JPH01296048A - Liquid tank heating device - Google Patents

Abstract

PURPOSE:To facilitate the maintenance by employing a sealed structure immersible in a liquid for a burning apparatus to which a mixture of fuel and oxidizing substance such as air is supplied, a combustion catalyst being disposed inside the sealed structure and a combustion section served by the combustion catalyst being disposed in the liquid with a heat insulating material interposed between the combustion catalyst and the inner surface of the casing. CONSTITUTION:The device has a fuel gas nozzle 7 to supply fuel gas 9 and a combustion air nozzle 8 to supply combustion air 10, and these nozzles are connected to a mixed gas supply pipe 41. The device is completely immersed in a liquid 2 in a liquid tank 1. A combustion section 5 comprising a combustion catalyst 27 is suspended from the top flange of the body casing 26. Between the top flange of the body casing 26 and the combustion catalyst 27, a heat insulating material 30 is set to accomplish the heat insulation as well as the sealing of mixed gas 28. The structure assures that the combustion catalyst 27 is not directly cooled by the liquid 2 in the tank and the body casing 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid tank heating device for heating a fluid in a liquid tank.

[Conventional technology]

Conventionally, methods shown in FIGS. 12 and 13 have been used to heat cleaning liquids and chemical liquids in degreasing tanks and the like in pretreatment steps for painting and plating, and to heat plating liquids in plating tanks. Fig. 12 shows a method in which a heat transfer tube 6 is arranged in a liquid tank l, and steam 47 is passed through the heat transfer tube 6 to heat the liquid 2 in the liquid tank.This method is used in factories equipped with boiler equipment, etc. is the mainstream.

However, in this method, in order to heat the liquid 2 in the liquid tank, it is necessary to operate the boiler and generate steam regardless of the amount used. Since it was necessary to heat the liquid 2 in the liquid tank before factory operation, it was necessary to operate the boiler to a steady state by early discharge.

Figure 13 shows a factory without a boiler or a system that uses a heating source instead of steam.As shown in the figure, the liquid tank 1
An electric heater 3 such as an electric sheathed heater is placed inside the tank to heat the liquid 2 in the tank and maintain its temperature. This method is capable of heating the liquid 2 in one liquid tank by throwing it into the liquid tank 1 without installing the electric heater 3 in the liquid tank 1. It is widely used as a simple method because it can be completely immersed in water. However, the power connection part of the electric heater 3 is connected to the liquid 2 in the liquid tank.
It is not very suitable for heating a large, large-capacity liquid tank because it uses an electric heater 3, and the operating cost is high because it uses electricity as a heating source. In recent years, combustion type heaters using gas fuel or the like have come into use. Typical combustion type heaters are shown in FIGS. 14 to 16.

Fig. 14 shows a heater used in a relatively small liquid tank, Fig. 15 shows a heater used in a large capacity liquid tank, and Fig. 16 shows a heater used in a relatively small liquid tank. An example of the structure of a burner combustion part in the heater shown in the figure is shown. FIG. 14 shows an immersion type which does not require special attachment to the liquid tank, and FIG. 15 shows a liquid tank mounting type using a liquid tank mounting flange 12.

In both FIGS. 14 and 15, the combustion type heater 4 consists of a burner combustion section 5 and a heat transfer tube 6. In this combustion type heater, fuel gas 9 is supplied from the fuel gas nozzle 7, and burner combustion air 10 is supplied from the combustion air nozzle 8 to the burner combustion section 5. They are combusted in the burner combustion section 5, and the high-temperature combustion exhaust gas 11 It passes through a heat transfer tube 6 disposed in the liquid tank 1, exchanges heat with the liquid 2 in the liquid tank, heats the liquid 2 in the liquid tank, and then is exhausted as a low-temperature combustion exhaust gas 11.

In addition, the burner combustion section 5 has, as an example shown in FIG. 16,
It consists of a fuel gas nozzle 7, a combustion air nozzle 8, a burner nozzle 13 attached to the tip of the fuel gas nozzle 7, a flame stabilizer 16, a spark plug 14, and a flame rod 15. The fuel gas 9 introduced from the fuel gas nozzle 7 is supplied into the burner combustion section 5 through the fuel gas jet hole 17 provided in the burner nozzle 13 attached to the tip of the fuel gas nozzle 7, and is introduced from the combustion air nozzle 8. The spark plug 14 is mixed with the combustion air 10 and ignites and burns using the electric spark of the spark plug 14 as a heat source.The spark plug 14 stops the spark after ignition and combustion is confirmed by the flame rod 15.After ignition, the flame stabilizer 16 This stabilizes the combustion flame,
Burns continuously. Further, the flame rod 15 monitors for loss of height after continued combustion.The combustion exhaust gas 11 passes through the burner combustion section 5 and is introduced into the heat transfer tube 6 attached to the outlet of the burner combustion section 5.

This combustion type heater consists of a combustion gas 11 and a liquid 2 in a liquid tank.
Since direct heat exchange is performed through the heat transfer tube 6, the thermal efficiency is relatively high, and since it is a direct combustion method of fuel gas, the operating cost is lower than the above-mentioned electric heater method, which is an advantageous method. It is. However, since combustion occurs by forming a flame, when the flame comes into contact with the wall surface of the main body of the burner combustion part 5 immersed in the liquid 2 in the liquid tank, the flame is cooled and incomplete combustion occurs, causing combustion gas to be mixed in. There is a problem in that the exhaust gas contains unburned gases such as carbon monoxide (CO) and fuel gas components (hydrocarbons such as CH and C*Hs). Therefore, as shown in FIGS. 14 and 15, the burner combustion section 5 is connected to the liquid 2 in the liquid tank.
must be placed above the liquid level or outside the liquid tank l.

Regarding the injection type shown in Fig. 14, the burner combustion part 5 is arranged above the liquid level of the liquid 2 in the liquid tank, but in plating tanks, cleaning tanks, etc., products or semi-finished products are transferred to the liquid tank. In many cases, the space to be transported is above the liquid tank, which causes deterioration of workability, etc. Therefore, as shown in Fig. 15, a method of mounting by fixing it to the side of the liquid tank l with a liquid tank mounting flange 12, etc. However, in this case, in order to install the heater, it is necessary to provide two holes in the liquid tank 1, one for inserting the burner combustion part 5 and the other for exhaust, and the processing and construction of the liquid tank 1 are required for this purpose. It is also inconvenient that the liquid 2 in the liquid tank must be removed during maintenance of the heater 4. In addition, the main body of the combustion section 5 is located above the level of the liquid 2 in the liquid tank, or
The combustion section 5 has the highest temperature because it is located outside of the
The heat dissipated from the main body is not effectively used to heat the liquid 2 in the liquid tank and becomes lost heat, which is negative in terms of thermal efficiency.

[Problem to be solved by the invention]

In the conventional combustion type liquid tank heater described above, in order to prevent incomplete combustion due to flame cooling, the combustion part must be placed in a space above the liquid level in the liquid tank or outside the liquid tank. The immersion type had problems such as obstructing the transportation path for the product immersed in the liquid tank. On the other hand, in order to solve rJIm, a combustion type liquid tank heater that is fixedly mounted on the side of the liquid tank so as not to interfere with the product transportation path requires processing or modification of the liquid tank when installing it. There were problems such as the need for time-consuming maintenance of the heater and the fear of liquid leakage from the mounting part. There is also the problem that heat radiation from the combustion section cannot be effectively used to heat the liquid.

The purpose of the present invention is to solve the above-mentioned problems of the prior art, and to provide a liquid tank that can be used regardless of the liquid tank capacity and that can reduce operating costs. It is an object of the present invention to provide a liquid tank heating device that can be placed inside a liquid tank and can be of an immersion type that can be easily maintained.

[Means to solve the problem]

The above purpose is to provide a combustion device to which a mixture of fuel and an oxidizing agent such as air is supplied, with a sealed structure that can be immersed in a liquid, and to install a combustion catalyst inside the combustion device, so that combustion by the combustion catalyst in the liquid is carried out. This is achieved by forming a section and interposing a heat insulating material between the combustion catalyst and the inner peripheral surface of the container.

[Effect]

In catalytic combustion using a combustion catalyst, the catalyst components pa and p
Due to the oxidation promoting effect of noble metal elements such as T and PH or non-metal elements such as Cu and Ni, fuel gas and oxygen (air etc.) are catalytically burned on the surface of the catalyst.

Therefore, compared to normal flame combustion (burner combustion), the combustion speed is significantly faster, and complete oxidation and combustion are possible at low temperatures.Combustion is completed within the combustion catalyst block, and no flame is generated. If the catalytic combustion unit body containing the combustion catalyst block has a sealed structure that prevents leakage of liquid, etc., even if immersed in low-temperature liquid, the flame will come into contact with the cooled wall of the combustion unit body, as in the case of flame combustion. By insulating only the support portion where the combustion catalyst block contacts the wall surface with a heat insulating material, complete combustion without any unburned matter is possible.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

An embodiment of the liquid tank heating device according to the present invention is shown in FIGS. 1 to 5. FIG. 1 is an overall view showing an example of the installation of the liquid tank heating device according to the present invention in a liquid tank. is a detailed structure diagram showing the structure of the liquid tank heater in Figure 1, and Figure 3 is A- in Figure 2.
AAI sectional view, FIG. 4 is a sectional view corresponding to the line A-A in FIG. 2 in the case of large capacity.

Further, FIG. 5 shows an example of the system of the liquid tank heating device according to the present invention.

This device has a fuel gas nozzle 7 that supplies fuel gas 9 and a combustion air nozzle 8 that supplies combustion air 10.
These nozzles are connected to a mixed gas supply pipe 41. This mixed gas supply pipe 4 is connected to a mixed gas nozzle 25 provided on the heater main body 4. A combustion catalyst 27 is disposed within the main body casing 26 of the heater main body 4, and a heat transfer tube 6 is connected thereto. As shown in FIG. 2, in the heater main body 4, the opening of the mixed gas nozzle 25 inserted from one end in the axial direction of the cylindrical main body casing 26 is located at the center of the casing, and the combustion catalyst 27 is located at the center of the casing. It is installed on the outer periphery. Combustion catalyst 2
As shown in FIG. 3, a large number of tubes 7 are connected via a heat insulating material 30 and formed into a cylindrical shape.

In addition, a main body casing 26 and a combustion catalyst 2 are included for radioactive activation.
A spark plug 14 is installed between the spark plug 7 and the spark plug 7.

Next, the operation of the liquid tank heating device configured as described above will be explained.

The liquid tank heating device according to the present invention is used in a state where it is completely immersed in the liquid 2 in the liquid tank 1, as shown in FIG.

In this case, if the burner combustion (gas phase combustion) method is used, the main body casing 26 itself, which is submerged in the liquid, is cooled from the outer periphery by the liquid 2 in the liquid tank, and when it comes into contact with the flame, the flame is cooled and unburned components There is a problem that harmful gases are generated. However, as in the embodiment, there is no combustion catalyst 2 in the combustion section 5.
7, and the combustion section 5 constituted by the combustion catalyst 27 is suspended from the flange of the ceiling of the main body casing 26, so that the side wall of the main body casing 26 and the combustion catalyst 27 are cooled by the liquid 2 in the liquid tank. The combustion part 5 is made independent from the main casing 26 by providing a gap 27 between it and the combustion gas outflow surface of the combustion catalyst 27. can be burned at high temperatures without flame without being cooled. Therefore, a heat insulating material 30 that also serves as a seal for the mixed gas 28 is provided between the combustion catalyst 27 and the ceiling flange portion where the combustion catalyst 27 and the main casing 26 come into contact.
It can be sandwiched and insulated.

As shown in FIG. 2, the combustion catalyst 27 and the main body casing 26
The only contact part is the ceiling part of the main body casing 26 (the ceiling part has a flange structure, so that the combustion catalyst 27 can be taken out from the main body casing 26), and the contact part also serves as a seal. The structure is such that the direct combustion catalyst 27 itself is not cooled by the liquid 2 in the liquid tank or the main body casing 26.

Similarly, as shown in FIGS. 3 and 4, the joint of the combustion catalyst 27 and the gap between it and the catalyst support 42 are also filled with a heat insulating material 30 that also serves as a seal. In the present invention, a honeycomb-shaped combustion catalyst is preferably used as the combustion catalyst 27. The honeycomb-shaped combustion catalyst is made by supporting a catalyst component and an alumina material having a high-pressure surface area on a base material formed of ceramic such as cordierite into a honeycomb shape. ℃, and the combustion catalyst 27 emits solid radiant heat. Since the combustion catalyst 27 is arranged over the entire circumference of the main casing 26, the radiant heat from the combustion catalyst 27 is absorbed over the entire area of the main casing 26. The heat absorbed is effectively transferred from the main body casing 26 to the liquid 2 in the liquid tank, and no heat loss occurs due to heat radiation. In experiments, the effective heat of the entire heater can be ensured to be 90% or more of the total input heat (thermal efficiency) by adjusting the length of the heat transfer tube. (This is all heat given to the liquid 2 in the liquid tank.) Of the 90% or more of the effective heat, 60% or more is the heat transferred from the combustion section 5, that is, the main body casing 26. It was found that the main body casing 26 effectively acts as a heat transfer surface for heating the liquid 2 in the liquid tank. Therefore, the length of the heat exchanger tube can be reduced to about 1/3 compared to the conventional method. In addition, the heater according to the present invention has only the fuel pipe 7, the combustion air pipe 8, or the mixed gas pipe 41, and the exhaust port of the heat transfer pipe 6 on the upper open surface of the liquid tank l, occupying a large space. Since the combustion part 5 is located in the liquid tank 2, there is an advantage that the overhead space of the liquid tank 1 can be used effectively without hindering the transportation of products, etc.
Since the heater is an immersion type heater and can stand on its own at the bottom of the liquid tank 1, there is no need to modify the liquid tank 1 for installation.
It also has the advantage of being easy to construct and easy to maintain.

Next, the operating procedure of the heating device of the present invention will be explained based on FIG. 5.

When the operation switch 33 is first turned on during operation, the air fan 32 is activated and the combustion air 10 is supplied to the catalyst layer in the liquid tank heater.

At that time, a fuel solenoid valve 38A disposed in the flow path of the fuel 9,
38B and the air solenoid valves 39A and 39B are both closed. Combustion air is supplied in a minimum amount (MI Ni1).

When the air pressure reaches a set pressure by the pressure switch 46 installed in the combustion air lOO flow path, the ignition plug 14 starts sparking via the ignition device 34. At the same time, the fuel solenoid valve 38A and the air solenoid valve 39B are opened, and the combustion section 5
A mixed gas 28 of fuel 9 and combustion air 1O is supplied to the combustion catalyst 27 inside through the mixed gas nozzle 25. As shown in FIG. 2, the mixed gas 28 is supplied from the tip of the mixed gas nozzle 25, passes in the circumferential direction of the cylindrical combustion catalyst 27, and is ignited by the spark of the ignition plug 14 at the outlet of the combustion catalyst 27. A short flame plug is formed on the surface of the combustion catalyst 27 and combustion occurs. (Hereinafter, this will be referred to as surface combustion.) By this surface combustion, the combustion catalyst 27 is preheated to the catalytic combustion ignition temperature, and heating of the liquid 2 in the liquid tank is started. The conditions for this surface combustion are an air ratio of 1.05 to 1.7, and a surface load of 10XIO' to 20XI with respect to the outer surface area of the catalyst.
The preheating temperature of the combustion catalyst 27 varies depending on the fuel type, but it is approximately O'kcal/m'' h.
For CH4) type fuel, the temperature is 600°C to 800°C, and the preheating time is 1 minute to 10 minutes. During this preheating time, that is, the surface combustion time, combustion gradually shifts to catalytic combustion, and the preheating time is set in the timer 35.

It goes without saying that when igniting, instead of igniting the surface combustion directly from the spark plug 14, it is possible to ignite the surface combustion via the pilot burner.

When the timer 35 is up, the air solenoid valve 39A is closed, while the air solenoid valve 39B is opened, and combustion on the high load side of catalytic combustion begins.

The conditions are: air ratio 1.6 to 2.5, surface load 10X10
'~10X10'kcal/m'' h.

The liquid temperature is adjusted by a liquid temperature controller 45, and when the liquid temperature exceeds the set value, the fuel solenoid valve 38A is closed, the fuel solenoid valve 38B is opened, and the air solenoid valve 39B is closed, and combustion is started. The minimum amount (MIN amount) of the air 10 is supplied,
Switch to combustion on the low load side of catalytic combustion. The conditions at this time were an air ratio of 1°1 to 2.0, and a surface load of 5Xl.
O' to 10XIO'kcal/m''h, and the turndown between high-load combustion and low-load combustion is preferably 1/2 to 1/4.

This high-load combustion and low-load combustion are repeated in response to instructions from the liquid temperature controller 45 to adjust the liquid temperature within a constant value. In this embodiment, an example of two-stage switching is shown, but it is also possible to control multiple stages beyond two stages and 0N-OFFIQ of combustion.
It goes without saying that ml is possible.

As a safety device, the temperature switch 37B detects backfire due to an abnormally high temperature on the mixed gas inlet side of the combustion catalyst 27, and confirms ignition of surface combustion due to an abnormally low temperature on the exhaust gas outlet side of the combustion catalyst 27 and catalytic combustion. Misfire and combustion catalyst 26
It is enough to detect the deterioration of the temperature switch 37A using the temperature switch 37A.

6 to 8 show other embodiments of the present invention, FIG. 6 is an overall configuration diagram thereof, FIG. 7 is a detailed structural diagram of the liquid tank heater in FIG. 6, and FIG. It is a sectional view taken along the line BB in the figure.

This liquid tank heating device is divided into two regions, upper and lower, by a combustion catalyst 27 disposed horizontally within a cylindrical main body casing 26 having a short cross-section. A rectifier plate 29 is provided below the mixed gas nozzle 25 located above the combustion catalyst 27, and the area within the casing below the combustion catalyst 27 is covered with a plurality of fuel gas nozzles 6 arranged at predetermined intervals in the longitudinal direction of the main casing 26. It communicates with the opening.

9 to 11 show still other embodiments of the present invention, FIG. 9 is an overall configuration diagram thereof, FIG. 10 is a detailed structural diagram of the liquid tank heater in FIG. 9, and FIG. FIG. 9 is a sectional view taken along line CC in FIG. 9;

This liquid tank heating device is divided into two regions, left and right, by a combustion catalyst 27 arranged vertically inside a cylindrical main body casing 26 with a short cross-section, and the tip opening of the mixed gas nozzle 25 is located in the middle of one region. It is located in the department. In addition,
40 in FIGS. 6 and 9 indicates an exhaust gas header.

In the liquid tank heating device shown in FIGS. 6 to 11, in addition to the effects of the embodiment shown in FIG. can. Therefore, the width of the body casing 26 is made thinner so that the liquid tank heater can be placed close to the bottom or side wall of the liquid tank 1, and the space inside the liquid tank 1 can be used more effectively.
In addition, by increasing the planar area, it becomes possible to make the device larger.

〔Effect of the invention〕

According to the present invention, the liquid tank is heated in the liquid in the liquid tank.
Since the tank (combustion section) can be completely immersed, it is possible to eliminate heat radiation loss from the high temperature part of the combustion section, which has the effect of improving thermal efficiency. By eliminating this, work efficiency such as transportation of products is improved. In addition, since the heater can be used as an immersion type, there is no need to modify the liquid tank, making maintenance easier.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a liquid tank heating device showing an embodiment of the present invention, Fig. 2 is a detailed structural diagram of the liquid tank heater in Fig. 1, and Fig. 3 is a line A-A in Fig. 2. 4 is a cross-sectional view corresponding to the A-A line in FIG. 2 for a large-capacity type, FIG. 5 is a system diagram of the liquid tank heating device according to the present invention, and FIG. 6 is another embodiment of the present invention. FIG. 7 is a detailed structural diagram of the liquid tank heater in FIG. 6, FIG. 8 is a sectional view taken along line B-B in FIG. 7, and FIG. 9 is a diagram showing still another embodiment of the present invention. Overall diagram showing examples,
Fig. 10 is a detailed structural diagram of the liquid tank heater in Fig. 9, Fig. 11 is a sectional view taken along the line C-C in Fig. 10, and Figs. 12, 13, 14, and 15 are respectively conventional An overall configuration diagram showing the liquid tank heating device, Figure 16 is similar to Figure 14 and Figure 1.
6 is a detailed structural diagram of the liquid tank heater in FIG. 5. FIG. 1...Liquid tank, 2...Liquid in the liquid tank, 4.
...Liquid tank heater, 5...Combustion section, 6
... Heat exchanger tube, 14 ... Spark plug, 2
5...Mixed gas nozzle, 26...Body casing, 27...Combustion catalyst, 28...
...mixed gas, 29... rectifier plate, 30...
...Insulation material, 33...Operation switch, 34...
...Ignition device, 35...Timer, 36.
...-Transformer, 37A, 37B...Temperature switch, 38A, 38B...Fuel solenoid valve, 3
9A, 39B...Air solenoid valve, 40...
・Rudder to exhaust gas, 43A, 43B... Fuel adjustment valve, 44A, 44B, 44C... Air adjustment valve, 45... Liquid temperature regulator, 46... ··pressure switch. Agent Patent Attorney Masaru Nishimoto - Figure 14

Claims (7)

[Claims] (1) A supply pipe for fuel and air, etc., an oxidizer, a combustion device that burns the mixture of fuel and oxidizer from this supply pipe, and a liquid tank into which combustion exhaust gas from the combustion device is introduced. In the liquid tank heating device, the combustion device is equipped with a heat transfer part such as a heat transfer tube immersed in the liquid in the liquid tank, and heats the liquid in the liquid tank by heat exchange between combustion exhaust gas and the liquid. A liquid that has a closed container structure that can be immersed in the container, a combustion catalyst is installed inside the container at a distance from the inner peripheral surface of the container, and a heat insulating material is interposed between the closed container and the combustion catalyst. Tank heating device. (2) The liquid tank heating device according to claim 1, wherein the combustion device has a structure in which the combustion exhaust gas generated by the combustion catalyst flows through an inner wall surface of a casing of the device body. (3) The combustion device has a main body casing formed in a cylindrical shape, a cylindrical combustion catalyst arranged concentrically with the casing inside the casing, and an opening of a mixed gas nozzle located inside the combustion catalyst. The liquid tank heating device according to claim 1, characterized in that: (4) In the heating device, the main body casing of the device consists of a cylinder with a rectangular cross section, and a plate-shaped combustion catalyst is disposed inside the cylinder, dividing the cylinder into two regions, and one region contains mixture. 2. The liquid tank heating device according to claim 1, wherein an opening of a gas nozzle is located. (5) The liquid tank heating device according to claim 4, wherein a rectifying plate is installed in a region where the opening of the mixed gas nozzle is located. (6) In the combustion device, an ignition means for preheating the combustion catalyst at startup, a timer for setting the preheating time necessary for transitioning from low-load combustion to high-load combustion, and preheating by this timer. 2. The liquid tank heating device according to claim 1, further comprising means for controlling the supply amount of fuel and air so that the air ratio necessary for high-load combustion is achieved after a period of time has elapsed. (7) A means for installing a liquid temperature detector in the liquid tank and controlling the amount of fuel and air supplied to the combustion catalyst based on the detected liquid temperature value to switch from low-load combustion to high-load combustion. 2. The liquid tank heating device according to claim 1, further comprising: