JPH07102495A - Cylindrical drier - Google Patents

Abstract

PURPOSE:To provide a cylindrical drier capable of being stably and efficiently driven. CONSTITUTION:A drain-discharging mechanism having plural rotary siphons distributed in the circumferential direction of a drum is disposed in a rotation cylinder. A valve mechanism for opening or closing the siphon with the gravity weight and a centrifugal force is disposed in the drain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drainage device, and more particularly to a siphon of a cylinder dryer used in a dryer in a papermaking process.

[0002]

2. Description of the Related Art In the drying process (dry part) of a paper machine, steam is heated inside a cast iron cylinder, and wet paper is brought into contact with the surface of the cylinder to dry it. At this time, it is important to smoothly and completely drain the drain staying in the cylinder. If the drain is not discharged reliably, a temperature difference that fluctuates over time will occur on the cell surface, causing uneven drying of the product,
It may also cause curling of the product. In any case, reliable drainage of the drain from the inside of the cell is the basis for papermaking of high-quality paper products with less habit and energy saving of the paper machine.

Conventionally, as a drain discharge system in a cylinder dryer used for a dryer in a papermaking process, a bucket system is usually used for a low speed paper machine and a siphon system is used for a high speed paper machine. The bucket system uses the scooping action of the bucket due to the rotation of the dryer cylinder, so no pressure difference is required to discharge the drain, but its discharge capacity is determined by the rotation speed of the dryer cylinder.

The siphon system discharges the drain to the drain header outside the dryer cylinder by the action of the vapor pressure and the flow of the flowing steam through the siphon pipe immersed in the drain, and there are the following two types. (A) Fixed siphon The siphon pipe is fixed while being insulated from the rotation of the dryer cylinder, and the drain is bonded or cascading 250 to 300 m / mi.
It is often used for paper machines with n speed.

(B) Rotating siphon The siphon pipe rotates together with the dryer cylinder. It is used for paper machines with a papermaking speed of 400 m / min or more where drainage forms rimming. Bucket method is used for low speed machines and siphon method is used for high speed machines.
Fixed siphon, about 400 in the range of around 0 m / min
At m / min or higher, a rotary siphon is used.

Conventionally, the drain discharge mechanism of the rotary siphon type dryer is generally constructed as shown in FIG.
When the dryer is stopped at any position when the cylinder dryer is stopped, if the drain suction port of the rotary siphon faces upward as shown in FIG. 5, the drain will be collected up to the suction port.

When starting in this state, the starting torque becomes excessive, the motor becomes overloaded, uneven rotation occurs even if it can be started, it takes a long time to pass the paper, and the paper is frequently out. This will cause problems. Also, as a sinter lock, even if the steam inlet valve is fully closed, there is a possibility that the valve will accumulate train due to leakage.

Therefore, under the present circumstances, the operator actually stops while monitoring so that the siphon suction port is at the bottom (the manhole of the cylinder dryer is at the bottom). In drain discharge during dryer operation, the siphon tube has only one location in the circumferential direction (about two locations in the width direction), drain discharge is poor, and temperature unevenness occurs, causing uneven drying of the paper.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary siphon type, cylinder dryer drain discharge device that can operate stably and efficiently.

[0010]

According to the present invention, in a rotary siphon of a cylinder dryer, a valve for turning on / off the flow rate of a suction drain in a siphon tube and an adjustment for pressing the valve from the suction port toward the center of the cylinder. The drain discharge device is characterized by being provided with a possible spring, and is characterized in that two or more siphon pipes are provided at substantially equal intervals in the cylinder circumferential direction.

[0011]

When the cylinder dryer is stopped at any position, the valves (A) and (B) are closed, and no air leaks. The valves (C) and (D) are open by virtue of their own weight, overcoming the spring, and the drain is discharged. In this case, the height of the drain is R (2 ^-1/2 -1) at the maximum, and the above-mentioned problem is solved. The larger the number of siphon tubes, the smaller the amount of residual drain.

When the cylinder dryer rotates, the valves A, B, C and D are pushed out to the periphery by centrifugal force, and the valves open. On the other hand, since the drain also forms a rim on the circumference as shown in the right figure, the drain is discharged from the siphon on the entire circumference, so that temperature unevenness does not occur.

[0013]

FIG. 1 is a schematic configuration diagram of a cylinder dryer drain discharge mechanism according to one embodiment of the present invention. (1) is a dryer cylinder for drying wet paper running by being pressed by a canvas, and (2) is A rotary shaft of the cylinder drum, (3) is a rotary siphon for sucking drain accumulated in the cylinder drum, and (4) is a lead-out pipe for guiding the drain sucked from the siphon to the outside of the cylinder, which is usually provided on the rotary shaft of the cylinder. (5) is a steam inlet pipe for supplying steam into the cylinder, (5A) is a cock, and (6) is a drain pipe, and a mixture of the drain liquid and the steam sucked from the siphon is discharged through the outlet pipe (4). ) And is discharged from the discharge pipe (6).

A plurality of siphons (3) are provided radially (in the radial direction) around the rotation axis of the cylinder at substantially equal intervals on the circumference, for example, a few siphons as shown in FIG. Each siphon (3A), (3B), (3C),
In (3D), as shown in FIGS. 3 (a) and 3 (b) in an enlarged manner, a suction port (31) having an open tip is formed at one end, and a drain outlet pipe (31) is formed at the other end. The throttling part (32) connected to 4) forms a valve seat, and the outer diameter of the metal ball (3) is slightly smaller than the inner diameter of the cylindrical part (30) of the siphon.
3) is housed and forms a ball valve with the valve seat (32). The ball (33) is held by the holding portion (35) via an elastic body (34) such as a spring, and can smoothly slide in the pipe of the siphon (3) in the length direction thereof, so that the ball seats on the valve seat. The valve is configured to be closed in the state of being pressed by, and to be opened when the ball pushes the spring and moves toward the suction port. In addition, the radial siphon mechanism of FIG.
It is desirable to provide a plurality of sets, for example, 2 to several sets, at appropriate intervals in the axial direction of the cylinder. (See Figure 1)

Next, the operation of the device of the present invention will be described. (A) When the dryer cylinder is stopped In FIG. 3, the mass of the ball (33) is M, the acceleration of gravity is g, the natural length (initial length) of the spring (34) is L ₀ , and the length when expanded and contracted. Let L be the spring constant, K be the spring force, F _{1 be} the spring force, W be the gravity acting on the weight, and F ₂ be the spring length component of the gravity.

F ₁ = K (L ₀ −L) (1) W = Mg (2) F ₂ = W cos θ = Mg · cos θ (3) Now, the inclination angle θ of the siphon, Assuming that the weight of the ball and the force of the ball are balanced at the spring length L, F ₁ = F ₂ (4) Therefore, K (L ₀ −L) = Mg · cos θ (5) L is calculated from L = L ₀ − (Mg · cos θ) / K (6) This force is balanced and the spring length when the ball closes the throat is L ₁ , the inclination If the angle is θ ₁ , then K (L ₀ −L ₁ ) = Mg · cos θ ₁ (7)

From this, a) If 0 <θ <θ _1, then L <L ₁ , that is, there is a gap in the throat. b) If θ ₁ ≦ θ, L = L ₁ , that is, the throat is closed. Since θ ₁ can be set arbitrarily by selecting K, if K is adjusted so that θ = 60 ° and four siphons with this mechanism are installed every 90 °, Even if the cylinder is stopped at any position, two or one siphon will be within ± 60 °.

The throat of the siphon in this range is
Since it is free, drainage can be efficiently discharged, and the siphon throat outside this range is closed,
There is no leak of pressurized air. In order to reduce the remaining amount of drain, the number of siphons should be increased and the spring should be adjusted to reduce θ ₁ .

(B) When the dryer cylinder is rotating As shown in FIG. 4, (1) and (3) in the case of the stationary state described above.
In addition to F ₁ and F _{2 in} the equation, centrifugal force F ₃ in the following equation (8) is applied. F ₁ = K (L ₀ −L) (1) F ₂ = Mg · cos θ (3) F ₃ = Mrω ² (8) However, r: centered on the cylinder axis Radius of rotation of ball ω: Same as above Angular velocity of rotation Now, assuming that the spring force F ₁ is balanced with the sum of F ₂ and F ₃ , F ₁ = F ₂ + F ₃ (9) Therefore, ( From the equations (1), (3) and (8), K (L ₀ −L) = Mg · cos θ + Mrω ² L = L ₀ − (Mg · cos θ) / K−Mrω ² / K (10) Centrifuge Since the force component acts in the direction of making L smaller than that at the time of rest, the throat is rather opened further, and the drain discharge is performed more and more efficiently.

[0020]

EFFECTS OF THE INVENTION According to the present invention: 1) Regardless of the rotation angle position of the dryer cylinder, the retention of drainage can be suppressed within the minimum limit, stabilizing the operation of the papermaking dry part and stabilizing the paper quality. , Help improve energy efficiency. 2) When the rotation of the dryer cylinder is stopped, it is not necessary to stop the dryer cylinder at a specific angle, so a control mechanism therefor is not particularly required. 3) Also, unlike the case where the stop angle is set by the operation of the operator, it does not require manual labor and meticulous attention for that, which is useful for labor saving. 4) Also, due to operation mistakes or equipment errors, a large amount of drain will accumulate in the cylinder during the stop period, as in the case of stopping at an incorrect rotation angle position, which will cause trouble at the next start. There is no fear. 5) Since the siphon suction ports are distributed over the entire circumference of the cylinder, the temperature distribution on the outer circumference of the drum becomes uniform, which is also effective for improving paper quality.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cylinder dryer according to an embodiment of the present invention.

2A and 2B are schematic configuration and operation explanatory views of a drain discharge mechanism of the device of the present invention in FIG. 1, particularly a rotary siphon, in which FIG. 2A shows a stationary state and FIG. 2B shows a rotating state.

FIG. 3 is a detailed configuration / operation explanatory view of the siphon mechanism in FIGS. 1 and 2.

FIG. 4 is a diagram for explaining the operation of the valve mechanism of the siphon mechanism of the present invention.

FIG. 5 is a diagram showing a configuration example of a conventional cylinder dryer drain discharge device.

[Explanation of symbols]

 1 Cylinder Drum 2 Rotating Shaft 3 Rotating Siphon 4 Drain Outlet Pipe 5 Steam Supply Pipe 6 Train Discharge Pipe 30 Siphon Cylindrical Part 31 Siphon Inlet 32 Siphon Valve Seat 33 Ball 34 Spring 35 Holding Part

Claims (4)

[Claims] 1. A cylinder dryer having a drain discharge mechanism in which a plurality of siphon tubes are distributed in a circumferential direction of a drum in a rotary cylinder drum. 2. The cylinder dryer according to claim 1, wherein three or more siphon tubes are provided at substantially equal intervals in the circumferential direction of the drum. 3. In a rotary siphon of a cylinder dryer, a suction drain flow rate of O is set in the siphon tube.
4. The cylinder dryer according to claim 3, further comprising an N-OFF valve and an adjustable spring that presses the valve from the suction port toward the center of the cylinder. 4. The cylinder dryer according to claim 3, wherein the opening and closing of the valve is mainly controlled by gravity when stationary and by centrifugal force when rotating.