Liquid removal device and liquid removal method
There is provided a liquid removal device that removes liquid attached to a surface of a steel sheet, the device including a slit nozzle that jets gas to the surface of the sheet, the slit nozzle being installed so as to jet gas from a downstream side toward an upstream side in a movement direction of the sheet that moves relatively to the slit nozzle and being configured in a manner that a jet angle θ, a back face inclination angle β, and a back face length L of a nozzle back face of the slit nozzle satisfy, β+θ≥ 60 ° and L≥ 20 mm, and a gap h between a jetting port of the slit nozzle and the sheet, a slit width d, and nozzle pressure P n of the slit nozzle satisfy the following relationship: P n ≥2.0×10 10 (h/d) 0.6 { 1/ ( 1 +exp(β+θ− 58 )+ 1 } −4 L −7 .
1. A liquid removal device that removes liquid attached to a surface of a steel sheet, the liquid removal device comprising:
a slit nozzle that jets gas from a jetting port to the surface of the steel sheet; and
a gap measurement device that measures a gap between the jetting port of the slit nozzle and the steel sheet,
wherein the slit nozzle is installed so as to jet gas from a downstream side toward an upstream side in a. movement direction of the steel sheet that moves relatively to the slit nozzle,
the movement direction of the steel sheet is a horizontal direction, and
the slit nozzle satisfies the following relational formulas:
P
n
≥
2.0
×
10
10
(
h
/
d
)
0.6
(
1
1
+
exp
(
β
+
θ
-
58
)
+
1
)
4
L
-
7
,
β
+
θ
≥
60
°
,
100
mm
≥
L
≥
20
mm
,
[
Math
.
1
]
where gas pressure inside the slit nozzle is defined as nozzle pressure P n [KPa],
an angle formed by a direction perpendicular to the surface of the steel sheet and a jet direction of the gas is defined as a jet angle θ [°],
an angled formed by the jet direction of the gas and a nozzle back face that is a face disposed from the jetting port of the slit nozzle toward the downstream side in the movement direction is defined as a back face inclination angle β[°],
a length of the nozzle back face in the movement direction is defined as L [mm],
the gap is defined as h [mm], and
a slit width of the slit nozzle is defined as d [mm].
2. The liquid removal device according to claim 1 , wherein the gap is adjusted to 20 mm or less on the basis of a measurement result of the gap measurement device.
3. The liquid removal device according to claim 2 , wherein the gap is adjusted by changing a position of the slit nozzle.
4. The liquid removal device according to claim 2 , wherein
the steel sheet is moved in the movement direction by a table roll that conveys the steel sheet, and
the gap is adjusted by changing a position of the table roll on which the steel sheet is placed.
5. The liquid removal device according to claim 2 , wherein
the gap measurement device measures the gap at each of measurement positions near both ends of the jetting port of the slit nozzle in a longitudinal direction, and
the gap is adjusted at each of the measurement positions to 20 mm or less.
6. The liquid removal device according to claim 5 , wherein the gap measurement device is a laser rangefinder.
7. The liquid removal device according to claim 1 , wherein
the slit nozzle is fixed, and
the steel sheet moves relatively to the slit nozzle by being moved in the movement direction by a conveyor device.
8. The liquid removal device according to claim 7 , wherein the conveyor device is a. table roll on which the steel sheet is placed.
9. The liquid removal device according to claim 7 , wherein the conveyor device is a coiling/uncoiling device including a pay-off reel that uncoils the steel sheet wound in a coil form, and a tension reel that coils, into a coil form, the steel sheet from which the liquid has been removed.
10. The liquid removal device according to claim 1 , wherein
the steel sheet is stationary, and
the slit nozzle is moved relatively to the steel sheet.
11. The liquid removal device according to claim 1 , wherein
the slit nozzle includes
a nozzle main body including the jetting port, and a gas flow channel that guides, to the jetting port, the gas that is externally supplied, and
a back face member having the nozzle back face provided to extend from the jetting port of the nozzle main body toward the downstream side in the movement direction of the steel sheet, and
the nozzle back face is a counter face of the back face member that faces the surface of the steel sheet.
12. A liquid removal method that removes liquid attached to the surface of the steel sheet by using the liquid removal device according to claim 1 , the liquid removal method comprising:
a measurement step of measuring, by the gap measurement device, a gap between the jetting port of the slit nozzle and the steel sheet;
a gap adjustment step of adjusting the gap to 20 mm or less by changing a position of at least one of the slit nozzle and the steel sheet on the basis of the measured gap; and
a liquid removal step of removing the liquid attached to the surface of the steel sheet by jetting gas from the slit nozzle to the surface of the steel sheet while relatively moving the slit nozzle and the steel sheet.
13. The liquid removal method according to claim 12 , wherein the gap is readjusted by executing the measurement step and the gap adjustment step each time a sheet thickness of the steel sheet changes.