U.S. patent number 3,592,562 [Application Number 04/875,732] was granted by the patent office on 1971-07-13 for takeoff for hot dusty gases.
Invention is credited to Heniz Spliethoff.
United States Patent |
3,592,562 |
Spliethoff |
July 13, 1971 |
TAKEOFF FOR HOT DUSTY GASES
Abstract
A takeoff using injector action to aspirate dirty furnace gas
from a sample zone and force it to an analyzer. Part of the water
used for injector action is used to scavenge and rinse the walls of
the gas takeoff passageway, with centrifugal force of water
rotation holding the major cross-sectional area of the passageway
open. Washing stream is biased to move counter to gas aspiration
and leaves the device as a conical water curtain opening toward the
furnace.
Inventors: |
Spliethoff; Heniz (Auf den
Hanbuchen, DT) |
Family
ID: |
5713322 |
Appl.
No.: |
04/875,732 |
Filed: |
November 12, 1969 |
Foreign Application Priority Data
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Nov 14, 1968 [DT] |
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P 18 08 886.3 |
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Current U.S.
Class: |
73/863.12;
261/78.2; 417/197; 73/864.73; 417/160 |
Current CPC
Class: |
G01N
1/2258 (20130101); G01N 2001/242 (20130101); G01N
1/24 (20130101) |
Current International
Class: |
G01N
1/22 (20060101); G01N 1/24 (20060101); F04f
005/44 (); G01n 001/24 () |
Field of
Search: |
;417/160,171,194,197
;73/421.5A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Gluck; R. E.
Claims
The invention I claim is in the following:
1. In a device for drawing very hot dust-laden gas from furnaces
for analysis of the gas, inner and outer coaxial tubes having an
annular space therebetween, closure means for partially closing the
tubes at adjacent ends thereof as furnace-side ends of the device,
the closure means being provided with a short cylindrical gas
passageway for entrance of the gas from the exterior of the closure
means into the inner tube, walled means within the outer tube
forming a jet passage communicating between the interior of the
inner tube and the annular space for receiving water flowing in the
latter toward the furnace-side end and causing the water to issue
as an injector jet into the inner tube and aspirate the gas through
the gas passageway into the inner tube and force it through the
latter, said closure means being provided with a side bore
communicating between the annular space and the gas passageway for
injecting water into the latter with a rifling action to rinse the
walls of the gas passageway and leave the latter as a water curtain
having a conical mantle opening toward the furnace.
2. In a device as claimed in claim 1, said closure means
obstructing the flow of part of the water flowing toward the
furnace-side end to give the jet reverse motion.
3. In a device as claimed in claim 1, said side bore joining the
cylindrical gas passageway essentially tangentially so that water
entering the passageway will tend to become rotated about the axis
of the passageway and become centrifugally forced against the walls
of the passageway and leave the more central zone open for said
entrance of the gas.
4. In a device as claimed in claim 3, the side bore being inclined
toward the furnace-side end at the interior of the gas passageway
so that water swirling at the walls thereof will be biased to move
counter to the direction of aspiration of the gas and leave the
closure means as said conical curtain.
5. In a device as claimed in claim 4, said closure means being a
plug closing the outer tube and provided with an inner extension of
reduced diameter projecting into the inner tube, the gas passageway
being an axial bore through the plug extension, the extension being
provided with a lateral cutaway forming a wall thereon which with
the inner wall of the inner tube constitute said walled means, and
said side bore being through the extension.
Description
DESCRIPTION OF THE PRIOR ART
Devices for the extraction or taking off of very hot dust-laden
flue or exhaust gas from furnaces are beset with extraordinarily
unfavorable operation. The high temperatures in combination with
condensable and corrosive flue gas components cause a very marked
strain and demand on the material used in the pickup part
projecting back into the furnace. By careful selection of materials
and use of cooling water, abrasion and corrosion are reduced to a
tolerable but generally unsatisfactory amount. Great difficulties
have been encountered in insuring the takeoff tube over long
periods of service against at least partial stoppage by small solid
particles from the flue gas, which particles, in combination with
condensable other components cause deposits and incrustations. It
is possible, of course, to keep the takeoff tube open by pushing an
iron rod through the tube, but this is most inconvenient and a
costly way of maintenance. Besides, dislodged particles can remain
in the takeoff tube and cause disturbances in the taking off of the
gas samples.
In order to extend the useful life of the takeoff device, it has
been the practice to apply wash water to the device. The wash water
is intended to reduce formation of encrustations inside the takeoff
tube and it also enables the picking up and washing away of solid
particles drawn in with the flue gas.
Such a flue gas takeoff for very hot and dust-laden gas is
described in German Pat. No. 953,926 wherein the takeoff tube has
nozzles or an annular space directly at the gas entrance opening,
the nozzles or space providing for the injection of scavenging
water in a second tube to flow in the direction of the gas stream.
The gas is aspirated by the injector action of the water stream and
led to gas analyzing instruments without further transport means,
the injector action giving sufficient movement to the gas. The
injected water rinses the inner wall of the forward part of the
takeoff tube and reduces the tendancy there toward clogging by
deposits of solid particles from the flue gas. But there is, of
course, the ever present danger that the solid particles will
become fixed on the foremost nozzle rim and cause a slow
incrustation of the inlet opening or, with the action of the water,
lead to erosion and consequently shorten the operative life of the
device.
Another takeoff using wash water is described in U.S. Pat. No.
2,550,933 which has a central water supply tube provided with a
bulge shortly ahead of the forward opening with several nozzles.
The water from the nozzles sprays toward the takeoff opening
counter to the direction of gas aspiration as well as perpendicular
to the walling of the takeoff tube. So much water is sprayed out
toward the furnace space, to reduce the obstruction of the takeoff
opening, that the active cross section for gas entrance through the
bulging of the water supply tube is markedly reduced. Not only
that, but the waterflow paths spread out unrestrictedly over the
entire entrance opening of the gas intake. The result is that there
is really no injector action by the waterflow for subsequent
transport of the gas and that a force pump is necessary to convey
the gas to an analyzer. The possibility of using self-acting
injector effects for aspiration and further conveyance of the gas
is not suggested. Such a device, however, is susceptible to the
danger that deposits may build up and tend to restrict the active
entrance space for the gas and result in a clogging up of the
takeoff tube.
The invention has for its object the production of a takeoff device
utilizing scavenging water operable for flue gas and the like
having a very high proportion of solid particles held in
suspension, and in which the defects of conventional devices are
not present, and so enable an especially long operable life.
BRIEF DESCRIPTION OF THE INVENTION
The takeoff device includes inner and outer coaxial tubes between
which water flows toward the furnace-side end of the two tubes
where the flow is reversed to flow outwardly inside the inner tube,
and so produces an injector action to aspirate sample flue gas into
the inner tube to carry the gas along to a gas-analyzing device.
The flue gas is aspirated through a short cylindrical takeoff
conduit passageway. The water is injected into the system of the
two tubes also in such a way that it acquires substantially rotary
momentum about the axis of, and in, the cylindrical passageway and
is also forced counter to the direction of gas aspiration so that
it leaves the takeoff device in the form of a conical water shield
opening toward the furnace space.
A particular form of the invention has a furnace-side end piece of
the takeoff device provided with a central bore therethrough as
well as through a projection thereon extending into the inner tube,
partially closing the latter. This projection is provided with a
water inlet bore for leading a part of the water flowing between
the two tubes into the passageway somewhat tangentially thereto and
counter to the direction of gas aspiration.
BRIEF DESCRIPTION OF DRAWING
FIG. 1 is a partial diametric longitudinal cross-sectional view of
the invention, and
FIG. 2 is a cross-sectional view of the invention, the section
being taken along the line A-B of FIG. 1, looking in the direction
of the arrows of said line.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The takeoff device is closed off at the furnace-side end (to the
left in the drawing) by means of a threaded plug 1. The
furnace-side end may be inserted through the walls of the furnace
or to a zone providing a representative gas sample. The plug is
provided with a central or axially directed bore 2 which forms the
gas pickup passageway. The plug is provided with a projection 3 of
reduced diameter projecting into an inner tube 4 so that an opening
or jet passage 5 remains free in the inner tube 4 of the device.
This opening is formed by the removal of a lateral portion of the
projection (FIG. 2) leaving a flat face 5' parallel with the bore
axis and away from the inner wall of the tube 4. Otherwise, the
projection has a tight fit in the inner tube, but spaced from the
main body of the plug as shown in FIG. 1.
The scavenging water, that also effects the cooling of the takeoff
device, flows from a supply (not shown) into an annular space 6
between an outer tube 7 on the body of the plug and the inner tube
4, to the furnace-side end of the device and thence through the
opening 5, being directed in the reverse direction in this annular
space 6 at the furnace-side end of tube 4 by striking the main body
of the plug 1 at the location of the opening 5 and issuing
therefrom as an injector jet. By means of injector action, the flue
gas is aspirated through the takeoff passageway 2 and sent through
the inner tube 4, owing to the water stream, on to a gas analysis
instrument (not shown). A separate gas conveying pump is not
needed.
The projection 3 of the plug 1 is provided with a small side bore 8
through which water arrives from the annular space between the
inner and outer tubes 4 and 7 and enters into the gas takeoff
passageway 2 so that it wets the inner walls of the passageway with
rifling or helical motion, counter to the direction of aspiration
of the gas, leaving the gas-entrance opening 9 at the furnace end
of the plug in the form of a conically mantled or shaped water
shield or curtain opening to the furnace space as indicated by the
spreading arrows. This helical sort of scavenging of the gas
passageway is effected by having bore 8 enter the passageway
somewhat inclined toward the furnace side as shown in FIG. 1 and
also more or less tangentially as shown in FIG. 2. Scavenging of
this nature not only has the advantage of preventing deposits from
forming in the passageway but also of not hindering the inflow of
gas, both of these advantages being due to the fact that the water
wets the wall only as a thin moving coating. The gas passageway is
therefore not throttled in spite of the wetting and the action of
the injectors is not impaired. Furthermore, the aspirated flue
gases are purified at least to some extent by passage through the
extending water cone and this is advantageous in protecting the
takeoff device as well as reducing the load on subsequent treating
means.
The conduction or transport of the gas from the takeoff to gas
analyzers is done in known manner after separation of the water in
a collecting vessel as well as, in extraordinary circumstances,
after purification by a filter. Owing to the intensive scavenging
and washing process, filters exhibit neither darkening nor fading
over long periods of operation. This shows that the large amount of
scavenging and transport water also remove such components from the
measuring gas as would disturb the measuring operation of analyzers
by deposits or corrosion.
By having the wash water inlet 8 tangential, the wash water rotates
in the bore so as to form only a relatively thin sheet of water on
the inner walls of the passageway 2. A slant of the inlet, about
30.degree. being satisfactory, relative to the passageway axis
insures that the water move to the water outlet 9 to form the water
cone. Increases in pressure on the water in the annular space 6,
producing higher flow velocities through the jet space 5 and
greater gas aspiration, also produce greater rotary and
longitudinal velocities in the passageway 2 so that increases in
the gas aspiration are accompanied by increases of centrifugal
force holding the wash water on the passageway walls to keep the
passageway effectively open and by more water to stabilize the
water curtain.
Preferably, water inlets 5 and 8 open into the space 6 remote from
each other so that waterflow at one does not adversely affect
pressure at the other.
The length of the gas passageway from side bore to the exterior
preferably should not be more than a few centimeters lest the
centrifugal action become reduced at the gas opening 9 and allow
the water to throttle it. Some swirling water will follow the gas
through the extension and so enable the whole passageway 2 to be
protected.
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