JPS59210262A - Warm air heater - Google Patents

Abstract

PURPOSE:To improve the heat exchanging efficiency of the warm air heater by cooling exhaust gas to a temperature lower than a dew point through a secondary heat exchanger. CONSTITUTION:The exhaust gas is collected into an exhaust gas box 6 once, thereafter, is flowed through a plurality of tubes, constituting the secondary heat 5 consisting the after stage of a heat exchanger 3, from the upper parts to the lower parts thereof. Airflow is collided against the secondary heat exchanger 5 forcibly, whereby the temperature of the exhaust gas, passed therethrough, becomes lower than the dew point, water vapor in the exhaust gas is condensed into dew water and is reserved into a drain tank 8. Thereafter, the exhaust gas is passed through the exhaust gas box 6 located in a comparatively high temperature zone to heat it slightly. According to the heating, the exhaust gas obtains a margin with respect to the dew point and, therefore, moisture condensation on the way of the exhaust tube 4 may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a forced air supply/exhaust type hot air heater, and aims to improve its heat exchange efficiency.

The general configuration of a forced air supply/exhaust type combustion machine is to introduce outdoor air, combust it, exchange heat with indoor air, and then exhaust the air outdoors again. In recent years, there has been a tendency for thermal efficiency to become higher and higher in response to market demands. When the temperature difference between the supply air temperature and the exhaust air temperature becomes 0, the efficiency becomes 100%, but in reality, 92 to 93% is considered to be almost the limit. One of the reasons is that in order to increase thermal efficiency, the exhaust temperature must be lowered.

Whether it's liquid fuel or gaseous fuel.

The combustion product contains water vapor, and when the exhaust gas reaches the dew point, the water vapor condenses and corrodes the exhaust pipe.
Depending on the temperature, it may freeze inside the pipes, blocking the outflow of combustion air. Therefore, as a means to prevent this, it was necessary to maintain the exhaust gas temperature above a certain value, which was a key factor in improving thermal efficiency.

The present invention eliminates the above-mentioned drawbacks, makes it possible to bring the thermal efficiency close to 10%, and furthermore prevents dew condensation or freezing in the exhaust pipe. An embodiment will be explained below based on the drawings.

The figure is a configuration diagram of an embodiment of the present invention, and in the figure,
Reference numeral 1 denotes a liquid combustion burner, such as a rotary path type burner, which has a built-in blower for air supply and exhaust.

2 is a combustion tube, and 3 is a heat exchanger consisting of a plurality of tubes, through which the combustion exhaust gas flows, and at the same time exchanges heat with indoor air by blowing air from a hot air blower (not shown), and then flows into the room. The exhaust gas is discharged as warm air to lower the temperature of the exhaust gas, and in conventional equipment, it is common to exhaust the exhaust gas outdoors through the exhaust pipe 4 at this stage.

At this time, the exhaust gas temperature had to be kept above the dew point as described above. 51d, a secondary heat exchanger which forms the latter stage of the heat exchanger 3, in which the exhaust gas is collected in the exhaust bonox 6 and then passed upward through the plurality of tubes constituting the secondary heat exchanger 6; It flows downward from the top. By forcibly applying air to this secondary heat exchanger 6, the temperature of the exhaust gas passing through it is kept below the dew point, and a trap is installed to condense water vapor in the exhaust gas and release it into dew water. It passes through the water pipe 7 and is stored in the drain tank 8. Reference numeral 9 is a pump that sends this dew condensation water to the humidifying dish 1o, and 11 is a switching valve that switches the water supply channel to the outdoor water discharge pipe 13 in response to a signal from a water level detector 12 provided in the drain tank 8.

In this way, the two-stage heat exchangers 3 and 5 lower the exhaust temperature and not only exchange sensible heat with room temperature, but also obtain some of the latent heat by condensing water, resulting in The same heating effect can be achieved even if the combustion amount is reduced, resulting in fuel savings. On the other hand, since the exhaust gas temperature exchanges heat with the indoor air in the membrane layer, even if the outside air is below freezing, it may be further cooled in the exhaust pipe 4. After condensation water is condensed as the temperature drops, the exhaust gas has reached saturated water vapor, and if the temperature drops even a little, it will immediately condense. Therefore, in order to prevent this, the exhaust gas is passed through the exhaust box 6, which is in a relatively high temperature region, and is slightly heated.

This creates a margin for the dew point of the exhaust gas, and can prevent dew condensation in the middle of the exhaust pipe. Moreover, the high-temperature exhaust gas in the exhaust box 6 also loses heat through heat exchange with this low-temperature exhaust gas, so the exchange load on the secondary heat exchanger 6 is reduced by that amount, so the secondary heat It is also possible to make the exchanger 6 relatively compact.

As described above, the present invention cools exhaust gas below its dew point through a heat exchanger, and uses the resulting dew condensation water for indoor humidification, etc., thereby converting not only sensible heat but also a portion of latent heat indoors. By heating the exhaust gas again in the exhaust box to prevent condensation during the process of releasing the exhaust gas outdoors, it is possible to prevent condensation and freezing in the exhaust pipe, making it extremely practical. It will be rich in Also, if the fuel contains moisture in the exhaust gas,
It has a wide range of applications, as the same effect can be obtained with the same composition whether it is a liquid or a gas.

[Brief explanation of the drawing]

The figure is a configuration diagram of a hot air heater according to an embodiment of the present invention. 3...Heat exchanger, 6...Secondary heat exchanger, 6...Exhaust box. Name of agent: Patent attorney Toshio Nakao and 1 other person1

Claims (1)

[Claims] This hot air heater is configured to cool combustion exhaust gas containing water vapor to below the dew point using a heat exchanger, remove some of the condensed water, and then pass it through the high-temperature exhaust box again before releasing it outdoors.