JP5831894B2 - Artificial waste heat treatment system in closed water - Google Patents

Description

The present invention is an artificial exhaust heat treatment system that exhausts artificial exhaust heat generated from a building such as a house or a power plant to a closed water area.

In recent years, the so-called heat island phenomenon in which the temperature in the center of a city is higher than the temperature in the suburbs has become a problem. The heat island phenomenon is caused by various factors, one of which is the artificial population that is generated from facilities such as houses, large power plants, oil factories, and petrochemical factories due to population concentration in the city and discharged into the atmosphere. The amount of exhaust heat is increasing.

When these artificial exhaust heat is finally released into seawater as a heat release place, this has an effect on the rise in seawater temperature. In particular, in an artificial closed water area surrounded by a breakwater, it is difficult for water to be exchanged with an external water area, so seawater tends to stagnate. For this reason, the surface water temperature in the artificial closed water area in summer tends to be higher than the low water temperature.

For example, at Osaka Port, a temperature stratification peculiar to the summer season has already been formed in June, and the process of developing the stratification into a stronger one is seen through July. And this rise in the surface water temperature leads to the problem of causing a heat island phenomenon near the coast as sea breeze enters the city center.

Conventionally, onshore countermeasures such as water retention pavement and rooftop greening have been mainly taken as countermeasures against such a heat island phenomenon. (For example, see Patent Document 1 below)

However, on land heat island countermeasures, the effect is limited to a limited area in spite of huge investment, and there is a problem that a large-scale construction has to be performed in order to exert a large effect.

On the other hand, another environmental problem in a closed water area is the problem of anoxic water mass. That is, organic matter is likely to be deposited in a closed water area having poor exchange with an external water area, and an oxygen-poor state is likely to occur widely in the bottom layer. As a result, when aerobic organisms that are depleted due to lack of oxygen in the water die, the balance of environmental conditions in the water area is lost, and pests such as red tide plankton are abnormally generated.

In closed water areas (such as steep pits on the seabed or closed inner bays) that have poor interaction with external water areas, water flow is generally stagnation, and when stratification develops in the summer, surface seawater And the difference in density between the seawater in the bottom layer and the upper and lower mixing is less likely to occur. In the bottom layer, organic matter such as plankton carcasses is deposited and decomposed actively, so oxygen is consumed. As a result, an anoxic water mass with a very small amount of dissolved oxygen is formed near the bottom of the sea where the water flow is stagnant.

The hypoxic water mass formed in this way may rise near the sea surface due to strong winds and changes in tide flow, etc., in this case, causing mass death of organisms living in the sea or at the bottom of the sea, It became a factor causing the so-called blue tide.

As a method for purifying a closed water area, a method of artificially providing interchangeability with an external water area is employed. For example, in Patent Document 2 described below, means for exchanging water with an external water area through a water area entrance by civil engineering means and stirring in a closed water area are performed.

However, although it is relatively easy to stir a narrow water area such as a lake, a large-scale water flow generator is required to stir a large closed water area such as a harbor, which increases the cost. was there.
JP 2009-215853 A Japanese Patent Laid-Open No. 06-257117

The artificial waste heat treatment system of the present invention stops the acceleration of the heat island phenomenon by utilizing the low temperature bottom water outside the closed water area as cooling water for condensers for refrigerating machines, condensers for steam turbines, etc. At the same time, seawater that has risen in temperature after heat exchange is effectively used to promote vertical mixing, thereby improving the oxygen-poor water in the bottom layer in a closed water area.

The artificial waste heat treatment system to the closed water area of the present invention, water intake means for taking the bottom layer water of the bottom layer outside the artificial closed water area, heat exchange means using the bottom layer water taken by the water intake means as a heat source, Drainage means for discharging waste heat water discharged after being used in the heat exchange means to the bottom layer in the artificially closed water area.

The heat island phenomenon can be suppressed by discharging the exhaust heat from the cooling not only to the atmosphere but also into seawater having a very large heat capacity. Specifically, energy saving, cogeneration, and carbon dioxide reduction can be expected by using bottom-layered low-oxygen low-temperature water outside the closed water area surrounded by the breakwater as a refrigerant for heat exchangers and power generation. It can also be used as a refrigerant for residual waste heat water used for cooling heat exchangers and generators.

There are many studies on equipment operation patterns and seawater use methods (direct use and indirect use) when seawater, which is unused energy, is used as cooling water for heat source equipment. Not much research has been done on the topic. The present invention pays attention to temperature stratification, which is said to develop in the summer, and enhances the energy saving effect by using low temperature bottom water.

Moreover, an anaerobic state can also be improved by discharging | emitting waste-heated seawater after heat exchange to the bottom layer part in an artificial closed water area. That is, since the waste heat seawater after heat exchange has a higher temperature than the sea water in the bottom layer in the artificial closed water area, the waste heat sea water discharged to the bottom layer rises due to the density difference between the sea water and the surrounding sea water. At that time, as a result of ascending so as to attract the surrounding seawater, circulation and vertical mixing of the seawater occur in the closed water area, and the poor oxygen state can be improved.

Furthermore, a heat island phenomenon can also be suppressed by discharging | emitting waste heat seawater after heat exchange to the bottom layer part in an artificial closed water area. That is, as described above, seawater circulation and vertical mixing occur in the closed water area, and as a result, an increase in the surface water temperature can be suppressed. In central Tokyo, the sea breeze from Osaka Bay, Tokyo Bay, and other inner bays enters the city center on a typical midsummer day, so if the surface water temperature can be lowered from the current level, the sea breeze becomes cooler and stronger, and cooling and ventilation in the city center It can be expected to be promoted.

The artificial waste heat treatment system according to the present invention further comprises an oxygen mixing means for mixing a gas containing oxygen into the exhausted hot water discharged after being used in the heat exchange means, and the drain means is the oxygen mixing means. The high oxygen seawater mixed with oxygen may be discharged to the bottom layer in the closed water area. By mixing oxygen into the exhaust heat seawater to be discharged, the poor oxygen state can be further improved.

By making the drainage means a drain pipe having a plurality of discharge ports, the discharge flow velocity can be reduced and the environment in the water area can be prevented from changing significantly.

When the closed water area is a harbor surrounded by an artificial building, the drainage unit may control the amount of drainage to be discharged based on tide information. Thereby, the environmental change to a closed water area can be controlled. Here, the tide information refers to information related to tides where the sea level rises and falls due to tide force, and includes, for example, low tide / high tide time, tidal height difference, and the like.

ADVANTAGE OF THE INVENTION According to this invention, while the heat island countermeasure whose effect was geographically limited on land was implement | achieved more effectively, the poor oxygen state in a closed water area can be improved.

The figure which shows the structure of the whole system in this embodiment. Enlarged view of the drain pipe of this embodiment Sectional view and plan view of the drain pipe of this embodiment System configuration diagram used for simulation The figure which shows seawater average temperature and turbo refrigerator operating time in simulation Diagram showing simulation results

An artificial waste heat treatment system for an enclosed water area in the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of the entire system 100 in a closed water area. Closed water area means a water area with a water stagnation part where there are few opportunities for inflow and outflow of water due to geographical factors, and the water flow is likely to stagnate.If it has a water stagnation part, not only the sea but also lakes and marshes etc. included. In the present embodiment, an artificial closed water area formed by an artificial structure such as a harbor surrounded by a breakwater as shown in FIG. 1 will be described as an example, but the present invention is not limited to this.

The artificial waste heat treatment system 100 of the present embodiment has a water intake means for taking in seawater in the bottom layer outside the artificial closed water area, which is lower than the temperature of the seawater in the artificial closed water area, and the water intake means has taken in water. A heat exchanging means using seawater as a heat source; an oxygen mixing means for mixing a gas containing oxygen in the exhaust heat seawater discharged after being used in the heat exchanging means; and a high oxygen content mixed by the oxygen mixing means. And a drainage means for discharging the oxygen seawater to the bottom layer in the closed water area. Hereinafter, each means will be described in detail.

The intake means is not particularly limited as long as it draws seawater in the bottom layer outside the artificial closed water area to the sea. The technology of a deep ocean water intake facility that has been put into practical use may be used, and in this embodiment, the intake pipe 101 that sucks and takes in seawater and a pumping pump 102 that is a power source are configured.

One end of the intake pipe is a bottom layer outside the closed water area, for example, a water intake 101A extending to a depth of 10 to 20 m, and the other end is disposed in a heat exchange means (described later) installed on land. ing. By this intake pipe 101A, seawater outside the closed water area is guided to the heat exchange means. The intake pipe 101 is a flexible hose capable of disposing the intake port 101A at an arbitrary depth position.

The pumping pump 102 continuously sucks a part of the water mass forming the bottom water layer through the water pipe 101. The installation location may be on a work boat, a floating structure moored by a chain or sinker, or underwater. When operating on a work ship or a floating structure, a solar panel may be installed on the work ship or the like, and a solar cell, storage battery, or the like may be used as energy for driving a mechanical device such as a pump. When installing in water, for example, it is moored on a buoy or the like, suspended to a position of a predetermined depth, and operated with an intake port positioned at an appropriate depth.

During the period when temperature stratification is developing, the temperature of the sea water in summer varies depending on the water intake depth, but the rate is not always constant, and there is almost no difference in the water temperature beyond a certain depth. Disappear. For this reason, the deeper the depth of water intake, the better. The flexible hose is used to pump up seawater at an appropriate depth. The maximum water intake flow rate of the bottom layer water is determined by the facility cooling heat amount required by the heat exchange means described later.

In this way, the low-temperature seawater pumped from the bottom layer outside the artificial closed water area is led to the heat exchange means through the water conduit.

The heat exchanging means uses the pumped low-temperature seawater as a cooling medium for air-conditioning energy and power generation energy, and the heat exchanger 103 that has already been put into practical use can be used. The use as a cooling medium here includes use as cooling water for cooling the refrigerant.

For example, it can be used for a condenser such as an air-conditioning refrigerator installed in a district heating and cooling facility. That is, the seawater outside the gulf pumped up can be used as the cooling water for returning the refrigerant such as the chlorofluorocarbon gas evaporated by the evaporator back to the liquid refrigerant.

For example, a thermal power plant uses a condenser that cools and condenses steam exhausted from a steam turbine and condenses the steam. Boilers and steam turbines used in thermal power plants are large and the amount of steam exhausted is large, so it is possible to use seawater pumped from outside the bay to cool the exhaust steam.

Thus, by using low-temperature seawater as cooling water for a refrigerator, for example, an efficiency improvement effect for the refrigerator can be obtained, and as a result, an effect as a heat island countermeasure can be expected. It is not limited geographically like conventional onshore heat island countermeasures such as rooftop greening and water retentive pavement, and can have an effect on a wider area.

In addition, what is necessary is just to adjust the intake depth of a water intake arbitrarily in order to exhibit optimal heat exchange efficiency. Since the pumped seawater is cooler than the seawater temperature in the bay, the use efficiency can be improved.

Seawater supplied to the heat exchanger 103 is guided to oxygen mixing means. The oxygen mixing means is an oxygen supply facility 104 that mixes oxygen into the exhaust heat water from the heat exchanger 103. The means is not limited as long as the required oxygen gas can be mixed into the exhaust heat water and converted into high-concentration oxygen water. For example, compressed air may be sent and aerated by an air compressor. Further, oxygen water having a higher concentration may be generated using a liquid oxygen storage tank or an on-site oxygen generator.

As shown in FIG. 2, the exhaust heat water converted into the high-concentration oxygen water is discharged from the discharge port 105 </ b> A at the tip of the drain pipe 105 into the final bay where heat is released. 3 is an enlarged view of the distal end portion of the drain pipe, FIG. 3A is a plan view seen from the upper direction (arrow direction) in FIG. 2, and FIG. 3B is a cross-sectional view. The position of the discharge port 105 </ b> A can be moved to an arbitrary water depth, and in the present embodiment, the discharge port 105 </ b> A is located at the bottom layer in the closed water area. Further, a plurality of discharge ports 105A of the drain pipe 105 are provided, and each discharge port 105A opens upward.

The exhaust hot water used in the heat exchanger is discharged from the drain pipe 105 to the bottom layer of the closed water area. At this time, it is preferable to change the water temperature change exerted on the closed water area as gently as possible.

In this embodiment, various measures are taken so that the water temperature in the closed water area does not change significantly. That is, the water temperature change in the closed water area is determined by the difference (temperature difference), the discharge flow rate, and the discharge flow rate between the water temperature of the exhaust heat hot water and the water temperature of the artificial closed water area. In particular, the temperature difference is often restricted as an environmental impact assessment item so that water that is approximately 7 degrees or more higher than the water temperature in the water area cannot be discharged.

Therefore, in the present embodiment, the temperature of the exhaust heat water is controlled so as not to exceed 7 degrees from the bottom water temperature of the artificial closed water area and higher than the surface water temperature. Specifically, the temperature of the waste heat hot water is adjusted by the amount of drainage discharged from the drain pipe (that is, the amount of water taken from the intake pipe).

The amount of drainage from the drainage pipe 105 is determined by the amount of exhaust heat required by the heat demand facility. If the amount of exhaust heat is constant, the temperature of the exhaust heat hot water is low and the amount of exhaust flow is small if the amount of exhaust heat is large. If this is the case, the temperature of the exhaust hot water will be high.

Therefore, by adjusting the amount of water intake (that is, the amount of drainage), the temperature of the discharged water will not exceed 7 degrees below the bottom water temperature of the artificial closed water area, and will be higher than the surface water temperature of the artificial closed water area. I have control.

Moreover, in this embodiment, as shown in FIG. 3, the discharge flow velocity at the time of discharging | emitting hot waste water is controlled by changing discharge | emission cross-sectional area. Thereby, it can suppress that the environment in a closed water area changes remarkably.

That is, since a plurality of discharge ports are provided to increase the total discharge sectional area, the discharge flow rate can be suppressed. In consideration of the use of artificial closed water areas, it is not preferable to induce a large flow in the water areas by discharging hot waste water. Drainage methods are used to induce a gentle up-down flow due to the effect of buoyancy to improve the water environment in the water area and to avoid the inconvenience of using the current water area.

Furthermore, the drainage means of the present embodiment controls the amount of drainage discharged based on tide information. Specifically, for example, at low tide, the driving force of the pumping pump 102 is increased to increase the amount of seawater to be taken in and increase the amount of drainage from the drainage means. On the contrary, at the time of high tide, the driving force of the pumping pump 102 is reduced to reduce the amount of seawater to be taken. Thereby, it becomes possible to suppress the environmental fluctuation | variation to a closed water area.

That is, if the amount of exhaust heat required from the heat demand facility is constant, the seawater exchange between the inside and outside of the harbor (breakwater) is reduced at low tide, and the temperature rises. When water is taken from outside the closed water area, the drainage temperature can be lowered by increasing the flow rate. Even when the amount of heat is the same at high tide, even if the flow rate is reduced and the drainage temperature is increased, the natural seawater exchange amount is large and the influence is suppressed.

As described above, the hot exhaust water is discharged to the bottom layer in the closed water area. Since the exhausted hot water discharged has a higher temperature than the seawater in the bottom layer, it rises to the surface due to the density difference. And with the rise of the exhaust heat hot water, the surrounding seawater rises as one is pulled, and vertical circulation occurs in the closed water area.

When the surface water having a high oxygen concentration moves to the bottom layer, the poor oxygen state of the bottom layer (that is, the state in which oxygen is deficient) can be improved. Moreover, the point which can reduce the temperature difference accompanying a water depth difference by vertical circulation also leads to the improvement of the poor oxygen state of a bottom layer part.

Moreover, especially under the temperature stratification which is easy to develop in the summer, the temperature of the surface layer is relatively high, but the rise in the water temperature of the surface layer can be suppressed by the vertical circulation. If the surface water temperature can be lowered from the current level, the sea breeze from the inner bay becomes cooler and stronger, and cooling and ventilation in the city center can be expected to be promoted.

As described above, according to the artificial exhaust heat treatment system of the present invention, it is possible to simultaneously realize a countermeasure for the heat island problem associated with the artificial exhaust heat and a countermeasure for the poor oxygen problem in the bay.

Next, paying attention to temperature stratification, which is said to develop in summer, the extent of the energy saving effect of the refrigerator by using low temperature bottom water will be described. Many studies have been conducted in the case where seawater, which is unused energy, is used as cooling water for heat source equipment, but not much research has been conducted focusing on the intake location of seawater to be used. Hereinafter, the energy saving effect at the time of using low temperature bottom layer water is demonstrated.

Assuming the installation of an inverter turbo chiller for the existing district heating and cooling load, the energy saving effect was estimated according to the seawater intake depth. In the reclaimed land in the coastal area of Osaka Bay, in the Cosmo Square area, a simulation was conducted when district heating and cooling as urban infrastructure was commercialized as equipment using seawater. The refrigerator used in the simulation is a Mitsubishi Heavy Industries turbo refrigerator AART-145I (refrigeration capacity 1,500 USRt).

The system configuration used in this simulation is shown in FIG. The “cooling water outlet temperature” and “cooling water inlet temperature” in this figure are the temperatures of the outlet and the inlet for the heat exchanger, and the inlet and outlet are in a reverse relationship for the refrigerator. In this simulation, it is assumed that the heat insulation of the pipe between the heat exchanger and the refrigerator is sufficient, and heat input / output in the pipe path is not considered. (Cooling water outlet temperature of the heat exchanger) approximates (cooling water inlet temperature of the refrigerator), and (Cooling water inlet temperature of the heat exchanger) approximates (cooling water outlet temperature of the refrigerator).

In order to calculate the power consumption, an expression that expresses the COP characteristic of the refrigerator is required. The cooling water inlet temperature of the refrigerator was changed from 12 ° C to 32 ° C in increments of 1 ° C (21 types), and the load factor was changed from 20% to 100% in increments of 10% (9 types) for each temperature. When got the value of COP. Based on this value, regression analysis (second-order approximation) is performed, and the approximate expression obtained is shown.

The approximate correlation multiple correlation R was 9.938 × 10 ⁻¹ .

The formula for calculating power consumption is

Here, H: Waste heat quantity, Q: Cooling load. The cooling load Q is

In addition, the amount of heat H is also the amount of heat used for cooling water.

From the amount of heat exchange on the cooling water side,

The relationship of Formula F is obtained from the heat transfer characteristics of the heat exchanger. Here, K: heat transmission rate (W / (square meter · K)), A: heat transfer area (square meter), delta θm: logarithm average temperature difference (K).

In addition, logarithm average temperature difference delta (theta) m is calculated | required by following Formula.
Regarding the characteristics of the heat exchanger, the relationship between the amount of heat used for cooling water and the KA value was obtained by linear approximation from the operation data of the existing equipment.

In the formula, Cpa, γa, Cpb and γb are known. Va and Vb are determined assuming that the refrigerator used in the simulation is operated independently, and further assuming a case where the rated operation is performed at a difference of 5 ° C. in the chilled water temperature. Approximately 1,000m3 / h). Q is the actual load data in the existing district heating and cooling system, and θ _a1 is the seawater temperature (actual value) measured in this study.

From the above, there are seven unknowns in this simulation: E, H, θa2, θb1, θb2, COP, and KA. By solving these seven simultaneous equations of Formula A to Formula G, the value of power consumption E can be calculated. Asked.

FIG. 5 shows the average seawater temperature on the day of the simulation and the operating time of the centrifugal chiller. The data of seawater temperature used for the simulation was actually measured at the positions of DL-8.65m and DL-2.585 in August and September 2006. In addition, seawater average temperature described in the table is the average value of seawater temperature within the operating time of the centrifugal chiller.

FIG. 6 shows a result of a simulation for calculating power consumption at the existing water intake position (DL-2.585 m) and the bottom water near R1 (DL-3.8 m).

In any day, it was found that the power consumption decreased as the seawater temperature decreased. The power saving rate due to the intake depth being reduced by about 6m is 8.1 to 16.9% in August (water temperature difference 1.84 to 4.08 degrees), and 1.1 to 5.5% in September ( The water temperature difference was 0.23 to 1.29 degrees. On August 12, the seawater temperature difference was 4.08 degrees, so the power saving rate was also very high at 16.9%.

When the water intake depth was lowered by about 6 m, the average water temperature difference during the same period was about 2 ° C., and the average power saving effect was expected to be 12% or more. It was found that even if the average value of the simulation target day in August, excluding the 12th, was taken, an energy saving effect of about 9% was obtained (average water temperature difference 2.06 degrees).

As described above, according to the present invention, paying attention to the temperature stratification that is said to develop in the summer, the energy saving effect of the refrigerator can be remarkably improved by using the low temperature bottom water.

100 Artificial Waste Heat Treatment System 101 Intake Pipe 102 Pump Pump 103 Heat Exchanger 104 Oxygen Supply Equipment 105 Drain Pipe 105A Discharge Port

Claims (3)

Water intake means for taking bottom water from the bottom layer outside the closed water area,
Heat exchange means using bottom water taken by the water intake means as a heat source;
Drainage means for discharging the exhaust heat warm water discharged after being used in the heat exchange means to the bottom layer in the closed water area;
Equipped with a,
An artificial waste heat treatment system in a closed water area in which the drainage means increases the amount of drainage at low tide and decreases the amount of drainage at high tide . Comprising oxygen mixing means for mixing a gas containing oxygen into the exhaust heat hot water discharged after being used in the heat exchange means,
2. The artificial waste heat treatment system in a closed water area according to claim 1, wherein the drainage means discharges high oxygen concentration water mixed with oxygen by the oxygen mixing means to a bottom layer in the closed water area. The artificial waste heat treatment system in a closed water area according to claim 1 or 2, wherein the drain means comprises a drain pipe having a plurality of discharge ports.