GB2304878A - Forced draft controlling device for gas-oil heaters - Google Patents

Description

2304878 FORCED DRAUGHT GAS-OIL HEATER CONTROL DEVICE

DESCRIPTION

FIELD OF APPLICATION

Forced draught gas-oil heaters are used to individually heat residential premises, including apartment buildings.

OBJECT OF THE INVENTION The invention hereby advanced consists of a forced draught gas-oil heater control system, characterized by connecting the burner to the outlet of an electronically controlled, a all or nothing" electrically operated valve, located between the burner and the device regulating the fuel flowing from the deposit, as well as an electronic system fitted with power stage and used to control both combustion and a centrifugal extractor fitted with infrared speed reader, with extractor velocity tachometer indicator and a start-stop push button.

A micro-computer receives the functional signal from the electrically actuated valve, actuates the indicator and compares actual speed with that required, acting upon the extractor motor voltage regulator, through a conventional PID digital regulator.

BACKGROUND OF THE INVENTION

Gas-oil heaters may be split in two main groups, those corresponding to the injection and gravity types.

The former have their more extended application in industrial installations, heating up industrial premises, warehouses, etc., competing with liquid fuel nozzles and gas boilers.

Their functional characteristics is very similar in all of these cases, in so far as, in one way or another, there is a fuel drive, prior to combustion, effected through the action of mechanical or pressure means, adequate to said effects or even through prior compression, in the case of gas fuel, which expansion is then used for the draught.

This is not the case of gravity gas-oil combustion heaters: In these heaters the fuel comes, generally, from a deposit placed laterally and internally to the heater and in an arrangement slightly higher than a fuel feed regulator, conventional and of the level type that has to incorporate at least an admission valve, a normal float fitted tank, closing fuel passage, plus a filtering unit to filter out fuel impurities, a discharge dosing valve and a flow indicating device.

This regulator discharges, through its lower portion, to a gravity feed conduit leading to the burner admission inlet, arranged below and so that the fuel arriving from the side deposit tends to look for its own level, through communicating pipes, thus feeding the combustion outlet.

This specific arrangement and the absence of air feeding or extracting fans, arranged prior to the burner, which would cause a considerable number of combustion problems, would cause that the only forced draught would be the extraordinarily minor one caused by the flues, as a function of their diameter, which yield a low velocity resultant to residual gases, so small that flue draught may even totally stop whenever there is a major temperature difference, besides the logical condensations.

3 1 on the other hand, conventional burners do not maintain the permanent blue flame, evidence of a perfect combustion, but it does instead acquire reddish tones and, may sometimes even be totally red generating a large quantity of residues and, above everything else, giving off foul smelling partially unburnt gases, which control would require the user to effect a continuous and uninterrupted follow up.

It is precisely these gravity feed and proper combustion 10 process continuity deficiency reasons which, up to date, have prevented the installation of gas-oil heaters with draught oriented towards vertical construction elements.

The applicant has a new burner design, producing permanent 15 blue quality flame, object of another different registration and is not aware of the existence of forced draught control means acting in a nearly instantaneous manner upon the combustion of this kind of gravity heaters and that would allow them to have a very small diameter smoke outlet oriented towards vertical construction elements, without the air roughing affecting combustion.

DESCRIPTION OF THE INVENTIO

The invention object of this specification refers to a new draught control system, generally for gas-oil combustion heater smoke extraction conduits and, more specifically, for those heaters used to heat up residential premises.

These heaters make use of a new burner design, of high combustion performance and high purity in the production of gas residues, thus enabling a different smoke extraction arrangement.

The invention consists of a powered regulation system, using a closed chain, to stabilize the draught of a horizontal inlet conduit to an external wall of the building or residential premises to be heated, of a very small diameter, of approximately one fifth of that available in conventional outlets, as normally effected through the ceiling of free standing houses and, in the case of apartment blocks, through the various ceiling-floor surfaces all the way up to the roof.

This powered system incorporates a heater fuel feed control device made up of an electronically controlled "all or nothing" valve fitted between the combustion flow regulator and the burner itself.

It is further fitted with an electronic control system, with air impulsion means, consisting of a centrifugal extractor and a device that reads its speed using infrared beams, the assembly being then completed through the addition of a metering device and general connecting cabling.

The centrifugal extractor, of variable speed and with a wide range of operating speed grading in respect of its optimum design operating speed, maintaining a previously fixed and uniform draught, consisting of a tangential air passage type wheel, is built in a floating manner so as to reduce its noise level down to values admissible for its indoor night time use.

The motor of this fan is connected to the electronic control system, as well as the infrared speed reader, acting as a multiple perforation wheel tachometer with aninfrared transmitter-receiver that transforms the passage of the perforations and converts them into impulses, so as to regulate the speed of the motor driven fan.

The electronic control system does also command an 'all or nothing" needle type electrically actuated valve that interrupts gas-oil supply in cases of insufficient or non existent transient draught conditions such as, for instance, an obstruction triggering an alarm, as well as due to other normal causes such as lack of electric power supply, incorrect connections, etc., so that acting upon the fan and upon the cut-off valve would enable the proper operation of the heater in this forced draught arrangement with outlet to small vertical wall orifices.

DRAWING DESCRIPTION

In order to complement the description herein effected and 15 so as to enable the better and easier comprehension of the characteristics of the invention, this patent specification includes, as integral part thereof, a set of drawings where, for illustrative and not limitative reasons the following has been duly represented:

Figure 1 shows a schematic side elevation cut away view of the heater attached to an outdoors wall, duly showing some of the improvements of this invention.

Figure 2 is a front elevation view, also cut away, of the fore mentioned heater.

PREFERRED EXECUTION OF THE INVENTION upon inspecting the fore mentioned figures, it may be observed that the invention herein advanced consists of a gas-oil heater forced draught control device, to heat residential premises, of the optimized combustion burner (1) type with a high degree of purity in the production of gas residues, configured as a power driven system (5) regulated by closed chain, through a conventional proportional, integral and derivative (PID) digital regulator, to stabilize combustion gases exhaust draught, using a 80 mm diameter conduit, as well as fuel control using an all or nothing" electrically actuated valve (2) fitted between the burner (1) and a conventional constant level float controlled regulator (3), fed by fuel from the tank (4), as well as a power stage of a centrifugal extraction unit (6) with infrared speed reader (7), the assembly being then completed by a tachometer indicator (8) that indicates extractor speed to the user (6), being further fitted with a start-stop push button, a microcomputer that receives the functional signal from the electrically driven valve, that actuates the indicator (8) and that compares the speed shown with the previously set one, acting upon the extractor motor voltage regulator (6) and finally also fitted with its corresponding general electrical cabling.

The centrifugal extractor (6) is made up of a floating wheel 20 with variable speed between 400 and 2400 rpm through voltage regulation, maintaining an operating speed of about 1000 rpm and being designed to withstand high temperatures and with the motor connected to the electronic system (5), as well as reaching draught speed in about 3 seconds and coming up to operating speed in about 10 seconds.

The infrared reader (7), multi-perforated wheel tachometer with infrared transmitter-receiver transforms the passage of the perforations using an adaptor circuit and converts them into impulses, before their transmittal to the microcomputer, so as to regulate the speed of the motor driven fan.

The electronic control system (5) does also control the n all or nothing" electrically operated needle type valve (2) that starts up upon reaching 85% of operating speed and then interrupts gas- oil supply after 15 seconds of continuous failure, because of insufficient or non-existent draught, triggering an alarm condition, as well as due to lack of electric power, incorrect connections, etc., with automatic reconnection before 17 seconds or with a new alarm if air roughing or any other cause does still prevent its operation, deducting an equivalent time to the heater to use up any residual fuel from the electrically actuated valve (2).

It is not necessary to keep the forced draught pipe (9) heated so as to prevent condensation and draught pressure losses, which enables its cooperation in the transmission of radiation energy to the surrounding living area, up to its connection to the extractor (6), which outlet is connected to a small orifice (10) in the vertical wall (11).

This description is not extended any further in the understanding that any expert in this subject would have sufficient information to understand the scope of the invention and the advantages derived therefrom, as well as to be able to reproduce it.

Alternatively to the infrared transmitter - receiver speed variation control, other conventional systems producing a similar effect may also be incorporated or the measuring criteria may also be modified, for instance, to measure minimal differential pressures but still sufficient to enable the slightest depression caused by obstructions, air roughing, etc., to activate the gas extraction control.

It is amply understood that, if the essential features of the invention are not altered, both the variations in materials as the shape, size and arrangements of the elements may be varied within the same basic characteristics.

The terms used during the description and the sense of the latter must always be considered in a non limitative manner.

Claims (3)

1 - Forced draught controlling device for gas-oil heaters of the gravity fed type to be used to heat residential premises, fitted with an optimized burner (1) with a high degree of purity in the production of gas residues, essentially characterized by its being conf igured as a closed chain power driven regulation system (5), using a conventional proportional, integral and derivative (PID) digital regulator, to stabilize the combustion gases exhaust draught using a 80 mm diameter conduit, as well as to control fuel flow using an "all or nothing" electrical actuation valve (2) fitted between the burner (1) and a conventional constant level float type regulator (3), fed by fuel from the tank (4), as well as a power stage of a centrifugal extractor (6) with infrared speed reader (7), the assembly being then completed by a tachometer indicator (8) to keep the user informed about extractor speed, being further fitted with a start-stop push button, a micro-computer that receives the functional signal of the electrically actuated valve, acting upon the indicator (8) and comparing the speed shown against that previously set, acting upon the extractor motor voltage regulator (6) and, finally, fitted with general connecting cabling as required.

2. Gas-oil heater forced draught control, as per the prior claim, characterized because the centrifugal extractor (6), featuring fast response both to establish draught and normal operating speed, is fitted with a floating wheel allowing a wide speed regulation range from normal operating speed, properly designed to withstand the temperatures of said extraction and connection of its motor to the power drive mechanism (5), as well as its inlet connection to the forced draught pipe (9), being its outlet connected with a small orifice (10) in the vertical wall (11).

3. A gas-oil heater system as claimed in claim 1 or 2, in which the electricallyoperated valve is opened when the rotor nears its intended operating speed; in which the valve is closed, to interrupt the gas-oil supply, when the rotor speed fails below a threshold value, with the generation of a primary alarm, with automatic reclosure of the valve after an interval close to half the combustion time of the residual fuel left between the burner and the electrically-actuated valve, followed by a generation of a secondary alarm should air turbulence or any other cause still prevent operation of the exhaust extractor.

3. Gas-oil heater forced draught control, as per the foregoing claims, characterized because the infrared reader (7), multi-perforated wheel with infrared transmitterreceiver, transforms the passage of the perforations through an adaptor circuit converting them into impulses before sending them to the micro-processor of the power actuated mechanism (5) to regulate the speed of the motor driven fan.

4. Gas-oil heater forced draught control, as per the foregoing claims, characterized because the power drive mechanism (5) does also control the electrically operated valve (2) that starts up near the operating speed of the extractor (6) and that interrupts gas-oil supply instantaneously due to insufficient or non-existent draught, triggering an alarm, as well as due to the lack of electrical power, incorrect connection, etc., with automatic reconnection close to half the combustion time of the residual fuel left between the burner (1) and the electrically actuated valve (2) followed by a new alarm should air roughing or any other cause still prevent its normal operation.

5. Gas-oil heater forced draught control, as per the foregoing claims, characterized because as an alternative to the infrared speed reader (7) are incorporated other equivalent conventional systems, even modifying measuring parameters such as, for instance, by measuring minimum draught depressions, obstruction, air roughing, etc., similarly acting the power actuated system (5) upon the 30 extractor (6).

11 Amendments to the claims have been f lied as follows 1. A system for controlling forced-draught gas-oil heaters to be used for heating residential premises, including: an "all-or-nothing" electrical ly-actuated valve fitted between a gas-oil burner and a constant-flow regulator, fed by gas-oil from a reservoir; a motor-driven exhaust extraction unit adapted to generate an output signal dependent upon the speed of rotation of its rotor; a computer for comparing the actual rotor speed with that necessary to produce a desired draught, and a regulator controlling the motor voltage in dependence on the output signal, to stabilize the rate at which combustion gases are exhausted into the atmosphere.

2. A gas-oil heater system as claimed in claim 1, in which the extraction rotor speed is given by the rate at which a beam of radiation is broken by perforations in a disc rotated by the rotor to generate the desired output signal.