JPH0642732A - Method and device for preventing corrosion caused by dew formation at smoke chamber in hot air heater - Google Patents

Abstract

PURPOSE:To prevent a smoke chamber at a hot air heater from being etched by acid generated through dew formation of water vapor contained in combustion gas. CONSTITUTION:A donut-shaped buffle 28 is arranged at a smoke chamber 16A of a hot air heater 10. Combustion gas passes through a hollow part 28A of the buffle and flows along a tube plate 27 or a wall surface of a smoke chamber barrel 26, thereby temperatures of the tube plate 27 and the wall surface of the smoke chamber barrel 26 are increased and the dew formation water is prevented from being made at the wall surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for preventing corrosion due to the generation of dew condensation water in a smoke chamber of a hot air heater, and in particular, a smoke chamber of an agricultural warm air heater used for heating a greenhouse horticultural facility. The present invention relates to a method and an apparatus therefor for preventing dew condensation water from being generated in the exposed portion and causing corrosion of the portion in question due to acid.

[0002]

2. Description of the Related Art The applicant of the present invention has shown a front sectional view of FIG.
7A is a person who manufactures and sells the hot air heater shown in FIG. 7B, which is a side sectional view taken along the line BB of FIG. 7A, in which 10 is a hot air heater and 11 is a burner (for example, a gun). Type burner), 12 is a combustion chamber, 13 is a flame, 14 is a smoke tube, 15 is a screw plate, 16
Is a smoke chamber, 17 is a chimney, 18 is an air intake port, 19 is a blower, 20 is a hot air outlet, 21 is a smoke chamber lid, 22 is a flue elbow, 23 is a control panel, 24 is a duct, and 25 is a heat shield plate. , 26 is a smoke chamber body, and 27 is a tube plate.

In the warm air heater 10 shown in FIG. 7, fuel and air are mixed and ejected in a gun type burner 11 and ignited to form a flame in the combustion chamber 12, and combustion gas generated at that time is generated. Flows through the smoke pipe 14 and through the smoke chamber 16 as shown by the arrow 1, and the flow direction is changed by the flue elbow 22, and is discharged through the chimney 17 to the outside of the greenhouse where the warm air heater 10 is arranged. The air in the greenhouse, which is taken in from the air suction port 18 by the rotation of the blower 19, flows around the smoke pipe 14 and the combustion chamber 12 and is heated to become warm air, and as shown by the arrow 2, from the warm air outlet 20. It is supplied to the greenhouse by the duct 24 and heats the greenhouse.

[0004]

The combustion gas that has passed through the smoke pipe 14 gathers in the smoke chamber portion 16A, which has the smoke chamber 16 as a main portion, and the stack 17
Although it is discharged to the outside of the greenhouse through the combustion chamber, the flow of the combustion gas in the smoke chamber portion 16A is along the wall surface (the iron plate surface) of the tube plate 27 and the smoke chamber body 26 forming the smoke chamber portion 16A. Instead of flowing, it flows directly to the chimney 17 as indicated by arrow 1 in FIG. Therefore, the wall surface cooled by the cold air of the greenhouse taken in by the blower 19 has a low temperature rise due to passage of the combustion gas, so that the water vapor in the combustion gas is condensed on the wall surface. SO ₂ and SO ₃ in the combustion gas are dissolved in the dew condensation water created in this way to form H ₂ SO ₄ ,
This H ₂ SO ₄ corrodes the smoke chamber 16A.

In order to suppress the above-described cooling of the smoke chamber part, a method of blocking the flow of air hitting the smoke chamber part by a rectifying plate has been tried, but it has been found that a sufficient effect of preventing the formation of condensed water cannot be obtained. .

In order to raise the wall surface temperature, a method of raising the temperature of the combustion gas flowing into the smoke chamber was also tried. However, with this method, the temperature of the exhausted combustion gas is raised, the exhaust gas loss is increased, and the thermal efficiency is reduced, which is against the energy saving.

Under these circumstances, the present applicant has developed a can body corrosion prevention method for hot air heaters (Japanese Patent Application No. 1-144137 and Japanese Patent Application Laid-Open No. 3-11264). This method is characterized in that, in the operation of the warm air heater as shown in FIG. 7, the operation of the blower is started after a lapse of a predetermined time after the start of combustion of the burner. The control circuit and blower control circuit must be used.

The inventors of the present application focused on the following in order to achieve the object in preventing the corrosion of acid in the smoke chamber by preventing the generation of dew condensation water in the smoke chamber. That is, the dew point of water vapor in the combustion gas varies depending on the proportion of the sulfur content in the fuel oil, the higher the sulfur content, the higher the dew point temperature, and the combustion gas containing SO ₃ has a higher dew point temperature.

Therefore, an object of the present invention is to provide a method and an apparatus which are less likely to cause dew condensation even when fuel oil having a high sulfur content is burned because the fuel oil having a high sulfur content is likely to cause dew condensation. .

[0010]

According to the method of the present invention, a baffle 28 is provided in a smoke chamber portion 16A of a warm air heater 10 to combust combustion gas into the smoke chamber portion 16A.
It discharges from the chimney 17 along the wall of the tube and raises the temperature of the walls of the tube plate 27 and the smoke chamber body 26, thereby preventing the condensation of steam in the combustion gas in the smoke chamber 16A. In addition, the device of the present invention is equipped with a doughnut-shaped baffle 28 having a hollow portion 28A at the center thereof.
Smoke chamber flange 34 connected to tube plate 27 by
It is characterized in that the smoke chamber lid 21 is arranged on the opposite side of the tube plate 27 of the baffle 28 via the packing 33.

[0011]

That is, the present invention (1) by providing a baffle in the smoke chamber portion of the can body so that the combustion gas flows along the wall surfaces of the tube plate, the smoke chamber body, and the like that constitute the smoke chamber portion, (2) The combustion gas flows along the wall surface to increase the temperature of the wall surface. (3) The temperature increase of the wall surface prevents the condensation of water vapor in the combustion gas on the wall surface. The generated dew water reacts with the combustion gas SO ₂ to form H ₂ SO ₄ , which prevents the acid from corroding the smoke chamber. (A) The baffle in the smoke chamber prevents Change the flow of combustion gas, and without (b) baffle, the combustion gas passes through the smoke chamber and enters the smoke chamber. The combustion gas does not flow along the tube plate that constitutes the smoke chamber and the wall surface of the smoke chamber. Most of them flowed directly to the chimney and were discharged as exhaust gas outside the greenhouse. (C) The temperature of these wall surfaces is increased by allowing the flow of the combustion gas in the smoke chamber part to flow along the tube plate and the smoke chamber body, and (d) the tube plate and the smoke chamber body. Since the surface temperature (wall surface temperature) of the above becomes higher than the dew point of the combustion gas, dew condensation on these surfaces is prevented.

[0012]

The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1A is a front sectional view of the embodiment of the present invention.
7B is a sectional view taken along line BB in FIG. 7A, in which the same parts as those shown in FIG. 7 are designated by the same reference numerals and 28 is a baffle. In FIG. 1, the baffle 28 is simplified for the sake of simplicity.

The baffle 28 and the parts to be combined with it are shown in FIG. 2. FIG. 2A is an exploded perspective view of the baffle according to the present invention, FIG. 2B is a plan view, and FIG. The figure (B) is viewed in the direction of the arrow, and the figure (D) is an enlarged view of the portion of the circle D in the figure (C). In the figure, 29 is a fixture, 30 is a groove, and 31 is a fixed part. ,
33 is a packing and 34 is a smoke chamber flange. The baffle 28 is a doughnut-shaped baffle 28 with a shallow edge and a hollow portion (hole) 28A formed in the center. The attachment 29 includes a bottom portion 29A to which the baffle 28 is fixed by a fixing member 31 including a screw / washer / nut, and an upper side portion 29B extending above the bottom portion 29A and in a direction opposite to the bottom portion 29A. A groove 30 is formed in a portion connected to the upper side portion 29B. In the figure, packing 33
Although shown as a polygon, it is circular when combined with baffles as described below.

The method for setting the baffle is shown in the front sectional view of FIG. 3, and the figure (A) is a figure before the baffle is attached,
(B) is a diagram after the baffle is attached, and (C) is a circle C in (A).
The enlarged view of the part of FIG. 3D is the enlarged view of the part of the circle D of FIG. First, place the baffle 28 attached to the fixture 29 so as to face the tube plate 27 as shown in FIGS. 3 (A) and 3 (C), and then place the baffle 28 on the tube plate 27 as shown in FIG. 3 (B). Push the baffle until the connected smoke chamber flange 34 enters the groove 30 as shown by the white arrow in the same figure (C), and then the packing 33 (packing 33 is a replaceable part) and the smoke chamber lid 21. Install.

The baffle 28 is the same as the plan view of FIG. 4 (A) (B).
Is shown in detail in the front view of FIG. Hollow part 28A has a diameter D of 100 mm
, The height T of the periphery of the baffle is 10 mm, the thickness t of the periphery.
Was set to 0.6 mm and the outer diameter was set to 525 mm. The bottom of the fixture extends 38mm from the outer edge of the baffle shown at F in Figure (A).

5 (A), 5 (B) and 5 (C) are a plan view, a front view and a side view, respectively, of the fixture 29, in which 32 is a hole for the fixing part 31. The bottom portion 29A and the top portion 29B of the fixture 29 are U-shaped reinforcing portions, and the reinforcing portions are composed of two side portions 29C and connecting portions 29D of these side portions. Both sides
The distance W between the two outer sides of 29C is 21.6 mm, and the distance d between the inner sides is 20.
mm, the distance L between the outermost side and the inner side of the side portion 29C is 24.5 mm,
The length l of the bottom of the side portion 29C is 18.5 mm and the depth D of the groove 30 is 2
mm, the height H of the side portion 29C is 99.6 mm, and the height h of the groove 30 is 4 mm.
The distance M between the outer sides of the bottom portion 29A and the upper portion 29B is 78 mm, the length m1 of the bottom portion 29A is 48 mm, the length m2 of the upper portion is 30 mm, and the distance m3 between the centers of the two holes 32 is It was set to 28mm, and the upper and lower parts of the outside of the side part 29C were rounded.

FIG. 6 shows a baffle 28 attached to a fixture 29.
In the figure, (A), (B) and (C) are a plan view, a front view and a sectional view taken along the line CC of FIG. As described above, the inner diameter D of the baffle 28 was set to 525 mm, the width W between the outer parts of the attached mounting fixtures was set to 585 mm, and the height H of the mounting fixture 29 when mounted was set to 99.6 mm. Further, the peripheral portion of the baffle 28 and the back surface of the fixture 29 were brought into close contact with each other as shown in FIG.

In the illustrated embodiment, the flow of the combustion gas that has entered the smoke chamber 16 is changed by the baffle 28 installed in the smoke chamber, as shown by the arrow 1, and the tube plate 2
7. Flows along the wall surface of the smoke chamber body 26, thereby increasing the temperature of the wall surface. The rise in the wall temperature of the tube plate 27 and the smoke chamber body 26 prevents the condensation of water vapor in the combustion gas on these wall surfaces, and as a result, the corrosion of the acid contained in the condensed water is prevented. To be done. The flow of warm air shown by arrow 2 is the same as in the case of the example in FIG. 7.

The baffle 28 has a hollow portion in the center as described above.
(Hole) Since it is a donut-shaped disk with a hole 28A, the combustion gas flowing into the smoke chamber is (a) the hole 28A of the baffle,
(B) Flows through the gap between the baffle 28 and the smoke chamber body 26. Figure 1
(B) shows the tube plate 27 in this gap,
As shown in FIG. 2A, the tube plate is located rearward of the combustion gas outlet end of the smoke pipe 14 as seen in the flow of the combustion gas, and therefore is not related to the flow of the combustion gas indicated by the arrow 1 above. .

The hot air heater 10 shown in FIGS. 1 and 7 is a product manufactured and sold by the applicant of the present invention, which has a heat output of 87,000 Kcal / h, one of which is shown in FIG. In baffle 28
Was attached, and the other one was subjected to a comparative experiment without baffles as shown in FIG. The results are shown in Table 1.

[0021]

[Table 1]

[0022]

EFFECTS OF THE INVENTION According to the present invention, the amount of dew condensation water generated is 6.3 ml without baffles when the air ratio is 1.29.
With baffle, it becomes 0 ml, and when the air ratio is 1.16, what was 12.4 ml without baffle is 1.
4 ml (about 1/9), smoke chamber body 26 and tube plate 27
An average temperature of 40 to 60 ° C. was measured by adding the baffle 28, and the thermal efficiency was increased by about 1% by adding the baffle. Also, even with a baffle, the combustion chamber
It was confirmed that the pressure in 12 was unchanged or only slightly increased, and that the baffle did not significantly resist the flow of combustion gases.

Explaining the air ratio, the required air amount in complete combustion without excess air of the fuel oil is calculated by the theoretical air amount Lo.
It is called [Nm ³ / kg]. In actual combustion, more air is required than the theoretical amount of air for complete combustion, which is called the actual air amount L [Nm ³ / kg]. The air ratio m is the ratio of the actual air amount and the theoretical air amount and is represented by the following equation.

[Equation 1]

The air ratio is obtained by measuring the CO ₂ volume ratio in the combustion gas (exhaust gas) and is represented by the following equation.

[Equation 2] Here, CO ₂ : CO ₂ volume ratio in combustion gas [%] CO ₂ max: CO in combustion gas completely combusted without excess air
₂ Volume ratio [%]

Since CO ₂ max of general A heavy oil is 15 to 16%, it is treated here as CO ₂ max = 15.5%. CO ₂ max depends on the composition of fuel oil and the ratio of C and H. The relationship between CO ₂ and O ₂ in the combustion gas is based on the Ostwald combustion triangle.

[Equation 3] Here, it is represented by O ₂ : O ₂ volume ratio [%] in the combustion gas.

Therefore, by measuring the O ₂ concentration in the combustion gas (exhaust gas), CO ₂ can be obtained by the equation 3, and the air ratio can be obtained by the equation ₂ . The reason why CO ₂ is not measured directly is that O ₂ measurement is simple and accurate.

The air ratio is used to calculate the thermal efficiency of the heater.
The thermal efficiency μ [%] is obtained from the ratio of the amount of heat exhausted to the outside from the chimney of the heater (exhaust gas loss ε [%]).

[Equation 4]

As a method of calculating the exhaust gas loss, the applicant uses the following approximate expression based on theory and practice.

[Equation 5] Where: m: air ratio tg: exhaust gas temperature [° C] to: atmospheric temperature [° C]

In order to improve the heat efficiency of the heater, from the equation 4 to ε
To reduce ε, decrease the air ratio (m) from equations 5 and 1 (complete combustion with an air amount close to the theoretical air amount) lower exhaust gas temperature (tg) (heat It is possible to increase the efficiency of the exchanger). However, generally, when the air ratio is lowered, the exhaust gas temperature tends to be lowered, and reducing the air ratio is an effective means for reducing the exhaust gas loss and increasing the thermal efficiency.

Regarding the relationship between the generation of dew condensation water and the air ratio, the exhaust gas temperature decreases as the air ratio decreases and the efficiency increases. When the exhaust gas temperature decreases, the temperature of the chimney wall surface decreases,
Condensation becomes easy. The data in Table 1 was obtained under such severe conditions.

[Brief description of drawings]

FIG. 1 is a diagram of an embodiment of the present invention, in which FIG.
FIG. 7B is a sectional view taken along line BB of FIG.

FIG. 2 is a diagram of a baffle and a fixture according to the present invention.
(A) is an exploded perspective view, (B) is a plan view, (C) is the same figure.
FIG. 7B is a view as seen in the direction of the arrow, and FIG. 6D is an enlarged view of the portion of the circle D in FIG.

3A and 3B are views showing the order of fixing the baffle of the present invention to the smoke chamber, where FIG. 3A is a front sectional view before fixing, FIG. 3B is a front sectional view after fixing, and FIG. ) Is an enlarged view of a portion of a circle C in FIG. 7A, and FIG. 7D is an enlarged view of a portion of a circle D in FIG.

FIG. 4 is a diagram of the baffle of the present invention, in which FIG.
FIG. 3B is a front sectional view.

FIG. 5 is a view of a fixture for the baffle of the present invention, which shows the same.
(A) is a plan view, (B) is a front view, and (C) is a side view.

6A and 6B are views showing a state in which a fixture is fixed to the baffle of the present invention, where FIG. 6A is a plan view, FIG. 6B is a front sectional view, and FIG. 6 is a cross-sectional view taken along the line CC of FIG.

FIG. 7 is a front sectional view of a hot-air heater according to the development of the applicant.

[Explanation of symbols]

 10 Warm air heater 11 Burner 12 Combustion chamber 13 Flame 14 Smoke pipe 15 Screw plate 16 Smoke chamber 16A Smoke chamber part 17 Chimney 18 Air intake port 19 Blower 20 Warm air outlet 21 Smoke chamber lid 22 Flue passage elbow 23 Control panel 24 Duct 25 Heat shield 26 Smoke chamber body 27 Tube plate 28 Baffle 28A Hollow part (hole) 29 Fixture 29A Bottom part 29B Top part 29C Side part 29D Connection part 30 Groove 31 Fixing part 32 Hole 33 Packing 34 Smoke chamber flange

Claims (2)

[Claims] 1. A tube plate (27) and a smoke chamber body (26) which form a smoke chamber portion (16A) by providing a baffle (28) in the smoke chamber portion (16A) of a warm air heater (10). ) Is discharged from the chimney (17) along the wall surface of (1) and raises the temperature of the wall surfaces of the tube plate (27) and the smoke chamber body (26), whereby the smoke chamber (1
6A) A method for preventing corrosion due to the generation of dew condensation water in the smoke chamber of a warm air heater, which is characterized by preventing dew condensation. 2. A doughnut-shaped baffle (28) having a hollow portion (28A) formed in a substantially central portion thereof is attached to a smoke chamber flange (34) connected to a tube plate (27) by a fixture (29), and the baffle is attached. Due to the generation of dew condensation water in the smoke chamber part of the warm air heater, which is characterized in that the smoke chamber lid (21) is arranged on the opposite side of the tube plate (27) of (28) through the packing (33). Corrosion prevention device.