JPH08128726A - Waste water heat recovery system - Google Patents

Abstract

PURPOSE: To improve the hot-wastewater heat recovery rate and the precision in measuring the water flow rate by a method wherein the supply water flow rate is controlled according to the hot-water level in a hot-water storage tank, and controls are carried out so that hot-wastewater in a hot-wastewater tank is pumped and sent to a hot-wastewater heat recovery device at a flow rate in a specified proportion to the supply water flow rate that is controlled. CONSTITUTION: A flow control valve 14 is installed on a supply water line 3 leading from a water storage tank 1 to a heat source device 2 via a hot- wastewater heat recovery device 6. Two or more hot-water level sensors 10 are arranged in a hot-water storage tank 9 where hot-water heated by the heat source device 2 is stored. In addition, hot-wastewater is once stored in the hot-water storage tank 9 and then pumped and discharged by a hot- wastewater pump 12 via the hot-wastewater heat recovery device 6. The flow control valve 14 is controlled according to the water levels detected by the hot-water level sensors 10 and the hot-wastewater pump 12 is controlled by a flow controller 15 so that hot-wastewater in a hot-wastewater tank 11 is pumped and sent to the hot-wastewater heat recovery device 6 at a flow rate equivalent to 70-100% of the supply water flow rate that is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste water heat recovery system installed in public baths and the like.

[0002]

2. Description of the Related Art FIG. 3 shows a waste water heat recovery system installed in a public bath, in which a water supply line 3 from a water tank 1 to a heat source device 2 and a waste water line 5 from a washing place 4 are provided on the way. By crossing with the waste water heat recovery device (heat exchanger) 6,
The waste water heat recovery device 6 is configured to give heat to waste water to the water flowing through the water supply line 3, and the waste water heat recovery device 6 is attached to the water supply line 3 by passing the water supply line 3 through a wooden frame 7 as shown in FIG. The heat transfer area is secured by the metal plate (plate) 8. The conventional waste water heat recovery device 6 is usually installed under the floor or underground, and the overall heat transfer coefficient during heat exchange is about 100 [kcal / ° C · m ² hr].

[0003]

However, the above-mentioned conventional waste water heat recovery system has the following drawbacks. a. Since the overall heat transfer coefficient is very small, it is necessary to increase the size of the waste water heat recovery device 6 in order to increase this coefficient, and the heat dissipation area to the ground becomes large. b. Currently, only 50% or less of the heat quantity of waste water heat is recovered. c. In order to effectively recover the heat of the waste water, it is necessary that the water supply and the waste water simultaneously flow at substantially the same flow rate. However, in the conventional configuration, the amount of waste water is large compared to the amount of water supply, and waste water is discharged as waste heat loss, or conversely, the amount of water supply may flow when the amount of waste water is small. Also,
Depending on the operation example, only one of them may flow and heat exchange may not be performed. d. The overall heat transfer coefficient during heat exchange is 100 as described above.
It is about [kcal / ℃ ・ m ² hr], which is very small.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and the constitution thereof is as follows. 1. A flow control valve was attached to the water supply line from the water storage tank to the heat source device via the waste water heat recovery device, and for detecting multiple water levels in the hot water tank that stores hot water heated by the heat source device. A hot water storage water level sensor is attached, the waste water is temporarily stored in the waste water tank and then pumped up using a waste water pump, and is drained via the waste water heat recovery device. The waste water heat recovery device controls the flow rate control valve in accordance with the water level detected by the hot water storage water level sensor, and pumps up 70 to 100% of the waste water volume controlled by the flow rate control valve from the waste hot water tank. A waste hot water heat recovery system, characterized in that a controller for controlling the waste hot water pump is provided so as to be fed into the waste hot water heat recovery system. 2. In 1 above, a water level sensor is installed in the waste water tank to detect the water level in the waste water tank, and when the water level falls below a specified level, pumping by the waste water pump is stopped and the water level rises above the specified water level. In some cases, the waste water heat recovery system is equipped with a safety circuit that controls pumping to prevent overflow, regardless of the water level in the hot water storage tank. 3. 2. The waste hot water heat recovery system according to 1 or 2 above, which uses a plate heat exchanger as the waste hot water heat recovery device.

[0005]

When the water level in the hot water storage tank drops to, for example, a low water level, the controller opens the flow control valve to the maximum to supply water. At the same time, the waste water pump is maximally driven to control the maximum amount of waste water pumped up. Table 1 shows an example of this control.

[0006]

[Table 1]

Since the waste water from the washing place is not constant each time, the waste water is temporarily stored in the waste water tank, and is then pumped up by the waste water pump and discharged. The water flowing through the water supply line and the waste water flowing through the waste water line intersect at the waste water heat recovery device, heat is transferred from the waste water side to the water supply side, and the temperature of the water supply rises. This heated water reaches the heat source machine and is heated,
For example, the water is once stored in a hot water storage tank, and hot water is supplied from here to the faucet of the bathtub or the washing area. In the above control, the waste water pump is controlled so as to have a ratio of 70 to 100% with respect to the amount of water supplied through the waste water heat recovery device. Further, when the heat source device is not driven (when there is no water supply), the controller temporarily stops the waste water pump and stores the waste water in the waste water tank, and waste heat is not recovered. Prevent. However, the waste water pump is stopped when the water level sensor in the waste water tank detects the amount of water below the regulation, and in the above cases, the waste water pump is driven to perform control for overflow prevention.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which 1 is a water tank, 2 is a heat source device, 3 is a water supply line, 4 is a washing place, and 5 and 5.
a is a waste hot water line, 6 is a waste hot water heat recovery device (plate type heat exchanger), 9 is a hot water storage tank, and 10 is a hot water storage water level sensor attached to the hot water storage tank 9. It is possible to detect water levels at three low levels. 11 is waste water line 5
A waste water tank for temporarily collecting the waste hot water from the above, a waste water pump 12 for discharging the once stored waste hot water through the waste hot water heat recovery device 6, and a reference numeral 13 attached to the waste hot water tank 11. A water level sensor 14 is a control valve attached to the water supply line 3, and the control valve 14 can perform three-stage control of full open, medium open, and small open. Reference numeral 15 is a controller.

The water level in the hot water storage tank 1 is detected by the hot water level sensor 10, and when the detected water level is low, the controller 15 controls the control valve 14 to be fully opened, and at the same time, the waste water pump 12 is set to the maximum. Control valve 1 when driven and the water level is medium
4 Medium / waste water pump 12 Medium / high water level control valve 1
4 Small opening / waste water pump 12 is controlled to low. The waste hot water from the washing place 4 is temporarily stored in the waste hot water tank 11, is then pumped up by the waste hot water pump 12, and is drained from the waste hot water line 5a. The water flowing through the water supply line 3 and the waste hot water flowing through the waste hot water line 5a intersect at the waste hot water heat recovery device 6, heat is transferred from the waste hot water side to the water supply side, and the temperature of the water supply rises. The heated water reaches the heat source device 2, is heated, is temporarily stored in the hot water storage tank 9, and is supplied to the faucet of the bathtub or the washing place from here.

In the above-mentioned water supply and waste water flows, the amount of water flowing through the waste water line 5 is controlled to 70 to 100% in all three levels with respect to the amount of water flowing through the hot water supply line 3. Next, when there is no flow in the water supply line 3, the controller 15 temporarily stops the waste water pump 12 and stores the waste water in the waste water tank 11.
Prevent waste water from being recovered without recovering heat. However, when the water level sensor 13 in the waste water tank 11 detects the water level below the specified level, the waste water pump 12 is temporarily stopped. Drive to prevent overflow. FIG. 2 shows an example of a plate heat exchanger used as the waste hot water heat recovery device 6, in which 6a is a plate fin, 6b is a feed water inlet / outlet, and 6c is a waste hot water inlet / outlet.

[0011]

The effects of the present invention are as follows. a. Since the water supply and waste water flow in the waste water heat recovery device at the same time,
It is possible to raise the waste water heat recovery rate to 70% or more. b. By using a plate heat exchanger, the overall heat transfer coefficient is 3000 times more than that of the conventional model, 3000 [kcal / ℃ ・ m ² h
r]. c. By using a system with higher efficiency than the conventional type, it is possible to construct an energy-saving and earth-friendly system. d. By measuring the water supply with a water supply meter, it is possible to measure the water supply with high accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a plate heat exchanger.

FIG. 3 is an explanatory view of a conventional waste water heat recovery system.

FIG. 4 is an explanatory view of a waste water heat recovery device having a conventional wooden frame structure.

[Explanation of symbols]

 1 Water Supply Tank 2 Heat Source Machine 3 Water Supply Line 4 Washing Station 5, 5a Waste Hot Water Line 6 Waste Hot Water Heat Recovery Device 9 Hot Water Storage Tank 10 Hot Water Storage Level Sensor 11 Waste Hot Water Tank 12 Waste Hot Water Pump 13 Water Level Sensor 14 Flow Control Valve 15 Controller

Claims (3)

[Claims] 1. A flow control valve is attached to a water supply line from a water storage tank to a heat source device via a waste water heat recovery device, and a plurality of water levels are stored in the hot water tank for storing hot water heated by the heat source device. A hot-water storage water level sensor was installed to detect that the waste water was once stored in the waste-water tank and was then pumped up using the waste-water pump, which was then drained via the waste-water heat collector. The flow control valve is controlled according to the water level detected by the hot water storage water level sensor, and 70 to 100% of the amount of water controlled by the flow control valve is pumped up from the waste water tank. A waste water heat recovery system, characterized in that a controller for controlling the waste water pump is provided so as to be fed into the waste water heat recovery device. 2. The method according to claim 1, wherein a water level sensor is installed in the waste water tank to detect the water level in the waste water tank, and when the water level falls below a prescribed level, pumping by the waste water pump is stopped, A waste hot water heat recovery system that is equipped with a safety circuit that controls pumping to prevent overflow when the water level rises above the specified level regardless of the water level in the hot water storage tank. 3. The waste hot water heat recovery system according to claim 1, wherein a plate heat exchanger is used as the waste hot water heat recoverer.