JPWO2011114452A1 - Scale deposition method, water heater and scale deposition apparatus - Google Patents

Abstract

The controller 31 closes the valves 7 and 9, opens the valves 4 and 12, and introduces the water to be treated into the vacuum deaeration tank 1 with the introduction pump 3. Next, when the water level in the vacuum deaeration tank 1 reaches a predetermined position, the controller 31 stops the introduction pump 3 and closes the valves 4 and 12. Next, the controller 31 opens the valve 9 and performs “vacuum deaeration” of the water to be treated by the vacuum pump 10. Next, the controller 31 stops the vacuum pump 10, closes the valve 9, opens the valve 12, and sets the vacuum deaeration tank 1 to “open atmospheric pressure”. Next, the controller 31 closes the valve 12 and opens the valve 9, operates the vacuum pump 10, and performs vacuum deaeration of the water to be treated again. Thereafter, the controller 31 alternately repeats “opening atmospheric pressure” and “vacuum degassing” a predetermined number of times, and finally performs vacuum degassing to finish the process.

Description

  The present invention relates to a method for promoting insolubilization of hardness components in water, a water heater using the method, and an apparatus for implementing the method.

  There are electric water heaters and gas water heaters that supply hot water to bathrooms and kitchens, all of which have heat exchangers for transferring heat to water. In heat exchangers, it is important to keep the heat transfer surface clean to transfer heat to the water. When the wall surface of the heat exchanger becomes dirty, the heat transfer area is reduced and the heat conduction is deteriorated, resulting in a decrease in heat transfer performance. Further, accumulation of dirt may lead to blockage of the flow path.

  In areas with high hardness components (also called calcium ions, magnesium ions, or scale components) in water, carbonate crystals such as calcium and magnesium, called scales, adhere to the inside of the heat exchanger due to heating, resulting in reduced heat transfer performance. Trouble occurs. The hardness component exists in an ionic state in water. The mechanism by which the hardness component in the ionic state adheres as a scale has not been fully elucidated. However, as one of the mechanisms, molecules such as calcium carbonate precipitate on the surface of the high-temperature part such as the wall surface of the heat exchanger, and the growth of the scale proceeds with the molecule formed on the surface of the high-temperature part as the nucleus. It is done. In this way, the precipitation of molecules such as calcium carbonate on the surface of the high temperature portion becomes the starting point of scale adhesion. For this reason, if molecules such as calcium carbonate are preliminarily precipitated in water before the water containing the scale component is heated to a high temperature, the chance of the molecules precipitating on the surface of the high temperature part when the temperature is raised can be reduced. . As a result, it is considered that scale adhesion on the surface of the high temperature part can be prevented.

Calcium carbonate, which is the main factor of scale, changes its precipitation amount in water based on the equilibrium of the following equation (1).
CaCO ₃ ↓ + CO ₂ + H ₂ O⇔Ca (HCO ₃ ) ₂ (1)
Here, if CO ₂ (carbon dioxide present in water and called free carbonic acid) is removed from the water, the equilibrium proceeds to the left in equation (1), and precipitation of calcium carbonate molecules proceeds. Therefore, how to remove free carbonic acid is important to promote precipitation of calcium carbonate molecules in water. Therefore, an efficient free carbonic acid removal method is required.

  Immediately after the molecules are precipitated in water, the individual molecules are dispersed. In order to further promote precipitation, it is very effective to have what should be called “crystal nuclei” for concentrating dispersed molecules and promoting crystallization.

  As a technique for removing free carbonic acid, there is Patent Document 1, for example. In Patent Document 1, after adding a flocculant and an alkali to water so that the pH is 10 or more, the water is pumped into an aspirator type gas-liquid mixing means 210 as shown in FIG. Run water through 113. As a result, the pressure is reduced in the vicinity of the air inlet 114 and air is sucked from the air inlet 114. And it is disclosed that the hardness component in water is insolubilized by mixing water and air, and the precipitated calcium salt and magnesium salt are adhered to the flocculant and removed.

JP-A-5-92198

  In patent document 1, in order to make it easy to remove free carbonic acid, water used as an object is made alkaline beforehand. Increasing the pH in this way is effective for removing free carbonic acid, but an injection facility for the alkali before treatment and the acid after treatment (necessary for adjusting the pH of water) is indispensable. For this reason, cost becomes high. In addition, it is extremely difficult to inject such an alkali or acid into hot water that is directly touched by a person. Moreover, as a method for removing free carbonic acid, air is mixed under reduced pressure, and free carbonic acid is removed by air exposure. However, the calcium salt and the magnesium salt precipitated by removing the free carbonic acid are aggregated using a flocculant to promote the precipitation. This flocculant also requires an injection mechanism, and it is not realistic to add a chemical such as the flocculant to hot water that is directly touched by a person.

  Therefore, in Patent Document 1, although the effects of removing free carbonic acid and promoting precipitation are obtained, it is necessary to add chemicals to each of them, which increases costs and is difficult to apply to hot water that is directly touched by humans. was there.

  The present invention eliminates the need for chemicals such as alkalis, acids, and flocculants, realizes the removal of free carbonic acid, promotes precipitation of calcium salts and magnesium salts, is low in cost, and does not adversely affect the human body. The purpose is to provide a scale deposition apparatus.

The scale deposition method of the present invention is:
In a scale deposition method for depositing scale in a liquid containing a scale component,
A reduced pressure state with respect to the liquid to be subjected to scale deposition and a pressurized state that is higher than the liquid pressure in the reduced pressure state are repeatedly generated over time, and the repeated reduced pressure state and the pressurized state are repeated. A hydraulic pressure changing step for depositing scale in the liquid is provided.

  According to the present invention, fine bubbles that become the core of scale deposition can be formed by an operation in which the liquid pressure is once changed from a low state to a high state and then the liquid pressure is decreased again. Therefore, according to the present invention, it is possible to promote precipitation of scale such as calcium carbonate in a liquid without adding an alkali or a chemical such as a flocculant. Therefore, if this invention is used, in the system which handles the water (liquid) which people touch directly, such as a water heater, scale adhesion to a heat exchanger, piping inside, etc. can be prevented and suppressed. Therefore, according to this invention, the fall of the heat transfer performance of a heat exchanger can be prevented, and the whole hot water supply system can be maintained in a favorable state.

FIG. 4 shows degassing conditions for treatment 1 and treatment 2 in the first embodiment. The characteristic view which shows the relationship between processing time and the free carbonic acid residual ratio in Embodiment 1. FIG. FIG. 3 is a characteristic diagram showing the relationship between the processing time and the calcium carbonate precipitation rate in the first embodiment. The characteristic view which shows the relationship between the ratio r of vacuum deaeration time, the free carbonic acid residual rate, and the calcium carbonate precipitation rate in Embodiment 2. FIG. FIG. 4 is a configuration diagram of a scale deposition apparatus 110 in the third embodiment. The figure which shows the state of each pump and each valve controlled by the controller 31 in Embodiment 3. FIG. FIG. 5 is a configuration diagram of a scale deposition apparatus 120 in a fourth embodiment. FIG. 6 is a configuration diagram of a scale deposition apparatus 130 in a fifth embodiment. The block diagram of the scale depositing apparatus 140 in Embodiment 6. FIG. The figure which shows the state of each pump and each valve controlled by the controller 31 in Embodiment 6. FIG. The block diagram of the scale depositing apparatus 150 in Embodiment 7. FIG. The figure which shows the state of each pump controlled by the controller 31 in Embodiment 7. FIG. The block diagram of the scale deposition apparatus 160 in Embodiment 8. FIG. The block diagram of the aspirator type gas-liquid mixing means of a prior art.

Embodiment 1 FIG.
With reference to FIGS. 1 to 3, the scale deposition method of the first embodiment will be described. The first embodiment describes an experiment related to a scale deposition method. The scale deposition method of the first embodiment includes a reduced pressure state (depressurization by degassing) with respect to a liquid (for example, water) to be subjected to scale deposition, and a pressurized state (high pressure) that is higher than the liquid pressure in the reduced pressure state. Pressure increase due to release of atmospheric pressure) is repeatedly generated as time elapses, and a hydraulic pressure changing step is performed in which scale is deposited in the liquid by repeating the reduced pressure state and the pressurized state. Hereinafter, the experimental method and experimental results of Embodiment 1 will be described. As a scale which precipitates, it is calcium carbonate, for example.

(experimental method)
"Hardness 300mg / L, pH 7.8, volume 1.0L"
Against water
(Process 1) Vacuum degassing 1 (continuous degassing),
(Process 2) Vacuum degassing 2 (intermittent degassing),
(Process 3) "Aspirator + air introduction",
Each process of was performed.

(Process 1, Process 2)
In vacuum degassing 1 (continuous degassing) and vacuum degassing 2 (intermittent degassing), 1.0 L of sample water is put into a 1.5 L vacuum vessel, and the pressure during vacuum degassing of the gas phase is 0. The pressure was set to 0.02 MPa (150 Torr).

(Deaeration conditions)
FIG. 1 is a diagram showing the degassing conditions of processing 1 and processing 2. FIG. FIG. 1A shows vacuum degassing 1 (continuous degassing), and FIG. 1B shows vacuum degassing 2 (intermittent degassing). In vacuum degassing 1 (continuous degassing), the pressure during vacuum degassing is maintained at 0.02 MPa from the state of atmospheric pressure (0.1 MPa). In vacuum degassing 2 (intermittent degassing), the operation of “stop vacuum degassing for 8 minutes after performing vacuum degassing for 2 minutes” was repeated. When the vacuum degassing was stopped, air was introduced into the gas phase to return the pressure to atmospheric pressure (0.1 MPa). That is, “r” in FIG. 1B corresponds to 2 minutes, and the period of “1-r” corresponds to 8 minutes. As shown in FIG. 1B, the decompression state (deaeration period r) and the pressurization state (atmospheric pressure release period “1-r”) are defined as one cycle, and the decompression state and the pressurization state are periodically changed. generate.

(Process 3)
Process 3 “Aspirator + Air Introduction” is a prior art reproduction test. In this treatment 3, sodium hydroxide was added as an alkali to 1.0 L of sample water poured into a 1.5 L container to adjust the pH to 10. And aluminum sulfate was added as a flocculant so that it might become 1 mg / L. The sample was drawn from the container with a pump, passed through an aspirator-type gas-liquid mixer, and then a circulation line was provided to return to the container, and the pump was operated to perform the processing.

(Free carbonic acid residual rate)
FIG. 2 is a diagram showing the relationship between the treatment time and the free carbonic acid residual ratio (residual concentration / initial concentration) in the present experiment with respect to treatment 1 to treatment 3. As shown in FIG. 2, in “Aspirator + air introduction” of the treatment 3, the free carbonic acid residual ratio rapidly decreased immediately after the operation, and thereafter the speed gradually decreased. On the other hand, in vacuum degassing, both the vacuum degassing 1 (continuous degassing) and the vacuum degassing 2 (intermittent degassing) showed the same decrease in the free carbonic acid residual rate at the initial stage of the treatment. In the continuous degassing of vacuum degassing 1, the remaining rate was remarkably reduced.
On the other hand, in the intermittent degassing of the vacuum degassing 2, the rate of decrease of free carbonic acid was maintained, and the treatment time for which the free carbonic acid concentration became almost zero was not significantly different from “Aspirator + Air introduction” of the treatment 3.

(Calcium carbonate precipitation rate)
FIG. 3 is a diagram showing the relationship between the treatment time and the calcium carbonate precipitation rate (the precipitated calcium carbonate concentration / the maximum calcium carbonate concentration that can be precipitated from the initial calcium ion concentration) in this experiment with respect to treatment 1 to treatment 3. It is. As shown in FIG. 3, in the treatment 3 “Aspirator + Air introduction”, the precipitation rate of calcium carbonate increased immediately after the operation, but became constant at about 50%. This is mainly due to the amount of the flocculant added, and shows that there was a precipitation limit of about 50% in the amount added in this experiment.
In vacuum degassing, the tendency is greatly different between vacuum degassing 1 (continuous degassing) and vacuum degassing 2 (intermittent degassing). In the continuous degassing of the vacuum degassing 1, the increase in the precipitation rate was small, whereas in the intermittent degassing of the vacuum degassing 2, the precipitation rate increased remarkably and the deposition rate reached about 95%.

From this experimental result, the intermittent deaeration of vacuum deaeration 2 is almost inferior to the removal of free carbonic acid, although the removal of free carbonic acid is slightly inferior to the “aspirator + air introduction” of treatment 3 at the beginning of the treatment. It was found that the time required for this was equivalent.
Moreover, the intermittent deaeration of vacuum deaeration 2 causes the calcium carbonate precipitation rate to deposit nearly 100% of calcium carbonate without being restricted by the amount of aggregating agent as seen in “Aspirator + air introduction”. It became clear that it was possible.
From this, intermittent degassing of vacuum degassing 2 has the same or better effect than "aspirator + air introduction" without adding sodium hydroxide and aluminum sulfate added by "aspirator + air introduction" There was found. Therefore, it was found that the intermittent degassing of the vacuum degassing 2 is an extremely effective method for removing free carbonic acid and precipitating calcium carbonate.

  In the intermittent deaeration in FIG. 1B, 1.0 L of water to be treated was put in a volume of 1.5 L. And the atmosphere of the volume 0.5L which exists in the space of difference (volume 0.5L) was deaerated, and atmospheric pressure open | released. In the deaeration period (ratio of ratio r), the pressure was 0.02 MPa (150 Torr), but the pressure in the deaeration period was less than 0.067 MPa (500 Torr), and the pressure in the period corresponding to “1-r” was 0.067 MPa or more. The atmospheric pressure (0.1 MPa) or less may be used. For example, the pressure during the deaeration period may be a value less than 0.067 MPa and in the vicinity of 0.067 MPa, and the pressure during the period corresponding to “1-r” may be atmospheric pressure.

  As described above, the operation shown in FIG. 1B, in which the water pressure is once changed from a low state to a high state, and then the water pressure is reduced again, without adding an alkali or a chemical agent such as a flocculant. Precipitation of scales such as calcium into the liquid can be promoted.

Embodiment 2. FIG.
With reference to FIG. 4, the scale deposition method (hydraulic pressure changing step) of the second embodiment will be described. In the scale deposition method of the second embodiment, when one cycle is “1” in FIG. 1B, the “ratio r” that is the ratio of the period of reduced pressure is 0.1 ≦ r ≦ 0.3. Explaining that the range is preferable for scale deposition.

(experimental method)
In the second embodiment,
"Hardness 300mg / L, pH 7.8, volume 1.0L"
Continuous deaeration (treatment 1) and intermittent deaeration (treatment 2) were performed for 24 hours. The gas phase pressure during degassing was 0.02 MPa (150 Torr). As shown in FIG. 1 (b), intermittent deaeration was repeated by performing vacuum deaeration and then stopping the vacuum deaeration and introducing air into the vacuum gas phase to return the pressure to atmospheric pressure.

(Conditions for intermittent deaeration: ratio r)
The condition for intermittent deaeration is that the sum of the intermittent deaeration time and the atmospheric pressure release time is 10 minutes (corresponding to “1” in FIG. 1B), and the ratio of the vacuum deaeration time in this 10 minutes (see FIG. 1 (b) corresponding to “r”). That is, when the intermittent deaeration time is 30 seconds (atmospheric pressure release time 9 minutes 30 seconds), the vacuum deaeration time ratio r (also referred to as time ratio r) is 0.05. In the case of intermittent degassing time of 2 minutes (atmospheric pressure release time of 8 minutes), the ratio r of vacuum degassing time is 0.2. In the case of intermittent degassing time 10 minutes (atmospheric pressure release time 0 minutes), that is, continuous degassing, the ratio r of vacuum degassing time is 1.0.

(Ratio r and calcium carbonate precipitation rate)
FIG. 4 is a graph showing the relationship between the ratio r of the vacuum degassing time, the free carbonic acid remaining rate, and the calcium carbonate precipitation rate in this experiment. As shown in FIG. 4, the free carbonic acid residual ratio is 20% or less when the ratio r is 0.2 or more. On the other hand, the deposition rate of calcium carbonate tended to decrease when the ratio r was 0.1 or more after the ratio r exceeded 80% at 0.1 and reached a maximum at 0.2.

As a result, when the vacuum degassing time is too short, the removal of free carbonic acid does not proceed.On the other hand, when the vacuum degassing time is too long, the gas components in the air are not sufficiently dissolved, and precipitation occurs during re-vacuum degassing. This indicates that the generation of microbubbles as nuclei has not progressed. On the other hand, when the time ratio r is 0.1 to 0.3, the removal of free carbonic acid and the dissolution of the gas component are appropriately balanced, and as a result, a high calcium carbonate precipitation rate of 80% or more can be secured. It is thought that it was made. From the experimental results shown in FIG. 4, as the processing conditions for intermittent deaeration, the time ratio r of the vacuum deaeration time to the sum of the intermittent deaeration time and the atmospheric pressure release time (when the sum is 1),
“0.1 ≦ r ≦ 0.3”
Is effective.

  As described above, scale precipitation can be more effectively promoted by setting the time ratio r in the range of 0.1 to 0.3.

Embodiment 3 FIG.
In the following third to eighth embodiments, a scale deposition apparatus that performs the scale deposition method described in the second embodiment will be described. The scale deposition method including the liquid pressurization step is realized by the hydraulic pressure variable mechanism 32, the controller 31, and the like described below.

  FIG. 5 is a schematic configuration diagram of the scale deposition apparatus 110 according to the third embodiment. The scale deposition apparatus 110 will be described with reference to FIG. The scale deposition apparatus 110 includes a controller 31 (control unit), a hydraulic pressure variable mechanism 32, a supply mechanism 33, a vacuum deaeration tank 1, and the like. The controller 31 controls each pump and each valve. The controller 31 and each pump and each valve are connected by a signal line 311. Note that the signal line 311 is omitted in the scale deposition apparatuses 120 to 160 after the fourth embodiment. The hydraulic pressure variable mechanism 32 includes a vacuum pump 10, a valve 9, and a valve 12. The hydraulic pressure variable mechanism 32 is controlled by the controller 31 to change the hydraulic pressure of water (an example of a liquid) that is an object of scale deposition. The supply mechanism 33 includes a discharge pump 6 and a valve 7. The supply mechanism 33 executes a supply step of supplying water after the scale precipitation treatment to another device. The vacuum deaeration tank 1 contains water to be treated and air (an example of gas) that forms an interface between the water to be treated.

(Configuration of scale deposition apparatus 110)
As shown in FIG. 5, to-be-treated water introduction pipe 2, treated water outlet pipe 5, vacuum pipe 8, and air introduction pipe 11 are connected to vacuum deaeration tank 1. In addition, an introduction pump 3 and a valve 4 are connected to the treated water introduction pipe 2. A discharge pump 6 and a valve 7 are connected to the treated water discharge pipe 5. A vacuum pump 10 and a valve 9 are connected to the vacuum pipe 8. A valve 12 is connected to the air introduction pipe 11.

(Operation)
FIG. 6 shows the state of each pump and each valve controlled by the controller 31. The “circle” in FIG. 6 indicates that the pump is operating or the valve is open. “P3” indicates the introduction pump 3, and V4 indicates the valve 4. The operation of the scale deposition apparatus 110 will be described with reference to FIG.

(Step 1)
In step 1, the controller 31 closes the valves 7 and 9 and opens the valves 4 and 12. In this state, to-be-treated water that is subject to scale deposition, such as tap water, is sent from the to-be-treated water introduction pipe 2 to the vacuum deaeration tank 1 by using the introduction pump 3.
(Step 2)
In step 2, when the water level in the vacuum deaeration tank 1 reaches a predetermined position, the controller 31 stops the introduction pump 3 and closes the valves 4 and 12.
(Step 3)
In step 3, the controller 31 opens the valve 9 and operates the vacuum pump 10 to perform vacuum deaeration of the water to be treated.
(Step 4)
In Step 4, after a predetermined time has elapsed, the controller 31 stops the vacuum pump 10, closes the valve 9, opens the valve 12, and opens the vacuum deaeration tank 1 to atmospheric pressure.
(Step 5)
In Step 5, after a predetermined time has elapsed, the controller 31 closes the valve 12, opens the valve 9, operates the vacuum pump 10, and again performs vacuum deaeration of the water to be treated.

(Step 6: Repeat processing)
In step 6, the controller 31 repeats “atmospheric pressure release, vacuum deaeration” (step 4, step 5) a predetermined number of times, and finally performs vacuum deaeration (step 5) and ends. “Atmospheric pressure release, vacuum deaeration” (steps 4 and 5) repeatedly executed by the controller 31 is the same as that described in the first and second embodiments. That is, the controller 31 performs intermittent deaeration by repeating Step 4 and Step 5 as shown in FIG. In this case, as described in the second embodiment, the time ratio r is in the range of 0.1 to 0.3.
This will be described more specifically. In the vacuum deaeration of step 3 and step 5, the hydraulic pressure variable mechanism 32 receives the control from the controller 31 and reduces the pressure of the space 41 where the air exists by sucking the atmosphere of the vacuum deaeration tank 1. In step 4, when the atmospheric pressure is released, the hydraulic pressure variable mechanism 32 is controlled by the controller 31 to increase the pressure in the space 41 by supplying air from the air introduction pipe 11 to the space 41. The controller 31 generates a depressurized state (vacuum deaeration) and a pressurized state (atmospheric pressure release) of the water to be treated by pressure reduction control and pressure increase control in the space 41 with respect to the fluid pressure variable mechanism 32. The controller 31 periodically increases or decreases the water pressure of the water to be treated by increasing or decreasing the air pressure in the space 41 above the water to be treated under the control of the fluid pressure variable mechanism 32.

(Step 7)
In Step 7, the controller 31 then closes the valve 9, stops the vacuum pump 10, opens the valves 12 and 7, operates the outlet pump 6, and guides the treated water through the treated water outlet pipe 5, Supply to water heaters.

  In this way, vacuum deaeration is performed, and then the water pressure is once increased to atmospheric pressure. Thereafter, vacuum deaeration is performed again, and this is repeated to remove free carbonic acid contained in the water. At the same time, since fine bubbles are formed again when vacuum degassing is performed, the fine bubbles can be used as nuclei for scale deposition of calcium carbonate or the like, so that precipitation of scale in water can be promoted.

Embodiment 4 FIG.
FIG. 7 is a configuration diagram of the scale deposition apparatus 120 according to the fourth embodiment. The scale precipitating device 120 puts the air introduction pipe 11 into the water to be treated with respect to the scale precipitating device 110 of the third embodiment, and further installs the air diffusion pipe 13 at the end of the air introduction pipe 11 on the water to be treated. This is a configuration provided. Other than that, it is the same as the scale deposition apparatus 110.

  Next, the operation of the scale deposition apparatus 120 will be described with reference to FIG. Similar to the scale depositing device 110 of the third embodiment, the scale depositing device 120 introduces the water to be treated, repeats vacuum degassing and atmospheric pressure release a predetermined number of times, and then derives the treated water. Since the above operation procedure is the same as that of Embodiment 3, the description thereof is omitted.

  A feature of the scale deposition apparatus 120 is that air is introduced through the air introduction pipe 11 and the diffuser pipe 13 connected to the lower end thereof in the atmospheric pressure release process (step 4 in FIG. 6).

  The fluid pressure variable mechanism 32 can increase the air pressure in the space 41 above the water to be treated by introducing air (aeration) through the air diffuser 13 disposed in the water to be treated. The dissolution of the gas component in the air into the water to be treated can be promoted, and the amount of fine bubbles, that is, the nuclei of scale precipitation, can be increased when performing vacuum deaeration again. Therefore, precipitation of the scale in water can be further promoted.

Embodiment 5 FIG.
FIG. 8 is a configuration diagram of the scale deposition apparatus 130 according to the fifth embodiment. As shown in FIG. 8, the scale depositing device 130 has an air pump 14 connected to the air-side tip of the air introduction pipe 11 with respect to the scale depositing device 120 of the fourth embodiment. In addition, an air exhaust pipe 15 is connected to the vacuum deaeration tank 1, and a valve 16 is connected to the air exhaust pipe 15. The rest is the same as the scale deposition apparatus 120 of FIG.

  Next, the operation of the scale deposition apparatus 130 will be described with reference to FIG. Similar to the scale precipitating device 120 of the fourth embodiment, the scale precipitating device 130 introduces water to be treated, repeats vacuum degassing and atmospheric pressure release a predetermined number of times, and then derives the treated water. Since the operation procedure is the same as that of the scale deposition apparatus 120, a description thereof will be omitted.

  The scale deposition apparatus 130 opens the valve 12 and the valve 16 when air is introduced through the air introduction pipe 11 and the diffuser pipe 13 connected to the lower end of the air introduction pipe 11 in the step of releasing the atmospheric pressure (step 4 in FIG. 6). At the same time, the air pump 14 is operated to introduce air into the water to be treated from the air pump 14 through the air diffuser 13, and the introduced air is discharged from the air discharge pipe 15. When vacuum deaeration is performed after a predetermined time, the scale deposition apparatus 130 (controller 31) stops the air pump 14 and closes the valves 12 and 16, and then performs the same processing as in the third embodiment.

(Characteristics of scale deposition apparatus 130)
The feature of the scale deposition apparatus 130 is that air is introduced into the water to be treated using the air pump 14 and the air diffuser 13 when the atmospheric pressure is released.

  Thus, by forcibly introducing air using the air pump 14 and the air diffuser 13, dissolution of the gas components in the air into the water to be treated can be further promoted, and the fineness when performing vacuum deaeration again. The amount of bubbles, that is, the nuclei of scale deposition, can be further increased, and the precipitation of scale in water can be further promoted.

Embodiment 6 FIG.
FIG. 9 is a configuration diagram of the scale deposition apparatus 140 according to the sixth embodiment. First, the configuration of the scale deposition apparatus 140 will be described with reference to FIG. In the scale deposition apparatus 140, in FIG. 9, the hydraulic pressure variable mechanism 32 is constituted by each pump, each valve, and each pipe. As will be described later, the degassing and atmospheric pressure release by the hydraulic pressure variable mechanism 32 and the operation of supplying treated water from the treated water outlet pipe 5 (supply mechanism 33) to other devices are integrated. Therefore, in the scale depositing device 140, the hydraulic pressure variable mechanism 32 also serves as the supply mechanism 33.

  As shown in FIG. 9, the vacuum degassing tank 1, the open tank 19, and the vacuum degassing tank 22 are arranged in series. The vacuum deaeration tank 1 and the open tank 19 are connected by a pipe 17, and the open tank 19 and the vacuum deaeration tank 22 are connected by a pipe 20. Further, a valve 18 is connected to the pipe 17, and a valve 21 is connected to the pipe 20. The vacuum deaeration tank 1 is connected with a water to be treated introduction pipe 2 and a vacuum pipe 8. The treated water introduction pipe 2 is connected to an introduction pump 3 and a valve 4, and the vacuum pipe 8 is connected to a valve 9 and a vacuum pump 10. An air introduction pipe 11 and an air discharge pipe 15 are connected to the open tank 19. A diffuser pipe 13 and an air pump 14 are connected to the air introduction pipe 11. The treated water outlet pipe 5 and the vacuum pipe 23 are connected to the vacuum deaeration tank 22. A valve 7 is connected to the treated water outlet pipe 5, and a valve 24 and a vacuum pump 10 are connected to the vacuum pipe 23.

  FIG. 10 shows the state of each pump and each valve controlled by the controller 31. FIG. 10 is a view similar to FIG. Next, the operation of the scale depositing device 140 will be described with reference to FIG.

(Operation 1)
First, the operation 1 will be described. Operation 1 is a state in which the vacuum pump 10 is stopped and the valves 9 and 24 are closed as follows. This will be specifically described. As shown in FIG. 10, the controller 31 opens the valve 4, the valve 18, the valve 21, and the valve 7, closes the valve 9 and the valve 24, operates the air pump 14, operates the introduction pump 3, and tap water Then, the water to be treated is sent to the vacuum deaeration tank 1 via the water to be treated introduction pipe 2.
This operation is referred to as “operation 1”. The controller 31 guides the water in the vacuum degassing tank 1 to the open tank 19 through the pipe 17 by maintaining the state of the operation 1. Next, the water in the open tank 19 flows into the vacuum deaeration tank 22 through the pipe 20, and finally the treated water is led out from the vacuum deaeration tank 22 through the treated water lead-out pipe 5 and supplied to a hot water heater or the like. As described at the beginning of the sixth embodiment, in the scale deposition apparatus 140, the hydraulic pressure variable mechanism 32 also serves as the supply mechanism 33.

(Operation 2)
In this process, as shown in FIG. 10, the controller 31 stops the introduction pump 3, closes the valves 4, 7, 18 and 21, opens the valves 9 and 24, and operates the vacuum pump 10. . The air pump 14 is continuously operated.
This operation is referred to as “operation 2”. By the operation 2, the controller 31 performs vacuum degassing of the water in the vacuum degassing tank 1 and the vacuum degassing tank 22 in a stopped state of the water to be treated.
On the other hand, in the open tank 19, the controller 31 introduces air by the air pump 14 to dissolve the air component. After a predetermined time has elapsed, the controller 31 stops the vacuum pump 10, switches the process to operation 1, introduces new water to be treated into the vacuum degassing tank 1, and causes water in the vacuum degassing tank 22 to be led out. The controller 31 performs the operation 1 for a predetermined time to transfer the water in the vacuum degassing tank 1 to the open tank 19 and the water in the open tank 19 to the vacuum degas tank 22. Thereafter, the controller 31 stops the operation 1 and performs the operation 2, and performs vacuum degassing of the water in the vacuum degassing tank 1 and the vacuum degassing tank 22. The controller 31 repeats operations 1 and 2 to perform processing.

  In this way, in the scale deposition apparatus 140, water is sequentially fed to remove the free carbonic acid contained in the water by first performing vacuum deaeration of the water to be treated, and then introduce air while releasing the atmospheric pressure. Then, the air component is dissolved, and further, vacuum deaeration is performed again thereafter, whereby fine bubbles can be formed from the dissolved air component. Therefore, it is possible to promote the precipitation by utilizing the fine bubbles as a nucleus for precipitation of scale such as calcium carbonate.

Embodiment 7 FIG.
FIG. 11 is a configuration diagram of the scale deposition apparatus 150 according to the seventh embodiment. First, the configuration of the scale deposition apparatus 150 will be described with reference to FIG. In the scale depositing device 150, like the scale depositing device 140, the hydraulic pressure variable mechanism 32 also serves as the supply mechanism 33. In FIG. 11, the hydraulic pressure variable mechanism 32 includes each pump and each pipe.

  The configuration of the scale deposition apparatus 150 will be described with reference to FIG. A feature of the configuration of the scale deposition apparatus 150 is that it does not have a valve.

  As shown in FIG. 11, in the scale deposition apparatus 150, the vacuum degassing tank 1, the open tank 19, and the vacuum degassing tank 22 are arranged in series. The vacuum deaeration tank 1 and the open tank 19 are connected by a pipe 17, and the open tank 19 and the vacuum deaeration tank 22 are connected by a pipe 20. A liquid feed pump 25 is connected to the pipe 17, and a liquid feed pump 26 is connected to the pipe 20. The vacuum deaeration tank 1 is connected with a treated water introduction pipe 2 and a vacuum pipe 8. An introduction pump 3 is connected to the treated water introduction pipe 2, and a vacuum pump 10 is connected to the vacuum pipe 8. An air introduction pipe 11 and an air discharge pipe 15 are connected to the open tank 19. An air pump 14 is connected to the air introduction pipe 11. The treated water outlet pipe 5 and the vacuum pipe 23 are connected to the vacuum deaeration tank 22. A discharge pump 6 is connected to the treated water discharge pipe 5, and a vacuum pump 10 is connected to the vacuum pipe 23.

  FIG. 12 shows the operating state of each pump controlled by the controller 31. FIG. 12 is a view similar to FIG. Next, the operation of the scale deposition apparatus 150 will be described with reference to FIG.

(Step 1: Introduction of treated water)
As shown in FIG. 12, the controller 31 operates the introduction pump 3, the liquid feed pump 25, the liquid feed pump 26, and the lead-out pump 6, and evacuates treated water such as tap water through the treated water introduction pipe 2. It is sent to the deaeration tank 1, and the treated water is led out from the treated water lead-out pipe through the open tank 19 and the vacuum deaeration tank 22, and supplied to other devices such as a water heater.

(Step 2: Continuous operation)
In this process, the controller 31 operates the vacuum pump 10 to degas the water flowing through the vacuum degassing tank 1 and the vacuum degassing tank 22, and operates the air pump 14 to introduce air into the water flowing through the open tank 19. To dissolve the air component. Step 2 is a process of performing vacuum deaeration. The controller 31 operates all the pumps in step 2.

  As described above, in the scale deposition apparatus 150, by sequentially feeding water, first, vacuum deaeration of water to be treated is performed to remove free carbonic acid contained in the water, and then air is introduced while releasing the atmospheric pressure. Then, the air component is dissolved, and further, vacuum deaeration is performed again thereafter, whereby fine bubbles can be formed from the dissolved air component. Therefore, precipitation can be promoted by utilizing fine bubbles as a nucleus for precipitation of scale such as calcium carbonate.

Embodiment 8 FIG.
FIG. 13 is a configuration diagram of the scale deposition apparatus 160 according to the eighth embodiment. First, the configuration of the scale deposition apparatus 160 will be described with reference to FIG. The scale depositing device 160 has a configuration in which two scale depositing devices 140 of the sixth embodiment are connected in parallel to “path A” and “path B”.

  In each of the scale deposition apparatuses 110 to 140 according to Embodiments 3 to 6, the “liquid feeding process” in which the introduction pump 3 is operated to introduce the treated water and the treated water is derived, and the introduction pump 3 is stopped. There is a “degassing step” in which water is vacuum degassed and atmospheric components are released by atmospheric pressure release or air introduction. Therefore, as shown in Embodiments 3 to 6, there is a period in which treated water in the deaeration process cannot be obtained in the treatment of only one path.

  For this reason, in order to be able to supply treated water continuously, it is conceivable to provide a plurality of treatment systems. FIG. 13 shows a case where two processing systems are provided. By using two systems, when one is a liquid feeding process, the other is a degassing process. Conversely, when one is a degassing process, the other is a liquid feeding process. Continuous operation is possible by operating the two systems so as to complement each other.

  The scale depositing device 160 in FIG. 13 has a configuration in which the scale depositing device 140 according to the sixth embodiment is provided in two routes, a route A and a route B.

  In FIG. 13, the controller 31 opens the valve 4, the valve 18, the valve 21, and the valve 7 in the path A and operates the introduction pump 3 with the valve 9 and the valve 24 closed to perform the liquid feeding process. In B, the valve 4, the valve 18, the valve 21, and the valve 7 are closed, and the vacuum pump 10 is operated to perform the deaeration process with the valve 9 and the valve 24 opened. After a predetermined time elapses, each process is switched, and this is repeated sequentially. In this way, it is possible to obtain treated water continuously by alternately performing the liquid feeding step and the deaeration step.

Embodiment 9 FIG.
(1) Embodiments 6 and 7 show the case where there are two vacuum degassing tanks and one open tank, but the number of vacuum degassing tanks and open tanks is not limited to this. 3 tanks, 2 open tanks, 4 vacuum degassing tanks, 3 open tanks are arranged alternately, and vacuum deaeration tanks are arranged at the beginning and end. You may comprise.
(2) In Embodiments 5, 6, and 7, the air pump is used as the means for introducing air into the open tank, but the introducing means is not limited to the air pump. In addition to the air pump, it is sufficient if the air component can be dissolved. A stirring mechanism may be provided, or a mechanism may be provided in which water is drawn from the bottom of the open tank and sprayed from the top.
(3) Further, in the third, fourth, and fifth embodiments, the case where air is introduced into the vacuum degassing tank when the atmospheric pressure is released is shown, and in the sixth and seventh embodiments, the case where air is introduced into the open tank. Indicated. However, the gas to be introduced is not limited to air, and instead of air, a gas that does not contain carbon dioxide or from which carbon dioxide has been removed may be introduced. Even when such a gas that substitutes for air is used, the same or equivalent effect can be obtained. Thus, the hydraulic pressure variable mechanism 32 may supply not only air but also gas that does not contain carbon dioxide.

  As described above, in the first to ninth embodiments, the scale deposition method and the scale deposition method have been described. These can be applied to a water heater as a water heater using a scale deposition method or a water heater provided with a scale deposition apparatus.

  DESCRIPTION OF SYMBOLS 1 Vacuum deaeration tank, 2 to-be-processed water introduction piping, 3 introduction pumps, 4 valves, 5 treated water extraction piping, 6 extraction pumps, 7 valves, 8 vacuum piping, 9 valves, 10 vacuum pumps, 11 air introduction piping, 12 Valve, 13 Air diffuser, 14 Air pump, 15 Air exhaust pipe, 16 Valve, 17 Pipe, 18 Valve, 19 Open tank, 20 Pipe, 21 Valve, 22 Vacuum deaeration tank, 23 Vacuum pipe, 24 Valve, 25 Liquid feed pump , 26 Liquid feed pump, 31 controller, 311 signal line, 32 hydraulic pressure variable mechanism, 33 supply mechanism, 41 space, 110-160 scale deposition apparatus.

Claims (12)

In a scale deposition method for depositing scale in a liquid containing a scale component,
A reduced pressure state with respect to the liquid to be subjected to scale deposition and a pressurized state that is higher than the liquid pressure in the reduced pressure state are repeatedly generated over time, and the repeated reduced pressure state and the pressurized state are repeated. A scale deposition method comprising a hydraulic pressure changing step for depositing scale in a liquid. The hydraulic pressure change step includes
3. The scale deposition method according to claim 2, wherein the reduced pressure state and the pressurized state are periodically generated with the reduced pressure state and the pressurized state as one cycle. The hydraulic pressure change step includes
The reduced pressure state and the pressurized state are periodically generated within a range of 0.1 or more and 0.3 or less when the one cycle is set to 1. 2. The scale precipitation method according to 2. The hydraulic pressure change step includes
The pressure of the gas is reduced by sucking the gas in a deaeration tank in which the liquid and the gas forming an interface between the liquid and the liquid are confined, and a predetermined gas is introduced into the space where the gas exists. The pressure increase of the space is executed by supplying the pressure, and the pressure reduction state and the pressure increase state of the liquid are generated by the execution of the pressure reduction and the pressure increase. The scale deposition method according to any one of 2 and 3. The hydraulic pressure change step includes
The predetermined gas is supplied to a space in which the gas exists through the air diffuser and the liquid by diffusing the gas from an air diffuser disposed in the liquid. Item 5. The scale deposition method according to Item 4. The deaeration tank is
As the gas, the atmosphere is confined,
The hydraulic pressure change step includes
While supplying the atmosphere as the predetermined gas, the pressure of the space in which the gas is confined by the execution of the pressure reduction and the pressure increase is 0.067 MPa or more in the pressurized state in the one cycle. 6. The scale deposition method according to claim 4, wherein the pressure is lower than atmospheric pressure, and the pressure is less than 0.067 MPa in the reduced pressure state in the one cycle. The hydraulic pressure change step includes
The scale deposition method according to claim 4 or 5, wherein a gas not containing carbon dioxide is supplied as the predetermined gas. The scale deposition method further includes:
The scale deposition method according to claim 1, further comprising a liquid supply step of supplying the liquid on which the scale is deposited by the hydraulic pressure changing step to another apparatus.   A water heater using the scale deposition method according to claim 1. In a scale deposition apparatus for depositing scale in a liquid containing scale components,
By controlling a fluid pressure variable mechanism that changes the fluid pressure of the liquid to be subjected to scale deposition, the reduced pressure state with respect to the liquid and the pressurized state in which the fluid pressure is higher than the fluid pressure in the decompressed state are adjusted over time. A scale deposition apparatus comprising a controller that repeatedly generates with progress and deposits scale in a liquid by repeating the reduced pressure state and the pressurized state. The controller is
The scale deposition according to claim 10, wherein the reduced pressure state and the pressurized state are periodically generated by controlling the hydraulic pressure varying mechanism as one cycle. apparatus. The controller is
The reduced pressure state and the pressurized state are periodically generated within a range of 0.1 or more and 0.3 or less when the one cycle is set to 1. 11. The scale depositing apparatus according to 11.

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