KR101489642B1 - Complex fresh water production system using fuel cell apparatus - Google Patents

Abstract

A composite fresh water system using a fuel cell apparatus according to an embodiment of the present invention includes a reverse osmosis part for desorbing raw water by receiving electric energy generated by a fuel cell device, And a membrane distillation part for desalinating the brine discharged from the reverse osmosis device by a membrane distillation process.

Description

[0001] The present invention relates to a complex fresh water production system using a fuel cell device,

One embodiment of the present invention relates to a complex desalination system for desalinating raw water using the exhaust gas and the arrangement of a fuel cell apparatus.

About 97% of the water on the earth is seawater, but it is difficult to use because it is too salty to use for domestic water or industrial water. Desalination of seawater has attracted much attention in the situation where the lack of surface water is supplemented and the water shortage is deepening.

Desalination is a series of processes in which salinity is appropriately removed so that seawater having salinity can be used for drinking water or other purposes. The salt concentration is divided into fresh water, brackish water and sea water depending on the degree of dissolution in the water.

Seawater contains many kinds of salt, so it needs to remove salt to be used as drinking water. To desalinate seawater, a membrane distillation process or a reverse osmosis membrane or a osmosis membrane may be considered.

On the other hand, the fuel cell apparatus is an environmentally friendly energy device, and is attracting attention as an alternative to fossil fuel. The fuel cell device is a power generation device that directly converts chemical energy into electric energy. The fuel containing hydrogen is continuously supplied, and at the same time, the air containing oxygen is continuously supplied, and the electrochemical reaction To directly convert the energy difference before and after the reaction into electric energy.

Such a fuel cell device produces electrical energy and discharges waste heat. A method of desalinating seawater by using electrical energy and waste heat of the fuel cell device can be considered.

It is an object of the present invention to provide a composite fresh water system using a fuel cell apparatus having a higher energy consumption efficiency and a carbon dioxide emission efficiency.

In order to achieve the above object, the present invention provides a combined desalination system using a fuel cell apparatus, comprising: And a membrane distillation part for desalinating the brine discharged from the reverse osmosis device by a membrane distillation process using a reverse osmosis part and an arrangement of the fuel cell device.

According to an embodiment of the present invention, a remineralization part is provided which receives carbon dioxide contained in the exhaust gas of the fuel cell device and is connected to the reverse osmosis part or the membrane distillation part so as to receive at least a part of the generated fresh water .

According to an embodiment of the present invention, a part of the fresh water flowing into the remanization unit is separated into a first fresh water and a second fresh water, and the remanization unit includes a carbon dioxide absorbing unit for reacting with the first fresh water using the carbon dioxide A limestone filter unit that mixes the second fresh water and the first fresh water that has passed through the carbon dioxide absorbing unit and supplies calcium carbonate to the mixed fresh water and a fresh water filter that removes carbon dioxide from the fresh water that has passed through the limestone filter unit And a carbon dioxide removal unit.

According to an embodiment of the present invention, the apparatus may further include a solar heat collection device formed to heat the brine supplied to the membrane distillation section.

According to one example of the present invention, the membrane distillation unit includes a first membrane distillation unit and a second membrane distillation unit, and the solar heat collection apparatus heats brine supplied to the first membrane distillation unit, The apparatus can heat brine supplied to the second membrane distillation unit.

According to an embodiment of the present invention, the apparatus further comprises a heat storage for storing heat collected from the solar heat collecting device, and the heat storage can heat brine supplied to the first membrane distillation unit.

According to an embodiment of the present invention, an electric energy is supplied from the fuel cell device, and organic matter, multivalent ions (suspended solids) contained in the raw water are removed and supplied to the reverse osmosis portion or the membrane distillation portion And a filter unit.

The composite fresh water system using the fuel cell apparatus according to at least one embodiment of the present invention configured as above can increase the thermal efficiency of the entire system by utilizing the waste heat of the fuel cell apparatus, Can be implemented. Further, the carbon dioxide discharged from the fuel cell device can be recycled, and the energy efficiency of the entire system can be increased by driving the reverse osmosis part by using the high efficiency energy produced by the fuel cell device.

Since the membrane distillation section includes a plurality of membrane distillation units and the brine supplied to each membrane distillation unit is heated by different apparatuses, a certain amount of fresh water can be secured according to the amount of sunshine, Can be solved.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a conceptual diagram of a combined desalination system associated with an embodiment of the present invention.
2 is a conceptual diagram of a composite fresh water system according to a first embodiment of the present invention;
3 is a conceptual diagram of a remapping section according to an embodiment of the present invention;
4 is a conceptual diagram of a composite fresh water system according to a second embodiment of the present invention;
5 is a conceptual view of a fuel cell apparatus related to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a composite fresh water system using the fuel cell apparatus according to the present invention will be described in detail with reference to the drawings. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the present specification, the same or similar reference numerals are given to different embodiments in the same or similar configurations. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

1 is a conceptual diagram of a combined desalination system according to an embodiment of the present invention.

The combined fresh water system has a membrane distillation part 130 and a reverse osmosis part 120.

The reverse osmosis part 120 is formed to receive raw water to be pumped through a pump and then discharge saline-free fresh water using a reverse osmosis membrane. The reverse osmosis part 120 may be classified into sea water reverse osmosis or Brackish reverse osmosis.

The reverse osmosis part 120 includes a plurality of vessels, and each vessel may be filled with a plurality of reverse osmosis membranes. The reverse osmosis membrane constituting the reverse osmosis part 120 may be exchanged for a predetermined period (for example, 3 to 5 years). Here, osmotic pressure refers to the pressure caused by a phenomenon in which a solvent is transferred from a lower concentration side to a higher concentration side when two liquids having different concentrations are blocked with a semipermeable membrane. Reverse osmosis refers to the phenomenon in which pure solvent exits from the solution through the semipermeable membrane when a pressure higher than osmotic pressure is applied. The reverse osmosis membrane is a semi-permeable membrane used to cause reverse osmosis.

A seawater desalination plant by reverse osmosis membrane filtration is an ionic material which is dissolved in seawater by semi-permeable membrane (membrane) which is almost exclusion of dissolved ionic substance and pure water passes. In order to separate ionic material from pure water in seawater, a higher pressure than osmotic pressure is required, which is called reverse osmotic pressure, and seawater desalination requires a high pressure of about 40 to 70 bar.

The membrane distillation unit 130 desalinates the raw water using a membrane distillation process. In the membrane distillation process, when an aqueous solution (seawater) having a temperature of about 60 to 90 ° C is passed through a hydrophobic membrane (membrane distillation membrane), a liquid nonvolatile solvent is repelled at the membrane surface and only the vapor phase, The steam phase is formed to condense immediately in the membrane permeation unit to desalinate the raw water. In such a membrane distillation process, the propulsive driving force is a temperature difference, which is accompanied by a temperature difference and a vapor pressure difference to promote phase separation. That is, in the membrane distillation process, a lower temperature than the distillation by the general heating and a lower pressure operating condition than the reverse osmosis are used. In the membrane distillation process, it is necessary to use a porous hydrophobic membrane. As the material of the hydrophobic membrane, PTFE, PP, PVDF and the like can be used.

According to the membrane distillation process, a device for heating seawater to the predetermined temperature is required, and a device for supplying electric energy to the reverse osmosis part 120 is required. With such an apparatus, it is possible to consider using the solar heat collection apparatus 150 as shown in the area where the amount of sunshine is large. As the solar heat collecting device 150, a parabolic trough collector, a linear fresnel system, a solar power tower, and a Dish stirling engine can be used. In the case of using a parabolic trough collector, a method of installing a heat absorbing receptacle at a point where light is concentrated by a reflector and a reflector in a semicylinder, absorbing the heat through the heat medium, and then storing the absorbed heat in the heat storage 140 have. At this time, the steam turbine is operated using some of the collected heat to generate electric energy, and then used for a pump for pressurizing the raw water supplied to the reverse osmosis part 120, and the remaining part of the heat is used to heat the raw water, 130).

However, when the solar collecting device 150 is used as a main heat source and an electric energy source of the complex fresh water system, the efficiency of the generated electric energy is low and the efficiency of the entire fresh water mixed system is lowered. And there is a problem that the amount of fresh water is lowered at night. In addition, since a large area of land is required to construct a solar heat collecting device alone, it is difficult to implement such a combined desalination system in an area where a certain area is proposed.

In order to solve such a problem, the present invention proposes a combined desalination system using a fuel cell apparatus 200. In FIGS. 2 to 4, the concept of a combined desalination system is explained. In FIG. 5, A usable fuel cell device 200 will be described by way of example.

2 is a conceptual diagram of a complex fresh water system according to the first embodiment of the present invention.

Referring to FIG. 2, the complex fresh water system includes a membrane distillation unit 130, a reverse osmosis unit 120, and a fuel cell apparatus 200.

The filter unit 110 may be formed between the raw water supply unit and the reverse osmosis unit to which the raw water is supplied. The filter unit 110 may be configured to remove the organic substances, multivalent ions, or suspended solids included in the raw water and supply the same to the reverse osmosis part 120 or the membrane distillation part 130.

A pressure recovery unit is formed between the filter unit 110 and the membrane distillation unit 130. The pressure recovery unit is configured to recover the pressure of the brine discharged from the filter unit 110 and pressurize the raw water supplied to the filter unit 110.

The reverse osmosis part 120 is formed to receive the raw water that is pumped through the pump after passing through the filter part 110, and then to discharge the desalinated fresh water using the reverse osmosis membrane. The brine having passed through the reverse osmosis part (120) is supplied to the membrane distillation part (130).

The raw water flowing into the reverse osmosis part 120 after passing through the filter part 110 flows through the pump at a high pressure of about 40 to 70 bar. The electric energy for driving the pump is supplied from the fuel cell device 200 . Thus, the high efficiency of the fuel cell apparatus 200 can increase the energy efficiency of the entire system.

The fresh water having passed through the reverse osmosis part 120 is supplied to the remineralization part 160 and the brine is supplied to the membrane distillation part 130. The membrane distillation unit 130 desalinates the raw water using a membrane distillation process. In the membrane distillation process, when an aqueous solution (seawater) having a temperature of about 60 to 90 ° C is passed through a hydrophobic membrane (membrane distillation membrane), a liquid nonvolatile solvent is repelled at the membrane surface and only the vapor phase, The vapor phase is formed to condense immediately in the membrane permeation unit to desalinate the raw water

According to the present invention, the membrane distillation section 130 includes a first membrane distillation unit and a second membrane distillation unit. The first membrane distillation unit is supplied with the brine heated by the solar heat collecting device 150 and the second membrane distilling unit is formed to receive the brine heated by the arrangement of the fuel cell apparatus 200. Fresh water desalinated by the membrane distillation unit 130 is supplied to the remelting unit 160. As described above, the membrane distillation section 130 includes a plurality of membrane distillation units, and the brine supplied to each membrane distillation unit is heated by different apparatuses, so that a certain amount of fresh water can be secured depending on the amount of sunshine, It is possible to solve the problem that the fresh water amount is lowered at night. In addition, the thermal efficiency of the entire system can be increased by utilizing the waste heat of the fuel cell apparatus 200, and a composite fresh water system can be realized with a smaller area.

3 is a conceptual diagram of the remelting unit 160 according to the embodiment of the present invention.

Fresh water having passed through the membrane distillation section 130 or the reverse osmosis part 120 is close to distilled water. Since freshwater produced by seawater desalination has no salt or gas and the total alkalinity expressed by the content of calcium carbonate (ppm as CaCO ₃ ) is about 1 ppm, (CO ₂ ) is dissolved in the atmosphere in contact with the atmosphere, has a low pH value, and corrodes the pipe line in the process of being transported in the water distribution system.

As a result, the produced fresh water has a low pH value, contains oxides produced by corrosion in the piping line, and has a low TDS (Total Dissolved Solid) concentration, making it unavailable as drinking water. In order to prevent such corrosion, the produced drinking water should have a corrosion index of at least 0. Corrosion index refers to the extent to which tap water is corrosive to metal or cement, and generally means that the Langley Index (LI) is used and if it is below 0, it is corrosive to the water pipe.

In order to make the corrosion index to have a value of 0 or more, generally calcium hydroxide [Ca (OH) ₂ ] is injected into drinking water produced from seawater, that is, distilled water and carbon dioxide is further added to increase the alkalinity so that the total alkalinity becomes 50 ppm or more, Is kept constant at about 8 so that the corrosion index has a value of 0 or more.

The present invention thus constitutes a remultiplexer 160 for converting drinking water into drinking water. The remolding section 160 regulates the pH of the fresh water to be suitable for drinking and improves the taste of the water. As shown, the remoulders 160 may include a carbon dioxide absorbing unit 161, a limestone filter unit 162, and a carbon dioxide removing unit 163. Carbon dioxide contained in the exhaust gas of the fuel cell apparatus 200 may be supplied to the remolding unit 160.

Fresh water flowing into the remoulders 160 can be separated to flow through the plurality of pipes. That is, some of the fresh water flowing into the remanufacturing unit 160 can be separated into the first fresh water and the second fresh water.

At this time, the carbon dioxide absorbing unit 161 absorbs the carbon dioxide contained in the flue gas of the fuel cell apparatus 200 and reacts with the first fresh water

The limestone filter unit 162 is formed so that the carbon dioxide-absorbed first fresh water and the second fresh water are mixed to pass therethrough. As a result, calcium carbonate in the limestone reacts with carbon dioxide to form calcium ions (Ca ²⁺ ) and bicarbonate ions HCO ₃ ^1- ) is produced. As a result, the pH of the fresh water can be controlled and the corrosiveness index can be lowered.

The carbon dioxide removing unit 163 supplies air to discharge the excess carbon dioxide remaining in the first and second fresh water passing through the limestone filter unit 162 through the discharge unit.

Thus, the fresh water having passed through the carbon dioxide absorbing unit 161, the limestone filter unit, and the carbon dioxide removing unit 163 can be mixed with other fresh water to produce fresh water meeting the standards of the drinking water.

4 is a conceptual diagram of a composite fresh water system according to a second embodiment of the present invention.

Referring to FIG. 4, the complex fresh water system includes a membrane distillation unit 130, a reverse osmosis unit 120, and a fuel cell apparatus 200.

A filter unit 110 may be formed between the raw water supply unit to which the raw water is supplied and the reverse osmosis membrane. The filter unit 110 may be configured to remove the organic substances, multivalent ions, or suspended solids included in the raw water and supply the same to the reverse osmosis part 120 or the membrane distillation part 130.

A pressure recovery unit is formed between the filter unit 110 and the membrane distillation unit 130. The pressure recovery unit is configured to recover the pressure of the brine discharged from the filter unit 110 and pressurize the raw water supplied to the filter unit 110.

The reverse osmosis part 120 is formed to receive the raw water that is pumped through the pump after passing through the filter part 110, and then to discharge the desalinated fresh water using the reverse osmosis membrane. The brine having passed through the reverse osmosis part (120) is supplied to the membrane distillation part (130).

The raw water flowing into the reverse osmosis part 120 after passing through the filter part 110 flows through the pump at a high pressure of about 40 to 70 bar. The electric energy for driving the pump is supplied from the fuel cell device 200 . Thus, the high efficiency of the fuel cell apparatus 200 can increase the energy efficiency of the entire system.

Fresh water having passed through the reverse osmosis part 120 is supplied to the remolding part 160, and the brine is supplied to the membrane distillation part 130. The brine supplied to the membrane distillation section 130 is heated by the waste heat of the fuel cell apparatus 200. The membrane distillation section 130 desalinates the brine using a membrane distillation process, and the desalinated fresh water is supplied to the remelting section 160. As described above, the remolding unit 160 regulates the pH of the fresh water and lowers the corrosiveness index by using the carbon dioxide contained in the exhaust gas of the fuel cell apparatus 200.

As described above, according to the embodiment of the present invention, the thermal efficiency of the entire system can be increased by utilizing the waste heat of the fuel cell apparatus 200, and a composite fresh water system can be realized with a smaller area. Further, the carbon dioxide discharged from the fuel cell apparatus 200 can be recycled, and the energy efficiency of the entire system can be increased by driving the reverse osmosis part 120 using the high efficiency energy produced by the fuel cell apparatus 200 .

5 is a conceptual diagram of a fuel cell apparatus 200 related to the present invention.

The types of fuel cells include a phosphoric acid fuel cell, an alkaline fuel cell, a proton exchange membrane fuel cell, a molten carbonate fuel cell, a solid oxide Fuel cell (Solid Oxide Fuel Cell), direct methanol fuel cell (Direct Methanol Fuel Cell). The fuel cell types as described above operate by the same principle as fuel, but they are classified according to the type of fuel used, the operating temperature, the catalyst, and the like.

In particular, a molten carbonate fuel cell (MCFC) is operated at a high temperature of 650 ° C or higher, so that the electrochemical reaction rate is high, and nickel can be used instead of a platinum catalyst as an electrode material.

In addition, when the bottoming cycle using the heat recovery steam generator is applied, the heat efficiency of the entire power generation system can be increased to 60% or more by recovering the high-temperature waste heat.

In addition, since the molten carbonate fuel cell is operated at a high temperature, it can be employed as an internal reforming type in which a fuel reforming reaction is simultaneously carried out in a fuel cell stack where an electrochemical reaction occurs.

Since the internal reforming-type molten carbonate fuel cell utilizes the heat generated from the electrochemical reaction in the reforming reaction, which is a direct endothermic reaction without a separate external heat exchanger, the thermal efficiency of the entire system is further increased as compared with the externally reforming molten carbonate fuel cell And the system configuration is simplified at the same time.

The fuel cell apparatus 200 includes a reformer 210 for generating a byproduct containing hydrogen gas and heat by receiving a fuel from the fuel supplier and a fuel supplier for supplying a predetermined amount of fuel, And a stack portion for generating electricity and heat by an electrochemical reaction between hydrogen gas and oxygen supplied separately.

The stack portion may be formed by stacking a plurality of unit cells including a reformer 210, an anode electrode 220, an electrolyte membrane 240, and a cathode electrode 230.

The operation of the fuel cell module as described above is as follows.

First, when fuel and water containing liquefied natural gas (LNG) or methane (CH ₄ ) are supplied to the reformer unit 210, the reformer unit 210 performs steam reforming ) And water gas shift reaction are combined to generate hydrogen gas, reaction heat, and other by-products including water.

CH ₄ + 2H ₂ O - > 4H ₂ + CO ₂

In the stack portion, the hydrogen gas supplied from the reforming unit 210 reacts with oxygen and carbon dioxide supplied to the cathode to form carbonate ions (CO ₃ ^2- ), and the generated carbonate ions (CO ₃ ^{2 -} Causing a chemical reaction to generate electricity, heat and water.

First, the hydrogen gas (H ₂ ) is supplied to the anode (anode) 220 side to form carbonic acid ions (CO ₃ ^{2 -} ). And an electrochemical oxidation reaction takes place to produce water, carbon dioxide and electrons (e-).

H ₂ + CO ₃ ^{2 -} -> H ₂ O + CO ₂ + 2e ^-

In the cathode electrode (aka, air electrode 230), oxygen, carbon dioxide, and electrons supplied from the outside generate an electrochemical reduction reaction to generate carbonate ions (CO ₃ ^{2 -} ), reaction heat, and water. The carbonate ions generated in the cathode electrode 230 move from the cathode electrode 230 to the anode electrode 220 through the electrolyte of the electrolyte membrane 240 located between the cathode electrode 230 and the anode electrode 220, Electrons generated in the anode electrode 220 move through an external circuit while electric energy is generated by movement of electrons. At this time, the electrolyte is normally present in a solid state, but when the fuel cell system is operated normally, the temperature rises to about 650 ° C, and the electrolyte is liquefied.

(1/2) O _{2 +} CO ₂ + 2e ^- -> CO ₃ ^{2 -}

Here, CO ₂ is moved from the cathode electrode 230 to the anode electrode 220 through the electrolyte by an electrochemical reaction mechanism, and is concentrated _.

The composite desalination system using the fuel cell apparatus described above is not limited in the configuration and the method of the embodiments described above but the embodiments can be applied to all or a part of each embodiment Or may be selectively combined.

Claims (7)

A reverse osmosis part for supplying the electric energy generated by the fuel cell device to desalinate the raw water;
A membrane distillation part for desalinating the brine discharged from the reverse osmosis part heated by the arrangement (exhaust heat) of the fuel cell device by a membrane distillation process; And
A remineralization part connected to the reverse osmosis part or the membrane distillation part so as to receive carbon dioxide contained in the exhaust gas of the fuel cell device and receive at least a part of the generated fresh water;
A composite desalination system using a fuel cell system including a fuel cell system. delete The method according to claim 1,
A part of the fresh water flowing into the remanufacturing part is separated into a first fresh water and a second fresh water,
The re-
A carbon dioxide absorption unit that reacts with the first fresh water using the carbon dioxide;
A limestone filter unit for mixing the second fresh water and the first fresh water passed through the carbon dioxide absorbing unit and supplying calcium carbonate to the mixed fresh water; And
And a carbon dioxide removing unit for removing carbon dioxide from the fresh water passing through the limestone filter unit. The method according to claim 1,
Further comprising a solar heat collecting device configured to heat the brine supplied to the membrane distillation unit. 5. The method of claim 4,
Wherein the membrane distillation section comprises a first membrane distillation unit and a second membrane distillation unit,
Wherein the solar heat collection apparatus heats brine supplied to the first membrane distillation unit and the fuel cell apparatus heats brine supplied to the second membrane distillation unit. 6. The method of claim 5,
Further comprising a heat storage for storing heat collected from the solar collector,
And the heat storage heats brine supplied to the first membrane distillation unit. The method according to claim 1,
Further comprising a filter unit that receives electric energy from the fuel cell apparatus and removes organic substances, multivalent ions, or suspended solids contained in the raw water, and supplies the organic substances, multivalent ions, or suspended solids to the reverse osmosis unit or the membrane distillation unit. A composite fresh water system using a fuel cell device.

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