JP2010175185A - Latent heat recovery type water heating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a latent heat recovery type water heating system capable of rationally lowering concentration of nitrate nitrogen in drainage to a desired concentration while minimizing usage of dilution water. <P>SOLUTION: This latent heat recovery type water heating system WH includes a heat exchanger 13B capable of recovering latent heat from a heat recovery object gas, a drainage diluting section 5 capable of performing processing of adding the dilution water to the drainage so that the concentration of nitrate nitrogen in the drainage generated in accompany with the recovery of latent heat, is lowered, and a control means 2 determining data relating to the amount of drainage to be diluted at the drainage diluting section 5, and the concentration of nitrate nitrogen of the drainage as an object of dilution or data corresponding thereto, and controlling the amount of the dilution water added to the drainage on the basis of the data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a latent heat recovery type hot water apparatus such as a hot water supply apparatus that recovers latent heat from a heat recovery target gas such as a combustion gas generated by using a burner, and more specifically, with latent heat recovery. The present invention relates to a latent heat recovery type hot water apparatus configured to reduce the concentration of nitrate nitrogen contained in a generated drain.
In the present invention, “nitrate nitrogen” includes “nitrite nitrogen”.

The present applicant has previously proposed the one described in Patent Document 1 as an example of a latent heat recovery type hot water apparatus. The latent heat recovery type hot water device described in this document is capable of hot water heating by recovering sensible heat and latent heat from the combustion gas generated by the burner using a heat exchanger. The drainage path of the drain generated in this way is provided with a reforming tank for removing formaldehyde contained in the drain. When latent heat is recovered from the combustion gas, water vapor in the combustion gas is condensed to generate a drain, which often contains formaldehyde (CH ₂ O). As the reforming treatment tank, for example, one that electrolyzes formaldehyde is used. By using this reforming treatment tank, the formaldehyde concentration in the drain is lowered. If the formaldehyde concentration in the drain is lowered in this way, it becomes possible to promote the detoxification of the drain, and for example to flow into the bathtub and discard it.

  However, the prior art has still to be improved as described below.

  That is, when NOx and HC are generated when the burner is driven to burn, these components may come into contact with the drain, so that the drain may contain nitrate nitrogen in addition to the above-mentioned formaldehyde. . Therefore, in the case of further promoting the detoxification of the drain and discarding the drain by flowing into the bathtub, for example, from the viewpoint of giving the user a sense of security, the concentration of nitrate nitrogen in the drain should be as low as possible. desired. On the other hand, in the prior art, no means for dealing with such a problem is taken, and there is room for improvement in this respect.

  Conventionally, as shown in Patent Documents 2 and 3, there is a means for neutralizing the drain by diluting the acidic drain with tap water. By diluting the drain in this way, it is possible to reduce the concentration of nitrate nitrogen in the drain to some extent. However, since the means described in Patent Documents 2 and 3 merely dilute the drain for the purpose of neutralizing the drain, the nitrate nitrogen concentration in the drain can be rationalized to a desired target concentration with a small amount of tap water. It is difficult to reduce it automatically.

JP 2008-267734 A JP 2003-56916 A JP 2003-65609 A

  The present invention has been conceived under the circumstances as described above, and rationally reduces the nitrate nitrogen concentration of the drain to a desired concentration while suppressing the amount of dilution water used as much as possible. It is an object of the present invention to provide a latent heat recovery type hot water apparatus that can be used.

  In order to solve the above problems, the present invention takes the following technical means.

  A latent heat recovery type hot water apparatus provided by the present invention includes a heat exchanger capable of recovering latent heat from a heat recovery target gas, and a drain-to-drain nitrate nitrogen concentration generated by the latent heat recovery. Obtain a drain dilution section capable of adding dilution water, data on the amount of drain to be diluted in the drain dilution section, and nitrate nitrogen concentration of the drain to be diluted or data corresponding thereto. And control means for controlling the amount of dilution water added to the drain on the basis of these data.

  According to such a configuration, it becomes possible to appropriately dilute the drain by using a minimum or a minimum amount of dilution water corresponding to the amount of drain and the concentration of nitrate nitrogen. While reducing the amount, it is easy and reliable to reduce the nitrate nitrogen concentration of the drain to a desired target concentration to promote the detoxification of the drain.

  In a preferred embodiment of the present invention, a burner that generates combustion gas as the heat recovery target gas is provided, and the control means includes first data relating to a fuel combustion amount of the burner, combustion drive of the burner. The nitrate nitrogen concentration of the drain is determined based on the second data relating to the on / off switching frequency of the heat exchanger and the third data relating to the hot water temperature in any part from the inlet to the outlet of the heat exchanger. The first or third data is obtained or used as data corresponding to the nitrate nitrogen concentration of the drain.

  Since each of the first to third data is closely related to the nitrate nitrogen concentration of the drain, it is possible to accurately determine the nitrate nitrogen concentration of the drain by using the first to third data. The data obtained or obtained can be effectively used as data accurately corresponding to the nitrate nitrogen concentration in the drain.

  In a preferred embodiment of the present invention, the drain dilution unit includes a buffer tank for temporarily storing the drain, and the drain in the drain discharge path in the buffer tank or downstream from the buffer tank. The control means obtains the average nitrate nitrogen concentration of the drain stored in the buffer tank or data corresponding thereto, and stores this data and the buffer tank. Based on the data regarding the amount of drain, it is comprised so that the quantity of the water for dilution added to the said drain may be calculated | required.

  According to such a configuration, it is possible to facilitate and correct the drain dilution process. That is, when a drain is generated in a heat exchanger, the concentration of nitrate nitrogen in the drain is not always constant, and this concentration changes according to the heat exchange conditions, the amount of heat recovery target gas, the temperature, and the like. As described above, it is difficult to accurately grasp the nitrate nitrogen concentration of the drain existing in each part of the flow channel only by causing the drain generated while the nitrate nitrogen concentration is changed to flow along the fixed flow channel. . On the other hand, according to the configuration, when the drain is stored in the buffer tank, the nitrate nitrogen concentration of the drain is averaged, and the average nitrate nitrogen concentration is obtained. Therefore, processing for accurately obtaining the value is facilitated. In addition, it becomes easy to accurately grasp the amount of drain to be diluted.

  In a preferred embodiment of the present invention, the method further comprises a reforming tank for removing formaldehyde contained in the drain to reduce the formaldehyde concentration in the drain, and the reforming tank The drain that has passed is guided to the drain dilution section and diluted with the dilution water, so that the formaldehyde concentration of the drain is further reduced.

  According to such a configuration, since the formaldehyde concentration of the drain can be reduced using the reforming treatment tank, it is more preferable to promote the detoxification of the drain. The formaldehyde concentration in the drain can be further reduced by utilizing a dilution process for reducing the nitrate nitrogen concentration. Therefore, the treatment capacity of the reforming treatment tank can be lowered by the amount of decrease in formaldehyde concentration due to dilution of the drain, which is suitable for downsizing the reforming treatment tank.

  In a preferred embodiment of the present invention, the control means obtains a dilution factor or data corresponding to the concentration required to make the nitrate nitrogen concentration of the drain below a predetermined target concentration in the drain dilution section, Obtain the dilution ratio or data corresponding to the formaldehyde concentration of the drain below the predetermined target concentration, and dilute the drain using the higher of the two data. It is configured to let you.

  According to such a configuration, both the nitrate nitrogen concentration and the formaldehyde concentration in the drain can be reduced below a desired target concentration.

  In a preferred embodiment of the present invention, the control means can set the nitrate nitrogen concentration of the dilution water or data corresponding thereto, and based on the set data, the nitrate state of the drain is set. It is configured to correct the dilution ratio or the data value corresponding to the dilution ratio required to make the nitrogen concentration equal to or lower than the predetermined target concentration.

  According to such a configuration, the following effects can be obtained. That is, for example, when tap water is used as the dilution water, nitrate water may be originally contained in the tap water itself. In addition, the nitrate nitrogen concentration of tap water varies from region to region. According to the above-mentioned configuration, it is preferable to cope with such a situation, and when the drain is diluted using dilution water containing nitrate nitrogen, and the drain is diluted using dilution water not containing nitrate nitrogen. In any case, it is possible to appropriately cope with the case, and it is possible to make the nitrate nitrogen concentration of the drain accurate to a predetermined target concentration or less while suppressing the amount of diluting water used.

  Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

It is a schematic explanatory drawing which shows an example of the latent heat recovery type hot water apparatus which concerns on this invention. It is a flowchart which shows an example of the operation | movement process procedure of the control part which the latent heat recovery type hot water apparatus shown in FIG. 1 comprises.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows an embodiment of a latent heat recovery type hot water apparatus to which the present invention is applied. The latent heat recovery type hot water apparatus WH of this embodiment includes a hot water apparatus main body 1, a control unit 2, a reforming treatment tank 3, a neutralization treatment tank 4, a drain dilution part 5 configured to include a buffer tank 50, and An exterior case 9 is provided.

  The hot water apparatus main body 1 includes a burner 11 provided in a can 10 having an exhaust port 10a in the upper part, a fan 12 for sending combustion air toward the burner 11, a primary heat exchanger 13A, and secondary heat. It has an exchanger 13B. As the burner 11, for example, a gas burner for burning a fuel gas such as natural gas is used. However, it is also possible to use an oil burner that burns fuel oil such as kerosene. When either a gas burner or an oil burner is used, the drain generated in the secondary heat exchanger 13B contains formaldehyde and nitrate nitrogen. Melting phenomenon can occur. The primary heat exchanger 13A recovers sensible heat from the combustion gas generated by the burner 11, and the secondary heat exchanger 13B recovers latent heat from the combustion gas. The drain generated along with this latent heat recovery is received by the member 14 and supplied to the reforming treatment tank 3. The hot water apparatus main body 1 is configured such that, for example, tap water is supplied to the water inlet 90, and the tap water supplied to the water inlet 90 passes through the internal water inlet 70 and the secondary heat exchangers 13 </ b> B and 1. The secondary heat exchanger 13A is sequentially passed and heated. The hot water generated by this heating is sent to the hot water outlet 91 through the internal hot water outlet 71, and the hot water can be discharged from the hot water outlet 91 toward a predetermined general hot water supply destination. A bath piping unit 75 for filling the bathtub 8 installed in the bathroom is also connected to the internal hot water supply channel 71, and hot water can be supplied to the bathtub 8 through the bath piping unit 75. It has become. The bath piping unit 75 and the other bath piping unit 76 connected to the bathtub 8 constitute a circulation path for bathing.

The reforming treatment tank 3 is for decomposing the formaldehyde contained in the drain, and the drain that has flowed down from the secondary heat exchanger 13B and received by the member 14 is modified via the piping section 15. It is guided into the quality treatment tank 3. The reforming treatment tank 3 contains a modifying material 30 mainly composed of manganese dioxide. Various materials such as powder, pellets, or honeycomb structure can be used as the modifier 30. In the reforming treatment tank 3, the drain that has flowed into the reforming treatment tank 3 from the inlet 31 flows into the outlet 32 and comes into contact with the reforming material 30 to form an oxidative decomposition reaction (CH ₂ O + O ₂ → H ₂ O + CO ₂ ) occurs, and the formaldehyde concentration in the drain decreases. Preferably, the inside of the reforming treatment tank 3 has a structure in which the flow path length is increased by causing the drain to meander up and down. In the reforming treatment tank 3, when the drain flows into the inlet 31 in a steady state where the drain is in a full state, the drain subjected to the decomposition removal treatment of formaldehyde from the outlet 32 is the drain inflow amount. The same amount as spills.

  The reforming treatment tank 3 is preferably provided with an electrothermal heater H, and the drain flowing into the reforming treatment tank 3 can be heated. The ability to decompose formaldehyde by the modifier 30 increases as the temperature of the drain increases. For this reason, for example, when the drain temperature in the reforming treatment tank 3 falls below a predetermined temperature, when the formaldehyde concentration of the drain flowing into the reforming treatment tank 3 is higher than a predetermined value, or in the reforming treatment tank 3 When the amount of drain flowing into the tank is larger than a predetermined value, the inside of the reforming treatment tank 3 is heated using the heater H. As a result, it is possible to discharge from the reforming treatment tank 3 a drain whose formaldehyde concentration is a predetermined concentration or less. The reforming treatment tank 3 is not limited to the one using the reforming material 30, and other types such as an electrolysis type as described in Patent Document 1 can also be used. .

  The neutralization treatment tank 4 has a configuration in which a neutralizing material 40 mainly composed of calcium carbonate is filled therein, and the drain that has passed through the reforming treatment tank 3 enters the neutralization treatment tank 4 from the inlet 41. Supplied. The drain is strongly acidic containing nitrogen oxides and sulfur oxides in the combustion gas, but is neutralized by flowing into the neutralization treatment tank 4 and coming into contact with the neutralizing material 40, from the outlet 42. Discharged. The neutralization treatment tank 4 is configured such that when the drain flows into the inlet 41 in a steady state where the drain is full, the neutralized drain flows out from the outlet 42 by an amount equivalent to the drain inflow amount. Yes, similar to the reforming treatment tank 3. Preferably, the neutralization treatment tank 4 is configured to have a sterilization treatment function. The sterilization function can be obtained, for example, by using a means for storing a sterilizing material (for example, tablet-like silver) in a part of the neutralization tank 4.

  The buffer tank 50 is for allowing the drain that has passed through the neutralization tank 4 to flow into the inside from the inflow port 51a and temporarily store it. In this embodiment, the buffer tank 50 is As described above, the drain dilution section 5 is configured. That is, tap water flowing through the internal water inlet 70 can be supplied to the other inlet 51b of the buffer tank 50 through the piping 55, and the drain in the buffer tank 50 can be diluted by this water supply. Is possible. The tap water used for this dilution is an example of the dilution water in the present invention, and the concentration of nitrate nitrogen in the drain can be reduced by the dilution. The piping part 55 is provided with an on-off valve V1 and a flow rate sensor 56 so that a desired amount of tap water can be introduced into the buffer tank 50 from the piping part 55 at a desired timing.

  The outflow port 52 of the buffer tank 50 is connected to the three-way valve V2 of the bath piping unit 75 through the piping unit 57, and the drain stored in the buffer tank 50 is controlled by switching the three-way valve V2. It is possible to flow into the bath piping unit 75 and flow into the bathtub 8. According to such a configuration, it becomes possible to dispose of the drain effectively using the piping section 75 for bath, and it is necessary to separately construct a dedicated pipe for disposing of the drain outside the exterior case 9. Disappears. Moreover, the time when the three-way valve V2 is switched to allow the drain to flow into the bathtub 8 can also be set to an appropriate time.

  The control unit 2 is configured using, for example, a microcomputer, and executes various data processing in addition to the operation control of each unit of the latent heat recovery hot water apparatus WH. The control unit 2 also executes processing for reducing the nitrate nitrogen concentration of the drain to a predetermined target concentration, details of which will be described later.

  Next, the operation of the above-described latent heat recovery hot water apparatus WH will be described together with an example of the operation procedure of the control unit 2 shown in the flowchart of FIG.

  First, the control part 2 calculates | requires the amount of drain generation in the secondary heat exchanger 13B, and the nitrate nitrogen density | concentration of the produced | generated drain by calculation (S1). In this process, for example, data indicating that 0.5 L of a drain having a nitrate nitrogen concentration of 30 ppm is generated and then 0.5 L of a drain having a nitrate nitrogen concentration of 10 ppm is generated. When water is passed through the secondary heat exchanger 13B and the burner 11 starts combustion driving, the amount of drain generated in the secondary heat exchanger 13B is the amount of fuel burned by the burner 11 to the secondary heat exchanger 13B. Changes in the combustion drive conditions of the burner 11 and the heat exchange conditions in the secondary heat exchanger 13B, such as the incoming water temperature, the temperature of its hot water, the temperature of the supply air from the fan 12, the exhaust temperature from the exhaust port 10a, the number of ignitions of the burner It changes corresponding to. The control unit 2 calculates a drain generation amount based on a change with time of data of a predetermined item regarding such a condition. Although not shown in the drawing, the latent heat recovery type hot water apparatus WH is provided with various sensors for acquiring the above-mentioned data, and a predetermined signal is input to the control unit 2 from these sensors. It is comprised so that.

  The concentration of nitrate nitrogen in the drain also changes in accordance with changes in the combustion drive conditions of the burner 11 and the heat exchange conditions in the secondary heat exchanger 13B. Therefore, the calculation of the nitrate nitrogen concentration by the control unit 2 is the same as the case where the drain generation amount is obtained, and the data of predetermined items relating to the combustion drive condition of the burner 11 and the heat exchange condition in the secondary heat exchanger 13B are changed over time. It is based on a change.

  However, items that greatly affect the nitrate nitrogen concentration include, for example, the temperature of water entering the heat exchanger 13B, the frequency of ON / OFF of the combustion drive of the burner 11, and the amount of fuel combustion. As for the temperature of water entering the secondary heat exchanger 13B, the higher the temperature, the smaller the amount of generated drain, but the more the combustion gas comes into contact with a small amount of the drain. Become. Regarding the on / off frequency of the combustion drive of the burner 11, the higher the frequency, the more HC and NOx are more likely to be generated, and the nitrate nitrogen concentration becomes higher. The amount of fuel combustion greatly depends on the characteristics of the burner 11, and the nitrate nitrogen concentration is likely to change as the values of these items change. Therefore, the calculation of the nitrate nitrogen concentration is performed by calculating the temperature of water entering the secondary heat exchanger 13B, or hot water in any part from the inlet to the outlet of the secondary heat exchanger 13B as data corresponding thereto. It is preferably performed based on data relating to temperature, data relating to on / off frequency of combustion drive of the burner 11, and data relating to the amount of fuel combustion. As a method for calculating the nitrate nitrogen concentration more accurately, for example, a test for operating a latent heat recovery type hot water apparatus of the same type or similar to the latent heat recovery type hot water apparatus WH under various conditions is performed. By performing in advance, the nitrate nitrogen concentration of the drain generated at that time is measured and data is collected, and this data is stored in the control unit 2 of the latent heat recovery hot water apparatus WH, and the stored data Can be used as reference data for calculating the nitrate nitrogen concentration.

  In addition to the amount of generated drain and its nitrate nitrogen concentration, the control unit 2 also executes a calculation for obtaining the formaldehyde concentration of the drain (S2). The formaldehyde concentration can be determined based on data similar to the data used when determining the nitrate nitrogen concentration, and details thereof are omitted.

  Next, when a predetermined amount (for example, 1 L) of drain is stored in the buffer tank 50, the control unit 2 obtains the average nitrate nitrogen concentration D1 of the drain at that time, and also obtains the dilution factor M1 ( S3: YES, S4, S5). The control unit 2 executes a process of grasping the flow of the drain having the nitrate nitrogen concentration obtained in step S1, and the nitrate nitrogen average concentration D1 is calculated based on the data obtained in step S1 described above. Is possible. That is, the breakdown of the drain stored in the buffer tank 50 is determined in step S1 that the drain having a nitrate nitrogen concentration of 30 ppm is 0.5 L and the drain having a nitrate nitrogen concentration of 10 ppm is 0.5 L, for example. In this case, the average concentration D1 of nitrate nitrogen in these drains is obtained as 20 ppm. The drain storage amount in the buffer tank 50 can also be obtained by calculation based on the drain generation amount. Instead, as shown by the phantom line in FIG. The drain storage amount may be detected using this. The dilution factor M1 is obtained from the values of the average nitrate nitrogen concentration D1 and the target concentration set in advance in the control unit 2. For example, when the average concentration D1 is 20 ppm and the target concentration is 10 ppm or less, the dilution factor M1 is twice.

  The control unit 2 obtains the average formaldehyde concentration D2 of the drain stored in the buffer tank 50 by calculation, and also obtains the dilution factor M2 (S6, S7). The calculation of the average formaldehyde concentration D2 can be performed based on the data obtained in step S2 described above and the formaldehyde removal rate by the reforming treatment tank 3. Since the decomposition treatment efficiency of formaldehyde in the reforming treatment tank 3 depends on the drain temperature and the drain residence time in the reforming treatment tank 3, the formaldehyde removal rate is, for example, in the reforming treatment tank 3 A value calculated based on the drain temperature and the drain residence time in the reforming treatment tank 3 can be used. However, since the drain residence time depends on the amount of drain generation (the more the drain generation amount, the shorter the drain residence time), the value of the drain generation amount can be used as an alternative value for the drain residence time. To give a specific example when calculating the average formaldehyde concentration D2, first, 0.5 L of a drain having a formaldehyde concentration of 12 ppm is generated in the secondary heat exchanger 13B. If it is 97%, the formaldehyde concentration of this drain is 0.4 ppm. Further, in the secondary heat exchanger 13B, 0.5 L of a drain having a formaldehyde concentration of 10 ppm is subsequently generated, and when the formaldehyde removal rate by the reforming treatment tank 3 for this drain is 98%, the formaldehyde concentration of this drain is Is 0.2 ppm. When these two types of drains flow into the buffer tank 50, the average formaldehyde concentration D2 thereof becomes 0.3 ppm. In such a case, when the target concentration for formaldehyde is, for example, 0.1 ppm or less, the dilution factor M2 is three times.

  After obtaining the dilution ratios M1 and M2 as described above, the control unit 2 selects a dilution ratio having a larger value out of these dilution ratios M1 and M2, and uses the selected dilution ratio as a buffer tank. The operation of diluting the drain in 50 is executed (S8, S9). This operation is started by opening the on-off valve V1 and allowing a part of tap water flowing through the internal water inlet 70 to flow into the buffer tank 50 via the piping 55. Next, the on-off valve V1 is closed when the measured value by the flow sensor 56 reaches the amount of water corresponding to a predetermined dilution rate. When the drain is diluted in this manner, both the nitrate nitrogen concentration and the formaldehyde concentration in the drain are lowered, and the detoxification of the drain is promoted. For example, when the dilution ratio M1 is 2 times and the dilution ratio M2 is 3 times, the drain in the buffer tank 50 is diluted 3 times. In this way, each of nitrate nitrogen and formaldehyde is diluted. Both of these concentrations can be reduced below their target concentrations. A series of operation control by the control unit 2 as described above is continuously repeated.

  According to the latent heat recovery hot water apparatus WH of the present embodiment, the nitrate nitrogen concentration and the formaldehyde concentration in the drain can be appropriately reduced to values below the respective target concentrations, and tap water used for dilution is used. The amount can be reduced to the minimum necessary amount to save water. When the formaldehyde concentration of the drain that has passed through the reforming treatment tank 3 has already been sufficiently lowered to the target concentration, the drain dilution unit 5 uses the dilution factor M1 only for the purpose of reducing the nitrate nitrogen concentration. It will be diluted. Therefore, in this case, the drain is diluted with the minimum amount of water necessary to reduce the nitrate nitrogen concentration to a desired target concentration or less, and water is saved appropriately.

  The above-described latent heat recovery hot water apparatus WH can be configured as follows. That is, tap water used for dilution of the drain may contain nitrate nitrogen, and its concentration differs depending on the region. As a means for coping with this, as indicated by a virtual line in FIG. 1, for example, the control unit 2 is provided with an operation switch 20 for correcting the dilution factor, and using this operation switch 20, the latent heat recovery hot water apparatus WH is provided. Is configured so that the nitrate nitrogen concentration of tap water or the approximate value thereof can be set in the area where is installed. The control unit 2 is configured to refer to the value set by the operation switch 20 when calculating the dilution ratio of the drain.

  More specifically, when the average nitrate nitrogen concentration D1 of the drain in the buffer tank 50 is 20 ppm and the target concentration of nitrate nitrogen is 10 ppm or less, the nitrate nitrogen concentration of tap water is 0 ppm by the operation switch 20. If it is set, there is the same as the case described with reference to FIG. 2, and the dilution factor M1 is set to 2 times. On the other hand, when the nitrate nitrogen concentration of tap water is set to 5 ppm, for example, the dilution factor M1 is set to 3 times. Thus, if the dilution ratio of the drain is determined in consideration of the nitrate nitrogen concentration of tap water used for dilution, it is ensured that the nitrate nitrogen concentration of the drain is lowered to a target concentration or less. Of course, in anticipation of safety, it is not necessary to estimate the concentration of nitrate nitrogen contained in tap water too much to increase the dilution factor more than necessary, so that the amount of tap water used can be reduced. The dilution factor correction data may be set by means such as writing data to the control unit 2 from the outside, for example, instead of using the operation switch 20.

  The present invention is not limited to the contents of the above-described embodiment. The specific configuration of each part of the latent heat recovery type hot water apparatus according to the present invention can be varied in design in various ways.

  In the embodiment described above, the nitrate nitrogen concentration of the drain is calculated by the control unit 2, and the drain dilution factor and the like are determined using the calculated value. However, the drain dilution factor and the like are determined. The data used in the above does not necessarily have to be the data of nitrate nitrogen concentration itself. Other data corresponding to nitrate nitrogen concentration (for example, fuel combustion amount, frequency of combustion on / off, and hot water temperature data at any part from the heat exchanger inlet to outlet) Of these, any one or a combination of two or more) may be used. The data regarding the amount of drain to be diluted may be data indicating the amount of drain in some form, and such a unit is used instead of data indicating an absolute amount using a unit such as L [liter]. Alternatively, the data may be relatively indicative of the drain amount.

  The drain dilution section referred to in the present invention is preferably configured using a buffer tank capable of temporarily storing the drain so that the dilution water can flow into the buffer tank. It is not limited. For example, dilution water can be added to the drain in the drain discharge path on the downstream side of the buffer tank. Further, the drain and the dilution water may be mixed at a desired ratio without using a buffer tank.

  It does not matter how the drain with reduced nitrate nitrogen concentration is treated. Instead of allowing the drain to flow into the bathtub, it is possible to store the drain in an appropriate place and use it for toilet water or other purposes. Alternatively, the drain may be led to a bathroom drain or the like and discarded as it is.

  As dilution water, water other than tap water can be used. As the heat recovery target gas, for example, various high-temperature gases (such as gas exhausted from a gas engine of a cogeneration system) can be used instead of the combustion gas generated by the burner. The latent heat recovery type hot water apparatus in the present invention means an apparatus having a function of recovering latent heat from a heat recovery target gas to generate hot water, for general hot water supply, bath hot water supply, heating, or snow melting. It is a concept that broadly includes various types of hot water supply devices such as, and devices that generate hot water used in addition to hot water supply.

Claims (6)

A heat exchanger capable of recovering latent heat from the heat recovery target gas,
A drain dilution section capable of adding dilution water to the drain so that the concentration of nitrate nitrogen in the drain generated with the latent heat recovery decreases; and
Obtain data on the amount of drain to be diluted in the drain dilution section and nitrate nitrogen concentration of the drain to be diluted or data corresponding thereto, and add to the drain based on these data. Control means for controlling the amount of dilution water produced;
A latent heat recovery type hot water apparatus, comprising: It comprises a burner that generates combustion gas as the heat recovery target gas,
The control means includes any one of the first data relating to the fuel combustion amount of the burner, the second data relating to the on / off switching frequency of the combustion drive of the burner, and from the inlet to the outlet of the heat exchanger. The concentration of nitrate nitrogen in the drain is determined based on the third data relating to the hot water temperature in the portion, or the first to third data are used as data corresponding to the concentration of nitrate nitrogen in the drain. The latent heat recovery type hot water device according to claim 1, wherein The drain dilution section includes a buffer tank for temporarily storing the drain, and can add dilution water to the drain in a drain discharge path in the buffer tank or downstream of the buffer tank. ,
The control means obtains the average nitrate nitrogen concentration of the drain stored in the buffer tank or data corresponding thereto, and based on this data and data relating to the amount of drain stored in the buffer tank, The latent heat recovery type hot water device according to claim 1 or 2, wherein the latent heat recovery type hot water device is configured to obtain an amount of dilution water added to the drain. It further comprises a reforming tank for reducing the formaldehyde concentration of the drain by performing a removal treatment of formaldehyde contained in the drain,
The drain that has passed through the reforming treatment tank is configured to be further reduced in formaldehyde concentration in the drain by being led to the drain dilution section and diluted with the dilution water. The latent heat recovery type hot water device according to any one of the above.   The control means obtains a dilution factor or data corresponding to the concentration of nitrate nitrogen in the drain dilution part to be equal to or lower than a predetermined target concentration, and sets the formaldehyde concentration in the drain to a predetermined target. It is configured to obtain the dilution ratio necessary for the concentration or less or data corresponding thereto, and to use the data with the higher dilution ratio of these two data to dilute the drain. Item 5. The latent heat recovery hot water device according to Item 4.   The control means can set the nitrate nitrogen concentration of the dilution water or data corresponding thereto, and based on the set data, the nitrate nitrogen concentration of the drain is made equal to or lower than a predetermined target concentration. The latent heat recovery hot water device according to any one of claims 1 to 5, wherein the latent heat recovery type hot water device is configured to correct a value of a dilution factor required for the correction or a data value corresponding to the dilution rate.

Images