JP6984581B2 - Equipment insulation method - Google Patents

Description

The present invention relates to a heat insulating method for reducing heat dissipation from an outer wall in a combustion furnace, a heating furnace, a molten metal container, or the like, in which the temperature of the outer wall thereof is 50 ° C. or higher (hereinafter referred to as high temperature equipment).

Since the outer wall of the high-temperature equipment becomes hot, heat dissipation is large, and when the outer wall temperature is 50 ° C or higher, the higher the temperature, the greater the risk of human body burns and damage to peripheral equipment such as nearby piping wiring and valve drive devices. It is desirable to lower the temperature.

Further, when the heat dissipation is large, the fuel consumption increases in order to maintain the inside of the high temperature equipment at a constant temperature, which causes a problem that the fuel cost increases. When reducing heat dissipation by heat insulation, the cost spent on it is required to be within the range of the reduction amount of the fuel cost due to the reduction of heat dissipation.

Patent Document 1 proposes a seal structure in which an inorganic heat insulating material layer made of an adhesive seal heat insulating material and a composite heat insulating material is provided on the outer surface of the high temperature equipment to prevent reduction of heat dissipation from the high temperature equipment. Has been done. However, in this method of providing the adhesive sealing material on the outer surface of the high temperature equipment, the piping wiring and valve drive device installed near the outer surface of the high temperature equipment become barriers, and it takes a long time to install the adhesive sealing material on the outer surface of the high temperature equipment. There was a problem that required.

Patent Document 2 proposes a technique for reducing radiant heat by using a paint having a low emissivity. However, this method cannot reduce heat dissipation to the outside air that rises and convects along the vertical outer wall surface at high temperature, and the effect is small.

Japanese Unexamined Patent Publication No. 3-115388 Japanese Unexamined Patent Publication No. 2012-31392

It is an object of the present invention to realize a heat insulating method that can be carried out in a short period of time at a cost within the range of the merit of reducing fuel cost in high temperature equipment and sufficiently lowers the outside air temperature.

The present invention solves the above problems by the following means.
[1] In equipment where the outer wall is 50 ° C or higher, a heat insulating material having a thermal conductivity of 0.2 W / (m · K) or less in the temperature range of 25 to 400 ° C is suspended outside the outer wall. Insulation method.
[2] The method for insulating equipment according to [1], wherein the gap between the heat insulating material and the outer wall is sealed at the upper end of the heat insulating material.
[3] A heat insulating paint having a thermal conductivity of 0.2 W / (m · K) or less in a temperature range of 25 to 400 ° C. is applied or sprayed on the outer wall, and the heat insulating material is suspended on the outside thereof. The method for insulating equipment according to 1] or [2].
[4] The outer wall is coated or sprayed with a heat insulating paint having a surface emissivity of 0.6 or less after being applied or sprayed, and the heat insulating material is suspended outside the heat insulating material [1] or [2]. Insulation method for equipment described in.
[5] The method for insulating equipment according to any one of [1] to [4], wherein the equipment is a heat storage chamber of a coke oven.

INDUSTRIAL APPLICABILITY According to the present invention, in high temperature equipment, it is possible to carry out construction in a short period of time at a cost within the range of the merit of reducing fuel cost, and it is possible to realize a heat insulating method that sufficiently lowers the outside air temperature.

1 (a), (c) to (f) are views showing an embodiment of the present invention. FIG. 1B is a comparative example in which the heat insulating material is not suspended.

Heat dissipation from the outer wall of high-temperature equipment is divided into heat dissipation to the outside air (called convection heat transfer) and heat dissipation by radiation of electromagnetic waves (called radiant heat transfer or radiant heat transfer). Both of the heat radiated by the above increases as the temperature of the outer wall increases. In particular, heat dissipation due to the radiation of electromagnetic waves increases at an accelerating rate as the temperature rises, and when the temperature exceeds about 100 ° C., the amount is comparable to heat dissipation to the outside air, and the total amount of heat dissipation also increases at an accelerating rate.

In addition, peripheral equipment such as piping, wiring, and valve drive devices are arranged on or near the outer wall of high-temperature equipment, and the close distance between the outer wall and peripheral equipment is only 1000 mm or less, so it takes time for conventional heat insulation construction. There are places where the conventional heat insulation work cannot be performed because the distance between the outer wall and the surrounding equipment is only about 100 mm. In particular, the heat storage chamber of the coke oven is several hundred mm near the outer wall.
A large number of exhaust gas valves and associated operating chains are installed at the pitch, and it takes a long time to install the heat insulating material on almost the entire outer wall.

Since the exhaust gas valve operates periodically during the operation of the coke oven, it is dangerous to work in close proximity, and when the work of installing the heat insulating material is performed, it is necessary to stop the operation during the work. Since the temperature change due to the stoppage and restart of the operation causes thermal stress cracking of the refractory, it is desirable to suppress the cooling of the refractory by setting the operation stop time to 6 hours or less, and the work of installing the heat insulating material is also 5 It is required to be less than an hour.

Therefore, the inventors have conceived that the work in the vicinity of the outer wall can be reduced by suspending the heat insulating material on the outside of the outer wall of the high temperature equipment. When suspending the heat insulating material on the outer wall, it is desirable that the thickness of the heat insulating material is thin from the viewpoint of whether or not the heat insulating material can be constructed depending on the close distance of the peripheral equipment close to the construction site, and from the viewpoint of the workability of the construction to be suspended on site. It is desirable that the weight of the heat insulating material is light. However, since the thickness of the heat insulating material is directly related to the heat insulating performance, there is a problem that the heat insulating performance is deteriorated when a thin heat insulating material is used. In order to solve this problem, it is effective to use a heat insulating material having a low thermal conductivity.

Generally, the thermal conductivity of steel is about 40 W / (m · K), and the thermal conductivity of refractories is about 2 W / (m · K). Hereinafter, the temperature range that defines this thermal conductivity is set to 25 ° C, which is a general working environment, as the lower limit, and 400 ° C, which is used in the design of high-temperature equipment, as the upper limit. If the thermal conductivity of the heat insulating material is 0.2 W / (m · K), which is one tenth of the general refractory, a steel housing 200 times thicker than the heat insulating material, or It is possible to obtain the same heat insulating effect as adding a refractory material with a thickness 10 times the thickness of the heat insulating material, and to suspend it to a place where peripheral equipment is close. There are many places where the close distance between the housing and peripheral equipment is about 100 mm, and by hanging a heat insulating material with a thickness of 50 mm here, the same effect as doubling the thickness of a refractory of 500 mm can be obtained. Be done. If the thermal conductivity of the heat insulating material is further lowered, the heat insulating effect can be further enhanced and the thickness can be made thinner.

By thinning the heat insulating material in this way, the weight of the heat insulating material can be reduced, the hanging work can be facilitated, and the hanging piece on the housing side for hanging can be made small and lightweight. The work of attaching the hanging piece to the housing is also reduced.

The material of the heat insulating material is not particularly limited, but a refractory material having a high porosity, a board-shaped or blanket-shaped ceramic fiber or ceramic particles, or a microporous material which is a molded product of ceramic fine particles of micron order or less is used. be able to. Further, if the outer wall is relatively cold, a vacuum heat insulating material can be used.

On the other hand, the heat-resistant temperature of the heat insulating material must be higher than the temperature of the application site, and when suspending, it is necessary to pay attention to the suspension position and the strength of the insulating material body for those with weakly molded ceramic particles or blanket-shaped materials. Therefore, if necessary, a thin steel material for reinforcement can be attached to the suspension position and the edge of the heat insulating material.

The heat insulating material may be integrated or divided, and a framework may be made of the above-mentioned thin steel material, and one or more sheets may be contained in the framework. Further, it is also possible to use heat insulating materials having different thicknesses and dimensions depending on the close distance between the outer wall of the high temperature equipment and the peripheral equipment.

FIG. 1A is a diagram showing an embodiment of the present invention, and is an example in which a heat insulating material is suspended from an outer wall.

The heat insulating material may be separated from the outer wall or adhered to the outer wall. From the viewpoint of heat insulation, it is disadvantageous to make them adhere to each other because heat transfer directly from the outer wall to the heat insulating material occurs. However, since the heat insulating material generally has a high void ratio or is formed by molding particles or fibers, even if the heat insulating material is brought into close contact with the outer wall, the contact point is close to point contact, so the contact area is small and the heat insulating material is applied from the outer wall. Direct heat transfer to is smaller than convection heat transfer and radiant heat transfer.

On the other hand, when the heat insulating material is suspended away from the outer wall, the air in the gap between the outer wall and the heat insulating material may rise due to heat convection and flow out of the range of the heat insulating material, resulting in increased heat dissipation. It is thought that such heat dissipation due to heat convection of air is more likely to occur as the gap between the heat insulating material and the outer wall is large and the temperature of the outer wall is high, but the vertical dimension of the heat insulating material has a particular effect. When the vertical dimension of the heat insulating material is 800 mm or more, it is observed that the outflow of air becomes severe due to the chimney effect.

If the gap between the heat insulating material and the outer wall is sealed at the upper end of the heat insulating material, heat dissipation due to this heat convection can be reduced. As a method of sealing between the upper end of the heat insulating material and the outer wall, completely airtightness such as welding of steel material may be used, but if the work space is limited, a cloth-like or wool-like material having low airtightness may be used at the upper end. You may just fill the gap. It may be covered with or filled with a film of a heat-resistant resin such as metal tape or polyimite.

FIG. 1F is an example in which the gap between the heat insulating material and the outer wall is sealed at the upper end of the heat insulating material.

The present invention is particularly effective when the peripheral equipment is close to the outer wall of the equipment to be insulated and it is difficult to construct the insulation. It has a particularly remarkable effect in the heat storage chamber of a coke oven in which an exhaust gas valve and an operating chain attached to it are installed in the vicinity of the outer wall at intervals of several hundred mm, and the construction time on site is only reduced to a fraction. In addition, heat insulation can be applied to places that could not be installed in the past.

As a method of applying the heat insulating material to a narrow construction place, it is conceivable to apply or spray the heat insulating paint on the outer wall other than the present invention. However, the thickness of the heat insulating paint cannot be sufficiently obtained by coating or spraying, and a sufficient heat insulating effect cannot be obtained. In the present invention, since the heat insulating material is suspended from the outside of the outer wall, it can be used in combination with the application or spraying of a heat insulating paint having a insufficient heat insulating effect by itself, and a larger heat insulating effect can be obtained by combining them. The heat insulating paint applied or sprayed on the outer wall is not particularly limited, and the heat resistant temperature, thermal conductivity, and workability may satisfy the conditions of use.

FIG. 1B is a comparative example in which a heat insulating paint is applied to the outer wall.

1 (c) to 1 (e) are examples of the present invention in which a heat insulating paint and a heat insulating material are combined.

As the heat insulating paint applied or sprayed on the outer wall, a high heat insulating effect can be obtained by using a heat insulating paint having a surface emissivity of 0.6 or less after being applied or sprayed. As mentioned above, heat dissipation from the outer wall is divided into heat dissipation to the outside air (called convection heat transfer) and heat dissipation by radiation of electromagnetic waves (called radiant heat transfer or radiant heat transfer), but it is due to radiation of electromagnetic waves. The heat radiation increases at an accelerating rate as the temperature rises, and when it exceeds about 100 ° C, the amount of heat heat is comparable to the heat heat to the outside air. This is because heat dissipation can be reduced more effectively by applying or spraying the heat insulating paint.

However, since a substance having a low emissivity generally has a high thermal conductivity, unless the emissivity of the heat insulating paint is sufficiently lower than that of a general heat insulating material, it is offset by the high thermal conductivity and no effect can be obtained. The emissivity of a general heat insulating material is about 0.95, and when the emissivity of the heat insulating paint is 0.6 or less, the effect of reducing heat radiation due to the radiation of electromagnetic waves is improved, and the higher the temperature, the higher the emissivity of heat radiation. The temperature range that defines this emissivity is 25 ° C, which is a general working environment, and the upper limit is 400 ° C, which is used in the design of high-temperature equipment. Here, when the value of the emissivity of the heat insulating paint is not presented as the specification of the material or when the properties such as the unevenness of the surface change, it can be measured by JIS A 1423 (1983). Applying a heat insulating paint with a low emissivity to the inner and outer surfaces of the heat insulating material seems to have the effect of reducing heat dissipation, but the effect is smaller than that of applying it to the outer wall.

Generally, the distance between the outer wall and the peripheral equipment is about 50 mm, and the thickness of the heat insulating material is required to be 30 mm or less in consideration of the gap for inserting tools and hands for construction. If the thermal conductivity of the heat insulating paint is high, it is necessary to increase the thickness of the heat insulating material in order to secure the heat insulating effect, and there are cases where the thickness must be 30 mm or more. Since the heat insulating paint can be applied to the outer wall in advance by coating or spraying, it is possible to avoid an increase in the thickness of the heat insulating material by setting the thermal conductivity of the heat insulating paint to 0.2 W / (m · K) or less. The temperature range is 25 to 400 ° C. for the same reason as the above-mentioned heat insulating paint.

As an example, various heat insulation works were carried out on the outer wall of the heat storage chamber of the coke oven. The effect of heat insulation was evaluated by measuring the atmospheric temperature at a place 100 mm away from the outer wall of the heat storage chamber of the coke oven.

The criteria were that the construction time was 5 hours or less, the outside air temperature was 140 ° C or less, and the cost could be reduced compared to the conventional method.

In Example 1, by using a heat insulating material having an extremely small heat transfer coefficient of 0.03 W / (m · K), the heat insulating cost increased, but the heat insulating effect reduced the heat dissipation and lowered the outside air temperature. The amount of reduction in fuel cost due to the decrease in heat dissipation exceeded the amount of increase in heat insulation cost, and the total cost could be reduced.

In Examples 2 to 5, a heat insulating material having a heat transfer coefficient of 0.2 W / (m · K) was used.

With a construction time of 5 hours or less, an outside air temperature of 140 ° C or less could be realized, the reduction in fuel cost exceeded the increase in heat insulation cost, and the total cost could be reduced.

In Example 4, a low thermal conductivity heat insulating paint was applied to the outer wall, and a heat insulating material was hung on the outside thereof. The outside air temperature was lowered by 30 ° C. with respect to Example 3, and a greater synergistic effect was obtained as compared with the heat insulating paint alone. It is considered that this is because the temperature of the heat insulating material on the outside is lowered by the heat insulating paint and the thermal conductivity of the heat insulating material is lowered.

In Example 5, a low emissivity heat insulating paint was applied to the outer wall, and a heat insulating material was hung on the outside thereof. The outside air temperature was lowered by 45 ° C. with respect to Example 3, and a greater synergistic effect was obtained as compared with the heat insulating paint alone. It is thought that this is because the heat insulating paint lowered the temperature of the heat insulating material on the outside and the thermal conductivity of the heat insulating material decreased, and the heat insulating material raised the temperature of the heat insulating paint and the contribution of the radiation reduction effect increased. Be done.

In Example 6, the heat insulating paint was applied to the outside of the heat insulating material in advance, and in Example 7, the heat insulating paint was applied to the inside of the heat insulating material in advance and then hung on the outside of the outer wall. Since both the heat insulating material and the heat insulating paint were adopted, the outside air temperature could be lower than in Examples 1 to 3. Among Examples 5, 6 and 7 with the same heat insulation cost, Example 5 was able to lower the outside air temperature most, but this is because Example 5 exerts a heat dissipation prevention effect at a higher temperature. It is considered that the heat dissipation from the outer wall is further reduced because the low emissivity paint is applied to the hottest part.

In Comparative Example 2, the construction time was large and unsuitable because the heat insulating material was not suspended but adhered to the outer wall. This is due to the small work space.

In Comparative Example 3, brick was used as a heat insulating material. Ordinary bricks were set in advance on the frame and made into a panel, which was hung on the outside of the outer wall. Since the heat transfer coefficient is as large as 0.6 W / (m · K), the outside air temperature did not fall below 140 ° C. even though the thickness was set to 65 mm. Also, it took 6 hours construction for heavy thick cross heated material.

In Comparative Example 4, since only the heat insulating paint was used and no heat insulating material was used, heat dissipation was large, the outside air temperature was high, and the amount of fuel cost reduction was small, which was unsuitable.

Claims (4)

In equipment where the outer wall is 50 ° C or higher, the heat insulating material is applied after applying the heat insulating paint to the surface of the heat insulating material having a thermal conductivity of 0.2 W / (m · K) or less in the temperature range of 25 to 400 ° C. A method for insulating equipment by suspending it from the outside of the outer wall and sealing the gap between the heat insulating material and the outer wall at the upper end of the heat insulating material. To the outer wall, only coating or spraying a heat insulating coating thermal conductivity in the temperature range of 25 to 400 ° C. is 0.2W / (m · K) or less, hanging the heat insulating material on its outside, in claim 1 Insulation method for the equipment described. The method for insulating equipment according to claim 1 , wherein the outer wall is coated with or sprayed with a heat insulating paint having a surface emissivity of 0.6 or less after being applied or sprayed, and the heat insulating material is hung on the outside thereof. .. The method for insulating equipment according to any one of claims 1 to 3 , wherein the equipment is a heat storage chamber of a coke oven.

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