JPH0849916A - Exhaust heat recovery system - Google Patents

Abstract

PURPOSE:To save the fuel by recovering the exhaust gas loss heat of a steam boiler. CONSTITUTION:A latent heat recovery economizer 20 is added to a steam boiler 4, and water volume and temperature are detected and controlled by a storage water stage sensor 23 mounted at a storage hot water tank 5. When the boiler 4 is operated, a control valve 21 is opened to supply water a cold water line 9 of a water supply line to the economizer 20 to recover exhaust gas loss heat, thereby saving fuel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery system for fuel gas in public baths and the like.

[0002]

2. Description of the Related Art In recent public baths, a steam boiler is often used as a heat source machine. In the case of a steam boiler, city gas or heavy oil is often used as fuel, and an outline of an example of a public bath system using a steam boiler is shown in FIG.

In FIG. 2, 1 is a water supply line,
Most are supplied with tap water. 2 is a water receiving tank, 3 is a water treatment device, 4 is a steam boiler, 5 is a hot water storage tank, and a steam heat supplier 6 is incorporated in the hot water storage tank 5. Reference numeral 7 is an adjustment box, and 8 is an adjustment line connecting the adjustment box 7 and the hot water storage tank 5.

Reference numeral 9 denotes a cold water line, which is constructed such that well water is pumped up to a high water tank 11 by a pump 10 and supplied to the hot water storage tank 5 and the adjusting box 7.

Reference numeral 12 is a heat drainage line. A waste water heat recovery unit 13 is attached to this heat drainage line 12, and water flowing in the water supply line 9 from the above-mentioned elevated water tank 11 to the adjustment box 7 is introduced. Is a structure in which the waste water heat recovery device 13 recovers heat from the hot waste water and warms it. In the figure, 14 is a bath line to the bath heat exchanger, and 15 is a sauna line to the sauna.

[0006]

As described above, even in the conventional public bath, it is devised to save the fuel (resource saving) by recovering the exhaust heat from the hot waste water by the waste water heat recovery device 13. However, it has the following drawbacks.

A. Generally, the system efficiency of the hot water / steam system is not high, and much heat is wasted. For example, particularly in the case of public baths, for the amount of combustion is very large, this situation is not only a waste of energy, which is responsible of the NO _x and global warming is the cause of acid rain in the exhaust gas CO ₂ Therefore, it is a problem in the global environment.

B. The equipment efficiency of a normal steam boiler is about 80%
(Higher heating value standard). There are also known examples of devising the recovery of waste heat from this combustion exhaust gas, like some steam boilers, but the latent heat utilization, which is an effective use of exhaust heat, is not sufficiently performed and is wasted as exhaust loss. It's gone. The reason for this is that in a steam boiler, it takes several 1
Boiler heat output shown in is required.

[Equation 1] At that time, as exhaust gas loss, exhaust gas heat shown in Formula 2 is discharged.

[Equation 2] Therefore, even if it is attempted to recover heat from the exhaust gas loss of 155 kcal with water at 20 ° C. and 1 kg supplied to the steam boiler,
This is because the water temperature rises to the dew point of the exhaust gas (a little less than 60 ° C. in the case of natural gas), and latent heat recovery is impossible.

An object of the present invention is to contribute to fuel saving and global environmental conservation by recovering exhaust gas loss (including latent heat) of a steam boiler in a steam boiler system in public baths and the like. It is to be.

[0010]

The structure of the exhaust heat recovery system according to the present invention is as follows. A latent heat recovery economizer was attached to the steam boiler for heating the water in the hot water tank, and a water supply line with a water tank to the steam boiler was provided, and a cold water line of a system different from this water supply line was provided, This cold water line is configured to reach the hot water storage tank via the latent heat recovery economizer, a water storage amount adjusting device for adjusting the water storage amount of the water storage tank of the water supply line is provided, and a control valve is provided in the cold water line. And a control circuit for adjusting the amount of water stored in the water receiving tank by the water storage adjusting device and controlling the control valve when the steam boiler is operating to generate running water in the cold water line. Exhaust heat recovery system.

[0011]

[Function] The water supplied from the water supply line is heated by, for example, a steam boiler that uses city gas as fuel, becomes steam, and is supplied to the steam heat exchanger in the hot water tank, where the water in the hot water tank is heated. Give and condense.

On the other hand, the water supplied from the cold water line of a system different from the water supply line reaches the latent heat recovery economizer. The control circuit detects the amount of water in the hot water storage tank by the water storage amount detection device, and controls the cold water to flow by opening the control valve of the cold water line when the steam boiler is operating. At this time, as described above, it is impossible to sufficiently recover the heat from the exhaust heat loss even if the water in the supply line that supplies water to the steam boiler is used. It is possible to collect even. The cold water line that recovers heat from the exhaust heat loss of the steam boiler reaches the hot water tank.

[0013]

EXAMPLE FIG. 1 shows an example in which the present invention is applied to a public bathhouse. In FIG. 1, reference numeral 1 is a water supply line, which is a line for supplying water to the steam boiler. Since the durability of the steam boiler is affected by the water quality, tap water is mostly supplied, but it is not limited to this. 2 is a water tank,
3 is a water treatment device, 4 is a steam boiler, 5 is a hot water storage tank,
A steam heat supplier 6 is incorporated in the hot water storage tank 5. Reference numeral 7 is an adjusting box, and 8 is an adjusting line connecting the adjusting box 7 and the hot water storage tank.

Reference numeral 9 denotes a cold water line, which is often constructed such that well water is pumped up to the elevated water tank 11 by the pump 10 and supplied to the adjusting box 7.

Reference numeral 12 denotes a heat drainage line from the bathhouse, and a waste heat recovery unit 13 is attached to this heat drainage line 12, and the inside of the water supply line 9 from the above-mentioned elevated water tank 11 to the control box 7 is The flowing water has a configuration in which latent heat is recovered from the warm heat drainage and warmed by the waste heat recovery device 13. In the figure, 14 is a bath line to the bath heat exchanger, and 15 is a sauna line to the sauna.

Reference numeral 20 denotes a latent heat recovery economizer attached to the steam boiler 4, and the cold water line 9 passing through the waste heat recovery device 13 passes through the latent heat recovery economizer 20.
From the control valve 21 to the hot water storage tank 5 via the line 9a.

Reference numeral 22 is a control circuit.
2 monitors the amount and temperature of water in the hot water tank 5 and the operating state of the steam boiler 4 by means of the water storage state (temperature and water amount) detection device 23, and does not always keep the amount of water in the hot water tank 5 full. Properly control so that only the required amount of hot water is stored. By doing so, when the steam boiler 4 is in operation, the control valve 21 is opened to allow water to flow to the latent heat recovery economizer 20, and exhaust gas loss heat can be recovered. Naturally, hot water storage tank 5
Depending on the temperature and the amount of water, the control valve 21 is opened to allow water to flow even when the steam boiler 4 is not operating.

The present system relates to an exhaust gas heat recovery system for a steam boiler, and is not limited to a hot water system for public baths.

[0019]

As described above, according to the present invention, the latent heat recovery economizer is attached to the steam boiler, and the control circuit detects the water amount and temperature of the hot water storage tank by the water storage state detection device, and the latent heat recovery economizer is operated during the steam boiler operation. By passing water, the exhaust gas heat loss of the steam boiler can be effectively recovered. Therefore, according to the present invention, combustion costs can be saved in a steam boiler system such as a public bathhouse.
In addition, the amount of exhaust gas containing NO _x and CO ₂ can be reduced,
Contribute to environmental issues.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment when the present invention is applied to an exhaust heat recovery system in a public bath.

FIG. 2 is an explanatory view of a conventional exhaust heat recovery system in a public bath.

[Explanation of symbols]

 1 Water supply line 2 Water receiving tank 3 Water treatment device 4 Steam boiler 5 Hot water storage tank 6 Steam heat exchanger 7 Control box 8 Control line 9 Cold water line 10 Pump 11 High water tank 12 Heat heat drain line 13 Waste heat recovery unit 14 Bath line 15 Sauna Line 20 Latent heat recovery economizer 21 Control valve 22 Control circuit 23 Water storage adjustment device

Claims (1)

[Claims] 1. A steam boiler for heating water in a hot water storage tank is provided with a latent heat recovery economizer, and a water supply line with a water storage tank leading to the steam boiler is provided, and cold water of a system different from this water supply line is provided. A line is provided, and this cold water line is configured to reach the hot water storage tank via the latent heat recovery economizer, and a water storage amount adjusting device for adjusting the water storage amount of the water storage tank of the water supply line is provided, A control valve is attached to the cold water line, and by the water storage amount adjusting device, the water storage amount of the water receiving tank is adjusted,
An exhaust heat recovery system comprising a control circuit for controlling the control valve to generate running water in a cold water line when the steam boiler is in operation.