Apparatus for relieving a lock chamber for ash from pressure

The lock container is connected to a reactor, which serves to gasify or to combust solid fuels. The lock container serves to remove ash from the reactor. A pressure of at least 2 bars prevails in the reactor. The lock container is pressurized and pressure-relieved in alternation. The pressure relief line communicates with a filter element, which is permeable to gas and substantially impermeable to solids and is disposed within the lock container. When the lock container is filled to the usual level during a pressure relief, at least one half of the filter element is surrounded by ash. The filter element may be tubular.

BACKGROUND OF THE INVENTION 
This invention relates to a lock container, which communicates with a 
reactor, which is operated under a pressure of at least 2 bars and serves 
to gasify or combust solid fuels, which container serves to remove ash 
from the reactor and is pressurized and is relieved from pressure via a 
pressure relief line. The term "ash" usually describes solid residues, 
which may also contain carbon. 
Such a lock container is known and has been described, e.g., in Published 
German Application No. 33 33 870 and in the corresponding U.S. Pat. No. 
4,608,059. When the lock container has received ash from the reactor and 
must subsequently be relieved from pressure before it is emptied, 
considerable amounts of fine ash will be entrained by the gas flowing to a 
pressure relief. If a filter is incorporated in the pressure relief line, 
that filter will soon be clogged by the solids and will frequently have to 
be backpurged or replaced. 
SUMMARY OF THE INVENTION 
It is an object of the invention to ensure that the gas flowing to effect a 
pressure relief can leave the lock container freely during the longest 
possible operating time and that the maintenance work required for the 
filter will be minimized. This is accomplished in accordance with the 
invention in that the pressure relief line communicates with a filter 
element, which is permeable to gas and substantially impermeable to solids 
and is disposed within the lock container and at least one half of which 
is surrounded by ash during a relief of pressure when the lock container 
is filled to the usual level. In that case that portion of the filter 
element which is surrounded by the bed of ash during a pressure relief 
cannot or can hardly be clogged by finely divided ash because even finely 
divided ash contained in the bed will not be moved or will hardly be moved 
by the flowing gas. That reduced movability of the fine-grained ash is 
ensured by the coarse-grained fraction of the ash. 
The filter element may be formed in various ways. The filter element is 
suitably tubular so that it may have a large surface and yet can be pulled 
out and inserted through a small opening in the lock container.

DETAILED DESCRIPTION OF THE INVENTION 
Solid fuels are gasified or combusted in a reactor 1 under a pressure of at 
least 2 bars. Only the lowermost portion of the reactor 1 is shown; that 
portion is succeeded by the lock container 2. A shut-off device 3 is 
provided between the reactor 1 and the container 2. When that shut-off 
device is open, it permits ash to flow from the reactor 1 into the 
container 2. The outlet of the lock container is also provided with a 
shut-off device 4. 
In the FIGURE the lock container is shown in the state assumed shortly 
before or during the pressure relief. For a pressure relief, the valve 6 
is opened so that gases can escape from the container through the filter 
element 7 and the pressure relief line 8. The valve 9 is closed. Because 
the filter element is entirely surrounded by the ash bed 10, the 
relatively coarse grains of ash prevent fine particles of ash from moving 
freely with the gas flowing to effect a pressure relief and from clogging 
the pores of the filter element 7. In order to produce that desirable 
result at least in part, the filter element 7 ius desirably so designed 
and arranged that at least one-half of its porous surface is surrounded by 
the ash bed. But the filter element is preferably disposed entirely or 
substantially in the ash bed. 
When the lock container 2 has been relieved to atmospheric pressure, the 
shut-off device 4 is opened so that the ash can flow off. For the sake of 
precaution the pressure relief line 8 is connected to a line 11 so that 
water vapor or backpurging gas can be introduced into the filter element 
through the line 11 and the open valve 9 and the pores of the filter 
element 7 can be purged from the inside to the outside. But this will only 
rarely be required. In order to further decrease the frequency of purging 
operations it is recommended to connect a plurality of filter elements to 
the pressure relief line. The filter elements consist, e.g., of silicon 
carbide or heat-resisting mineral fibrous materials, inorganic filters, 
ceramic fibers or composite materials.