Patent Application
20150322356
1. Field of the Invention
The invention is directed to a method for heating a high-temperature Winkler gasifier during the start-up of the gasifier with the use of at least one burner which serves for heating purposes, wherein the gasifier head is assigned a cyclone with a return conduit for returning the particles separated off in the cyclone into the fluidized bed in the lower region of the gasifier, and to a correspondingly equipped high-temperature Winkler gasifier.
2. Description of the Related Art
For the operation of a Winkler gasifier, the system comprising gasifier/cyclone/return conduit must initially be heated. In this case, the fire-resistant masonry is heated to the operating temperature corresponding to the admissible temperature gradient, wherein the stored heat introduced into the masonry serves to bring a fluidized bed material to the temperature required for the ignition process. From a plant operated in practice, it is known, for example, for three gas burners of identical design, each with a power of 0.7 MW, to be used for heating purposes, said gas burners being fitted in the lower region of the gasifier for heating purposes. Here, it is necessary for the gas burners to be mounted when the gasifier is in a shut-down state, and to be dismounted again after the completion of the heating process and before the actual start-up of the gasifier, wherein the required gasifier connectors must be closed before start-up.
A particular disadvantage of this procedure is that the gasifier, once fully heated, cannot be immediately ignited. Therefore, during the dismounting of the burners, which may take, for example, at least one hour, considerable heat losses are incurred. Furthermore, the personnel involved in the dismounting process are exposed to a corresponding level of heat, such that protective equipment must be provided for the personnel.
Since it is sought to operate plants at high capacity, for example to realize a throughput of 160 t/h of mineral coal, gasifier diameters of 3.5 to 4 m, with a gasifier height of approximately 30 m, are necessary. A gasifier of said type would require at least four heating burners; these theoretically required four heating burners would have to be fitted in the cone of the gasifier. Such a requirement however cannot be met in practice.
EP 0 500 517 A1 describes a method for setting in operation a plant for the production of raw iron, wherein, in said method, it is likewise the case that parts of the plant are preheated.
It is an object of the present invention to provide a method by means of which the heating of a high-temperature Winkler gasifier (HTW) is simplified and made substantially independent of the structural size of the gasifier.
With a method of the type referred to in the introduction, use is made of at least one burner which is installed in the head region of the gasifier and which acts downward into the interior of the gasifier, wherein a gas flow is generated in the reverse direction through the return conduit of the cyclone.
With this method implementation, that is to say, with the use of a burner in the gasifier head and a reversal of the flow conditions that prevail during operation in the gasifier, optimum heating of the gasifier is realized with relatively simple means, wherein the need for mounting and dismounting the burner just for the heating process is eliminated.
Refinements of the method implementation according to the invention will emerge from the following description. Here, it may be provided that the burner is operated stoichiometrically or substoichiometrically.
A further refinement consists in that, during substoichiometric operation of the burner, combustion air required in the lower region of the gasifier may be additionally injected through different nozzle planes.
This method implementation described herein makes use of the fact that various nozzle planes are provided in gasifiers in any case, which nozzle planes perform different functions during the normal operation of the gasifier and, in this case, can be used for the introduction of required combustion air.
A further refinement of the invention consists in that a flap may be operated in temperature-regulated fashion in the feed conduit from the gasifier to the separation cyclone. That is to say in particular that, during the starting process, the feed conduit to the separation cyclone can be closed in order to make it possible to realize a correspondingly reversed flow.
In a further refinement, it may be provided that, when the required start temperature of the gasifier is reached, the one (or more) burner provided in the head of the gasifier is (or are) retracted into a region of relatively low particle concentration.
It may also be provided that the burners are supplied with coolant for preventing the formation of particle melt phases, either by virtue of the coolant being conducted directly through the burner head, or indirect cooling being performed.
To achieve the object mentioned above, the invention also provides a high-temperature Winkler gasifier having a cyclone or centrifugal separator which is assigned to the gasifier head and having a solids return conduit from the cyclone into the lower region of the gasifier. Additionally, in the high-temperature Winkler gasifier head there may be at least one burner which acts into the interior of the gasifier.
As already stated above, it is expedient for the cyclone to be functionally separated from the gasifier head during start-up. For this purpose, the invention provides that a shut-off or throttle flap is provided in the connecting conduit between gasifier head and cyclone.
The applicant's application DE 10 2012 004 590, which has not yet been published, presents solutions which describe the flow in the connecting conduit between gasifier head and cyclone.
Here, in a refinement, it is provided that, for the purposes of positioning the burner into regions of relatively low particle concentrations during gasifier operation, the burner (or burners) is (or are) axially movable. It may also be expedient here for coolant to be conducted through the burner for the purposes of preventing the formation of particle melt phases.
The invention is not restricted to a particular fuel type. The one or more burners required for the start-up process may be operable with gaseous, liquid or solid fuels, for example with natural gas, or oil or with corresponding carbonaceous powdered material, to name but a few examples.
The invention will be discussed in more detail below by way of an example and with reference to the drawing which, in the single figure, shows a schematic sectional illustration of a high-temperature Winkler gasifier.
In the figure, the high-temperature gasifier, which is denoted generally by 1, is illustrated in section and in simplified form. The gasifier body composed of fire-resistant masonry and denoted by 2 has, in the lower conical region 2a, the means required for the formation of the fluidized bed. In the head region 2b, there is positioned a cyclone 3 which, during operation, is provided above a feed conduit 5 which can be controlled by way of a closure flap 4, wherein the solids that are separated off are supplied via a return conduit 6 back to the lower fluidized bed in the region 2a of the gasifier.
According to the invention, for start-up purposes, the high-temperature Winkler gasifier is equipped with at least one heating burner 7 in the head denoted by 2b, wherein said burner 7 can, by way of corresponding means which are not illustrated in any more detail and as per the double arrow 8, be moved into the gasifier chamber and, during normal operation, retracted out of said gasifier chamber to such an extent that the burner nozzle is not exposed to fouling or additives. During start-up, the hot combustion products are conducted through the reactor as per the arrows 9. After the required start temperature is reached, the gas flow runs substantially in the opposite direction, which is the case when starting takes place and the high-temperature flap 4 is opened.
To make it possible to additionally influence the fluidized bed and the reaction in the gasifier, air inlet nozzles are provided in the conical region 2a and in the transition region of the fluidized bed; said nozzles are denoted by 10.
In the head region, the arrow 11 indicates the supply of fuel, and the arrow 12 indicates the supply of air.
The described exemplary embodiment of the invention may self-evidently also be modified in a variety of aspects, without departing from the basic concept. For example, as already indicated further above, it is possible for more than one burner to be provided, and the removal or retraction of the burner may if appropriate also take place horizontally rather than vertically, etc.
List of Reference Signs:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2012 112 182.6 | Dec 2012 | DE | national |
This application is the national phase of, and claims priority to, International Patent Application No. PCT/EP2013/075070, filed Nov. 29, 2013, which designated the U.S. and which claims priority to German Application No. DE 102012112182.6, filed Dec. 12, 2012. These applications are each incorporated by reference herein in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/075070 | 11/29/2013 | WO | 00 |
