JPS6042588A - Plate - 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 According to the present invention, a shelf used for heating, drying, sterilization, etc. is surface-treated with metal oxides, nitrides, borides, sulfides, carbides, etc. The shelves used in conventional heat medium circulation tray dryers are made of bare metal materials such as iron and stainless steel, and transfer thermal energy to the heated object through heat transfer, convection, and radiation. However, all three types of heat transfer apply heat from outside the object to be heated.
This is an external heating heat transfer type that transfers thermal energy internally through thermal conduction. This results in a difference between the surface temperature and the center temperature of the object to be heated, resulting in uneven heating and uneven drying. Measures to avoid this uneven heating and drying include increasing the temperature of the circulating heating medium to a relatively high temperature or increasing the heating time, but these are not efficient solutions. . Depending on the object to be heated, high temperatures cannot be applied, and if drying takes a long time, quality problems may occur. This is attributable to the fact that conventional shelves are of the external heating type for heat transfer to objects to be heated.

There are three methods for internal heating and heat transfer in which the heated object itself generates heat: microwave, high frequency, and infrared rays, but the present invention uses infrared rays, which has significantly lower running costs and initial costs than the other two methods. It belongs to internal heating heat transfer method.

Generally, polymeric substances (water,
Food, wood, oil, fat, resin, etc.) are chemically bonded while their molecules influence each other (molecular vibrations) at a certain frequency. When irradiated with infrared rays having a wavelength that matches the molecular vibration frequency of this polymeric material, the molecular vibrations of the polymeric material are doubled. This phenomenon generates intense frictional heat between each molecule, causing self-heating within the substance itself. This is the theory of internal heat generation of substances due to infrared irradiation, but the wavelength range of infrared rays is from 0.75 μ to 10
00μ, which wavelength range is
It is important whether the wavelength matches the vibrational wavelength of the polymer material. This is experimentally said to be in the wavelength range of 5μ to 50μ. However, the wavelength of electromagnetic waves emitted from traditionally used infrared lamps and quartz tubes is 3.
μ or less, and for this reason, a considerable amount of the electrical energy emitted from conventional infrared lamps passes through the material, and only a radiant heat effect (external heating effect) can be expected as a heat ray. Even though it is called infrared heating, it is an external heating heat transfer method that is not much different from other methods.

Since the wavelength range of infrared rays is too wide, for convenience we have divided it into near infrared rays (0.75 to 1.5μ), mid-infrared rays (1.
．． 5μ~5.6μ), far infrared rays (5.6~1000μ)
This means that the irradiation wavelength from conventional infrared lamps is in the region below mid-infrared rays, and the wavelength of 5μ to 50μ, which matches the vibrational wavelength of polymeric substances, is in the far-infrared region. Recognize.

Recently, far-infrared rays have been actively researched and developed, and among them, there is a particular focus on radiant heating elements that emit wavelengths of 3μ to 100μ to promote internal self-heating of polymeric materials that are heated. Development is active. In this method of manufacturing a far-infrared radiation heating element, a resistance heating element such as a nichrome wire is embedded in a metal pipe so that it does not come into contact with the outer wall through an insulating material. The outer surface of the metal pipe is baked with metal oxides, etc., such as titanium oxide and zirconia-based radiation materials, which emit electromagnetic waves in the far infrared region of about 3μ to 100μ when heated. be.

As mentioned above, the advantage of this nichrome wire far-infrared radiator is that it promotes self-heating from within the heated object, but when actually using this nichrome wire radiator, there are several It can be seen that it has important drawbacks.

The major drawback (1) is that the radiation wavelength that can cause internal heat generation in a substance is generally controlled by measuring the outer surface temperature of a far-infrared radiator, converting it into a wavelength, and controlling it accordingly. However, in this case, it is much more difficult to measure and control the outer surface temperature than with the hot air method.

(2) Since far infrared rays are radiant heat similar to sunlight, unless the object to be heated is directly irradiated with far infrared rays, the heating effect will be halved. Therefore, it may be necessary to turn over the object to be heated during heating, or to place the object on a rotary table and heat it while rotating the object.

When (3) is used for heating in a furnace, the nichrome wire and the wiring inside the furnace to the temperature sensor must be heat-resistant, and in some cases, it may not be possible to use it.

(4) Most of the nichrome wire far-infrared radiators currently on the market have almost the same external shape as rod-shaped fluorescent tubes commonly used as lighting equipment. Because of this shape, a reflecting mirror is always attached for the purpose of focusing the heat rays on the object to be heated. Furthermore, since it comes with bracket legs for fixed mounting, the height of the heating element is at least 50 mm or more, and when actually using the nichrome wire rod tube, it is necessary to irradiate the heated object with as much energy as possible. For the purpose of uniformity,
It is said that there must be a distance of at least 150 mm between the surface of the heating element and the top of the object to be heated. (If you get closer than this, it will be difficult to measure the temperature mentioned in (1), and you will also be more likely to get partially overheated, that is, burnt.) In this case, the nichrome wire far-infrared radiator
The dead space is so large that it cannot be used as a heat source for tray drying, which is commonly used, due to its poor volumetric efficiency.

(5) Far infrared rays emit invisible light, so they cannot normally be seen with the naked eye, and the temperature is relatively low, so even if the nichrome wire is broken, it cannot be easily seen. (It would be possible to check which heater has broken if the wire was connected to each heater one by one, but this is not practical.) Infrared emitters have serious drawbacks. Overcoming all the drawbacks of 2, and
The present invention (
(shelf shelves whose surface has been treated with metal oxide, etc.).

Metal oxides such as titanium oxide are baked on the surface of the shelves that circulate heat medium (steam, water, hot water, hot water, oil, etc.), which is often used in dryers, etc., and the heat medium that circulates internally is used. Then, when the shelf is heated, if it emits electromagnetic waves in the far-infrared region, this shelf is already an excellent far-infrared radiating heating element. This can be called a ``thermal medium circulation tray type far-infrared radiant heating element'' in contrast to the name nichrome wire type far-infrared radiating heating element.

This "heating medium circulation tray type far-infrared radiation heating element" solves all the drawbacks of the above-mentioned nichrome wire heating element at once. Each will be explained individually below.

The problem of temperature measurement in (1) is that if the heating medium circulation type tray is used, the heating medium in the tray inside the furnace is circulated outside the furnace, so it can be measured at a convenient location outside the furnace. It is sufficient to measure the temperature of the circulating heat medium. (2) The area in the shadow of the irradiation is not heated because the conventional nichrome wire heating element is a rod-shaped tube. In the tiered type of the present invention, electromagnetic waves (heat rays) are radiated over the entire surface from the plate-like surface, so there are no shadowed areas. (3) The nichrome wire inside the furnace and the wiring to the temperature measuring element on the surface are not required at all in the heating medium circulating type shelf type far infrared radiating heating element according to the present invention. (4) Regarding the problem of the dead space of the nichrome wire type, with the present invention, radiation is emitted from the entire surface, and there is no need for a reflecting mirror, and of course there is no need for a bracket for mounting the reflecting mirror. ,
Since the distribution of radiant energy is uniform, burnout is unlikely to occur, and unlike the case of nichrome wire tubes, the narrower the distance between the shelf and the heated object, the better the efficiency. (
The energy radiation efficiency is inversely proportional to the square of the distance. This improves the volumetric efficiency to such an extent that it is not a problem compared to the nichrome wire type. (5
), there is no need to worry about wire breakage in the furnace with the present invention.

As mentioned above, the tray type heating element of the present invention solves the serious drawbacks of the nichrome wire type heating element.
In addition to this, it also has the following advantages:

Advantage (a): The heat medium circulation type shelf-type far-infrared radiator of the present invention can serve both as a heating element that heats the material to be dried and as a shelf board on which the material to be dried is placed. It is. Therefore, in the case of several heating shelves, one shelf can heat both the upper and lower heated objects. (
This means that the object to be heated is heated from above and below (direct heat transfer and radiant heat to the object above, and radiant heat to the object below). With the nichrome wire method, a separate shelf board is provided on which the object to be heated is placed, and a nichrome wire tube is hung on it at a distance of about 150 mm, and only the object under the tube is radiated. That's what I do. From the perspective of the object to be heated, it is only radiantly heated from above.

Advantage (a): In the method of the present invention, there is no need to provide electrical wiring to the shelves, so the furnace shelves can be easily made into a movable cart type. (Line automation is easy) Advantage (c): Nichrome wire tube type has various problems under high temperature, high pressure, or reduced pressure, and in many cases cannot be used in practice. However, the present invention There are no problems with the tiered type.

As described above, the present invention inherits the features of the nichrome wire far-infrared radiator system, solves all of its drawbacks, and also brings about a few advantages (in the far-infrared wavelength range). In order to radiate electromagnetic waves, the surface of the heating medium circulation tray is treated with titanium oxide, zirconia-based radiating material, etc.).

Note that in this text, (shelf) refers to box-shaped shelves, but also includes heated tube-type shelves that are bent.

(Treating the surface of the shelf with a metal oxide or the like) may mean treatment on both sides of the shelf, or treatment on one side only on the lower side. Furthermore, it is not limited to metal oxides, but also includes surface treatments using quartz and various ceramics for the purpose of emitting far-infrared rays.

(Resistance heating element type tube) also includes resistance heating element type panel heater.

[Brief explanation of the drawing]

Figure 1 (a) is an external view of the nichrome wire infrared radiator.
(a) is a cross-sectional view of a nichrome wire infrared emitter (tube);
(C) is an external view of the heat medium circulation type infrared radiation tray; (D)
1 is a cross-sectional view of a heat medium circulation type infrared radiation tray. In addition, the number 1 in the drawing is a tube. 2. is a terminal. 3. is the mounting leg. 4
, is a reflector. 5. is nichrome wire. 6. Insulating filling. 7
, is a metal tube or metal plate. 8. Metal oxides, etc. 9,
is the heat medium inlet. 10 indicates a heat medium outlet.

Claims (1)

[Claims] Shelves whose surface has been treated with metal oxide, etc.