AU737929B2 - Pump system - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): ENVIROTECH PUMPSYSTEMS NETHERLANDS B.V.

Invention Title: PUMP SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me/us: Title: Pump system.

The invention relates to a pump system in particular suitable for pumping hot media, such as hot mixtures of liquid and solid substances (slurries), which system comprises at least one displacement pump, preferably a membrane pump,-and at least one bidirectional flow pipe, connectable on one side, via a first one-way valve, to a supply pipe for drawing an amount of medium from said supply pipe, and which is connectable on the same side, via a second one-way valve, to a discharge pipe for discharging an identical amount of medium from said bidirectional flow pipe, whereby said bidirectional flow pipe is connected on its other side to a second pipe, which is circumnferentially provided with heat exchange means, which second pipe is connected with its other end to a pump chamber of the displacement pump.

A pump system of the above kind is disclosed in published Dutch patent application No. 9.0 01 678 in the name of the present applicant. Said known pump system is used for pumping a hot slurry from a supply pipe to a discharge pipe.

An amount of a hot mass is drawn into the bidirectional flow pipe by means of the displacement pump with every stroke, which amount of medium is forced from the bidirectional flow 25 pipe into the discharge pipe with the subsequent delivery stroke. The displacement volume of the displacement pump and the volume of the bidirectional flow pipe are thereby geared to each other in such a manner that the amount of medium drawn in and forced out fills the bidirectional flow pipe entirely or only partially. The bidirectional flow pipe is thereby connected to the pump chamber via a second pipe having a liquid column present therein. The movements of the pump element are thereby transmitted to the liquid mass in the bidirectional flow pipe by the liquid column in the *3S second pipe, whereby the hot medium in the bidirectional flow pipe is kept separated from the pump element by the liquid column present in the second pipe..In order to maintain the temperature at the location of the pump casing at an acceptable level, heat exchange elements are provided round the second pipe, which elements cool the medium column present in said pipe. With this known embodiment of such a* pump system the second pipe extends in vertical direction.

The advantage of this is that it enables a limited construction volume. A drawback of said vertical arrangement of said second cooled pipe is, however, that an enhanced heaE transport will occur in the direction of the displacement pump as a result of conduction and especially as a result of the occurrence of a convection current in said pipe. on the one hand this leads to a higher temperature at the pump casing, which is no longer acceptable under certain circumnstances, whilst on the other hand it also leads to greater heat Losses, because a larger amount of heat must be removed by cooling. With slurry temperatures in the order of 150 0 C these problems are still acceptable, but at higher temperatures of the medium to be pumped, as they will increasingly occur in the future, this leads to very large cooling capacities and a corresponding cooling water consumption so as to keep the temperature at the pump casing at an acceptable level. Furthermore this leads to large heat losses of the medium to be pumped, which is also disadvantageous from an energy point of view.

Another embodiment of a pump system as described before is known from EP-A-0048535. Also with this known pump system a vertical pipe is present between the bidirectional flow pipe and the pump device, which vertical pipe containsa medium column for transmitting the piston movements, whereby heat and mass transport in the direction of the pump device 30 will occur in this pipe again as a result of conduction and convection. As a result of this excessive temperatures will occur at the pump casing, especially with higher temperatures of the medium to be pumped, and a large amount of heat will have to be removed by cooling, which is disadvantageous from lo*o 35 an energy point of view.

From PCT/US79/00697 a system is furthermore known wherein the inlet and outlet valves and the bidirectional flow pipe are positioned higher than the displacement pump, as a result of which the direction of the convection current has a positive effect as regards the heat transport, but said systems are only suitable for non-settling l iquids, and certainly not for slurry suspensions, for which the present invention is in particular intended.

The object of the invention is to provide a pump system of the kind indicated above, wherein the aforesaid drawbacks are obviated and by means of which high-temperature media can be pumped without this leading to excessively high temperatures at the displacement pump and without having to remove an excessive amount of heat in the second pipe by cooling.

In order to accomplish said objective the pump system according to the invention is characterized in that a partition element is disposed in the bidirectional flow pipe, which partition element at least partially shuts of f the passage through said pipe. Said partition element impedes the transport of the hot and frequently corrosive medium in the direction of the pump casing and the membrane pump to a considerable degree. In this manner the load on the device as a whole is reduced, less heavy demands are made on the individual components and a simpler and cheaper construction of the device is made possible.

The partition element may be capable of free reciprocating movement in the direction of the axis of the pipe, and in particular be slidably mounted on a guide bar disposed in line with the central axis of the bidirectional flow pipe. This prevents unnecessary influencing of the pumping action.

According to the invention the partition element may be provided with a number of through channels, which function to prevent any unnecessary negative influencing of the pumping action. The transport of the medium in the direction of the pump casing and the membrane pump can also be impeded by configuring the partition element as a disc-shaped element having a diameter which is smaller than the diameter of the bidirectional flow pipe, or as an elongated element.

In addition to that the pump system according to the invention may be characterized in that the second pipe is provided at the locatiQn of the heat exchange means with means which have a mixing effect on the medium present at that location, such that the medium will be placed into proper heat exchanging contact with the pipe wall. This leads to an enhanced cooling effect of the heat exchange means on the hot medium.

According to another embodiment, in order to obtain a compact construction, the pump system according to the invention is characterized in that the pump is accommodated in the system in such a manner that the central axis of the pump extends substantially parallel to the central axis of the second pipe.

The invention will be explained in more detail hereafter with reference to the drawing, which shows a few embodiments of a pump system according to the invention.

Figure 1 shows a diagrammatic view, not to scale, of a pump system according to the invention.

Figures 2a and 2b are detailed views of other embodiments for use in the pump system according to the invention.

Figure 1 shows a pump system comprising a supply pipe 2 and a discharge pipe 3. The pump system furthermore comprises a displacement pump 4 (partially shown) for drawing in a medium 5, for example a slurry, from supply pipe 2, via a first one-way valve 6, into a generally horizontally disposed bidirectional flow pipe 7, 50. Said drawing in of o. medium 5 takes place in a suction phase, which is followed by a delivery phase, in which the medium 5, which has collected in bidirectional flow pipe 7, 50, is forced into a discharge pipe 3 connected thereto via a second one-way valve 8. The two one-way valves 6 and 8 used in the illustrated embodiment are ball valves. It is also possible, however, to use other S types of one-way valves, such as conical valves, ring valves 35 or flat valves. Valve 6 is open and valve 8 is closed during the suction phase, whilst valve 6 is closed and valve 8 is open during the delivery phase.

On its side remote from the valves bidirectional flow pipe 7, 50 is connected to a horizontally extending pipe which is surrounded by a heat exchanger 11, through which a cooling medium is passed from inlet 12 to outlet 12.

on its side remote from said bidirectional flow pipe second pipe 10 is connected, via a bent pipe 13, to the pump chamber 14 of a membrane pump 4. Membrane pump 4 possesses a membrane 15 disposed in a pump casing 16 to which pipe 13 is connected. The membrane pump is provided with a piston rod 17, which is reciprocated by driving means (not shown).

Attached to piston rod 17 is a displacement member 17, which is capable of movement within a cylinder 19. Piston rod 17 may reciprocate membrane 15 directly, if desired, but said reciprocation may also be effected via an intermediate medium shown in the figure, which is reciprocated by displacement member 18 and which transmits said reciprocating movement to membrane 15. The reciprocating movement of membrane results in the suction phase and the delivery phase, as a result of which medium 5 is transported from supply pipe 2 to discharge pipe 3.

In the embodiment shown in Figure 1 the displacement pump is a membrane pump, which may either be a single-acting pump or a double.-acting pump, in which latter case an intermediate medium will be present to the right of displacement member 18, which intermediate medium is capable of moving a membrane (not shown) and operating another pump system. Instead of using a membrane pump it is also possible to use ordinary displacement pumps, and the pump system may comprise several such displacement pumps.

As is shown in Figure 1, the displacement pump is disposed in the illustrated pump system in such a manner that the central axes of the rods extend parallel to second pipe This has resulted in a highly compact construction of the pump system.

Bidirectional flow pipe 7 of the pump system is provided 35 with an intermediate pipe'50, which is connected to bidirectional flow pipe 7 by means of a flange 51b, and which is connected to supply and discharge pipes 2 and 3 by means of a flange Sla. Intermediate pipe 50 normally forms part of bidirectional flow pipe 7, in which medium 5 collects, The embodiment of the pump system as shown is according to the invention characterized in that a partition element 52 is present in the intermediate pipe (also called bidirectional flow pipe). Said partition element 52 can freely reciprocate in the direction of the axis of intermediate pipe 50. T o this end partition element 52 is provided with guides 54, and it is slidably mounted on a guide bar 53 extending along the central axis of intermediate pipe 50. Said guide bar 53 is connected to intermediate pipe SO near flanges Sla and Sib, in a manner which is known, but which is not shown.

The freely movable partition element 52 forms a more or less physical partition in bidirectional flow pipe 7, 50, and impedes to a considerable extent transport of the hot and frequently corrosive medium 5 in the direction of pump casing 16. It has become apparent that the hot medium 5 moves slowly in the direction of pump casing 15 as a result of the periodic suction and delivery phases of membrane 15- Thus the placing of partition element 52 provides additional protection of the pump casing and membrane 15, whilst it furthermore prevents unnecessary loading of heat exchanger This arrangement makes it possible to lower the req-uirements that are made of heat exchanger 11, thus enabling a simpler and cheaper constr'uction thereof.

Furthermore pump casing 16 and in particular membrane 15 will be loaded to a much smaller extent by the hot medium 5, as a result of which the life of these components is considerably prolonged. Consequently the requirements made of the construction may be lowered as well, which enables a cheaper 00 overall installation.

Another aspect of the invention is indicated at Numeral 55 indicates mixing means, which are placed in pipe 10 at the location of heat exchanger i1. In this embodiment O 35 said mixing means 55 consist of a large number of blades 56, which are mounted on a shaft 57 extending along the central axis of pipe 10. Alternatively the blades may be mounted on the inner wall of pipe 10. Said mixing means have a mixing effect on medium 5, such that medium 5 are placed into proper heat-exchanging contact with the wall of pipe 10 of heat exchanger 11. Said mixing action of the mixing means consists primarily of increasing the flow turbulence of medium 5 in pipe 10, which functions to increase the contact between heat exchanger 11 and the hot medium and thus obtain a greater cooling effect on hot medium 5. In particular if medium exhibits a flow behaviour with predominantly low flow velocities, the static mixing means will increase the turbulence of the hot medium considerably, thus increasing the cooling effect which heat exchanger 11 has on the medium.

Figures 2a and 2b show two embodiments of the partition element according to the invention. The two figures show intermediate pipe 50, which can be fitted into bidirectional flow pipe 7 of Figure 1 by means of flanges 51a and 51b.

Analogously to Figure 1, Figure 2a shows a guide bare 53, which is disposed along the central axis of intermediate pipe and which is fixedly connected at its ends 60a and to flanges 51a and 51b respectively in a manner which is known per se. A partition element 52 provided with suitable guide means 54 is mounted over said guide bar in a manner which allows free reciprocating movement. Partition element 52 at least partially shuts off the passage through intermediate pipe 50. In the embodiment shown in Figure 2a partition element 52 is configured as a disc-shaped element having a diameter which is smaller than the diameter of pipe Said disc-shaped element is preferably made of a a flexible, heat and corrosion resistant rubber material, so as not to affect the pumping action of the membrane pump, in particular when the pump system is being started.

Alternatively more than one disc-shaped elements can be mounted on said guide bar 53 or the diameter of the discshaped element can be larger than-the diameter of pipe which disc-diameter will be reduced due to the friction with the inner wall of the intermediate pipe S0 during operation of the pump system.

Figure 2b shows another embodiment of the partition element according to the invention. Analogously to Figure 2a, a guide bar 53 is mounted along the central axis of intermediate pipe 50, which guide bar is fixedly connected at its ends 60a and gob to flanges 51a and Sib respectively in a manner which is known per se. Partition element 61 of this embodiment is elongated, however, and it is built up of a number of through channels 62, which are arranged in a row round guide bar 53. This is shown in section A-A of Figure 2b. Unlike the embodiment shown in Figure 2a, the partition element 61 of this embodiment is not capable of free reciprocating movement, but it is fixedly mounted on guide bar 53_ The presence of channels 62 allows hot medium to pass in the direction of heat exchanger 11 and pump casing 16. During the suction phase of the membrane pumfp the medium flowing in will exhibit a turbulent flow behaviour, which turbulence is converted into a laminar flow by channels 62. As a result of this the convection of heat in the direction of heat exchanger 11 and pump casing 16 (and membrane 15) will decrease considerably, and the constructional demands to be made of heat exchanger 11 and pump casing 16 may be lowered.

This makes it possible to achieve a simpler and cheaper construction.

It will be apparent that also the disc-shaped element 52 shown in Figure 2a may be provided with a number of through channels- The partition element may be configured in the form of a sphere, which is provided in pipe SO in a manner which allows free reciprocating movement. Also a brush-shaped element provided with a large number of protrusions will be satisfactory,

Claims (2)

1. A pump system in part icular suitable for pumping hot media, such as hot mixtures of liquid and solid substances (slurries), which system comprises at least one displacement pump, preferably a membrane pump, and at least one bidirectional flow pipe, connectable on one side, via a first one-way valve, to a supply pipe for drawing an amount of medium from said supply pipe, and which is connectable on the same side, via a second one-way valve, to a discharge pipe for discharging an identical amount of medium from said bidirectional flow pipe, whereby said bidirectional flow pipe is connected on its other side to a second pipe, which is circumferentially provided with heat exchange means, which second pipe is connected with its other end to a pump chamber of the displacement pump, characterized in that a partition element is disposed in the bidirectional flow pipe, which partition element at least partially shuts off the passage through said pipe, thereby limiting the transfer of heat from the hot medium at one side of the partition element to the other side thereof.

992. A pump system according to claim 1, characterized in that said partition element is capable of free *see. reciprocating movement in the direction of the axis of the pipe. 9 A pump system according to claim 2, characterized in that said partition element is slidably mounted on a guide bar disposed in line with the central axis of the bidirectional flow pipe. 4. A pump system according to any one of the claims 1 characterized in that said partition element is provided with a number of through channels. A pump system according to any one of the claims 1 09 4, characterized in that the partition element is a disc- shaped element having a diameter which is smaller than the diameter of the bidirectional flow pipe. 6. A pump system according to any one of the claims 1 4, characterized in that said partition element is an elongated element. 7. A pump system according to any one of the preceding claims, characterized in that mixing means are present in the second pipe near the heat exchanging mneans- 8. A pump system according to claim 7, characterized in that said mnixing means consist of a large number of blades, which are mounted on a shaft extending along the central axis of the second pipe. 9. A pump system according to claim 7 or 8, characterized in that said mixing means consist of a large number of blades mounted on the inner wall of the second pipe. A pump system according to any one of the preceding claims, characterized in that the pump is accommodated in the system in such a manner that the central axis of the pump extends substantially parallel to the central axis of the second pipe. Dated this 22nd day of February 2001 ENVIROTECH PUMPSYSTEMS NETHERLANDS B .V By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia Gee* a 0