JPS6016218A - Combustion control device - Google Patents

Abstract

PURPOSE:To keep the excess air ratio of primary air within good combustion range by a method wherein the rotational frequency of a blower to supply primary air to an entire combustion by primary air type burner is controlled in response to the output of a heat-sensitive element to detect the flame temperature of the burner. CONSTITUTION:A heat-sensitive element 13 such as thermocouple or the like is provided fronting on an entire combustion by primary air type burner 2 in order to control a blower 4 by changing its rotational frequency in response to the output of the heat- sensitive element 13. Concretely, a rotational frequency command circuit 14 to generate a rotational frequency command signal in response to the output of the heat-sensitive element 13, a rotational frequency detection circuit 16 to generate a signal responding to the actual rotational frequency of the blower 4 based upon the output of a pick-up coil for the detection of the rotation of the blower 4 and a differential amplification circuit 17, to which the signals from both the circuits 14 and 16 are inputted, are provided so as to put the transistor 18 into actuation in order to control the rotation of the driving motor 4a of the blower 4 based upon the output of the differential amplification circuit 17 in such a manner that the rotational frequency of the blower 4 is changed so as to bring the deviation between the signals from both the circuits 14 and 16 to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control device for a combustor using all primary air combustion type burners.

Conventionally, this b (as a combustor, for example, JP-A-57-192
According to Publication No. 741, a blower that forcibly supplies primary air to all primary air combustion type bars is installed, and the excess air ratio (supplied air M/theoretical air amount) is set to 1.0 or more to suppress the combustion flame. The excess primary air inside reduces the flame temperature and reduces NOx.
It is known that the concentration can be lowered, but in this case, if the excess air ratio is reduced, the flame temperature increases and NOx
As the temperature of 774 degrees increases, inversion tends to occur, and if the excess air ratio increases too much, the flame temperature decreases, increasing the 00 concentration and blowing out due to flame lift-up, which leads to good combustion. To obtain this, it is necessary to set the excess air ratio within a certain range. Therefore, when controlling the amount of gas supplied to the burner, the amount of primary air supplied must also be increased or decreased to maintain a constant excess air ratio for good combustion. It is necessary to keep it within the range.

One way to do this is to change the rotation speed of the blower according to the amount of supplied gas, but even if the amount of supplied gas is the same, if there is a difference in gas components, the theoretical air amount will change. In the method of changing the rotation speed of the blower according to the amount of gas, not only the gas type can be changed, but also gases 1 (gas that tends to combust incompletely), 2 gas (gas that easily flashbacks), and 3 gas (gas that is prone to flashback) are changed. The excess air ratio may deviate from the good combustion range due to the difference in gas fraction among the three test gases (gases that easily blow out).

The present invention focuses on the fact that the flame temperature changes as described above due to changes in the excess air ratio, and uses a heat-sensitive element to increase or decrease the rotational speed of the blower according to its output. The purpose of this invention is to provide a Trik system that can always maintain the excess air ratio within a good combustion range regardless of the difference, and will be described below with reference to fully illustrated embodiments of the present invention.

The drawings show an embodiment in which the present invention is applied to a combustion control device for a hot air heater incorporating a full primary air combustion type burner, (1)
is a heater main body equipped with a back suction port (1a) and a front hot air outlet (1b), in which a total of 1
Next, the air combustion type burner (2) is completely built into the combustion case (3),
A blower (4) is housed therein, and by the rotation of the blower (4), air inside the tube is drawn from the suction port (1a) and further into the combustion casing (3).
) The combustion hot air of the burner (2) is sucked through the combustion exhaust port (5a) at the top of the burner (2), and the heel is mixed with the air outlet (1b).
It was made to blow out into the room.

In this case, the suction force of the air blower (4) acts inside the combustion case (3), which causes the combustion surface (2a
)'<ru.

The gas supply path (5) leading to the burner (2) includes a first solenoid valve (6) on the upstream side, a second solenoid valve (7) on the downstream side, a gas cock (8) in the middle, and a gas valve. (9), and a side passage (I[l) is provided in parallel to the second solenoid valve (7), and when this falls below the set temperature depending on the temperature, the second solenoid valve (7) is fully opened. When the temperature exceeds the set temperature, the solenoid valve (7) is fully opened to increase the amount of gas supplied to the side passage (2) to, for example, 30,007 Vh in terms of calories. The amount of supplied gas is reduced to, for example, 1s o ob+/h by gas supply, and when the room temperature further rises, the first solenoid valve (6) is closed and the burner (2) is closed.
now stops burning.

In the drawing, α1) (12 is the detection for the oxygen deficiency safety device) gas and flame detection clamp are shown.

According to the present invention, the all primary air combustion type burner (
2) A thermocouple or other heat-sensitive element (131) is provided, and the number of revolutions of the blower (4) is controlled to increase or decrease according to the output of the heat-sensitive element (131). In order to control the increase and decrease according to a predetermined proportional characteristic according to the output of the heat sensitive element α3), it is configured as follows.That is, according to the output of the heat sensitive element α3), the rotation speed according to the proportional characteristic shown by the line a in FIG. Rotation speed command circuit (l
The drive motor (4) of the blower (4) is controlled by the output corresponding to the actual rotational speed of the blower (4) by the outputs of the a, the blower K fi (rotation detection pickup coil 09 force of 41), etc.
The power transistor 4181''e for rotation control is activated to increase or decrease the rotation speed of both circuit circles (W glare 1 and 4 so that the deviation of the signal from IQ becomes zero), or <-c. re
.

According to a change in the output of the thermal element 03), the rotation speed of the blower (4) is controlled to increase or decrease along the proportional characteristic line &.

Next, we will explain its operation, but first, we will use five types of test gases, 13A gas, and adjust the supply gas amount of each gas to 600.
0 day/h and 1,500 kI/h, and in each case, the rotation speed of the blower (4) was within the good combustion range of (2) (approximately 1.02 to approximately 1.5 in terms of excess air ratio). range)
The results of an experiment in which the output of the heat-sensitive element (13) was measured while varying the temperature will be explained. In addition, the components of the test gas are 1
Gas is OH, as%-(], H815%, 2 gases are 87
30%-0H455%-〇, H815%, 6 gases are 0H
498% - N22%, and the theoretical air @ (air IT/gas amount) is 1 gas is 11.72.2 gas is 9.553.
5 gas is 9.564.

The results are shown in Figure 5, hII hII
"4 is the change characteristics of 1 gas, 2 gas, and 5 gas at 5000 hl/h, t8.t2.ts is 1500kr21
/h Shows the change characteristics of R for 1 gas, 2 gas, and 5 gas.

As is clear from the figure, the number of revolutions required for good combustion increases in the order of 1 gas, 2 gas, and 5 gas due to the difference in theoretical air amount. At 5000kcd/h, the number of revolutions required for good combustion is in the range of 1 gas. If the rotation speed is controlled according to the amount of supplied gas, for example, the rotation speed at 4 o'clock on the 3000th day will be within the rotation speed range of 6 gases. If this is set, if 1 gas is used, the excess air ratio will fall below the lower limit of the good combustion range, making flashback noise likely to occur, and if this is set to the rotational speed range of 1 gas, the excess air ratio will be lower when each 6 gas is used. It can be seen that when the upper limit of the good combustion range is exceeded, blowout tends to occur, and the rotation speed cannot be controlled appropriately with such a control method.

On the other hand, the output range of the heat-sensitive element Q3 in the good combustion range is not much different for each gas. It is increased or decreased by feedback control, that is, when the output increases from the output standard a+b of 25 mV in Fig. 6, the rotation speed is increased, and when the output decreases from the ridge line, the rotation speed is lowered so that the output is always 25 mV. If the rotational speed is controlled to increase or decrease so that Blow-out is likely to occur due to overshoot in the rotational speed due to overshoot control, and it is necessary to devise ways to reduce the overshoot. That is, the rate of change in output with respect to a change in rotational speed increases as the rotational speed increases, and near the upper limit, a slight increase in rotational speed causes blowout, and this tendency becomes more noticeable as the amount of supplied gas increases. However, on the 3000th day, the overall output increased compared to the 1500th day/hour, and the
Even if all the reference values are set in the output range where the output change rate is relatively small at 5001 cal/h, the reference value will enter the range where the output change rate is large at 3000 days/h, and if the rotation speed overshoots, it will blow up. The money disappears and becomes the owner of the money.

On the other hand, if the rotational speed is controlled to increase or decrease in proportion to the output as in the above practical example, the proportional characteristic can be expressed as the change characteristic line hl at 300 ad/h for each gas.
It is possible to perform reliable control by setting the change characteristic line Zl r 72 r '3 at 15001 ol/h to intersect with each other in an output region where the output change rate is relatively small. Become.

To explain this in more detail, for example, if 1 gas is supplied 1 gas is 1 gas.
At 500 hl/h, the output of the heat sensitive element edge and the blower (
The rotation speed in 4) is the value at the intersection x1 of the line a and the line t1.If the supplied gas amount increases from this state to t-3ooo days/h, the output will increase and the rotation speed will change along the line a. increases,
When the value of the intersection point Y between the line a and the line h1 is reached, the output becomes stable and combustion continues at the value Y. Conversely, when the amount of supplied gas is decreased from 3000 days/h to 1500 days/h, the output rotation speed decreases along the line a from the value of Yl and becomes stable at X. And in this case x1, Y
Since both hl and 4 exist in a relatively small range of output change rates, overshoot does not cause blowout or backfire.

The same is true for 2 gases and 3 gases, and in the case of 2 gases, due to the change in the supply gas, each intersection of this and 1 and Hanawa along line a.
The output and rotational speed change between 21 Y2 and each intersection X3+Y3 of t3 and h3 along the Vi line a for the three gases.

In addition, in the above embodiment, the heater's warm air circulation blower +41'
Although the combustion blower was also used to forcefully supply primary air to the burner 121, a combustion blower was provided separately and its rotational speed was controlled to increase or decrease according to the output of the heat-sensitive element as described above. Furthermore, the present invention can be applied not only to heaters but also to other combustors that use all primary air combustion type burners.

As described above, according to the present invention, the rotational speed of the blower that supplies primary air to all primary air combustion type burners is controlled to increase or decrease according to the uj force of the heat-sensitive element facing the burner.
Regardless of differences in gas components or changes in the amount of supplied gas, the excess air ratio of the primary air can always be maintained within a good combustion range, and the burner can be appropriately controlled for combustion.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional side view of an example of a combustor to which the present invention is applied, Figure 2 is a cross-sectional front view taken along the line ■-■ in Figure 1, with a circuit configuration added, and Figure 6 is a thermosensitive FIG. 6 is a diagram showing the characteristics of changes in the output of the element and the rotational speed of the blower. (2)... Total primary air combustion unit (4)... Blower (131... 2 persons other than heat sensitive element procedural amendments Showa 5Isu 2+414 Japan Patent Office and 7814.. 1 , Indication of the case 1982 Patent Application No. 123931 2, Title of the invention: 1 theory 1 lrl J value device 3, person making the amendment 8! 4. Agent 5. Amendment order with H (eye button) Il' tlil of the invention in the specification dated 1925-2017 7J: nQ ”J
J arrangement VC diagram ITI+ (1) Il'1 middle theory 1! l
]'s +l! g, the eye surface, and the contents of the correction 1, set 4, book 1 ε1) page 10, line 5, θ (to f
ti+J mentioned is discharged by blower (4) j/,■(
IaJ force, indoor air, and further combustion of two parts of the combustion case (3) 1Jul air 1-1 (5A) to the burner (2
), the combustion hot air is sucked in, and the indoor VCC is output from the air outlet (1a) with both t7 mixed awns. -1451,]v
c. The blower blows out hot air 4, Cl1l building, 1
〉After taking in all the combustion air from outside the room,
Exclusive air blower that supplies and exhausts 11〆, 100+ 1ljl! :Q 141 'v: niノ;11□ and times t'1
< to! Is the same result even if I use Ifli tli? II et al. 1. This is not a box that claims to be a thing. In addition, the missing member will be added. 2 Specification-44”, θ of “Boss diagram” in Figure 3, page 11
〈〈, Figure 4 is a comparison of other examples <1'if Ij・
Listening + + 1. '4% Figure 5 shows this ■-V line positive [
11J1 route analysis 戊 KE L] Add fc diagram to the 1 diagram. The attached Figures 4 and 5 are all attached to the 5th drawing.

Claims (1)

[Claims] 1. An all-primary air combustion type burner and a blower for supplying primary air to the burner for strong i1i purposes, and are configured to increase or decrease the gas ffi' supplied to the burner. A combustion control device characterized in that a thermocouple or other heat-sensitive element is provided facing the burner, and the rotational speed of the blower is controlled to increase or decrease depending on the power of the heat-sensitive element. 2. The combustion control device according to claim 1, wherein the rotation is controlled to increase or decrease according to a predetermined proportional characteristic according to the output.