Apparatus for the conveyance of dust-like or dust containing solids into a pressurized system by means of a pressurized lock chamber

Dust-like or dust containing solids are passed into a pressurized system via a lock chamber apparatus wherein a porous filter is provided separating the lock chamber into an upper space and into a lower space. Normally a pressurized gas is passed into the lower space and it is discharged from the upper space during the pressure release phase after passing through the filter. When a predetermined differential pressure is exceeded between the upper and the lower space of the lock chamber because of a clogging up of the filter the filter is cleansed by passing the pressure gas partially or totally into the upper space of the lock chamber so that it passes through that filter in the direction reverse to that during the pressure release phase.

BACKGROUND OF THE INVENTION 
The invention relates to a lock chamber apparatus for conveying a dust-like 
or dust containing material into a pressurized system such as it is used 
during gasification of coal at elevated pressures. 
The conveyance of solid materials into a system of higher pressure is 
frequently effected by means of lock chambers. The lock chambers are 
filled at atmospheric pressure with the solid material and are then filled 
with a pressurized gaseous medium to reach a pressure level equal to that 
of the subsequent pressure system such as a coal gasifier. After 
completion of that phase the lock chamber pressure is released. Since, 
however, it is unavoidable that residual dust remains in the lock chamber 
the pressure-released gas is being contaminated and therefore a separate 
dust cleaning of the released gas is necessary in order to avoid pollution 
of the atmosphere by dust emissions and to avoid also technological 
disturbances. 
It is therefore an object of the invention to provide for an apparatus 
which dispenses with the separate dust removal device and to provide for 
otherwise carried out dust removal from the released pressure gas. Thus, 
the cost of the apparatus is reduced and the danger of technological 
malfunction is lowered and the loss in material is also decreased. 
SUMMARY OF THE INVENTION 
This is accomplished by an apparatus comprising 
a lock chamber; 
a filter partitioning said chamber into an upper and a lower space; 
an inlet and outlet from said lower space for said solid material; 
an inlet duct for introducing a pressurized gas into said lower space to 
raise the atmospheric pressure in said lock chamber to the pressure in the 
pressure system into which the material is passed; 
a flow control valve and a shut-off valve disposed in spaced relationship 
in said inlet duct for said pressure gas; 
a discharge duct in said upper space for the pressure gas when the pressure 
of the same is released after passing the gas through said filter where it 
is freed of entrained dust; 
a branch duct passing from a place intermediate said flow control valve and 
said shut-off valve and leading into said upper space; 
a shut-off valve, each, in said branch duct and in said discharge duct; and 
gauge means for measuring the differential between the pressure in said 
lower space and the pressure in said upper space, 
whereby upon a predetermined pressure differential indicated by said gauge 
means and due to the clogging up of said filter, pressurized gas may be 
blocked from entering said lower space and upon closing of said shut-off 
valve in the discharge duct and opening of the shut-off valve in the 
branch duct may be passed through said branch duct into the upper space of 
the lock chamber and through said filter into the lower space resulting in 
a backwash action on said filter. During the release of pressure in the 
lock chamber and while the pressure is lowered in the lock chamber to the 
pressure of the environment the mean pressure is still considerably above 
atmospheric pressure during the operation. Therefore, considerably smaller 
filter surfaces are necessary because of the lowered volume flow. 
Nevertheless, a substantial part of the dust eliminated by the filter 
falls back into the lower space of the lock chamber and a clogging up of 
the filter by fine dust could normally be completely prevented. This is 
however accomplished by the above invention where the pressure gas serves 
to clean the filter during the pressure cycle from any dust residues. 
In an embodiment of the invention the differential pressure meter may be 
combined with a control device which automatically opens the shut-off 
valve in the branch duct when a predetermined pressure difference is 
exceeded and at the same time may either open or close the shut-off valve 
in the inlet duct and may either open or close the discharge duct valve. 
The valves may thereafter be operated independently from the further 
development of the pressure difference through a predetermined time phase 
which should at least be equal to the time of a complete cycle. 
The advantage of the device of the invention is that no special implements 
or apparatus parts are necessary to remove entrained dust from the gas and 
the environment into which the pressure release gas is discharged is thus 
protected and the dust actually remains within the pressure system for 
further use. 
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 drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the drawing it will be understood that the dust-like or 
dust containing solid material is introduced into the lock chamber through 
the inlet 4 and after being pressurized therein is discharged through the 
outlet 5. The pressure gas is obtained from a duct 8 and passes through a 
flow control valve 13 and a shut-off valve 11 before passing into the lock 
chamber. A porous filter 3 is provided in the lock chamber which 
partitions the chamber into an upper space 6 and a lower space 7. As will 
be seen from the drawing the introduced solid material passes directly 
into the lower space. Likewise the pressure gas is introduced into the 
lower space preferably at the bottom portion thereof. 
In the upper space there is provided a gas release duct 9 which is 
controlled by a pressure release valve 14. During the pressure release 
cycle this valve 14 is opened while the valve 11 is closed. The pressure 
gas thus is released through the duct 9 to the atmosphere. During this 
step as appears from the drawing, the released gas must pass in upward 
direction through the filter 3. 
If the filter becomes clogged up there will be a pressure difference 
between the upper space 6 and the lower space 7. 
A branch duct 10 is provided as appears from the drawing between the flow 
control valve 13 and the shut-off valve 11. This branch duct leads into 
the duct 9 used in the pressure release cycle but merges into the duct 
below the pressure release valve 14. During the pressurizing of the lock 
chamber the pressure release valve 14 is closed while it is opened during 
the pressure release step. 
Gauge means 2 are provided to indicate the pressure differential between 
the upper space and the lower space of the lock chamber. If a certain 
predetermined limit value is exceeded a control device 15 is actuated 
which closes the shut-off valve in the inlet duct for the pressure gas and 
also closes the disharge valve 14. and opens the shut-off valve 12 in the 
branch duct 10. The pressure gas then passes through the duct 10 into the 
lock chamber via the discharge duct 9 since during this pressurizing step 
the pressure release valve 14 is closed. Alternatively the shut-off valves 
12 and 11 may also both remain open during the cleaning step. In that case 
only part of the pressure gas would pass through the duct 10, while 
another part would still pass in the normal way directly into the lower 
space of the lock chamber. Thus, all or part of the pressure gas may be 
passed into the upper space and effect the cleaning of the filter. 
Since the pressure differential is subject to variations during the 
pressure release step it is preferred that the valves 11, 12 and 14 are 
locked in their position by means of the control device 15 for a 
predetermined time period. This time period should at least correspond to 
the time of a complete lock chamber cycle in order to assure a sufficient 
cleaning of the filter. 
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.