JPH05141883A - Fluidized layer heat exchanger - Google Patents

Abstract

PURPOSE:To prevent the solidification of a fluidized layer due to moisture and to make a heat transfer ratio of a heat exchanger uniform. CONSTITUTION:Heating means 7 having a shape for passing a stream from below, in which a speed of the passing stream becomes uniform irrespective of a place for passing the stream and for heating the passing stream is provided under a net filter 3. The heater 7 is, for example, a honeycomblike ceramic heater. Moisture between solid particles is evaporated by the air heated by the heater 7 to prevent solidification of a fluidized layer 4, and hence its heat transfer ratio is improved. Since the speed of the stream is the same at any place, the ratio is made uniform, and its heat exchanging ratio is improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a fluidized bed heat exchanger.

[0002]

2. Description of the Related Art Conventionally, there is a fluidized bed heat exchanger as shown in FIG. In this fluidized bed heat exchanger, a net filter 3 is fixed below a heat exchanger 2 fixed in a casing 1, a layer 4 of solid particles is provided on the net filter 3, and the net filter 3 is blown by a blower 5. Of air from above to fluidize the bed 4 of solid particles, and the fluidized solid particles 6 collide with the heat transfer surface of the heat exchanger 2, and the collision energy of the heat exchanger 2 The thermal boundary layer is destroyed to improve the thermal conductivity of the heat exchanger 2. When the heat exchanger 2 is used for heat exchange between the airflow and the low-temperature medium, when the surface temperature of the heat transfer surface is lower than the dew point temperature of the gas, the water content in the airflow is the surface of the heat transfer surface (the pipe 2a).
And the surface of the fin 2b) to be condensed and attached as water droplets to lower the thermal conductivity, but the fluidized solid particles 6 blow off the water droplets from the surface of the heat transfer surface, so that the thermal conductivity can be prevented from lowering. ..

[0003]

By the way, in the conventional fluidized bed heat exchanger, the water in the air stream or the water blown off and dropped adheres to the solid particles, and the solid particles adhere to each other to form solid particles. There is a problem that the layer 4 of No. 1 becomes an integral mass, increases ventilation resistance, and eventually solid particles do not flow, and thermal conductivity cannot be improved. In addition, since the flow velocity of the air passing through the net filter 3 is different at the place where it passes (in the example of FIG. 3, the flow velocity is faster at a position farther from the blower 5 and lower at a position closer to the blower 5), so that the thermal conductivity is uniform There was a problem that the heat exchange rate deteriorated. Therefore,
The object of the present invention is to improve the thermal conductivity by preventing solid particles from adhering moisture to each other so as to prevent the solid particles from adhering to each other, and at the same time, regardless of where the flow velocity of the air passing through the net filter 3 is passed. It is to provide a fluidized bed heat exchanger that is made uniform.

[0004]

In order to achieve the above-mentioned object, the present invention provides a heat exchanger in the passage of the air flow from the lower side to the upper side, and places a layer of solid particles under the heat exchanger. A perforated plate-like member is provided, and the layer of solid particles is fluidized by the air flow so that the solid particles collide with the heat transfer surface of the heat exchanger to destroy the temperature boundary layer of the heat exchanger. In the fluidized bed heat exchanger described above, below the perforated plate-like member, the airflow is made to have a uniform shape regardless of where the airflow passes and where the airflow passes, and It is characterized in that a heating means for heating is provided. The heating means may be a honeycomb ceramic heater.

[0005]

In the above structure, the air current flowing from the lower part to the upper part passes through the heating means, and the heating means makes the flow velocity uniform regardless of the place where it passes and is heated to form a layer of solid particles. The water between the solid particles is sent and heated by the heated air flow to evaporate, the bond due to the water between the solid particles disappears, and the solid particles are easily fluidized as a dry simple substance. Then, the fluidized solid particles collide with the heat transfer surface of the heat exchanger to destroy the temperature boundary layer. In this way, it is possible to prevent solid particles from sticking to each other due to moisture and solidifying, and moreover, since the speed of the air flow is uniform regardless of the location, the thermal conductivity is improved and uniformed,
The heat exchange rate is improved. By using a honeycomb-shaped ceramic heater as the heating means, it is possible to integrally manufacture the heater.
For example, the design and manufacturing becomes easier as compared with the case of using a nichrome wire or the like.

[0006]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a sectional view of an embodiment of the present invention.
This fluidized bed heat exchanger is obtained by adding a honeycomb-shaped ceramic heater (hereinafter, simply referred to as a heater) 7 as shown in FIG. 2 to the conventional example shown in FIG. This heater 7
Is fixed to the casing 1 below the net filter 3 which is a perforated plate member. The shape and size of the hole are determined so that the velocity of the wind passing therethrough is uniform (rectified) regardless of the place where the wind passes. Further, since the material is ceramic, it can be integrally formed, and the design and manufacture are easy. Further, the net filter 3 has a lattice shape, and the size of the holes is smaller than the size of the solid particles, so that the air sent from below is passed and the solid particles are prevented from falling.

The wind sent from the blower 5 enters the casing 1 as shown by the arrow, is rectified through the heater 7, passes through the net filter 3, and hits the solid particle layer 4 to reach the solid particle layer 4 Is fluidized (the layer of fluidized solid particles is referred to as a fluidized bed) to raise the solid particles. The solid particles 6 floated by this wind pressure pass between the pipes 2a and the fins 2b of the heat exchanger 2, and collide with the surfaces of the pipes 2a and the fins 2b during this passage,
The collision energy destroys the temperature boundary layer and significantly improves the thermal conductivity. Further, by uniformizing the wind speed regardless of the location, the thermal conductivity of the heat exchanger 2 is averaged over the whole, and the heat exchange rate is improved. Further, as described in the conventional example, when the heat exchanger 2 is used for heat exchange between the air flow and the low temperature medium, the water droplets adhering to the surfaces of the pipes 2a and the fins 2b are transferred by the floating solid particles 6. Since it is blown off from the surface of the hot surface, it is possible to prevent a decrease in thermal conductivity due to the attachment of water droplets. Further, when the water in the air flow or the water blown off by the solid particles 6 and dropped adheres to the solid particles and the solid particles adhere to each other to solidify the fluidized bed 4 and increase the pressure loss, the heater is used. It is good to energize 7. By doing so, the wind from the blower 5 is heated by the heater 7 to become warm air, passes through the net filter 3 and hits the layer 4 of solid particles to evaporate the moisture between the solid particles and separate the bonds of the solid particles. Since the layer 4 is fluidized, it is possible to prevent a decrease in thermal conductivity due to solidification of the fluidized layer 4. In addition, by keeping the heater 7 always energized, it is possible to prevent the fluidized bed 4 from always warming and solidifying.

[0008]

As is apparent from the above, the fluidized bed heat exchanger according to the present invention is provided below the heat exchanger and below the perforated plate-like member on which the layer of solid particles is placed. The airflow has a shape in which the velocity of the airflow is uniform regardless of where it passes, and since the heating means for heating the airflow is provided, the velocity of the airflow passing through the heating means is The heat conductivity can be uniform regardless of where it passes, and the moisture between the solid particles can be evaporated by the air flow heated by the heating means to prevent the solid particles from adhering to each other and solidifying due to the moisture. And the heat exchange rate can be significantly improved. Further, the above heating means can be integrally manufactured by using a honeycomb-shaped ceramic heater, which facilitates design and manufacturing as compared with a case where the heating means is constituted by, for example, a nichrome wire.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a partial perspective view of a honeycomb-shaped ceramic heater in the above embodiment.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

1 ... Casing, 2 ... Heat exchanger, 3 ... Net filter,
4 ... Layer of solid particles (fluidized bed), 5 ... Blower, 6 ... Blown solid particles, 7 ... Honeycomb-shaped ceramic heater.

Claims (2)

[Claims] 1. A heat exchanger is provided in a passage of an air flow from a lower side to an upper side, and a perforated plate-like member on which a layer of solid particles is placed is provided below the heat exchanger, and the solid particles are provided by the air flow. In a fluidized bed heat exchanger in which the solid particles are fluidized to collide the solid particles with the heat transfer surface of the heat exchanger to destroy the temperature boundary layer of the heat exchanger, A fluidized bed heat characterized by having a heating means for heating the passing airflow, which has a shape that allows the airflow to pass therethrough and has a uniform velocity regardless of where the passing airflow passes. Exchanger. 2. The fluidized bed heat exchanger according to claim 1, wherein the heating means is a honeycomb ceramic heater.