JPS62503109A - Rotating elements used in screening devices with contoured surfaces - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention mainly involves screening pulp, more specifically, paper pulp. and screening devices intended to be used for purification. do.

This screening device includes a body and a cylindrical screen housed inside the body. a rotor moving near the screen surface and a screened pattern. There is an inlet for putting in the liquid, an outlet for discharging things that cannot be put in, and a receiver. Take out the screened pulp, which is called the stuff that can be put in. It consists of a separate exit for the.

U.S. Patent Serial No. 472,742 includes a It is equipped with an inlet to introduce the unprocessed pulp and a receptacle on the opposite side. A cylindrical screen plate with an outlet to take out the pulp part that cannot be route is explained. unscreened pulses along the first direction of flow; Means are provided for moving the pool. Screen plate is the screen surface A groove is provided on the side of the inlet recessed in the groove, and the first direction of flow is approximately transverse with respect to the groove. It is possible. The groove is formed by an upstream side surface, a downstream side surface, and a bottom surface.

The bottom surface extends approximately parallel to the envelope surface of the screen plate. The groove is padded on the bottom. - Equipped with horations.

When viewed from the bottom of the groove, the upstream side extends almost perpendicular to the envelope surface. The downstream side of the groove forms an angle ranging from 60° to 5° with respect to the envelope surface. has been completed. According to a preferred embodiment, the downstream side of the groove and the screen plate The angle between the envelope surface and the envelope surface is approximately 30°. This configuration is called a “contour profile”. It's been revealed.

In the papermaking process, pulp is made by treating wood to separate it into fibers. same Even from the same tree, wood with different properties is obtained, so the fibers are not separated. Any debris or broken pieces that have formed an object that cannot be placed in the receptacle. Rui are dispersed as fiber bundles commonly called lobes. Other than that, remove There are also impurities like bark that must be present. Screen can be accepted It is capable of accepting unwanted impurities and debris, also known as waste. It must be separated from the exposed parts. It can be accepted together with debris. efficiency to avoid large losses of fibers that could be transferred to areas where It is necessary to remove impurities selectively.

It must be emphasized that different applications impose different requirements. There is no such thing. Long fibers among those that can be accepted depending on the application , in particular it may be necessary to increase the content of secondary fibers.

This is because long fibers are what give strength to the final product, e.g. paper. It is. On the other hand, in other applications the opposite is true. For example, virgin fiber or In the case of pulp or mill fibers, the receivers go to great lengths to refine what they cannot accept. It is desirable to concentrate the fibers.

A lot of research has been done in connection with screen plates and rotors. It has been confirmed that the means of generating pulsations in the motor increases the efficiency of the device. ing. U.S. Patent No. 3;363,759 and U.S. Patent No. 4.318,80 No. 5 discloses a drum rotor with a pulsating bumping surface. There is. In U.S. Pat. No. 4,318,805, the collision part is a head with a larger diameter. It takes the form of a pin protruding from the rotor with a Generates pulsation without providing resistance.

Specifications of U.S. Patent No. 4,447,320 and U.S. Patent No. 4,200,537 is a plaid or blade moving near the screen that produces large negative pulses. A rotor carrying a horn is disclosed. Other patents open other types of rotors. It shows. For example, U.S. Pat. No. 3,726,401 and a rotor with bumps or protrusions that generate negative pulses.

According to the patent, any type of bulb that produces the required pulses can be used. It can also be used at the resting part, and the bumping part and the indentation between the bumping parts are positive. Generates a screening pressure pulse and a negative screen cleaning pressure pulse.

U.S. Pat. No. 3,400,820 describes a plurality of independent segments connected to each other. selected waves that generate approximately the same positive and negative pulses. A rotating member that forms a pattern is disclosed.

One of the purposes of the present invention is to provide a This prevents the formation of blockages and thereby reduces the flow of the fiber suspension through the screen openings. in the screen plate to generate the negative pulse needed to increase the Increase the intensity of the pulses generated near the aperture, i.e., the orifice or slot. The objective is to provide a rotating element that increases the

Another object of the invention is that, in addition to having sufficient amplitude, very high frequency pulses The objective is to provide a rotating element that generates energy.

Another object of the invention is to generate sharp, steep negative pulses, so that The objective is to provide a rotating element with high pulse strength.

Yet another object of the invention is to reduce power requirements.

Another object of the invention is to operate the screen using a relatively small orifice. and therefore provide a rotor that can increase screening efficiency. It is to be.

Yet another object of the invention is to obtain as close as possible the consistency of the pulp introduced into the inlet. The objective is to obtain an acceptable portion with a high density.

Another object of the invention is to avoid sorting long fibers, e.g. , where a relatively large inlet screening area is preferred and the rotor Used in place of a rotor in certain applications where a continuous surface is not desired. The objective is to provide plaid type segments that are

Yet another object of the invention is as described in U.S. Patent Serial No. 472.742. Advantageously used in conjunction with the claimed screen plate The objective is to provide a flexible rotor and plaid type segment.

Now, the rotor surface and plaid type segment characteristics listed below. The constant shape produces a relatively high pulse of 9 strength, while also producing a sufficiently negative pulse. It is particularly advantageous to minimize screen clogging. It became clear that it was possible.

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings. here, Figure 1 shows a conventional pressure pump using a rotating hydrofoil to create pulses. This is an illustration of the screen.

Figure 2 shows the pulses produced by the rotating hydrofoil shown in Figure 1. It is illustrated.

3 and 3a illustrate the contoured surface of a rotor according to the invention.

FIGS. 4 and 4a show the contoured surfaces according to the invention shown in FIGS. 3 and 5. Characteristics of pulses made from rotor or plaid type segments It is illustrated.

FIG. 5 shows a plaid type with a contoured surface according to the invention instead of a rotor. Fig. 3 illustrates an example of a segment of .

FIG. 6 is a screen playback according to U.S. Patent Serial No. 472,742. shows the contour profile of the root.

Figure 7 shows the strength, which is the ratio of the change in amplitude per unit time for a conventional rotating element. This is an illustration of the factors.

Figure 7a illustrates the strength factor for the rotating element according to the invention. be.

FIG. 8 compares the pulse profiles of a conventional rotor and a rotor according to the present invention. This is a comparison.

As shown in Figure 2, a single rotation hydrofoil has negative and positive pulses. Both occur. Pressure at symbol 0 is applied to the rotating foil and screen series. The value of the pressure in the vicinity of the screen surface or screening area between the represent. When the pressure of the pulp is higher than the standard zero point, the pressure reaches its maximum value at point A. and when the pressure is lower than the reference point, the pressure has a negative value and this negative value is It is maximum at point B.

The rotating hydrofoil shown in Figure 1 is well known in this technical field. generates the pulses shown in FIG. High as shown in the drawing The front or leading edge of the drofoil has approximately the minimum gap between the foil and the screen. Generates a positive pulse with maximum value or amplitude at a point. This positive pulse flow into the screening area through the openings in the screen. It will be done. This is because flow always occurs from areas of high pressure to areas of low pressure. It is from. However, behind the minimum foil gap point, the foil The two most negative pulses occur because the slope of Il Plaid is changing. 1st As shown in the figure, the angle of this slope for most foil plaids is It is about 30'' or even looser.

After the maximum negative pulse point, the pressure increases again to the reference zero point at zero revolutions. Due to the negative pulse caused by the hydrofoil A momentary backflow or backflow through the orifice will occur, eliminating any fiber blockages located in the orifice. It can be set aside. The greater this automatic cleaning effect, the greater the , the negative pulse becomes larger.

rotor and plaid type segment fins well known in this technical field. The foil or lobar surface or protrusion has an anterior surface, the anterior surface comprising: curve towards the screen cylinder until the minimum rotor clearance point is obtained. There is. The rear surface behind the front surface is curved away from the screen. ing. At the point of minimum rotor clearance the change in slope of the curved surface is zero. of this point Immediately after, the magnitude of the negative pulse begins to increase to its maximum negative value, and then The signal begins to decrease again and the cycle repeats, as shown in Figure 2. be done.

The gist of the invention is that a groove has a contoured surface formed from a first surface parallel to the envelope surface; Rotor and plaid type segment consisting of an inclined surface, a top surface and a side surface the side surface extends substantially perpendicularly to the first surface, and the inclined surface of the groove extends substantially perpendicularly to the first surface; forming an angle in the range of 30° to 60° with respect to the first surface; rotor and plaid-type segments configured to extend parallel to the plane of The goal is to provide the following. According to a preferred embodiment, the inclined surface of the groove is shaped with respect to the first surface. The angle formed is 45°.

Referring to Figures 3 and 3a, reference numeral 1 indicates the first side and reference numeral 2 indicates the inclined surface. Indicating a slope, reference numeral 3 indicates the top surface and reference numeral 4 indicates the side perpendicular to the first surface. show.

Reference numeral 6 indicates the envelope of the screen.

Referring to FIG. 5, the same reference numerals 1, 2, 3 and 4 refer to the first surface, the inclined surface and the top surface. Used to indicate a side surface extending perpendicular to the first surface.

As shown in Figure 3a, when viewed from the reference point A, the front surface is parallel to the envelope surface. It has a surface 1. The front surface is inclined while forming an inclined surface 2 and reaches an upper surface 3.

The length of the top surface 3 must be set between 1/4 inch and 3 inches. . Behind the top surface the groove is provided with side surfaces 4 extending perpendicularly to the first surface 1. first The length of surface 1 may vary from 0 to 3 inches.

This feature of the side surface 4, which is almost perpendicular to the bottom surface, makes the screen Generates an effective pulse to prevent the tube from becoming clogged. This is important in order to

FIG. 4 shows a pulse generated from a rotating element with a contour profile according to the invention. This is an illustration. Very sharp negative pulses on the rotor surface or Occurs at a 90″ angle to the raid type segment. This is more Also within the gap point of small rotor or plaid type segments. The flow path of the fluid is related to the Bernoulli effect that occurs as the velocity of the fluid increases. This is because things change rapidly. The pulsation changes violently or quickly like this. The rotor or plaid type segments are more effective during the Maximum velocity and acceleration of fluid passing through the aperture using conventional pulse-generating rotating elements The above effect can be explained on the basis that can. Because the change in pulse or amplitude with respect to time is, for a contoured surface, This is because it is very large (see Figure 4a).

The term "pulse intensity" within the scope of the present invention refers to the number of pulses per unit time. It is intended to mean a change in amplitude. To explain this matter in other words, Pulse strength is not only a result of amplitude, but also depends on rapid and sharp changes . For the strength factor IF, see unit time figures 7 and 7a).

As can be seen by comparing FIG. 4 with FIG. 2, FIG. The rotating element according to the invention having a contoured surface is superior to that of the plaid type. Which indicates that. Additionally, the slope and front surface of the contour rotation element generate positive pulses. This positive pulse causes the flow of the fibrous suspension through the openings in the screen. The induction of is promoted. The top surface 3 is connected to the side surface 4 to cause rapid changes in pulsation. This is something that is needed last minute.

Figure 5 shows that the material at the entrance fills the entire screening area, so the receiver is In addition to minimizing the concentration of long fibers in materials that cannot be In order to be able to minimize the density of things that cannot be Therefore, a large screening area with a large open area is desirable; Figure 2 illustrates an embodiment configured to accommodate longer fibers. It is. In this embodiment, a play with a contoured surface instead of a rotor is used. segment is used.

A ring of segments of the rotor or plaid type, which is a rotating element according to the invention The wall surface generates high frequency pulsations. For example, if the rotation speed is 600, 2 It is possible to obtain pulsating frequencies of 0.00 Hz and much higher. The frequency is Being expensive is an advantage. This is because the fibers tend to block holes less and This is because the amplitude of the pulse is sufficiently large to cause backwashing. even higher frequency The screen can handle even more concentrated feedstocks.

As is clear from a comparison between FIG. 7 and FIG. 7a, compared to the conventional rotating element, the present invention The strength factor obtained with the rotating element is excellent. See Figure 8 The pulse profile of a conventional hydrofoil is then shown as a dashed line. , the pulse profile of a rotor with a contoured surface according to the invention is shown as a solid line. It is.

Another advantage of the rotor and plaid type segments of the present invention is that they reduce power dissipation. The size of the screen aperture can be made sufficiently small without increasing the cost. Since it is possible and does not involve significant loss of long fibers, it is possible to The yield of the parts that can be produced is high. The density of what can be put in is , the density of the raw material at the inlet can be kept at approximately the same level.

The rotor shown in Figure 3 and the plaid type segment shown in Figure 5. can be used in conjunction with conventional screen plates and In accordance with U.S. Patent Serial No. 472,742, shown in FIG. Also used in conjunction with screen plates with configured contour profiles. can be done.

FI3. I B FI[5,2 FIG.3 FIG.4 FIG. 4a F I G, 6 FIG.7 FIG, 7α

Claims (10)

[Claims] 1. A body, a cylindrical screen housed within the body, and a groove formed in the screen. a rotating element moving in the vicinity of the screen at a predetermined speed; Inlet for uncleaned pulp and screening in said barrel an outlet for the pulp, the outlet being in operative communication with the screen; In an apparatus for screening pulp consisting of a contoured surface having grooves formed from a first surface substantially parallel to the envelope surface of the curve; a top surface, and a side surface, the side surface extending substantially perpendicularly to the first surface. and the inclined surface is between 30° and 60° with respect to the first surface. and the upper surface extends substantially parallel to the first surface. Featured device. 2. Device according to claim 1, characterized in that the rotating element is a rotor. . 3. Claims characterized in that the rotating element consists of blade-type segments. A device according to scope 1. 4. Claims characterized in that the angle between the inclined surface and the first surface is approximately 45°. Apparatus according to paragraph 1. 5. Claim 1, wherein the length of the first surface is from 0 to 3 inches. The device according to item 1. 6. Claims characterized in that the rotor extends above the surface of the screen. Screen device of item 2. 7. Claims characterized in that the rotor extends above the surface of the screen. 3. The screen device according to item 3. 8. A screen is housed in a cylindrical screen plate, and the screen The lean plate has grooves on the side of the inlet recessed into the surface of the screen. Both have an envelope surface, and when viewed with the groove rising from the bottom of the groove. It is formed from an upstream side surface, a downstream side surface, and a bottom surface, and the bottom surface is a screen. The groove extends approximately parallel to the envelope surface of the plate, and the groove is perforated on the bottom surface. an upstream side surface of the groove extends substantially perpendicular to the envelope surface; the downstream side of the groove forms an angle with the envelope surface ranging from 60° to 5°; 2. A device according to claim 1, characterized in that: 9. In the screen plate, the downstream side of the groove is the surface of the screen plate. as claimed in claim 8, forming an angle of approximately 30° with respect to equipment. 10. In the screen plate, the downstream and upstream sides of the groove are close to the envelope surface. Claim 8, characterized in that they are connected to each other via surfaces extending substantially parallel to each other. Equipment described in Section.