply to the other strand accordingly.

Coal 9 is fed from above into a conveyor 2 via a feed opening 1. The conveyor system can be designed as a known per se twin pressure vessel system.

The milled coal enters a supply line 3, by means of which it is fed to a coal distributor 6 at a blast furnace 99 (shown only for one strand). The line 3 may have a considerable distance, distances over several hundred meters up to one kilometer are possible.

The supply line 3 opens into the upper region of a pressure vessel 4 of the coal distributor 6 which is designed as a gas space 41. Its lower region is designed as a coal bunker 42. From the coal bunker 42, the coal passes into a arranged below the pressure vessel 4 distribution head 7 of the coal distributor. In the illustrated embodiment, in a strand of the pressure vessel 4 is located just above the distributor head 7, absolutely necessary this is not. It suffices an arrangement geodetic over the distributor head 7, wherein the connection can also be made via an inclined downpipe 67, as shown in the other strand. The distributor head 7 distributes the over the pressure vessel 4 fed coal on a plurality of lance lines 90, leading to nozzles 91 on the blast furnace 99.

It will now be referred to FIG. 2 , The pressure vessel 4 has an approximately cylindrical shape in its upper region acting as the gas space 41. In its lower region functioning as a coal bunker 42, the pressure vessel 4 has a conically tapered down shape. In the region of the gas space 41 opens at an input port 43, the line 3, via which the ground coal is supplied. In the upper region of the gas space 41, a pressure regulating device 5 is arranged. It comprises a filter 51, which is connected at its end to the upper vertex of the gas space 41, and whose other end is connected to a discharge line 53. The discharge line 53 includes a control valve 52 which is connected to a control device 59. Furthermore, a pressure sensor 54 and a fill level sensor are provided, which measure the gas pressure or fill level prevailing in the gas space 41 and transmit it as a measurement signal to the control device 59. The level measurement can be done directly, for example via a radar sensor 58, or indirectly via weight measuring cells 58 ', which are arranged in the foundation of the pressure vessel 4 and determine its total weight and therefrom the respective fill level. The illustrated embodiment also shows an optional nitrogen feed. It comprises a nitrogen line 57, which is connected via a control valve 56 to a gas connection 55 in the upper region of the gas space 41 of the pressure vessel. The nitrogen supply control valve 56 is also connected to the controller 59.

At the lower end of the pressure vessel 4, an outlet opening 47 is formed. It is placed directly on a corresponding supply port 77 of the distributor head 7. This results in a direct and continuous connection from the coal bunker 42 in a common collecting chamber 72 of the distributor head 7. The common collecting chamber 72 is surrounded by a single circumferential cylindrical wall 73 in which a plurality of openings 74 is formed. The openings 74 are distributed at equal intervals approximately at half the height over the circumference of the wall 73. They function as connections for lance lines 90, and connect the collection chamber 72 with the blast furnace arranged nozzles 91. Up and down the collection chamber 72 by a bottom plate 75 and a cover plate 76 in which the supply port 77 is formed, pressure-tight. The cover plate 76 is optional and can be omitted if the cross section of the supply port 77 of the distributor head 7 is equal to the cross section of the outlet opening 47 of the coal bunker 42.

Such a variant is in Fig. 3 shown as a distributor head 7 '. Matching elements are denoted by the same reference numerals as in FIG Fig. 2 illustrated embodiment. The collection chamber 72 'is open at the top. It can be seen that a plurality of radial baffles 79 are arranged in the collecting chamber 72 '. They extend in the illustrated embodiment over half the height of the collection chamber 72 ', but may also be higher or lower. They serve to purposefully swirl a flow circulating tangentially in the collection chamber 72 'in order to achieve better mixing. Of course, the baffles 79 also in the in Fig. 2 illustrated embodiment may be provided with cover plate 76.

One recognizes further in Fig. 3 a cone 71 as a centrally arranged displacement body. Its lateral surface bounded by the circumferential wall 73 an annular gap 70. This not only forms a direct flow connection between the openings 74, but gives the flow in the common collection chamber 72 'a tangential component. It is reinforced by the baffles 79 and improves the mixing in the common collection chamber 72 'and thus the distribution of the coal on the lances 90 connected to the openings 74. This arrangement is particularly suitable for preventing or dissolving strands in the flow.

To further promote the promotion and homogenization of coal through the lance lines 90 nitrogen feeds 78 are expediently provided at the bottom 75 of the coal manifold 7. They supply nitrogen gas which serves to loosen and fluidize the coal in the collection chamber 72 so as to more uniformly transport it through the lance conduits 90 to the nozzles 91.

Furthermore, an optional individual line control unit 8 is arranged on the lance lines 90. It comprises a quantity sensor 80 which acts on a control valve 82 via a compact control unit 81. The control valve 82 controls the supply of nitrogen supplied via a feed line 83 into the individual line 90. The individual line control units 8 of the various lance lines 90 can be operated autonomously or synchronized by a common control device (not shown). They are designed to finely adjust the flow of coal through the lance line 90 through a controllable supply of nitrogen.

The operation of the arrangement is as follows. Ground coal is introduced via the line 3 via the port 43 in the pressure vessel 4. In the pressure vessel 4, a segregation takes place, wherein the coal falls in the lower than coal bunker 42 formed area and accumulates there. It has proven useful to form the coal bunker 42 so that it allows a filling height for the coal of at least one meter, advantageously even more. The nitrogen gas used for the supply of coal via the line 3 collects in the gas space 41. It can be discharged controlled from this via the pressure control device 5. For this purpose, the filter 51 is preferably designed shockproof to compensate for pressure surges in the supply of coal or adjustment of the control valve 52. Furthermore, optionally nitrogen can additionally be fed into the gas space 41 via the control valve 56. Via the control device 59, the pressure control device 5 is operated so that the pressure and the density in the pressure vessel 4 are kept substantially constant even with fluctuating mass flow of the supplied via the supply line 3 coal, to a value which is sufficient for further transport to the blast furnace 99th This ensures that the same pressure difference acts across all the lance lines 90 in operation. Strictly speaking, the pressure required for further transport does not correspond exactly to the pressure in the gas space 41, but to the pressure, which is increased by the static pressure of the coal in the coal bunker 42 and the collecting chamber 72, in the common collecting chamber 72 at the level of the openings 74.

The height of the coal in the coal bunker 42 is determined by the controller by means of the weight sensors 58 '. The Control is designed to determine from a weight gain or, decrease the level and thus differences between the fed and discharged coal mass flows. The aim here is to keep the level as constant as possible. When switching off or failure of individual lance lines 90 or fluctuations in the supplied via the line 3 mass flow may lead to changes in the filling level in the pressure vessel 4. Thanks to the separate pressure control, the pressure difference to the blast furnace 99 remains unchanged, so that the mass flows through the lance lines 90 remain constant. Thanks to the thus achieved constancy in terms of pressure and density, the coal from the coal bunker 41 passes evenly into the collecting chamber 72 of the distributor head 7 enclosed by a common wall, whereby a uniform distribution of the coal to the lance lines 90 is achieved with the common collecting chamber 72.

To further increase the uniformity of the coal distribution in the lance lines 90, the individual line control units 8 may be provided. As described above, they detect, by means of the quantity sensor 80, the amount conveyed through the line, and may lead to the adaptation of this amount of additional nitrogen via the control valve 83. As a result, a very even supply of coal to the various nozzles 91 is achieved.

Claims (15)

1. Solids distributor for injection equipment, comprising a chamber and a plurality of lance pipes (90) leading therefrom, the chamber comprising an inlet connection (77) for a solid to be distributed, characterised in that the chamber comprises a collecting chamber (72) that is surrounded by a common wall (73), a plurality of openings (74) being provided in the common wall (73), to which openings the lance pipes (90) are connected, the collecting chamber (72) comprising a central displacement body that, together with the common wall (73), forms an annular gap (70) in front of the openings (74) along the wall (73), and a pressure vessel (4) being provided which is geodetically arranged above the collecting chamber (72), the lower portion of which pressure vessel is formed as a bunker (42) and comprises an outlet (47) that is directly and continuously connected to the inlet connection (77), and the upper portion (41) of which is formed as a head space.
2. Solids distributor according to claim 1, characterised in that the central displacement body is a cone (71) that protrudes upwards out of the collecting chamber (72) in a tapered manner.
3. Solids distributor according to any of the preceding claims, characterised in that a constricted point is provided on the pressure vessel (4) above the inlet connection (77).
4. Solids distributor according to any of the preceding claims, characterised in that a control device (59) is provided that is designed to regulate the pressure on the solid in the bunker (42).
5. Solids distributor according to claim 4, characterised in that the control device (59) is designed to regulate the filling level of the solid.
6. Solids distributor according to claim 5, characterised in that the control device (59) is designed to maintain a minimum filling level of the solid.
7. Solids distributor according to either claim 5 or claim 6, characterised in that the control device (59) is also designed to keep the filling level at a constant value.
8. Solids distributor according to claim 7, characterised in that the control device (59) is designed such that the pressure of the solid at the level of the connection between the lance pipes (90) and the collecting chamber (72) is regulated.
9. Solids distributor according to any of the preceding claims, characterised in that a controllable nitrogen feeder (55, 56, 57) is also arranged on the head space (41).
10. Solids distributor according to either claim 8 or claim 9, characterised in that a pressure sensor (54) for the pressure in the head space is provided that interacts with the pressure-regulating device (5).
11. Solids distributor according to any of the preceding claims, characterised in that the pressure vessel (4) is arranged directly on the collecting chamber (72).
12. Solids distributor according to any of the preceding claims, characterised in that the bunker (42) is funnel-shaped.
13. Solids distributor according to any of the preceding claims, characterised in that separate units (8) for controlling each of the individual pipes are arranged on the lance pipes (90).
14. Solids distributor according to any of the preceding claims, characterised in that gas supply lines (78) are provided that discharge into the collecting chamber (72).
15. Solids distributor according to claim 14, characterised in that the gas supply lines (78) lead into the collecting chamber (72) from below.

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