JPH0330759Y2 - - Google Patents

Description

[Detailed explanation of the idea] Industrial applications The present invention relates to a gas-water heat exchanger.

Prior art and its problems Gas-water heat exchangers generally have poor heat transfer performance because the heat transfer coefficient on the gas side is low. For example, when a coil type heat exchanger is used as an economizer (feed water preheater for boiler exhaust heat recovery), it has the advantage of low pressure loss on the gas side and is lightweight, but has a problem with heat transfer performance.

An object of the present invention is to provide a gas-water heat exchanger that can solve the above problems and improve heat transfer performance in heat exchange between high-temperature gas and water.

Means for Solving the Problems The above object of the present invention is to provide a heat storage cylinder made of a high emissivity material having openings at both ends, a coiled heat transfer tube for water passage wound around the outer circumference of the heat storage cylinder, A gas-water heat exchanger comprising a heat storage cylinder and a casing that accommodates the heat transfer tube, wherein the casing supplies high-temperature gas from one end side of the heat storage cylinder to the inside and outside of the heat storage cylinder. The heat storage cylinder is provided with a gas supply port and a gas discharge port so as to discharge the gas from the other end side, and the heat storage cylinder has a plurality of gas passage holes formed in the peripheral wall, and a pressure regulating damper is provided in the other end side opening. This is achieved by a gas-water heat exchanger characterized by:

The coiled heat transfer tube may be wound in a single layer around the outer periphery of the heat storage tube, increasing the heat transfer area of the heat transfer tube, promoting turbulence of the gas flow, and improving the heat transfer rate. Therefore, it is preferable that the wire be wound in multiple layers.

Further, the damper is arranged at one end side of the heat storage cylinder.
However, in order to equalize the gas ejection speed from the gas passage hole and promote turbulence,
Furthermore, other dampers may be provided at appropriate locations.

Examples of the high emissivity heat storage material constituting the heat storage cylinder include ceramics, refractories, and the like. Examples of ceramics include those whose main component is alumina (emission rate ε = about 0.93), and those whose main component is magnesia (emission rate ε = 0.55).
Examples of refractories include high alumina castable refractories and high alumina plastic refractories.

As a heat storage cylinder, we also use a general metal cylinder whose surface is coated with heavy oil (emission rate ε=
0.99) may be used.

Function In the heat exchanger of the present invention, high-temperature gas is supplied from one end to the inside and outside of the heat storage tube made of high emissivity material.
A pressure regulating damper is provided at the opening on the other end side of the heat storage cylinder. The gas supplied to the outside of the heat storage cylinder is
The gas passed between the heat exchanger tubes and supplied to the inside of the heat storage cylinder flows out from the gas passage hole in the heat storage cylinder peripheral wall according to the opening degree of the damper and passes between the heat exchanger tubes,
The flows of both gases advance while becoming turbulent with each other due to the collision outside the cylinder and contact with the heat transfer tube. Further, the heat storage cylinder is heated and stores heat by such a high-temperature gas flow. Therefore, the water passing through the heat transfer tube is heated by both the transfer heat from the high temperature gas that convects while contacting the heat transfer tube and the solid radiant heat from the heat storage tube.

Effects of the invention The heat exchanger of the present invention is equipped with a heat storage tube made of a high emissivity material and has a large number of gas passage holes, and high-temperature gas is supplied inside and outside of the heat storage tube, so that part of the heat contained in the gas is Heat is stored in a heat storage cylinder with a high thermal radiation rate, and solid radiant heat from the heat storage cylinder improves heat transfer performance to water in the heat transfer tube. Furthermore, since a pressure regulating damper is provided at the outlet side opening of the heat storage cylinder, an appropriate buffling effect can be provided by the damper, and a large gas turbulence can be obtained with low pressure loss. Based on this, the high-temperature gas efficiently contacts the heat exchanger tube, and the heat transfer performance to the water inside the heat exchanger tube improves. Therefore, according to the present invention, it is possible to perform excellent heat exchange by combining the above-mentioned good heat transfer performance due to solid radiant heat and high heat transfer performance based on efficient contact of turbulent gas with the heat transfer tube. A gas-water heat exchanger can be provided.

In addition, since the heat exchanger of the present invention has low pressure loss as mentioned above, even if it is installed and used in a boiler as an economizer, it will not have an adverse effect on combustion in the boiler. The initial temperature of the heat exchanger outlet water when OFF is also improved.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a gas-water heat exchanger according to one embodiment of the present invention. The heat exchanger H includes a heat storage cylinder 1 made of a high emissivity material and having openings 11 and 12 at both ends;
It includes a coiled heat exchanger tube 2 for water flow that is wound around the outer periphery of the heat storage cylinder 1, and a casing 4 that accommodates the heat storage cylinder 1 and the heat exchanger tube 2. The casing 4
is equipped with a cylindrical part 41 composed of a wall 412 containing a heat insulating material 411, and at both ends of the cylindrical part 41,
A gas supply port 42 and a discharge port 43 are provided for supplying high-temperature gas to the inside and outside of the heat storage cylinder 1 from one end side of the heat storage cylinder 1 and discharging it from the other end side of the heat storage cylinder 1.
These gas supply ports 42 and discharge ports 43 face both ends of the heat storage cylinder 1 and the heat transfer tubes 2 wound around both ends of the heat storage cylinder 1. The heat storage cylinder 1 has a large number of gas passage holes 14 formed in its peripheral wall, and a pressure regulating damper 3 is provided near the outlet opening 12 of the heat storage cylinder 1. The heat exchanger tube 2 is the heat storage cylinder 1
is wound in multiple layers, and water is supplied from a water supply port 21 and hot water is discharged from a hot water tap 22. The damper 3 is rotatably supported by the casing 4 so as to be able to open and close the outlet opening 12 of the heat storage cylinder 1 . In this embodiment, only one damper 3 is disposed on the outlet side of the heat storage cylinder 1, but other dampers may be provided, for example, at the position shown by the imaginary line in FIG. 1, if necessary. . By providing this other damper, it becomes possible to make the gas ejection velocity from the gas passage hole 14 more uniform and to promote turbulence.

The heat exchanger H configured in this way has a flue pipe 5 from the boiler B, as shown in FIG.
A gas supply port 42 of the casing 4 is connected to the gas supply port 42 of the casing 4, and a gas discharge port 43 is connected to the exhaust pipe 6.

In Figure 2, 7 is a water supply pipe, 8 is a hot water (or steam) pipe, 9 is a water supply pipe from pipe 7 to heat exchanger H, 91 is a pump, and 10 is from heat exchanger H returning to pipe 7. It's a pipe.

Water sent from pipe 9 to heat exchanger H is inlet 2
1 into the heat exchanger tube 2, and on the other hand, the exhaust high temperature gas from the boiler B passes through the flue 5 to the tube 1 in the heat exchanger H.
Enter inside and outside. Of this gas, the gas supplied to the outside of the cylinder 1 advances between the heat exchanger tubes, while the gas that has entered the cylinder 1 flows through the hole 14 of the cylinder wall 13 into the cylinder according to the opening degree of the damper 3. Go outside and heat transfer tube 2
It passes through the gap and moves forward toward the gas outlet 43. As a result, the interference between the gas flows inside and outside the cylinder 1 promotes turbulence in the gas flow around the heat transfer tube 2. During this time, heat is stored in the tube 1, and the water in the heat transfer tube 2 is preheated due to heat transfer from the gas and heat radiation from the tube 1, and exits from the outlet 22 and heads to the boiler B through the pipe 10. .

With the damper 3 in the above embodiment open,
When the heat transfer rate was determined with and without the tube 1, when the tube 1 was present, the heat transfer rate was improved by about 7 to 17% compared to the case without the tube 1. (See Figure 3).

This means that the heat transfer rate was improved by converting gas radiation into solid radiation.

In addition, when the damper 3 in the above embodiment was kept closed and the heat transfer rate was determined with and without the tube 1, the heat transfer rate with the tube 1 was approximately 20 to 26% higher than that without the tube 1. % (see Figure 3).

This means that the gas radiation is converted to solid radiation and the heat transfer rate is improved due to the buffling effect of the damper 3.

In addition, as can be seen from Fig. 4, when the damper 3 of the heat exchanger H was closed and the boiler temperature rise characteristics were investigated with and without cylinder 1, it was found that the temperature rise was 30°C. When used as a standard, when tube 1 is present, the improvement is approximately 14% compared to when tube 1 is not present.

Furthermore, as can be seen from Fig. 5, when the damper 3 of the heat exchanger H is closed, the heat exchanger outlet 2 is closed when the boiler is turned on and off, depending on whether the cylinder 1 is present or not.
When the temperature rise characteristics of the water in No. 2 were investigated, the initial temperature of the water was increased by 15% when tube 1 was present compared to when it was not present. This is based on the heat storage effect of the cylinder 1.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of one embodiment of the present invention;
The figure is an explanatory diagram of the usage state of the heat exchanger shown in Fig. 1, and Fig. 3 shows the damper in the embodiment shown in Fig. 1 in the open and closed states with and without the high emissivity porous heat storage cylinder. The obtained heat transfer rate K - air ratio n diagram, and Fig. 4 is the boiler temperature rise Δt - elapsed time t line obtained with and without the heat storage cylinder with the damper closed in the example of Fig. 1. 5 shows the temperature increase Δt− of the water at the heat exchanger outlet obtained with and without the heat storage cylinder with the damper closed in the example of FIG. 1.
It is an elapsed time t diagram. H... Heat exchanger, 1... Heat storage cylinder made of high emissivity material, 11, 12... Cylinder end, 13... Cylinder peripheral wall, 14
...Gas passage hole, 2...Heat transfer tube, 3...Damper,
4...Casing, 42...Gas supply port, 43...
...Gas outlet.

Claims (1)

[Scope of utility model registration request] A heat storage cylinder made of high emissivity material with openings at both ends,
A gas-water heat exchanger comprising a coiled heat transfer tube for water flow that is wound around the outer periphery of the heat storage cylinder, and a casing that accommodates the heat storage cylinder and the heat transfer tube,
The casing is provided with a gas supply port and a gas discharge port so that high-temperature gas is supplied from one end of the heat storage cylinder into the inside and outside of the heat storage cylinder and discharged from the other end of the heat storage cylinder, and the heat storage cylinder has a A large number of gas passage holes are formed in the gas passageway, and a pressure regulating damper is provided at the opening on the other end side.
Heat exchanger for water.