Gas separation: processes – With control responsive to sensed condition – Pressure sensed
Patent
1991-12-19
1993-08-10
Nozick, Bernard
Gas separation: processes
With control responsive to sensed condition
Pressure sensed
55352, 95273, B01D 4600
Patent
active
052344819
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates to a filtration and pressure stabilization device for a variable-flow ventilation system.
It is known that ventilation systems can be made to have a variable flow, either to provide heat loads with a variable value, or to modify the flow as a function of the needs of the premises to be ventilated. It is also known, particularly in office buildings or industrial buildings, that forced-air ventilation can be provided, allowing the flow to be controlled in each room. It is advantageous to have a filter ahead of the fan, which can purify the air blown into the various rooms.
It should be noted that the filter introduces variations in the value of the pressure available hence variations in the value of the flow, which affects the desired flow.
A first solution in maintaining the desired flow consists of regularly cleaning the filters. However, this cleaning is an expensive maintenance operation and does not fully stabilize the pressure, since even if the filter is replaced before it is completely clogged, the value of the pressure available will vary depending on how much dirt the filter has accumulated.
There are also roll-type filters, namely filters with a greater length than the length of the air inlet opening with which the filter is associated, this roll-type filter cooperating with a supply roller and a takeup roller which are driven synchronously at regular time intervals.
Other than the fact that the roll-type filter does not ensure full pressure stabilization, it requires frequent replacement to prevent clogging which results in a high operating cost.
German Patent DE-A-2,338,048 relates to a device having a roll-type filter with which a variable-position shutter is associated. The goal of this device is to neutralize a useful part of the filter when the ventilation flow decreases. Thus, the idea is automatically to adjust the filter surface area to variations in flow, without taking into account the dirtiness of this filter surface. Thus, when the flow is far from the maximum capacity of the filtration device, and the exposed filter surface offers too much air resistance because it is dirty, the filter is replaced instead of exposing a larger filter surface. Thus, this control method affords no filter economies whatever.
SUMMARY OF THE INVENTION
The goal of the invention is to furnish a device able to stabilize pressure, taking into account both the air flow and the filter dirtiness with a view to benefiting from totally regular pressure conditions, while using each filter to the maximum of its capacity, i.e. allowing it to be clogged completely, which saves on filter material costs.
For this purpose, the device according to the invention is associated with an air inlet opening in a fan housing and to a traveling filter equipped with means allowing the useful part of the filter located opposite the air passage opening to be renewed, and a shutter element, made of impermeable material, designed to be applied against the filter and cover it wholly or partially. The shutter associated with means for controlling its movement. The movement control means is connected to a computer which receives information from a sensor located in the fluid stream and is characterized by the sensor measuring the fluid pressure or flow at the outlet of the fan housing. The computer is designed such that pressure stabilization is effected first by changing the position of the shutter then, when the shutter is in the "filter fully exposed" position, by acting on its control means to renew the filter, at least partially.
In practice, when the filter is new and the flow is weak, the shutter covers most of the filter. When the filter is dirty or when the flow increases, the shutter exposes a larger filter surface area to keep the pressure constant. As the filter becomes dirtier, more and more of it is uncovered by the shutter. When the filter is totally uncovered by the shutter, and the pressure value is less than the setpoint, the computer causes part of the filter to be replaced. T
REFERENCES:
patent: 3332215 (1967-07-01), Revell
patent: 3985528 (1976-10-01), Revell
Jardinier Pierre C. J.
Simonnot Jacques
Nozick Bernard
Societe d'Etude et de Recherche en Ventilation et Aeraulique Ser
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