JPH0445229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing heat insulating material from scattering and spreading when repairing equipment such as steam turbines and pumps covered with heat insulating material.

Steam turbines, pumps, feed water heaters, valves, deaerators, and other equipment in thermal power plants are covered with silica boards, glass wool, rock wool, and other heat-insulating materials, so when repairing these equipment, It is necessary to dismantle the heat insulation equipment that has been constructed in advance. In normal cases, repairs must be completed in a short period of time considering the operating rate of the above equipment, so after the equipment has been operating at high temperatures for a long period of time, it is necessary to stop the equipment and then allow the equipment to cool down to ambient temperature. They are dismantling the heat insulation equipment without waiting for it. As a result, fine powder from the heat insulating material generated during demolition work was carried over a wide area by the rising air currents due to high temperatures, and had a significant impact on other equipment operating in the vicinity.

The applicant previously proposed a scattering prevention facility in which a device is covered with an enclosure to prevent the fine powder of heat insulating material from scattering, and a suction dust collector is connected to the enclosure. is unstable and there is a temperature difference in the space inside the enclosure, so the insulating fine powder that is removed from the high-temperature rising air spreads throughout the enclosure in a short period of time, causing the dust concentration inside the enclosure to increase extremely. As a result, the internal working environment deteriorated.

The present invention focuses on the air flow inside the enclosure body, which has not been considered in the past, and introduces the air flow into the enclosure body so that the air flow carrying dust due to high temperature natural convection is transferred to the suction port. This invention relates to a method for preventing scattering and dispersion in which fine powder that is dispersed in an enclosure body by a flow is collected at a suction port and collected by a suction dust collector.

This will be explained in detail below along with examples.

In the figure, an enclosure main body 2 surrounding equipment 1 such as a steam turbine has a size that limits the working space necessary to regulate dust concentration, and supports 3 formed to straddle the equipment 1... It is made by pasting a nonflammable sheet 4 on the The support is constructed by assembling appropriate columnar materials around the equipment so that it can stand on its own, but it can also be configured in a bellows style to make it expandable and retractable, or it can be equipped with casters, wheels, or rails at the lower end. It can also be provided movably. As shown in FIG. 3, an enclosing block 5 having an appropriate space is formed, and the enclosing block 5
It is also possible to create an enclosure body 2 of a desired size by connecting a required number of them. The ceiling and side parts of the enclosure body 2 are preferably formed by bonding several sheets together. For example, the ceiling part is made up of four sheets, the side parts are made up of two to four sheets, and the edges are provided with a sheet fastener ( (not shown) and are removably joined. In this way, it is easy to attach and detach the seat, and when transporting into and out of large equipment such as a steam turbine in a thermal power plant, the seat can be removed to enlarge the work space, which is convenient. Furthermore, if a removable partition sheet 6 similar to the above-mentioned sheet is provided in the enclosure main body so that it hangs down, the internal volume can be appropriately selected and set, and therefore the floating area of fine dust can be limited ( Figure 2). As shown in FIG. 4, the sheet 4 in the cross-sectional direction of the device 1 is divided into an appropriate number of parts, and the sides 7 of each sheet part are fastened with fasteners 8.
If you connect them so that they can be opened and closed, you can create a sealed situation inside the enclosure to match the shape of the device. The entrance/exit can be formed on an appropriate side surface, and it is preferable to partition a part of the seat and provide a door 9 which can be opened and closed with a fastener 10.

An air flow is introduced into the enclosure main body 2 so as to transfer the rising air current generated from the equipment in the direction of suction provided on the side surface or ceiling of the enclosure main body, which will be described later. In the figure, fresh outside air outside the enclosure body is forcibly blown into the enclosure body from an air outlet 13 through an air transfer pipe 12 by an air blowing device 11 such as a blower or compressor provided outside the enclosure body.
The air outlet 13 can be provided in an appropriate number at an appropriate position. For example, in the one shown in FIG.
A stand 14 is movably placed approximately in the center of the enclosure, and discharge ports 13, 13 facing both sides are provided on the stand. A discharge port can be provided. Note that the transfer pipe 12 of the discharge port 13
The discharge port is constructed of a flexible tube, or a flexible joint is provided on the support portion of the discharge port so that the discharge port can be directed in any direction toward the suction port, avoiding the operator working inside the enclosure main body. Further, an air volume adjusting device 15 is provided in the middle of the air blowing device 11 or the transfer pipe 12 to adjust the amount of air blown. In this case, consider the volume of the enclosure body and the amount of suction from the suction port (described later), and make sure that the inside of the enclosure body is always maintained at a negative pressure to prevent the dust inside the enclosure from leaking to the outside. . Under this condition, the amount of air required to collect the dust generated inside the enclosure from the suction port is:
The amount of suction from the suction port should be about 15% to 25%, preferably about 20%.

On the wall of the enclosure main body 2 facing the air flow,
A suction port 16 is formed to suck the air flow, and a suction dust collector 18 is connected to the suction port 16 via a dust transfer duct 17. The suction port 16 has a suction hood 19 formed around it, a hook-and-loop fastener 20 provided at the opening edge of the hood 19, and the hook-and-loop fastener 20 engaged with a hook-and-loop fastener 22 provided at the periphery of the opening 21 of the sheet. Attach to the seat (Figures 5 and 6). An appropriate number of openings may be provided in the sheet at appropriate positions, and blind sheets 24 having hook-and-loop fasteners 23 on the periphery may be attached to the openings where the hood is not attached, as shown in FIG. . In this way, the suction port can be moved to any position such as up, down, right, left, etc., and if the blind sheet is made of a transparent sheet, it can also be used as a monitoring window.

As shown in FIG. 8, the inclination angle θ of the suction hood is determined to be β<90 when dust carried by the airflow from the air outlet 13 travels at an angle β with respect to the central axis after colliding with the hood. °, it is considered that the fluid is smoothly sucked into the suction port. Therefore, if the angle of the air flow (dust flow) with respect to the central axis is α, then the relationship β=α+2θ<90° is sufficient. Here, the radius of the hood is A
m, and if the distance from the air outlet to the hood is Dm, then tanα=A/D... From the above formula, if the radius of the hood and the distance from the air outlet to the hood are determined, the inclination angle θ of the hood is determined. . For example, when the diameter of the hood is 2 m and the distance is 5 m, the inclination angle θ is θ<39.3°.
The hood may have a conical or pyramidal shape, and in the case of a pyramidal shape, the value of A may be the distance from the central axis to the outer edge of the hood. According to experiments, when the width of the enclosure body is 10 m, if the air outlet is provided in the center, D = 5 m, the hood diameter is 2 m, and the inclination angle θ of the hood is θ < 35° with some allowance. Appropriate results were obtained. It is clear that if the angle α is small and the air flow (dust flow) advances toward the central axis, it will flow into the suction port more smoothly.

In addition, the speed of the air flow that transports the dust is such that the dust that flies up during the dismantling work of the insulation material moves while riding on the air flow discharged from the discharge port while falling due to gravity. If the falling distance is determined to be within the suction area of the suction hood, the dust collection effect will be good. Then, the speed of the air flow is v (m/s), the falling speed of the dust is w (m/s),
Falling distance of dust (effective dimension of suction hood) h
(m), and the moving distance of dust l (m), then h=l/v×w Here, assuming that the true specific gravity (dust specific gravity) of silica board, glass wool, rock wool, etc. used as a heat insulating material is approximately 2.0, If the size (particle size) of long-suspended dust to be collected is 4 to 20 μ, w =
0.06 to 1.3 (m/s). Also, if the effective dimension of the suction hood is 2m and the maximum moving distance is 5m as mentioned above, then v=l/h・w=5/2×(0.06~1.3) =0.15~3.25 (m/s) Therefore, the speed of the air flow is 0.15 to 3.25 m/s
According to the experimental results, a flow velocity of about 3 m/s gave good results.

As shown in the schematic diagram of FIG. 9, a device 1 such as a steam turbine is surrounded by an enclosure main body 2, and while the above-mentioned air blower 11 and suction dust collector 18 are operated, a heat insulating material is placed inside the enclosure main body. When carrying out demolition work,
The fine powder of the heat insulating material tends to be scattered by the rising airflow generated from the equipment, but it is sucked into the suction port 16 via the suction hood 19 by the airflow 25 introduced into the enclosure main body, and is collected. The airflow carrying dust due to high-temperature natural convection by the forced airflow is forcibly guided toward the suction hood, and almost all of the fine dust is sucked. Fine dust from insulation materials that do not take part in high-temperature natural convection,
The forced air flow 25 generates an induced flow 26 in such a manner that the air around the air flow is attracted, and the air is drawn toward the air flow 25 and sucked into the suction port.

The present invention is constructed as described above, and in a method for preventing scattering and dispersion of heat insulating material fine powder, which collects dust by suctioning upward airflow generated within an enclosure main body from a suction port, Since an air outlet for blowing outside air is provided inside the main body, it is possible to perform local forced air blowing with directionality within the enclosure main body.
Due to the local forced air flow, the air flow carrying dust due to high temperature natural convection is forcibly guided to the suction port, and almost all of the fine powder is sucked. At this time, the forced air is directional, so if you adjust the direction of the air outlet so that it directs the air to the suction port only at the location where dust is generated, the operator performing the above work inside the enclosure body can This allows the air to be blown while avoiding the above, creating a safe work environment that complies with the Industrial Safety Enforcement Regulations. Furthermore, since the air flow rate is set to 15% to 25% of the suction volume, a negative pressure is maintained inside the enclosure, which creates gaps at the floor and contact points with equipment, and there is a risk of outside air infiltrating. Even with a half-open enclosure structure like this, fine dust will not be scattered to the outside, and since the maximum air volume was set to within 25% of the suction volume, it is recommended to Even if the enclosure body tries to expand due to the blowing air, it is possible to secure enough negative pressure to prevent this expansion, and strong winds will disturb the airflow of dust and cause the dust to spread inside the enclosure body. In addition, by setting the ratio to 15% or more, it is possible to perform a minimum amount of forced air with directionality, and it is possible to collect dust effectively, without the need for large-scale equipment. It is possible to control the dust concentration within a given period of time, provide a good working environment, and prevent contamination of the surroundings of the work place.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a sectional view, FIG. 2 is a plan view, and FIG. 3 is a perspective view of a modified example.
4 and 5 are front views of the seat, FIG. 6 is an enlarged sectional view of the suction hood portion, FIG. 7 is an enlarged sectional view of the blind seat portion, and FIG. 8 is an explanatory diagram of the inclination angle of the suction hood. FIG. 9 is a schematic diagram. 1... equipment, 2... enclosure main body, 13... air discharge port, 16... suction port, 18... suction dust collector,
19...Suction hood.

Claims (1)

[Claims] 1. In a method for preventing the scattering and dispersion of heat insulating material fine powder, which involves surrounding equipment insulated with heat insulating material with an enclosure body, and collecting dust by suctioning the rising airflow generated when the heat insulating material is dismantled through a suction port. , an air discharge port is provided for blowing outside air into the main body so as to transfer the rising airflow toward the suction port, and the amount of air blown from the discharge port is 15% to 25% of the amount of suction from the suction port, as described above. A method for preventing scattering and dispersion of heat insulating material fine powder, which is characterized by maintaining a negative pressure state within the enclosure body.