TW201512537A - Compressed air energy storage system - Google Patents

Abstract

A compressed air energy storage system is disclosure. The compressed air energy storage system comprises a low-pressure tank, a compressor, a high-pressure tank, and a turbine. The low-pressure tank and the high-pressure are filled first modified zeolites and second modified zeolites, respectively. Gas flows from the low-pressure tank to the high-pressure tank such as to chemical react and exchange thermal energy with the second modified zeolites, and then the gas flows from the high-pressure tank to the low-pressure tank such as to chemical react and exchange thermal energy with the first modified zeolites. During charging process, the high-pressure tank receives high-temperature and high-pressure gas compressed by the compressor to convert electronic energy to thermal energy and chemical energy for storing in the high-pressure tank, otherwise, to convert thermal energy and chemical energy stored in the high-pressure tank to electronic energy for outputting during discharging process.

Description

Compressed gas energy storage system

The present disclosure relates to an energy storage technology, and more particularly to a compressed gas energy storage system.

Large energy storage systems can be paired with intermittent power generation systems such as wind or solar power to store electricity during peak hours and release power during peak hours, thus helping to stabilize the grid and reduce power generation costs.

A large energy storage technology, such as the Compressed Air Energy Storage (CAES) system, which traditionally utilizes underground caverns to store compressed air, requires a considerable amount of space. When compressing and expanding air, there is a problem of compression temperature rise and expansion cooling. Therefore, in the process of compressing air, it is necessary to simultaneously cool the air. Conversely, the air must be reheated during the air expansion process (usually heated by natural gas or oil). Way), so a lot of heat will be lost to the formation. At present, many on-ground storage tank type compressed gas energy storage technologies have been developed, such as Pumped Heat Electricity Storage (PHES) technology, Isothermal Compressed Air Energy Storage (ICAES) technology, and adsorption. Adsorption-Enhanced Compressed Air Energy Storage (AE-CAES) technology.

The PHES system consists of two tanks filled with vermiculite and argon. The electric drive pump is used to compress the argon gas entering a tank to a temperature above 500 degrees Celsius. And heat transfer to the vermiculite, and further expand the argon gas into the other tank to reach minus 160 degrees Celsius and cool the vermiculite, so that there is a temperature difference between the two tanks, thereby converting electrical energy into heat energy storage, And when the electric energy demand is needed, the heat energy is converted into electric energy and released. The advantage of the PHES system is that it uses a high-capacity argon gas as the working fluid, but its operating temperature range is too large and the storage energy density is relatively low.

The AE-CAES system uses zeolite as a filling material and air as a working fluid. It uses a pressure swing method and a temperature swing method to achieve cyclic storage and release through four steps of constant temperature compression, constant pressure adsorption, constant pressure desorption and constant temperature expansion. The purpose of energy. However, in the AE-CAES technology, the amount of air adsorbed on the zeolite at low pressure is very rare. Therefore, the actual operation of the system is a constant pressure operation, and only the temperature swings, and the energy storage effect is not good.

The advantage of ICAES technology is that it uses sprinkling water to achieve constant temperature operation, and its theoretical thermal efficiency is high. However, its disadvantages are that it requires high pressure resistance of the storage tank and the control of the constant temperature operation is complicated.

Therefore, how to provide a high-energy storage, high-density, stable thermal energy, simple structure and small volume energy storage system technology is an urgent problem to be solved.

The present disclosure is a compressed gas energy storage system, comprising: a low pressure storage tank filled with a first modified zeolite; a high pressure storage tank filled with a second modified zeolite; a compressor connected to the low pressure storage tank and the high pressure storage tank a gas for compressing from the low pressure storage tank to the high pressure storage tank; and a turbine connecting the low pressure storage tank and the high pressure storage tank for expanding the gas flowing from the high pressure storage tank to the low pressure storage tank Wherein the gas is compressed from the low pressure storage tank through the compressor into the high pressure storage tank to chemically react with the second modified zeolite in the high pressure storage tank to be heated Exchanging, and the gas is expanded from the high pressure storage tank through the turbine into the low pressure storage tank to chemically react with the first modified zeolite in the low pressure storage tank for heat exchange.

In the charging state, the compressor receives a power supply to compress the gas flowing from the low pressure storage tank to the high pressure storage tank from a normal temperature and a normal pressure state to a high temperature and high pressure state, and the high temperature and high pressure gas enters the high pressure storage tank The second modified zeolite is exothermicly reacted with the second modified zeolite, thereby converting electrical energy into thermal energy and chemical energy stored in the high pressure storage tank. Then, the normal temperature and high pressure gas flowing out from the high pressure storage tank is expanded into a low temperature and normal pressure state through the turbine, and enters the low pressure storage tank to chemically react with the first modified zeolite to absorb heat from the first modified zeolite. The gas flowing out from the low pressure storage tank is at a normal temperature and a normal pressure state.

In the discharge state, the high-pressure storage tank stores a high-temperature and high-pressure gas flowing from the high-pressure storage tank to the turbine to drive the turbine to generate electricity, thereby storing the heat energy stored in the high-pressure storage tank. Converted from chemical energy to electrical energy output. Then, the high-temperature and high-pressure gas flowing out from the high-pressure storage tank is expanded into a normal temperature and normal pressure state through the turbine, and enters the low-pressure storage tank to chemically react with the first modified zeolite to exotherm the first modified zeolite. The gas flowing out of the low pressure storage tank is in a low temperature and normal pressure state. Then, the low-temperature and normal-pressure gas is compressed into a normal temperature and high pressure state by the compressor, and enters the high-pressure storage tank to chemically react with the second modified zeolite to absorb heat from the second modified zeolite, so that the high-pressure storage is performed. The gas in the tank is in a high temperature and high pressure state.

In one embodiment, the gas used in the compressed gas energy storage system is carbon dioxide, and the first or second modified zeolite used is a modified zeolite containing magnesium ions.

Compared with the prior art, the present disclosure is based on the principle that the chemical reaction heat is higher than the sensible heat. The reaction of carbon dioxide with modified zeolite containing magnesium ions can release/absorb a large amount of heat, greatly increasing the storage density of the system, and the working temperature range is relatively small, and the volume occupied is relatively reduced.

1, 1a‧‧‧ low pressure storage tank

11, 11a‧‧‧ first modified zeolite

2‧‧‧Compressor

3, 3a‧‧‧ high pressure storage tank

31, 31a‧‧‧Second modified zeolite

4‧‧‧ turbine

5‧‧‧Connected fittings

E ₁ , E ₂ , E ₃ , E ₄ ‧‧‧ Electricity

1 is a view showing the basic components of the compressed gas energy storage system of the present disclosure and a charging diagram thereof; FIG. 2 is a view showing the basic components of the compressed gas energy storage system of the present disclosure and a discharge diagram thereof; and FIG. 3 is a view showing the compressed gas of the present disclosure. Experimental results of adsorption capacity of modified zeolite containing magnesium ions in an energy storage system.

Other embodiments of the present disclosure will be readily understood by those skilled in the art from this disclosure.

1 and 2 are schematic views respectively showing charging and discharging of the compressed gas energy storage system of the present disclosure. As shown in Fig. 1, the compressed gas energy storage system of the present disclosure includes a low pressure storage tank 1, a compressor 2, a high pressure storage tank 3, a turbine 4, and a connecting pipe member 5 connecting the aforementioned members.

The low pressure storage tank 1 and the high pressure storage tank 3 are filled with the first modified zeolite 11 and the second modified zeolite 31, respectively. In the present embodiment, the first modified zeolite 11 and the second modified zeolite 31 used are all modified zeolites containing magnesium ions (for example, Mg-13X), which can be replaced by magnesium ion exchange using the principle of anion-cation exchange. The original cation on the zeolite. Experimental data shows that the content of magnesium ions in the zeolite ranges from 3 to 10% by weight, which can increase the storage density of the compressed gas energy storage system disclosed herein.

The compressor 2 is connected to the low pressure storage tank 1 and the high pressure storage tank 3 for compressing the gas flowing from the low pressure storage tank 1 through the connecting pipe 5 to the high pressure storage tank 3, and the gas is heated by the compressor 2 to increase its temperature and pressure. . The turbine 4 is connected to the low pressure storage tank 1 and the high pressure storage tank 3 for expanding the gas flowing from the low pressure storage tank 1 through the connecting pipe 5 to the high pressure storage tank 3, and the gas is lowered by the turbine 4 to lower its temperature and pressure.

During charging or discharging, the gas is compressed from the low pressure storage tank 1 via the compressor 2 and passed through the connecting pipe 5 into the high pressure storage tank 3 to be chemically reacted with the second modified zeolite 31 in the high pressure storage tank 3 to be heated. In exchange, in addition, the gas is expanded from the high pressure storage tank 3 via the turbine 4 and passed through the connecting pipe 5 into the low pressure storage tank 1 to be chemically reacted with the first modified zeolite 11 in the low pressure storage tank 1 for heat exchange.

In the state of charge, as shown in Fig. 1, the first modified zeolite 11 in the low pressure storage tank 1 contains magnesium oxide (MgO), and the second modified zeolite 31 in the high pressure storage tank 3 is reacted by high pressure MgO. Magnesium carbonate (MgCO ₃ ). In the discharge state, as shown in Fig. 2, the first modified zeolite 11a in the low pressure storage tank 1a contains magnesium carbonate, and the second modified zeolite 31a in the high pressure storage tank 3a contains magnesium oxide. Further, in the present embodiment, the gas used is carbon dioxide. The chemical reaction and heat exchange in the low pressure storage tank and the high pressure storage tank during the charging process and the discharging process are described in detail below.

Referring to Figure 1, when the state of charge, there is provided a power E ₁ to the compressor 2, the compressor 2 is driven to compress the carbon dioxide, so that through the connecting tube 5 into the carbon dioxide compressor of high temperature and pressure state 2, the state of high temperature and pressure The carbon dioxide enters the high pressure storage tank 3 to carry out the following chemical reaction with the second modified zeolite 31 therein: MgCO ₃ → MgO + CO ₂ ΔH > 0 (1)

It is known from the chemical formula (1) that the second modified zeolite 31 (containing MgCO ₃ ) in the high pressure storage tank 3 absorbs heat of carbon dioxide from the high temperature and high pressure state, thereby converting electric energy (ie, electric power E ₁ ) into heat energy and The chemical energy is stored in the high pressure storage tank 3.

Then, the carbon dioxide in the normal temperature and high pressure state flows out from the high pressure storage tank 3, and the carbon dioxide in the normal temperature and high pressure state is expanded into the low temperature and normal pressure state by the turbine 4, wherein the turbine 4 outputs a small amount of electric power E ₂ during the process of expanding the carbon dioxide. E ₁ is very small compared to when too much off-peak period, which provides power to the compressor 2 E _1, E ₁ can use this power is converted into heat and the chemical energy stored in the high pressure storage tank 3. Therefore, it does not affect the charging performance of the overall system. Then, the low-temperature and normal-pressure carbon dioxide enters the low-pressure storage tank 1 through the connecting pipe member 5 to perform the following chemical reaction with the first modified zeolite 11 therein: MgO+CO ₂ → MgCO ₃ ΔH<0 (2)

It is known from the chemical formula (2) that the low-pressure normal temperature carbon dioxide flowing into the low-pressure storage tank 1 absorbs heat from the first modified zeolite (containing MgO) to generate MgCO ₃ , so that the carbon dioxide flowing out of the low-pressure storage tank 1 is normal temperature and pressure. State, to be re-entered into the compressor 2.

Therefore, carbon dioxide is repeatedly circulated through the connecting pipe member 5 between the low pressure storage tank 1, the compressor 2, the high pressure storage tank 3, and the turbine 4, and the first modified zeolite 11 (containing MgO) repeatedly adsorbs carbon dioxide and the second modified zeolite 31 ( The MgCO ₃ -containing compound is repeatedly desorbed with carbon dioxide, thereby converting electric energy into thermal energy and chemical energy and stored in the high-pressure storage tank 3. Therefore, the chemical formulas (1) and (2) using carbon dioxide and modified zeolite containing magnesium ions can greatly increase the heat absorbed by the high-pressure storage tank 3 and the low-pressure storage tank under a limited volume, working temperature and working pressure. The heat that can be released, thereby increasing the energy storage density.

Referring to Fig. 2, the second modified zeolite 31a in the high pressure storage tank 3a contains the magnesium oxide (MgO) after the endothermic desorption of carbon dioxide by the magnesium carbonate (MgCO ₃ ), and the first modified zeolite 11a in the low pressure storage tank 1a contains The aforementioned magnesium carbonate after exothermic adsorption of carbon dioxide. In the discharge state, the high-temperature and high-pressure carbon dioxide stored in the high-pressure storage tank 3a flows out to the turbine 4 through a control valve (not shown) to drive the turbine 4 to generate and output electric power E ₃ , thereby storing the high-pressure storage tank 3a. The thermal energy is converted to electrical energy (ie, electrical E ₃ ) output.

Then, the high-temperature and high-pressure carbon dioxide is expanded by the turbine 4 to a normal temperature and normal pressure, and the normal-temperature and normal-pressure carbon dioxide enters the low-pressure storage tank 1a through the connecting pipe member 5 to perform the chemical formula (1) with the first modified zeolite 11a, and the first modification is performed. The endothermic state of the zeolite 11a causes the carbon dioxide to change from a normal temperature to a normal state. Then, the low-temperature normal-pressure carbon dioxide flows out from the low-pressure storage tank 1a, and the low-temperature normal-pressure carbon dioxide is compressed by the compressor 2 into a normal-temperature high-pressure state, wherein the electric power E ₄ required to drive the compressor 2 is compared with the turbine 4 The generated electric power E _{3 is} relatively small, and when power is absent during the peak period, power E ₄ is supplied to the compressor 2, whereby the thermal energy and chemical energy stored in the high-pressure storage tank 3a can be converted into electric energy via the turbine 4 (ie, electric power E). ₃ ) Output.

Therefore, it will not affect the power generation efficiency of the overall system. Then, the carbon dioxide in the normal temperature and high pressure state enters the high pressure storage tank 3a through the connecting pipe member 5 to carry out the chemical formula (2) with the second modified zeolite 31a, and the second modified zeolite 31a adsorbs carbon dioxide to release heat, so that the heat is stored in the high pressure storage tank 3a. Carbon dioxide is in a high temperature and high pressure state for later discharge.

Therefore, carbon dioxide is repeatedly circulated through the connecting pipe member 5 between the low pressure storage tank 1a, the compressor 2, the high pressure storage tank 3a, and the turbine 4, and the second modified zeolite 31a (including MgO) repeatedly adsorbs carbon dioxide and the first modified zeolite 11a ( The MgCO ₃ is repeatedly desorbed with carbon dioxide, whereby the thermal energy and chemical energy stored in the high pressure storage tank 3a are converted into electric energy and output.

Furthermore, refer to Tables 1 and 2 below, which is an experimental example of the present disclosure. It can be seen from Tables 1 and 2 that in the experiment with an adsorption heat of 118 kJ/mol, the energy storage density of the present disclosure is 28.4 kWh/m ³ , which is higher than that of the PHES technology and the AE-CAES technology. Although the energy storage density of ICASE technology is low, the working pressure required by ICAES technology is too large, resulting in increased equipment cost and technical complexity.

In addition, it should be noted that the low temperature referred to herein is about -75 ° C, the normal temperature is about 25 ° C, the high temperature is about 300 ° C, the normal pressure is about 1 bar, the high pressure is about 12 bar, and the values are in the technical field. Usually understood by the knowledge person, not to limit this Revealed.

Furthermore, the modified zeolite containing magnesium ions filled in the low pressure storage tank 1 (1a) and the high pressure storage tank 3 (3a) need not be intentionally distinguished as MgO and MgCO ₃ because the carbon dioxide is connected to the low pressure storage tank by the connecting pipe 5. 1 (1a), the compressor 2, the high pressure storage tank 3 (3a) and the turbine 4 are continuously circulated, and the chemical formulas (1) and (2) are also in the low pressure storage tank 1 (1a) and the high pressure storage tank 3 (3a). Repeatedly, therefore, the first modified zeolite is also converted between MgCO ₃ and MgO, and the second modified zeolite is also converted between MgO and MgCO ₃ .

Further, referring to Fig. 3, which is the amount of carbon dioxide adsorbed by the modified zeolite containing Mg ions (including MgO), it can be seen from Fig. 3 that the amount of carbon dioxide adsorbed is almost unchanged after a plurality of cycles.

In summary, the disclosure discloses that the chemical reaction heat is higher than the sensible heat, and the modified zeolite containing magnesium ions (including MgO or MgCO ₃ ) and carbon dioxide (CO ₂ ) are used as a medium to form a reaction between MgO and CO _{2 .} The large amount of thermal energy is released during the MgO ₃ process, which effectively increases the energy storage density of the system, and the adsorption capacity of the magnesium ion zeolite for carbon dioxide is almost unchanged after multiple cycles, and the stability of the system energy storage is maintained larger.

The above embodiments are merely illustrative of the effects of the present disclosure, and are not intended to limit the disclosure, and those skilled in the art can implement the above embodiments without departing from the spirit and scope of the disclosure. Make modifications and changes. In addition, the number of components in the above-described embodiments is merely illustrative and is not intended to limit the disclosure. Therefore, the scope of protection of the present disclosure should be as set forth in the scope of the patent application described later.

1‧‧‧Low pressure storage tank

11‧‧‧First modified zeolite

2‧‧‧Compressor

3‧‧‧High pressure storage tank

31‧‧‧Second modified zeolite

4‧‧‧ turbine

5‧‧‧Connected fittings

E ₁ , E ₂ ‧‧‧ Electricity

Claims (10)

A compressed gas energy storage system comprising: a low pressure storage tank filled with a first modified zeolite; a high pressure storage tank filled with a second modified zeolite; a compressor connected to the low pressure storage tank and the high pressure storage tank, a gas compressed from the low pressure storage tank to the high pressure storage tank; and a turbine coupled to the low pressure storage tank and the high pressure storage tank for expanding the gas flowing from the high pressure storage tank to the low pressure storage tank, wherein Gas is compressed from the low pressure storage tank through the compressor into the high pressure storage tank to be chemically reacted with the second modified zeolite in the high pressure storage tank for heat exchange, and the gas is expanded from the high pressure storage tank through the turbine The low pressure storage tank is heat exchanged by chemical reaction with the first modified zeolite in the low pressure storage tank. The compressed gas energy storage system of claim 1, wherein the gas is carbon dioxide, and the first modified zeolite and the second modified zeolite are both modified zeolites containing magnesium ions. The compressed gas energy storage system of claim 2, wherein the first modified zeolite or the second modified zeolite contains magnesium ions in an amount ranging from 3 to 10% by weight. The compressed gas energy storage system of claim 1, wherein in the charging state, the compressor receives a power supply to flow the gas from the low pressure storage tank to the high pressure storage tank from normal temperature and pressure. The state is compressed into a high temperature and high pressure state, and the high temperature and high pressure gas enters the high pressure storage tank to chemically react with the second modified zeolite to exotherm the second modified zeolite, and convert the electric energy into heat energy and The learning can be stored in the high pressure storage tank. The compressed gas energy storage system of claim 4, wherein the normal temperature and high pressure gas flowing out of the high pressure storage tank is expanded into a low temperature and normal pressure state by the turbine, and enters the low pressure storage tank to A modified zeolite is subjected to a chemical reaction to absorb heat from the first modified zeolite, so that the gas flowing out of the low pressure storage tank is at a normal temperature and a normal pressure state. The compressed gas energy storage system of claim 5, wherein, in the charged state, the first modified zeolite contains magnesium oxide and reacts with a gas entering the low pressure storage tank to produce magnesium carbonate, and the first The second modified zeolite contains magnesium carbonate and reacts with a gas entering the high pressure storage tank to produce magnesium oxide. The compressed gas energy storage system of claim 1, wherein in the discharge state, the high pressure storage tank stores a gas in a high temperature and high pressure state, and the high temperature and high pressure gas flows out from the high pressure storage tank to the The turbine drives the turbine to generate electricity, and converts the thermal energy and chemical energy stored in the high pressure storage tank into electrical energy output. The compressed gas energy storage system of claim 7, wherein the high temperature and high pressure gas flowing out of the high pressure storage tank is expanded into a normal temperature and normal pressure state by the turbine, and enters the low pressure storage tank and the first The modified zeolite undergoes a chemical reaction to exotherm the first modified zeolite, so that the gas flowing out of the low pressure storage tank is in a low temperature and normal pressure state. The compressed gas energy storage system of claim 8, wherein the low-temperature and normal-pressure gas is compressed into a normal temperature and high pressure state by the compressor, and enters the high-pressure storage tank to perform chemistry with the second modified zeolite. The reaction absorbs heat from the second modified zeolite, so that the gas in the high pressure storage tank is in a high temperature and high pressure state. The compressed gas energy storage system of claim 9, wherein, in the discharged state, the first modified zeolite contains magnesium carbonate and reacts with a gas entering the low pressure storage tank to produce magnesium oxide, and the first The second modified zeolite contains magnesium oxide and reacts with a gas entering the high pressure storage tank to produce magnesium carbonate.