Pumps – Motor driven – Fluid motor
Reexamination Certificate
1999-01-19
2001-02-06
Thorpe, Timothy S. (Department: 3746)
Pumps
Motor driven
Fluid motor
C417S900000, C417S279000
Reexamination Certificate
active
06183216
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is related to an arrangement for long-distance conveying of thick matter, in particular liquid concrete, comprising a thick matter pump and a thick matter distributor which is adapted to be coupled to a pressure joint of the thick matter pump by way of a high pressure feed line.
DESCRIPTION OF THE RELATED ART
In the conveying of thick matter over great distances, tight limits are set in dependency on the viscosity of the thick matter and its friction with the wall of the high pressure feed line. In order to increase the attainable conveying distance, it has been proposed (EP-B 0 633 863) to reduce the friction by injecting a lubricant into the region between the wall of the feed line and a length of thick matter formed in and transported along the feed line. This method may be applied especially when conveying thick matter containing a high fraction of solids and when conveying distances of some hundred meters are to be attained. With thick matter containing a high liquid fraction, such as liquid concrete, it is sought to achieve conveying distances of some thousand meters, for instance in tunnel construction work, which cannot be achieved with the known lubricant injection.
SUMMARY OF THE INVENTION
Based on this, it is the object of the invention to develop an arrangement of the type described above for long-distance conveying of thick matter, in particular of liquid concrete, which makes it possible to significantly increase the attainable conveying distance for a given pumping capacity.
The solution according to the invention is based foremost on the idea to reduce the pressure decline along the high pressure feed line by charging only a fraction of the total length of the high pressure feed line with the thick matter to be conveyed, while the remaining length, which may be longer than the charged length, is charged with a pressure medium having a low viscosity and little friction with respect to the feed line wall. In order to achieve this it is proposed according to the invention that the high pressure feed line is connected to a pipe-switching device on the pump side as well as on the distributor side, each of which pipe switching devices is adapted to be alternatingly switched to two connections, wherein the pipe switching device on the pump side is connected to the pressure joint of the thick matter pump with its one connection, and at its other connection to the pressure joint of a thick matter pump which is adapted to be charged with a low-viscosity pressure medium by way of a reservoir, wherein the pipe-switching device at the distributor side is connected at its one connection to the thick matter distributor and at its other connection to the reservoir of the pressure medium pump by way of a return feed line, and wherein the pipe-switching device on the distributor side is adapted to be switched in response to a material change from thick matter to pressure medium or from pressure medium to thick matter occurring in the incoming material flow. Expediently, a sensor which responds to a material change in the material flow and activates the switching operation of the pipe-switching device on the distributor side is provided therefore.
During the steady-state operation of the conveying arrangement it is of advantage when the pipe-switching device on the pump side is adapted to be switched as a function of, preferably synchronous to, the pipe-switching device on the distributor side. In this case it is achieved that always the same amount of thick matter and the same amount of pressure medium are present along the length of the conveying distance and that an approximately constant pressure decline occurrs for a given consistency of the thick matter.
In order to avoid a mixing of the thick matter to be conveyed and the pressure medium in the region of the separation point and to be able to better sense an occurrance of material change, it is proposed according to a preferred embodiment of the invention that a pig trap is connected to the high pressure feed line in the region of the pipe switching device on the pump side, by way of which pig trap at least one partitioning member which is adapted to the cross section of the high pressure feed line is introduced into the high pressure feed line at each switching of the pipe switching device on the pump side. On the other hand the high pressure feed line in the region of the pipe switching device on the distributor side or the return feed line in the region of the reservoir may comprise a pig trap for extracting the incoming partitioning members. In order to be able to switch the the pipe switching device on the distributor side always at the correct instance, it is of advantage when a sensor which responds to an arriving partitioning member and which initiates the switching operation is disposed in the region of the corresponding pipe switching device. The sensor is for example designed to be a magnetic or ultrasonic sensor which responds to the presence of a partitioning member in the high pressure feed line.
Especially during the start-up phase and while conveying thick matter of varying consistency it has proven to be of advantage to provide a sensor for initiating the switching of the pipe switching device on the pump side, which sensor responds to a defined feed pressure of the thick matter pump or a defined pressure decline in the high pressure feed line. With such a measure it is possible to operate the conveying arrangement, for a given conveying capacity, always at an optimum thick matter conveying amount. In order to avoid operating failures, it is important that a backflow prevention device is disposed in the feed line leading from the pressure medium pump to the pipe switching device on the pump side.
The long-distance conveying arrangement according to the invention is expediently used in tunnel construction work. In this case the thick matter distributor may be desigend to be a tunnel shuttering distributor.
In the instance of liquid concrete being the thick matter to be conveyed, water or a concrete-water-mixture or a low-viscosity liquid polymer is used as a pressure medium.
REFERENCES:
patent: 2953158 (1960-09-01), Shea et al.
patent: 3938912 (1976-02-01), Sakamoto et al.
patent: 4371294 (1983-02-01), Sakamoto
patent: 4714888 (1987-12-01), French et al.
patent: 5318408 (1994-06-01), Davidsson
patent: 5522264 (1996-06-01), Smith et al.
Pendorf & Cutliff
Putzmeister AG
Solak Timothy P
Thorpe Timothy S.
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