ES2568806B1 - Configuration of sensitive storage tanks and loading and unloading procedure - Google Patents

Abstract

Configuration of sensitive storage tanks and loading and unloading procedure. # Configuration of sensitive storage tanks having a first tank (2), a second tank (2 ') connected in series with the first tank (2), a conduction of hot heat carrier gas (3) and a cold heat carrier gas line (10). The first tank (2) and the second tank (2 ') have a bed (8, 8') of thermal storage. The first tank (2) has a circulation inlet pipe (5) connected to the hot heat carrier gas line (3), a circulation outlet pipe (7) connected to the cold heat carrier gas line (10), a recirculation inlet pipe (6) connected to the circulation outlet pipe (7) and a recirculation outlet pipe (4) connected to the hot heat carrier gas line (3). The second tank (2 ') has a circulation inlet pipe (5') connected to the hot heat carrier gas line (3) and a circulation outlet pipe (7 ') connected to the cold heat carrier gas line (10 ).

Description

CONFIGURATION OF SENSITIVE STORAGE TANKS AND CHARGING AND DISCHARGE PROCEDURE

Technical sector of the invention

The present invention is part of the thermal energy storage sector based on sensible heat of a solid material. In particular, it refers to an energy storage system capable of being charged and discharged by a heat transfer gas where energy is used to increase and reduce the temperature of the storage medium. The proposed storage system has application in solar thermal plants that use air, CO2 or any other gas as a heat transfer fluid, as well as for any other technology sector where the recovery of energy from high temperature gases is a factor of technical and economic interest .

BACKGROUND OF THE INVENTION There is currently great interest in the development of plants that take advantage of the solar resource for energy production. This has led to the development of solar plants that use air, CO2 or other heat transfer gases at high temperature (> 300 ° C) for energy production. Due to the nature of solar plants, these systems lack solar resources during the night and in periods of high cloudiness. It is of interest the ability to manage the energy perceived by the solar field during the hours of resource availability to increase the productivity of the plant (that is, to produce energy even in the hours when said resource does not exist, for example, during the night). The storage required by these types of plants must be able to exchange energy with the heat transfer gas working effectively and economically, thus being able to store a large amount of energy. During unloading, the storage module must provide the power block with heat transfer gas at the maximum operating temperature of the turbine, trying to ensure that the conditions of this heat transfer gas are stable and with the lowest possible head loss. This last factor is of special importance in power plants associated with a Brayton cycle. The power generated by these systems is significantly affected by the loss of load, being able to produce stops in the power block if it exceeds certain limit values. Energy regeneration systems from gases are widely known in the industry. These are based on refractory materials capable of withstanding high temperatures and capable of storing a large amount of energy. As a general rule, these materials have a low thermal conductivity (less than 10 W / mK) which, together with the low heat transfer rate associated with gaseous media, makes it difficult to transmit energy between the heat transfer fluid and the storage medium of energy This has led to the development of systems where the flow rate of the fluid is very low and the transfer area between the fluid and the contact area with the storage medium is very high, so that the transfer of energy can occur in a manner satisfactory For a good use of the material, systems are used in which the storage medium container has a connection for the passage of hot heat transfer gas (generally located at the top) and a different connection for the passage of cold heat transport gas (usually located on the bottom). During charging, the hot heat carrier gas is introduced through the hot connection and circulates through the bed, exchanging heat with it until it is removed by the cold connection. In this way a temperature distribution is achieved along the storage medium from the maximum working temperature to the minimum working temperature, there being a transition zone between them where the tennocline is found. The temperature gradient existing in this transition zone is called tennocline. The maximum and minimum storage operating temperature are defined by the cycle of each plant. With this, it is achieved that, during the discharge of the system, the heat transfer gas can be heated to the maximum working temperature regardless of the degree of loading of the storage system. It is intended that the loaded material is always in the upper zone to avoid generating a gas flow caused by the difference in temperatures that encourages the standardization of the temperature of the storage material, thereby losing the ability to recover useful energy. That is why the loading is done by the top of the equipment and the download by the bottom.

At present, storage tanks of a certain length are used where the area where the thermocline is located is a limiting factor when it comes to making the most of the thermal capacity of the tank. Therefore, it is necessary to minimize said area or eliminate it in such a way that 100% of the available solid storage material is used for the same length and

tank dimensions. Limitations on the operating conditions of the equipment

or losses of plant performance hinder the possibility of taking advantage of t 00% of the material, having to reach a compromise between storage utilization and the optimal operating conditions of the plant. In addition, working with a single storage tank has an associated loss of efficiency when working with partial loads. These losses can be avoided with the use of several tanks. That is, several tanks provide the system with greater manageability and allow systems with a large storage capacity. Within the configurations of several tanks, there is the option to connect the equipment in parallel or in series. If they are connected in parallel, the area where the thermocline is located would remain at the bottom of each tank, resulting in a worse operating performance. To improve this aspect, series connected tank systems are proposed, which require external pipes and connections to pass the heat transfer gas from one tank to the next. This solution is also not optimal in that a greater number of tanks implies greater losses of pressure and temperature by conduction of the heat-carrying gas from one tank to the next. A summary of the state of the art of storage tanks is presented below. Both W02013015834 and CN103547880 disclose a storage system composed of several tanks in series, each of which comprises an inlet and outlet of the heat transfer gas and a thermal storage medium permeable to the heat transfer gas, but in which the connections between a tank and Olro is made by external pipes, thereby increasing the loss of system load with respect to the present invention. The W02012127178 patent proposes a technical storage tank composed of a partitioned packed bed through which a heat transfer gas circulates, and which includes an inner conduit through which the heat transfer gas circulates and which includes a mechanically operated valve that diverges the flow of heat transfer gas to the storage material itself during the loading and unloading phases of the system. In addition, the flow of heat transfer gas through this internal conduction is carried out in the same direction as the flow of heat transfer gas when entering the tank. Unlike the present invention, this inner conduit has an additional complexity due to the need to use mechanically driven instrumentation and an internal meshing system

to contain the storage material and allow the circulation of the heat transfer gas through the partitioned packed bed. In solar plants it is usual to work with pressurized fluids, so that the container that stores the solid bed must be prepared to withstand the stresses caused by the pressure difference. The pressure, together with the high temperatures associated with the process, imposes severe requirements on the container tank. Thus, the invention differs from the state of the art, since it involves solving the problems associated with this type of storage systems by using tanks connected in series with an internal conduit formed either by the storage material itself or by a pipe. inside the same material as the material that forms the bed. That is, in the state of the art there are no tanks with internal ducts such as that of the invention in order to reduce conduction losses between the tanks and maximizing the use of the thermal capacity of the system by minimizing the area in which Tennocline is found. This allows to increase the manageability of the system allowing to minimize the partial loads of the storage and with it to improve the performance and the overall efficiency of the same.

Description of the Invention To solve the problem presented by configurations with tanks connected in series through pipes and external connections to pass the heat transfer gas from one tank to the next, the present invention proposes a storage tank system connected in series where Tanks are characterized by comprising an inner conduit that crosses it in such a way that the problems of pressure losses and thermal losses resulting in a lower performance of the thermal storage system are solved. In this way, it is possible to solve the problem of transporting the heat transfer gas from one tank to the next which, according to the prior art configurations, has pressure and temperature losses due to conduction of the heat transfer gas from one tank to the next one, which is undesirable since it affects a decrease in the performance of the thermal storage system. In order to solve the problems associated with conduction losses that decrease the temperature of the heat transfer gas inside the storage tank, it is of interest to have a system in which the length associated to the area where the thermocline is located is small with respect to the total length of the tank, so that the amount of storage material that experiences a variation in working temperatures between the maximum and minimum is as large as possible. This ensures maximum use of the heat capacity of the storage material for the same stored energy, and saves the amount of storage material for better performance. On the other hand, the power systems for which this type of storage is designed are very sensitive to the loss of load, implying a reduction in performance and generated power, being able to reach the system stop when reaching values of load loss limits. It is therefore critical to design a storage system that minimizes the loss of load associated with the exchange of energy without penalizing the performance of energy storage. When working with a single tank, the working gas or heat transfer gas is required to circulate throughout the entire amount of storage material, thereby increasing the loss of load. Using multiple tanks connected in series can reduce the loss of load by decreasing the amount of storage material that must pass through the heat transfer gas for the energy exchange to occur. As mentioned, this mode of operation is not optimal due to the use of an external conduit that connects the tanks and increases the thermal losses of the system. The system of the invention allows to optimize the thermal storage in a thermal energy generation system by using several smaller tanks more efficiently and with less load loss compared to a single equipment of larger dimensions and of equal capacity storage. By having a modular system, the manageability of the system is increased depending on the solar resource depending on the time of the year, allowing to minimize the partial loads of the storage and thereby improve the overall performance and efficiency of the same. The present invention relates to a configuration of at least two series sensitive storage tanks. Tanks can be placed vertically, horizontally or in other positions. Tanks must be able to thermomechanically withstand the stresses that occur both during the loading and unloading phases and during the time they are in

•

encapsulated to nominal or maximum working conditions. That is, the tanks must be able to withstand thermal and mechanical stresses and stresses in all phases of operation. The storage material can be placed directly inside the container or storage tank. This material or storage bed may be composed of a solid refractory material capable of withstanding temperatures greater than 30QoC, and more preferably greater than 1aoooe. The geometry of the storage material may vary depending on the need for transfer, it being desirable to increase the transfer area between the heat transfer gas and the material itself through a larger surface area. As non-limiting examples, storage materials such as alumina, cordierite, silicon carbide, molybdenum, zirconia, tungsten, in addition to any combination of these can be used. The storage material is arranged inside the tank so that there is an internal conduit arranged axially to the equipment in its central part. This inner conduit can be delimited by the storage material itself, in case it is a rigid material capable of being ordered. The duct is formed with pieces of the material designed so that when placed inside the equipment they enable an inner duct in the axial direction. The section of said inner conduit can be polygonal with three or more sides. In the event that the bed is formed by an unordered material, the inner conduit will be delimited by a tube or conduit of a material with the same thermomechanical properties as the bed material, mechanically resistant and capable of withstanding temperatures exceeding 300 ° C, more preferably greater than 1000oe. In this case, the section of the tube or conduit is

preferably circular or elliptical, being able to acquire any other geometry. This internal conduction allows to increase the flexibility in the modes of operation of the tank and, specifically, enables an operation method that optimizes the transmission of energy between the hot heat carrier gas and the storage material while reducing the loss of load experienced by the fluid. Said inner conduit completely crosses the tank, from the lower connecting pipe to the upper connecting pipe, without connecting to any of the two flow distribution chambers (upper chamber and lower chamber). In the event that the inner conduit is formed by the storage material itself, conduit segments are available that allow to complete said connections, formed by a mechanically resistant material and capable of withstanding temperatures higher than 300'C and more preferably higher at 1000 · C. The fact that the conduit is made of a material that has the same tennomechanical properties or same behavior as the storage bed is due to the fact that this eliminates the differential dilations that can structurally damage the bed and the conduit. Additionally, by forming the inner conduit with the same material, the resistance to technical stress caused by the temperature change during the use of this inner conduction is ensured. In addition, it is achieved that the thermal conductivity of the inner conduit is equal to that of the bed, avoiding the formation of thermal bridges in the thermocline zone that impair the loading and unloading of the system. By forming the inner conduit of a material that has the same properties or same behavior as that of the bed, it is achieved that the transmission of energy through the duct is minimal. The low conductivity of the material «10W / mK) is what makes a configuration with a lot of transfer area and low passing speed necessary to be able to transmit the energy. During the passage of the heat transfer gas through the interior conduit, the transmission of energy is not a desirable phenomenon, whereby the passage section of this interior conduction with respect to the passage section of the bed is reduced. In addition, the geometry of the interior conduction section offers a reduced transfer area, encountering conditions opposite to those of the bed, and thereby reducing energy transfer. For the correct distribution of the flow through the bed there are two flow distribution chambers located in the upper and lower part of the tank, respectively. The function of the chambers is to stabilize and homogenize the flow of calo carrier gas before entering the tank either from the top in load or from the bottom in discharge. If necessary, diffuser elements will be included for the correct homogenization of the flow. Each of these chambers has a bed connection pipe for the entrance or exit of heat-carrying gas with which it connects with the power cycle. The lower chamber has a bed support structure that prevents the passage of the particles that make up the bed, allowing instead the passage of heat transfer gas from the chamber and capable of supporting the weight of the storage material column and transmitting it to the structural outer layer (outer shell). This can be achieved using a perforated disk.

•

with holes with a diameter smaller than the diameter of the particles of the material that makes up the bed. The separation between 105 holes must comply that under no circumstances all of them are clogged by particles. Within the scope of the present invention, it is defined as the maximum working temperature at the maximum temperature at which the storage system works, being higher than 7000C, and preferably higher than 1oooce. The minimum working temperature is the minimum temperature at which the storage system works, equal to or less than 450 ° C. The threshold temperature in charge is also defined as the temperature of the heat transfer gas at the exit of the storage at which the thermocline transmission phase begins to be charged between that tank and the adjacent one, between 3500C and 700 ° C, while the Threshold temperature in discharge will be the temperature of the heat transfer gas at the outlet of the storage at which the thermocline transmission phase begins to discharge between that tank and the next one, between 600 ° C and 950 ° C. The charge completion temperature is defined as the temperature of the heat transfer gas at the exit of the last tank at which the charging process is completed, between the minimum working temperature and the maximum working temperature, preferably between 350 ° C and 600 ° C The discharge end temperature is defined as the temperature of the heat transfer gas at the outlet of the first tank at which the discharge is completed, between the maximum working temperature and the minimum working temperature, preferably between 7000C and 950'C. The procedure for loading and unloading the entire storage system is described below.

The loading procedure is carried out in two phases: a first, called a tank load and a second called a thermocline transmission phase in charge. At the beginning of the loading of the system the tanks are completely unloaded, the temperature of the bed or storage material being equal to the minimum working temperature. During the tank loading process, the heat transfer gas passes through the hot heat carrier gas line at the maximum working temperature and is introduced into the tank

through the upper pipe connecting to the storage bed. The heat transfer gas exchanges energy with the material or storage bed leaving it through the lower pipe connecting to the bed at a minimum working temperature and is returned to the cycle through the cold heat carrier gas line. During this process the heat transfer gas circulates exclusively through a tank or first tank. As the system is loaded, the transition zone between the maximum temperature and the minimum working temperature (zone where the thermocline is located) in the first tank moves through the bed from the upper zone to the lower zone (see Figure 3), keeping the outlet temperature constant until it reaches the lower zone. At that time the temperature at the outlet increases sequentially until a threshold temperature is reached. Figure 3 shows the loading process where you can see the beginning of the load, the load in an intentional phase, the operational end of the load and the optimal end of the load, highlighting in scratch the additional volume that would allow the optimal load . When the threshold temperature in charge is reached, the thermocline transmission phase in charge starts. For this, the system is aligned in such a way that the lower flow distribution chamber is connected with the lower connecting pipe of the same tank. The heat transfer gas leaving the lower part of the bed of the first tank travels through all the vertical interior conduit until it exits the top part of the tank, connecting again with the hot heat transfer gas line. This hot heat carrier gas line transports the heat carrier gas to the upper pipe connecting to the bed that connects to the adjacent tank bed or second storage tank. The heat transfer gas circulates through the storage bed of the second tank until it is extracted through the bottom pipe connecting to the bed and returned to the cycle through the cold heat carrier gas line. This situation continues until the outlet temperature of the first tank is equal to the maximum cycle temperature, at which time the first tank will be considered fully charged. At that time, all the connection valves of the first tank are closed, leaving the tank encapsulated, and the loading of the adjacent tank or second storage tank is continued. During the transmission process of the thermocline in charge, the heat transfer gas circulates through two tanks, the tank that is being fully charged, the first tank, and the tank that is being charged.

passing the thermocline, second tank.

The loading and transmission phases of the thermocline in charge follow each other until the last tank is reached: if the configuration is two tanks, the last tank is the second, if the configuration is three tanks, the last tank is the third , and so on. The charging process will be terminated when the temperature of the heat transfer gas from the last tank is equal to or greater than the charge completion temperature. At this point all the tanks are fully loaded except for the last tank that will have the area where the thermocline is located at the bottom of it, being considered so! The fully charged system. During the entire loading process and regardless of the number of tanks that make up the storage system, the maximum load loss is that associated with the thermocline transmission process under load.

Similarly to the load, the discharge consists of two phases: a first one called the discharge phase and a second one called the transmission phase of the thermocline in discharge. At the beginning of the discharge of the system the tanks are fully charged, where the temperature of the storage bed is equal to the maximum working temperature. During the discharge process, the heat-carrying gas passes through the cold heat-carrying gas conduit at the minimum working temperature and is introduced into the tank through the bottom pipe connecting to the bed that connects to the storage bed itself. The cold heat exchanger gas exchanges energy with the storage material leaving it through the upper pipe connecting to the bed at the maximum working temperature and is sent to the cycle through the hot heat carrier gas line for energy production. During this process the heat transfer gas circulates exclusively through a tank. As the system is discharged, the zone where the thermocline is located moves through the bed from the lower zone to the upper zone. The temperature at the exit of the bed remains constant until the area where the thermocline is located reaches the top of the bed. At that time the temperature at the outlet decreases sequentially until a minimum working temperature is reached. When this occurs, the discharge thermocline transmission phase begins. For this purpose, the heat transfer gas from the upper flow distribution chamber of the second tank is introduced into the inner conduit of the adjacent tank, the first tank, through the hot heat carrier gas line. This conduit carries the heat transfer gas to the lower pipe connecting to the bed that connects with the bed of the adjacent tank, the first tank, circulating through the bed until it is extracted by the upper pipe connecting to the bed and sent to the cycle through the hot heat carrier gas line. This situation continues until the outlet temperature of the second tank is equal to the minimum cycle temperature, at which time the second tank will be considered to be fully discharged. At this moment, all the connection valves of the second tank are closed, leaving the tank encapsulated, and the discharge of the adjacent tank, the first tank, continues. During the discharge thermocline transmission process the heat transfer gas circulates through two tanks, first and second tanks. The discharge and transmission phases of thermocline in discharge follow each other until the first tank is reached. The discharge process will be terminated when the temperature of the gas carrying the first tank outlet is equal to or less than the discharge completion temperature. At this moment all the tanks are totally unloaded except the first tank that will have the area where the thermocline is located at the top of it, thus considering the system totally unloaded. During the entire unloading process, and regardless of the number of tanks that make up the storage system, the maximum load loss is that associated with the discharge thermocline transmission process (two tanks). The number of tanks will be equal to or greater than two, with at least two being necessary.

In this way, an optimal use of the storage material is achieved by avoiding having to circulate the carrier heat gas throughout the storage material. With this, the pressure losses in the working fluid are

reduce significantly, resulting in greater performance in the power block.

The present invention comprises both the equipment and the connection between the equipment and its operation for the optimal use of the storage material, as well as the reduction of the loss of load in the heat transfer gas as it passes through the storage bed. These connections allow the transmission of the area where the thermocline of a tank to the next one is located, maximizing the energy storage capacity of the system and reducing the associated load loss. In the event that the storage system is not fully discharged, loading begins with the tank in which the area where the thermocline is located, circulating all the gas stream

heat carrier through the tank until the outlet temperature is equal to or greater than the threshold load temperature at which time the process of transmission of the thermocline in charge to the adjacent tank or the system is considered fully charged as applicable.

In case the storage system is not fully charged The download will begin by the tank in which the area is located where the thermocline is located, circulating all the current of calo carrier gas through the tank until the outlet temperature is equal to or lower than the temperature discharge threshold, at which time the transmission process of thermocline in discharge to the adjoining tank or the system is considered fully downloaded as applicable.

Brief description of the drawings For a better understanding of the invention figures are included in which, a illustrative but not limiting mode different characteristics of the in vención Figure 1 is a schematic of a configuration of the invention with two tanks. Figure 2 is a schematic of a tank of the invention. Figure 3 is a diagram of the evolution of thermocline during charging. Figure 4A is a diagram of a tank with an ordered bed that conforms to the interior duct. Figure 48 is a schematic of a tank where the interior conduction and the bed Messy are of the same material. Figure 5 is a schematic of a configuration of the invention with three tanks.

The references: Set 1 of 2, 2 'tanks First tank 2 2nd tank 2 ' Third tank 2 " Conduction of hot heat carrier gas 3 Recirculation outlet pipe 4 or upper connection pipe Circulation inlet pipe 5 or upper bed connection pipe Recirculation inlet pipe 6 or lower connection pipe

Circulation outlet pipe 7 or lower connection pipe to the bed Bed 8 Inner conduction 9 Conduction of cold heat carrier gas 10 Container 11 Inlet chamber 12, 12 'to bed 8, 8' Outlet chamber 13, 13 'of bed 8, 8 'Support structure 14, 14' of bed 8, 8 '

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a tank system that optimizes thermal energy storage while reducing system load loss. With the configuration of equipment and connections presented below, it is possible to solve the problems associated with the storage of thermal energy from a flow of heat transfer gas at high temperature (> 4500C) and high pressure (> 5 bar). According to an example of the invention, the heat transfer gas is air. In a preferred embodiment, the storage system is comprised of a hot heat carrier gas line 3, a cold heat carrier gas line 10, a set 1 of tanks 2, 2 ', a set of pipes 4, 5 connecting each tank 2 , 2 'with the hot heat carrier gas line 3 and a set of pipes 6, 7 that connect with the cold heat carrier gas line 10. Each tank comprises a preferably cylindrical container 11 with a semi-elliptic or semi-spherical top bottom and a semi-elliptic bottom bottom or hemispherical. The container 11 can also adopt any polygonal section. Tank 2, 2 'will be placed mainly in an upright position. In vertical position the energy transfer is optimized. Said container 11 is composed of an inner conduit 9, an upper connecting pipe 4 and a lower connecting pipe 6 that connect with said inner conduit, a bed formed by the storage material 8, which can be alumina, an upper chamber 13 and lower chamber 12 that distributes and homogenizes the circulating flow through the storage material, and an upper pipe connecting to bed 5 and lower pipe connecting to bed 7 that connect with said distribution chambers. In order to keep the lower chamber 12 clear, there is a support structure 14 of the bed 8 capable of supporting the weight of the solid bed column and transmitting the stresses to the container 11. Each tank 2 is connected to the system in such a way that the upper connecting pipe 4 that connects with the inner conduit 9 connects with the hot heat carrier gas line 3, the upper connecting pipe to the bed 5 connecting with the upper chamber 13 connects also with the hot heat carrier gas line 3, while the bottom connecting pipe 6 and the bottom connecting pipe to the bed 7 connect on one side with the lower chamber 12 and on the other with the cold heat carrier gas line 10. One embodiment of the invention relates to a thermal energy storage system for air at temperatures above 450 ° C, and more preferably working temperatures between 4500 e and 1000oe, working at a pressure greater than 5bar, and more preferably greater than 20bar. In accordance with this embodiment of the invention, the storage system is composed of:

•

two tanks containing storage material with an upper bed connection pipe for hot heat carrier gas and a lower bed connection pipe for cold heat carrier gas and connected with the inner storage bed, an inner conduit and an upper pipe and lower connection that connect with said inner conduit. The tanks must be capable of thermomechanically supporting the stresses that occur both during the loading and unloading phases and during the time in which they are encapsulated at nominal or maximum working conditions. Each of the tanks comprises a bed formed by a thermal storage material of refractory nature capable of withstanding high temperatures and arranged in such a way as to maximize the thermal transfer between the heat transfer gas working with said material.

•

A hot heat transfer gas line.

• A line of cold heat transfer gas. The loading process begins with the storage system fully discharged. During charging, the hot air circulates at 10000C through the first tank exchanging energy with the storage material until it exits the bottom pipe connecting to the bed at a temperature of 450oe, being returned to the cycle by the line of cold heat-carrying gas.

When the outlet temperature of the first tank is equal to or greater than the threshold temperature at load, around 50QoC the thermocline is considered to be located at the bottom of the tank. At this moment the thermocline transmission phase to the adjacent tank begins. To do this, the outgoing air from the bed of the first tank is connected to the internal conduit thereof, said air leaving the upper pipe connecting to the bypass that connects with the internal conduction and being led to the adjacent tank through the gas line hot heat carrier. This process continues until the outlet temperature of the first tank is equal to 1 aoooe, at which time the connections of said tank are cut, leaving it encapsulated, and continuing with the loading of the adjacent tank. The loading and transmission processes of thermocline in charge to the adjacent tank are repeated until all the tanks except the last one are fully loaded. The charging process will be terminated when the temperature of the outlet air of the last tank is equal to or greater than 6000C. In case the storage system is not fully discharged, loading begins with the tank in which the area where the thermocline is located, circulating all the air flow through the tank until the outlet temperature is equal to greater than 5000C, at which time the process of transmission of the thermocline in charge to the adjacent tank is started or the fully charged system is considered as applicable. The download process begins with the fully loaded storage system. During the discharge the cold air circulates at 4500C through the second tank exchanging energy with the storage medium until it exits through the upper pipe connecting to the bed that connects with the storage bed at a temperature of 10000C and being returned to the cycle by the Hot heat carrier gas line. When the outlet temperature of the second tank is equal to or less than 9000C, the thermocline is considered to be located at the top of the first tank. At this point the process of thermocline transmission to the adjacent tank, first tank, begins. The outgoing air from the bed of the second tank is connected to the internal conduction of the adjacent tank, first tank, through the hot heat carrier gas line. The air travels through said internal conduit until it exits the bottom, connecting there with the lower chamber that connects to the bed of the adjacent tank, first tank. The air travels through the bed until leaving the adjoining tank, first tank, at a temperature equal to 10000C, being returned to the cycle through

the hot heat carrier gas line. This process continues until the temperature

output of the second tank is equal to 450'C, at which time the

connections of said tank, leaving it bottled, and continuing with the loading of the adjacent tank. The discharge and transmission processes of thermocline in discharge to the adjacent tank are repeated until all the tanks are fully unloaded. The discharge process will be completed when the temperature of the last air outlet of the last tank is equal to or lower than 80oC. In case the storage system is not fully charged, the discharge will begin by the tank in which the area where the thermocline is located, circulating all the air flow through the tank until the outlet temperature is equal to less than 900 ° C, at which time the process of thermocline transmission discharge to the adjacent tank is started or the fully discharged system is considered as applicable.

In accordance with the previous preferred embodiment, the invention relates to a configuration of sensitive storage tanks having:

to)

a first tank (2) comprising an inner conduit (9) configured

to allow a heat transfer gas to pass,

b)

a second tank (2 ') connected in series with the first tank (2).

According to other features of the invention, the configuration may comprise:

a) a hot heat transfer gas line (3);

b) a cold heat transfer gas line (10);

e) the first tank (2) and the second tank (2 ') comprise a bed (8, 8') of

thermal storage;

d) the first tank (2) comprises:

d1) a first circulation inlet pipe (5) connected to the hot heat carrier gas line (3); d2) a first circulation outlet pipe (7) connected to the cold heat carrier gas line (10); 2d3) a recirculation inlet pipe (6) connected to the circulation outlet pipe (7); d4) a recirculation outlet pipe (4) connected to the conduit of

hot heat carrier gas (3);

d5) an inner conduit (9) between the recirculation inlet pipe (6) and

the recirculation outlet pipe (4).

e) the second tank (2 ') comprises:

5

e1) a second circulation inlet pipe (5 ') connected to the

conduction of hot heat carrier gas (3);

e2) a second circulation outlet pipe (7 ') connected to the

conduction of cold heat transfer gas (10);

The tank (2, 2 ') may comprise an inlet chamber (12, 12') to the bed (8, 8 '),

the

between the circulation inlet pipe (5, 5 ') and the bed (8, 8').

The tank (2, 2 ') may comprise an exit chamber (13,13') of the bed (8, 8 '),

between the bed (8, 8 ') and the circulation outlet pipe (7, 7').

The tank (2, 2 ') may comprise a support structure (14, 14') of the bed (8,

8 ').

fifteen

The bed (8) can be ordered and the inner conduit (9) can be shaped

by the bed itself (8).

The bed (8) can be unordered and the inner conduit (9) can be formed

by a pipe of a material that has the same thermomechanical properties

than the bed.

twenty

The heat transfer gas can be air.

The bed (8, 8 ') can be of a refractory material configured to support

temperatures above 300 ° C.

The bed (8, 8 ') can be made of alumina.

25

The inner conduit (9) is of polygonal section of three or more sides.

The inner conduit (9) is a tube of circular or elliptical section.

According to another preferred embodiment, the tank configuration of

Sensitive storage consists of three tanks (2, 2 ') connected in series where

30

at least two first tanks (2) comprise an inner conduit (9)

configured to allow a heat transfer gas to pass through.

The invention also relates to a method of loading the configuration of

Sensitive storage tanks described above characterized by that

35

understands:

.

to)

a tank load (2, 2 ');

b)

a thermoelin transmission in charge;

and)

A charge completion.

The invention also relates to a procedure for downloading the configuration of sensitive storage tanks described above characterized by which includes: a) a tank discharge (2, 2 '); b) a discharge thermocline transmission; e) a completion of the download.

According to other characteristics of the methods of the invention: The loading of the first tank (2) comprises circulating heat transfer gas through the first tank (2) until a threshold temperature is reached.

The thermocline transmission on load comprises: a) recirculating heat transfer gas through the inner conduit (9) of the first tank (2); b) circulating ealoporter gas through the second tank (2 '); e) until an outlet temperature of the first tank (2) is equal to one

maximum working temperature, to get the first tank (2) loaded.

The discharge of the second tank (2 ') comprises circulating heat transfer gas through the second tank (2 ') until a minimum working temperature is reached. The discharge thermocline transmission comprises: a) introduce heat transfer gas from the second tank (2 ') to the pipeline

inside (9) of the first tank (2);

b) until an outlet temperature of the second tank (2 ') is equal to a minimum working temperature, to obtain the second tank (2') discharged.

Claims (19)

 Claims

1. Configuration of sensitive storage tanks comprising at least

two tanks (2, 2 ') connected in series characterized by at least the first

5

tank (2) comprises an inner conduit (9) configured to allow a passage

of a heat transfer gas.

2. Configuration of sensitive storage tanks according to claim 1,

characterized by comprising:

10

2nd) a hot heat transfer gas line (3);

Zb)

a cold heat transfer gas line (10);

where:

Zc)

the first tank (Z) and the second tank (Z ') comprise a bed (8, 8') of

thermal storage;

fifteen

Zd) The first tank (Z) comprises:

2d1)

a first pipeline from entry from circulation (5) connected to the

conduction of hot heat carrier gas (3);

2d2)

a first pipeline from exit from circulation (7) connected to the

conduction of cold heat transfer gas (10);

ZO

Zd3) a recirculation inlet pipe (6) connected to the pipe of

circulation outlet (7);

2d4)

a recirculation outlet pipe (4) connected to the conduction of

hot heat carrier gas (3);

Ze)

The second tank (Z ') comprises:

25

2e1) a second pipeline circulation input (5') connected to the

conduction of hot heat carrier gas (3);

ZeZ)

a second pipeline from exit from circulation (7 ') connected to the

conduction of cold heat transfer gas (10);

30

3. Configuration of sensitive storage tanks according to claim 2,

characterized by driving

interior (9) is connected to the pipe

recirculation inlet (6) and the recirculation outlet pipe (4).

4. Configuration of sensitive storage tanks according to claim 2,

35

characterized in that the tank (Z, Z ') comprises an inlet chamber (1Z, 1Z')

to the bed (8, 8 '), between the circulation inlet pipe (5, 5') and the bed (8, 8 ').

5.

Configuration of sensitive storage tanks according to claim 2, characterized in that the tank (2, 2 ') comprises an exit chamber (13, 13') of the bed (8, 8 '), between the bed (8, 8' ) And the circulation outlet pipe (7, 7 ').

6.

Configuration of sensitive storage tanks according to claim 2 characterized in that the tank (2, 2 ') comprises a support structure (14, 14') of the bed (8, 8 ').

7.

Configuration of sensitive storage tanks according to claim 2, characterized in that the bed (8) is arranged and the inner conduit (9) is formed by the bed (8).

8.

Configuration of sensitive storage tanks according to claim 7 characterized in that the inner conduit (9) is of polygonal section of three or more sides.

9.

Configuration of sensitive storage tanks according to claim 2 characterized in that the inner conduit (9) is a tube of a material with the same thermomechanical properties as the bed (8).

10.

Configuration of sensitive storage tanks according to claim 9 characterized in that the inner conduit (9) is a tube of circular or elliptical section.

eleven . Configuration of sensitive storage tanks according to claim 1 characterized in that the heat transfer gas is air.

12.

Configuration of sensitive storage tanks according to claim 2 characterized in that the bed (S, 8 ') is of a refractory material configured to withstand temperatures above 300 ° C.

13.

Configuration of sensitive storage tanks according to claim 2 characterized in that the bed (8, 8 ') is made of alumina.

14.

Configuration of sensitive storage tanks according to claim 1 consisting of three tanks (2, 2 ', 2 ") connected in series characterized by the fact that minus the first and the second tank (2, 2 ') comprise an inner conduit (9) configured to allow a heat transfer gas to pass through.

fifteen.

Loading procedure for storage tank configuration sensitive of any of the preceding claims characterized in that understands: 15a) a tank load (2, 2 '); 15b) a thermocline transmission in charge; 15c) a charge completion.

16.

Procedure for downloading storage tank configuration sensitive of any of the preceding claims characterized in that understands: 16a) a tank discharge (2, 2 '); 16b) a discharge thermocline transmission; 16c) a download completion.

17.

Loading procedure for storage tank configuration sensitive according to claim 15 characterized in that the loading of a first tank (2) comprises circulating gas carrier through the first tank (2) up to reach a threshold temperature in charge.

18.

Loading procedure for storage tank configuration sensitive according to claim 15 characterized in that the transmission of Thermocline in charge includes: 18a) recirculating heat transfer gas through the inner conduit (9) of the first tank (2); 18b) circulating gas e.porter through the second tank (2 '); 18c) until an outlet temperature of the first tank (2) is equal to one

maximum working temperature, to get the first tank (2) loaded.

19.

Procedure for unloading the configuration of sensitive storage tanks according to claim 16 characterized in that the discharge of the tank

(2 ') comprises circulating heat transfer gas through the second tank (2') until a minimum working temperature is reached. 20. Procedure for downloading storage tank configuration Sensitive according to claim 16 characterized in that the discharge thermocline transmission comprises: 20a) introducing heat transfer gas from the second tank (2 ') to the conduction inside (9) of the first tank (2); 20b) until an outlet temperature of the second tank (2 ') is equal to a minimum working temperature, to obtain the second tank (2') discharged.