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    • 专利摘要:
    Thermochemical-mechanical energy storage facility and energy storage procedure. The energy storage facility comprises an endothermic block with an endothermic reactor (1) configured to receive a stream of methanol and heat at medium/low temperature (2) and produce a synthesis gas (3) by thermal decomposition of methanol. It also comprises an exothermic block with an exothermic reactor (5) configured to receive a synthesis gas stream from the endothermic block and produce a methane-rich gas stream (6), at high pressure and high temperature, by methanation; and a heat engine (7) configured to receive the current rich in methane (6) and generate mechanical energy. The energy storage procedure is carried out in said facility. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2792748A1
    申请号:ES201930406
    申请日:2019-05-08
    公开日:2020-11-11
    发明作者:Ramírez Ricardo Chacartegui；Villanueva José Antonio Becerra；Millán José Manuel Valverde；Domínguez Carlos Ortiz；Giuseppe Masci
    申请人:Universidad de Sevilla；
    IPC主号:
    专利说明:

    [0002] OBJECT OF THE INVENTION
    [0004] The invention belongs to the energy sector and specifically to the energy storage sector. It is also used for the generation of fuels with a high concentration of methane such as natural gas or the like.
    [0006] BACKGROUND OF THE INVENTION
    [0008] Energy storage is a highly developed research area both for better integration into the grid of renewable energy sources and for optimized management of energy resources.
    [0010] The most industrially developed thermal energy storage systems are sensible heat storage systems. These use as storage medium water, molten salts, mineral oils or other materials with high heat capacity in which heat is stored due only to its variation in temperature.
    [0012] Other widely studied thermal energy storage systems are those based on materials that undergo a phase change when heated (latent heat).
    [0014] An alternative to sensible or latent heat storage is the use of reversible chemical reactions, currently under investigation. In general, thermochemical energy storage facilities (TCES) are characterized by the use of two reactors: a reactor where the endothermic reaction takes place using the heat supplied by an external source (charging phase); and an exothermic reactor, in which the reverse reaction releases previously stored heat (discharge phase). The heat released during the discharge phase is used according to the temperature and power released (for example for electricity production, domestic heating, industrial processes, etc.).
    [0015] One of the main advantages of TCES systems is that, depending on the reversible reaction involved, high energy densities can be achieved compared to sensible or latent heat storage. Furthermore, if the reagents are stable, they can be stored for long periods of time, allowing long-term storage, even seasonal if the products can be stored at room temperature.
    [0017] A currently known type of thermochemical energy storage is based on the thermal decomposition of methanol.
    [0019] Methanol is produced at an industrial level generally by means of synthesis gas obtained from reforming natural gas with steam, although it is also possible to produce synthesis gas by: i) gasification of coal or biomass; ii) from biomethane; iii) through a CO2 capture and reuse process; iv) by means of “black liquor ” wood waste and v) by means of conversion of excess renewable electricity into liquid fuel. In these processes a series of thermochemical processes take place, including pyrolysis, gasification and liquefaction, depending on the types of products sought .
    [0021] In this sense, the possibility of producing methanol from biomass, through the use of solar energy, has already been studied. The reversible reaction involved in the decomposition of methanol into hydrogen and carbon monoxide is given by the following expression:
    [0023] CH3OH AHr ^ 2H2 CO
    [0025] The enthalpy of reaction under standard conditions is AH ° = 90.7 kJ / mol. Additionally, the thermal decomposition of methanol can involve other side reactions that lead to the formation of by-products such as dimethyl ether and methane.
    [0027] The use of the methanol decomposition reaction as an energy storage system has the following advantages:
    [0028] • Methanol is in a liquid state under ambient conditions. Its boiling temperature at atmospheric pressure is approximately 65 ° C. This allows storage in reduced volumes and facilitates its handling and transport.
    [0030] • The reaction occurs at moderate temperatures, depending on the catalyst used. Complete methanol conversion can be obtained at temperatures around 315 ° C. This is a relatively low reaction temperature compared to that required in other TCES applications and is therefore of interest in medium / low temperature energy storage applications.
    [0032] • Methanol can be produced from biomass through pyrolysis or gasification processes.
    [0034] Thus, the thermal decomposition of methanol is of interest integrated with medium / low temperature applications such as parabolic trough technology solar plants. The use of solar energy to carry out the decomposition reaction of methanol has already been studied in the state of the art, presenting good results in terms of performance. The system works with an inlet stream of methanol that decomposes inside the solar reactor at a temperature of around 300 ° C, with a methanol conversion rate of around 90% and using CuO / ZnO / AL2O3 as a catalyst. The reaction results in synthesis gas (hydrogen and carbon monoxide), which is sent to a power unit where it is used as fuel.
    [0036] Once the synthesis gas has been produced and stored, it can be used directly as fuel in an open process, or the reverse reaction of methanol synthesis can be carried out in a closed process. The temperature at which the methanol decomposition reaction occurs with appreciable conversion is around 250 ° C. The reverse reaction takes place with a high conversion at a relatively high pressure (50 bar). Due to the moderate temperature and high pressures required in the exothermic reaction, the use of a direct closed cycle would present low performance and technological challenges for its industrial application.
    [0038] On the other hand, the reaction between the products of the methanol decomposition process can lead to the formation of methane and water, known as the methanation reaction. Methane results in a gas (methane) at high temperature and pressure that can be expanded in a turbine for efficient electricity production. The methane obtained can be burned for conventional electricity production or for use in thermal processes.
    [0040] The methanation reaction is:
    [0041] 3H2 CO CH4 H2O AHr
    [0043] The enthalpy of reaction under standard conditions is AH ° = -206 kJ / mol. The degree of conversion of CO is close to one at 30 bar and 600 ° C depending on the catalyst used. At atmospheric pressure, the conversion of CO is total around 400 ° C.
    [0045] There are different proposals for energy storage systems based on the use of methanol. For example, a thermal energy storage system has been proposed using the decomposition and synthesis of methanol. In this system the synthesis of methanol takes place in two stages, with methyl formate as an intermediate.
    [0047] The use of solar energy for the decomposition of methanol has already been described in the state of the art through its integration with a power cycle without a storage system. Likewise, document DE102012214907 describes a system comprising an electrolysis unit of a steam plant to provide hydrogen and oxygen and a methanation reactor using carbon dioxide. The electrolysis unit generates hydrogen and oxygen while the methanation unit is configured to synthesize methane and / or methanol.
    [0049] A system that produces a stream of methane and hydrogen has also been proposed. In this system a stream containing alkanes mixes with steam and carbon dioxide. The reactions on which this system is based do not allow energy to be stored and the objective is to produce a methane-hydrogen mixture at low cost.
    [0051] A methanol production method is also known, described in US5767165 based on the thermal decomposition of methane and the subsequent reaction of the hydrogen obtained with CO2.
    [0052] A thermal decomposition process of methanol in the range 250 ° C-500 ° C has also been described, and studies have been carried out based on the process to control the H2 / CO ratio produced.
    [0054] In the state of the art it has also been described, in document GB798741, a reactor that uses methanol as the main source to produce a gas containing hydrogen,
    [0055] carbon monoxide and methane. The heat released by exothermic reactions is used to drive the endothermic process. That is, a chemical conversion of the fuel is described that does not allow the storage of energy.
    [0057] DESCRIPTION OF THE INVENTION
    [0059] The present invention proposes a thermochemical-mechanical energy storage installation and an energy storage method in said installation.
    [0061] The key to the invention is that it combines the processes of thermal decomposition of methanol, through the contribution of heat at medium / low temperature (preferably below 350 ° C), compression of the gases produced from the decomposition of methanol (this concludes what called the loading phase), and the process of methanation of the synthesis gas that releases a stream rich in methane.
    [0063] A stream rich in methane is obtained at high pressure (preferably between 25 and 70 bar) and temperature (preferably above 500 ° C) which is subsequently expanded in a turbine to recover part of the energy that has been used in the compression process during the loading phase for storage (called the unloading phase). Likewise, the proposed installation includes a storage unit for the synthesis gas produced.
    [0065] The installation comprises an endothermic block where a stage called the loading phase is carried out, which allows the storage of energy in two different ways, chemical and mechanical. On the one hand, the heat contributed by breaking the chemical bonds of methanol is stored (this occurs in an endothermic reactor). On the other hand, mechanical energy is stored by compressing the synthesis gases produced in said reaction (energy supplied by a compressor).
    [0066] Likewise, the installation comprises an exothermic block where a stage that has been called the discharge phase is carried out, which consists of the methanation of the synthesis gas (which has been previously generated in the endothermic block). In it a gas is obtained at high temperature (higher than 600 ° C) and with a high concentration of methane (if the complete conversion of hydrogen is carried out, in an embodiment of the invention, a stream with a composition of 66 , 7 mole% in methane gas). Such a stream with a high concentration of methane can be used in conventional combustion systems (for example in industrial process boilers).
    [0068] The endothermic block and the exothermic block can work simultaneously or at different times. Furthermore, each block is equipped with heat exchangers that allow optimizing the overall thermal recovery of the system. These exchangers can be independent from the thermal point of view for each block, or they can be coupled between the blocks (that is, heat exchangers can be arranged that transfer heat from the endothermic to the exothermic side or vice versa).
    [0070] The proposed installation features remarkable storage performance and flexibility of integration with other technologies. It can also be coupled to other facilities in which industrial processes that require heat flows are carried out or be coupled to energy production systems at high temperatures.
    [0072] It also allows the use of surplus energy that may exist in the electrical network due to a supply peak from renewable energy sources (for example, wind energy during night hours). In addition, the installation makes it possible to cope with electricity demand peaks during the day.
    [0074] The endothermic block reactor is fed by a stream of methanol and the heat source used for the reaction is a medium / low temperature source. Said heat source can be a solar source (medium / low temperature). The endothermic reactor can be integrated with the solar concentrators (the methanol reacts in the solar concentrator itself, that is, the concentrator itself is the endothermic reactor when the installation has a system that includes solar concentrators) or it can be external (a heat transfer fluid that carries the heat from the solar concentrators or from any other thermal source to the endothermic reactor).
    [0076] Subsequently, the installation makes it possible to provide high temperature heat during the discharge phase (it releases a stream rich in methane at high pressure and high temperature). The relatively low temperatures required for the endothermic decomposition reaction of methanol, around 300 ° C, make the installation suitable for application in a wide variety of geographical areas, even with moderate availability of solar resources, as well as in processes industrial plants where there are residual heat currents at a sufficiently high temperature.
    [0078] The installation can be used as a thermal storage system, by breaking and forming chemical bonds, in any application with heat at medium / low temperature (in a range around 300 ° C) to carry out the methanol decomposition reaction . This heat input can be made by means of medium / low temperature solar systems or by residual heat from other processes. Furthermore, the streams rich in combustible components, obtained through the methanation reaction, mainly methane and carbon monoxide, can be used as fuel for the generation of thermal energy and / or power production not mentioned in the present description.
    [0080] The thermochemical storage of the heat supplied to the endothermic reactor by means of the medium / low temperature heat source is carried out in the endothermic block, which combines the thermal decomposition of methanol in an endothermic reactor to generate synthesis gas which is compressed for its storage. Syngas can be stored for long periods if the operation of the endothermic and exothermic blocks of the facility is decoupled. Said synthesis gas mainly comprises hydrogen and carbon monoxide.
    [0082] The discharge phase is carried out in the exothermic block. The methanation reaction is carried out in which the synthesis gas stored at high pressure is sent to an exothermic reactor where, from the compressed synthesis gas, a gas stream with a high content of methane is obtained. The gas produced from methanation is sent to a turbine (or any other motor heat engine) that is also part of the exothermic block and that allows generating mechanical energy (or electrical in the case of being coupled to an electrical generator).
    [0084] The mechanical energy required to compress the syngas for storage can be electrical or mechanical (for example, driven by heat engines operated with methane or other fuels). The synthesis gas compression process can be carried out in a single stage or in several stages with intermediate cooling. By passing the synthesis gas through intermediate heat recovery units, the energy consumption for compression is reduced. Before being stored, the synthesis gas is preferably cooled in a separator, which is part of the endothermic block, until it reaches a temperature close to room temperature. This cooling carried out in the separator allows the unreacted methanol to be separated by means of a condensation process since the synthesis gas does not condense and can flow from the top of the separator. The liquid methanol is recirculated to mix with the methanol entering the endothermic reactor and the synthesis gas is sent to the storage tank.
    [0086] The exothermic block or discharge phase comprises an exothermic reactor in which the methanation reaction is carried out. The synthesis gas enters said exothermic reactor, which was stored under pressure in the storage tank of the endothermic block. Said gas is previously heated using available heat from the gas streams coming out of the turbine (motor heat engine or heat engine) or any other stream at available temperature from the integration of processes.
    [0088] In the discharge phase, energy recovery is carried out by expanding the stream rich in methane to produce mechanical energy in the turbine or by using the methane produced by burning it in a power plant, in thermal processes or in chemical processes.
    [0090] In the exothermic reactor, the methanation reaction takes place, which is carried out with an excess of carbon monoxide. At the exit of the exothermic reactor, there is a stream of gas rich in methane at a temperature that is preferably higher than 600 ° C (that is, it is a higher temperature than that of the original heat source used in the decomposition of methanol. which is preferably found around 300 ° C). These temperatures are preferably reached when the reactor operates at pressures of 30 bar or higher.
    [0092] Thanks to the fact that the installation includes the exothermic reactor in which the methanation takes place, it allows optimizing the use of the chemical energy contained in the synthesis gas obtained as a product of the processes carried out in the endothermic block. The conversion to methane depends on the operating conditions (methanation temperature and pressure), the composition of the inlet gas (injection of other gases) and the catalyst used. The power released in the reaction is controlled by adjusting the mass flow rate of the syngas released from the storage tank. The temperature of the reaction is controlled by adjusting the mass flow rate and the methanation pressure. Optimal configuration parameters vary depending on the purpose of the application and the power level required.
    [0094] In an exemplary embodiment, other gases can be injected into the exothermic reactor to act in the methanation reaction (for example inert gases, carbon dioxide, carbon monoxide, hydrogen). These gases can be used internally in the exothermic reactor to utilize the heat released by the methanation reaction. Depending on the objective of the installation, an optimal value can be selected to make the installation more energy efficient or to reduce the volume of syngas storage.
    [0096] The high methane gas stream can be used directly in combustion applications such as thermal and electrical generation or combinations of both. It can also be used directly in existing applications that are designed to operate with natural gas (such as gas turbines, combined cycles or boilers). In other cases, the high-methane gas stream can be used to produce electrical energy by direct expansion. In these cases, the installation comprises a turbine mounted downstream of the exothermic reactor. Methane formed in the exothermic reactor and unreacted carbon monoxide can be fed into the turbine. In this case, a part of the electrical energy used for the compression of the synthesis gas prior to its storage in the loading phase (in the endothermic block) can be recovered.
    [0097] Furthermore, in an exemplary embodiment, the synthesis gas that is withdrawn from the storage tank to be sent to the exothermic reactor can be passed through a second separator. In it, the water is cooled to room temperature to separate it, by condensation, from the rest of the gas. In this way, a stream rich in methane is obtained that can be sent directly for use as fuel in a boiler or power production system.
    [0099] In an exemplary embodiment, the installation is coupled to a power production system, such as a combined cycle, so that the gases produced in methanation are burned in an additional combustion chamber and the heat produced in the reaction is used as additional heat for the power cycle (it can be used for example to superheat steam or in excess evaporation in a steam cycle) or to preheat the compressor outlet air prior to its entry into the combustion chamber in a cycle of a gas turbine ..
    [0101] In another embodiment, the heat released in the exothermic reactor is used internally in the installation, for example, by increasing the mass flow rate of the inlet stream to the exothermic reactor (in this way it is achieved that the reactor operates in a regime close to an adiabatic reactor and the absorption of the heat generated by the reactions that take place inside it is favored).
    [0103] In one embodiment of the invention, the installation comprises an electrolyzer for producing hydrogen which is used in the exothermic reactor to achieve or approach a stoichiometric methane reaction. This variant provides a greater amount of heat in the methanation process and produces a stream with a very high concentration of methane (there may be a small amount of CO depending on the reaction conditions). On the other hand, the electrical consumption of the system increases.
    [0105] In another possible embodiment, the endothermic reactor works at high pressure. In this case, the increase in pressure penalizes the endothermic reaction, thus requiring a higher temperature or less conversion of methanol is obtained. However, the work required in the synthesis gas compression process is reduced. In this variant, the installation may require higher temperature heat sources. In the case of solar energy, depending on the temperature level, the installation can comprise concentration systems of tower technology and parabolic trough technology.
    [0106] Another object of the present invention is a thermochemical-mechanical energy storage method in the installation of the present invention.
    [0108] The generation and storage procedure begins in the endothermic reactor where the decomposition of methanol into synthesis gas occurs. The process continues in a heat recovery unit and then the synthesis gas is compressed in a compressor (alternatively in a compressor train with intermediate cooling). The heat contained in the compressor exhaust gas is recovered in a heat recovery unit before entering the separator. In the separator, the amount of methanol that has not reacted in the endothermic reactor is separated from the synthesis gas, obtaining this in liquid form. The methanol is recirculated and is incorporated into the incoming methanol flow, heating through said recuperators. The synthesis gas is sent to the storage tank, thus completing the charging phase of the system.
    [0110] The discharge phase begins with the exit of the syngas from the storage tank. Said gas is heated through a heat recovery unit and reacts in the exothermic reactor where the methanation reaction takes place. In this reaction, heat is produced at a temperature around 600 ° C or higher that can be used to generate electrical energy in an external power cycle. The gas produced in methanation is sent to a turbine or thermal motor engine and its expansion generates mechanical energy that is convertible to electrical energy. Said gas is sent to the heat recovery unit and subsequently to a separator where the water produced in the methanation reaction is separated and can be sent to a power cycle, a thermal generation system or a chemical process.
    [0112] The procedure starts from a methanol source. Said source of methanol can be of multiple origin and can be renewable in case it comes from biomass and / or organic waste. In other cases, methanol can come from different gasification processes, combined with carbon dioxide capture processes, hydrogenation processes, or any other.
    [0114] The present invention is an integrated installation (combines loading and unloading phases) that presents a synergistic behavior from which the following advantages are derived, among others:
    [0115] • Provides applicable energy storage for any thermal input power, whether for microgeneration or industrial scale.
    [0117] • It allows a long storage time without thermal losses.
    [0119] • It is a tri-generation system, capable of producing gas with a high content of methane, thermal energy at high temperature and electrical energy with high yields. The electrical recovery is approximately 75% and the net high temperature heat flux generated at discharge time is greater than that of low temperature input. It has the ability to generate energy in the form of electricity, heat or through the production of a fuel, allowing great flexibility to meet the user's need.
    [0121] • The heat supplied takes place at medium-low temperatures, around 300 ° C and lower, which can be reached by current solar concentration systems, and the heat release process allows temperatures of up to 600 ° C depending on the conditions of operation in the methanation reactor. The released heat can be used to increase electrical energy production or for any other use in industrial processes.
    [0123] • Integration with a power production system, allows to store thermal energy with high performance. In this sense, it works like a battery, for which the energy to drive the compressors, of electrical or mechanical origin, stored during the charging phase (for example from photovoltaic energy) can be injected into the electrical network at the appropriate time of the day to meet peak demand.
    [0125] • The system produces a gas with a lower calorific value (PCI) higher than liquid methanol.
    [0127] Another advantage associated with the present invention is that the integration of the methanol decomposition process in the loading phase (endothermic block) allows the process to present high synergies for the production of electricity and methanol from biomass. The medium-low temperature required for the methanol decomposition reaction process (in the endothermic reactor) allows the use of energy solar for operation even in geographical areas with moderate solar irradiation.
    [0129] On the other hand, the integration of the methanation process (in the endothermic reactor) in the discharge phase (endothermic block) allows the use of low-cost catalysts since high methane selectivity is not necessary. Furthermore, the presence of by-products does not affect the operation of the installation.
    [0131] Compared to state-of-the-art installations, which do not include the performance of methanation processes (therefore including streams of carbon monoxide and hydrogen), the present invention allows the use of the gas produced in conventional combustion systems, with stable combustion. and without the need to resize or modify the system. This advantage is associated with the use of methane in combustion, a fuel that is easier to burn in conventional devices in use today in industry, than a gas with hydrogen content (which requires the specific redesign of conventional equipment for its operation. , in addition to special requirements for working with hydrogen, which is a problematic gas in terms of handling and storage).
    [0133] Furthermore, according to the configuration used, the invention allows the recovery of energy through the turbine mounted downstream of the exothermic reactor as an added value with respect to solutions described in the state of the art.
    [0135] In general, in any system, there are efficiency losses associated with the storage process (due to sensible heat losses from the storage tank, the need to compress gases, etc.). In the system described, methanation allows the storage process (energy storage by breaking / creating chemical bonds) to be efficient thanks to the turbine arranged downstream of the exothermic reactor. By increasing the methanation pressure, it is also possible to obtain a higher temperature methanation reaction in the exothermic reactor with a consequent increase in system efficiency.
    [0137] The methanation process allows controlling the composition of the product to produce a gas with a low concentration of pollutants. If the installation is coupled to a solar field (thermal and photovoltaic) and the methanol is produced from biomass, generation in the complete cycle is renewable and does not add CO2 emissions to the net balance. If the installation is coupled to a combined cycle, the methanization heat can be used for superheating in the steam cycle.
    [0139] The invention introduces the novelty of being able to use renewable sources, such as thermal solar energy or biomass, as well as residual heat from processes, as a hot spot in the endothermic reactor. This energy input, which can be at medium-low temperature, is stored in the chemical bonds and can be recovered later.
    [0141] DESCRIPTION OF THE DRAWINGS
    [0143] To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of a practical embodiment thereof, a set of drawings is attached as an integral part of said description. where, for illustrative and non-limiting purposes, the following has been represented:
    [0145] Figure 1.- Shows a diagram of the installation and the path of the different fluid currents between elements of the installation.
    [0147] Figure 2.- Shows a view of a diagram of an embodiment in which the installation is coupled to a combined cycle. Only the elements of the installation that interact with the elements of the combined cycle have been represented.
    [0149] Figure 3.- Shows a view of a diagram of the steam cycle of the combined cycle of the example of figure 2.
    [0151] Figure 4.- Shows a view of a diagram of an embodiment in which the installation comprises an intermediate reheating block between the exothermic reactor and the turbine arranged downstream of the endothermic reactor.
    [0153] PREFERRED EMBODIMENT OF THE INVENTION
    [0155] Hereinafter, some embodiments of the present invention are described with the aid of FIGS. 1 and 4.
    [0156] An energy storage facility is proposed comprising an endothermic block and an exothermic block. As can be seen for example in figure 1, the endothermic block comprises at least one endothermic reactor (1) configured to receive a stream of methanol and heat (2) and produce a synthesis gas (3) by thermal decomposition of methanol. The exothermic block comprises at least one exothermic reactor (5) configured to receive a synthesis gas stream from the endothermic block and produce a methane-rich gas stream (6) by methanation at high pressure and high temperature. Likewise, the exothermic block comprises a heat engine (7) configured to receive the current rich in methane (6) and generate mechanical energy. Preferably the heat engine (7) is a turbine.
    [0158] The endothermic block can also comprise a compressor (4) configured to receive the synthesis gas (3) obtained from the endothermic reactor (1). In this embodiment the endothermic block further comprises a synthesis gas storage tank (8) configured to store the synthesis gas that has passed through the compressor (4).
    [0160] Also preferably in this embodiment the endothermic block additionally comprises a separator (9), located between the compressor (4) and the synthesis gas storage tank (8), and configured to separate liquid methanol from the synthesis gas stream that comes from the compressor (4). In separator (9) the incoming stream is cooled to room temperature. This allows the incoming methanol to condense.
    [0162] Likewise, the installation may comprise an additional compression train (10) located between the compressor (4) and the exothermic block.
    [0164] The installation may additionally comprise a mixer (12) configured to receive a stream of liquid methanol coming from the separator (9) and an incoming methanol stream (13). The mixer makes it possible to increase the mass flow of hydrogen in the discharge phase, so that the production of hydrogen can be integrated and the methanation reaction can be carried out in stoichiometric mode.
    [0166] In an alternative embodiment, the installation additionally comprises a pump located prior to the endothermic reactor (1) and configured to receive the current of methanol before being sent to said endothermic reactor (1). This embodiment enables the endothermic reaction to be carried out at high pressure and high temperature. It is necessary to have high temperatures to decompose methanol but the use of compressors is eliminated. It is a variant that allows to increase the performance of the installation and to integrate it with high efficiency with solar / residual heat at high temperature.
    [0168] The installation may also comprise additional heat exchangers for recovering heat from the system (11). Preferably it comprises a plurality of heat exchangers located in the endothermic block, in the exothermic block or between both.
    [0170] In an exemplary embodiment, it also includes a connection to a boiler, power cycle (14), chemical process or thermal process, configured to receive heat from the methane-rich gas stream (6) coming from the exothermic reactor (5) and receiving a stream of gas rich in methane after passing through the turbine (7).
    [0172] In this case, the installation can also comprise a second separator (15) configured to receive a stream of gas rich in methane after passing through the turbine (7) and remove the water from said stream before sending it to the boiler or power cycle ( 14).
    [0174] The endothermic block and the exothermic block operate simultaneously or decoupled in time.
    [0176] One of the keys to the invention is that the endothermic reactor (1) can use renewable energy as a heat source, selected from solar energy or biomass, or recovered waste heat. In this sense, the installation can be integrated with a solar concentrator, a biomass boiler, or systems for the recovery of residual heat from industrial processes. It may comprise a connection connected to the endothermic reactor (1) and configured to connect to a collection facility and receive a heat transfer fluid.
    [0178] Likewise, the object of the present invention is an energy storage method in the previously described installation. This method comprises the following stages:
    [0179] - thermally decompose a stream of methanol in the endothermic reactor (1);
    [0180] - carry out a methanation of the compressed synthesis gas in the exothermic reactor (5) and obtain a stream rich in methane at high pressure and high temperature;
    [0181] -send the stream rich in methane to a heat engine to generate mechanical energy and / or to a heat system and / or to a chemical process.
    [0183] In cases in which the installation has a compressor (4), the method comprises a stage in which the synthesis gas obtained in the endothermic reactor (1) is sent to a compressor (4) to compress said synthesis gas . It can also comprise stages of intermediate cooling of the compressed synthesis gas before the storage tank (8).
    [0185] In an embodiment of the invention, prior to the stage in which a stream of methanol is thermally decomposed in the endothermic reactor (1), it comprises a stage in which the stream of methanol is sent to a pump.
    [0187] As previously described, the endothermic reactor power source is a medium / low temperature heat source.
    [0189] Preferably the method comprises an intermediate stage in which the compressed synthesis gas is separated in the separator (9) to obtain a recirculated liquid methanol and compressed synthesis gas stream. Furthermore, the method comprises mixing an inlet methane stream with the recirculated liquid methanol stream and in which said stream is sent to the endothermic reactor (5).
    [0191] The stage in which the synthesis gas is compressed is carried out in phases in which the synthesis gas is passed through a plurality of compressors. Additionally, it includes sending synthesis gas to heat exchangers as it passes between compressors.
    [0193] Furthermore, the method comprises a stage in which the stream rich in methane gas that has been passed through the heat engine (7) is sent to a second separator (15), from which a stream of gas with a high methane content is obtained. and the water that has condensate, and in which the high methane gas stream is sent to
    [0194] a power cycle or external chemical or thermal processes.
    [0196] EXAMPLE 1
    [0198] As an example of the present invention an embodiment is described in an installation
    [0199] as shown in figure 1 with storage of the compressed gas at 50 bar. The
    [0200] Main data from Example 1 are shown in Table 1.
    [0202] In this case the methanation process takes place at 50 bar and 700 ° C, and there is conversion
    [0203] complete hydrogen in the methanation reaction. You can predict a
    [0204] performance in electrical recovery, defined as the ratio between the
    [0205] electrical production of the turbine downstream of the exothermic reactor and the work
    [0206] consumed in compression, 75%. In addition, the installation provides heat at high
    [0207] temperature, with a recovery value close to 100% of the thermal heat of
    [0208] input during the charging phase but with a temperature clearly above the
    [0209] contributed in the charging process (above 600 ° C).
    [0211] Table 1: Main data about the operating conditions on the sides
    [0212] endothermic, exothermic and in storage.
    [0214] Endothermic block value unit specifications
    [0215] incoming thermal power MW 10 reaction temperature ° C 315 reaction pressure bar 1 incoming methanol mol / s 100 percentage of methanol reacted% 100 storage
    [0216] pressure bar 50 temperature ° C 20 exothermic block
    [0217] thermal power produced MW 10.5 reaction temperature ° C 700 reaction pressure bar 50 syngas flow mol / s 300 mole fraction hydrogen - 0.667 mole fraction carbon monoxide - 0.334 percentage of reacted synthesis gas% 100 Other data required to carry out a simulated process in the installation are
    [0218] those shown below in table 2.
    [0220] Table 2: Main data used for the simulations of the process of the invention
    [0221] at installation.
    [0223] specifications unit value ambient temperature ° C 20 minimum temperature difference in heat exchangers ° C 20 isentropic efficiency of compressors - 0.87 isentropic efficiency of turbines - 0.9 mechanical efficiency - 0.98 liquid-gas separation temperature ° C 20 turbine discharge pressure bar 1
    [0225] The main results obtained are shown in the following table, which is the table
    [0226] 3.
    [0228] Table 3: Results of the simulations, in which the duration of the
    [0229] loading and unloading and performance values.
    [0231] specifications Unit value phase charge
    [0232] compression power MWel 4,5 net thermal power absorbed from the endothermic reactor MWth (315 ° C) 10
    [0233] duration h 12 phase
    [0234] download
    [0235] net electrical power produced from the turbine MWel 3,3 thermal power produced through the reaction
    [0236] MWth (700 ° C) 10.5 exothermic
    [0237] duration h 12 yields
    [0238] total efficiency - 0.967 thermal-thermal efficiency - 1.05 chemical-chemical efficiency - 0.971 electrical-electrical efficiency - 0.75 The power released during the discharge phase can also be regulated. The above data refer to a 12-hour charge phase in which only energy storage occurs, and a consequently 12-hour discharge phase, in which all previously stored energy is released.
    [0240] DEFINITIONS
    [0242] The total efficiency has been defined as the ratio between the outgoing and incoming energy flows in the absence of pressure drops or thermal losses in the components. The total return expression is given by:
    [0243] _ Eturb + ( Gp * LHVp) + Qexo
    [0244] n to t Qsol + Ecompr + ( Gmeth * LHVmeth)
    [0245] where the terms used are defined in table 4. The thermal to thermal performance only takes into account the relationship between the thermal flow entering the endothermic reactor and the release by the methanation process
    [0247] Qexo ( at 700 [° C])
    [0248] n th-to-th " Qsol ( at 315 [° C])
    [0249] The chemical-to-chemical performance takes into account only the relationship between the lower calorific value (LHV) of the synthesis gas produced from the methanization reactor and that of the methanol.
    [0250] ( Gp * LHVp)
    [0251] "Hch-to-ch ( Gmeth * LHVmeth)
    [0252] The electrical-to-electrical (or electrical recovery) performance expresses the ratio between the electrical power produced by the turbine and that used for compression.
    [0253] Eturb
    [0254] 1 | ei-to-ei E j-, bought
    [0256] Table 4: Definition of terms used in the calculation of returns and their values.
    [0258] symbol meaning unit value Eturb net power produced from the turbine MW 3.3 Ecompr net power absorbed by compression MW 4.5 Qsol net thermal power absorbed by endothermic reaction MW 10 Qexo net thermal power produced through reaction MW 10, 5 exothermic
    [0259] Gp syngas mass flow kg / s 1.95 LHVp lower calorific value of syngas MJ / kg 32 Gmeth mass flow rate of methanol kg / s 3.2 LHVmeth lower calorific value of liquid methanol MJ / kg 20.09
    [0261] EXAMPLE 2
    [0263] This example illustrates the coupling of the installation of the present invention to a combined cycle. The results of this embodiment of the invention refer to the design shown in figure 2 where only the exothermic block of the installation is shown. The endothermic block is identical to that described in the previous example. The excess heat generated during methanation (in the exothermic reactor) is used as a superheater (or superheater in another possible configuration) for the steam cycle (16). Said steam cycle (16) is shown in figure 3. The electrical efficiency has been calculated as the ratio between the outflow of electrical energy and all the incoming energy flows (thermal, electrical and chemical).
    [0265] specifications unit system value
    [0266] full
    [0267] gross electrical efficiency - 0.583 electrical power produced in the
    [0268] discharge MW 54.7 gas turbine
    [0269] optimum compression pressure bar 26 incoming air mass flow kg / s 65.2 incoming air temperature ° C 20 incoming air pressure bar 1 mole fraction of oxygen in air - 0.21 mole fraction of nitrogen in air - 0.79 compressor outlet temperature ° C 488 turbine inlet temperature ° C 1250 turbine outlet temperature ° C 511 type of combustion chamber - adiabatic reactor net electrical power produced MW 25.1 steam cycle
    [0270] type - no overheating pressure bar 280 maximum temperature ° C 620 mass steam flow kg / s 12.6 flue gas discharge temperature ° C 100 net electrical power produced MW 17.3 turbine
    [0271] discharge pressure bar 1 net electrical power produced MW 3.3
    权利要求:
    Claims (25)
    [1]
    1. - Energy storage facility characterized in that it comprises:
    -an endothermic block comprising at least:
    - an endothermic reactor (1) configured to receive a stream of methanol and heat (2) and produce a synthesis gas (3) by thermal decomposition of methanol;
    -an exothermic block comprising at least:
    - an exothermic reactor (5) configured to receive a stream of synthesis gas coming from the endothermic block and produce by methanation at high pressure and high temperature a stream of gas rich in methane (6);
    - a heat engine (7) configured to receive the current rich in methane (6) and generate mechanical energy.
    [2]
    2. - Energy storage facility according to claim 1 characterized in that the endothermic block comprises a compressor (4) configured to receive the synthesis gas (3) obtained from the endothermic reactor (1).
    [3]
    3. - Energy storage installation according to claim 1 characterized in that it additionally comprises a pump located prior to the endothermic reactor (1) and configured to receive the methanol stream before being sent to said endothermic reactor (1).
    [4]
    4. - Energy storage installation according to claim 2 characterized in that the endothermic block additionally comprises a synthesis gas storage tank (8) configured to store the synthesis gas that has passed through the compressor (4).
    [5]
    5. - Energy storage facility according to claim 4 characterized in that the endothermic block additionally comprises a separator (9), located between the compressor (4) and the synthesis gas storage tank (8), and configured to separate methanol liquid from the syngas stream coming from the compressor (4).
    [6]
    6. - Energy storage installation according to claim 2 characterized in that it may comprise an additional compression train (10) located between the compressor (4) and the exothermic block.
    [7]
    7. - Installation of energy storage according to any of the preceding claims characterized in that it may comprise additional heat exchangers for heat recovery of the system (11) located in the endothermic block, in the exothermic block or between both.
    [8]
    8. - Energy storage installation according to claim 5 characterized in that it additionally comprises a mixer (12) configured to receive a stream of liquid methanol from the separator (9) and an incoming methanol stream (13).
    [9]
    9. - Energy storage facility according to any of the preceding claims characterized in that it comprises a connection to a boiler, power cycle (14), chemical process or thermal process, configured to receive heat from the methane-rich gas stream (6) coming from the exothermic reactor (5) and receiving a stream of gas rich in methane after passing through the turbine (7).
    [10]
    10. - Energy storage installation according to claim 9 characterized in that it comprises a second separator (15) configured to receive a stream of gas rich in methane after passing through the heat engine (7) and remove the water from said stream before sending it to the boiler or power cycle (14).
    [11]
    11. - Energy storage facility according to any of the preceding claims characterized in that the heat engine (7) is a turbine.
    [12]
    12. - Installation of energy storage according to any of the preceding claims characterized in that the endothermic block and the exothermic block operate simultaneously or uncoupled in time.
    [13]
    13. - Energy storage facility according to any of the preceding claims characterized in that the endothermic reactor (1) uses renewable energy as a heat source, selected from solar energy, biomass, or recovered waste heat.
    [14]
    14. - Energy storage installation according to any of the preceding claims, characterized in that it is integrated with a solar concentrator, a biomass boiler, or systems for recovering waste heat from industrial processes.
    [15]
    15. - Energy storage facility according to any of the preceding claims characterized in that it comprises a connection connected to the endothermic reactor (1) and configured to connect to a collection facility and receive a heat transfer fluid.
    [16]
    16. - Energy storage method in the installation described in any of claims 1 to 16, characterized in that it comprises the following stages:
    - thermally decompose a stream of methanol in the endothermic reactor (1);
    - carry out a methanation of the compressed synthesis gas in the exothermic reactor (5) and obtain a stream rich in methane at high pressure and high temperature;
    -send the stream rich in methane to a heat engine to generate mechanical energy and / or to a heat system and / or to a chemical process.
    [17]
    17. - Energy storage method according to claim 16 characterized in that it comprises a stage in which the synthesis gas obtained in the endothermic reactor (1) is sent to a compressor (4) to compress said synthesis gas.
    [18]
    18. - The energy storage method according to claim 16, characterized in that before the stage in which a stream of methanol is thermally decomposed in the endothermic reactor (1), it comprises a stage in which the stream of methanol is sent to a pump .
    [19]
    19. - Energy storage method according to claim 16 characterized in that the energy source of the endothermic reactor is a medium / low temperature heat source.
    [20]
    20. - Energy storage method according to claim 16, characterized in that it comprises an intermediate cooling stage of the compressed synthesis gas before entering the storage tank (8).
    [21]
    21. - Energy storage method according to any of claims 16 to 20 characterized in that it comprises an intermediate stage in which the compressed synthesis gas is separated in the separator (9) to obtain a recirculated liquid methanol stream and synthesis gas compressed.
    [22]
    22. - Energy storage method according to claim 21 comprising mixing an inlet methane stream with the recirculated liquid methanol stream and in which said stream is sent to the endothermic reactor (5).
    [23]
    23. - Energy storage method according to any of claims 16 to 22 characterized in that the stage in which the synthesis gas is compressed is carried out in phases in which the synthesis gas is passed through a plurality of compressors.
    [24]
    24. - Energy storage method according to claim 23, characterized in that it additionally comprises sending synthesis gas to heat exchangers as it passes between compressors.
    [25]
    25. - Energy storage method according to any of claims 16 to 24, characterized in that it also comprises a stage in which the stream rich in methane gas that has been passed through the heat engine (7) is sent to a second separator ( 15), from which water and a second high-methane content gas stream are obtained, and in which said second high-methane content gas stream is sent to a power cycle or to external chemical or thermal processes.
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    同族专利:
    公开号 | 公开日
    ES2792748B2|2021-03-15|
    WO2020225467A1|2020-11-12|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    GB798741A|1953-03-09|1958-07-23|Gas Council|Process for the production of combustible gas enriched with methane|
    US20130025192A1|2011-07-26|2013-01-31|Battelle Memorial Institute|Solar thermochemical processing system and method|
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    PCT/ES2020/070286| WO2020225467A1|2019-05-08|2020-05-05|Installation for storing thermochemical-mechanical energy and energy storage method|
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