JP4279981B2 - Water heater - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a water heater provided with a heat exchanger that heats water through combustion heat.
[0002]
[Prior art]
Conventionally, a water heater includes a heat exchanger to which a water supply pipe and a hot water discharge pipe are connected, a burner that heats the heat exchanger, and a fan that supplies combustion air to the burner. In general, a forced-combustion water heater is known that heats water through and discharges water from a tapping pipe.
Among such water heaters, there is a latent heat recovery type water heater that condenses water vapor in combustion exhaust generated from a burner in a heat exchanger to recover the latent heat in order to improve thermal efficiency.
[0003]
[Problems to be solved by the invention]
However, the condensed drain reacts with sulfur (S) and nitrogen (N) in the combustion exhaust gas and becomes acidic at about pH 3, and may deviate from the wastewater standards (for example, pH 5-9) set by local governments. As it was, it could not be discharged into a general drainage passage such as a sewer.
[0004]
Therefore, it is necessary to neutralize the acid drain using a neutralizing agent such as magnesium or calcium carbonate, or mix it with a large amount of water from the water supply and dilute it to reduce the acidity before draining it. did not become.
However, when a neutralizing agent is used, in consideration of the general useful life of the instrument (for example, 10 years), a considerably large device is required, and the neutralizing device alone becomes very expensive.
In addition, when diluting with tap water, it is necessary to supply water more than 100 times the amount of drain to the diluting device provided in the water heater, and in addition to increasing the size of the vessel, water bills are also required. It takes quite a while and is not practical as a solution.
Then, the hot water heater of this invention solves the said subject, and aims at discharging | emitting to a general drainage path after raising pH of drain to a safe level at low cost.
[0005]
[Means for Solving the Problems]
The water heater according to claim 1 of the present invention for solving the above problems is
In a water heater provided with a heat exchanger that heats water through the combustion heat of the burner and collects latent heat in the combustion exhaust, and a drain passage that discharges the drain generated in the heat exchanger to the outside of the body,
The drain passage is connected to a drain pipe outside the water heater that discharges hot water waste water after the hot water from the heat exchanger is used to the general drain passage ,
A flow rate sensor for detecting the flow rate of hot water drainage is provided at a position upstream from the connection portion of the drainage pipe with the drain passage,
In the drain passage, in order from the upstream, a drain reservoir for storing drain, and an on-off valve for opening and closing the drain passage,
When the flow rate sensor detects a hot water supply / drainage flow rate of a predetermined amount or more, the open / close valve is opened at an opening corresponding to the detected hot water supply / drainage flow rate, and the drain accumulated in the drain reservoir is mixed with the hot water supply wastewater. The gist is to discharge to the drainage passage .
[0007]
The water heater according to claim 1 of the present invention having the above-described configuration heats the heat exchanger with the combustion heat of the burner and heats the water with the heat conducted to the heat exchanger to supply hot water.
Hot water drainage used in hot water sources such as washrooms and kitchens is mixed with the drain generated in the heat exchanger and flowing in the drain passage when it flows in the drain pipe, and then discharged to the general drainage passage such as sewers and gutters. The That is, the hot water supply drainage and the drainage drainage are performed at the same timing, and the drain is diluted with the hot water supply wastewater. In this way, the acidity of the wastewater is at a safe level.
[0008]
Further , when the flow rate sensor detects that hot water or waste water of a predetermined flow rate or more is flowing in the drain pipe, the on-off valve provided downstream of the drain passage opens, and the drain accumulated in the upstream drain reservoir flows into the drain pipe.
In this way, since the drain is discharged only when the hot water drainage is discharged, the drain can be reliably diluted even when the hot water is temporarily stored.
For example, drainage is generated in the heat exchanger when hot water is added to the bathtub, but the hot water supplied to the bathtub is not immediately discharged to the drain pipe, so the open / close valve is closed and the drain remains undiluted. Preventing discharge to the general drainage passage through the drain pipe.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the water heater of the present invention will be described after describing the reference embodiment .
<< Reference Embodiment >>
A water heater as a reference embodiment will be described with reference to FIG.
The water heater 10 is provided at a lower position in the appliance main body 12 in a state where a heat exchanger 18 in which a water supply pipe 14 and a hot water discharge pipe 16 are disposed is mounted in the combustion chamber 20. Above the heat exchanger 18, a burner 22 for heating the heat exchanger 18 is provided via a mounting plate 24 with the burner flame hole side facing downward.
The appliance body 12 has an air supply port 30 for taking outside air as combustion air, and an exhaust port 44 above the air supply port 30.
[0010]
On the other hand, an exhaust hood 32 is provided at the lower end of the combustion chamber 20 that supports the heat exchanger 18 to discharge the combustion exhaust after the heat exchanger 18 is heated by the combustion exhaust of the burner 22. The exhaust hood 32 has a bowl shape with a large opening upward, and is connected to a drain passage 35 made of vinyl chloride below. The exhaust hood 32 also has a drain pan as a tray for receiving drain in the combustion exhaust.
An exhaust pipe 34 is connected to the side surface of the exhaust hood 32, and the upper end opening of the exhaust pipe 34 faces the exhaust port 44.
[0011]
Further, the heat exchanger 18 is provided with a plurality of stages meandering through the heat transfer tubes 18a through the fins 18b that absorb the combustion heat. The heat transfer pipe 18 a is connected to a water supply pipe 14 provided at the lower stage of the heat exchanger 18, wound around the combustion chamber 20, and connected to the hot water discharge pipe 16 in the vicinity of the burner 22.
The water supply pipe 14 is provided with a water-side control unit 50 including a water flow sensor and a water governor, and the gas pipe 52 to the burner 22 is provided with a main electromagnetic valve 54 and a gas proportional valve 56.
An air supply fan 36 is attached to the fan mounting base 38 on the burner cover 26 that covers the burner 22. A DC motor 48 is connected to the air supply fan 36.
[0012]
Further, the water flow sensor in the water-side control unit 50 provided in the water supply pipe 14, the main electromagnetic valve 54 and the gas proportional valve 56 provided in the gas pipe 52 of the burner 22, the DC motor 48, and the like are combusted by the water heater 10. Is electrically connected to a burner controller 58 for controlling the above.
[0013]
The hot water outlet pipe 16 of the water heater 10 is connected to a hot water supply pipe 60 extending to a bathroom, kitchen, or the like, and a hot water supply pipe 61 is provided at the tip of the hot water supply pipe 60. A drain passage 35 is connected to the drain pipe 65 connected to the wash basin 63 of the washroom and the sink 64 of the kitchen, and the tip of the drain pipe 65 communicates with a public sewer 66 (general drain passage). The drain passage 35 and the drain pipe 65 are privately owned in the home, and there is no restriction on the acidity of the drain.
[0014]
In the water heater 10 configured in this way, water (broken arrow in the figure) flows through the water supply pipe 14 by opening the hot water tap 61, and the burner controller 58 is detected by the detection signal from the water flow sensor in the water side control unit 50. A control operation is performed, and the air supply fan 36 starts to rotate when the DC motor 48 is driven. When the predetermined pre-purge is completed, the main electromagnetic valve 54 and the gas proportional valve 56 of the burner 22 are opened, gas (solid arrow in the figure) is supplied to the burner 22, and the burner 22 is ignited by an igniter (not shown).
[0015]
When the ignition operation is completed, proportional control is started, and if there is a difference between the hot water temperature detected by a hot water temperature thermistor (not shown) and a set temperature, the burner controller 58 determines that and sends a signal to the gas proportional valve 56, The outlet temperature of the heat exchanger 18 is kept constant by changing the gas amount continuously. Further, a signal is sent from the burner controller 58 to the DC motor 48 of the air supply fan 36 according to the change in the gas amount by the gas proportional valve 56, and the rotation speed of the air supply fan 36 is also changed. Is controlled to be kept constant.
[0016]
In such combustion control, along with the operation of the air supply fan 36, outside air is sucked into the instrument main body 12 from the air supply port 30 provided in the instrument main body 12, introduced into the burner 22, and used as combustion air for combustion. Is done.
In the vicinity of the flame opening of the burner 22, the air-fuel mixture burns to form a flame, and the combustion is completed (complete combustion) while reaching the upstream side of the heat exchanger 18.
The combustion exhaust of the burner 22 flows downward by the air supply fan 36 and flows through the fins 18b of the heat exchanger 18 to exchange heat, and then the exhaust from the exhaust port 44 through the exhaust hood 32 and the exhaust pipe 34. It is discharged outside.
[0017]
Water vapor in the combustion exhaust is cooled and condensed by heat exchange in the heat exchanger 18, and reacts with sulfur and nitrogen in the combustion exhaust to become acidic drain (H ₂ SO ₄ , HNO ₃ ).
Due to the condensation of the water vapor, the heat exchanger 18 collects latent heat of vaporization in addition to sensible heat to realize very high thermal efficiency.
[0018]
The acidic drain generated in the heat exchanger 18 falls into the exhaust hood 32 and flows to the drain pipe 65 through the drain passage 35. At this time, hot water is supplied from the hot-water tap 61, and hot water waste water after use is discharged from the sink 64 and the wash basin 63 to the drain pipe 65 at the same timing as discharge of the acid drain. Then, the acid drain is mixed with the hot water waste water in the drain pipe 65 and diluted to a safe pH level, and then discharged to the sewer 66.
As described above, since the hot water drainage and the acid drain drainage are performed simultaneously, the drain can be easily diluted with the hot water drainage without complicated control, and the acidity of the drainage is at a safe level.
Further, since the burner 22 is provided above the heat exchanger 18, even if acidic drain falls from the heat exchanger 18, the flame hole of the burner 22 is not clogged and a good combustion state is maintained. Is done.
[0019]
Next, the reason why the generated acid drain is sufficiently diluted to a safe level by the hot water drainage will be described.
For example, natural gas (13A) having a total calorific value of 10,991 kcal / Nm ³ and a true calorific value (sensible heat) of 9,923 kcal / Nm ³ in a water heater 10 with an input (gas supply amount) of 30,000 kcal / hour. Is used, the latent heat of vaporization is obtained as 1,068 kcal / Nm ³ by subtracting the true calorific value from the total calorific value.
[0020]
Here, in order to assume the case where drainage is generated to the maximum extent, it is assumed that latent heat is recovered and the thermal efficiency is 100%. Accordingly, since the latent heat is 9.7% of the total calorific value, it is 2,915 kcal / hour. Since it is known that the latent heat of vaporization of water (at 0 ° C.) is 597.1 kcal / kg, in this example, only 4.88 liters / hour of drain is generated.
In general, when NOx generated by a water heater is 60 ppm or less, it is known that the converted nitrate ion concentration of acidic drain is 70 mg / liter or less and the pH of acidic drain is 3 or more.
Therefore, in order to calculate the minimum amount of water necessary for dilution of acidic drain, it is necessary to consider the case where a maximum of 4.88 liters of acidic drain at pH 3 is generated per hour.
[0021]
In order to obtain the minimum amount of water that can be used to dilute the acid drain, it is only necessary to consider the case where the water heater 10 raises the temperature of the water flow most, in the case of heating water having a water temperature of 5 ° C. to 60 ° C. (that is, The temperature of water used at that time is 545 liters / hour (= 30,000 kcal / hour ÷ 55 cal / g).
[0022]
Therefore, the amount of water that can be used for diluting acidic drain is at least 112 times (= 545 / 4.88) the amount of acidic drain.
Therefore, the hydrogen ion concentration after dilution of acidic drain of pH 3 is 10 ⁻³ / 112 = 10 ^−5.05 mol / liter, and the pH is 5.05, even when considered under the most severe conditions for dilution, the general drainage passage The pH of the water discharged into the water never falls below 5.
[0023]
That is, acidic drain can be safely discharged without exceeding the local government standard range (generally pH is 5 to 9).
Moreover, since there is no need to provide a neutralizing device, the instrument does not increase in size, and the structure of the diluting device is simple, so that the manufacturing cost can be kept low.
Furthermore, it is not necessary to draw water from the water supply for dilution, and the water charge is not increased.
[0024]
In the example described above, the pH of the drainage was calculated in the case where the amount of acid drain generated was maximized in consideration of the worst condition, but the thermal efficiency was generally 90 to 95% even with a high efficiency water heater. It is. Next, the pH of the wastewater in the actual use state is calculated.
For example, in a highly efficient water heater with a thermal efficiency of 95%, if the true calorific value relative to the total calorific value is 90.3%, 2.3% is lost, and the true calorific value is 88%. The latent heat is 7% (= 95-88).
Therefore, when the input is 30,000 kcal / hour, the latent heat is calculated as 2,100 kcal / Nm ³ and the drain amount is 3.52 liters / hour (= 2,100 ÷ 597.1).
[0025]
Since the thermal efficiency is 95%, the output is 28,500 kcal / hour (= 30,000 × 0.95) with respect to the input of 30,000 kcal / hour. Is 518 liters / hour (= 28,500 kcal / hour ÷ 55 cal / g).
Therefore, the amount of water that can be used for dilution of acidic drain is 148 times (= 545 / 4.88) the amount of acidic drain.
[0026]
Accordingly, the hydrogen ion concentration of the acid drain after dilution is 10 ⁻³ / 148 = 10 ^−5.17 mol / liter, the pH is 5.17, and the acidity is further higher than 5.05 when the thermal efficiency is 100%. Low.
Moreover, in a water heater with a thermal efficiency of 95%, when the water flow is raised by 10 ° C., the amount of water used is 2,850 liters / hour, which is 814 times the amount of acidic drain, and the pH of the waste water at that time is 5 .91, approaching neutrality and safe.
Moreover, in the water heater with low thermal efficiency, the pH of the waste water is further increased, which is safer.
[0027]
"The first embodiment"
Next, a first embodiment of the present invention will be described with reference to FIG. In addition, a different part from reference embodiment is demonstrated, the same code | symbol is attached | subjected about the overlapping part, and the description is abbreviate | omitted. The water heater 11 of the first embodiment is basically different in that a drain reservoir 39, a drain valve 37, and a flow rate sensor 62 are provided in the water heater 10 of the reference embodiment.
[0028]
In the water heater 10 of the reference embodiment, when hot water is stored in the wash basin 63, the sink 64, and a bathtub (not shown) during hot water supply where drain is generated, the hot water drainage is discharged to the drain pipe 65 and the drain is discharged. However, it is not always possible to dilute the drain by shifting the timing.
Therefore, in the water heater 11 of the first embodiment, the drain is reliably diluted with the hot water drainage by matching the timing of discharging the drain with the timing of discharging the hot water drainage.
[0029]
The water heater 11 of the present embodiment includes a drain reservoir 39 made of vinyl chloride that is provided upstream in the drain passage 35 and stores drain, a drain valve 37 that is provided downstream and opens and closes the drain passage 35 so that the opening degree can be adjusted, and drainage. And a flow sensor 62 provided upstream of the drain passage 35 in the pipe 65.
[0030]
In the water heater 11 having such a configuration, the acidic drain generated in the heat exchanger 18 during hot water supply is accumulated in the drain reservoir 39 upstream of the drain valve 37 closed through the drain passage 35. The opening degree of the drain valve 37 is set by the burner controller 58 so as to increase as the flow rate of hot water / drainage from the sink 64, the wash basin 63 and the bathtub detected by the flow sensor 62 increases.
When the flow sensor 62 detects that the hot water drainage is flowing at a predetermined flow rate, the drain valve 37 is opened at an opening degree corresponding to the hot water drainage flow rate, and the acidic drain in the drain reservoir 39 is drained in the drain passage 35. It flows through the valve 37 to the drain pipe 65, mixes with the hot water drainage from the sink 64 and the bathtub, is diluted to a safe pH level, and then discharged to the sewer 66.
In this way, the drain discharge flow rate is set according to the hot water drainage flow rate, and drainage is performed. Therefore, even when hot water is not drained at the same time as hot water is added to the bathtub, the drain can be reliably diluted with hot water drainage. it can.
[0031]
As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, it can implement in a various aspect in the range which does not deviate from the meaning of this invention.
For example, the heat exchanger 18 may be disposed above the burner 22, and a drain receiver may be provided between them to connect to the drain passage 35.
[0032]
Further, the water heater 11 of the first embodiment, the material of de Len reservoir 39 and drain passage 35, but not limited to vinyl chloride, may be any acid-resistant material.
[0033]
【The invention's effect】
As described above in detail, according to the hot water supply device of the first aspect of the present invention, the drain passage is connected to the drain pipe, and the drain is diluted with the hot water drainage generated simultaneously with the drain. It is possible to reduce the acidity of the discharged wastewater to a safe level at a low cost.
[0034]
Further, only when Tokoro constant flow over hot water drainage is detected, for discharging by mixing drained hot water drainage to the public drainage passage, when used in reservoir hot water supply water also reliably drain Can be diluted.
[Brief description of the drawings]
FIG. 1 is a schematic view of a forced combustion water heater according to a reference embodiment.
FIG. 2 is a schematic view of the forced combustion water heater according to the first embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 18 ... Heat exchanger, 18a ... Heat exchanger tube, 18b ... Fin, 20 ... Combustion chamber, 22 ... Burner, 32 ... Exhaust hood, 35 ... Drain passage, 37 ... Drain valve, 39 ... Drain reservoir, 60 ... Hot water supply pipe, 61 ... Hot water tap, 62 ... Flow sensor, 65 ... Drain pipe, 66 ... Sewer.

Claims (1)

In a water heater provided with a heat exchanger that heats water through the combustion heat of the burner and collects latent heat in the combustion exhaust, and a drain passage that discharges the drain generated in the heat exchanger to the outside of the body,
The drain passage is connected to a drain pipe outside the water heater that discharges hot water waste water after the hot water from the heat exchanger is used to the general drain passage ,
A flow rate sensor for detecting the flow rate of hot water drainage is provided at a position upstream from the connection portion of the drainage pipe with the drain passage,
In the drain passage, in order from the upstream, a drain reservoir for storing drain, and an on-off valve for opening and closing the drain passage,
When the flow rate sensor detects a hot water supply / drainage flow rate of a predetermined amount or more, the open / close valve is opened at an opening corresponding to the detected hot water supply / drainage flow rate, and the drain accumulated in the drain reservoir is mixed with the hot water supply wastewater. A water heater characterized by being discharged into a drainage passage .

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