JPH0311264A - Corrosion preventive method of shell of warm air type heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] A method for preventing corrosion of the can body of a hot air heater, for example, when starting the operation of a hot air heater for heating a greenhouse for greenhouse horticulture, the operation start time of the hot air heater and the blower is determined. Regarding the method of preventing corrosion of the can body by controlling the operation of the hot air heater and the blower to avoid loss of the rear part of the can body due to simultaneous operation of the hot air heater and the blower, The purpose is to provide a method to prevent corrosion of the can body, and the combustion gas generated in the combustion chamber of a warm air heater placed indoors is discharged outside the room through the smoke pipe, smoke chamber, chimney connection port, and chimney. On the other hand, in the operation of a warm air heater configured to bring the air in the room into contact with a smoke pipe and blow it into the room from the hot air outlet, the blower starts operating after a predetermined period of time has elapsed after the start of combustion in the burner. The present invention includes a method for preventing corrosion of a can body of a hot air heater, characterized in that:

[Industrial application field]

The present invention provides a method for preventing corrosion of the can body of a hot air heater, for example, when starting the operation of a hot air heater for heating a greenhouse for greenhouse horticulture, the can body is Concerning a method for preventing corrosion of.

[Conventional technology]

In greenhouse cultivation for greenhouse horticulture, hot air heaters are used alone or in conjunction with heat exchangers during the winter. In FIG. 3, a hot air heater 20 manufactured and sold by the present applicant is partially shown in cross section, and in the figure, 21 is a burner, 22 is a control box containing a burner circuit for the burner 21, etc.; 24 is a combustion chamber made of aluminized steel, and 25 is a furnace pressure adjustment port.
is a smoke pipe made of aluminized a etc. with the screw plate shown inside (acts as a heat exchanger)
, 26 is a smoke chamber made of aluminized 11, 27 is a chimney connection port with a chimney (not shown), 28 is a hot air outlet whose blowing direction can be freely changed, and around the smoke pipe 25 are a plurality of other smoke pipes 25a. is installed. For example, heavy oil is combusted in the combustion chamber 24 using the burner 21, and the high-temperature combustion gas is guided to the smoke chamber 26 via the smoke pipe 25.25a, and then discharged outside the greenhouse through the chimney connection port and a chimney (not shown). .

On the other hand, a blower 31 is coupled to the illustrated warm air heater 20 . When the hot air heater 20 starts operating, the blower 3
1 is turned on, the air in the greenhouse is sent towards the smoke pipe 25 in the direction of the arrow, and the air exchanges heat with the smoke pipe 25.25a.
The warm air is blown into the greenhouse from the hot air outlet 28. The direction of the hot air outlet 28 can be freely changed, and hot air is sent toward a desired part of the greenhouse.

[Problems to be Solved by the Invention] Conventionally, the blower 31 was operated at the same time as the burner combustion without particular consideration being given to the timing of burner combustion and blower operation.

Then, the air in the greenhouse that has not yet been heated by the blower 31 is transferred to the part of the heater can 29 where the smoke pipe 25.25a is placed, especially to the smoke chamber 26 and the smoke pipe, which are heated late after the start of combustion. 25. The connecting part of 25a, that is, the part that heats up the slowest, is cooled, and the combustion gas in the smoke pipe located at that part condenses, and condensed water is generated.
．． This occurs earliest at the connection between the smoke chamber 25a and the smoke chamber 26. If the fuel contains sulfur, the sulfur dioxide gas generated by combustion reacts with the condensed water in the smoke pipe to form sulfurous acid or sulfuric acid, resulting in a particularly corrosive dilute sulfuric acid state that can damage the rear part of the smoke pipe and the smoke chamber. corrodes, and eventually holes form. Recently, in order to increase thermal efficiency, the combustion gas temperature has been lowered (for example, 250
In addition, greenhouses tend to be operated under low load conditions, and the operating time of the heater is short. In the early stages, condensation water is likely to occur.

If combustion gas leaks through the holes in the smoke pipe, it will damage the crops in the greenhouse. In addition, the lifespan of the can body will be shortened to about two years due to damage to the smoke pipe due to condensation. Generally, cans are designed and manufactured to have a lifespan of 10 to 15 years, but if the lifespan becomes as short as 2 years, it is a great economic loss.

In order to avoid the above-mentioned problems, smoke pipes are made of aluminized material, but the above-mentioned damage to the smoke pipe still occurs. In particular, efforts are made to perfect the connection between the smoke pipe and the smoke chamber 26 by welding, etc., but since the connection between the smoke pipe and the smoke chamber 26 heats up the slowest, Condensation water forms most quickly in that area, which can lead to serious accidents such as combustion gas leaks.

Therefore, the present invention provides a method for controlling the operation of a hot air heater and a blower in order to avoid loss of the can body due to the simultaneous start of operation of the hot air heater and the blower, and preventing corrosion of the can body. The purpose is to

(Means for Solving the Problem) The above problem is to exhaust the combustion gas generated in the combustion chamber of a warm air heater placed indoors to the outside of the room through the smoke pipe, smoke chamber, chimney connection port, and chimney, and to In operation of a hot air heater configured to bring the air in the room into contact with a smoke pipe using a blower and blow it into the room from a hot air outlet, the blower starts operating after a predetermined period of time has elapsed after the start of fueling the burner. The problem is solved by a method for preventing corrosion of the can body of hot air heaters.

[Operation] That is, according to the method of the present invention, the smoke pipe is not cooled by the blower immediately after combustion starts, and the temperature of the wall of the smoke chamber at the rear of the can body portion 29 increases quickly in terms of the flow force of the combustion gas. Since the air blower starts blowing air after the can body is sufficiently heated, condensation is prevented.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1 is a circuit diagram of an embodiment of the present invention, in which 11 is a power supply;
2 is an operation switch, 13 is a burner limit switch which also has the function of preventing overheating of the can body 29 (Fig. 3), 14 is a timer, 15 is a burner control circuit, 16
1 is a blower control circuit, and 17 is a fan switch. Moreover, FIG. 2 is a diagram showing the temperature of the inner wall of the smoke chamber 26 of the heater. In the same figure (a), the horizontal line at the top indicates ON and OFF of the burner combustion (only ON is displayed, the part without display is OFF, and the two lines A' and B' described below) ], the horizontal line A' in the middle is a line indicating ON and OFF of the blower according to the present invention, and the horizontal line B' at the bottom is a line indicating ON and OFF of the blower according to the conventional example. This is a line indicating OFF. In the figure (b), the horizontal axis shows time in [minutes], and the vertical axis shows smoke chamber wall temperature in [°C].

In the conventional method, the controlled temperature inside the greenhouse is set to 25°C, for example.
and turn on the burner combustion accordingly.

The blower was repeatedly turned off, and the blower was turned on at the same time as the burner combustion was turned on. When the temperature inside the greenhouse reaches the above-mentioned control temperature after a certain period of time, the burner combustion is turned off, but the blower remains on to utilize the residual heat in the can, and the can When the temperature reaches a certain level, the blower stops operating (turns off).

As time passes and the temperature inside the greenhouse begins to drop below the control temperature, the burner combustion is turned on and the blower is turned on at the same time, and the cycle described above is repeated, and a separate circuit is prepared for this purpose. was. The change in the smoke chamber wall temperature in this case, as shown by line B in Figure 2(b), increases from about 30'C to about 145°C, then decreases to 30°C, and then rises to 145°C. rises to
I repeated it after that. The above-mentioned problem was experienced with turning on the blower at the same time as the burner was firing.

In the method of the present invention, the circuit shown in FIG. 1 is used to control combustion in the burner and operation of the blower. It is assumed that the hot air heater shown in FIG. 3 is used to control the temperature of the greenhouse as in the case of the conventional example described above. A sensor (not shown) for detecting the temperature inside the greenhouse is arranged in the greenhouse, and the sensor is connected to the burner control circuit I5.
The greenhouse control temperature is also stored in the burner control circuit. When the temperature inside the greenhouse drops to the control temperature,
The burner control 1211 circuit operates and the burner starts burning.

However, the blower remains OFF at that time, a condition represented by line A in FIG.

The time when the burner starts burning, approximately 1 in the diagram in Figure 2.
Minutes and 45 seconds have passed (at that time the smoke chamber wall temperature is 120'C)
2), the timer 14 closes, the fan switch 17 closes, and the blower starts operating.

The blower control circuit 16 is a circuit for controlling this series of operations. Line A in Figure 2 shows the change in temperature when implementing the method of the present invention, and in Figure 2 (a), line A' is in the OFF state without following the burner combustion when it is ON. , it turns ON after the above-mentioned time has elapsed. Therefore, the smoke chamber wall temperature does not continue to rise as shown by line C in FIG. 2(b), but continues to rise in a manner similar to line B at a slightly higher level than line B.

When the temperature in the greenhouse rises, the burner combustion is turned off as in the conventional example, but the blower continues to operate as in the conventional example, and is turned off at the same time as in the conventional example.
Thereafter, the above cycle is repeated.

In the above example, the blower started operating approximately 1 minute and 45 seconds after the start of burner combustion, but generally the fuel amount is 1 ffi/h.
1 minute to 2 minutes per can weight of 8 to 9 kg
Set within the range of 0 seconds. Further, although the above example has been explained using indoor heating of a greenhouse as an example, the scope of application of the present invention is not limited to that case, but also extends to cases of other purposes.

(Effects of the Invention) As described above, according to the present invention, since there is no generation of condensed water in the smoke chamber at the rear of the can body, there is no reaction between sulfur dioxide gas and condensed water, and sulfuric acid corrosion is prevented. This has the effect of avoiding damage and extending the life of the hot air heater.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram of wall temperature in a smoke chamber of a hot air heater, and FIG. 3 is a partially sectional front view of the hot air heater. In the figure, 11 is a power supply, 12 is an operation switch, 13 is a burner mint switch, 14 is a timer 15, a burner control circuit, 16 is a blower control circuit, 17 is a fan switch, 20 is a hot air heater, 21 is a burner, 22 is a control box, 23 is a furnace pressure adjustment port, 24 is a combustion chamber, 25.25a is a smoke pipe, 26 is a smoke chamber, 27 is a chimney connection port, 28 is a hot air outlet, 29 is a can body, and 31 is a blower. .

Claims (1)

[Claims] Combustion chamber (24) of hot air heater (20) placed indoors
The combustion gas generated in the smoke pipe (25, 25a) and the smoke chamber (2
6), the air is discharged outside the room through the chimney connection port (27) and the chimney, and the air inside the room is sent to the smoke pipe (25) using the blower (31).
, 25a) and blows hot air into the room from the hot air outlet (28), the blower (
31) A method for preventing corrosion of a can body of a hot air heater, characterized by starting the operation of the method.