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Патент USA US3098479

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July 23, 1963
R. H. P. ROW
Filed Dec. 11, 1961
United States Patent 0 ” "ice
Ronald Henry Paddon Row, Bexley, Kent, England,
assignor to Foster Wheeler Corporation, New York,
N.Y., a corporation of New York
Filed Dec. 11, 1961, Ser. No. 158,404
1 (Ilaim. (Cl. 122-478)
Patented July 23, 1963
fan 34 arranged to take cooled combustion gases ‘from the
space 36v ‘between the economiser 19 and the ?ue.
When the fan 34 is put into operation, cooled gases are
delivered as shown by the broken line arrows through the
nozzles 32 with the result that the hot gases from the
furnace are diverted towards the baliie wall 26. The ex
tent to which they are so diverted depends on the orienta
tion of the nozzles and the rate at Which the cooled gases
emerge from them. By varying one or the other of these
This invention relates to water tube boilers having super
heaters heated by convection, and means to vary the 10 factors, the heat put into the steam in the superheater can
be varied. It will be ‘appreciated that a considerable
amount of heat added in the superheater.
variation of the ?nal steam temperature can thus be ef
The recirculation of cooled gases for attemperation of
fected as diversion of the hot gases away from the super
the hot gases by means of which the superheater is heated
heater is accompanied by subjection of a part of the
so as to control the temperature at the outlet from the
superheater is not at all uncommon. In accordance with 15 superheater to- the action of the cooled gases.
The fan can be controlled manually or automatically
the invention, however, while cooled gases are recirculated
by, for example, a controller which responds to changes
for control of the superheat temperature, they are used
in the steam temperature at the outlet of the superheater.
not for attemperation of the hot gases but for diverting
Alternatively, or in addition, provision can be made for
a variable proportion ‘of the inflowing hot gases ‘from and
shielding a variable portion of the superheater against the 20 cutting in and out one or more of the nozzles or for
varying their orientation. This however, is not the pre
effect of the hot gases.
ferred method of operation as it involves the provision of
This will generally involve housing the superheater in
mechanical parts in a hot area of the installation.
a compartment or cavity which is substantially wider than
What is claimed is:
the superheater as measured across the general direction
A water tube vapor generator comprising an elongated
of flow of the hot gases so that there is therein a space 25
bank of superheater tubes; means housing said bank and
unoccupied by the superheat-er into which the hot gases
de?ning an elongated gas passage which extends longi
can be forced by the cooled gases so that the hot gases
of said bank, said ‘bank of superheater tubes
pass onward out of contact with at least a part of the
and housing means being in a convection zone of said
superheater. The recirculated cooled gases can be made
to enter the superheater chamber for this purpose through 30 vapor generator, gas inlet and outlet means adjacent the
ends of said passage such that the ?ow of hot gas is ap
one or more nozzles ‘fed by a fan. The variation of the
proximately in the direction of the length of the passage
superheat temperature can be eifected by varying the rate
and along the length of said bank of said superheater
of discharge of the fan, or by cutting nozzles in and out
tubes, said passage being substantially wider than the
at appropriate times, or by altering the direction of dis
35 bank as measured across the general direction of flow of
charge of the cooled gases from the nozzles.
the gas and said bank being disposed along one side of
An example of a boiler in accordance with the inven
tion will now be described with reference to the accom
the passage so as to provide on the opposite side a space
approximately coextensive with the bank which is unoccu
pied; said gas inlet means, passage and bank however
vation of the boiler.
The boiler shown in the drawing is a D-type boiler of 40 being arranged such that the flow of hot gas normally is
through the superheater; means for withdrawing cool gas
a well-known type having an upper steam and water drum
from an ‘area of said generator downstream of said space;
10 ‘and a lower 'Wa-ter drum 12 connected by banks of
and adjustable means disposed in said passage along a side
steam generating tubes 14. It is ?red by burners 16 in a
of said bank removed from said space adapted to blow
furnace 18, the combustion gases following the path in
dicated by the full-line arrows through the steam generat 45 said cool gases in a substantially transverse direction
across said bank in a manner to divert a variable propor—
ing ‘banks ‘14 and an economiser 19‘ to an outlet 20 leading
tion of the stream of in?owing hot gases into said space.
to a ?ue.
On the furnace side of the steam generating bank 14,
References Cited in the ?le of this patent
there is a superheater 22 taking steam from the drum 10.
The superheater is arranged in a compartment or cavity
panying drawing which is a diagrammatic sectional ele
bounded by baffle walls 24 and 26 so that there is an
ample unoccupied space 28 on the furnace side of the
Amnacost ____________ __ Nov. 30*, 1954
Seidl _________________ __ July 9, 1957
Zoller _______________ _._ Ian. 26, 1960
Great Britain __________ __ June 2, 1932
Sweden ______________ __ Jan. 19‘, 1954
Between the superheater 22 and the ba?ie wall 24, there 55
are two pipes 30' extending across the furnace and pro
vided with nozzles 32. positioned at intervals across the
furnace. The nozzles are connected to the outlet of a
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