Conveyors: fluid current – Processes
Reexamination Certificate
1998-11-20
2001-09-11
Ellis, Christopher P. (Department: 3651)
Conveyors: fluid current
Processes
C406S014000, C406S030000, C406S085000, C406S127000, C406S146000
Reexamination Certificate
active
06287056
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the field of conveying technology. It relates to a method for operating a pulse flow conveying installation which is intended for the conveying of a solid material, present in the form of bulk material, by means of a conveying gas, in the case of which pulse flow conveying installation an alternating sequence of solid material pulses and conveying gas pulses is generated by first means in the conveying conduit and pressed through the conveying conduit.
The invention further relates to a pulse flow conveying installation for carrying out the method, comprising a device, connected to the inlet of a conveying conduit, for introducing the solid material into the conveying conduit, which introduction device can be filled with the solid material to be conveyed and introduces it in controlled fashion into the conveying conduit, and further comprising a pulsator which is connected to the conveying conduit downstream of the introduction device in the direction of conveying and by means of which the conveying conduit can be acted upon, via a first controllable valve, by a pressurized conveying gas.
Such a method and such an installation are known, for example, from the brochure No. 573/2 of the applicant.
PRIOR ART
In known pulse flow conveying installations (pulse flow conveying systems), pulverulent or granular bulk materials are fed through pipes to a destination location by means of compressed air (or another pressurized conveying gas). In this case, by means of pulses induced by air injection, the solid materials are conveyed in pulse form through the pipe. A solid material pulse is followed by an air pulse, and vice versa. As a result of the air injection, the conveying pressure is reduced and the conveying capacity is set.
Now in practice—as a result of alterations in the pulse movement in relatively long pipes—it is possible for conveying conditions to occur which, with unaltered injection conditions, give rise to a slight increase in the conveying pressure or a large pressure increase with choking. In the event of the occurrence of such choking, the conveying process is interrupted and it is necessary for the choking to be eliminated. This leads to an undesired interruption in operation and additional maintenance expenditure.
SUMMARY OF THE INVENTION
It is accordingly the object of the invention to specify a method of operating a pulse flow conveying installation, in which method the danger of choking is recognized in due time and the pressure increases in the conveying conduit which lead to choking are automatically eliminated.
In the case of a method of the initially mentioned type, the object is achieved in that the conveying pressure is regulated, and in that, to regulate the conveying pressure in the conveying conduit the instantaneous volume flow of the conveying gas flowing through the conveying conduit is altered in relation to the instantaneous volume flow of the solid material conveyed on a time average basis through the conveying conduit. As a result of the regulation, according to the invention, of the conveying pressure, a permanent increase in the conveying pressure and a concomitant choking are automatically prevented. If a pressure increase is detected, the operational parameters of the installation are altered to the end that the pressure increase is eliminated and the conveying pressure is restored to its normal value. In this case, to perform the regulation use is made of the finding that the pressure loss in the conveying conduit is, in characteristic fashion, dependent on the matter of what is the ratio of the volume flow of the conveying gas flowing through the conveying conduit to the volume flow of the solid material conveyed through the conveying conduit. If the volume flow ratio is increased, the pressure loss or the conveying pressure falls. In contrast, if the volume flow ratio is reduced, the pressure loss increases.
A first preferred embodiment of the method according to the invention is distinguished in that to alter the quantity of conveying gas the length of the generated solid material pulses and/or conveying gas pulses in the conveying conduit is altered, in that for the generation of a solid material pulse solid material is pressed into the conveying conduit from a sender filled with solid material by means of conveying gas in a first temporal cycle, in that for the generation of a conveying gas pulse conveying gas is pressed into the conveying conduit via a pulsator in a second temporal cycle, and in that to alter the conveying pressure in the conveying conduit the ratio of the first temporal cycle to the second temporal cycle is altered. This results in a particularly simple and effective regulation of the conveying pressure.
A second preferred embodiment of the invention is characterized in that the conveying pressure in the conveying conduit is progressively measured, in that the measured value of the conveying pressure is compared with a predetermined theoretical value, and in that the ratio of the first temporal cycle to the second temporal cycle is reduced if the measured value is greater, beyond a predetermined first limiting value, than the theoretical value, and in that the ratio of the first temporal cycle to the second temporal cycle is increased if the measured value is smaller, beyond a predetermined second limiting value, than the theoretical value.
In practice, it has proved to be effective in this case if, according to a preferred further development of this embodiment, the predetermined theoretical value is selected in such a way that in disturbance-free normal operation the achieved conveying pressure corresponds to the theoretical value within the predetermined limiting values with a ratio of the first temporal cycle to the second temporal cycle of approximately 1, and that, on exceeding the first limiting value, the temporal cycle ratio is reduced to a value smaller than 1, until the conveying pressure again undershoots the first limiting value, and that, on undershooting the second limiting value, the temporal cycle ratio is increased to a value greater than 1, until the conveying pressure again exceeds the second limiting value.
The pulse flow conveying installation, according to the invention, of the initially mentioned type is characterized in that at least one pressure pickup to measure the conveying pressure in the conveying conduit is disposed at the conveying conduit, and in that, to drive the introduction device and the first valve, a control device is present, which is operatively connected to the pressure pickup and alternately drives the introduction device and the first valve as a function of the measured conveying pressure.
A preferred embodiment of the installation is distinguished in that a comparator is disposed between the at least one pressure pickup and the control device, and in that the regulating unit is designed in such a way that it drives the introduction device and the first valve with temporal cycle ratios which can be switched over.
Further embodiments are evident from the dependent claims.
REFERENCES:
patent: 3604758 (1971-09-01), Flain
patent: 4545410 (1985-10-01), Paul et al.
patent: 4775267 (1988-10-01), Yamamoto
patent: 6085939 (2000-07-01), Geweke et al.
Dillon, Jr. Joe
Ellis Christopher P.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Gericke AG
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