JP2004163048A - Air heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an air heating apparatus for preventing condensate from residing inside a heat exchanger. <P>SOLUTION: A steam supply pipe 2 is connected to an inlet header 8 of the heat exchanger 1. A compressed air supply pipe 4 is connected to the side of the inlet header 8 in a steam supply pipe 2. A steam trap 5 is connected to an outlet header 9 of the heat exchanger 1. An on/off valve 6 is mounted in parallel with the steam trap 5. A condensate residence detection means 11 is mounted to the bottom section of the outlet header 9. The condensate residing in the heat exchanger 1 is pushed out and is removed by high-pressure compressed air supplied from the compressed air supply pipe 4, thus the condensate is prevented from residing inside. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an air heating device that heats air using steam as a heat source, and more particularly to an air heating device that does not accumulate condensed water as steam condensed water inside the heating device.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Publication No. 51-31998 discloses an air heating apparatus using a fin tube type heat exchanger, in which the amount of steam supplied to the heating apparatus is controlled by an adjusting valve and the heating apparatus is checked. The valve and the thermal valve are used in combination to prevent the check valve from opening when the inside of the heating device is evacuated and sucking outside air into the heating device to prevent the condensate from being discharged.
[0003]
[Problems to be solved by the invention]
The conventional air heating device has a problem that the condensate in the heating device cannot be completely discharged. That is, when the inside of the heating device becomes a vacuum, the outside air is sucked in, and the differential pressure between the inlet side and the outlet side of the steam trap for discharging the condensate can be prevented from becoming a negative pressure. The pressure on the outlet side is both atmospheric pressure and the substantial differential pressure remains zero, and condensate remaining in the concave portion or the thin tube portion inside the heating device cannot be discharged to the outside.
[0004]
If the condensed water stays inside the heating device, a water hammer phenomenon occurs, the inside of the heating device is corroded, and in some cases, the fin tube is opened and damaged.
[0005]
Accordingly, an object of the present invention is to provide an air heating device that does not cause condensate to stay inside even during operation of the heating device.
[0006]
[Means for Solving the Problems]
Means for solving the above problem is to heat air passing through the heat exchanger with heating steam supplied through a control valve, and to condensate condensed by the steam being deprived of heat by a steam trap. In the case of exhausting water from the outside, an on-off valve was installed in parallel with the steam trap, a compressed air supply pipe for supplying compressed air to the inside of the heat exchanger was connected, and condensate remained inside the heat exchanger The condensate retention detecting means for detecting the above is attached, and compressed air is supplied from the compressed air supply pipe to the inside of the heat exchanger according to a detection signal from the condensate retention detection means.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The condensate retention detecting means detects that condensate has accumulated inside the heat exchanger, opens the on-off valve attached in parallel with the steam trap, and compresses the compressed air supply pipe into the heat exchanger. By supplying the air, the condensate remaining in the concave portion or the narrow tube portion inside the heat exchanger is pushed out by the compressed air and is reliably removed to the outside.
[0008]
【Example】
In this embodiment, a heat exchanger 1 for heating the passing air, a steam supply pipe 2 for supplying steam to the heat exchanger 1, a control valve 3 attached to the steam supply pipe 2, A compressed air supply pipe 4 connected to the inlet side, a steam trap 5 connected to the outlet side of the heat exchanger 1, an on-off valve 6 mounted in parallel with the steam trap 5, and a bottom part of the heat exchanger 1. An air heating device is constituted by the condensate retention detecting means 11 and the vacuum pump 7 connected to the steam trap 5 and the outlet side of the on-off valve 6.
[0009]
An inlet header 8 is arranged on the left side of the heat exchanger 1 and connected to the steam supply pipe 2, and an outlet header 9 is arranged on the right side and connected to the steam trap 5. The steam supplied from the steam supply pipe 2 passes through the entire fin tube (not shown) in the heat exchanger 1 from the inlet header 8, exchanges heat with air to be condensed, and flows through the steam trap 5 from the outlet header 9. Then, it is sucked by the vacuum pump 7 and discharged to the outside.
[0010]
A control valve 10 for controlling the amount of compressed air to be supplied is attached to the compressed air supply pipe 4. In this embodiment, an example is shown in which the compressed air supply pipe 4 is connected to the heat exchanger 1 side of the steam supply pipe 2, but the compressed air supply pipe 4 can be connected to the upper end of the inlet header 8.
[0011]
The condensate retention detecting means 11 is attached to the bottom of the outlet header 9. The condensate retention detecting means 11 is capable of detecting condensate retained at the bottom of the outlet header 9. For example, the condensate retention detector 11 may be provided with an electrode rod to detect and detect the difference in electrical conductivity between condensate and steam, A sensor that detects and detects a temperature difference between steam and condensate by a sensor can be used.
[0012]
At the upper end of the outlet header 9, a temperature sensing valve 12 that detects the temperature inside the header 9 and opens and closes the valve is attached. The temperature sensing valve 12 automatically opens and discharges air to the outside when air accumulates inside the header 9 and the temperature drops to a predetermined value, and closes automatically when the internal temperature rises to a predetermined value. To prevent leakage of steam.
[0013]
The condensate retention detecting means 11, the control valves 3, 10 and the on-off valve 6 are connected to a control unit (not shown), and the valve opening or the opening / closing of the valve is automatically controlled according to a signal from the control unit. It is.
[0014]
When air is heated by the heat exchanger 1, the air flowing down the heat exchanger 1 is heated by steam at a predetermined pressure supplied from the steam supply pipe 2 and the inlet header 8. The steam deprived of heat by heating becomes condensed water and is removed from the steam trap 5 and the vacuum pump 7 to the outside of the system.
[0015]
When the condensate retention detecting means 11 detects condensate retention in the outlet header 9, it opens the on-off valve 6 and supplies compressed air of a predetermined pressure from the control valve 10 to the inside of the heat exchanger 1. As a result, the condensate remaining in the lower portion, the concave portion, the narrow tube portion or the like in the heat exchanger 1 is reliably pushed out to the outside through the on-off valve 6 and the vacuum pump 7 and remains in the heat exchanger 1. Never.
[0016]
When the condensate is eliminated, the supply of the compressed air is stopped, and the steam is again supplied from the steam supply pipe, whereby the compressed air in the heat exchanger 1 is pushed out of the on-off valve 6 to the outside by the steam. When the compressed air is removed, the on-off valve 6 is closed to perform normal air heating.
[0017]
In the present embodiment, an example is shown in which the vacuum pump 7 is connected to the outlet side of the steam trap 5 and the on-off valve 6. However, when the condensed condensate can be reliably removed only by the compressed air from the compressed air supply pipe 4. Does not necessarily require the vacuum pump 7.
[0018]
【The invention's effect】
According to the present invention, by supplying compressed air to the inside of the heat exchanger, it is possible to reliably discharge residual condensate inside the heating device to the outside even during operation of the heat exchanger.
[Brief description of the drawings]
FIG.
FIG. 1 is a configuration diagram illustrating an embodiment of an air heating device according to the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 heat exchanger 2 steam supply pipe 3 control valve 4 compressed air supply pipe 5 steam trap 6 on-off valve 8 inlet header 9 outlet header 11 condensate retention detecting means

Claims (1)

The air passing through the heat exchanger is heated by heating steam supplied through a control valve, and steam is deprived of heat and condensed water is discharged from the steam trap to the outside. Attach an on-off valve in parallel, connect a compressed air supply pipe that supplies compressed air to the inside of the heat exchanger, and attach condensate retention detecting means to detect that condensate has accumulated inside the heat exchanger. And supplying compressed air from the compressed air supply pipe to the inside of the heat exchanger according to a detection signal from the condensate retention detecting means.

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