JP7583364B2 - Pipe heating device and pipe heating method - Google Patents

Description

The present invention relates to a pipe heating device and a pipe heating method. More specifically, the present invention relates to a pipe heating device for heating a fluid in a pipe and a method for installing the same.

Among the piping installed in the plant, there is a piping through which an aqueous solution of inorganic salts with an increased inorganic salt concentration to the solubility level flows. For example, when inorganic salts are the substances to be recovered, increasing the inorganic salt concentration reduces the amount of liquid to be handled for the same amount of inorganic salts, making it possible to make the equipment smaller and reducing the cost of the equipment. It also reduces the cost of energy, such as electricity, required for operations such as flow, stirring, and heating. In particular, when recovering inorganic salts as crystals, crystallization generally involves a concentration operation, so it is essential to increase the inorganic salt concentration in order to perform the concentration operation efficiently and economically. An example of such a plant is a nickel sulfate crystal manufacturing plant that handles a high-concentration aqueous solution of nickel sulfate. However, in such piping, when the pump is stopped in a low-temperature situation such as during the cold winter, the flow of the fluid stops and the fluid cools, which can cause crystals to precipitate in the piping. This can cause the piping to become clogged, resulting in a problem that the pump cannot be restarted.

In order to prevent crystallization of the fluid inside the pipes, the pipes can be heated. One method of heating the pipes is known to be pipe tracing, in which a tube carrying a heat transfer medium such as high-temperature steam is laid along the pipes (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 64-76680

When the tube is placed along the outer surface of the pipe, the tube and the pipe are in line contact. Because the contact area between the tube and the pipe is small, the efficiency of heat exchange between the heat medium and the fluid inside the pipe is low. In other words, there is a problem that efficient heating is not possible.

In view of the above circumstances, the present invention aims to provide a pipe heating device and a pipe heating method that have high heating efficiency.

The pipe warming device of the first invention is arranged along the outer surface of a pipe through which a fluid flows, and comprises a tube through which a heat transfer medium flows, and an insulating cylinder covering the pipe and the tube, and is characterized in that when the insulating cylinder is tightened, the tube is pressed against the pipe and crushed while maintaining an internal space through which the heat transfer medium flows.
The pipe warming device of the second invention is characterized in that, in the first invention, the tube is made of polyurethane or polyamide, and the heat-insulating cylinder is made of foamed plastic.
The pipe warmer of the third invention is the pipe warmer of the first or second invention, characterized in that the pipe is made of polyvinyl chloride and the heat medium is hot water at 30 to 60°C.
The pipe heating method of the fourth invention is characterized in that a tube for flowing a heat transfer medium is placed along the outer surface of a pipe through which a fluid flows, the pipe and the tube are covered with an insulation cylinder, and the insulation cylinder is tightened so that the tube is pressed against the pipe and collapsed while maintaining an internal space through which the heat transfer medium flows.
A fifth aspect of the present invention is a pipe heating method according to the fourth aspect of the present invention, characterized in that the tube is made of polyurethane or polyamide, and the heat-insulating cylinder is made of foamed plastic.

According to the first aspect of the present invention, since the tube is pressed against the piping and crushed, the contact area between the tube and the piping is increased, and the efficiency of heat exchange between the heat medium and the fluid in the piping is increased, resulting in high heating efficiency.
According to the second aspect of the present invention, since both the tube and the heat-insulating cylinder have appropriate flexibility, the tube can be appropriately crushed by tightening the heat-insulating cylinder.
According to the third aspect of the present invention, since the heat medium is hot water, even piping made of polyvinyl chloride, which has low heat resistance, can be heated.
According to the fourth aspect of the present invention, the tube is pressed against the piping and collapsed, so that the contact area between the tube and the piping is increased, and the efficiency of heat exchange between the heat medium and the fluid in the piping is increased, resulting in high heating efficiency.
According to the fifth aspect of the present invention, since both the tube and the heat-insulating cylinder have appropriate flexibility, the tube can be appropriately crushed by tightening the heat-insulating cylinder.

FIG. 2 is a cross-sectional view of the pipe warming device according to one embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 4 is an explanatory diagram of a method for installing the pipe heating device.

Next, an embodiment of the present invention will be described with reference to the drawings.
(Pipe heating device)
As shown in Figures 1 and 2, a pipe warming device AA according to one embodiment of the present invention is provided on a pipe PP through which a fluid flows. The pipe warming device AA has a tube 10 through which a heat medium flows. The tube 10 is arranged along the outer surface of the pipe PP. There is no particular limitation on the number of tubes 10, and there may be one or more. In the example shown, two tubes 10 are arranged to sandwich the pipe PP. The pipe PP and the tube 10 are covered by a thermally insulating tube 20. The outer surface of the thermally insulating tube 20 is covered by a skin 30.

The tube 10 is a general-purpose tube with a perfectly circular cross section when no external force is applied. As described below, when the pipe heating device AA is installed, the heat-retaining tube 20 is tightened. As a result, the tube 10 is pressed against the pipe PP and crushed to the extent that the cross section becomes elliptical. That is, as shown by the dashed line in FIG. 1, the tube 10, which has a perfectly circular cross section, is crushed to become elliptical. Note that the "elliptical shape" referred to here does not have to be a mathematically precise ellipse. It may be an asymmetric shape such as a crescent or a magatama. It is sufficient that the tube 10 is crushed while maintaining the internal space through which the heat medium flows. When a perfect circle is crushed while maintaining its circumference, its cross-sectional area decreases as it is crushed. The ratio (area ratio) of the cross-sectional area after crushing to the cross-sectional area of the tube 10 when no external force is applied is preferably about 0.6 to 0.9.

In this way, the tube 10 is pressed against the pipe PP and crushed, so the contact area between the tube 10 and the pipe PP is increased. This increases the efficiency of heat exchange between the heat medium in the tube 10 and the fluid in the pipe PP, resulting in high heating efficiency.

The heat medium flowing through the tube 10 is not particularly limited, but when the pipe PP is made of polyvinyl chloride, it is preferable to use hot water at 30 to 60°C. Since the heat resistance temperature of polyvinyl chloride is about 60 to 80°C, for example, if high-temperature steam is used as the heat medium, the pipe PP may soften. If hot water is used as the heat medium, even the pipe PP made of polyvinyl chloride, which has low heat resistance, can be heated without any problems. A method of wrapping a ribbon-shaped electric heater is also commonly used, but since the surface temperature of the ribbon reaches 100°C or more in most cases, it is necessary to select an appropriate electric heater. Furthermore, electric heaters have the disadvantage of being expensive to introduce. Therefore, it is preferable to use hot water at 30 to 60°C as the heat medium for low-temperature heating of the fluid flowing through the polyvinyl chloride pipe PP.

(Construction method)
Next, a method for installing the pipe heating device AA will be described.
3, first, the tube 10 is placed along the outer surface of the pipe PP. Next, the pipe PP and the tube 10 are covered with the heat-insulating cylinder 20. For example, the heat-insulating cylinder 20, which has a vertical slit, is opened, and the pipe PP and the tube 10 are sandwiched therebetween.

Next, the heat-insulating cylinder 20 is tightened by, for example, attaching adhesive tape to the joint of the heat-insulating cylinder 20. Then, as shown in FIG. 1, the tube 10 is pressed against the piping PP and is crushed to the extent that its cross section becomes elliptical.

For the tube 10 to be appropriately crushed, both the tube 10 and the heat-retaining tube 20 must have an appropriate degree of flexibility. For example, if the heat-retaining tube 20 is too softer than the tube 10, the tube 10 will not deform. On the other hand, if the heat-retaining tube 20 is too hard than the tube 10, the tube 10 will be completely crushed and the heat transfer medium will not flow.

Examples of tubes 10 with suitable flexibility include tubes made of polyurethane or polyamide. Although not particularly limited, a tube with an outer diameter of about 10 mm, an inner diameter of about 6.5 mm, and a weight of about 54 g/m is preferable. In addition, a tube with a minimum bending radius of about 15 to 30 mm measured using a method based on JIS B 8381 and a minimum mounting radius of about 20 to 45 mm measured using a vice type is preferable.

An example of the heat-insulating cylinder 20 having appropriate flexibility is a heat-insulating cylinder made of foamed plastic. Although not particularly limited, a heat-insulating cylinder having an expansion ratio of about 25 to 35 times, an apparent density measured by a method based on JIS K 6767 of ^about 30 to 40 kg/m3, and a 25% compression hardness of about 30 to 50 kPa is preferable.

When such a tube 10 and heat-insulating cylinder 20 are used, both have a suitable degree of flexibility, so that the tube 10 can be crushed to a suitable degree by tightening the heat-insulating cylinder 20. Also, since the heat-insulating cylinder 20 deforms to fit the tube 10, there is no need to machine grooves or the like on the inner surface of the heat-insulating cylinder 20 to accommodate the tube 10. In contrast, when the commonly used porous heat-insulating material made of calcium silicate is used as the heat-insulating cylinder 20, it is necessary to machine grooves of a suitable cross-sectional shape on the inside of the heat-insulating cylinder 20 in order to crush the tube to an oval shape.

AA Pipe heating device 10 Tube 20 Heat retention tube 30 Cover

Claims (3)

a tube arranged along an outer surface of a pipe through which a fluid flows and through which a heat transfer medium flows;
A heat-insulating cylinder that covers the piping and the tube,
The tube is pressed against the piping by the tightening of the heat-retaining cylinder, and is crushed while maintaining an internal space through which the heat medium flows.
The tube is made of polyurethane or polyamide, and has a minimum bending radius of 15 to 30 mm as measured by a method based on JIS B 8381;
The heat-retaining cylinder is made of foamed plastic, and has an apparent density of 30 to 40 kg/m ³ and a 25% compression hardness of 30 to 50 kPa, as measured by a method based on JIS K 6767. The piping is made of polyvinyl chloride,
2. The pipe warmer according to claim 1 , wherein the heat medium is hot water at 30 to 60 degrees Celsius. A tube for flowing a heat transfer medium is arranged along an outer surface of a pipe through which a fluid flows;
Cover the piping and the tube with a heat-insulating tube;
The heat-retaining cylinder is tightened so that the tube is pressed against the piping and collapsed while maintaining an internal space through which the heat medium flows;
The tube is made of polyurethane or polyamide, and has a minimum bending radius of 15 to 30 mm as measured by a method based on JIS B 8381;
The heat-retaining cylinder is made of foamed plastic, and has an apparent density of 30 to 40 kg/m ³ and a 25% compression hardness of 30 to 50 kPa, as measured by a method based on JIS K 6767.