Gas cooling device for a gasifer

A device for cooling a stream of hot producer gas exiting from a gasification reactor operating at an increased pressure, includes a set of water spraying nozzles directed against the producer gas stream. Water feeding conduits connected to the nozzles pass through a sealing web provided between the pipe wall structure of the reactor and a separate pipe wall structure of a gas outlet connection piece provided above the discharge opening of the reactor. The geometric locations of respective nozzles are on a circle whose diameter is larger than that of the gas discharge opening and is smaller than the inner diameter of the pipe wall structure of the connection piece.

BACKGROUND OF THE INVENTION 
The present invention relates in general to a gasification reactor 
operating at an increased gas pressure and including a tubular first pipe 
wall structure having a circular gas discharging opening on its top, an 
outlet connection piece including a tubular second pipe wall structure 
concentrically surrounding the gas discharging opening and being sealingly 
connected to the first pipe wall structure, and two separating cooling 
circuits for supplying a cooling medium through respective pipe wall 
structures. In particular, this invention relates to a cooling device 
including water spraying nozzles directed against the hot stream of 
producer gas exiting from the reactor. 
Reactions taking place in a gasification reactor between the fuel, for 
example finely pulverized coal and the gasifying oxygen and steam produce 
final gasification temperatures between about 1300.degree. to 1600.degree. 
C. Depending on the softening behavior of fuel ashes at higher 
temperatures, it is required that the hot crude gas exiting from the 
interior of the reactor be cooled in a suitable manner below the softening 
point of ash particles entrained in the gas stream in order to prevent 
their caking and deposition during further processing. 
The cooling of the hot crude gas also called quenching, can be made by 
admixing thereto a fedback stream of cool producer gas or by steam or by a 
direct spray of water. In spraying water the cooling of the crude gas 
results from the removal of enthalpy needed for vaporization of water as 
well as from the heating of stream to the quenching end temperature of the 
gas. 
It is known to supply a cooling medium, particularly water into 
gasification installations operating substantial under normal pressure, 
through conduits opening into a gas outlet connection piece which is 
usually designed in the form of a double jacket arranged downstream of the 
gasification reactor. 
In gasification installations operating at an increased pressure this prior 
art arrangement of spraying nozzles is not feasible in practice inasmuch 
as the gas outlet connection piece as well as other parts of the 
installation for stability reasons are designed preferably as pipe wall 
structures. Such pipe wall structures, however, do not allow the feed 
through of the supply conduits for the cooling medium for the nozzles 
without causing disturbances on the inner side of the pipe wall that is 
attacked by the discharged hot gas. The points of penetration of the 
supply conduits into the pipe wall structure enhance the baking on of 
streaming ash particles as well as various erosion phenomena. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of this invention to avoid the disadvantages of 
prior art gas cooling devices of this kind. In particular it is an object 
of this invention to provide an improved supply of cooling medium into a 
stream of hot raw gas exiting from a gasification reactor operating at an 
increased pressure which is not possessed by the aforementioned 
disadvantages. 
In keeping with these objects and others which will become apparent 
hereafter, one feature of this invention resides in feeding the water 
supply conduits for respective water spraying nozzles in the interior of 
the gasification system, between two separate pipe wall structures of the 
gasification reactor and of the gas outlet connection piece, and the 
nozzles are arranged along a circular section whose diameter is larger 
than that of the gas outlet opening of the pipe wall structure of the 
reactor and is smaller than the inner diameter of the tubular pipe wall 
structure of the gas outlet connection whereby both pipe wall structures 
are supplied by a cooling medium from separate cooling circuits. 
Accordingly, in the arrangement according to this invention the water 
supply conduits for the water spraying nozzles penetrate into the inner 
spacee of the gasification system in the separation zone of the adjoining 
pipe wall structures of the gasification reactor and of the gas outlet 
connection piece and consequently the pipe wall structures themselves are 
out of contact with the water supply conduits and therefore no negative 
effects on the stream and no baking on or erosion on the inner sides of 
the pipe wall structures can occur. The arrangement of the water spraying 
nozzles on the beforementioned circular section has the advantage that the 
nozzles are located leeward the exiting gas stream and consequently are 
not subject to clogging by solid particles entrained in the gas stream. 
The orientation of the nozzles can be adjusted such that the spray is 
directed against the stream of crude gas, or perpendicularly thereto or on 
its streaming direction or in an intermediate position relative to the 
streaming direction. The number and size of the nozzles depends on 
specific requirements, that means on the intended cooling effect. 
In a further elaboration of this invention, apart from the water spraying 
nozzles arranged on a circular section, there are also arranged 
water-steam spraying nozzles directed against the inner side of the pipe 
wall structure of the connection to remove possible cakings on the inner 
wall of the gas outlet connection piece. In this embodiment, the water 
spraying nozzles and the water-stream spraying nozzles are preferably 
alternately arranged on the circular section. 
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 
In the figures, reference numeral 1 designates a tubular pipe wall 
structure of a gasification reactor 2 provided on its top with a gas 
discharge opening 3. Crude gas generaed in the reactor streams through the 
discharge opening 3 in the direction of arrow A and flows through a gas 
outlet connection piece 4 which surrounds the outlet opening. The gas 
outlet connection piece 4 is formed by a separate tubular pipe wall 
structure 5. As illustrated in the figures, both pipe wall structuress 1 
and 5 are mutually independent systems each connected to a separate 
cooling circuit. Both systems are accommodated within a common pressure 
jacket 6. According to this invention, water supply conduits 7 are 
directed into the interior of the gasification system through a sealing 
web 11 between the two pipe wall structures 1 and 5 and are terminated by 
the water spraying nozzles 8. Reference numerals 9 and 10 denote 
respectively water feed-in lines 9 and water collecting pipe 10 
communicating both with the lines 9 and with the water supply conduits 7. 
The sealing web 11 provides a gas tight closure between the separate pipe 
wall structures. 
The water spraying nozzles 8 are arranged along a circular section having a 
diameter D.sub.W which is greater than the diameter D.sub.G of the gas 
discharge opening 3 of the pipe wall structure 1 but is smaller than the 
inner diameter D.sub.A of the pipe wall structure of the gas outlet 
connection piece 4. Accordingly, the nozzles 8 are arranged leeward the 
stream of crude gas flowing in the direction of arrow A. Preferably, the 
nozzles are uniformly distributed on the circular section of the diameter 
D.sub.W whereby the number and the size of the nozzles as well as the 
angle alpha the water spray cone 12 are determined according to 
operational requirements. In the illustrated example of FIG. 1, the 
nozzles are directed obliquely toward the center axis of the gas stream A. 
As mentioned before, however, the orientation of the nozzles can be 
arbitrary depending on the desired effect. 
In FIG. 2, structural elements corresponding to FIG. 1 are designated by 
like reference numerals. In this embodiment, in addition to water spraying 
nozzles 8, there are also provided along the circular section of diameter 
D.sub.W steam spraying nozzles 13. Preferably, the nozzles 13 alternate 
with the nozzles 8. The supply of steam to the nozzles 13 is provided 
through steam feedin lines 14, a steam collection pipe 15 and steam supply 
conduits 16 which similarly as the water supply conduits 7 are fed through 
the sealing web 11 to open into the interior of the gasification system. 
The steam cone 17 emanating from each of the nozzles 13, as illustrated in 
FIG. 2, is directed against the inner side of the pipe wall structure 5 of 
the connection piece 4. The steam jet serves for an effective removal of 
deposits and possible bakings on the inner surface of the structure 5. The 
number, size, inclination and arrangement of the steam spraying nozzles is 
dependent on particular cleaning requirements.