JPH0633791B2 - Degassing device for pulp pump - Google Patents

Description

Description: [Industrial field of application] The present invention is for separating gas from a high-concentration pulp suspension (fiber suspension) containing a large amount of gas such as air and transferring only liquid. The present invention relates to a degassing device for a pulp pump.

[Prior Art] As a pump for separating and removing gas from a liquid containing a large amount of gas and feeding the liquid, a shroud of an impeller is arranged so that a central portion along the blade becomes denser and closer to a peripheral portion. It is known that a large number of gas vent holes are provided.
(See Japanese Examined Patent Publication No. 52-561) However, when the shroud of the impeller is simply provided with a gas vent hole, when applied to a high-concentration pulp suspension, pulp in the liquid is clogged in the gas vent hole. As a result, degassing is not performed properly.

Therefore, when attempting to send a liquid containing a large amount of both pulp and gas by a centrifugal pump, the pulp and liquid having a large specific gravity are pushed to the peripheral portion, and attention is paid to the gas having a small specific gravity staying in the central portion. , A space (clearance space) is provided in the center of the rotor, and a gas vent hole is provided in the vicinity of the rotation axis of the rotor so that the space is communicated with the gas chamber behind and suction removal is performed by a vacuum pump. What has been done is being developed. (Japanese Patent Sho 60-
(See Japanese Patent No. 7923) [PROBLEMS TO BE SOLVED BY THE INVENTION] As described above, the idea that the space is provided in the center of the rotor to retain the gas and the gas is sucked and removed from the vicinity of the central axis of the rotor is apparent at first glance. It seems reasonable, but when the pump is actually operated, it is true that gas remains in the central space of the rotor while the vacuum pump for degassing is stopped. When the gas is sucked from the vicinity of the rotation axis of the rotor, the pulp-containing liquid fills the space as soon as the gas is released and the pressure in the central space decreases, and as a result, not only gas but also pulp and It turned out that there is a problem that even liquid is sucked.

The reason is not always clear, but near the center of rotation of the pump blade, the rotational linear velocity is smaller than the rotational angular velocity, so the acceleration due to the centrifugal force is small and the suction force of the vacuum pump acts on the pulp-containing liquid. It is presumed that the suction force of the vacuum pump becomes larger than the centrifugal force, and as soon as the gas pressure decreases due to vacuum suction, not only the gas but also the pulp and liquid existing in the vicinity are sucked. .

In order to cope with this liquid suction, a flow path is provided to return the sucked liquid to the suction side of the main impeller, separate water and water in the cyclone impeller chamber, circulate the liquid again to the suction side, and pump only the gas into a vacuum pump. It is also proposed to suck the liquid to the side (see Japanese Utility Model Laid-Open No. 55-62894), but since the liquid containing contaminants is once sucked together with the gas, the gas vent hole is easily clogged, and the high-concentration pulp suspension is suspended. It is difficult to apply to suspensions.

The present invention, in the above-mentioned prior art, when attempting to suck and remove gas from the vicinity of the central axis of the pump blade, as soon as the gas is removed by vacuum suction and the pressure in the central space decreases, the pulp-containing liquid is discharged into the space. It was made to solve the problem that not only gas but also pulp and liquid are sucked as a result,
By changing the conventional idea that "gas accumulates in the central part, so it is only necessary to degas from the vicinity of the rotation axis of the rotor", and degas from a position away from the rotation axis rather than near the rotation axis. It is a solution to the above problems.

[Means for Solving the Problem] The present invention provides a means for solving the above-mentioned problems, and is a central part of a rotor 3 arranged in a pump chamber 2 having a cylindrical blowing port 1. Is provided with a projection shaft 3'extending in the axial direction toward the inlet of the cylindrical blow-in port 1, a screw-shaped stirring and feeding blade 4 is attached to the tip end thereof, and the projection shaft 3'base end of the rotor 3 is attached. A plurality of degassing holes 6 are arranged on the same circumference in the shroud 5 ′ of the pump blade 5 attached to the side with an array diameter Y that is substantially the same as or slightly larger than the diameter X of the cylindrical blowing port 1. A plurality of radial back vanes 7 are provided on the back side of the pump vanes 5 and are connected to the back vanes 7 to have an outer diameter substantially the same as or slightly larger than the arrangement diameter Y of the gas vent holes 6. An expeller 8 in the form of a reverse impeller having Z is disposed, Expeller 8
A degassing device for a pulp pump, which is characterized in that a throttle part 9 is provided at a rear part thereof and is communicated with a vacuum chamber 10, is a gist of the invention.

[Operation] Since the present invention has the above-described configuration, when the tip of the cylindrical blowing port 1 is connected to the high-concentration pulp suspension container and the rotor 3 is driven, the cylindrical blowing is performed from the center of the rotor 3. Inside the pump chamber 2, the pulp suspension is spirally rotated while being stirred by the screw-shaped stirring and feeding blade 4 attached to the tip end of the protruding shaft 3 ′ extending in the axial direction toward the inlet of the mouth 1. Is sent to the direction of the pump blades 5 through the cylindrical part of, and first, the agglomerate pulp is crushed into fine pieces by the stirring action, and then the centrifugal force by the spiral-shaped rotary feed action causes the solid matter having a large specific gravity to move to the peripheral portion. The gas with a small specific gravity is pushed away and gathers in the center,
In other words, in the state where the suspension density is dense in the peripheral portion and the central portion is sparse, the pump action of the pump blades 5 is exerted, and the centrifugal force is further exerted here.

On the pump blades 5, the rotational angular velocity is constant, but the rotational linear velocity increases from the central portion toward the peripheral portion, so that the centrifugal force acts more toward the peripheral portion, and the suspension containing pulp with a large specific gravity is obtained. Is discharged from the outlet 2 ', while gases such as air having a specific gravity of almost zero are collected in the central portion.

At this time, the shroud 5'of the pump blade 5 attached to the base end portion of the rotor 3 is provided with a plurality of degassing holes 6 having an arrangement diameter Y which is substantially the same as or slightly larger than the diameter X of the injection port 1. Since they are arranged on the same circumference and communicated with a vacuum source, pulp or liquid having a large specific gravity is discharged from the pump outlet 2'under the action of centrifugal force, while gas such as air having a specific gravity almost equal to zero. Is sucked out of the gas vent hole 6 by a vacuum action.

In the pump chamber 2, pulp or liquid having a large specific gravity is pushed to the peripheral portion by the action of centrifugal force, and the gas having a small specific gravity stays in the central portion, but on the pump blades 5, the central portion moves from the central portion to the peripheral portion. As the centrifugal action gradually increases and the pulp-containing liquid flows out toward the outlet 2 ′, the range where the gas exists on the pump blade 5 expands beyond the blowing port diameter X in a divergent manner.

Therefore, in the shroud 5'of the pump blade 5, the blow port diameter X
By arranging a plurality of gas vent holes 6 with an arrangement diameter Y almost the same as or slightly larger than that and communicating with a vacuum source, the gas not subjected to the centrifugal force is extracted by the vacuum action, while the centrifugal force is reduced. The pulp or liquid subjected to the action of force flows out toward the pump outlet 2 '.

The reason why the arrangement diameter Y of the gas vent holes 6 is set to be almost the same as or slightly larger than the blowing opening diameter X is that Y <X, the gas mixing ratio is high, but the centrifugal force acting on the solid matter or the liquid is unsatisfactory. Enough,
As pointed out as a problem of the conventional example, the liquid may be sucked together with the gas, and if Y> X is too large, the centrifugal force is sufficient, but the gas mixing ratio is reduced, resulting in the degassing result. Is insufficient.

According to the result of the experiment, the best degassing effect is obtained when Y≈X and Y ≧ X.

Explaining the reason therefor, as described above, the range in which the gas exists on the pump blades 5 is widened beyond the blowing port diameter X, so that the arrangement diameter Y of the gas vent holes 6 is Y≈X and Y. If> X is set, the amount of staying gas can be kept constant by appropriately controlling the amount of vacuum suction, and the gas keeps a certain volume while maintaining its divergent shape, while the liquid has a centrifugal force. Exit 2'by action
Emitted from.

Even if the gas is drawn out due to excessive suction, and the volume of the stagnant gas decreases, in that case,
Since the gas vent hole 6 is closed by the liquid and cannot be vented, the gas is in a hermetically sealed state and maintains a constant volume, and is not crushed by the liquid.

When the volume of the sealed gas is increased again by the subsequent stagnant gas, the gas vent hole 6 that was closed by the liquid is opened and the gas can be ventilated, so that the normal operation is restored.

As described above, when the gas is drawn out by excessive suction in every corner, the volume of the stagnant gas is reduced, and the gas vent hole 6 is closed by the liquid so that the gas cannot be vented, the gas is temporarily discharged from the gas vent hole 6. It is possible that the liquid containing the is sucked, but in that case, the gas and liquid are surely separated by the expeller 8 on the back side of the pump blade 5.

That is, a plurality of radial back vanes 7 are arranged on the back side of the pump vanes 5 and are connected to the back vanes 7 and have a reverse feed having an outer diameter Z that is substantially the same as the array diameter Y or slightly larger. Since the impeller-shaped expeller 8 is provided and the throttle part 9 is provided at the rear part of the expeller 8 to communicate with the vacuum chamber 10, it is possible that liquid is sucked together with gas from the gas vent hole 6 by excessive suction. Even if there is, the liquid is pushed back by the expeller 8 which is a return impeller-like return vane and is separated into gas and liquid.

At this time, the outer diameter Z of the expeller 8 is the arrangement diameter Y of the gas vent holes 6.
If it is smaller (Z <Y), there is a possibility that the pulp that has been pushed back to the corner will be sucked again and clog the expeller 8 and the throttle portion 9. However, the outer diameter Z of the expeller 8 is set to the array diameter Y.
By setting the diameter to be almost the same as or slightly larger (Z≈Y, and Z ≧ Y), the pushed-back pulp is not sucked again, and the pump is generated by the centrifugal force given by the radial back blades 7. The gas is discharged toward the outlet 2 ', and only the gas is discharged from the throttle portion 9 through the vacuum chamber 10 to the gas vent passage 11, so that a reliable gas venting effect can be obtained.

[Effect] According to the present invention, the pump chamber 2 having the cylindrical blowing port 1 is provided.
At the center of the rotor 3 disposed inside, a projection shaft 3'extending in the axial direction toward the inlet of the cylindrical blow-in port 1 is provided, and a screw-shaped stirring and feeding blade 4 is attached to the tip end thereof. , A plurality of gases having an arrangement diameter Y which is substantially the same as or slightly larger than the diameter X of the cylindrical blow-in port 1 is attached to the shroud 5'of the pump blade 5 attached to the base end side of the protrusion shaft 3'of the rotor 3. By aligning the vent holes 6 on the same circumference, the gas not subjected to the centrifugal force is extracted from the gas vent hole 6, while the solid matter or the liquid subjected to the centrifugal force is discharged to the pump outlet 2 '. Since it flows out toward the outside, the gas vent hole 6 is not clogged with a fixed object.

Even if the gas is drawn out due to excessive suction, and the volume of the stagnant gas decreases, in that case,
Since the gas vent hole 6 is closed by the liquid and cannot be vented, the gas is in a hermetically sealed state and maintains a constant volume, and is not crushed by the liquid. When the volume of the sealed gas is increased again by the subsequent stagnant gas, the gas vent hole 6 that was closed by the liquid is opened and ventilation is possible, and normal operation can be restored.

At this time, even if the liquid containing gas is sucked from the gas vent hole 6, a plurality of radial back blades 7 are arranged on the back side of the pump blade 5 and are connected to the back blade 7. An expeller 8 in the form of a reverse-feeding impeller having an outer diameter Z that is substantially the same as or slightly larger than the arrangement holes Y of the gas vent holes 6 is provided, and a throttle portion 9 is provided at the rear of the expeller 8 to provide a vacuum. By communicating with the chamber 10, gas-liquid separation is performed and a reliable degassing effect is obtained. Therefore, gas is separated from a high-concentration pulp suspension (fiber suspension) containing a large amount of gas such as air, and only liquid is obtained. It is suitable as a degassing device of a pulp pump for transferring the

[Brief description of drawings]

FIG. 1 is a sectional view of a pulp pump provided with a degassing device of the present invention, and FIG. 2 is a back view of pump blades. 1: Cylindrical injection port 2: Pump chamber 2 ': Pump chamber outlet 3: Rotor 4: Stirring and feeding blade 5: Pump blade 5': Pump blade shroud 6: Gas vent hole 7: Back blade 8: Expeller 9: Throttle part 10: Vacuum chamber 11: Gas vent passage

Claims (1)

[Claims] 1. The cylindrical blower port (1) is provided at the center of a rotor (3) arranged in a pump chamber (2) having the cylindrical blower port (1).
A projection shaft (3 ') extending in the axial direction toward the inlet of the rotor is provided, and a screw-shaped stirring and feeding blade (4) is attached to the tip end of the projection shaft (3') On the shroud (5 ') of the pump blade (5) mounted on the side, a plurality of gas vents are provided with an array diameter (Y) that is approximately the same as or slightly larger than the diameter (X) of the cylindrical inlet (1). The holes (6) are aligned on the same circumference, a plurality of radial back vanes (7) are arranged on the back side of the pump vanes (5), and the gas is connected to the back vanes (7). A reverse feed impeller-shaped expeller (8) having an outer diameter (Z) that is almost the same as or slightly larger than the arrangement diameter (Y) of the holes (6) is arranged, and the throttle is provided at the rear of the expeller (8). A degassing device for a pulp pump, which is provided with a part (9) and is communicated with a vacuum chamber (10).