CN101952564A

CN101952564A - The equipment and the method that are used for heat energy storage

Info

Publication number: CN101952564A
Application number: CN2008801270528A
Authority: CN
Inventors: R·希纳尔
Original assignee: Research Foundation of City University of New York
Current assignee: City University of London; Research Foundation of City University of New York
Priority date: 2007-12-21
Filing date: 2008-12-19
Publication date: 2011-01-19
Also published as: MX2010007025A; BRPI0819515A2; EP2235341A1; EA201001060A1; WO2009082713A1; IL206505A0

Abstract

Be used for requiring big energy storage source to satisfy the method and apparatus of the industrial system store heat of working load, by using the thermal technology to make fluid as the thermal fluid of steam form and its heat content is deposited on the liquid phase of the cooling and the condensation of removing this thermal fluid on the heat-storage medium then, come the heat content of store heat working fluid, and when needing the thermal technology to make fluid once more, make liquid heat transfer fluid return heated storage medium and its during through overheated storage medium by heat again, return work system then so that be used as the thermal technology and make fluid.

Description

The equipment and the method that are used for heat energy storage

The cross reference of related application

The application is 61/063 according to the sequence number that united states patent law the 119th (e) bar requires to submit on January 31st, 2008,467, the sequence number that on March 17th, 2008 submitted is 61/069,778, the sequence number that on March 17th, 2008 submitted is 61/069,779, the sequence number that on September 15th, 2008 submitted is 61/097,043, the sequence number that on July 23rd, 2008 submitted is 61/083,005, the sequence number that on July 23rd, 2008 submitted is 61/083,051, the sequence number that on August 4th, 2008 submitted is 61/086,055, the sequence number that on November 18th, 2008 submitted is 61/115,831, the sequence number that on December 21st, 2007 submitted is 61/008, the preference of 635 patent application, the content of these patent applications are clearly incorporated among the application by reference in full.The application still be the sequence number of submitting on March 6th, 2008 be 12/066, the part continuation application of 054 application, sequence number is 12/066,054 application is that the sequence number that requires to submit on March 8th, 2007 according to united states patent law the 119th (e) bar is 60/905, the sequence number of submitting on July 27th, 2007 of the preference of 729 application is the national stage of the international application of PCT/US07/74646, and the application is 60/834 according to the sequence number that united states patent law the 119th (e) bar requires to submit on August 1st, 2006 still, the sequence number in application on July 27th, 2007 of the preference of 736 application is the part continuation application of the international application of PCT/US07/74647, and the disclosure of these applications is clearly incorporated among the application by reference in full.

Technical field

The present invention relates in general to the method and apparatus that is used for heat energy storage, and more specifically, the method and apparatus that is used for heat accumulation that the present invention relates to particularly in the industrial generation system, use.

Background technique

The demand of storage of energy that maybe can produce electric power to electric power is very big.In some sense, mineral fuel are the sunlight that is stored.Electrochemical cell is fit to stored energy so that fetch later on, and for example electrochemical cell can be used for household goods, small appliances and even is used for electric vehicle.But aspect size and cost, these major parts are small-scale application.

But more large-scale power generation applications can not satisfy fully by electrochemical storage cell.These uses comprise store be used for generator set maybe will be with the power of other big machinery of stored energy drives.We are called these " on a large scale " application or " industry " uses.In power network, hydroelectric power is used to the energy that provides stored as required usually and can realizes being used to regulating the Steam Generator in Load Follow fast that electrical network changes.But these large-scale application can not be provided the electrochemistry deposit effectively by cost, and the water power reserve capabillity still is confined to particular locality and local condition.Energy also can be used as steam and is stored.Known a kind of commercial run that is used to store steam, this method are stored in the pipeline by the boiling water that will pressurize and generate electricity and finish by reducing pressure, reduce the steam raising that pressure makes boiling point descend and a part is stored.But this causes significant free energy loss owing to the steam that is obtained has lower temperature and pressure, and it is the low expensive methods of a kind of thermal efficiency.But this method is feasible.

The pump drawing type that is similar to water power is stored under the situation that geological condition allows and is put into practice widely, but it only has mid-efficiency.Also can use pressurized air, but it only has mid-efficiency and cost is higher.Not can be used at present satisfy the method for the extensive demand of supporting electrical network.

In addition, be understandable that: the workload demand on the electrical network is by day with big and lower at night and weekend at dusk.In the past, this heavy load is can change power output fast and the generator set that can significantly not lose efficient solves by design.Except that the hydroelectricity generator group, the steam electric power unit with boiler has this ability with the turbine with big adjusting ratio.They start time-consuming (up to half a day), but they can be at about 13% operation and efficient height still of its full capacity, and can change their output fast so that carry out Steam Generator in Load Follow or Load Regulation on the electrical network.But, want effective words, comparing this with the average size of unit needs big overload capacity.This overload capacity coefficient is about 1.5 to 2 in the power generation system that we use.But the generation current unit is not kept this surplus capacity.

Generator set can be operated and the maximum capacity and the ratio between the minimum capacity that can significantly not lose efficient is called adjusting than (turndown ratio).For the coal power generation unit of routine, design specification requires 8: 1 minimal adjustment ratio.These units once were used as the effective supplier and the attemperator of electric power on the electrical network that is provided with enough overload capacities.

But demand constantly increases, but does not build new unit to catch up with this speed that increases.On the contrary, surplus capacity becomes the part of the capacity of regular use simply.In addition, though current coal power generation unit than more effective before 50 years, their every kWh runnings become more expensive generally, have significantly increased their cost because reduce the needs of pollution.

Because the loss of this overload capacity, the source that needs to find excess energy is satisfied peak demand and is used for the electrical network adjusting.

In addition, when the overload capacity of electrical network reduced greatly, the variability of electric grid operating significantly increased.This has caused severe supply and control crisis.We not only have new operation technique, such as the air conditioning that has in use increased load more variablely and quite a lot of, and we have novel variable energy source now, such as wind turbine, solar cell and the concentration solar generating (CSP) that can cause the danger fluctuation on the electrical network.

Though the CSP generator set is even as big as making its economy and practicably being provided with extensive storage, major part can not be done like this, particularly fused salt, solar cell and wind.A kind of mode of tackling this state is to build the steam electric power unit more how soon speed responds, to increase overload capacity and quick response so that supply and regulate electrical network.But build new generator set is very long process and very expensive.Therefore the alternative solution that can increase capacity and controllability will be welcome.

Another reason to the increase in demand that stores is that generation technology changes.Response that the nuclear power generation unit has slowly manyly and the low ratio of regulating.Combined cycle generation unit (CCPP) also has very low adjusting ratio, but for rock gas, therefore they have than any other is also come into operation based on the much higher efficient of the generator set of mineral fuel (37-45% of 60% pair of coal).The CCPP technology is based on the high-temperature fuel gas turbine, and its thermal exhaust is supplied to the boiler that produces the steam that is used for steam turbine.These units provide whole world a big chunk electric energy and their use to increase (reaching more than 20% of electric motor power in the U.S.) fast.Problem is that gas turbine has very low adjusting ratio, loses efficient very fast when electric power is lower than greatest requirements.Only control is on-off basically, because they can be shut down in one hour and starting in to two hour.Carry out quick load and follow the tracks of but they are not suitable for electrical network regulated, and in fact not have enough overload capacities to realize this operation.

For integrated gasification combined cycle plants (IGCC) generator set, in fact only clean enough is to be added into the coal fired power generation unit of the current electrical network of the U.S., and situation is like this equally.These are basic combined cycle generation units, and wherein gas is not rock gas, but the product of coal gasifier.One of problem of IGCC is that its adjusting is lower than very, so its quick load follow-up capability is low.Once more, the demand of electrical network adjusting is not met.

Therefore, be understandable that: still need the novel energy stocking system that can help to solve above-mentioned supply and control problem badly.The present invention solves the one or more problems relevant with having heat reservoir now, and relates to these and other purposes that is used for stored energy.

Summary of the invention

The invention provides and be used for the most highlightedly in industrial system, requiring big energy storage source to satisfy working load, for example be used for driving the turbine of generator set at the method and apparatus of industrial system heat accumulation.The present invention has overcome the heat accumulation restriction and in fact can be implemented in the exercisable in fact any temperature heat accumulation of most of generator set.Compare with other heat-storing method that is used for large-scale application, the present invention is simple in design and more firm, and implements and operate more cheap.

In an example, using the thermal technology to finish the system of work as being used for making pump work or driving turbine of system as fluid, for example, wherein the present invention's instruction: be deposited on the heat-storage medium as the thermal fluid of steam form and with its heat content by using the thermal technology to make fluid, remove the liquid phase thermal fluid of cooling this moment and condensation then---can remove to keeping jar, store the heat content that this thermal technology makes fluid.When needing the thermal technology to make fluid once more, liquid heat transfer fluid be back to heated storage medium and its during through overheated storage medium by heat again, be back to work system then and be used as the thermal technology when needed and make fluid.

In various embodiments, we instruct the thermal fluid of use about temperature T a or temperature T a that the system and method for stored heat is provided, its exemplary system and method comprises: the ceramic heat-storage medium with vertical section of prolongation of axis extension longitudinally, this medium is formed by particulate matter, particulate matter cooperatively interacts and limits the space to help heat transfer fluid flow flowing in the vertical between particulate matter, and these spaces mutually combine to limit vertical stream along the longitudinal axis that passes medium; Particulate matter and space can make fluid cross flow along the plane perpendicular to axis through medium, particulate matter is configured to limit the heat transfer between particulate matter and particulate matter, particulate matter is configured to promote the direct transmission of heat and fluid in the plane and attractive and therefore limit heat front (front) along the plane with the direct transmission of fluid to heat, its medium and fluid cooperate conducting heat between fluid and medium along this plane, thereby form perpendicular to this axis and along the heat front on this plane; Particulate matter stops heat transfer and attractive to flash heat transfer by directly contacting with fluid simultaneously by contacting with each other; And stream has and is used for the port that passes through for overheated working fluid, this stream this port have flowing stop after storage be in the zone of heat of the overheated working fluid of temperature T a.

Additional embodiments comprises stream controller, the flow rate of this controller control fluid, reach temperature T a along described plane when wherein flow rate is selected to and guarantees that particulate matter and fluid are in described plane, described stream has and is used for the port that passes through for the heated fluid that is in temperature T a, and the vapor phase of fluid is used as the working fluid in the system; Also comprise and be used to hold medium and have the transfer fluid cools port and the container of the overheated port of thermal fluid, described stream has superheat region and boiling range, in the zone of cooling port, this stream will be transported to boiling range as the fluid of the liquid that is lower than boiling temperature, this stream stores the heat as the fluid of the superheated vapor that is in temperature T a in overheated port zone, and this stream stores the heat as the fluid of boiling liquid in boiling range.In certain embodiments, described particulate matter also comprises heat storage material and thermoinsulation material, in stream, also comprise thermoinsulation material well-regulated (intermittently/interrupted, periodic) the porous heat insulation layer is to prevent in leading edge place temperature gradient owing to the transmission of heat of passing particulate matter reduces, wherein preferred heat insulation layer is channelled plate, this plate is made by thermoinsulation material, and can be the adiabatic layer of particulate matter that is similar to heat conducting material dimensionally.

In practice of the present invention, described stream has following ability: be stored in the heat of the steam that produces in the concentration solar generating unit, by supplying water to reservoir vessel this steam of regenerating, so that transmit the steam of regeneration when needed.In various embodiments, this comprises following ability: the heat that is stored in the steam that produces in the steam boiler of combined cycle generation unit when not needing steam to generate electricity, after this when needing, in independent turbine, use stored steam, thereby provide load-following capacity and storage to Combined Cycle Unit; Perhaps wherein additional steamturbine is greater than the steamturbine of unit itself and provide bigger short-term load-following capacity to be used for stablizing electrical network; Perhaps wherein this unit is that the integrated gasification combined cycle for power generation unit is to provide better load-following capacity to it; Perhaps wherein this unit is the coal-fired steam generator set; Perhaps wherein said stream has the ability of the heat that stores steam, wherein regains the steam that is used to store with reduction pressure from the outlet of the high-pressure turbine of steam electric power unit reheater after.

Be used for using the thermal fluid that is in about temperature T a or temperature T a that the another heat-storing method of stored heat is provided, this method may further comprise the steps: the ceramic heat-storage medium that the vertical section of prolongation with axis extension longitudinally is set, this medium is formed by particulate matter, particulate matter cooperatively interacts and limits the space to help heat transfer fluid flow flowing in the vertical between particulate matter, and these spaces mutually combine to limit vertical stream along the longitudinal axis that passes medium; Be arranged to make fluid cross to flow along plane particulate matter and space perpendicular to axis through medium, particulate matter is configured to limit the heat transfer between particulate matter and particulate matter, particulate matter is configured to promote the direct transmission of heat and fluid in the plane and attractive and therefore limit heat front along the plane with the direct transmission of fluid to heat, thereby its medium and fluid cooperate with the formation of conducting heat between fluid and medium along this plane perpendicular to this axis and along the heat front on this plane; Particulate matter is arranged to stop by contacting with each other simultaneously heat transfer and attractive to flash heat transfer by directly contacting with fluid; And stream be arranged to have be used for the port that passes through for overheated working fluid, this stream this port have be used for flowing stop after storage be in the zone of heat of the overheated working fluid of temperature T a.

Additional embodiments comprises stream controller, the flow rate of this controller control fluid, reach temperature T a along this plane when wherein this flow rate is selected to and guarantees that particulate matter and fluid are in the plane, described stream has and is used for the port that passes through for the heated fluid that is in temperature T a, and the vapor phase of fluid is used as the working fluid in the system; And comprise and be used to hold medium and have the transfer fluid cools port and the container of the overheated port of thermal fluid, described stream has superheat region and boiling range, in the zone of cooling port, this stream will be transported to boiling range as the fluid of the liquid that is lower than boiling temperature, this stream stores the heat as the fluid of the superheated vapor that is in temperature T a in the zone of overheated port, and this stream stores heat as the fluid of boiling liquid in boiling range.In various embodiments, particulate matter also comprises heat storage material and thermoinsulation material, and the well-regulated porous heat insulation layer that also comprises thermoinsulation material in described stream is to prevent in the leading edge temperature gradient owing to the transmission of heat by particulate matter reduces.In certain embodiments, heat insulation layer is the plate of tape channel, this plate by thermoinsulation material or the adiabatic particulate matter that is similar to Heat Conduction Material dimensionally make.

In a preferred embodiment, the heat reservoir that has the heat that is used to provide the storage that is in the thermal fluid X about temperature T a or temperature T a, this system comprises: have the container of transfer fluid cools input part and the overheated carry-out part of thermal fluid, this container has the vertical section that is communicated with input part and carry-out part; Ceramic heat-storage medium in vertical section, this medium has main longitudinal axis and time axis, this medium is formed and limits the space and flows and conduct heat to help fluid between particulate matter by particulate matter, the vertical stream of master that these spaces cooperatively interact and extend with the main axis that limits in the section longitudinally; Described stream is lower than the fluid stream of boiling temperature to seethe with excitement to the boiling range supply, described stream is overheated so that this stream is heated to superheat region supply boiling stream; And stream controller, this controller is set the flow rate of fluid stream, this flow rate realizes heating by a series of thin slices of boiling particulate matter in the boiling range and the overheated particulate matter in the superheat region, each particulate matter thin slice is limited at the cross section perpendicular to the inferior axis of main axis by particulate matter, this thin slice is heated and heats the stream of part amount, this part amount is seethed with excitement in boiling range and is superheated in superheat region about temperature T a or temperature T a, and the thermal fluid X that is in then about temperature T a or temperature T a is output at the overheated carry-out part of thermal fluid.

These and other embodiment comprises various power generation applications, industrial process etc., and in other is used, can be used to solar electrical energy generation unit, CCPP unit, ICGG unit, fire coal and combustion gas unit, nuclear power generation unit, geothermal power generation unit and other use the operation of superheated fluid work.

Description of drawings

Accompanying drawing illustrates embodiments of the invention and is used for explaining its principle.But be appreciated that accompanying drawing just for illustrative purpose designs, and be not as definition to boundary of the present invention.

Fig. 1 shows the common generator set that has according to heat reservoir of the present invention;

Fig. 2 shows exemplary reservoir vessel of the present invention in embodiment's the practice of Fig. 1 with the cross section;

Fig. 3-5 shows in different embodiments of the invention the contrast in the heat propagation of steam regeneration period, and wherein Fig. 3 shows use CO of the present invention ₂The heat front of heat transfer fluid system is propagated, and Fig. 4 of contrast shows H of the present invention ₂Heat front in the O system is propagated, and the two is all at 1500psi, and the H of the present invention that shows at 600psi of Fig. 5 of contrast ₂Heat front in the O system is propagated;

Fig. 6 shows heat reservoir according to the present invention as the application on the small-scale solar steam generator set of one of multiple application of the present invention.

Discuss various nonrestrictive exemplary and preferred embodiments of the present invention below.

Embodiment

Just for example and exemplarily discuss embodiments of the invention in the details shown in this, and in order to provide the description of be sure oing the most useful and easy understanding of principle of the present invention and notion aspect to propose.In this regard, do not attempt the level of detail more required for the present invention than basic comprehension and show CONSTRUCTED SPECIFICATION of the present invention in greater detail, the description of carrying out makes and those skilled in the art know that and implement several form of the present invention how in practice in conjunction with the accompanying drawings.

Unless otherwise noted, mentioning of compound or composition comprised this compound or composition itself, and combine, for example the mixture of compound with other compound or composition.Singulative " one " and " being somebody's turn to do " used in the literary composition comprise that also plural number refers to thing, unless context is clearly pointed out in addition.

The amount of all expression components of using in this specification and the claim unless otherwise noted,, reaction region etc. can be understood as is in all cases all modified by term " pact ".Therefore, unless point out on the contrary, the numerical parameter of the elaboration in following specification and the appended claims is can seek the desired character that obtains according to the present invention and the approximative value that changes.At least, and should not be considered as attempting to limit the application of doctrine of equivalents when explaining the right claimed range, each numerical parameter should make an explanation according to significance bit numeral and the common convention that rounds up.

In addition, the narration of number range is regarded as disclosing of all interior numerical value of this scope and scope in this specification.For example, if a certain scope is from about 1 to about 50, then think this scope for example comprise 1,7,34,46.1,23.7 or this scope in any other value or scope.But, in the claim not any scope of citation only be intended to describe rather than in order to limit the scope that the present invention is contained.

The invention provides and be used at system, the preferred method and apparatus of heat accumulation in the industrial system such as generator set.The present invention has overcome the heat accumulation restriction, and in fact, can be implemented in the exercisable in fact any temperature heat accumulation of most of generator set.The present invention is simple in design, and compares reliable more with other practical heat-storing method that is used for large-scale application and realize and operate relatively inexpensive.

The present invention can realize in various systems, and fluid particularly is provided and more specifically does the storage of the heat content of fluid for the thermal technology.In one embodiment, the thermal technology is the fluid that can be heated and can be used to the execution work function under its heated condition as fluid, and for example water is heated to produce steam and steam and is used to drive machines and does work, or is used for the purposes of the heat energy of other storage.

The present invention is deposited on the heat-storage medium in the container as thermal fluid and with the heat content of the vapor phase of this thermal fluid by using the thermal technology to make fluid, and Leng Que steam becomes liquid and removes from container then, provides the thermal technology to do the storage of the heat content of fluid.When needing the thermal technology to make fluid once more, a part of cold working fluid returns heat-storage medium and hot again its vapor phase of one-tenth of quilt as thermal fluid, takes out to make fluid as the thermal technology from container then.Here do not need boiler, because the hot again boiler that has replaced utilizing stored energy.

In a preferred embodiment, the present invention is deposited on the heat-storage medium in the container as thermal fluid and with the heat content of this thermal fluid by utilizing the thermal technology can experience phase transformation to make fluid, and remove the fluid of whole cooling from container at fluid when filling (charge) direction is flowed through storage medium then, provide the thermal technology to do the storage of the heat content of fluid.When needing the thermal technology to make fluid once more, a part of working fluid returns heat-storage medium as thermal fluid, preferably with the convection current of filling direction, and by hot again, take out and returns work system and make fluid to be used as the thermal technology from container then.

In preferred practice of the present invention, use and the working fluid of the vapor phase by being in its heating carries out work or from this phase store heat, the fluid that utilizes the same type that at first is in liquid phase then is as thermal fluid and utilize the fluid that is in vapor phase and returns to reclaim heat as working fluid then.More preferably, the present invention uses vapor working fluid and steam thermal fluid, most preferably overheated steam under pressure.

Steam most important use in generator set is a superheated vapor, and its free energy depends on the temperature of steam to a great extent.The present invention can with＞90% and perhaps even＞operation of 95% the thermal efficiency.The efficient ability that stores the heat content of steam has produced the technical opportunities of extensive use in a lot of fields, for example be used to enlarge the capacity of generator set, provide and to assign energy, provide better control function to regulate to generator set, and be used for other heat of using storage or the industrial purposes of steam to carry out electrical network.

Storage electric power has become the main demand under the current environment.Because most of generator set relate to steam, " storage " is used for the equivalent of the electric power of generator set so the present invention described herein is by the heat content that stores steam.It is that cost is effective that this innovation is compared with other method extensive at this type of, that the commercial size amount stores electric power.

In one embodiment of the invention, thermal source (for example, boiler) produces and be used for the steam that does work in the work loop, for example in the work loop steam driven steamturbine with generating.When this working fluid, preferred superheated vapor can be when storing circulation institute and utilizing, promptly, in the time can obtaining to surpass the capacity of demand, usually in the off peak hours section, overheated working fluid steam is sent to the store loop that comprises storage medium from the work loop, and this moment, this fluid was as the thermal fluid that steam heat is carried into storage medium---heat is passed to storage medium from thermal fluid steam, and wherein vapor condensation and condensation product liquid water are discharged from storage medium.Heat is stored as required and is fetched when needed.When needs when storage medium is fetched steam, water by with line transportation to the storage medium that has heated, and steam is reproduced then and returns the work loop as the thermal technology as fluid.Preferably, work loop and store loop are connected to each other realizing closed loop with suitable valve, thus preservation fluid (water).

In a preferred embodiment, the heat content that the present invention includes steam is deposited on the solid material, this solid material preferably has high heat capacity and high thermoconductivity, for example be the aluminium oxide cobble, the mode of deposition be we preferably by supplying with water through storage medium convection current ground at the perhaps low slightly pressure steam of regenerating at original temperature or about original temperature.With regard to efficient, this is equivalent to directly store steam.

Store the heat content of steam and provide second turbine to utilize stored heat, can help to satisfy the national energy demand to a great extent to generator set.In addition, the storage of steam enthalpy can help to provide rational adjusting ratio and can improve load-following capacity in combined cycle generation unit (CCPP).In CCPP, the steam electric power unit generally provides about 40%-45% of unit total electricity output, and gas turbine can be all the time operated under boiler is in the state of maximum capacity, simultaneously the steam of any surplus is transferred to storage device thereby allow that second (steam) turbine is carried out Steam Generator in Load Follow.By the steam driven of this storage, this has increased CCPP in the total capacity of peak load or at others control power network fluctuation to auxiliary turbine when needed.For usual steam electric power unit, problem is under any circumstance, to be used for certain purpose if store the heat content of steam, if more cheap than increase capacity, its objective is in most of the cases that then extra source that this energy stored is provided and its are more cheap such as it.

For the concentration solar generating unit, it is valuable selection that steam heat stores, and has particularly had the trap of direct generation steam.When needed, for example, when such as solar energy at night when not enough, steam is reproduced.Under custom-sized situation suitably, the solar electrical energy generation unit can 24/7 operation, and can be used to by using this stocking system to control power network fluctuation.

As mentioned above, embodiment as herein described illustrates by way of example and unrestricted mode provides, and is not the storage that intention is limited to scope of the present invention or its application the heat content of hot steam.Therefore, described in the content, the storage of the heat content of steam comprises the notion of utilizing any condensable steam as disclosed herein, and comprises any two phase system with a high-temperature vapour phase and a colder liquid phase.This optimum system choosing is operated in two-phase, and replaces water, also can use propane, butane and other condensable gas.

In a preferred embodiment of the invention, convection type cobble bed heat exchanger possesses storing function, and wherein heat exchanges in acyclic mode, that is, heat is stored and can utilizes when needing afterwards.Heat steam preferably enters reservoir vessel at the top of vertically-oriented container along a direct of travel, and add heat-storing medium (preferably ceramic particulate matter), and preferably, the bottom keeps cooling so that can discharge heat energy necessarily---otherwise will reduce efficiency of storage.Pipeline and medium and flow and to be designed such that hotwork is that apparent in view leading edge is advanced by reservoir vessel.When further loading will be discharged steam or boiling water, reach capacity.When fetching when hot, cooling water flows into exhaust end to form and to transmit the regeneration steam of fetching and return work system from the top of container, i.e. steam along opposite flow direction.

In a preferred embodiment, in order to ensure tangible leading edge, the fluid that heats (or cooling) enough flows lentamente, make its temperature reach and the storage medium complete equilibrium in very short distance (comparing) with the total length of exchanger, most preferably at the coefficient that surpasses 1 to 100 (distance and total length), or preferred at least 1 to 10 coefficient, but to obtain high efficiency, this coefficient should be big more a lot of than 10.

Compare very short the heating time that this particulate matter that requires heat-storage medium is cobble or stone with the waiting time of steam.In this case, for the given shape of particulate matter, heating time and r ²/ α is directly proportional, and wherein " α " is that pyroconductivity and " r " of medium are the characteristic lengths of selected packing material.Therefore the more small particle that preferably has high thermoconductivity.It will be understood by those skilled in the art that this of control or restriction load for heat heating time and the heat recovery desirable top speed that given reservoir vessel is allowed for the two.

The invention provides can be with high efficiency heat reservoir with retrieval mode heat energy storage in various application.This heat reservoir can be fit to use for various power sources such as steam power source.Embodiments of the invention are taught in and comprise concentration solar generating unit, steam electric power unit, coal fired power generation unit, combined cycle generation unit, the storage of heat in the various application of solar electrical energy generation unit and in other purposes on a small scale.

Fig. 1 shows the exemplary power generation system 10 that comprises generator set 10A and heat reservoir 10B according to of the present invention, wherein generator set 10A produces hot fluid 11, and this hot fluid is used in this unit acting or can be used for thermmal storage neutralized to heat reservoir 10B and fetch heat from heat reservoir 10B.Also by using fluid 11, the heat that is stored among the stocking system 10B is returned unit 10A frequently additionally to do work at this unit.

In practice, the hot fluid that produces in the boiler 12 (for example, superheated vapor) 11 are used as the working fluid 11a that is used to drive turbine 13, or alternately, and this superheated vapor is shifted from turbine 13 at valve 14 places and is used as thermal fluid 11b the heat reservoir 10B.

Hot fluid/superheated vapor 11 enters heat reservoir 10B as thermal fluid 11a via the input part 15 of reservoir vessel 16, and flow through and heating container in heat-storage medium 18.The heat of this storage is fetched from storage medium 18 later when needed, the superheated vapor 11 that is back to unit 10B and uses at unit 10B with regeneration.

With reference to figure 2, preferably, reservoir vessel 16 vertically-oriented one-tenth make that superheated vapor 11a is used to fill heat and arrive downwards on the route of bottom 39 of container 16 at the storage medium 18 of flowing through of the filling direction of axis I-II longitudinally at it from 38 pairs of storage mediums in top of

container

16, and 39 condensed waters 20 are moved to storage tank 22 in the bottom.Water 20 remains in this jar, then when needed from storage tank 22 be back to boiler 12 in case again heat or convective flow, be redirected to container 16 with regeneration superheated vapor 11.

When need be from the superheated vapor of stocking system 10B, preferred water 20 is pumped to the inlet 25 of vertical container 16 from jar 22, with regeneration superheated vapor 11, superheated vapor 11 is via being back to unit 10A to drive turbine 13 in outlet 28 outputs at the top 38 of container 16 and as working fluid 11a along top 38 that axis I-II upwards arrives containers 16 by the storage medium 18 that has heated.Like this, there is not big quantity of fluid in fact in the heat accumulation state, that is, be stored in the container 16 from heat rather than a large amount of fluids of superheated vapor, and a certain amount of then colder liquid 20 is only guided when needs steam is regenerated again.

In preferred practice of the present invention, container 16 be vertical and superheated vapor 11 at container top 38 storage medium 18 that is directed and passes through, make at least during fetching heat propagate so that the heat transfer efficiency maximization along apparent in view leading edge, wherein container top 38 is in maximum heat and the end that leaves in the bottom 39 of container keeps colder in the temperature of the steam 11 of input.Keep colder end for the purpose of efficient, make boiling water can not flow out to jars 22 from reservoir vessel---wherein the heat of water will be wasted.Make under the maximized situation of efficiency of storage in hope and not do like this.

In preferred practice of the present invention, a part of storage medium is heated to very high temperature when being provided the thermal fluid of arrival.Between payoff period, flow rate is controlled such that heat in apparent in view leading edge propagation, thereby the maximum temperature that allows to be stored in heat reclaims stored heat, and this heat is preferably from superheated vapor.Be understandable that: if leading edge moves too fastly between payoff period, then total reservoir vessel will be cooled off almost evenly, and the temperature of the steam that is reclaimed will drop to mean temperature continuously.The total amount of heat that reclaims will keep constant, but only a part of steam will be recovered in head temperature, cause free energy to lose in a large number.This is avoided in practice of the present invention, because seek to reclaim the highest storage temperature, rather than average storage temperature.

In one example, hot fluid 11 is to be in the overheated gas steam of initial temperature and to flow through container 16 till medium 18 is heated to this temperature.When steam when the medium, the steam cooling and therefore steam leave container in lower temperature, and container end portion 24 is in this lower temperature.When lower temperature began to rise, stowing operation stopped.But, most preferably keep in the hot junction temperature as far as possible near and even keep constant at the top, to keep high thermal efficiency.Temperature at cold junction is so unimportant in the hot junction near control.

More specifically, superheated vapor thermal fluid 11a is directed from the top 38 of container 16 and when it continues to flow regional 18a is heated to temperature T a, having discharged enough energy up to fluid makes and its experience phase transformation and be condensed into boiling water then the storage medium among the regional 18b is heated to boiling temperature Tb.The thermal fluid 11a of condensation continues the medium among the regional 18b is heated to boiling temperature when it flows to container bottom 39, and after this, the thermal fluid 11a that is in the further cooling of temperature T d this moment arrives the regional 18c be in container 16 ends---the boiling temperature that wherein remaining enough heat energy reaches storage medium to be used to store, and therefore thermal fluid is discharged to jars 22 as the discharge fluid 20 that is in the cooling of temperature T d.Again,, wish at the filling heating of medium storage medium 18 as much as possible and steam is not discharged from container, and therefore to discharge fluid 20 in this case will be the water that is lower than boiling point in outlet 21 for the purpose of efficient.

Those skilled in the art can understand now, can by the temperature of monitoring discharge water 20 and when temperature begins to rise or becomes too high, stop to flow and preferably far below boiling point (, boiling point far below the water that is in pressure store) stops the time, come control heat reservoir 10B during filling.Flow rate be preferably selected to make to obtain that heat transfer as much as possible and the preferred bigger overheated zone 18a of construction make when steam is regenerated can be at the superheat temperature Ta more substantial steam of regenerating, the flow rate that is used to regenerate is selected to the transmission maximization that makes as from the superheated vapor of the working fluid that comes out in the outlet 28 at container 16 tops, and being flowing in when temperature no longer is in preferred temperature as working fluid 11a of the superheated vapor of regeneration stops, unless wish extra heat again.

From Fig. 2 as seen, in one example, the thermal fluid 11a of heat is in the superheated vapour of initial temperature Ta and the container 16 of flowing through, and is heated to this superheat temperature Ta up to the first area of medium 18 18a.When fluid process medium, the fluid cooling also becomes boiling water in the second area 18b of the medium that is being in temperature T b, and in the 3rd regional 18c, reach the lower temperature Tc that is lower than boiling point at container bottom 39, and after this leave container in outlet 21 at temperature T c.In one embodiment, flow rate meets the demands, wherein most of medium 18 be heated to superheat temperature Ta and only the fraction zone be in boiling point, the end is lower than boiling point then.

Heat levels can detect by the outlet temperature Td of monitoring fluid stream, and when outlet temperature reached " stopping " temperature of appointment, then fluid is mobile stopped with stowing operation.Preferably, this stop temperature near but be lower than boiling temperature Tb so that via the further minimum heat losses of the hot fluid that leaves container, because thermal loss can influence overall system efficiency.

In optional practice of the present invention, the superheated vapor 11 that the is in temperature T a entire path I-II in the container that flows through, and only flow and to be in during at the steam flow container or to stop during near initial temperature Ta at outlet temperature Td.This can realize the maximum storage utilization of container 16 but lost the entrained heat energy of steam that flows out in stowing operation, therefore not do like this when efficient is most important.

Be understandable that: in the solar electrical energy generation embodiment of the invention of Fig. 1, boiler 12 be solar energy heating and provide superheated vapor 11 to drive turbine 13 or to be re-directed to storage device 10B as mentioned above.In this case, come the superheated vapor 11 of the regeneration of self-storing mechanism 10B to drive existing turbine 13 so that extra electric power output 30 to be provided at night.In the fuel type generator set embodiment of routine of the present invention, therefore turbine 13 guides the steam of being fetched 11 to drive auxiliary turbine 32 usually in the peak value production operation when needed, exports 30 to supply extra electric power, thereby increases the output of turbine 13.

In a preferred embodiment, storage medium 18 has high heat capacity to minimize storage volume, uses obtainable, well-known material such as passing through, and this material can be mass-produced to reduce cost.In a preferred embodiment, heat-storage medium 18 forms the bed 19 of alumina material part 19 ', for example stone, cobble or ball ball, and steam 11 longshore current road I-II (in Fig. 2 for the vertical) medium 18 of passing through flows between material part 19 '.

Be understandable that: when storing superheated vapor hot, will have superheat region 18a and boiling range 18b, be short in cool region 18c then.In practice, " significantly " leading edge between the heat of the heat of hope maintenance superheat region 18a and boiling range 18b." significantly " leading edge is meant that superheat region is heated best and separates with boiling range, and borderline phase should move in company with flowing.Significantly leading edge is optional in the filling circulation, but in regenerative cycle very preferably.Fluid flows through container perpendicular to the cross section, and purpose is to obtain the complete temperature equalization in short distance (that is, longshore current way foot) between steam and the storage medium, and as tangible leading edge, we are defined as plane P perpendicular to longitudinal axis with it.In a non-limiting example, significantly long 30 ' transition region 18b is relevant on leading edge and 140 ' the storage path.Plane P is illustrated as overlapping and should be understood that in this embodiment to drift moving in company with fluid along the flow axes that is parallel to plate 40 in fact with boiling range 18b in Fig. 2.

Select preferred storage medium, alumina particle thing (for example, stone or cobble) is because the heat transmission resistance in the vapour system is low.The latter means that the pyroconductivity height and their size of aluminium oxide is little, and it is very short to make the required time of temperature that reaches flow of heated fluid compare with the fluid waiting time, and the temperature of aluminium oxide so the in fact instantaneous temperature of hot fluid on every side of following.

One decision design allows filling downward from the top and the counter that makes progress from the bottom, preferred laterally have the uniform distributions of making peace through diameter, on the very short fluid along flow axes I-II flows distance (for example, 140 ' 30 '), reach and conduct heat completely and the temperature equalization.This system comprises solid filler, for example, can realize having the high density ceramic particulate matter in the design of fluid stream of low pressure loss.The pyroconductivity of stuffing should height and heating time of stuffing should be short as far as possible, but too small particulate matter can cause the excessive pressure drops in the process fluid flow.Even so, for the latter, the low pressure loss in the reservoir vessel is not crucial for steam stores, and does not compress again because do not need.Can use and satisfy basic design concept as herein described and allow to store such as any design with high thermal efficiency (preferably utilizing convective flow) from the heat of steam of steam.The size and the structure that it will be understood by those skilled in the art that particulate matter will be trading off between acceptable heating time and the acceptable pressure drop.In addition, when storage medium such as ceramic cobble are exposed to the temperature, pressure of variation and condition, select this material to make it can tolerate these conditions, and preferably have low porosity () material roughly＜5%.

In addition, in a preferred embodiment, in order to prevent particularly when having temperature gradient in the bed in storage process heat transfer by particulate matter, so that can in bed, slowly be heated to very high temperature, we preferably in the cobble bed compartment of terrain adiabatic porous slab is set, the hole is enough little of to keep packing material.It will be understood by those skilled in the art that in a preferred embodiment we stipulate that the heating time of solid particulate matter is short.

Be understandable that: operation is preferred and useful for peak efficiency in allowing the efficient condition window that stores, therefore, the mode of supplying with the speed of the superheated vapor be used for regenerating or water should be to make heat particularly significantly propagate in the leading edge in callback course.

Fig. 2 has illustrated the module that assembles in the lateral section, loaded cobble bed 19 and filled internal tank from container top to container bottom, and stream I-II extends through medium 18 between the cobble material 19 ' of cobble bed 19.In practice of the present invention, but single big reservoir vessel 16 used, although preferably assemble less module to form container.Single this module (such as the long pipe section of 20-30 foot) is fit to form the small power generation unit, and can assemble a plurality of containers for more large-scale unit.For example, can stacked seven 20 feet long modules have 140 feet reservoir vessels of end cap (that is manifold) with formation.

Referring again to Fig. 2, in illustrative practice of the present invention, reservoir vessel 16 preferably includes cylindrical shape module 16A, two module 16A1 and 16A2 by vertical stacked and container 16 sealing be by on the corresponding outer end of module 16A1 and 16A2 respectively at the top 38 of container 16 with manifold plate 16B1 is set up in bottom 39 and 16B2 forms.In addition, each module 16A is provided with flange 41 and makes that the modules of coupling can be sealed together to form sealed department 43, as shown in the figure in the adjacent ribs of converging 41 in its top and bottom.The top that manifold plate 16B1 is set at module 16A1 makes manifold plate edge 45 cooperate to form sealed department 47 herein with adjacent flange 41, and the bottom that manifold plate 16B2 is set at module 16A2 makes panel edges 45 cooperate to form sealed department 49 with adjacent flange 41, thereby provide the reservoir vessel 16 of sealing, as shown in Figure 2.

Cylindrical shape module 16A, the 16B of Fig. 2 preferably use the section of ready-made large diameter steel pipe such as the steel pipe that is used for natural gas line, each section is cut into and is easy to the length (such as the long section of 20-30 foot) of transporting and assembling, and is equiped with flange to assist the assembled on site container.These modules 16A, 16B etc. preferably have been assembled perforated plate 40 (Fig. 2), and its hole 44 is in the appropriate location less than the diameter of storage material 19 ' to keep storage material.It will be understood by those skilled in the art that these plates 40 are also as the fluidic distributor with routine of expecting pressure drop.What will be further understood that is: these plates are preferably made to minimize the transmission of heat by storage material by thermal conductive ceramic not, be limited to direct contact the between fluid 11a and the cobble material 19 ' ideally because conduct heat, and because the balance between heat and the colder storage section can reduce and can be reproduced and from the amount of the maximum temperature superheated vapor of stocking system transmission.Wish the transmission of heat between the restriction particulate matter, therefore in a practice of the present invention, we are provided with adiabatic step, and such as isolated plate 40, it is mobile and enough little of particulate matter is remained on the appropriate location to allow fluid that these plates have enough porosity ratios.

Like this, heat can be preserved for a long time at the section of each filling.This set also helps by separable section between the hot-zone section of storage element wherein and the cold-zone section and helps partially recycled section, such as when the heat of carrying out some storages partially recycled.In one embodiment, also be provided with other port 46, be used to the fluid input that stores or reclaim or extract fluid out so that carry out monitoring temperature etc. such as being used to increase to help partially recycled or other optional fluid stream.

It is the bead of the non-porous aluminas of 1-10mm (preferred 2-3mm) that an example of the ceramic filling material of recommending 19 ' is to use diameter, and the result of expectation is the rapid heating medium.

The structure of modular container and joint supply pipeline forms firm structure, and wherein flanged pipeline section is strengthened the intensity of independent pipeline to form the high-strength structure that can be anchored into ground.Usually, up to for the pipeline of about 5 ft diams, can utilize pipe section for size.This design has been avoided on-the-spot formation and can have been transported in truck.These pipeline sections should be designed to assemble at the scene easily.For this reason, these pipeline sections should enough be lacked, and make them can form and fill commercially available pottery, and intactly transport so that finally assemble at any time.This is more cheap than building large-scale reservoir vessel at the scene.

In one embodiment, storage medium is applicable to wide temperature range, preferably from ambient temperature to more than the required maximum temperature of specific generation technology.This temperature is about 1350 ℉ for the high-efficiency steam generator set, and is 2200-2500 ℉ for gas turbine.Attainable maximum temperature has also determined storage cost.In fact, though high temperature may require more expensive material, required storage volume and therefore the cost of system and the head temperature of power generation cycle and the difference of bottom temp be inversely proportional to, in generator set.

Be understandable that now: store in the mode of execution at steam of the present invention, use the vapor phase and the liquid phase of identical formation fluid (that is water).This advantageously can make identical fluid be interchangeably working fluid be again thermal fluid, this allows work system very economical.Therefore, in practice of the present invention, storage medium 18 is filled with preferably from the heat of overheated steam under pressure 11, and the heat in the storage medium 18 keeps being stored then, till the fetching as requested of the colder water 20 of later use.Therefore, the working fluid of system (for example, steam) also is the thermal fluid (for example, steam) that is used in the downstream use, generates electricity such as being used to drive steamturbine 13.

Utilize water/steam to have the advantage of high heat transfer coefficient as thermal fluid.Up to now also not to the practical storage of superheated vapor.But in the present invention, in a preferred embodiment, used superheated vapor, preferably filled reservoir vessel as mentioned above from the top downwards.After, can reclaim heat by at the bottom feeding cold water, leave with convection type regeneration and from the top as the superheated vapor that in fact is in the temperature and pressure identical with storage at first.Preferable process of the present invention is: supply overheated gas steam (for example, steam) 11, with thermmal storage (for example at condensing steam, steam) in the medium 18 and then (for example with condensed fluid 20, water) be expelled to jar 22, wait demand, and the gas vapor (for example, steam) 11 of regeneration heating after cooling liquid 20 being directed to again in the container.

Preferably, superheated vapor input part 15 and regeneration steam carry-out part 28 are positioned at storage medium 18 tops at the top 38 that is in container 16, and liquid carry-out part 21 and input part 25 are positioned at the storage medium below of the bottom 39 that is in container 16.Like this, storage medium 18 and fluid stream are vertically-oriented in container 16, fall towards outlet after heat transfer and phase transformation such as being contained in steam of introducing at the top 11 and the liquid that allows condensation, and will after colder liquid 20 is introduced into, hold steam at the steam regeneration period and rise.This set helps the regeneration of superheated vapor 11.

What will be further understood that is: in fact input part 15 on the container top and carry-out part 28 can be the single bidirectional ports that possesses corresponding described entrance and exit function in time, and the outlet 21 and the inlet 25 that are in container bottom can be another the single two-way valve that possesses corresponding described function equally.Under any circumstance, preferably these ports during the filling storage medium and regeneration the time open and between the storage life, close.

In addition, in a preferred embodiment, in order to prevent between the long-term storage life particularly when having temperature gradient in the bed heat transfer by particulate matter, so that can in bed, slowly be heated to very high temperature, we preferably in the cobble bed compartment of terrain adiabatic porous slab or porous mass are set, the hole is enough little to keep stupalith 19 ' simultaneously to allow that fluid flows.

For many application, particularly be used for the small-scale unit of distribute energy---it can not utilize the turbine that has again the hot merit energy---, steam is that favourable thermal fluid is selected.For the generator set (for example, gas turbine, Stirling (Stirling) motor or similar device) of using gases, the invention enables and to use the gas identical as thermal fluid with the gas that is used as working fluid as driving fluid.

Can further be understood that: at H ₂Do not need to be used for again the boiler that the thermal technology makes fluid in the O system; The reservoir vessel 16 that is filled with is boilers.At preferred CO of the present invention ₂In the mode of execution, the overheated CO of regeneration ₂To be transferred into boiler to produce steam, this steam will drive steamturbine again.

Fig. 3-5 provides the contrast of heat propagation in different embodiments of the invention.Fig. 3 shows and utilizes CO ₂The heat front of heat transfer fluid system is propagated, and shows when pressure is 1500psi during heat recovery the diagram of advancing of heat front in container.

It is that 1500psi and temperature are when being 1200 ℉, at H of the present invention that Fig. 4 shows during heat recovery pressure ₂The heat front of superheated vapor is propagated in the O system.It will be understood by those skilled in the art that in constant compression force overheated big more, leading edge is just precipitous more, and leading edge is precipitous more, it is just effective more to conduct heat.In the process that stores steam heat, finish identical " constriction (pinch) " (at " Z " locate) of overheated recovered steam of use to avoid causing by phase transformation at the lower pressure of embodiment's utilization.As long as it is constant that final vapor (steam) temperature keeps, it is just little to the influence of efficient to reduce pressure.Can see referring to Fig. 4, when leading edge is advanced, exist constantly to increase but short flat temperature leading edge section.As long as keep this situation in the complete heated section, steam will be by overheated.Diagram among Fig. 4 and Fig. 5 just schematically and be based on the such hypothesis of temperature constant in the whole bed.It will be understood by those skilled in the art that in actual cycle, temperature profile is more complex, but the feature class of temperature leading edge is similar to shown in Fig. 4 and Fig. 5 those.

Those skilled in the art can further understand, and this short section that is in steady temperature can cause storing " constriction " in the circulation.A kind of mode that overcomes this pinch effect is to carry out the recovery circulation at lower pressure to make straight section be lower than the boiling point of the steam that is used to store.This is shown in Figure 5, and by pressure being reduced to 600psi (or even 400psi), the temperature of this flat region Z significantly is reduced to below the boiling point of the fresh steam that enters storage device.Finish owing to store not being lower than boiling point, so constriction is unimportant.

If short in the flat region that stores the circulation end, then there is the optional mode that overcomes constriction, that is, and by supplying heat only to use the overheated constriction that overcomes in this flat region of extra steam.The extra heat of the water of condensation and cooling condensation will cause temperature higher in the section of cold-zone.This is useful in short-term when straight section.This two kinds of method combinations when needed and optimization.In most of the cases, preferred first method.What allow that we reduce pressure is: constant overheated, pressure is little to the influence of free energy.

The formation of heat front takes place due to the fact that between payoff period: the gradient of heat rate is owing to the fact that occurs in steady temperature becomes level or interruption.In one embodiment, we reduce pressure to adapt to this situation.As shown in Figure 5, by pressure being reduced to 600psi (or even 400psi), the temperature of this flat region Z significantly is reduced to below the boiling point of the fresh steam that enters storage device.Alternately, more steaminess is supplied to storage device, and its heat is along with hot water is recovered near boiling point.For high efficiency more, can with hot water supply to trap or boiler to increase heat and to keep system effectiveness.This two kinds of method combinations when needed and optimization.In most of the cases, preferred first method.What allow that we reduce pressure is: constant overheated, pressure is little to the influence of free energy.

In addition, in a preferred embodiment, in order to prevent that heat transfer by particulate matter is so that can slowly be heated to very high temperature in bed, we preferably cobble bed internal layout adiabatic porous slab is set, the hole is enough little of to keep packing material, or alternately, we can use the thin layer of the size adiabatic particulate matter identical with the storage granules thing.

The temperature and pressure that can be stored steam does not carry out physical restriction.Problem is cost.Along with pressure rises to 1800psi, the cost of container begins rapid rising.In our decision design, as long as pressure is lower than for example 1200psi, pressure is just very little to the influence of cost, or even still little in the 1500psi influence.If desired, and to have proved higher cost be reasonably, then reservoir vessel can be designed for higher pressure.

Same situation is applied to temperature.Storage means itself is temperature limitation not, and more than 1100 or 1150 ℉, container and pipeline should be by making at the stainless steel that uses up to 1500 ℉, although seldom there is the application that need store steam in the temperature that is higher than 1400 ℉ in practice.But, make container with internal insulation and do not carry out then and external insulation by using ceramic coating, can be at higher temperature use standard steel vessel.

In preferred practice of the present invention, heat is propagated with maximum heat transfer along apparent in view leading edge, and wherein, by stopping before arriving outlet at heat front or reverse circulation, the heat outlet always keeps hot and cold outlet maintenance cold.It is most preferred that: the hot junction of reservoir vessel always remains on the maximum temperature of steam or steam to be stored.Therefore, though the variable temperatures in hot junction, the hot junction of preferred reservoir vessel remains on the temperature of substantial constant.Cold junction only need be in the temperature of the boiling point that is lower than the steam that is used for filling or steam.Therefore, the variable temperatures of cold junction and need not preferably remain on the temperature of substantial constant.

Be understandable that: the present invention has utilized the principle of recuperator in the cyclic process of heat and exchange, and this recuperator has been used for by making hot waste gas and the fresh air that is supplied to burner carry out the thermal efficiency that heat exchange improves generator set in the past.In the exploitation of circulation catalytic reactor, used recently identical principle.Usually, for recuperator and circulation catalytic reactor, cycle alternation and endurance equate, and gas velocity also equates on both direction.

The present invention includes this understanding: can make amendment so that the power generation values of increase to be provided to these recycle heat exchangers, wherein the thermmal storage that is filled in of storage medium is interrupted afterwards, and the storage medium store heat is till it needs.According to the capacity of stocking system, this can be used for the time period of any reality.

It will be understood by those skilled in the art that in order to generate tangible leading edge, on cross section, make and supply with evenly perpendicular to the flow direction by medium.In a preferred embodiment, we use has the fluidic distributor of pressure drop and heat transmission resistance that we require storage device is enough low and the enough height and their size is enough little of the pyroconductivity of cobble, therefore the required time of temperature that reaches air-flow compare with gas residence time can accept short or even very short, and the temperature of particulate matter is therefore in fact even instantaneous temperature of following surrounding fluid.

In a preferred embodiment, storage medium is applicable to wide temperature range, preferably from ambient temperature to more than the required maximum temperature of specific generation technology.This temperature is about 1350 ℉ for the high-efficiency steam generator set, and is 2200-2500 ℉ for gas turbine.Attainable maximum temperature has also determined storage cost.In fact, though high temperature may require more expensive material, required storage volume and therefore the cost of system and the head temperature of power generation cycle and the difference of bottom temp be inversely proportional to, in generator set.

In a preferred embodiment, storage medium has high heat capacity minimizing storage volume, and preferably uses obtainable, well-known material, and this material can be mass-produced to reduce cost.In a preferred embodiment, heat-storage medium uses little alumina balls ball.

Utilize water/steam to have the advantage of high heat transfer coefficient as thermal fluid.Up to now also not to the practical storage of superheated vapor.But in the present invention, even can use superheated vapor, preferably fill reservoir vessel as mentioned above from the top downwards.After, can by at the bottom feeding cold water, with convection type regeneration, and leave from the top as the superheated vapor that in fact is in the temperature and pressure identical with storage at first, reclaim heat.

H when Fig. 5 shows pressure and is 600psi ₂Heat front in the O system is propagated.By pressure being reduced to 600psi (or even 400psi), the temperature of this flat region Z is significantly reduced to below the boiling point of the fresh steam that enters storage device.Alternately, when pinch area hour, we can only supply with storage device, and more steaminess is as the hot water near boiling point, and the heat of steam will be recovered.Hot water can be supplied to trap or boiler, and the flow that has increased them makes not can lost heat, because use identical heat input to produce more steaminess.These two kinds of methods can be when needed in conjunction with also optimizing.In most of the cases, preferred first method.What allow that we reduce pressure is: constant overheated, pressure is little to the influence of free energy.

Temperature and pressure in the time of can being stored steam does not have physical restriction.Problem is cost.Along with pressure rises to more than the 1800psi, the cost of container begins rapid rising.In our decision design, if pressure be lower than for example 1200psi or even 1500psi---wherein effect is still little, pressure is just very little to the influence of cost.If desired, and to have proved higher cost be reasonably, then reservoir vessel can be designed for higher pressure.

Same situation is applied to temperature.Storage means itself is temperature limitation not, and more than 1100 or 1150 ℉, container and pipeline should be by making at the stainless steel that uses up to 1500 ℉, although seldom there is the application that need store steam in the temperature that is higher than 1400 ℉ in practice.But, make them with internal insulation and do not wish then and external insulation by using ceramic coating, can be at higher temperature use standard steel vessel.

The length of each container and the quantity of required container depend on specific design.Actual design depends on load pattern and physical constraint, and preferably by guaranteeing that heat front under all conditions all keeps enough obviously the head temperature when guaranteeing that the steam that heats leaves reservoir vessel to remain at expected value and guide design.

Steam stores some exemplary application of invention:

Concentration solar generating unit (CSP):

Most of CSP unit that is moving at present, and the CSP unit of developing use the steam that produces in boiler as working fluid, if exist simultaneously, they use another kind of thermal fluid in trap and storage device.But, exist and use the CSP unit of steam as the thermal fluid operation.We believe, boiled water/vapour system heat transmission function that can offer the best.

A known example is to utilize the boiling water that stores pressurization in container and pass through to reduce pressure to produce the solar column of the short term stored method of steam in 600 ℉ operation.The efficient of this way is not high.The temperature of 1200 ℉ produces steam to use for example but can easily revise this tower in practice of the present invention, and superheated vapor is better than saturated vapour greatly aspect the thermal efficiency.

Can utilize to have and produce the slot type trap of the live steam generation of superheated vapor at 1050 ℉ or higher temperature.But these traps lack storage device at present.In practice of the present invention, we provide efficient very high storage device, with at identical pressure and overheated, or in some cases at identical overheated but lower pressure, regain accurately identical steam.This has increased the Δ T of storage device and has therefore reduced the size of reservoir vessel and their cost.

Steam is better than being used as respectively at present the dowtherm (Dowtherm) and the fused salt of thermal fluid and storage medium greatly, because it does not have temperature limitation.It does not need heat exchanger or boiler yet.Equally, H ₂The O system can be by most economical ground not only as working fluid but also as thermal fluid.

Vapour system of the present invention need not boiler, therefore the temperature loss that does not exist heat exchanger to cause.Simplicity of design and do not need compressor; Pressure drop in pipeline or the trap has slight influence, because constant overheated and not have under the hot again situation, efficient only is the minorant of pressure.

Solar electrical energy generation unit with live steam is favourable for multiple use.Have under the situation of live steam, need not to compress again any gas or long distance pumping thermal fluid, the two all needs the power consumption derived from.In the live steam that does not carry out again heat uses, still realized higher temperature and need not to conduct heat.Higher temperature adds and does not have the derivation loss, has compensated a large portion of the difference of heat again of efficient and increase.

An advantageous applications of live steam is to be used for Small-sized C P unit, for example is lower than 100MW, and is low to moderate the perhaps more small-sized distribution type CSP unit of 50kW especially for specification.These are useful for remote districts.

Generator set has significant size factor.Have certain efficient and pollute the conventional coal fired power generation unit of the 10MW that controls expensive more about more than three times than the every kWh of 200MW unit that is used for the same terms.

Size is much smaller for the CSP unit with live steam storage device for the influence of cost.The CSP trap and the reservoir vessel that are used for our method are the modular assemblies of preferably producing and be sized to easy transportation in enormous quantities.In example system, what we needed is nothing but enough traps, reservoir vessel, pump and the turbine that links together, and size impact is only relevant with pump with a fraction of turbine of the overall cost that accounts for CSP.In this case, the simplicity with CSP of live steam storage device makes it be better than the CSP or the solar energy of coal or other type greatly for small-sized unit.

The solar energy live steam stores second kind of application with decisive advantage and is used to the steam that is used for large chemical plant and refinery and electric power coproduction or carries out the CSP unit that heavy oil reclaims or the extensive steam generation of similar applications designs in the area with sufficient sunlight for being used for.In all these were used, must carry out comparable any other CSP design of operation in 24 hours and storage means of the present invention provided this point more cheaply.

For all these application, superheated vapor is preferred, and its storage owing to low-temperature saturated steam is feasible and important according to the present invention, but will be expensive more.Should be at the pressure of application choice steam, but for storage, suggestion remains on pressure below the 1500psi, because high pressure makes storage cost too high.For the Small-sized C P unit with live steam generation, this high pressure is in no case suitable: 1000psi is just enough in this case.On the other hand, overheated more than 1000 ℉ not only provides efficient but also provide low storage cost at least.

Fig. 6 shows and is used for the another embodiment of concentration solar generating unit 50 on a small scale.Solar collector 52 is provided with from the water of water pot 56 and in trap and produces superheated vapor 58, and this superheated vapor is supplied to steamturbine 60 to produce electric power at carry-out part 64 via controller 62.When to be lower than peak power when operation, extra or unnecessary superheated vapor 58 is in control device 62 is transferred to heat-storing device 66, and this heat-storing device stores the heat from the steam that shifts as mentioned before.Condensed water 55 turns back to jar 56 via controller 62.Fetch when hot when needs, will preferably be directed in the heat storage can 66 with convection type from the cold water 68 of jar 56 from the below.Water is converted into superheated vapor 70 and fetches and be used to drive turbine 60 to produce electric power at carry-out part 64 from the top of storage device 66.

The embodiment of Fig. 6 satisfies special needs: but to sunny but be not connected with electrical network and the remote districts of short-term fuel supplying and water supply electric power.This situation exists with the too expensive place that is connected of electrical network with foundation in many undeveloped countries.In order to supply small-sized village or city, the size of this unit should be between perhaps between the 50KW to 20MW.Every kilowatt of these small-sized unit are original just more expensive than large-scale unit, but they have certain competitive ability under the situation that does not have electrical network or mineral fuel, than the PV considerably cheaper that uses storage battery, and be essential in the place that can't obtain to be used for to build the resource of more large-scale unit.

Preferably, this Small-sized C P unit should have low maintenance demand and not need special full-time operator perhaps to move under many technician's the situation.In addition, wish bigger storage volume, preferably above one day.Water cooling should be unwanted.All these requirements are satisfied in design according to the present invention.

The feature of preferred embodiment is parabola shaped slot type trap or other complete trap, and wherein heat-exchange fluid is based on H ₂(for example, water is supplied to trap and is heated to form superheated vapor) of O.These traps can obtain with the design that can produce in enormous quantities from some companies (for example, Schott company).Superheated vapor can directly be supplied to the steamturbine that is designed to have air cooled back pressure turbine; Condensed water is recirculated to holding vessel and is recirculated to trap then.

If local condition allows that then this CSP unit can possess second function under the situation of back pressure turbine at turbine 60.The steam 74 that leaves back pressure turbine 60 can be used for the water source of locality is purified or desalination.As shown in Figure 6, steam 124 is applied to desalination boiler 126, wherein Shu Ru H ₂O is processed and as drinkable water H ₂O ^*Output.

Should be understood that: according to the present invention, provide a kind of stocking system, it can store the heat of superheated vapor and can produce when needed has identical overheated steam.This system is simple.Compressor or boiler are not set and a few pump only is set.Whole system can design and manufacture and be used for by truck transport so that assembling at the scene easily.In addition, it can be designed to control fully automatically.Its cost is also lower.

In this embodiment, have the position and can obtain the reliable energy, so this system is than the system's considerably cheaper based on the solar cell that combines with battery away from the undeveloped country in the small-sized local village of electrical network.Small-sized C P unit can be used to produce be used to communicate by letter, the electric power of refrigeration and illumination, and be used to purify local water source, irrigation and agricultural, and be used to Small Scale Industry that electric power is provided.In developing country, small-sized unit also can be used for the distribution type energy.Specific efficiency is lower and cost is higher mutually though they are with Generator Set, and still the alternative energy than any other form is more cheap for remote districts for they.In addition, be understandable that: though discussed specific embodiment in the literary composition, the direct use of steam is not limited to small-sized unit and can be used in the various benefited application.

The combined cycle generation unit:

Unique storage means has not only been contained in the present invention, and has contained its application.An application with many embodiments is that the steam in the combined cycle generation unit (CCPP) stores.

The combined cycle generation unit has the high-temperature fuel gas turbine, the thermal exhaust of this gas turbine is used for providing heat for attached steam electric power unit, the combined cycle generation unit is the most effective generator set (efficient is up to 60%) for vaporized fuel, is higher than any generator set based on mineral fuel.They can come fuel supplying by rock gas, diesel oil, methyl alcohol and other lighter clean fuel, and are used for providing from coal the IGCC generator set of clean electric power.Combustion gas CCPP supplies the U.S. at present and is using 20% of electric power.

But all CCPP all have such shortcoming: they can not carry out Steam Generator in Load Follow fast.Realize high efficiency, gas turbine must move in maximum load, and when load when being lower than 80% their efficient that becomes very low.But, they can in than the time of coal fired power generation unit much shorter, shut down and once more the starting, the latter have very high adjusting than (8: 1) but the starting to spend half a day at least.

The present extensive use of CCPP.The steam electric power unit of CCPP is partly supplied the 36-45% of CCPP unit total electricity, and itself has the high ratio of regulating.But,, can not utilize this control ability because the steam unit must receive all hot gass from gas turbine.But the present invention has changed this point fully to the innovation that stores steam.

According to the present invention, can be by any unwanted steam be transferred to heat storage units and controls the steam unit separately.Gas turbine is always all finished by the amount that control is supplied to the steam of steam turbine in the control of optimum capacity operation and all outputs, and all the other steam are transferred to storage device.In order to utilize stored steam, except that storage device, also provide other steamturbine, its size can be selected based on designed load-following capacity.Therefore, it can be greater than the steamturbine in the original unit, to provide bigger peak power or load-following capacity in the time period of designing.Therefore, provide the follow-up control of the quick load with 40% regulating power, and with in addition the big ratio short time increase the ability of power.This has changed the ability that Combined Cycle Unit is carried out Steam Generator in Load Follow fully.

Conventional steam electric power unit:

50% and worldwide most of electric power of American Electric Power still by the steam electric power unit supply of routine, supplied with by coal by major component, but some generator set combusting heavy oils, oil, coke and rock gas.Pollute the cost that control has increased them.Increase the needs that green energy resource has increased control function more feasible in the generator set to us to electrical network, and the present invention can provide this point.

Because their quick response and the high ratio of regulating, the equivalent steam generator set can only sufficient overload capacity be handled any load problem and high load changes by having, and this passes by the cause of being carried out just.But, the expensive and shortage at present of big overload capacity.At present, overload capacity is confined to the period of low electricity needs, such as night and weekend.But the control overwhelming majority is at high demand period needs.Simultaneously, the storage of steam can reduce the required overload capacity of power grid control and significantly more cheap replacement scheme is provided.

In the case, boiler full load operation all the time and superfluous steam are transferred to reservoir vessel from boiler feed water.But, in the large-scale conventional power generation usage unit of major part, superheated vapor 2500psi or even the high pressure that surpasses 3200psi (super critical condition) produce, and the reservoir vessel that is used to be higher than the pressure of 1500psi is expensive.

This problem has several solutions.In one embodiment, can extract all steam and store after reheater, wherein steam has suitably lower pressure.Even in the low period of demand, high-pressure turbine will generate electricity when needs electric power.In a second embodiment, steam can expand adiabaticly.For stored steam uses reheat turbine is unpractical, because steam needs when load surpasses maximum capacity (point that boiler is utilized fully) only; On the contrary, storage element plays the feasible effect that can obtain " boiler " of steam when needed.The special turbine that is used for stored steam can customize size according to system's needs, and if only use extra duty in the short time, then cause total output temporary transient more much bigger than the design capacity of generator set.This method is a kind of effective instrument of very cost that is used for handling peak load and fluctuation of load, allowing increases the short time overhead provision than building new coal fired power generation unit considerably cheaper ground, and ratio only increases to greater than the required capacity of stable operation the electric motor power of new generator set more cheap.

The underground heat unit:

The underground heat unit can easily carry out Steam Generator in Load Follow, and still, (that is, the reducing) capacity that because the prime cost of geothermal power is the cost of investment of specified vol, therefore redirects causes very big economic loss with the control Steam Generator in Load Follow.Storage device of the present invention has overcome this ground heat problem relevant with other generator set.The system that is used to store steam heat of the present invention allows in low period of electricity needs and therefore stores steam with low electricity price.When power cost is higher (, when demand is high) saved a large sum of spending when storage device reclaims electric power.This is because the storage cost of the every kWh of storage device of the present invention is more much lower than the price differential between high demand and the low demand.

Be understandable that now: according to the present invention, steam thermal energy can be fetched and use with very high efficient storage and in cost-effective mode.Superheated vapor itself can not store effectively with rational cost, but the invention provides with by at the high-temperature storage superheated vapor and fetch superheated vapor and store the same good solution of steam.

The invention solves a plurality of problems that prior art generator set and power industry are faced.The present invention can realize the storage of solar energy and can be implemented in the period generating that can not utilize solar energy.Conventional generator set can be furnished with heat storage capacity, to use it for extra capacity in non-peak value period store heat and in peak value period or any period when needing the control of Steam Generator in Load Follow and power network fluctuation.Possessing under the situation of this storage capacity, these generator set provide improved control function for electrical network.Equally, by setting up auxiliary turbine, can make the peak load capacity of generator set surpass its normal capacity and reduce needs the additional power generation unit that is used for peak demand.

Be understandable that: can implement specific variation and remodeling within the scope of the appended claims.Therefore, will be appreciated that: according to the present invention, other system, function, method and combination thereof are possible.In addition, though described the present invention with reference to specific embodiments of the invention and accompanying drawing, embodiment and accompanying drawing are exemplary, and scope of the present invention are not construed as limiting.

Claims

1. one kind has and is used to utilize the thermal fluid that is in about temperature T a or temperature T a that the generator set of the heat reservoir of stored heat is provided, and described system comprises:

A. the ceramic heat-storage medium that has the vertical section of prolongation of axis extension longitudinally, described medium is formed by particulate matter, described particulate matter cooperatively interacts and is limiting the space between the described particulate matter to help heat transfer fluid flow described flowing on vertically, vertical stream that described space mutually combines and passes described medium along described longitudinal axis to limit

B. described particulate matter and space can make described fluid cross flow along the plane perpendicular to described axis through described medium, described particulate matter is configured to limit the heat transfer between particulate matter and particulate matter, described particulate matter is configured to promote the direct transmission of heat and described fluid in the described plane and attractive and therefore limit heat front along described plane with the direct transmission of described fluid to heat, wherein said medium and fluid cooperate to conduct heat between described fluid and described medium along described plane, thereby form perpendicular to described axis and along the described heat front on described plane

C. described particulate matter stops heat transfer and attractive to flash heat transfer by directly contacting with described fluid simultaneously by contacting with each other, and

D. described stream has and is used for the port that passes through for overheated working fluid, described stream described port have be used for described flow stop after storage be in the zone of heat of the described overheated working fluid of temperature T a.

2. system according to claim 1, also comprise stream controller, described controller is controlled the flow rate of described fluid, when being selected to and guaranteeing that described particulate matter and described fluid are in described plane, wherein said flow rate reaches described temperature T a along described plane, described stream has and is used for the port that passes through for the fluid of described heating that is in temperature T a, and the vapor phase of described fluid is used as the working fluid in the described system.

3. system according to claim 2, also comprise and be used to hold described medium and have the transfer fluid cools port and the container of the overheated port of thermal fluid, described stream has superheat region and boiling range, in the zone of described cooling port, described stream will be transported to described boiling range as the described fluid of the liquid that is lower than described boiling temperature, described stream stores the heat as the described fluid of the superheated vapor that is in temperature T a in the zone of described overheated port, and described stream stores the heat as the described fluid of boiling liquid in described boiling range.

4. system according to claim 3, described particulate matter also comprises heat storage material and thermoinsulation material, the well-regulated porous heat insulation layer that also comprises described thermoinsulation material in described stream is to prevent in described leading edge temperature gradient owing to the transmission of heat of passing described particulate matter reduces.

5. system according to claim 3, wherein, described heat insulation layer is channelled plate, described plate is made by thermoinsulation material.

6. system according to claim 3, wherein, described heat insulation layer is the adiabatic particulate matter that one deck size is similar to Heat Conduction Material.

7. system according to claim 1, described stream has following ability: be stored in the heat of the steam that produces in the concentration solar generating unit, by supplying water to reservoir vessel this steam of regenerating, so that transmit the steam of described regeneration when needed.

8. system according to claim 1, described stream has following ability: the heat that is stored in the steam that produces in the steam boiler of combined cycle generation unit when not needing steam to generate electricity, after this when needing, in independent turbine, use stored steam, thereby provide load-following capacity and storage to Combined Cycle Unit.

9. system according to claim 8, wherein, described additional steamturbine is greater than the steamturbine of unit itself and provide bigger short-term load-following capacity to be used for stablizing electrical network.

10. system according to claim 1, wherein, described unit is that the integrated gasification combined cycle for power generation unit is to provide better load-following capacity to it.

11. system according to claim 1, wherein, described unit is the coal-fired steam generator set.

12. system according to claim 1, wherein, described stream has the ability of the heat that stores steam, wherein extracts the steam that is used to store with reduction pressure from the outlet of the high-pressure turbine of steam electric power unit reheater after.

13. a heat-storing method that is used to use the thermal fluid that is in about temperature T a or temperature T a that stored heat is provided in generator set said method comprising the steps of:

E., the ceramic heat-storage medium of the vertical section of prolongation with axis extension longitudinally is set, described medium is formed by particulate matter, described particulate matter cooperatively interacts and is limiting the space between the described particulate matter to help heat transfer fluid flow described flowing on vertically, vertical stream that described space mutually combines and passes described medium along described longitudinal axis to limit

F. be arranged to make described fluid cross to flow along plane described particulate matter and space perpendicular to described axis through described medium, described particulate matter is configured to limit the heat transfer between particulate matter and particulate matter, described particulate matter is configured to promote the direct transmission of heat and described fluid in the described plane and attractive and therefore limit heat front along described plane with the direct transmission of described fluid to heat, wherein said medium and fluid cooperate to conduct heat between described fluid and described medium along described plane, thereby form perpendicular to described axis and along the described heat front on described plane

G. described particulate matter is arranged to stop by contacting with each other simultaneously heat transfer and attractive to flash heat transfer by directly contacting with described fluid, and

H. described stream is arranged to have and is used for the port that passes through for overheated working fluid, described stream described port have be used for described flow stop after storage be in the zone of heat of the described overheated working fluid of temperature T a.

14. method according to claim 13, stream controller also is set, described controller is controlled the flow rate of described fluid, when being selected to and guaranteeing that described particulate matter and described fluid are in described plane, wherein said flow rate reaches described temperature T a along described plane, described stream has and is used for the port that passes through for the fluid of described heating that is in temperature T a, and the vapor phase of described fluid is used as the working fluid in the described system.

15. method according to claim 13, also be provided for holding described medium and have the transfer fluid cools port and the container of the overheated port of thermal fluid, described stream has superheat region and boiling range, in the zone of described cooling port, described stream will be transported to described boiling range as the described fluid of the liquid that is lower than described boiling temperature, described stream stores the heat as the described fluid of the superheated vapor that is in temperature T a in the zone of described overheated port, and described stream stores the heat as the described fluid of boiling liquid in described boiling range.

16. method according to claim 13, also described particulate matter is arranged to comprise heat storage material and thermoinsulation material, the well-regulated porous heat insulation layer that comprises described thermoinsulation material in described stream is to prevent in described leading edge temperature gradient owing to the transmission of heat of passing described particulate matter reduces.

17. method according to claim 15, wherein, described heat insulation layer is channelled plate, and described plate is made by thermoinsulation material.

18. method according to claim 15, wherein, described heat insulation layer is the adiabatic particulate matter that one deck size is similar to Heat Conduction Material.

19. method according to claim 13, also described stream is arranged to have following ability: the heat that is stored in the steam that produces in the concentration solar generating unit, by supplying water to reservoir vessel this steam of regenerating, so that transmit the steam of described regeneration when needed.

20. method according to claim 13, also described stream is arranged to have following ability: the heat that when not needing steam to generate electricity, is stored in the steam that produces in the steam boiler of combined cycle generation unit, after this when needing, in independent turbine, use stored steam, thereby provide load-following capacity and storage to Combined Cycle Unit.

21. method according to claim 20, wherein, described additional steamturbine is greater than the steamturbine of unit itself and provide bigger short-term load-following capacity to be used for stablizing electrical network.

22. method according to claim 13, wherein, described unit is that the integrated gasification combined cycle for power generation unit is to provide better load-following capacity to it.

23. method according to claim 13, wherein, described unit is the coal-fired steam generator set.

24. method according to claim 13, wherein, described stream has the ability of the heat that stores steam, wherein extracts the steam that is used to store with reduction pressure from the outlet of the high-pressure turbine of steam electric power unit reheater after.

25. a heat reservoir that is used to provide the heat of the storage that is in the thermal fluid X about temperature T a or temperature T a, described system comprises:

A) have the container of transfer fluid cools input part and the overheated carry-out part of thermal fluid, described container has the vertical section that is communicated with described input part and carry-out part,

B) the ceramic heat-storage medium in described vertical section, described medium has main longitudinal axis and time axis, described medium is formed and limits the space and flows and the heat transmission to help fluid between described particulate matter by particulate matter, the vertical stream of master that described space cooperatively interacts and extends along described main axis to limit in described vertical section

C) described stream flows so that seethe with excitement to the fluid that described boiling range supply is lower than boiling temperature, and it is overheated so that described stream is heated to that described stream is supplied described boiling stream to described superheat region, and

D) stream controller, described controller is set the flow rate of described fluid stream, described flow rate makes it possible to realize heating by a series of thin slices of the described overheated particulate matter in the particulate matter of the described boiling in the described boiling range and the described superheat region, each described particulate matter thin slice is being limited perpendicular to the cross section in described the axis of described main axis by described particulate matter, described thin slice is heated and heats the described stream of part amount, described part amount is seethed with excitement in described boiling range and is superheated in described superheat region about temperature T a or temperature T a, and the described thermal fluid X that is in then about temperature T a or temperature T a is output at the overheated carry-out part of described thermal fluid.