This Patent Application claims priority to German Patent Application No. 10 2011 101 390.7 filed on May 13, 2011, entitled, “ METHOD AND DEVICE FOR OPERATING A CONVEYOR FOR A COMBUSTION PRODUCT”, the contents and teachings of which are hereby incorporated by reference in their entirety.
The present invention relates to a method for operating a conveyor and to a conveyor for a combustion product. It further includes a method for operating a combustion plant, as well as a combustion plant.
Combustion products (ash, slag and the like) should generally be led away from a combustion plant and be fed to a following process or a collecting tank. The combustion device, which can be designed for a wide variety of purposes, is generally situated directly upstream of the conveyor. The present invention particularly relates, however, to larger combustion installations and large-scale plants which are used for the removal of pollutants and/or for energy extraction. The ensuing combustion products can therefore have very different properties. The focus is here primarily on combustion products which are solid or at least have a high viscosity. The combustion processes here often have in common that the combustion products arise at irregular times and/or in varying quality, so that for following processes a homogenization of the combustion product flow is desirable. Given a slow conveyance of the combustion product, a homogenization can sometimes be achieved. It should further be borne in mind, however, that, particularly if the conveyor is disposed immediately behind the combustion process, due to high residual heat and, in some cases, high thermal capacity of the combustion product, a high heat transfer into the conveyor can take place. In order to avoid this, the conveyor should be operated at a modified speed. In particular, the load for the conveyor, the quantity conveyed from the combustion installation, the cooling behaviour of the combustion product, the supplying of downstream-situated plants with the combustion product, etc., should thus also be better adjusted.
Starting from the above, the object of the present invention is to at least partially overcome the drawbacks known from the prior art. In particular, the object is to define a method and a conveyor with which the combustion product flow is constantly matched to the requirements of following processes.
These objects are achieved by a method for operating a conveyor and by a conveyor having features which are disclosed herein. It should be pointed out that the features which are individually described herein can be mutually combined in any chosen, technologically sensible manner and demonstrate further embodiments of the invention. The description, particularly in association with the figures, illustrates the invention in detail and cites further illustrative embodiments.
A method for operating a conveyor for a combustion product is proposed, which method includes at least the following steps:
As already indicated above, combustion products can be of any nature. In some arrangements, such combustion products are after-products of a combustion operation in the manner of solids. They can therefore, for example, be fine-grained and/or dry in the form of ash, baked and/or moist like slag, and/or can also be present in a mixed form. The conveyor can be any apparatus which is suitable for being temporarily in contact with hot combustion products of this kind, wherein the combustion product, for example, has a temperature (after loading) within the range 20° C. to 800° C., when loaded after the combustion operation has, in particular, a temperature in excess of 500° C., and is transported by the conveyor, for instance, for a period of 20 to 500 seconds.
In step a), the combustion product is transported in a lying manner. By this is meant, in particular, that the combustion product is conveyed in a transverse direction. The combustion product here rests, in particular, on a transport means or transporter (e.g., belt, containers, buckets, subfloor, etc.). In particular, the combustion product can in this phase either be transported lying essentially still on a moved transport means and/or be moved with lying contact over a slowly moved and/or stationary subfloor. This step is executed, in particular, for the transportation of the combustion product from a hotter region into a cooler region.
In the falling transportation of the combustion product according to step b), the combustion product moves in a substantially vertical direction, following (essentially only) the force of gravity. The combustion product can here fall freely and without guidance, or be fed to a specific catching region in a drop shaft, which can be angled occasionally in places or over the entire length. For the controlling of the transport conditions, the combustion product, particularly in a drop shaft and preferably by obstructions, can be impeded in its freefall. The steps including the lying and falling transport can be placed (directly) one after the other in sequence. In other words, this means also that step b) follows directly on step a). Such an embodiment can be provided, in particular, when the combustion products are already fine-grained at the end of step a), for instance with a maximum extent (diameter) of about 250 millimetres, in particular maximally about 100 millimetres.
While the combustion product is falling, it is particularly easily detectable by microwaves. The microwaves are suitable for partially penetrating the combustion product and for being partially reflected therefrom and/or absorbed, so that physical properties of the combustion product are detectable from the (residual) microwave beams arriving at a receiver. Preferably, a (single and microwave-emitting) microwave sensor evaluates the share of the microwaves which are reflected from the combustion product per unit of time.
Hereafter, the detected property is relayed to the control unit (step d)). The measurement result can here be edited, to all intents and purposes to the point where it is directly readable as a data record. However, the measurement results can also be converted only upon reaching the control unit, for example on the basis of electronic signals, into data relating to the properties of the combustion product. These self-edited data, or data already relayed from the microwave sensor, can be analysed in the following step by the control unit (step e)). On the basis of the analysis of the microwave radiation, at least one (physical) property of the conveyed combustion product can be detected. For this, reference tests can be completed and analysed beforehand, which reference tests allow the current microwave radiation to be assigned to a corresponding property. Similarly, it is possible that, apart from the analysis of the microwave radiation, further environmental parameters (microwave scatter, temperature, . . . ) and/or previously known properties of the combustion product (material, temperature, . . . ) are here jointly incorporated. The analysis includes both the comparison with desired limit values and the comparison with requirements, in particular with regard to the conveyor and/or in relation to process variables which are demanded in upstream and/or downstream processes.
As a result, one or more transportation parameters can then be controlled in an appropriately adapted manner in step f). A control circuit for the conveying operation is thus designed in dependence on the measurement results, so that the conveying operation is (automatically) adapted according to corresponding presets. This process is preferably performed in real time. Hence a particularly precise adaptation of the properties of the combustion product, in particular for following processes, is obtained. A particular advantage of this method lies in the fact that the conveyor can be protected from excessive heat influence and, at the same time, the desired physical properties for following processes can be edited.
In a further advantageous embodiment of the method, the combustion product is crushed in the region of a transition from the lying transport to the falling transport. As a result of the crushing in this region, a homogenization of the combustion product not only in terms of its size, but also in terms of its distribution, can be realized in the following measuring section or in the measuring zone (in a drop shaft). Such a crusher, in the case of a combustion product which is already present in a sufficiently small grain size, can therefore also be used as a distributor. The preferred aim of the crushing is therefore not only a uniform grain size of the combustion product, but also an improved detection of the physical properties by the microwaves.
In a further advantageous embodiment of the method, the at least one property of the combustion product which is set to be detected is at least one from the following group:
The stated (physical) properties can be determined both solely through the analysis of the microwave radiation or in combination with measurements in other regions and/or by other sensors. If a volume flow is detected, then statements on the quantity and density of the combustion product are possible, for example. From this, conclusions on the combustion quality and/or the temperature pattern of the combustion product in the conveyor can also be evaluated. This can also be correspondingly achieved through the detection of a mass flow. In the detection of the mass flow, the supplied quality for following processes can also be evaluated. Through the detection of the moisture in the combustion product and/or the ambient air, a quality for following processes and/or also of the upstream combustion process can likewise be determined. Via the temperature, the transport operation, the composition of the combustion product and/or a cooling operation can be analysed. With the determination of the grain size of the combustion product, not only is it possible to assess the crushing, but also to evaluate the quality and nature of the combustion product.
In a further advantageous embodiment of the method, the at least one parameter of the transportation which is set to be controlled is at least one from the following group:
Through the adjustment of the speed of the lying transportation (i.e. the transport speed of the transport means, for example), both the temperature or temperature pattern of the combustion product and the quantity of combustion product can be altered. Hence, in both aspects, an advantageous adaptation of the combustion product quality and combustion product quantity to following processes can be prepared, preferably in real time. Through the adjustment of the cooling of the combustion product, the temperature pattern of the combustion product can in turn be altered, though the speed of the lying transportation does not need to be altered. In this context, however, not only can the cooling quantity be controlled, but also in several types of cooling facilities the adaptation to an optimal cooling is controllable. This can be realized, for example, by means of a cooling from different directions, and inflows of (relatively) cold (ambient) air, water cooling, or in some other conceivable manner. The supply of combustion products from the upstream combustion process can also be controlled, whereby a reduced or increased loading of the conveyor can be obtained. The heat input into the conveyor can hereby also be reduced, for example. The degree of crushing is also dependent on a variety of conditions and, like the previous parameters, can also be adjusted in the interaction between the parameters. In particular, the degree of crushing is of importance to following processes.
In addition, a method for operating a combustion plant is also proposed, wherein, apart from the above-described method, a further step g) is also performed, in which one or more process variables for the operation of a boiler are adjusted by the control unit on the basis of the analysis of the relayed property of the combustion product, the process variable including at least one of the following group:
As already illustrated above, boilers for any type of combustion can be suitable. All types of process-related combustions are controllable, at least via the above-stated process variables.
Through the quantity of supplied combustion air, and/or quality and composition, the duration and temperature of the combustion, above all, becomes adjustable. The course of the combustion is likewise decisively influenced by the fuel quantity. The temperature of the combustion is a very direct quality feature of the combustion, yet constitutes no direct control variable and is adjusted, in particular, via the other stated process variables. The delivered quantity of combustion product has not only a varied influence on the combustion process per se, but also on the following conveying operation and/or the quality and composition of the combustion product itself. It is therefore particularly advantageous to adjust and regulate the combustion process already in the boiler, also on the basis of the measurement data of the microwave measurement in the region of the falling transportation.
By virtue of the method according to the invention, it is possible to provide a combustion product for following processes which is homogenous within small control variations, without thereby subjecting a conveyor to thermal and mechanic overload.
The labelling of the individual steps with a) to g) represents a preferred sequence. It is nevertheless possible for at least a part of the steps to be performed actually simultaneously. Similarly, there is the possibility, in particular, for further processes to be integrated into this sequence and/or for further processes to proceed simultaneously.
In addition, within the scope of the invention, a conveyor for transporting a combustion product is proposed, which conveyor includes at least the following components:
The transport means with drive can be a transport means with which a combustion product can be conveyed in a lying manner, wherein a (transport) speed is adjustable via the (at least one) drive. In the (in the transport direction of the combustion product) downstream drop shaft, the combustion product follows the force of gravity down to a following process or collecting container. This drop shaft can also be provided with falling speed retarding means or retarder (e.g., grille, diversion, constriction, etc.), which influence a falling speed of the combustion product.
In this drop shaft is provided at least one measuring means or sensor for detecting one or more (physical) properties of the combustion product, which with the aid of microwaves enables, in particular, a rapid detection which can be utilized for a real-time control. By suitable measures in the drop shaft and/or on the transport means, it is possible in a preferred embodiment to ensure that the combustion product in the drop shaft passes the measuring means at a substantially constant speed, so that extensive direct and indirect measurement variables can be determined.
It is quite particularly preferred that a plurality of measuring means are arranged in the drop shaft, these being positioned in a (horizontal) plane perpendicular to the drop shaft (distributed, if necessary, evenly over the periphery). Thus the use of three (3) microwave sensors is particularly preferred. The employed plurality of measuring means/microwave sensors can also be constructed or operated differently. Thus different frequency bands, for example, can be used with the measuring means/microwave sensors for measurement purposes.
A suitable microwave sensor can be inserted, for example, in metallic pipes of the drop shaft. As a result of the injection of the microwave, together with the metallic pipeline, a measuring field is generated. The microwave transmitted by the microwave sensor is reflected from the particles of the combustion product and is then also received again. The received signals can be analysed, moreover, with respect to their frequency and amplitude, so that the microwave sensor also works in the manner of a meter. The analysis, which is selectively geared to a predetermined frequency, serves to ensure that only moving combustion products are actually measured.
In the control unit, which receives the measurement signals and/or measurement data from the measuring means, the detected and relayed properties are analysed, as has been described, for example, previously in the method. Based on this and possibly based on further control variables, the control unit is designed to control the conveyor. For this are provided, in particular, the corresponding data lines and/or control lines, which enable a corresponding communication of the components. In particular, such a conveyor allows the transport of combustion product to be regulated in real time.
In a further advantageous embodiment of the conveyor, a crusher is arranged between the transport means and the drop shaft. Such a crusher is particularly suitable for ensuring homogenization of the grain size of the combustion product. At the same time, however, homogenization can also be achieved with the grain size distribution in the following drop shaft portion. A crusher can be realized by a wide variety of crushing means or crushers. For example, this can be achieved by interlocking teeth of gearwheels, grinders or obstacles in the drop shaft. For this, depending on the field of application, a jaw crusher (in which the combustion product is crushed in the wedge-shaped shaft between a fixed crusher jaw and the crusher jaw moved by an eccentric shaft), a roller crusher and/or a grinder (for example for coal) are used.
In a further advantageous embodiment, the conveyor additionally has a cooler, which cools the combustion product at least in the region of the transport means and can be regulated by the control unit. The cooler preferably consists of at least one flap and/or at least one valve between the environment and the transport region (which is encapsulated or integrated in a housing), by which, for example, cooling air is fed to the combustion product during travel in the transport region (preferably in counterflow) with overpressure (by fans, for instance), and/or on the basis of an underpressure prevailing in the transport region. In addition, cooling air or other cooling fluids, controlled by other processes for the cooling, are introduced. The controllability of the cooler can thus also be seen in the fact that the appropriate selection of coolants is made from amongst a selection of different coolers or cooler components, based on the analysis in the control unit, and/or the intensity of the cooling is adapted by the respectively controlled cooler. Thus the cooling can be boosted, for example, if at least one of the following properties is increased: volume flow, mass flow, moisture, temperature, grain size.
In a further advantageous embodiment of the conveyor, the transport means is a troughed chain conveyor or conveyor belt and can be regulated by the control unit. This is constituted by a wet conveyor or, particularly preferably, by a so-called dry conveyor, in which the combustion product is thus transported in the hot state without immersion in a water bath. In a troughed chain conveyor, interconnected troughs, compartments or the like are formed, in which the combustion product is transported. The conveyor belt is constituted, for example, by plates which are driven as one in strung-together arrangement, with the combustion product being deposited thereon. The troughs, plates, etc. of the two transport means can be moved with chain drives or the like.
On a troughed chain conveyor and/or conveyor belt of this kind can also be provided processing means or processors, which effect a processing of the combustion product for the subsequent use of the combustion product. Thus, in the surface of the troughed chains or of the conveyor belt can be provided fins or spikes, for example, which lead to a crushing and more even distribution of the combustion product. Scrapers can also be fitted, which scrapers effect a cleaning of attachments in the region of the troughed chain conveyor or conveyor belt. In the transport means, devices which, in the case of an inclined transport, aid either the maintenance of the current distribution of combustion products on the transport means or, in contrast, cause a redistribution of the combustion product on the transport means, can also be fitted.
In addition, a combustion plant including the conveyor according to the invention and additionally having a boiler is also proposed, wherein the control unit is configured to control an operating resource of the boiler. The nature of the boiler has already been discussed in connection with the method for operating a combustion plant. Such a combustion plant is suitable, in particular, for this method. The operating resources of the boiler are, inter alia, the supply of fuel and combustion air, as well as control means or controller for the venting of combustion products and exhaust gases. For the operation of the boiler, the control unit can additionally be supplied with measurement variables from the boiler, whereby the control unit is in turn capable of undertaking, on the basis thereof, control measures on the conveyor.
By virtue of the devices according to the invention, it is possible to mechanically and thermally protect the conveyor and, at the same time, ensure real-time control of the composition and quantity of the combustion product fed to any following processes.
In principle, the inventive features pertaining to the methods can be correspondingly realized with the devices according to the invention. The devices are therefore particularly suitable and configured to implement the methods. Moreover, the processes and method steps which are represented in connection with the device according to the invention can also be integrated into the method according to the invention (also irrespective of the concrete embodiment of the apparatuses or device components). This applies, for example, to the cooling processes and the regulation of the cooling.
In some arrangements of the method and the device for operating a conveyor for a combustion product, during the conveyance, through the detection and analysis of properties (such as volume flow, mass flow, moisture, temperature, grain size) of the combustion product by means of microwaves, a control of transport parameters (such as transport speed, cooling of the combustion product, supply of combustion product, degree of crushing) is realized. It is herein possible to protect the conveyor thermally and mechanically and, at the same time, to ensure real-time regulation of the composition and quantity of the combustion product for following treatment steps.
In principle it should at this point be pointed out that the invention is focussed, in particular, on the conveyance of combustion products, yet other materials to be conveyed can also, of course, be correspondingly transported. Thus the invention can also similarly be used in the conveyance of, for example, (hot) bulk goods, (wet) sludge, etc. In this respect, for this description of the invention, the “combustion product” can also be regarded as a synonym for these materials.
The invention, as well as the technical environment, are explained in greater detail below with reference to the figures. The figures show particularly preferred illustrative embodiments, to which, however, the invention is not limited. The figures are schematic and denote same structural parts with the same reference symbols, wherein:
In
In
At the transfer of the combustion product 2 into the drop shaft 11, a crusher 13 is interposed, in which the combustion products 2 are crushed into a uniform grain size and homogenization of the grain size distribution is achieved.
The combustion product 2 leaving the crusher 13 is detected by microwaves 3 emanating from the measuring means 12 as in
In
Particularly with regard to the workflow diagrams in
1 conveyor
2 combustion product
3 microwaves
4 control unit
5 transport region
6 combustion plant
7 boiler
8 combustion air
9 transport means
10 drive
11 drop shaft
12 measuring means
13 crusher
14 cooler
15 combustion product supply
16 combustion product metering means
17 drive control line
18 measuring line
19 cooling air
20 transport region temperature sensor
21 TT-measuring line
22 boiler temperature sensor
23 TB-measuring line
24 crusher control line
25 fuel
26 grate
Number | Date | Country | Kind |
---|---|---|---|
10 2011 101 390.7 | May 2011 | DE | national |