[0001] This invention relates to a two-fluid nozzle for atomizing a liquid-solid slurry.
[0002] Synthesis gas produced by the partial oxidation of a carbonaceous material, e.g.,
coal, can have its heating value upgraded by feeding the gas to a vertical upflow
reactor for further reaction with an atomized carbonaceous slurry. The most significant
reactions to occur are between the fixed carbon provided by the carbonaceous slurry
and the CO₂ and water vapor content of the synthesis gas. These reactions yield CO
and H₂ which add to the heating value of the synthesis gas. The reactions are endothermic
and avail themselves of the heat contained in the synthesis gas feed which is at a
temperature in the range of from 1090°C to 1650°C and typically 1370°C.
[0003] The synthesis gas is usually obtained as the direct outflow from an entrained flow
gasifier and fed to a vertical flow reactor. Vertical flow reactors can be either
of the upflow or downflow type. Most commonly, the carbonaceous slurry is comprised
of water and particulate coal and generally contains approximately 50 weight percent
water. The carbonaceous slurry is fed to the vertical flow reactor in an atomized
state and is preferably directed into the synthesis gas so as to effect a uniform
dispersion of the carbonaceous slurry and the synthesis gas.
[0004] The nozzle of this invention is particularly suitable for use in atomizing a water-coal
slurry fed to a vertical flow reactor. Generally speaking, the coal is provided to
the slurry in a finely ground state so that substantially all of it passes through
an ASTM E 11-70C Sieve Designation Standard 1.40mm (U.S. Series No. 14) and at least
80 percent passes through an ASTM E 11-70C Sieve Designation Standard 425µm (U.S.
Series No. 40). The atomizing gas fed to the nozzle is preferably steam; however,
other gases such as, for example, nitrogen and synthesis gas may be utilized.
[0005] The two-fluid mixing nozzle of this invention comprises an elongate central conduit
for the flow of the liquid-solid slurry through the nozzle. The liquid-solid slurry
is introduced into or adjacent the distal end of the central conduit and is discharged
from its discharge, i.e., proximate, end. For ease in construction, the central conduit
can be provided by the interior wall of an elongate pipe. Surrounding at least a portion
of the length of the central conduit is an elongate annular conduit. The annular conduit
is used for the cocurrent flow of the atomizing gas through the nozzle. The gas is
introduced into or adjacent the distal end of the annular conduit and is communicated
from its discharge, i.e., proximate, end of the annular conduit to a plurality of
discharge conduits, hereinafter described. The annular conduit is coaxial with the
longitudinal axis of the central conduit. When the central conduit is formed by a
tube, the annular conduit is conveniently defined by the outside wall of the tube
and inside wall of a larger diameter tube which is coaxial with the first.
[0006] In gas communication with the annular conduit are the hereinbefore-mentioned plurality
of discharge conduits (ports). These discharge conduits each discharge the gas communicated
to them at an angle "a" within the range of from 10° to 80° with respect to an outward
extension of the longitudinal axis of the central conduit. The discharge conduits
are also peripherally located with respect to the discharge end of the central conduit.
By so angling and locating the discharge ports, the gas passing through them will
intersect and impact, in a uniform manner, the liquid-solid slurry stream discharging
from the central conduit. This intersecting and impacting results in disintegration
of the slurry stream to effect its atomization. It has been found that by having the
gas discharged from the discharge conduits at the hereinbefore described angles, high
atomization of the slurry is achieved. When the nozzle of this invention is to be
utilized for atomizing, say, a water-coal slurry feed, it is preferred that the angle
"a" at which each discharge conduit directs the gas communicated to it be within the
range of from 55° to 65° with respect to the outward extension of the longitudinal
axis of the central conduit. The selection of any particular angle "a" for other types
of feeds will be dependent upon the velocities of the liquid-solid slurry and the
gas as they leave their respective conduits, the physical characteristics of the liquid-solid
slurry and the degree of atomization sought. Considering the interdependence between
these three factors, angle selection is by empirical methods.
[0007] It is preferred that the discharged conduits be substantially equidistantly spaced
from one another and substantially equidistantly displaced from the longitudinal axis
of the central conduit. By so locating the discharged conduits, uniformity in distribution
of the disintegrating force on the discharged liquid-solid slurry is achieved, thus
resulting in high fidelity atomization.
[0008] If desired, the discharge conduits can be dimensioned to have a total cross-sectional
area for flow which is less than the cross-sectional area for flow provided by the
annular conduit. By providing this disparity in the cross-sectional areas for flow,
the velocity of the gas leaving the discharge conduits is increased over its velocity
in the annular conduit, which increase can be beneficial in effecting better atomization
than would be possible if the gas was discharged at its velocity in the annular conduit.
[0009] These and other features of this invention will be more fully understood from the
following description and drawings in which identical numerals refer to identical
parts and in which:
Figure 1 is a cross-sectional view of an embodiment of this invention taken along
its longitudinal axis; and
Figure 2 is a front view of the mixing nozzle shown in Figure 1.
[0010] Referring now to Figures 1 and 2, there can be seen a two-fluid nozzle of this invention,
generally designated by the numeral 10. Nozzle 10 includes an elongate outer tube
which has an inside wall 14. Coaxially located within outer tube 12 is central tube
16. Central tube 16 is maintained in this coaxial position by means of two sets of
spacers. One set of spacers comprises spacers 30, 31 and a third spacer, not shown,
while the other set of spacers comprises spacers 32, 33 and a third spacer, not shown.
The spacers are preferably of a narrow width and, in each set, are located 120° from
one another.
[0011] Nozzle 10 provides an annular conduit 35 for gaseous flow through the nozzle by means
of inside wall 14 of outside tube 12 and outside wall 18 of central tube 16. Also
provided by nozzle 10 is central conduit 36 which is defined by inside wall 20 of
central tube 16.
[0012] The liquid-solid slurry is fed into the distal end or portion 19 of central pipe
16 and is discharged therefrom at its discharge end 21. The gas, which will be utilized
to atomize the liquid-solid slurry, is introduced via feed conduit 13 to annular conduit
35 at the distal end or portion 15 of outer tube 12 and is discharged through a plurality
of discharge conduits 22, 23, 24 and 25 located at the discharge end 17 of annular
conduit 35. The number of discharge conduits can vary over a wide range, say, from
3 to 500 conduits. Generally, 3 to 20 conduits are preferred. As can be seen in Figure
2, the discharge conduit open onto nozzle tip face 29 and are equidistantly spaced
from one another and from the longitudinal axis of central tube 16. Nozzle tip face
29 is substantially coplanar with the discharge end 21 of central tube 16. By substantially
coplanar, it is meant that nozzle tip face 29 and discharge end 21 are within 0 to
2.54 cm of being in a true coplanar relationship.
[0013] The discharge conduits each have two portions, an intermediate portion and an angled
portion. The angled portion extends from the intermediate portion at an angle "a"
within the range of from 10° to 80° with respect to an outward extension of the longitudinal
axis of the central tube 16. When atomizing a water-coal slurry feed, angle "a" is
preferably from 55° to 65°. For discharge conduits 22 and 24 shown in Figure 1, the
intermediate portions are designated by the numerals 22
a and 24
a, respectively, and the angled portions are designated by the numerals 22
b and 24
b, respectively. Discharge conduits 23 and 25 are similarly configured. The total cross-sectional
area for flow of the three discharge conduits measured at their intermediate portions
is less than that for annular conduit 35. Further, the cross-sectional area for flow
of each of the angled portions of the discharge conduits is less than that provided
by each intermediate portion associated with its angled portion partner. By having
this decrease in the total cross-sectional area for flow from annular conduit 35
to the angled portions of the discharge conduits, the velocity of the gas being discharged
from nozzle 10 is much higher than the velocity of the gas as it passes through annular
conduit 35. This increase in gas velocity results in better atomization of the slurry
by shearing and disintegration of the liquid-solid slurry being discharged from central
conduit 36.
[0014] Sizing of the various conduits and the selection of the angles for the discharge
conduits are dependent upon the gas reactant feed rate to the reactor, the liquid-solid
slurry composition and feed rate, the atomizing gas feed rate and its velocity of
discharge from the discharge conduits and the degree of atomization sought. As mentioned
previously, such determination is made empirically. For example, after empirical study,
it was found that nozzle 10 could be specified as follows:
outside tube 12 3/4" (19 mm) diameter 310 SS SCH. 40
central tube 16 1/8" (3.175 mm) diameter 310 SS SCH. 40
intermediate portions of discharge conduits 22, 23, 24 and 25 3/16" (4.76 mm) diameter
angled portions of discharge conduits 22, 23, 24 and 25 3/32" (2.38 mm) diameter at
an angle of 70° with longitudinal axis of pipe 16.
[0015] Such a nozzle provides a good atomized water-coal feed to a vertical flow reactor
which has fed, to its bottom, synthesis gas flowing at the rate of 380 actual cubic
ft/hour (0.003 m³/s). The water-coal slurry is fed to the nozzle at a rate of 42 gallons/hour
(0.0441 l/s) while the atomizing gas, i.e., steam, is fed to the nozzle at a rate
of 50 lbs/hour (22.68 kg/hr).
[0016] While certain representative embodiments and details have been shown for the purpose
of illustrating the present invention, it will be apparent to those skilled in the
art that various changes and modifications can be made without departing from the
spirit and scope of the invention.
1. A two-fluid mixing nozzle which comprises: (a) an elongate central conduit (18)
for the flow of a liquid-solid slurry through said nozzle, the conduit having a distal
end for introduction of the slurry and a discharge end for the discharge of the slurry;
(b) an elongate annular conduit (12) for the flow concurrently with said flow of the
slurry, of a gas through the nozzle, the annular conduit having a distal end (15)
for the introduction of the gas and a discharge end provided with a plurality of discharge
conduits (22b), wherein the elongate annular conduit is substantially coaxial with
the longitudinal axis of the central conduit and circumscribes at least a portion
of the length of the central conduit; and wherein the discharge conduits (22b) are
peripherally located adjacent the discharge end of said central conduit, and wherein
each of the said discharge conduits is arranged to discharge the gas communicated
to it at an angle of from 10° to 80° with respect to the outward extension of said
longitudinal axis whereby the discharged liquid-solid slurry is impacted by the discharged
gas to effect the atomization of said liquid-solid slurry.
2. A nozzle as claimed in Claim 1 wherein the discharge conduits (22b) each have an
angled portion from which said gas is discharged and an intermediate portion which
is between the annular conduit and the said angled portion, the angled portion extending
from the intermediate portion at an angle "a" within the range of from 10° to 80°
with respect to an outward extension of the longitudinal axis of the central conduit.
3. A nozzle as claimed in Claim 2 wherein the cross-sectional area for flow of each
of the said angled portion is less than the cross-sectional area for flow of the said
intermediate portion associated with the angled portion.
4. A nozzle as claimed in Claim 2 or Claim 3 wherein the total cross-sectional area
for flow for said intermediate portion is less than the cross-sectional area for flow
of said annular conduit.
5. A nozzle as claimed in any one of the preceding claims wherein the discharge conduits
open onto a nozzle tip face and are substantially equidistantly spaced from one another
and substantially equidistantly displaced from the longitudinal axis of the central
conduit.
6. A nozzle as claimed in any one of the preceding claims wherein the discharge conduits
open onto a nozzle face, the nozzle face being substantially coplanar with the discharge
end of the elongate central conduit.
7. A nozzle as claimed in any one of the preceding claims wherein there are from 3
to 500 discharge conduits.
8. A nozzle as claimed in any one of the preceding claims wherein said angle is from
55° to 65°.
9. A vertical flow reactor for carbonaceous slurries, comprising a nozzle as claimed
in any one of the preceding claims.
10. A method of atomizing a carbonaceous slurry, which method comprises passing the
slurry through the first conduit of a nozzle as claimed in any one of Claims 1 to
8, and passing a gas through the second conduit to effect atomisation of the slurry.