Arrangement for gasifying fuel

An arrangement for gasification of fuels within the range from fine grain fuel to dust shaped fuels, in a dust cloud with gas comprises a gasification reactor provided with at least two burners, a supply container for accommodating a fuel, a distributor connected to the supply container for receiving the fuel from the supply container, and a plurality of conduits connected with the distributor and supplying the fuel from the latter to the burners, the conduits having a different geometrical parameter including at least one of a length and a direction.

BACKGROUND OF THE INVENTION 
The present invention relates to an arrangement for gasifying fuels. More 
particularly, it relates to an arrangement for gasifying fuels within the 
range from fine grain to dust-like fuels in a dust cloud with oxygen 
and/or air and in some cases water steam in a gasifying reactor which is 
provided with at least two burners located in a plane in the side wall of 
the reactor. 
The autothermal gasification of the fine grain-dust-like fuels with an 
average grain size from approximately 50 um in the dust cloud with oxygen 
and/or air and in some cases with water steam has been known for a long 
time under the name Koppers-Totzek process. In accordance with this 
process a fuel to be gasified and the reaction medium are blown through 
the burner into an empty gasification reactor and converted there into a 
crude gas by partial oxidation and temperatures above the slag melting 
point. The crude gas can be processed to synthetic gas or fuel gas. When 
this process is performed under normal pressure, the fuel can be supplied 
to the burners through a screw conveyor which allows a sufficient quantity 
regulation. The fuel is first supplied by the screw conveyor first to a 
so-called mixing head, and from there it is blown by the stream of the 
gaseous or vaporous reaction media through the burner head into the 
gasification reactor. More recently there has been a tendency to develop 
this process further so that the gasification can be performed with 
increased pressure between 10 and 100 bar, preferably between 25 and 45 
bar. The pressure version of the Kopper-Totzek process is identified as 
PRENFLO process. In this case the screw conveyor is hardly suitable for 
the transportation of the fuel to the burners. Instead, a pneumatic 
conveyance with preferably inert conveying gas is utilized. 
The gasification in the dust cloud requires an exact arrangement of the 
fuel and reaction medium. Gasification reactors with high throughput are 
provided for example with two or more burners. For an optimal operational 
result, a fuel supply of a uniform quantity and uniform shape must be 
provided to all burners of the gasification reactor. In normal case the 
deviation region of the supply stream density during the fuel supply must 
be only approximately .+-.2%. 
For solving this problem it has been proposed in the German document No. 
DE-OS 3,509,221 to connect each pair of the burners of a gasification 
reactor with a common fuel supply device by symmetrically arranged 
conduits. This solution requires satisfying certain symmetry requirements 
with respect to the positioning of the fuel supply device and the conduit 
path to the gasification reactor. With two or more gasification burners 
also additional fuel supply devices are required in this case. These 
requirements lead to respective investment and operation costs and do not 
provide an optimal solution of the above mentioned problem. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an 
arrangement for gasification of fuels, which avoids the disadvantages of 
the prior art. 
More particularly, it is an object of the present invention to provide an 
arrangement of the above mentioned type in which the fuel supply of a 
uniform quantity and shape to all burners of a gasification reaction is 
insured. 
It is also an object of the present invention to provide such a uniformity 
with low apparatus expenses and to permit a conduit path for the fuel 
supply to the burner within wide limits. 
In keeping with these objects and with others which will become apparent 
hereinafter, one feature of the present invention resides, briefly stated, 
in an arrangement for gasification of fuel in which all burners of a 
gasification reactor are supplied from a single supply container through a 
distributor, and the conduits for the fuel supply from the distributor to 
the individual burners have different lengths and/or different directions 
(paths). 
When the arrangement is designed in accordance with the present invention, 
contrary to the teaching of the German document No. DE-OS 3,509,221 the 
symmetrical conduits for the fuel supply to the burners of the 
gasification reactor are dispensed with. The conduits can be of different 
lengths, and/or different directions (paths). Thereby operational 
requirements as well as requirements for maintenance and repair can be 
satisfied in an optimal manner. 
In accordance with another feature of the present invention, different 
pressure losses due to different lengths and/or directions of the conduits 
(number of deviations) can be equalized by special means provided in each 
conduit. These means can be formed as throttles arranged in the conduits. 
Instead of the throttles, also regulating valves of a conventional design 
can be utilized. In the conduit in which a maximum pressure loss is 
expected, such means can be dispensed with. 
It should be emphasized that in the inventive arrangement all burners of 
the gasification reactor are supplied with fuel from an individual supply 
container. This is especially advantageous when the gasification reactor 
has more than two burners. With modern, large installations corresponding 
to the present state of the art, the gasification reactor is provided with 
more than two burners, which advantageously are arranged in pairs. When 
the number of the burners is greater for example than 6, the arrangement 
of the burners in pairs can also be dispensed with. They can be 
distributed over the whole periphery of the gasification reactor in one 
plane. In all above mentioned cases, the fuel supply of the burners is 
performed from single supply container, which leads to considerable saving 
in apparatus and operational costs. It should be taken into consideration 
that each supply container can be associated with the required 
transporting or sluice device for bringing the fuel coming from a 
preparation installation to a required operational pressure and 
transferring the same into the supply container. 
In the inventive arrangement the conduits for the fuel supply to the 
burners are connected with a distributor which is supplied with fuel from 
the supply container. This distributor is located as close as possible 
under the outlet of the supply container and connected with the latter by 
a rigid transporting conduit. An addition of a transporting gas in this 
conduit is dispensed with. Four conduits for the fuel supply to the 
burners normally extend from the distributor. However, if the number of 
the burners in the gasification reactor is greater, two or more 
distributors can be used in correspondence with the greater number of 
burners. The second and each further distributors are arranged in a 
conduit for the fuel supply from the first distributor to the burners. It 
should be understood that these additional distributors can also have 
conduits for the fuel supply to the burners associated with them. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An arrangement for gasification of fuels includes a supply container 1 
which shown in FIG. 1 and used for accommodating the fuel to be gasified. 
The supply container 1 is under pressure so as to provide for a pneumatic 
transportation of the fuel through respective conduits to burners 3, 4, 5, 
6 in a gasification reactor 2. For this purpose the fuel is withdrawn from 
the supply container 1 through a supply conduit 7 and supplied to a 
distributor 8. The distributor 8 is arranged relatively close underneath a 
funnel-shaped outlet of the supply container 1. As can be seen from the 
drawings both supply container 1 and the distributor 8 can be located at a 
certain distance from the gasification reactor 2. 
Conduits 9, 10, 11 and 12 extend from the distributor 8 for supplying the 
fuel to the burners 3, 4, 5 and 6. As can be seen from the schematic 
showing in FIG. 1, the conduits have different lengths and directions. The 
different pressure losses in the conduit 9, 10, 11 and 12, resulting from 
their different lengths and directions, are compensated in accordance with 
the present invention by providing of throttles 13. The throttles operate 
so that at the point of entrance of the fuel in the burners 3, 4, 5 and 6, 
the pressure loss between the distributor 8 and the respective burner is 
equal in all cases. In other words, in the conduit which because of its 
length and direction has a smallest pressure loss, the operation of the 
throttle 13 must be strongest. Vice versa, in the conduit with the highest 
pressure loss no throttle 13 at all can be provided. In the embodiment 
shown in the drawings, such a conduit is the conduit 10. The details of 
the construction of the throttles 13 are explained hereinbelow. 
Changes in the output of the gasification reactor 2 can be achieved by 
respective nominal value changes of a differential pressure regulator 20. 
The differential pressure regulator 20 can regulate the pressure 
difference between the supply container 1 and the gasification reactor 2. 
Alternatingly, the throttles 13 can be replaced with suitable regulating 
valves of a conventional construction which will maintain the fuel stream 
2 through each burner identical or different. In this case the 
differential pressure between supply container 1 and the gasification 
reactor 2 can be maintained constant. 
FIG. 1 shows only those parts of the arrangement which are necessary for 
illustrating the present invention. The specific details of the 
construction of such parts, such as for example, the supply container 1, 
the gasification reactor 2, the distributor 8, and the burners 3, 4, 5 and 
6 are not provided, since they do not constitute the subject matter of the 
present invention. It should be emphasized that these parts can be formed 
as conventional parts with constructions suitable for this purpose. It is 
to be understood that the supply container 1 must be provided with 
respective devices for subsequent feeding of the fuel and for maintaining 
the constant pressure, which are not shown in the drawings. They can be 
formed as known aggregates required for this purpose, such as for example, 
pressure cup conveyor or sluice bin. 
The details of the construction of the throttles 13 are shown in FIG. 2. 
This Figure shows a cross-section of the throttle. The throttle includes a 
cylindrical casing 14 with an outer diameter substantially corresponding 
to the flange diameter of the tubular conduit in which the throttle is 
inserted. Since the throttle is flanged in this tubular conduit, it is 
advantageous when the cylindrical casing 14 is composed of the same 
metallic material of which the tubular conduit is composed of. The 
cylindrical casing 14 has front and rear ends with inner diameter d.sub.1 
which corresponds to the inner diameter of the connected tubular conduit. 
A coating 15 is provided inside the cylindrical casing 14 and composed of 
a wear-resistant material such as for example ceramics. In some cases the 
coating can be assembled of several parts. The coating 15 has a shape 
which is designed so that it can receive a displacement body 16. 
The displacement body 16 is composed of a wear-resistant material and 
connected inside the coating 15 by means of a web 17. A ring-shaped gap 18 
is formed between the coating 15 and the displacement body 16. It 
corresponds to the height of the web 17. As can be seen from the drawings, 
the displacement body 16 has a cylindrical part in its center and two 
parts located at opposite sides of the cylindrical part and conically 
reducing toward the ends of the body. 
The coating 15 is sealed inside the cylindrical casing 14 by sealing rings 
19. The coating 15 is pressed into the casing 14 by a projection 21 on the 
flange of the tubular conduits to be connected. The pressure loss in the 
throttle is adjusted in accordance with the width and length of the 
ring-shaped gap 18, as well the fuel/supply gas speed in the annular 
cross-section of the gap 18. The gap 18 is greater than the tubular 
conduit which is guided in it with a diameter d.sub.1. 
The computation of a throttle which is suitable in condition of the 
so-called flow transportation is possible from experimentally obtained 
data with an accuracy of .+-.5%. The insertion of the throttle has, in 
addition to the desired pressure loss, also the advantage in that the 
coarse particles in the fuel which lead to clogging, such as for example 
fibers, are retained and cannot be supplied to the burner. Otherwise, it 
would be difficult to remove them from the burner. It is to be understood 
that the design of the throttles must be such that their action is not too 
high and does not lead to disturbances in the fuel supply to the burners 
because of clogging of the conduits. 
It should be mentioned that in addition to the distributor 8 shown in the 
drawings, also two or more distributors can be provided in the 
gasification arrangement in accordance with the present invention. In this 
case the second and each further distributor is arranged in a conduit for 
the fuel supply from the first distributor 8 to the burners 3, 4, 5 and 6. 
From these subsequent distributors again further conduits for the fuel 
supply to further burners are extended. 
As can be seen from the drawings, the distributor 8 which is arranged 
underneath the supply container 1 is connected with the latter by a short 
supply conduit 7. This supply conduit 7 has no connection for an 
additional supply of a supplying or transporting gas. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
constructions differing from the types described above. 
While the invention has been illustrated and described as embodied in an 
arrangement for gasification of fuels, it is not intended to be limited to 
the details shown, since various modifications and structural changes may 
be made without departing in any way from the spirit of the present 
invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.