Pneumatic Pulsator For Imparting Vibratory Motion To Liquid In A Container

Abstract

A pneumatic pulsator is provided for imparting vibratory motion in a liquid in a container, and the pulsator comprises a rotatable slide valve in the form of a disc, housed in a body with an inlet port and exhaust port, the disc having one or more holes or slots for periodically providing communication between the liquid in the container with a compressed air line or the atmosphere. The container is connected to the exhaust port by an outlet pipe which is coaxial with the exhaust port.

Description

The present invention relates to pneumatic pulsators employed for imparting vibratory motion to liquid in a container, particularly chemical apparatus, such as columns reaction vessels, mixers-settlers etc.

The vibratory motion of the liquid serves to intensify the proceeding processes and is effected by alternative supply and release of compressed air into a pulsating chamber of the apparatus by means of a pulsator, said chamber communicating with the liquid container through a hole, located below the liquid level.

The volume of the liquid acquiring vibratory motion may vary from 0.1 to 100 m..sup.3 and the amount of air supplied into the container in one working stroke may vary from 0.1 to 2 m..sup.3 at a pressure of 0.1 to 3 atm.

As a rule, the known pulsators have an adjustable-speed drive for rotating a slide valve located in a body, said slide valve providing communication between the pulsating chamber of the apparatus alternately with a high-pressure line, connected to a compressed air source, and to the atmosphere. This results in the production of vibratory motion in the liquid in the container.

Usually, the slide valve essentially comprises a cylindrical member with through channels, whose body communicates, through a pipe, with the container of the apparatus and has an inlet port and an exhaust port, the inlet port communicating with the compressed air line and the exhaust port with the atmosphere.

Depending on the volume of the liquid in the apparatus and on the amplitude of vibration, various-size slide valves are employed (40 to 600 mm. diameter) with particular cross sections and channel lengths, as it is necessary to ensure a required volume of the exhaust compressed air, supplied into the apparatus during one working stroke, when the volume of the air line, periodically filled with air, and the amplitude of the liquid pulsation are changed.

When employing large-size slide valves it is difficult to ensure reliable lapping of the surface of the slide valve assembly (that is, the surface of the slide valve and the body), which results in increased air leakage, and increased air consumption which adversely affects the economy of the process and the stability of the vibration conditions.

Additionally, the channels of these slide valves are comparatively long and consequently they provide considerable hydraulic resistance. Therefore during the period of time when the slide valve communicates with the atmosphere, the entire volume of the air has no time to escape from the apparatus through the outlet pipe. This results in reduced amplitude of the liquid vibration in the apparatus, which in turn decreases the process intensification.

An object of the present invention is to provide an improved pneumatic pulsator with such a shape of the slide valve and location of the outlet pipe, communicating the chamber with the atmosphere, which will allow elimination of the undesirable phenomena mentioned hereinabove.

The invention is directed to a pneumatic pulsator for imparting vibratory motion to liquid in a container, said pulsator being provided with a rotatable slide valve, accommodated in a body with an inlet port and an exhaust port, and periodically communicating the container with the compressed air line and atmosphere. According to the invention, the desired object is achieved by constructing the slide valve in the shape of a disc with at least one hole therein and by coaxial location of the outlet pipe, communicating the container with the atmosphere, and the exhaust port in the slide valve body.

If the disc has several holes, some of which periodically communicate with the inlet port and others with the exhaust port, it is expedient to locate these holes along concentric circumferences of the disc.

An advantage of the invention lies is that due to the disc shape of the slide valve, the surfaces of the slide valve assembly need be lapped only at the places of location of the body ports and slide valve holes.

Another advantage of the invention is that a small hydraulic resistance is produced during the air exhaust which is due to the short air passage, determined by the disc thickness, and also due to the coaxial location of the outlet pipe and exhaust port in the slide valve body.

The above mentioned advantages allow reduction of air leakage, and ensure the process stability and its effectiveness due to the reduction of the air consumption.

Next the invention will be further described by way of examples with reference to the appended drawing wherein:

FIG. 1 is a diagrammatic elevation view of a pneumatic pulsator, communicating with a liquid container, according to the present invention,

FIG. 2 is a top plan view of the same pneumatic pulsator with the container.

FIG. 3 is a sectional view of a slide valve, according to the invention, and

FIGS. 4 to 8 show a cross section of the slide valve, according to the invention, with different location of inlet holes and exhaust holes, the location of the inlet port of the body and the exhaust port being shown conventionally.

As shown in FIGS. 1 and 2, the pneumatic pulsator has a frame 1 for the joint installation of a motor 2 and a reduction gear 3, whose output shaft 4 is connected to a slide valve 5, housed in a body 6. The body 6 is connected, through a pipe connection 7, to a receiver 8 which communicates with a compressed air line 9 and, by means of an inlet pipe 10 and exhaust pipe 11 to a common pipe 12 and further to a pulsating chamber 13 of a liquid container 13a.

The slide valve 5 (FIG. 3), connected to the output shaft 4 of the reduction gear, is constructed as a disc with several inlet and exhaust holes 14 and 15 respectively, by means of which the slide valve periodically connects the pulsating chamber 13 of the container 13a with the compressed air line 9 and with the atmosphere through respective inlet and exhaust ports 16 and 17 in the body 6, as a result of which the liquid in the container 13 undergoes vibratory motion.

It should be emphasized that in spite of the fact that the pulsating chamber 13 is periodically subject to overpressure, the liquid in the container 13a is usually under atmospheric pressure. This considerably improves the reliability of such apparatus and simplifies its design. However, in a general case the pressure in the apparatus depends on the conditions of operation and may be other than atmospheric.

As shown in FIG. 3, the outlet pipe 11 is located coaxially with the exhaust port 17 in the body 6, which is efficient from the point of view of reducing the hydraulic resistance during the exhaust.

Installed between the slide valve 5 and body 6 on the side of the input shaft 4 at the place of location of the inlet port 16 and the exhaust port 17 are stationary sealing circular liners 18 and 19 made of a wear resistant material, such as, graphite or Teflon. A clearance (not shown) is left between the faces of the liners and the disc, said clearance having been formed as a result of preliminary lapping.

The circular liners also reduce air leakage.

The number of communicating holes in the slide valve, their shape and cross sectional area are determined by the ratio between the duration of the air inlet stroke and air exhaust stroke, as well as by the frequency of vibrations and other factors.

In the simplest case the slide valve 5 has one communicating elongated hole or slot 20 (FIG. 4), alternately registering with the inlet port 21 and the exhaust port 22 of the body during rotation of the slide valve. It is evident that in this case the duration of the air inlet stroke and exhaust stroke is the same.

The same configuration of the liquid vibrations in the container can be obtained when there are two holes 23 and 24 (FIG. 5) in the slide valve 5, one of said holes periodically communicating with the inlet port 25, while the other periodically communicates with the exhaust port 26 of the body, the holes 23 and 24 being located along concentric circumferences of the disc.

A changed configuration of the liquid vibrations can be also obtained when there are two holes 27 and 28 (FIG. 6) in the slide valve, said holes being located along concentric circumferences of the disc, where the exhaust hole 28 has a larger cross section area. In this case the air inlet stroke is short and the exhaust stroke is long, as the time of communication of these holes with the inlet port 29 and the exhaust port 30 of the body is not the same.

In order to prevent the slide valve from undergoing excessive wear by reducing its r.p.m. and increasing the number of vibrations, the slide valve is made with several pairs of inlet holes 31 and exhaust holes 32 (FIGS. 7 and 8), located along concentric circumferences of the disc and communicating alternately with the inlet port 33 and the exhaust port 34 of the body.

The present invention is not confined to the embodiments described hereinabove and they can be modified without departing from the scope of the invention as defined hereafter in the appended claims.

Claims

What we claim is:

1. A pneumatic pulsator for imparting vibratory motion to liquid in a container, said pulsator comprising a compressed air supply line; a body with an inlet port and an exhaust port, said inlet port communicating with said supply line, said exhaust port communicating with the atmosphere, a slide valve comprising a disc with hole means therein, said disc being rotatably housed in said body between the container and the inlet and exhaust ports, said hole means being located in said disc to be in periodic communication with said inlet and exhaust ports during rotation of the disc and provide periodic connection of the container with the compressed air supply line and with the atmosphere; means for rotating said slide valve; and an outlet pipe connected to the container and to the body coaxially with said exhaust port such that said outlet pipe is in communication with the atmosphere when the hole means in the disc is in registry with the exhaust port.

2. A pneumatic pulsator as claimed in claim 1, wherein said hole means in said disc is constituted by a plurality of holes, some of which periodically communicate with the inlet port in the body, while others communicate with the exhaust port, the holes being located along concentric circumferences in the disc.

3. A pneumatic pulsator as claimed in claim 2 wherein said holes are constituted as circumferential slots extending along respective concentric circles in the discs.

4. A pneumatic pulsator as claimed in claim 2 wherein at least one of said holes is constituted as a circumferential slot.

5. A pneumatic pulsator as claimed in claim 1 comprising a connecting pipe between the body and outlet pipe and providing communication between the outlet pipe and the inlet port when the hole means in the disc is in registry with said inlet port.

6. A pneumatic pulsator as claimed in claim 1, wherein said body is hollow and said disc is mounted therein to block connection of the inlet port and exhaust port with the container except when the hole means is in registry with said ports.

7. A pneumatic pulsator as claimed in claim 1, wherein said hole means is constituted by at least one circumferential slot.