KR20210067116A - Hybrid power generation system using waste heat and controlling device and method thereof - Google Patents

Abstract

The present invention relates to a hybrid power generation system using waste heat, a device for controlling the same, and a method therefor. The hybrid power generation system using waste heat according to an embodiment of the present invention comprises: a brackish water chamber for storing and supplying brackish water; a heat exchanger for heating and supplying the brackish water supplied from the brackish water chamber through heat exchange using power generation waste heat; a membrane distiller for supplying, by separating brine and fresh water, the brackish water heated by the heat exchanger through a membrane distillation process using the brackish water heated by the heat exchanger; and a reverse electrodialysis machine for circulating brine and fresh water separated by the membrane distiller and supplied between ion exchange membranes to generate electricity according to the difference in salinity concentration, and for circulating brine and fresh water with different salinity concentrations to the brackish water chamber. Accordingly, power generation efficiency can be increased by using low grade waste heat which is generated from a fuel battery, and produce clean energy.

Description

Hybrid power generation system using waste heat, control device thereof, and method thereof {HYBRID POWER GENERATION SYSTEM USING WASTE HEAT AND CONTROLLING DEVICE AND METHOD THEREOF}

The present invention relates to a hybrid power generation system using waste heat, a control device thereof, and a method thereof, and more particularly, to separate brine and fresh water by utilizing waste heat generated during operation of a fuel cell in a membrane distillation process, and to separate brine and After generating electricity by supplying fresh water to the reverse electrodialysis process, the brackish water discharged through the reverse electrodialysis process is supplied back to the membrane distillation process to maximize power generation efficiency using low-grade waste heat generated from the fuel cell and clean It relates to a hybrid power generation system using waste heat for producing energy, an apparatus for controlling the same, and a method therefor.

A fuel cell is a device that generates electric energy by electrochemically reacting fuel with an oxidizing agent.

The power generation device using such a fuel cell is a fuel reformer that converts general fuel into a gas containing a lot of hydrogen required by the fuel cell, and a fuel that generates direct current electricity and heat using hydrogen and oxygen coming from the fuel reformer. A fuel cell may include a power converter that converts DC power generated from the fuel cell into AC power.

In addition, the fuel cell is a molten carbonate fuel cell (MCFC), a polymer electrolyte fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a direct methanol fuel cell ( Various types of fuel cells such as Direct Methanol Fuel Cell (DMFC) and Phosphoric Acid Fuel Cell (PAFC) have been developed.

In particular, a phosphoric acid fuel cell (PAFC) is a fuel cell using liquid phosphoric acid as an electrolyte, and when the operating temperature of 150 to 200° C. is reached, water generated as a reaction product can be converted into steam and used for heating air or water.

These phosphoric acid fuel cells produce electricity and heat at the same time. Therefore, the phosphoric acid type fuel cell has a power generation efficiency of around 43% during pure power generation, but a maximum efficiency of 90% can be expected when waste heat is used.

1 is a view for explaining energy calculation of a phosphoric acid fuel cell. Referring to FIG. 1 , waste heat of 120°C, which is a high-grade heat output, can be utilized as hot water supply, etc., but waste heat of 60°C, which is a low-grade heat output, currently has no usable field.

Therefore, there is a need for a method for maximizing power generation efficiency and producing clean energy by utilizing low-grade waste heat in the phosphoric acid fuel cell.

Korean Patent Publication No. 10-1190610 (Registered on Oct. 8, 2012)

It is an object of the present invention to separate brine and fresh water by using waste heat generated during operation of a fuel cell in a membrane distillation process, supply the separated brine and fresh water to the reverse electrodialysis process to generate electricity, and then perform the reverse electrodialysis process Hybrid power generation system using waste heat, its control device, and its method for maximizing power generation efficiency and producing clean energy using low-grade waste heat generated from the fuel cell by supplying the brackish water discharged through the membrane distillation process back to the membrane distillation process is to provide

A hybrid power generation system using waste heat according to an embodiment of the present invention includes: a brackish chamber for storing and supplying brackish water; a heat exchanger for heating and supplying the brackish water supplied from the brackish water chamber through heat exchange using the power generation waste heat; a membrane distiller for separating and supplying brackish water and fresh water heated by the heat exchanger through a membrane distillation process using the brackish water heated by the heat exchanger; and a reverse electrodialysis machine for circulating the brine and fresh water separated by the membrane distiller and supplied between the ion exchange membranes to generate electricity according to the difference in salinity, but with different salinity and fresh water to the brackish water chamber; may include

The power generation waste heat may be low-grade waste heat of fuel cell exhaust water.

The membrane distillation unit includes: a membrane distillation chamber having a hydrophobic polymer separation membrane to perform a membrane distillation process; a brine chamber for storing high-concentration brackish water separated on one side of the membrane distillation chamber based on the hydrophobic polymer separation membrane; and a freshwater chamber for storing a condensing unit separated on the other side of the membrane distillation chamber based on the hydrophobic polymer separation membrane.

The reverse electrodialysis machine comprises a plurality of cell regions by alternately arranging a cation exchange membrane and an anion exchange membrane between the anode and the cathode, wherein the plurality of cell regions include an anode solution supplying electrons through an oxidation reaction anode cell; and a reduction electrode cell including a cathode solution receiving electrons through a reduction reaction.

The anode solution and the cathode solution may be of a fixed type that does not circulate between the anode cell and the cathode cell, and may include a redox pair.

According to an embodiment, a control device for determining the operating state of the membrane still and the reverse electrodialysis machine; may further include.

The control device may be to determine the operating state of the membrane distiller by calculating a flow rate ratio, which is a ratio of a supply flow rate and a discharge flow rate of the membrane distiller, and checking whether the flow rate ratio is within an allowable error range.

The membrane distillation unit, MD supply flow rate measuring sensor for measuring the total flow rate of brackish water supplied from the heat exchanger; and a MD discharge flow rate measuring sensor for measuring the combined flow rate of the brine flow rate and the fresh water flow rate discharged to the reverse electrodialysis machine, wherein the control device further comprises, the supply flow rate of the membrane distiller through the MD supply flow rate measuring sensor and measuring the discharge flow rate of the membrane distiller through the MD discharge flow rate measuring sensor.

The control device may be to determine the operating state of the reverse electrodialysis machine by calculating the flow rate ratio, which is the ratio of the supply flow rate and the discharge flow rate of the reverse electrodialysis machine, and checking whether the flow rate ratio is within an allowable error range.

The reverse electrodialysis machine, a RED supply flow rate measuring sensor for measuring the combined flow rate of the brine flow rate and the fresh water flow rate supplied from the membrane distiller; and a RED discharge flow rate measurement sensor for measuring the total rider flow rate discharged to the rider chamber; further comprising, wherein the control device measures the supply flow rate of the reverse electrodialysis machine through the RED supply flow measurement sensor, the It may be to measure the discharge flow rate of the reverse electrodialysis machine through the RED discharge flow measurement sensor.

The control device may be to constantly maintain the water level levels of the nose chamber and the brine chamber.

The control device is configured to open a make-up valve between the nose chamber and the brine chamber to supply brine from the brine chamber to the brine chamber by confirming that the water level level of the brackish chamber is less than a predetermined threshold. It could be to control.

The control device may be to discharge the brine stored in the brine chamber to the outside by opening a discharge valve of the brine chamber by checking whether the water level level of the brine chamber is equal to or greater than a predetermined threshold value.

In addition, the control method of a hybrid power generation system using waste heat according to an embodiment of the present invention is a control method of a hybrid power generation system constituting a circulating closed loop of a brackish chamber, a heat exchanger, a membrane still and a reverse electrodialysis machine, the determining an operating state of the membrane distiller or the reverse electrodialysis machine by using a flow rate ratio that is a ratio of a supply flow rate and a discharge flow rate of the membrane distiller or the reverse electrodialysis machine; It may include; a reporting step of reporting the operating state of the hybrid power generation system according to the determination of the operating state of the membrane still or the reverse electrodialysis machine.

The determining may include: calculating a flow rate ratio, which is a ratio of the supply flow rate and the discharge flow rate, by checking the supply flow rate and the discharge flow rate of the membrane distiller or the reverse electrodialysis machine; and checking whether the flow rate ratio is within a preset tolerance range.

According to an embodiment, before determining the operating state of the film still, checking whether the water level level of the nose chamber is less than a predetermined threshold value; and supplying brine from the brine chamber included in the membrane still to the brine chamber when the water level level of the brine chamber is less than the threshold value.

after determining the operating state of the membrane still, confirming whether the water level level of the brine chamber is equal to or greater than a predetermined threshold value; and discharging the brine from the brine chamber to the outside when the water level level of the brine chamber is equal to or greater than a threshold value.

In addition, the control device according to an embodiment of the present invention, the control device of the hybrid power generation system constituting the circulating closed loop of the brackish chamber, the heat exchanger, the membrane still and the reverse electrodialysis machine, at least one processor; and a memory for storing computer readable instructions, wherein the instructions, when executed by the at least one processor, cause the control device to control the supply flow rate and the output flow rate of the membrane still or the reverse electrodialysis machine. To determine the operating state of the membrane still or the reverse electrodialysis machine using the flow rate ratio, which is a ratio, and to report the operating state of the hybrid power generation system according to the determination of the operating state of the membrane still or the reverse electrodialysis machine can

The instructions, when executed by the at least one processor, cause the control device, when determining the operating state of the membrane still or the reverse electrodialysis machine, the supply flow rate and the discharge flow rate of the membrane still or the reverse electrodialysis machine to calculate the flow rate ratio, which is the ratio of the supply flow rate and the discharge flow rate, by checking , and it may be to check whether the flow rate ratio is included within a preset tolerance range.

The instructions, when executed by the at least one processor, cause the control device to check whether the water level in the nose chamber is less than a predetermined threshold before determining the operating state of the film still, If the water level level of the brackish chamber is less than the threshold value, it may be to supply brine from the brine chamber included in the membrane still to the brackish chamber.

The instructions, when executed by the at least one processor, cause the control device to check whether the water level level of the brine chamber is equal to or greater than a predetermined threshold after determining the operating state of the membrane still, and If the water level level of the brine chamber is equal to or greater than a threshold value, the brine in the brine chamber may be discharged to the outside.

The present invention uses waste heat generated during operation of a fuel cell in a membrane distillation process to separate brine and fresh water, and supplies the separated brine and fresh water to the reverse electrodialysis process to produce electricity, and then through the reverse electrodialysis process By supplying the discharged brackish water back to the membrane distillation process, it is possible to maximize power generation efficiency and produce clean energy using low-grade waste heat generated from fuel cells.

In addition, the present invention can prevent foreign substances that may cause fouling of the separation membrane from entering the system in advance through the circulating closed-loop process configuration, and also reduce operating costs because additional solvents are not required. have.

In addition, the present invention does not require the supply of additional solvents (brine, fresh water, brackish water) by fusing individual processes and using them as one, and there is no restriction on location because the system can be provided in the form of a package.

In addition, the present invention can control the composition and concentration of brine in the closed loop process.

In addition, the present invention can be applied by selecting an optimal combination that does not affect the durability of the separation membrane by changing the solvent or solute in the cyclic loop process.

In addition, the present invention integrates and uses the existing individual processes, the membrane distillation process and the reverse electrodialysis process, in one piece, so that the chamber is configured in hardware in the connection between the two processes and the control logic linked between the two processes can be reflected.

1 is a view for explaining energy calculation of a phosphoric acid fuel cell;
2 is a view showing a hybrid power generation system using waste heat according to an embodiment of the present invention;
Figure 3 is a view showing the power production according to the change in the concentration of brine;
Figure 4 is a view showing the power production according to the change in the flow rate of salt water and fresh water;
5 is a view showing the power production according to the change in the concentration of the electrode solution;
6 is a view showing a control method of a hybrid power generation system using waste heat according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, detailed descriptions of well-known functions or configurations that may obscure the gist of the present invention in the following description and accompanying drawings will be omitted. Also, it should be noted that throughout the drawings, the same components are denoted by the same reference numerals as much as possible.

The terms or words used in the present specification and claims described below should not be construed as being limited to their ordinary or dictionary meanings, and the inventors should appropriately define their own inventions in terms of the best way to describe them. Based on the principle that it can be done, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all of the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be equivalents and variations.

In the accompanying drawings, some components are exaggerated, omitted, or schematically illustrated, and the size of each component does not fully reflect the actual size. The present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

In the entire specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. In addition, when a part is said to be "connected" with another part, it includes not only the case where it is "directly connected" but also the case where it is "electrically connected" with another element interposed therebetween.

The singular expression includes the plural expression unless the context clearly dictates otherwise. Terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification is present, and includes one or more other features, number, or step. , it should be understood that it does not preclude in advance the possibility of the existence or addition of an operation, component, part, or combination thereof.

Also, as used herein, the term “unit” refers to a hardware component such as software, FPGA, or ASIC, and “unit” performs certain roles. However, "part" is not meant to be limited to software or hardware. A “unit” may be configured to reside on an addressable storage medium and may be configured to refresh one or more processors. Thus, by way of example, “part” includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays and variables. The functionality provided within components and “parts” may be combined into a smaller number of components and “parts” or further divided into additional components and “parts”.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the embodiments of the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

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

2 is a view showing a hybrid power generation system using waste heat according to an embodiment of the present invention.

As shown in FIG. 2 , the hybrid power generation system using waste heat (hereinafter referred to as a 'hybrid power generation system', 100) according to an embodiment of the present invention is a membrane distillation (membrane distillation, MD) process to separate brine and fresh water, supply the separated brine and fresh water to the Reverse ElectroDialysis (RED) process to produce electricity, and then membrane distill the brackish water discharged through the reverse electrodialysis process. By supplying it back to the process, it is possible to maximize power generation efficiency and produce clean energy by using the low-grade waste heat generated from the fuel cell.

As such, the hybrid power generation system 100 constitutes a circulation-type closed loop process by the flow of salt water, fresh water, and brackish water. Here, the division of salt water, fresh water, and brackish water classifies water quality according to the concentration of salt. That is, salt water is a solution with a salt content of 35,000 mg/L or more, and fresh water is a solution with a salt content of 0 to 1,000 mg/L, and brackish water ) denotes a solution with a salt content of 1,000 to 10,000 mg/L. This is the classification of water quality according to the salt concentration by the US Geological Survey.

In addition, the hybrid power generation system 100 describes a case in which electric power is generated using waste heat generated from a fuel cell, but the present invention is not limited thereto, and it is also applicable to a case where waste heat generated from an incinerator is used.

In addition, the hybrid power generation system 100 may be configured to include a brackish chamber 110 , a heat exchanger 120 , a membrane still 130 , and a reverse electrodialysis machine 140 . The hybrid power generation system 100 further includes a control device (not shown).

First, the control device may adjust the flow rates of fresh water, salt water, and brackish water to enable continuous operation of the hybrid power generation system 100 . The control device includes at least one processor (not shown) and a memory (not shown) for storing computer readable instructions, wherein the computer readable instructions stored in the memory by the at least one processor are When executed, the control method of the hybrid power generation system 100 according to the embodiment of the present invention may be performed.

Next, as the hybrid power generation system 100 forms a circulating closed loop, the rider chamber 110 receives and stores the radix from the reverse electrodialysis machine 140 connected to the front end, and stores the stored radix by a heat exchanger connected to the rear end. (120) is supplied.

The brackish chamber 110 includes a makeup valve 111 for controlling the brine supplied from the brine chamber 132, a first drain valve 112 for discharging the brackish water to the outside, the chamber It includes a rider water level sensor 113 for measuring the water level level of the rider stored in the.

At this time, the control device maintains the water level level of the nose chamber 110 at a preset threshold level. Here, the threshold value may be set at a level of 50% from the total water level level of the nose chamber 110 .

To this end, the control device measures the water level level of the nose chamber 110 using the nose water level sensor 113.

And, when the water level level of the nose chamber 110 is less than a preset threshold, the control device controls the makeup valve 111 to an open state. In this case, the brine stored in the brine chamber 132 is supplied to the brackish chamber 110 .

In addition, the control device controls the makeup valve 111 to a closed state when the water level level of the nose chamber 110 is greater than or equal to a preset threshold as the brine is supplied to the nose chamber 110 . In this case, the brine stored in the brine chamber 132 is supplied to the brackish chamber 110 is stopped.

In addition, the control device may control the opening/closing state of the first discharge valve 112 according to the water level level of the nose chamber 110 . A detailed description thereof will be omitted because it can be easily understood by those skilled in the art.

Next, the heat exchanger 120 heats the brackish water supplied from the brackish water chamber 110 connected to the front end through heat exchange using the generated waste heat, and then supplies the heated brackish water to the membrane distiller 130 connected to the rear end. Here, the power generation waste heat is waste heat discharged from a power generation system such as a fuel cell, and has a temperature range of 60 to 120°C. That is, the power generation waste heat may be low-grade waste heat of fuel cell exhaust water.

At this time, in the heat exchanger 120, as the brackish water supplied from the brackish chamber 110 connected to the front end naturally moves to the membrane distiller 130 connected to the rear end, the heat exchange process by the power generation waste heat occurs naturally. That is, the heat of the power generation waste heat (high-temperature fluid) is transferred to the brackish water (low-temperature fluid) with the heat transfer surface of the heat exchanger 120 interposed therebetween, and the temperature of the brackish water rises.

In addition, when the brackish water heated by the heat exchanger 120 is supplied to the membrane distillation unit 130 , it may be supplied through the first pump P1 installed between the heat exchanger 120 and the membrane distillation unit 130 . This first pump (P1) can be constantly pressurized to improve the performance of the film distillation process made in the film distillation unit (130).

Next, the membrane distiller 130 converts thermal energy into chemical energy using a hydrophobic polymer separation membrane, which is a hydrophobic porous membrane, and is generated by the temperature difference between both sides of the separation membrane due to heated brackish water. Using the change, water is evaporated, moved, and condensed through the micropores on the membrane surface to separate brackish water and fresh water.

That is, the heated brackish water generates a temperature difference in the process of moving through the micropores on the surface of the separation membrane, and is vaporized on the surface of the separation membrane by the difference in vapor pressure and partial pressure induced by the temperature difference. When the vapor passes through the separation membrane and moves to the opposite side, it is converted into condensed water (ie, fresh water).

The membrane distiller 130 is provided with a hydrophobic polymer separation membrane to store the high-concentration brackish water (that is, brine) separated on one side of the membrane distillation chamber 131 in which the membrane distillation process is performed, and the membrane distillation chamber 131 based on the separation membrane. It includes a brine chamber 132 for, and a freshwater chamber 133 for storing condensed water (ie, fresh water) separated on the other side of the membrane distillation chamber 131 based on the separation membrane.

Here, one side of the membrane distillation chamber 131 corresponds to a distiller, and the other side of the membrane distillation chamber 131 corresponds to a condenser. So, when the steam moves to the other side of the membrane distillation chamber 131, the brackish water is changed to brine because the salt concentration of the brackish water itself increases.

In addition, the membrane distiller 130 may further include an MD supply flow rate measuring sensor (MD_in) and MD discharge flow rate measuring sensor (MD_out1, MD_out2).

At this time, the control device calculates the 'ratio of the supply flow rate and the discharge flow rate' (hereinafter referred to as a 'flow rate ratio') of the membrane distiller 130 to determine whether the membrane distiller 130 operates normally.

Here, the flow rate ratio can be expressed as a supply flow rate/discharge flow rate, and is calculated as '1' if the supply flow rate and the discharge flow rate are the same. When the flow rate ratio when the supply flow rate and the discharge flow rate are the same as the reference flow rate, the allowable error range of the flow rate ratio in the membrane distiller 130, which can be viewed as a normal operating range, may be, for example, ±10%. . That is, the allowable error range of the flow rate ratio in the membrane distiller 130 is equal to the reference flow rate-0.1 (ie, 0.9) < flow rate ratio < reference flow rate + 0.1 (ie, 1.1).

That is, the control device determines that the membrane distiller 130 operates normally when the flow rate ratio of the membrane distillation unit 130 falls within the allowable error range.

Specifically, the control device can check the supply flow rate of the membrane distiller 130 by using the MD supply flow measurement sensor MD_in, and discharge the membrane distiller 130 using the MD exhaust flow measurement sensors MD_out1 and MD_out2. flow can be checked. Here, the supply flow rate of the membrane distiller 130 is the total brackish water flow rate supplied from the heat exchanger 120 , and the discharge flow rate of the membrane distiller 130 is the sum of the brine flow rate and the fresh water flow rate discharged from the membrane distiller 130 . .

Then, after calculating the flow rate ratio using the supply flow rate and the discharge flow rate of the membrane distiller 130, the control device checks whether the flow rate ratio is included within the allowable error range.

At this time, the control device determines that the membrane distiller 130 operates normally when the corresponding flow rate ratio is included within the allowable error range, and if the corresponding flow rate ratio is not included within the allowable error range, the membrane distiller 130 operates abnormally. judge to be The control device may notify the system administrator when an abnormal operation of the membrane distiller 130 occurs. Accordingly, the system manager checks whether the membrane distiller 130 leaks, or whether the pump is operating.

Such a control device may be performed according to a preset time (eg, 10 minutes) for the process of determining whether the membrane distiller 130 operates normally.

On the other hand, the membrane distiller 130 is a separation membrane process that can be operated at a lower pressure than the general reverse osmosis method, and can separate brackish water and fresh water by the difference in vapor pressure and partial pressure, and entrain entrainment as in general distillation (Distillation). entrainment) does not occur.

In addition, the brine chamber 132 includes a second discharge valve 132a for discharging the brine to the outside, and a brine level sensor 132b for measuring the level of the brine stored in the chamber.

At this time, the control device maintains the water level level of the brine chamber 132 at a preset threshold level. Here, the threshold value may be set at a level of 70% from the total water level level of the nose chamber 110 .

To this end, the control device measures the water level of the salt water chamber 132 using the salt water level sensor (132b).

In addition, the control device controls the second discharge valve 132a to an open state when the water level level of the brine chamber 132 is equal to or greater than a preset threshold value. In this case, the brine stored in the brine chamber 132 may be supplied to the brackish chamber 110 or discharged to the outside.

In addition, when the water level of the brine chamber 132 is less than a preset threshold as the brine is discharged from the brine chamber 132 , the control device controls the second discharge valve 132a to a closed state. In this case, the brine stored in the brine chamber 132 is stopped discharged.

The brine chamber 132 supplies brine to the reverse electrodialysis machine 140 through a brine flow path, and the fresh water chamber 133 supplies fresh water to the reverse electrodialysis machine 140 through a fresh water flow path.

At this time, the brine supplied from the brine chamber 132 and the fresh water supplied from the fresh water chamber 133 may be supplied to the reverse electrodialysis machine 140 through the second pump P2 and the third pump P3, respectively.

Next, the reverse electrodialysis machine 140 is generated by using the difference in salinity of salt water and fresh water, between the positive electrode (anode) 141 and the negative electrode (cathode) 142 of the (+) pole. A cation-exchange membrane (C) and an anion-exchange membrane (A) are alternately arranged in each other to form a plurality of cell regions.

The plurality of cell regions includes an anode cell 141a and a cathode cell 142a. Here, the anode cell 141a includes an anode solution that supplies electrons through an oxidation reaction, and the cathode cell 142a includes a cathode solution that receives electrons through a reduction reaction.

The anode solution and the cathode solution, that is, the electrode solution, the surplus or deficiency of electrons is switched according to the entry and exit of positive ions, and the anode 141 and the cathode 142 and the reduction electrode 142 can flow by the potential difference generated at this time. let there be

Specifically, the reverse electrodialysis machine 140 alternately flows brine and fresh water between the ion exchange membrane, so that Na+ ions and Cl- ions dissolved in the brine move to the fresh water through the ion exchange membrane and convert the chemical energy generated into electrical energy. converted to generate electricity. That is, the reverse electrodialysis machine 140 induces a chemical potential difference by using the difference in salinity of salt water and fresh water and the separation of Na+ ions and Cl- ions using an ion exchange membrane, and a redox couple material. Converts a chemical potential difference into an electrical potential difference using the to produce electricity.

And, the anode solution and the cathode solution is a fixed type that does not circulate between the anode cell 141a and the cathode cell 142a, and may include a redox pair that is a ^{Fe 2+} /Fe ^{3+ complex.}

In addition, the anode solution and the cathode solution are preferably in a saturated state at room temperature to obtain high output and to enable long-term operation.

In addition, the cation exchange membrane (C) and the anion exchange membrane (A) are alternately installed between the anode cell 141a and the cathode cell 142a to form a plurality of flow paths.

On the other hand, in the reverse electrodialysis machine 140, the brine and fresh water are supplied by crossing between the ion exchange membranes through a pair of passages composed of a salt water passage and a fresh water passage.

Fresh water is supplied to the fresh water passage and brine is supplied to the salt water passage. Then, cations and anions move through the ion exchange membrane. At this time, fresh water becomes brackish water with a high salinity concentration, and salt water becomes brackish water with a low salinity concentration. The salt water and fresh water are discharged to the outside, are mixed into one flow path, and move to the brackish chamber 110 .

As described above, the brackish water collected in the brackish chamber 110 leads to a flow supplied to the membrane distiller 130 again.

In addition, the reverse electrodialysis machine 140 may further include a RED supply flow rate measurement sensor (RED_in1, RED_in2) and a RED discharge flow rate measurement sensor (RED_out).

At this time, the control device determines whether the reverse electrodialysis machine 140 operates normally by calculating the ratio of the supply flow rate and the discharge flow rate, that is, the flow rate ratio of the reverse electrodialysis machine 140 .

As described above, the flow rate ratio can be expressed as a supply flow rate/discharge flow rate, and is calculated as '1' if the supply flow rate and the discharge flow rate are the same. When the flow rate ratio when the supply flow rate and the discharge flow rate are the same as the reference flow rate, the allowable error range of the flow rate ratio in the reverse electrodialysis machine 140, which can be viewed as a normal operating range, can be, for example, ±15%. have. That is, the tolerance range of the flow rate ratio in the reverse electrodialysis machine 140 is equal to the reference flow rate -0.15 (ie, 0.85) < flow rate ratio < reference flow rate + 0.15 (ie 1.15).

That is, the control device determines that the reverse electrodialysis machine 140 operates normally when the flow rate ratio of the reverse electrodialysis machine 140 falls within the allowable error range.

Specifically, the control device can check the supply flow rate of the reverse electrodialysis machine 140 using the RED supply flow measuring sensors (RED_in1, RED_in2), and the reverse electrodialysis machine 140 using the RED discharge flow measuring sensor (RED_out). You can check the discharge flow of Here, the supply flow rate of the reverse electrodialysis machine 140 is the sum of the brine flow rate and the fresh water flow rate supplied from the membrane distiller 130 , and the discharge flow rate of the reverse electrodialysis machine 140 is the total flow rate discharged from the reverse electrodialysis machine 140 . is the brackish flow.

Then, the control device calculates the flow rate ratio using the supply flow rate and the discharge flow rate of the reverse electrodialysis machine 140, and then checks whether the flow rate ratio is included within the allowable error range.

At this time, the control device determines that the reverse electrodialysis machine 140 operates normally if the flow rate ratio is within the tolerance range, and if the flow rate ratio is not included within the tolerance range, the reverse electrodialysis machine 140 is abnormal. judged to be working. The control device may notify the system administrator in case of abnormal operation of the reverse electrodialysis machine 140 . Accordingly, the system administrator will check whether the separator of the reverse electrodialysis machine 140 leaks, whether the electrode solution is circulated, whether the concentration of the electrode solution is lowered, whether the pump is operating, and the like.

On the other hand, the reverse electrodialysis machine 140 changes the concentration of the supplied brine (Experimental Example 1, see Fig. 3), the supplied brine and fresh water flow rate change (Experimental Example 2, see Fig. 4), the change in the concentration of the electrode solution (Experimental Example) 3, see Fig. 5) can be adjusted to improve performance. In addition, there is an optimum value according to the flow ratio of salt water and fresh water and temperature.

Figure 3 is a view showing the power production according to the change in the concentration of brine, Figure 4 is a view showing the power production according to the change in the flow rate of brine and fresh water, Figure 5 is a view showing the power production according to the change in the concentration of the electrode solution.

[Experimental Example 1]

Referring to FIG. 3 , in Experimental Example 1, power production was measured while changing the salt water concentration. At this time, the active area of the ion exchange membrane is 7 cm × 10 cm, the number of cells of the reverse electrodialysis machine 140 is 60 cells, the brine flow rate and fresh water flow rate are 150 cc/min, and the electrode solution concentration is 50 mM.

Experimental parameters are brine concentration, 3.5wt%, 7.0wt%, 10.5wt%, 14.0wt%.

The experimental result is 0.4~0.9W (0.95~2.14 W/m ² ) in unit system power production.

[Experimental Example 2]

Referring to FIG. 4 , in Experimental Example 2, electricity production was measured while changing the flow rates of salt water and fresh water. At this time, the active area of the ion exchange membrane is 7 cm × 10 cm, the number of cells in the reverse electrodialysis machine 140 is 60 cells, the saline concentration is 10 wt%, and the electrode solution concentration is 50 mM.

Experimental parameters are brine and freshwater flow rates, which are 150cc/min, 200cc/min, 250cc/min, 300cc/min, 350cc/min.

The experimental result is 0.79~1.68W (1.88~4.00 W/m ² ) in unit system power production.

[Experimental Example 3]

Referring to FIG. 5 , in Experimental Example 3, power production was measured while changing the electrode solution concentration. At this time, the active area of the ion exchange membrane is 7 cm × 10 cm, the number of cells of the reverse electrodialysis machine 140 is 60 cells, the brine concentration is 10 wt%, and the brine and fresh water flow rates are 150 cc/min.

Experimental parameters are the concentration of the electrode solution, 50mM, 70mM.

The experimental result is 0.79∼0.94W (1.88∼2.24 W/m ² ) of unit system power production.

6 is a view showing a control method of a hybrid power generation system using waste heat according to an embodiment of the present invention.

The control device adjusts the flow rates of salt water, fresh water, and brackish water to enable continuous operation of the hybrid power generation system 100 . In this case, the control device tests the characteristics of the system in advance and applies the results based on the results. Accordingly, the presented value may be changed according to the capacity of the chamber or the capacity of the system.

First, the control device maintains a constant level of the water level in the nose chamber 110 (S201 to S204).

That is, the control device checks whether the water level level in the rider chamber 110 (S201), and then checks whether the water level is less than the threshold value (S202). At this time, when the water level is less than the threshold value (S202), the control device opens the makeup valve 111 to supply salt water from the salt water chamber 132 to the brackish water chamber 110 (S203). And, if the water level level is higher than the threshold value (S202), the control device closes the makeup valve 111 to stop the salt water supply (S204).

Next, the control device checks the operating state of the membrane distiller 130 (S205 to S212).

That is, the control device checks the supply flow rate and the discharge flow rate of the membrane distiller 130 to calculate the flow rate ratio (S205, S206), and then checks whether the flow rate ratio is included within the allowable error range (±10%) (S207) ). At this time, the control device reports the abnormal operation of the membrane distiller 130 to the system administrator if the flow rate is not included within the allowable error range (S207) (S208). In addition, when the corresponding flow rate ratio is within the allowable error range (S207), the control device determines that the membrane distiller 130 operates normally, and then checks the water level level of the brine chamber 132 (S209).

Then, when the level of the water level in the brine chamber 132 is greater than or equal to a preset threshold (S210), the control device opens the discharge valve to discharge the brine to the outside (S211). In addition, when the water level level of the brine chamber 132 is less than a preset threshold value (S210), the control device closes the discharge valve to stop discharging the salt water (S212).

Next, the control device checks the operating state of the reverse electrodialysis machine 140 (S213 to S216).

That is, the control device checks the supply flow rate and the discharge flow rate of the membrane distiller 130 to calculate the flow rate ratio (S213, S214), and then checks whether the flow rate ratio is included within the allowable error range (±15%) (S215) ). At this time, the control device reports the abnormal operation of the reverse electrodialysis machine 140 to the system administrator if the flow rate is not included within the tolerance range (S215) (S216). In addition, when the corresponding flow rate ratio is within the allowable error range (S215), the control device determines that the membrane distiller 130 operates normally and then terminates the system control operation.

In this way, the hybrid power generation system 100 according to the embodiment of the present invention can not only prevent foreign substances that may cause fouling of the separation membrane from entering the system in advance, but also add additional Since the solvent used is unnecessary, it is also possible to reduce operating costs.

In addition, the hybrid power generation system 100 does not require the supply of additional solvents (brine, fresh water, brackish water) by fusion and integral use of individual processes, and since the system can be provided in the form of a package, there is no restriction on the location.

In addition, the hybrid power generation system 100 can control the composition and concentration of brine in a closed loop process. As described above, in the reverse electrodialysis process, the greater the difference in concentration between brine and fresh water, the greater the power production is possible. This can be confirmed through Experimental Example 1 and FIG. 3 .

In addition, the hybrid power generation system 100 can be applied by selecting an optimal combination that does not affect the durability of the separation membrane through a change of solvent or solute in the circulating loop process. For example, LiCl may be used instead of NaCl, and a solvent having a low boiling point such as methanol or ethanol may be used instead of water as a solvent.

In addition, the hybrid power generation system 100 integrates the existing individual processes, the membrane distillation process and the reverse electrodialysis process, and uses it as one, so that the chamber is configured in hardware in the connection between the two processes, and the control logic that the two processes are linked is reflected This is possible.

The method according to some embodiments may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Examples of the computer readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CDROMs and DVDs, magneto-optical disks such as floppy disks. hardware devices specially configured to store and execute program instructions, such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like.

Although the foregoing description has focused on novel features of the invention as applied to various embodiments, those skilled in the art will recognize the apparatus and method described above without departing from the scope of the invention. It will be understood that various deletions, substitutions, and changes are possible in the form and details of Accordingly, the scope of the invention is defined by the appended claims rather than by the description above. All modifications within the scope of equivalents of the claims are included in the scope of the present invention.

100 ; hybrid power generation system 110 ; nose chamber
111; makeup valve 112 ; first drain valve
113 ; nose level sensor 120 ; heat exchanger
130 ; membrane distiller 131 ; membrane vapor chamber
132; brine chamber 132a; second drain valve
132b; salt water level sensor 133 ; fresh water chamber
140 ; Counter-Mechanical Catapult 141 ; anode
141a; anode cell 142; cathode
142a; cathode cell A; anion exchange membrane
C; cation exchange membranes P1 to P3; 1st pump - 3rd pump
MD_in ; MD supply flow measuring sensor
MD_out1, MD_out2 ; MD discharge flow measurement sensor
RED_in1, RED_in2 ; RED supply flow measuring sensor
RED_out1 ; RED discharge flow measuring sensor

Claims (21)

a brackish chamber for storing and supplying brackish water;
a heat exchanger for heating and supplying the brackish water supplied from the brackish water chamber through heat exchange using the power generation waste heat;
a membrane distiller for separating and supplying brackish water heated by the heat exchanger into brine and fresh water through a membrane distillation process using brackish water heated by the heat exchanger; and
A reverse electrodialysis machine for generating electricity according to the difference in salinity by flowing brine and fresh water separated and supplied by the membrane distiller between the ion exchange membranes, but circulating brine and fresh water with different salinity concentrations to the brackish water chamber;
A hybrid power generation system using waste heat comprising a.
The method of claim 1,
The power generation waste heat,
A hybrid power generation system using waste heat, which is low-grade waste heat from fuel cell exhaust water.
The method of claim 1,
The membrane distiller,
A membrane distillation chamber comprising a hydrophobic polymer separation membrane to perform a membrane distillation process;
a brine chamber for storing high-concentration brackish water separated on one side of the membrane distillation chamber based on the hydrophobic polymer separation membrane; and
a freshwater chamber for storing a condensing unit separated on the other side of the membrane distillation chamber based on the hydrophobic polymer separation membrane;
A hybrid power generation system using waste heat comprising a.
4. The method of claim 3,
The reverse electrodialysis machine,
A plurality of cell regions are constituted by alternately arranging a cation exchange membrane and an anion exchange membrane between the anode and the cathode,
The plurality of cell regions,
an anode cell comprising an anode solution for supplying electrons through an oxidation reaction; and
a reduction electrode cell comprising a cathode solution receiving electrons through a reduction reaction;
A hybrid power generation system using waste heat comprising a.
5. The method of claim 4,
The anode solution and the cathode solution,
A hybrid power generation system using waste heat, which is a fixed type that does not circulate between the anode cell and the cathode cell, and includes a redox pair.
5. The method of claim 4,
a control device for determining the operating state of the membrane still and the reverse electrodialysis machine;
Hybrid power generation system using waste heat further comprising a.
7. The method of claim 6,
The control device is
A hybrid power generation system using waste heat to determine the operating state of the membrane distiller by calculating a flow rate ratio, which is a ratio of a supply flow rate and a discharge flow rate of the membrane distiller, and determining whether the flow rate ratio is within an allowable error range.
8. The method of claim 7,
The membrane distiller,
MD supply flow rate measuring sensor for measuring the total brackish water flow rate supplied from the heat exchanger; and
MD discharge flow rate measuring sensor for measuring the sum of the salt water flow rate and the fresh water flow rate discharged to the reverse electrodialysis machine;
The control device is
Measuring the supply flow rate of the membrane distiller through the MD supply flow measurement sensor,
A hybrid power generation system using waste heat to measure the discharge flow rate of the membrane still through the MD discharge flow measurement sensor.
7. The method of claim 6,
The control device is
A hybrid power generation system using waste heat to calculate the flow rate ratio, which is the ratio of the supply flow rate and the discharge flow rate of the reverse electrodialysis machine, and determine whether the flow rate ratio is within an allowable error range to determine the operating state of the reverse electrodialysis machine.
10. The method of claim 9,
The reverse electrodialysis machine,
a RED supply flow rate measuring sensor for measuring the combined flow rate of the brine flow rate and the fresh water flow rate supplied from the membrane distiller; and
Further comprising; a RED discharge flow rate measuring sensor for measuring the total flow rate of the rider discharged to the rider chamber;
The control device is
Measuring the supply flow rate of the reverse electrodialysis machine through the RED supply flow measurement sensor,
A hybrid power generation system using waste heat to measure the discharge flow rate of the reverse electrodialysis machine through the RED discharge flow rate measuring sensor.
7. The method of claim 6,
The control device is
A hybrid power generation system using waste heat to maintain a constant level of water levels in the brackish chamber and the brine chamber.
12. The method of claim 11,
The control device is
By confirming that the water level level in the brackish chamber is less than a predetermined threshold, a make-up valve between the brackish chamber and the brine chamber is opened to control supply of brine from the brine chamber to the brackish chamber. Hybrid power generation system using
12. The method of claim 11,
The control device is
The hybrid power generation system using waste heat to discharge the brine stored in the brine chamber to the outside by opening the discharge valve of the brine chamber by confirming whether the water level level of the brine chamber is equal to or greater than a predetermined threshold.
In the control method of a hybrid power generation system constituting a circulating closed loop of a nose chamber, a heat exchanger, a membrane distiller and a reverse electrodialysis machine,
determining an operating state of the membrane distiller or the reverse electrodialysis machine by using a flow rate ratio that is a ratio of a supply flow rate and a discharge flow rate of the membrane distiller or the reverse electrodialysis machine;
a reporting step of reporting the operating status of the hybrid power generation system according to determining the operating status of the membrane still or the reverse electrodialysis machine;
A control method of a hybrid power generation system using waste heat comprising a.
15. The method of claim 14,
The determining step is
calculating a flow rate ratio, which is a ratio of a supply flow rate and a discharge flow rate, by checking the supply flow rate and the discharge flow rate of the membrane distiller or the reverse electrodialysis machine; and
checking whether the flow rate ratio is within a preset tolerance range;
A control method of a hybrid power generation system using waste heat comprising a.
15. The method of claim 14,
Before determining the operating state of the film still, confirming whether the water level level of the nose chamber is less than a predetermined threshold value; and
supplying brine from the brine chamber included in the membrane still to the brine chamber when the water level level of the brine chamber is less than the threshold value;
A control method of a hybrid power generation system using waste heat further comprising a.
17. The method of claim 16,
after determining the operating state of the membrane still, confirming whether the water level level of the brine chamber is equal to or greater than a predetermined threshold value; and
discharging the brine from the brine chamber to the outside when the water level level of the brine chamber is greater than or equal to a threshold value;
A control method of a hybrid power generation system using waste heat further comprising a.
In the control device of the hybrid power generation system constituting the closed loop of the nose chamber, the heat exchanger, the membrane still and the reverse electrodialysis machine,
at least one processor; and
a memory for storing computer readable instructions;
The instructions, when executed by the at least one processor, cause the control device to:
to determine the operating state of the membrane distiller or the reverse electrodialysis machine by using a flow rate ratio that is a ratio of the supply flow rate and the discharge flow rate of the membrane distiller or the reverse electrodialysis machine;
The control device to report the operating status of the hybrid power generation system according to the determination of the operating status of the membrane still or the reverse electrodialysis machine.
19. The method of claim 18,
The instructions, when executed by the at least one processor, cause the control device to:
When determining the operating state of the membrane distillation machine or the reverse electrodialysis machine, the flow rate ratio, which is the ratio of the supply flow rate and the discharge flow rate, is calculated by checking the supply flow rate and the discharge flow rate of the membrane distillation machine or the reverse electrodialysis machine,
A control device to check whether the flow rate is within a preset tolerance range.
19. The method of claim 18,
The instructions, when executed by the at least one processor, cause the control device to:
Before judging the operating state of the membrane still, it is checked whether the water level of the nose chamber is less than a predetermined threshold,
If the water level level in the brackish chamber is less than the threshold, the control device to supply brine from the brine chamber included in the membrane still to the brackish chamber.
21. The method of claim 20,
The instructions, when executed by the at least one processor, cause the control device to:
After determining the operating state of the membrane still, it is checked whether the water level level of the brine chamber is equal to or greater than a predetermined threshold,
If the water level level of the brine chamber is greater than or equal to a threshold, the control device to discharge the brine from the brine chamber to the outside.

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