JPH037845B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is easily absorbed by water and organic substances, so
The present invention relates to a device that generates far-infrared rays using combustion heat of fuel, which has recently been used as a heat source for heating the human body and various objects, that is, a far-infrared radiator that uses combustion heat as a heat source.

BACKGROUND OF THE INVENTION In recent years, light in the long wavelength region of infrared rays, called far infrared rays, is being used as a heat source for heating the human body and various organic substances.

Far-infrared light with a wavelength of 4 to 10 micrometers is particularly easily absorbed by water and organic matter, and it can be used to irradiate the human body with light of this wavelength for heating, or as a heat source for saunas, and to irradiate organic matter to dry it. It is also used for painting, printing, etc.

The wavelength of light is determined by the temperature of the object that generates the light, and according to Vienna's displacement law, among the light emitted from an object with a temperature of about 450 degrees Celsius, light of about 4 micrometers is emitted the most. An object at around 210 degrees Celsius emits the largest amount of light at around 6 micrometers.

Far infrared rays around 6 micrometers are easily absorbed by water and organic matter, so they are used to irradiate the human body for heating and sauna bathing, and to irradiate organic matter for drying and baking.

It is easy to maintain the temperature of the heater at around 210°C with a far-infrared radiator that uses electricity as a heat source, but with a far-infrared radiator that uses the combustion heat of fuel as a heat source, it is difficult to maintain the surface temperature of the radiator at a constant temperature. It is difficult to maintain the temperature at

This is because the temperature of a combustion flame is usually around 1,500 to 2,000 degrees Celsius, so unless water cooling or forced air cooling is used, the outer surface temperature of the combustion chamber will usually be around 800 to 1,500 degrees Celsius, which is significantly lower than the 210 degrees Celsius mentioned above. This can cause not only wavelength problems but also the risk of burning out the combustion chamber.

On the other hand, the temperature of the radiator near the exhaust section is preferably as low as possible, and is generally around 150°C, since the lower the exhaust gas temperature, the better the thermal efficiency.

Therefore, in order to obtain a far-infrared radiation device that uses the heat of combustion of fuel with good thermal efficiency, it is necessary to lower the temperature of high-temperature parts such as the outer surface of the combustion chamber.

One method of lowering the outer surface temperature of the combustion chamber is to further provide an inner cylinder inside the cylindrical combustion chamber, use the inside of the inner cylinder as the combustion chamber, and add a cooling tube between the inner cylinder and the outer cylinder. Air is forced to flow to cool the outer surface of the inner cylinder and the inner surface of the outer cylinder, and the high-temperature combustion gas flows out from inside the inner cylinder at the inner cylinder outlet, which is at least as long as the distance for complete combustion. There is a method of lowering the temperature of the combustion gas by merging with the combustion gas and heating the combustion cylinder to a lower appropriate temperature (see FIGS. 6 and 7 below).

Using this method, the temperature of the downstream radiator can also be lower than when no cooling air is used.

To give a specific example, by forcing 2 to 3 times the theoretical amount of air required for combustion between the inner and outer cylinders, the temperature of the outer cylinder surface is maintained at around 450 to 550 degrees Celsius, even in high places.
Far-infrared radiation devices that mainly emit light of 4 to 7 micrometers have already been put into practical use as heat sources for heating, saunas, drying, and the like.

Most of these far-infrared radiating devices control temperature, etc. through two-position operation, either during combustion or during extinguishing.However, in recent years, advanced combustion methods such as three-position control of high combustion, low combustion, and stop, or proportional control have been developed. Amount control has come to be used in some areas.

The above-mentioned far-infrared radiator has the advantage of mainly emitting light with wavelengths that are easily absorbed by water and organic substances, but on the other hand, it has low thermal efficiency because it heats excess air and exhausts it together with the exhaust gas. There are drawbacks.

Problems to be Solved by the Invention The present invention aims to increase thermal efficiency by reducing the amount of cooling air without impairing the advantage of being easily absorbed by water or air.

Measures to solve the problem In conventional far-infrared radiating equipment, when the amount of fuel is increased or decreased, the amount of combustion air is automatically increased or decreased in the same way, and the amount of cooling air is automatically increased at approximately the same rate as the amount of combustion air that is increased or decreased. It has been increasing and decreasing.

When reducing the amount of combustion, the present invention minimizes the amount of cooling air needed to keep the temperature of the combustion envelope as high as possible. In other words, we focused on the phenomenon that when reducing the amount of combustion, if the amount of cooling air is reduced in the same proportion as the amount of combustion air, the temperature of the combustion outer cylinder will be lower than during high combustion. The amount of cooling air is significantly reduced so that the temperature during low combustion is similar to that during high combustion, and the amount of cooling air during low combustion is reduced compared to before, and the amount of exhaust gas during low combustion is automatically reduced. The aim is to increase thermal efficiency.

Example Examples of the present invention will be described below.

Fig. 1 is a front view of the first embodiment of the present invention, showing a part of the piping etc. in a system diagram, and Fig. 2 is an A-A in Fig. 1.
An enlarged sectional view of the cross section, and FIG. 3 is a partially enlarged view seen from the direction of arrow B in FIG. 1.

The fuel gas is branched from passing through the governor 1, and a relatively small amount of gas passes through the orifice 2, passes through the low-burning electromagnetic piece 3, and joins with a larger amount of gas passing through the high-burning electromagnetic piece 4 from the branch, resulting in combustion. It flows into the gas burner 6 provided in the inner cylinder 5.

Combustion air enters the combustion inner cylinder 5 through the combustion air damper 7, flows into the gas burner 6 through the small hole 6-1 of the gas burner 6 as shown by the black arrow, mixes with the fuel gas, and burns.

8 is a spark rod for ignition, and 9 is an electrode rod for flame detection.

Cooling air enters the duct 11 from the cooling air damper 10, and flows into the combustion outer cylinder 12 as shown by the white arrow.
It cools both cylinders while passing between the combustion inner cylinder 5 and the combustion inner cylinder 5, gradually mixes with combustion gas downstream from the outlet of the combustion inner cylinder 5, passes through far-infrared radiation tubes 13, 14, and 15, and is discharged from the exhaust blower 16. It is exhausted to the outside from the chimney 17.

Although the above-described situation is a state of high combustion, a situation arises in which the amount of combustion must be reduced depending on the state of the object to be heated.

When a low combustion signal is output, the high combustion electromagnetic piece 4 automatically closes in the fuel gas supply line, and gas flows only through the low combustion electromagnetic piece 3 line, but the orifice 2
The amount of gas decreases due to the resistance.

In the first embodiment, the gas amount is reduced to about half that of high combustion.

At the same time, the combustion air damper 7 and cooling air damper 10, both of which are fully open, are automatically closed by the operation of the control motor 18.

At this time, as shown in Fig. 3, the combustion air damper 7
is closed by 45 degrees, but the cooling air damper 10 is closed by 60 degrees.

When the combustion air damper 7 is closed by 45 degrees, the opening area becomes about 30% of that when it is fully open (at high combustion), but since the differential pressure before and after the damper increases, in the first embodiment, the combustion air amount is reduced to 60% at high combustion. % decrease.

The opening area of the cooling air damper 10 is 13 when fully opened.
However, due to the increase in differential pressure, the amount of cooling air decreases to about 30% during high combustion.

The first embodiment described above is an attempt to improve far-infrared radiation devices already used for saunas, etc., and is one of the most commonly used devices currently in practical use. To explain with a practical example, the temperature of the combustion cylinder 12 is determined not only by the temperature of the combustion gas inside the cylinder, but also by the thickness of the combustion cylinder 12, the amount of combustion at that time, the ambient temperature, etc. The average temperature of the combustion cylinder 12 during high combustion is
The temperature is around 400℃.

The amount of combustion air during high combustion is approximately 1.2 times the theoretical air amount (air ratio 1.2, excess air ratio 20%), and the amount of cooling air is approximately 2.3 times the theoretical air amount, total air ratio 3.5 (excess air ratio 250%). ), and the amount of exhaust gas is 36N per 10,000 kilocalories of city gas whose main component is natural gas.
m is in ^3rd place.

Therefore, at low combustion, the amount of combustion air is equal to the theoretical amount of air.
1.44 times (1.2 x 0.6 x 2), cooling air volume 1.38 times (2.3
×0.3×2), which is 2.82 times the total theoretical air volume, and the combustion gas volume at this time is 29Nm per 10,000 kilocalories of city gas, which ranks ^third .

The amount of air for combustion and cooling described above will be explained.

The average temperature of the combustion cylinder 12 is 400°C as mentioned above.
In various conventional far-infrared radiating devices, it is most common that the air ratio during high combustion is set at about 3.5 and the temperature of the combustion outer cylinder 12 is set at about 400°C.

This is because if the combustion tube is made thicker, the temperature of the combustion outer tube 12 can be lowered, but if the combustion tube is made too thick, the device will become bulky. If the cylinder is too thick, there is a risk of local heating, so if you make the combustion cylinder an appropriate thickness and adjust the amount of cooling air to bring the temperature of the combustion cylinder 12 to around 400℃, the air ratio will decrease. The most common example is a rank of 3.5.

The combustion air ratio of 1.2 out of the air ratio of 3.5 is an estimated value.

The amount of combustion air during low combustion is slower than when the combustion is high, so the combustion speed must be increased, so even if the amount of combustion is reduced by 50% of that during high combustion, the amount of air is only about 60%. Therefore, the air ratio of combustion air during low combustion is 1.44.

The cooling air amount during low combustion is adjusted at the same rate as the conventional combustion air amount, so the air ratio is 60% during high combustion, and the air ratio is 2.76.
becomes.

On the other hand, in the first embodiment, it is set to 1.38, but
The numerical value was estimated as follows.

For city gas whose main component is natural gas, the theoretical combustion temperature when the air ratio is 3.5 (the temperature of the combustion gas assuming that no heat is released until combustion is completed) has a specific heat of 0.34 Kcal/Nm ³ °C. Assuming about
It becomes 735℃.

(Exhaust gas amount x specific heat x temperature = lower heating value 36 x 0.34 x temperature = 9000) Since the amount of heat generated during low combustion is 50%, the amount of heat per unit heat transfer area received by the combustion inner cylinder 5 and the combustion outer cylinder 12. is half that of high combustion.

Therefore, in order to make the surface temperature of the combustion outer cylinder 12 400° C. as in the case of high combustion, the heat transfer amount per unit heat transfer area should be doubled.

Heat transfer within the combustion chamber is mainly radiant heat transfer, and since the amount of radiant heat transfer is proportional to the fourth power of the absolute temperature, the amount of heat transfer can be increased by increasing the combustion temperature.

Now, we need to estimate at what combustion temperature the amount of heat transfer should be doubled, but since there are many factors that affect the actual combustion temperature, it is difficult to estimate, so we estimate the theoretical combustion temperature.

The amount of radiant heat transfer is affected not only by the combustion temperature but also by the temperature of the heat transfer surface (inner surface of the combustion outer cylinder 12), the radiant heat transfer coefficient, etc., but if we ignore these for the time being, the theoretical combustion temperature at low combustion is 735°C. The amount of radiant heat transfer Q is determined by the following formula, where C is a constant.

Q=C(T/100) ⁴ Q=C(273+735/100) ⁴ ...(1) When the desired temperature is T, the amount of radiant heat transfer is doubled, so the following formula holds true.

2×Q=C(T/100) ⁴ …(2) Substitute equation (1) into equation (2), 2×(1008/100) ⁴ =(T/100) ⁴ 20647=(T/100) ⁴ (T/100) ⁴ =11.99 T=11.99〓 T=926℃...(3) If the combustion temperature is raised to 926℃ as above,
It can be estimated that the amount of heat transfer will almost double and the temperature of the combustion outer cylinder 12 will be around 400°C, but it would be a problem if the estimated temperature changed significantly depending on the conditions on the heat transfer surface side. Let's consider this in more detail.

Since the temperature of the combustion cylinder 12 during low combustion in various conventional far-infrared radiating devices is often about 280°C, further estimation calculations are performed including this temperature.

The amount of radiant heat transfer between dihedra is determined by the following formula.

D [(T1/100) ⁴ - (T2/100) ⁴ ] = Q where T1; Absolute temperature of the surface of the high temperature body T2; Absolute temperature of the surface of the low temperature body D; Coefficient Amount of heat transfer during conventional low combustion Q is D [(273+735/100) ⁴ - (273+280/100) ⁴ ]=Q
...(4) The theoretical combustion temperature T3 to double the amount of heat transfer during low combustion is D [(T/100) ⁴ - (273 + 400/100) ⁴ ] = 2 x Q...
...(5) Substitute equation (4) into equation (5), D = [(T3/100) ⁴ - (6.73) ⁴ ] = 2D [(10.08) ⁴ - (5.53) ⁴ ] (T/100) ⁴ = 2 (10324-935) + 2051 (T3/100) ⁴ = 20829 T3 = 1201〓 (928℃) ... (6) As mentioned above, the temperatures in (3) and (6) are almost the same, so the theoretical combustion temperature is 900. It can be estimated that if the temperature is set to about 400°, the temperature of the combustion outer cylinder 12 will be about 400°, which is the same as during high combustion.

When the theoretical combustion temperature is 900℃, the amount of combustion gas QNm ³ for city gas (13A) whose main component is natural gas and has a calorific value of 11,000 Kcal per 1Nm ³ (lower calorific value 9000 Kcal) is the specific heat of 0.34 Kcal/ Nm ³ ℃
Then, it can be found as follows.

Q×900×0.34=9000 Q=29.4Nm ³ ...(7) It is 2.8th place.

From the above calculation results, the air amount during low combustion in the first embodiment is estimated to be 1.44 for the combustion air air ratio, 1.38 for the cooling air, and 2.82 times the total theoretical air amount.

To summarize the above, in the conventional far-infrared radiation device, 4.2 times the theoretical air amount (1.44 + 2.76) was required for low combustion to reduce the amount of combustion to 50%, but in the first embodiment of the present invention, The amount of air required was 2.82 times the theoretical amount, reducing the amount of exhaust gas and increasing thermal efficiency.

Effects of the Invention The effects of the present invention will be explained in comparison with conventional devices.

First, FIG. 6, which corresponds to FIG. 1, is shown as the most common conventional device. FIG. 7 is an enlarged sectional view taken along the line CC in FIG. 6.

As in the first embodiment, the fuel gas during high combustion is controlled by the governor 1.
A small amount of gas passing through the higher combustion orifice 2 and the low combustion solenoid valve 3 merges with a larger amount of gas from the high combustion solenoid valve 4 and flows into the gas burner 6.

Combustion air enters the combustion inner cylinder 5 through the combustion air port 19, enters the gas burner 6 as shown by the black arrow, mixes with fuel gas, and burns. The cooling air enters the duct 11 from the cooling air port 20 as shown by the white arrow, and gradually mixes with the combustion gas while cooling the combustion outer cylinder 12 and the combustion inner cylinder 5, and the combustion gas mixed with the cooling air is exposed to far infrared rays. It passes through the radiant pipes 13, 14, 15, the damper 21, the exhaust blower 16, and the chimney 1.
Exhausted from 7.

When the combustion is low, the high combustion solenoid valve 4 closes, and the amount of fuel gas is reduced by 50% when the combustion is high.The damper 21 is closed by the operation of the control motor 18, so the amount of combustion gas passing through the damper 21 is reduced to 60% when the combustion is high.
%, the amounts of combustion air from the combustion air port 19 and cooling air from the cooling air port 20 are similarly reduced to 60%.

During high combustion, the average temperature of the combustion cylinder 12 is 400°C as mentioned above, the amount of combustion air at this time is 1.2 times the theoretical air, the amount of cooling air is 2.3 times the theoretical air, and the total air ratio is 3.5 ( Excess air rate is 250%).

At low combustion, both are 60% of high combustion, so as mentioned above, the air ratio of combustion air is 1.44, the cooling air is 2.76, and the total air ratio is 4.2.

Compared to the example of the conventional device described above, the air ratio during low combustion in the first embodiment of the present invention is 2.82, and the difference (4.2-2.82=1.38) is that 1.38 times the theoretical air amount of air is heated and flows from the chimney 17. This could be prevented in the first embodiment of the present invention.

City gas whose main component is natural gas (13A)
The theoretical air amount for 10000Kcal (higher calorific value) is approximately 10N
m ³ , the first embodiment of the present invention saves 13.8 Nm ³ of air per 10,000 Kcal compared to the conventional method during low combustion. The specific heat of 0.31Kcal/Nm ³ ℃
Then, the amount of heat saved is [13.8 x 0.31 x (200-20)] 770 Kcal per 10,000 Kcal.

The low combustion exhaust gas amount of the conventional device example is:
Since it is 43Nm ³ per 10000Kcal, the specific heat of exhaust gas is
Similarly, when the temperature is 200℃, the exhaust heat loss is [43 x 0.31 x (200 - 20)] = 2399 Kcal, and the thermal efficiency (lower calorific value standard, higher calorific value 10000 Kcal)
The lower calorific value of 13A gas (9000Kcal) is 73.3%.

[(9000−2399)÷9000]×100=73.3% The exhaust loss during low combustion in the first embodiment of the present invention is
Since it is 1629Kcal, the thermal efficiency is 81.9%, 2399-770=1629 [(9000-1629) ÷ 9000] x 100 = 81.9% At low combustion, fuel can be saved by 10.4% compared to the conventional model.

[(9000-2399) ÷ (9000-1629)] x 100 = 89.6 100-89.6 = 10.4% How effective is a 10.4% fuel saving during low combustion when the device is operated continuously? Consider.

High combustion time is H, low combustion time is L,
The combustion amount of high combustion is q, the total combustion amount of conventional equipment is Q1,
Letting the total combustion amount of the first embodiment of the present invention be Q2, the fuel saving rate can be calculated as follows.

H x q + L x 0.5q = Q1 ... (1) H x q + L x 0.5q (1 - 0.104) = Q2 ... (2) (2) ÷ (1) H x q + L x 0.5q (1 - 0.104) / H×q+L×0.5q
=Q2/Q1 H+0.448L/H+0.5L=Q2/Q1...(3) The ratio of high combustion and low combustion operating time differs for each device, but in general, combustion occurs at high combustion when starting,
After the temperature rises to the specified temperature, low combustion operation often occurs. Therefore, most continuous dryers such as sauna heat sources, far infrared ray radiators, and conveyor dryers that operate continuously for long periods of time operate at low combustion levels. Intermittent operation equipment is less effective.

Many commercial saunas are open for 16 hours a day, and in commercial saunas that operate equipment for an average of 16 hours a day, the startup time is about 30 minutes to 1 hour throughout the year. Assuming that the combustion time is 12 hours and the combustion stop time is 2 hours (as this is assumed to be the most common example), from equation (3), the device of the present invention achieves 91.0% of the conventional device.
of heat can save up to 9% of fuel.

If a heating system is operated for 10 hours a day, and assumes that the high combustion time is 1 hour a day, the low combustion time is 8 hours, and the combustion stop time is 1 hour throughout the season, 8.3% of fuel can be saved.

Even highly effective devices have an energy saving effect of less than 10%, but the thermal efficiency of modern combustion devices is already quite high, so when used in saunas and heating devices, the device of the present invention is a simple improvement of the device. can have a great effect.

The present invention is applicable not only to the first embodiment described above, but also to an apparatus that generates far infrared rays by heat of combustion of fuel, when cooling air is flowed outside the combustion chamber to reduce the amount of combustion, the amount of combustion air is automatically reduced. Various design changes are possible within the range of the characteristic that the rate of decrease in the amount of cooling air is made larger than the rate of decrease in the amount of cooling air.

For example, FIG. 4 shows the second embodiment of the present invention, and the combustion amount control in the first embodiment is a three-position control of high combustion, low combustion, and stop, but the second embodiment is a more advanced proportional control. This is an example of the method.

The combustion amount gas amount is proportionally adjusted by a butterfly valve 22 that is linked to a control motor 18.
When the control motor 18 and butterfly valve 22 operate at a maximum of 60 degrees, the combustion air damper 7 operates at a maximum of 45 degrees, and the cooling air damper 10 operates at a maximum of 60 degrees, so that the rate of decrease in air volume is always greater for cooling air. There is.

FIG. 5 is an enlarged view of the burner portion of the third embodiment of the present invention. The gas burner of the first embodiment was a pre-mixing type gas burner, but the third embodiment is equipped with a pre-mixing type gas burner.

Approximately 50 to 70% of the theoretical air amount during high combustion passes through the combustion air damper 7 and enters the mixing tube 23, mixes with the fuel gas, flows out from the flame port 24 into the combustion inner cylinder 5, and passes through the cooling air damper 10. A part of the air that has flowed into the duct 11 through the secondary air port 25 flows through the secondary air port 25 and is mixed and burned as secondary air, but the amount of secondary air at this time is about 50 to 70% of the theoretical air amount. The amount of cooling air passing between the combustion inner cylinder 5 and the combustion outer cylinder 12 is the theoretical air amount.
The amount of air passing through the cooling air damper 10 is about 2.8 to 3 times the theoretical amount of air.

During low combustion, where the combustion amount is reduced to 50%, the combustion air damper 7 closes only a little, so air at about 90 to 110% of the theoretical air amount is used as primary air in the mixing tube 2.
3, about 1.6 to 1.8 times the theoretical air amount enters from the cooling air damper 10, of which 20
%, that is, about 35% of the theoretical air amount, is supplied from the secondary air port 25 into the combustion inner cylinder 5 as secondary air for combustion.

In addition, the burner should be changed to a hydraulic spray oil burner, etc., and the fuel should be changed to liquid fuel.

The combustion inner cylinder 5 is manufactured using punched metal, porous ceramic, etc., and light from the combustion flame is radiated to the inner surface of the combustion outer cylinder 12 through the holes, increasing the amount of heat transfer in the upstream part of the combustion outer cylinder 12. to let

The length of the combustion inner cylinder 5 is shortened, the tip of the combustion flame is exposed inside the combustion outer cylinder 12, and the radiant heat is radiated from the flame tip to the combustion outer cylinder 12.
increasing the amount of far-infrared radiation emitted from the

etc.

[Brief explanation of the drawing]

FIG. 1 is a front view of the first embodiment of the present invention, showing a part of the piping diagram as a system diagram. 2 is an enlarged cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a partially enlarged view taken from the direction B in FIG. FIG. 4 is a diagram for explaining the control form of the second embodiment of the present invention, and FIG. 5 is an enlarged sectional view of the burner portion of the third embodiment of the present invention. FIG. 6 is a diagram corresponding to FIG. 1 of the conventional device example, and FIG. 7 is a sectional view taken along the line CC in FIG. 4. 1... Governor, 2... Orifice, 3... Low combustion solenoid valve, 4... High combustion solenoid valve, 5... Combustion inner cylinder, 6... Gas burner, 7... Combustion air damper, 8... For ignition Spark rod, 9... Electromagnetic rod for flame detection, 10... Cooling air damper, 11... Duct, 12... Combustion cylinder, 13, 14, 15...
Far-infrared radiation tube, 16... Exhaust blower, 17...
...Chimney, 18...Control motor, 22...
Butterfly valve, 23...mixing pipe, 24...flame port,
25...Secondary air port.

Claims (1)

[Claims] 1 Burning gas or liquid fuel in the pipe or circulating combustion gas in the pipe and emitting infrared rays from the outside of the pipe to heat the human body, objects, etc., and use it as a heat source for heating, saunas, and various dryers. A tubular inner cylinder is provided in the combustion tube that burns the fuel of the infrared radiation device to be used, and the inside of the combustion tube inner cylinder is used as a combustion chamber in which the fuel is burned, and cooling air is provided between the outer surface of the combustion tube inner cylinder and the inner surface of the combustion tube. In a far-infrared radiating device, the combustion air used mainly for combustion is used to maintain the outer surface of the combustion tube at approximately 500°C or less by circulating air, and the generated infrared rays are mainly far-infrared rays with longer wavelengths. A mechanism is provided to separately and automatically adjust the amount of cooling air mainly used for cooling the combustion tube and the combustion tube inner cylinder, and the amount of fuel supplied, and the amount of fuel supplied and the amount of air are adjusted. The ratio of the combustion air amount to the cooling air amount, that is, the value obtained by dividing the combustion air amount by the cooling air amount, is smaller when the combustion amount is large than when the combustion amount is small, and when the combustion amount is small compared to when the combustion amount is large. A method for controlling the combustion amount and air amount of a far infrared radiating device, characterized in that the amount of combustion and air amount of a far infrared radiating device is automatically operated so as to increase the amount of infrared rays.