EP1108956A2

EP1108956A2 - Device for combustion control

Info

Publication number: EP1108956A2
Application number: EP00123642A
Authority: EP
Inventors: Mario Zucco
Original assignee: IMIT SpA
Current assignee: IMIT SpA
Priority date: 1999-12-13
Filing date: 2000-10-30
Publication date: 2001-06-20
Also published as: IT1314125B1; ITMI992580A1; EP1108956A3; ITMI992580A0

Abstract

A device for combustion control, especially for gas-fed boiler burners, comprises at least an optical sensor (10) constituted of one or more photodetectors, oriented in the direction of one or more defined zones of flame (12) of a boiler (14), whose electric signals supplied at the outlet are acquired by a card for a data elaboration system (16) based on neural networks and fuzzy logic, said system interacting with the electronic card (18) for the control of said boiler (14).

Description

The present invention relates to a device for the control of combustion.
More particularly, the present invention relates to an optical device for the control of the combustion of burners, especially those making part of gas-fed heating boilers.
As is known, the correct regulation of boiler burners is the base for limiting energy consumption and for the reduction in the emission of polluting substances. Today these problems are particularly felt, as air pollution, especially in towns, is caused to a large extent by heating systems with increasing frequency in winter. In such period, in fact, situations occur wherein the value of noxious substances in the air reaches and overcomes the attention threshold, causing the necessity of drastic interventions for the protection of public health. While specific norms provide for systems to be submitted to the control of yield and combustion, once or twice every year according to the power utilized, it is in practice impossible to maintain in boilers in a systematic manner a high-yield combustion, i.e. such as to produce minimum amounts of pollutants.
Especially for combined boilers, which in autonomous heating systems produce also sanitary hot water, combustion yields are low, because of the repeated on-off steps.
In the attempt at obviating these drawbacks, control devices have been proposed made up by chemical sensors suitable to detect the content in noxious gases comprised in the fumes determined by combustion. However, these devices have severe drawbacks, as they require a rather long reaction time and provide information on combustion yield only indirectly.
Hence, chemical sensors cannot step in promptly in the more critical stage, i.e. that wherefrom the combustion process starts. Another type of known control devices is based on the utilization of flame ionization temperature sensors.
However, in these devices, the revelation of flame temperature does not provide complete information on combustion quality, in particular as concerns the excess of combustion air which constitutes a basic parameter.
Object of the invention is to provide a solution for the aforementioned drawbacks of the control devices of the known art.
More particularly, object of the invention is to realize a device allowing to adjust in an optimal manner burner combustion, especially for burners applied to gas-fed heating boilers, obtaining complete indications on combustion quality.
A further object of the present invention is to realize a device for combustion control suitable to keep constantly monitored in real time the excess values of air and the yielding losses of combustion.
A further object of the present invention is to realize a device as defined above, suitable to adjust combustion continuously, depending on the value obtained, interacting with the electronic card of the boiler.
A not least object of the present invention is to provide users with a device for combustion control that can ensure a high level of resistance and reliability in the time, and also such as to be easily and economically realized.
In a general aspect, the present invention allows to achieve these and other objects that will be clear thanks to the following description by continuously monitoring the flame characteristics and correlating the flame optical characteristics with combustion quality in terms of air excess, obtaining in this way instantaneous complete information on combustion state through specific systems of data elaboration.
Therefore, object of this invention is a device for combustion control, especially utilizable for gas-fed boiler burners, comprising at least an optical sensor constituted of one or more photodetectors, oriented in the direction of one or more zones defined by the flame of a boiler, wherein the electric signal provided at the outlet are acquired by a card for a system of data elaboration based on neural networks and fuzzy logic, said system interacting with the electronic card that controls said boiler.
The constructive and functional characteristics of the device for the combustion control of the present invention will be better understood thanks to the following description wherein reference is made to Figure I that shows a block diagram of the device of the present invention according to a preferred nonlimiting example.
With reference to said figure, the device for the combustion control of the burners of the present invention, especially applicable to gas-fed heating boilers, comprise at least an optical sensor (10) suitable to detect the aspect of flame (12) of a boiler (14) in terms of color, form and size, preferably also of temperature.
Said optical sensor (10) interacts with a system of data elaboration (16) based on neural networks and fuzzy logic.
Said elaboration system (16) is connected to the conventional card (18) for the control of the boiler.
The optical sensor (10) is constituted of one or more photodetectors, preferably large-band photodiodes sensitive to the whole visible light spectrum (400-700 nm), associated to colored filters, red, green or blue, to select the part of spectrum one wishes to detect. Alternatively, photodetectors may be used that are sensitive to well-defined zones of the spectrum, i.e. for instance 400-500 nm for blue, 500-600 nm for green, 600-700 nm for red; in this case the filter is directly applied to photodetectors or photosensors. The latter, as is known, are semiconductor light radiation detectors, that transform the radiation incident on the sensitive part of the sensor into an outgoing electric signal proportional to the light intensity detected.
In its preferred embodiment, the optical sensor (10) of the device of the present invention comprises a triplet of photodetectors: R (20) (red), G (22) (green), and B (24) (blue), with separate outlets, so aligned as to be oriented and aimed at well-defined and prefixed zones of flame (12).
The photodetector or photodetectors are coupled to form one only sensor, advantageously incorporated in a supporting envelope (28), obtained from any suitable material and located in boiler (14), in the direction of the flame (12). The electric signals obtained at the outlet of the photodetectors, proportional to the light intensity incident on the same, are transferred to a data acquisition card, which data constitute the inlet values for the elaboration system (16).
Said elaboration system (16) is based on neural networks and luzzy logic, and can perform all the mathematical operations necessary to obtain the parameter related to air excess and acts directly on the electronic card (18) for the control of boiler (14), to adjust combustion quality. Such adjustment may for instance he due to a variation in the supply of combustion air or the opening of the gas valve.
Alternative solutions for the realization of sensor (10) may concern the presence of one only or two photodiodes, R or G or B. as well as the presence of a couple of photodiodes identical and associated with each other, according to any combination of R. G and B.
According to a further embodiment, the control device of the invention comprises, besides the sensor constituted by the aforementioned photodiodes, one or more temperature sensors (26) of the infrared or thermocouple type; in fact, the combustion yield depends on both the oxygen percentage and the difference between the temperature of outgoing fumes and air temperature.
The optical analysis as defined above, together with a measure of these temperature parameters, allows therefore to further evaluate exactly the yield values of the combustion. The temperature sensor or sensors (26) interact with the neural network of the fuzzy logic elaboration system (16), determining its action on the card (18) according to the same procedure as the signal coming from the photodetectors of photodiodes.
While the present invention has been described above with reference to a specific embodiment thereof, various alternatives and changes will be obvious to those skilled in the art in the light of the above description. Therefore, the present invention intends to comprise all those alternatives and changes that fall within the spirit and the protection scope of the following claims.

Claims

A device for the control of combustion, especially for gas-fed boiler burners provided with an electronic card (18) for the control of boiler (14), characterized in that said device comprises:

at least an optical sensor (10) constituted of one or more photodetectors, oriented in the direction of one or more zones defined by flame (12) of a boiler (14); and

a data elaboration system (16) based on neural networks and fuzzy logic, that acquires the electric signals supplied at the outlet by said at least one optical sensor (10), and interacts with the electronic card (18) for the control of boiler (14).
The device according to claim 1, characterized in that the photodetector or photodetectors of sensor (10) are constituted of large band photodiodes sensitive to the whole visible spectrum, and associated to color filters.
The device according to claim 1, characterized in that the optical sensor (10) is constituted of a triplet of photodetectors: R (20) (red), G (22) (green), and B (24) (blue), with separate outlets.
The device according to claim 1, characterized in that the optical sensor (10) comprises at least a photodiode R (20) (red), G (22) (green), and B (24) (blue).
The device according to claim 1, characterized in that the optical sensor (10) comprises a couple of identical a photodiodes R (20) (red), G (22) (green), and B (24) (blue).
The device according to any of the preceding claims, characterized in that the photodetector or photodetectors are coupled in a supporting envelope (28) located in boiler (14) in the direction of flame (12).
The device according to any of the preceding claims. characterized in that the optical sensor (10) is associated to at least a temperature sensor (26) connected to the data elaboration system (16).
The device according to claim 7, characterized in that said at least one temperature sensor (26) is of the infrared or thermocouple type and detects the temperature of fumes at the outlet and air temperature.