Patent Application
20160097566
This application claims the foreign priority benefit under Title 35, United States Code, §119 (a)-(d) of Japanese Patent Application No. 2014-203409, filed on Oct. 1, 2014 in the Japan Patent Office, the disclosure of which is herein incorporated by reference in its entirety.
The present invention relates to a cooling system using deep seawater.
Deep seawater intake facilities have been operated at a dozen places in Japan, and have also been operated in the United States, France, South Korea, Taiwan and other countries. Among them, the facilities in Japan are mainly for industry use (fishery, agriculture, food, bottled water and the like) of deep seawater, and the number of examples which actively use cold energy is small. However, outside Japan, mainly in isolated islands in the United States and France, large scale plans of district cooling operations using cold energy of deep seawater have been advanced. In these plans, it is common that cold water cooled by heat exchange between the cold water (fresh water) and intake deep seawater (sea water) is supplied to a customer through water conveyance pipe network.
Patent Document 1 describes an air conditioning system, which can cool a heat-exchanged medium by cold energy of deep seawater and further efficiently produce fresh water from the deep seawater.
In a technology described in Patent Document 1, a distance to an air conditioner from an intake port of deep seawater is generally long. More specifically, not only a water intake pipe for pumping up deep seawater, but also a cold water pipe to the customer from a water intake plant with a heat exchanger, to which the pumped-up deep seawater is first supplied, are long. Incidentally, fresh water to which cold energy of deep seawater is supplied in the heat exchanger flows through the cold water pipe.
When circulating the cold water between the customer and the water intake plant, a pipe system is, for example, one way about 2 to 3 km and an amount of retained water is large, and thus a volume required for an expansion tank for absorbing thermal expansion of water due to temperature change exceeds 100 m3 in some cases. The expansion tank is heavy, and it is difficult to secure a realistic installation place while a cost becomes enormous.
Further, although the cold water pipe is filled with fresh water during operation, water filling and drainage operation is required several times for a pipe flushing and the like during test operation. Since fresh water is expensive in island regions, there is a problem that test operation cost is also expensive.
The present invention is an invention to solve the above problems, and an object thereof is to provide a cooling system using deep seawater capable of reducing the cost.
In order to achieve the above object, a cooling system using deep seawater of the present invention is a cooling system using deep seawater, including a pump (for example, water intake pump 2) for pumping up deep seawater from the sea, a heat exchanger for exchanging heat between a coolant and cold energy of the pumped-up deep seawater, a first deep seawater pipe for supplying the deep seawater to the heat exchanger from the pump, and a second deep seawater pipe which is in communication with the first deep seawater pipe and discharges the deep seawater into the sea, wherein the first deep seawater pipe and the second deep seawater pipe are laid in close proximity by a predetermined distance in the ground. Other aspects of the present invention will be described in later embodiments.
According to the present invention, it is possible to reduce cost of a cooling system using deep seawater.
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
In
The deep seawater which is pumped up from a water depth of, for example, 800 m through an water intake pipe 1 by the water intake pump 2 disposed in the water intake plant 20, is supplied to the heat exchanger 3 in the customer's building 30 from the water intake plant 20 through the first deep seawater pipe 10. The deep seawater which has been supplied to the heat exchanger 3 is heat-exchanged with the cold water by the heat exchanger 3, and then the deep seawater is returned through the second deep seawater pipe 11, to be discharged into the sea.
In order to suppress temperature rise of the deep seawater supplied to the customer's building 30, a pipe with heat insulation is used as the first deep seawater pipe 10. A HDPE pipe (high-density polyethylene pipe) which is insulated with heat insulating material is used as the pipe with heat insulation. Specifically, the HDPE pipe and a rigid polyurethane insulating material are integrated with a special adhesive, and are covered with the HDPE on the outside thereof. A HDPE pipe without heat insulating material is used as the second deep seawater pipe 11.
Further, both of the first deep seawater pipe 10 and the second deep seawater pipe 11 are buried in the ground in order to suppress thermal expansion and contraction (dot area in
Effects of burying the pipes as shown in
Returning to
Pressure loss of the water intake pipe 1 is obtained by the following calculation formula (1).
Δh=10.67×C−1.85×D−4.87×Q1.85×L (1)
Here, Δh is friction head loss (m), C is flow rate coefficient, D is pipe diameter (m), Q is flow rate (m3/s), and L is pipe length (m). When it is assumed that C=150, D=0.8 m, Q=0.4 m3/s, and L=2500 m, pressure loss Δh of the water intake pipe 1 is equal to 1.4 m. By installing the water intake pump 2 in a position of −4.0 m from the MSL in consideration of this value (1.4 m) and pressure loss (for example, assumed to be 2 m) of a water intake port, a strainer and the like, the water pressure (water head pressure) exceeding the pressure loss of the water intake pipe 1, the water intake port, the strainer and the like is always applied to the suction port of the water intake pump 2, and thus it is possible to reduce the power of the water intake pump 2, thereby reducing the running cost. Note that, since the pressure loss Δh is proportional to the pipe length L if an amount of water intake is constant, it is necessary to lower the position of the water intake pump 2 (lower a position of a pump chamber), as the water intake pipe 1 is longer.
On the other hand, a water supply pipe (the first deep seawater pipe 10) for supplying the deep seawater to the customer's building 30 from the water intake pump 2 is desirable to increase flow rate by reducing diameter in consideration of cost and temperature rise during water supply. However, when increasing the flow rate, an abnormal vibration is generated by turbulence in the pipe while the pressure loss is increased, and thus the running cost of the pump is increased.
Therefore, the flow rate of the deep seawater pumped by the water intake pump 2 in the pipe is generally set to about 2 to 2.5 m/s from the viewpoint of not generating abnormal vibration. In the present embodiment, when the flow rate is set to the above value, a diameter of the water supply pipe is 630 mmφ, and can be smaller than a diameter of the water intake pipe 1.
In contrast to the comparative example in
(1) Since the second deep seawater pipe 11 is provided in place of the second cold water pipe 6 between the water intake plant 20 and the customer's building 30, an amount of the expensive HDPE pipes with heat insulation is reduced, and construction costs are reduced. Meanwhile, since the temperature of the deep seawater which is discharged into the sea through the second deep seawater pipe 11 is raised by receiving heat from the ground, it is possible to discharge the deep seawater into the shallower sea. This allows a water discharge pipe to be short, and thus an effect of reducing the power of the pump is obtained while the construction costs are reduced.
(2) By burying the second deep seawater pipe 11 over the first deep seawater pipe 10, the second deep seawater pipe 11 receives the heat from the ground while the first deep seawater pipe 10 is prevented from being heated by the heat from the ground.
(3) Although the deep seawater filled in the first deep seawater pipe 10 and in the second deep seawater pipe 11 is thermally expanded due to temperature change, an expansion tank is not required because an end of the second deep seawater pipe 11 is open to the sea. A volume required for the expansion tank of the cold water pipe system in the customer's building 30 becomes small. Further, since the deep seawater for filling the pipes is obtained from the sea, fresh water for filling or flushing is not required. As a result, in island regions where fresh water is precious, impact on water resources is also reduced.
Although the air conditioning equipment 8 using the cold water is shown as an example for the customer's building 30 in the present embodiment, the deep seawater can be applied to multistage use. For example, the cold energy of the deep seawater is used for air conditioning, and the deep seawater after using the cold energy may be further used in a seawater desalination device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-203409 | Oct 2014 | JP | national |
