JPS60162122A - Controller for blower for forced-feed air type burner - Google Patents

Abstract

PURPOSE:To enable the excess rate of a primary air to be maintained at a given value, by a method wherein a flame rod is caused to face on a burner to detect a flame current value. CONSTITUTION:When the excess rate of a primary air, obtained by a terminal 14, becomes different from the set excess rate of the primary air of a comparator 16 resulting from a change in a gas pressure fed to a main burner 2, a voltage proportioning a deviation is generated, and a variation in the number of revolutions of a blower 5 is controlled, and the excess rate of the primary air is maintained at a specified value to provide excellent combustion. As noted above, the number of revolutions of the blower 5 for feeding the air to the burner 2 is varied and controlled according to a flame current produced by a flame rod 12, and even in case an amount of gas fed is changed due to a change in a feed gas pressure, the excess rate of the primary air can be maintained at a specified value, and proper combustion can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a blower for a forced air combustor, which forcibly supplies primary air to a burner using a blower to maintain a primary air excess ratio at a constant value for combustion. The present invention relates to a control device.

Conventionally, this kind of equipment has been designed to remove excess air in the combustion flame by setting the rotational speed of the blower so as to maintain the excess primary air ratio (supplied primary air amount/theoretical air amount) at a constant value of 1.0 or more. It is known that primary air is used to lower the flame temperature to lower the NO and x concentrations, thereby achieving good combustion.

However, in this case, if the actual amount of gas supplied to the burner changes due to a change in the gas pressure supplied to the burner, the rotation speed of the blower remains at the set value, so the primary excess air ratio shifts. If the primary air excess ratio shifts to the decreasing side, the NOx concentration increases due to the rise in flame temperature, and flashback is likely to occur, and if the primary air excess ratio increases too much, the flame temperature decreases. There is a problem in that the OO concentration increases due to flame lift-up and it tends to blow out, making it impossible to obtain good combustion.

The present invention has a conventionally known characteristic, that is, when a flame current value of the burner is detected when the flame current value of the burner is detected when the flame current value of the burner is detected when the flame current value of the burner is detected when the burner is ignited. Its absolute value changes depending on the input, but as shown in the first diagram, it has a mountain-shaped characteristic that peaks in the range of 1.0 to 1.1 for the primary excess air ratio. By using a flame rod to control the rotation speed of the blower according to the flame current value of the burner, the primary air excess ratio can be kept constant even when the gas pressure supplied to the burner changes. This method attempts to eliminate the above-mentioned inconvenience by maintaining the primary air excess ratio at a constant value, and the forced air supply system is designed to forcibly supply primary air to the burner using a blower to maintain the primary air excess ratio at a constant value during combustion. The gas type combustor is characterized in that a flame rod is provided facing the combustion surface of the burner, and the number of revolutions of the blower is controlled to increase or decrease in accordance with the flame current value of the burner.

The embodiments shown in FIGS. 2 and 3 in which the present invention is applied to a hot air heater will be described below.

fl) is the inlet (1a) on the back and the hot air outlet (1a) on the front.
The main body (1) houses a combustion case (4) containing a main burner (2) and a sub-burner (3), and a blower (5). By rotating the blower (5), indoor air is sucked through the suction port (1a), and hot combustion air from both burners (2) and (3) is sucked through the combustion exhaust port (4a) at the top of the nuclear combustion chamber (4). The two were mixed and blown into the room from the outlet (1bi≧).

In this case, the suction force of the blower (5) acts inside the combustion casing (4), and this acts on the inside of the combustion chamber (4) through the combustion surfaces (2a) (3a)'r of both burners (2) (31). The primary air is forced from the mixing tubes (2b) and (3b) to both burners (2b).
) (The primary air pressure is sucked into the blower 31, and thus the primary air pressure is increased or decreased depending on the rotational speed of the blower (5).

In this case, the primary excess air ratio of the main burner (2) was set to a constant value of 1 or more, for example 1.3.

In addition, the primary air excess ratio of the sub-burner (3) is 0.8 to 0.9.
It was set as the degree.

In the figure, (6) indicates a gas supply path connected to the gas nozzle (2o) of the main burner (2). A solenoid valve (8),
The governor (9) in the middle is completely interposed therein, and the auxiliary burner (3) is inserted between the governor (9) and the second solenoid valve (8).
) The gas supply path aO1 connected to the gas nozzle (6c) was branched.

0υ indicates a conventionally known temperature control circuit, which generates a signal according to the deviation between the actual room temperature and the set temperature, and this signal causes the first and second solenoid valves (7) (8 )
By changing the current flowing through each solenoid (7a) (8a), the opening degrees of the first and second solenoid valves (7) (8) are adjusted, and the amount of gas supplied to both burners (21 (3)) is adjusted. Control increase/decrease.

02 indicates a flame rod installed on the combustion surface (2a) of the main burner (2). 00 country indicates the rotation speed control circuit of the blower (5), which controls the flame current of the main burner (2). obtained from terminal a4,
This current is amplified by an amplifier circuit α9 and converted into a voltage.1 This voltage is inputted to the negative input terminal of the comparator ae as a voltage corresponding to the actual primary excess air ratio, and on the other hand, the voltage dividing resistor (17 ) (The voltage obtained at the ISO connection point A is input to the positive input terminal of the comparator Ql as a voltage corresponding to the primary excess air ratio, here 1.3, and the voltage obtained at the
A voltage is generated according to the deviation between the actual excess air ratio and the set excess air ratio, and this voltage can be used to change the terminal voltage of the motor σ of the blower (5), for example. and control the rotation speed of the blower (5) to 1
The amount of primary air is changed, and the primary air excess rate (1,
5).

Next, to explain its operation, the actual primary air excess rate obtained from the terminal α is changed to the primary air excess rate set by the comparator Qe due to changes in the gas pressure supplied to the main burner (2), etc. When the ratio differs from the primary air ratio, the comparator uO generates a voltage according to the deviation between the actual primary air excess ratio and the set primary air excess ratio, and this voltage controls the increase/decrease of the rotation speed of the blower (5). As a result, the primary excess air ratio is always kept at a constant value, and good combustion can be obtained.

In this way, according to the present invention, the rotational speed of the blower that supplies primary air to the burner is controlled to increase or decrease in accordance with the flame current obtained from the flame rod installed next to the burner. Even if the actual supply gas amount changes due to changes in the supply gas pressure, etc., the excess air ratio of the primary air can always be maintained at a constant value that provides good combustion, and this can be achieved by performing appropriate combustion control of the burner. have an effect.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between excess air ratio and 7 Ray input current value, Fig. 2 is a cut side diagram of an example of a combustor to which the device of the present invention is applied, and Fig. 6 is a diagram showing the relationship between excess air ratio and 7 Ray input current value. FIG. 3 is a diagram in which a circuit configuration is added to a front view cut away from a line 5; (2)...Burner (5)...Blower 0...Frame rod 103-

Claims (1)

[Claims] By forcibly supplying primary air to the burner using a blower,
In a forced air combustor that performs combustion while maintaining the excess air ratio at a constant value, a flame rod is provided facing the combustion surface of the burner, and the rotation speed of the blower is adjusted to the flame current value of the burner. A control device for a blower in a forced air combustor, characterized in that the blower is controlled to increase or decrease depending on the amount of air.