Injection lance with variable swirl
A fuel injection lance for an ore-smelting furnace includes a central conduit, a first conduit and a second conduit. The first and second conduits are concentric with the central conduit. A central conduit is connected to a fuel mixture. The first and second conduits are in flow communication with a gas source. The first and second conduits have gas flowing at independently controllable gas flow rates relative to the other conduit. A swirl portion has a cylindrical body with a hollow interior cylinder, and vertical and helical channels formed within the body portion. Vertical channels traverse the body portion vertically to the outer surface adjacent to the bottom surface. Helical channels traverse the outer surface in a helical pattern. Vertical channels intersect with corresponding helical channels at a predetermined angle selected to provide a desired particle distribution of a fuel injected into the furnace.
1. A swirl portion of a fuel injection lance for an ore-smelting furnace, the swirl portion comprising:
a cylindrical body portion, a top surface, a bottom surface, an outer surface, and a hollow interior cylinder extending through the body portion along a center axis; and
a plurality of vertical channels and a plurality of helical channels formed within the body portion;
each of the vertical channels entering the body portion at the top surface at a radial distance intermediate the interior cylinder and the outer surface, and traversing the body portion vertically to the outer surface adjacent the bottom surface;
each of the helical channels traversing the outer surface between the top surface and the bottom surface in a helical pattern,
each of the vertical channels intersecting with a corresponding one of the helical channels adjacent the bottom surface at a predetermined angle selected to provide a desired particle distribution of a fuel injected into the furnace.
2. The swirl portion of claim 1 , wherein the vertical channels are configured to receive a gas flowing therethrough at a first flow rate from a gas supply, and the plurality of helical channels are configured to receive the gas flowing therethrough at a second flow rate from the gas supply, the first flow rate and the second flow rate being variable to adjust a swirl ratio for determining a fuel particle distribution at a discharge end of the injection lance.
3. The swirl portion of claim 2 , wherein the swirl ratio S is defined as a ratio of an angular momentum of the gas flow to a linear momentum of the gas flow, the swirl number S calculated according to:
S
=
∫
r
min
r
max
ρ
rw
v
->
·
ⅆ
A
->
R
_
∫
r
min
r
max
ρ
u
v
->
·
ⅆ
A
->
≡
Mass
weighted
average
of
(
r
×
w
)
R
_
×
Mass
weighted
average
of
(
u
)
.
4. The swirl portion of claim 1 , wherein each of the helical channels and vertical channels comprises a semi-circular cross section to impart a desired swirl pattern to a gas flow passing through the channels.
5. The swirl portion of claim 4 , wherein the diameter of the semi-circular cross section is about 0.13 inch.
6. The swirl portion of claim 1 , wherein a center line through each helical channel defines an angle α with respect to the center axis of body portion.
7. The swirl portion of claim 6 , wherein the angle α is 52.5° .
8. The swirl portion of claim 1 , wherein each helical channel revolves about 100° of the outer surface of the swirl portion.
9. The swirl portion of claim 8 , wherein the helical channels extend over about 1.5 inches of axial length.
10. The swirl portion of claim 6 , wherein angle a determines a fraction of angular momentum generated in a gas flow passing through helical channels.
11. The swirl portion of claim 1 , wherein the vertical channels have a semi-circular cross section.
12. The swirl portion of claim 1 , wherein the vertical channels enter the top surface adjacent to the interior cylinder
wherein each vertical channel further comprises:
a first vertical section at the top surface of swirl portion, a second vertical section disposed at the outer surface
the second vertical section adjacent to an end of a corresponding helical channel; and
a transition section interconnecting the first vertical section and the second vertical section in flow communication.
13. The swirl portion of claim 1 , wherein the helical channels comprise parameters modified based on a specific air flow and a fuel particle distribution requirements, the parameters including one or more of a channel size, a swirl exit angle and a length of the respective helical channel.
14. A fuel injection lance for an ore-smelting furnace, the fuel injection lance comprising:
at least three pipes arranged to define a central conduit, a first conduit and a second conduit, the first conduit and the second conduit concentrically arranged relative to an axis of the central conduit;
the central conduit connected to a fuel source comprising a solid particulate entrained in a fluid gas stream, and each of the first conduit and the second conduit in flow communication with a gas source;
the first and second conduit each having gas flowing therethrough respectively at independently controllable gas flow rates relative to the other conduit; and
a swirl portion comprising:
a cylindrical body portion, a top surface, a bottom surface and an outer surface, the central conduit extending through the body portion; and
a plurality of vertical channels and a plurality of helical channels formed within the body portion, the vertical channels in flow communication with the first conduit and the helical channels in flow communication with the second conduit;
each vertical channel of the plurality of vertical channels entering the body portion at the top surface at a radial distance intermediate the central conduit and the outer surface, and traversing the body portion vertically to the outer surface adjacent the bottom surface;
each of the helical channels traversing the outer surface between the top surface and the bottom surface in a helical pattern,
each of the vertical channels intersecting with a corresponding one of the helical channels adjacent the bottom surface at a predetermined angle, the predetermined angle selected to provide a predetermined particle distribution of a fuel injected into the furnace through a tuyere portion.
15. The fuel injection lance of claim 14 , wherein the vertical channels are configured to receive a gas flowing therethrough at a first flow rate from the gas source, and the helical channels are configured to receive the gas flowing therethrough at a second flow rate from the gas source, the first flow rate and the second flow rate being variable to adjust a swirl ratio for determining a fuel particle distribution at a discharge end of the injection lance.
16. The swirl portion of claim 15 , wherein the swirl ratio S is defined as a ratio of an angular momentum of the gas flow to a linear momentum of the gas flow, the swirl number S calculated according to:
S
=
∫
r
min
r
max
ρ
rw
v
->
·
ⅆ
A
->
R
_
∫
r
min
r
max
ρ
u
v
->
·
ⅆ
A
->
≡
Mass
weighted
average
of
(
r
×
w
)
R
_
×
Mass
weighted
average
of
(
u
)
.