Fluid handling – Line condition change responsive valves – Direct response valves
Patent
1997-04-17
1999-11-16
Ferensic, Denise L.
Fluid handling
Line condition change responsive valves
Direct response valves
454259, 137 1, F16K 1500
Patent
active
059839309
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a throttle device for delivery of a current of gas through a channel, the device comprising a flap which is arranged so that it can pivot on an axle and which is designed in such a way that, at a certain pressure force exerted by the current of gas, it is opened from a position in which the channel is essentially closed.
PRIOR ART
In connection with boilers of various types, for example recovery boilers for use in the production of paper pulp, or heating boilers or steam boilers for solid fuels, such as, for example, bark, peat or coal, it is of great importance that the combustion take place with a uniform and controlled delivery of air and with sustained air penetration, even at partial loads. This leads to an optimized combustion, which results in a high degree of efficiency of the boiler and in a low proportion of environmentally hazardous discharge from the said boiler.
In connection with the delivery of air to boilers, air nozzles of various types are normally used, which air nozzles can consist of flaps which are opened by the pressure force exerted by the current of air. A throttle device for a heating boiler is already known from the document EP 0,022,599, which throttle device comprises a valve flap whose degree of opening can be set with the aid of an adjustable stop screw. This prevents draught from occurring when air is not flowing into the heating boiler. A throttle device for a heating boiler is also already known from FR 1,033,033, which throttle device comprises adjusting members for setting the degree of closure of a pivotably mounted valve flap.
However, a disadvantage of these and other previously disclosed devices is that they do not permit a high penetration of air, that is to say a high degree of penetration of the air upon reduction of the air flow through the nozzle, without a considerable increase in the pressure for this penetration. Good penetration of air is necessary in order to achieve an optimized combustion in the boiler, while at the same time an increased pressure requirement for the combustion air increases the energy consumption in the plant.
DISCLOSURE OF THE INVENTION
A principal object of the present invention is therefore to solve the abovementioned problems and to provide a throttle device with improved air penetration, that is to say with an increased degree of penetration of air which is flowing into the boiler, at the same time as the necessary pressure change for the combustion air is minimized. This is achieved by means of a device of the type mentioned in the introduction, which device is characterized in that it comprises at least one weight which is arranged to rotate together with the flap and is designed to deliver a torque to the axle in conjunction with the pivoting of the flap.
By using such a weight which is arranged on the axle and which assists, on the one hand, in opening the flap, and, on the other hand, in counterbalancing the gravity of the flap when a certain air pressure is present in the channel and the flap is open, an increased and virtually constant velocity of the inflowing air is achieved, and this leads to an improved function and reduced energy consumption of the boiler. In addition, the invention affords the possibility of opening different air nozzles at different air pressures in order to alter the flow pattern in the boiler without recourse to a complicated control system.
DESCRIPTION OF THE FIGURES
The invention will be described in greater detail hereinbelow with reference to the attached figures, of which:
FIG. 1 is a side view of the device according to the present invention,
FIG. 2 is a perspective view of an alternative embodiment of the invention, and
FIG. 3 is a diagrammatic view of another embodiment of the invention.
PREFERRED EMBODIMENTS
FIG. 1 shows a throttle device in the form of an air nozzle in accordance with the present invention, which device is arranged in a channel 1 for delivery of air to an inlet 2 of a furnace. The furnace is part of a boiler whic
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Farid Ramyar
Ferensic Denise L.
Kvaerner Pulping AB
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