MX2012008118A

MX2012008118A - Heat transfer interface.

Info

Publication number: MX2012008118A
Application number: MX2012008118A
Authority: MX
Inventors: Eugene Thiers
Original assignee: Sylvan Source Inc
Priority date: 2010-01-12
Filing date: 2011-01-12
Publication date: 2012-09-12
Also published as: SG182455A1; US20130056193A1; CA2787219A1; AU2011205326B2; IN2012DN06402A; MX339872B; JP2016166735A; AU2011205326A1; EP2523752A1; WO2011088132A1; JP2013517451A; EP2523752A4; CN102844104A; ZA201205975B

Abstract

Embodiments of the invention provide systems and methods for heat management systems at temperatures in the range of 1200 C to 1,3000 C. The systems consist of various heat transfer chambers configured such that they contain heat transfer devices that are spherical, cylindrical or have other shapes, and that absorb heat within a broad range of temperatures, and return such heat at constant temperature over long periods of time.

Description

THERMAL TRANSFER INTERFACE FIELD OF THE INVENTION The present invention is concerned with the field of heat management. In particular, the embodiments of the invention are concerned with systems and methods for storing heat from industrial operations and recovering such heat at a constant temperature over long periods of time.

BACKGROUND OF THE INVENTION Many industrial operations today generate large amounts of waste heat, which is dissipated in evaporation towers (ie, cooling towers), transferred to cooling water, converted into steam or wasted into the surrounding environment. In addition, numerous industrial activities are intermittent by nature, in such a way that the heat generated in those operations is not continuous but only lasts a limited time and the temperature of those heat sources varies widely, thus making heat recovery and recycling of difficult and annoying heat. As a result, large amounts of energy are systematically wasted in cooling water streams, low-grade steam or simply dissipated, thus making such industrial operations more energy intensive than is necessary.

In addition, many exothermic polymer reactions in the petrochemical industry require precise temperature control, which is commonly obtained using double-walled reactors with cooling water. However, although such reactors use large volumes of cooling water in the outer jacket and turbulence, temperature control is difficult because heat is generated throughout the reactor's internal volume and away from the cooling wall. In addition, those cooling systems generate large volumes of cooling water at temperatures that are too small for effective heat recovery. As a result, those petrochemical operations waste significant amounts of heat and water and incur substantial costs in water treatment facilities before discharging such waste.

The molten salt systems have been developed to store heat at high temperatures and are mainly used with solar concentrators. Such systems depend on the heat of fusion that is commonly much larger than the specific heat per unit mass and are able to release that heat continuously after solidification or freezing. Sodium metal is also used for storage of heat at higher temperatures, although in the case of sodium, heat storage occurs mainly by heating liquid sodium to a higher temperature. Conventional molten salt systems and molten sodium systems suffer from two main problems: what to do when there is a system failure and salt or sodium freezes and the need to pump a semi-viscous medium at high temperatures.

Thus, there is a need for a non-expensive heat transfer medium that can absorb heat at a high temperature, can administer such heat at a constant temperature over a long period of time, requiring little or no maintenance and being reliable and can be easily manipulated even if the heat transfer medium is frozen.

There are numerous technologies related to the management or storage of energy or heat using molten salts. However, the vast majority of these technologies offer little relevance to the present invention because they involve different functionalities. So, many are or concerning ion exchange resins, some with polymer systems and some with thermoplastic, all of which involve organic polymers that are notorious for their susceptibility to thermal degradation at relatively moderate temperatures; others are concerned with the treatment of underground heat from hydrocarbon deposits and materials that are frequently encapsulated or refer to phase change inks, organic pigment compositions and imaging systems. Some technologies are concerned with pharmaceutical or biological systems, while others are concerned with flame retardants or flame retardants, all of which have little relevance to heat management or storage systems using phase change salts.

Many technologies employ phase change materials which are mainly salts and many use eutectic compositions of various salts, but they are frequently encapsulated and thus share the problem of freezing in solidification.

Some technologies are concerned with energy storage systems based on phase change materials and employ heat pipes in connection with such heat storage systems that include heat exchangers. Others employ phase change materials that are compacted in powder form and encapsulated by a rolling process. However, the normal problems encountered with the use of heat exchangers using molten salts are exacerbated and the encapsulation methods employed involve expensive manufacturing and are restricted to simple forms.

Other technologies employ hydrated metal nitrates that minimize the density changes between the solid and liquid phases. However, hydrated salts easily lose water of hydration during heating and such chemical changes commonly occur at or before reaching the melting point of those substances. As a result, any free water is likely to evaporate, leading to buildup of pressure inside any enclosure. Thus, key elements of these technologies make them unsuitable for use in the applications described above.

Some technologies involve the use of crystallization inhibitors to lower the solidification temperature of the phase change materials, while others employ similar systems using a separate crystal nucleator.

Other technologies are concerned with methods for storing heat within a wide range of temperatures by using various phase change salt materials and a porous support structure. However, a common difficulty in all such phase change systems is the lack of flowability, that is, the fact that as the phase change material freezes, it no longer flows.

Still other technologies describe anhydrous sodium sulfate and similar phase change salts in relation to a heat exchanger configured to provide uniform heat distribution in all phase change materials. However, the common deficiency of such systems is the same as described above, that is, the fact that in freezing such materials completely lose the flow capacity.

Other methods employ heat tubes and mechanisms to scrape a salt eutectic from the tubes, while the molten salt provides the heat for boiling water. However, the eutectic compositions have the problem that such salt mixtures tend to exhibit higher solubilities for materials enclosing the phase change salt.

BRIEF DESCRIPTION OF THE INVENTION Modes of the present invention provide an improved method for heat management, one that allows the rapid capture of heat at temperatures in the range of 120 ° C to 1300 ° C from a variety of heat sources and the subsequent release of such heat at a constant temperature for a long period of time. The system may include an internal heat transfer medium encapsulated in an external container which may be cylindrical, spherical or other shape and which is inert with respect to the heat source. The heat transfer medium can include salts, metals or ceramic compositions and is able to remove heat by absorbing the heat of fusion of a heat source. The encapsulation vessel may include a metal, plastic or ceramic composition that is not. reactive with respect to the heat source and not reactive with respect to the heat transfer medium. In system modalities, the size and shape of the encapsulation vessel is determined by the nature and chemical characteristics of the heat source and by. the heat transfer requirements in terms of removal or release of heat per unit volume and per unit time.

BRIEF DESCRIPTION OF THE FIGURES Figures la and Ib are elevation views of two embodiments of encapsulated heat transfer devices.

Figures 2a and 2b are embodiments of heat transfer devices with internal coatings.

Figures 3a and 3b are elevational views of heat transfer devices with internal and external coatings.

Figures 4-a and 4-b show two possible embodiments of heat transfer devices within different configurations of heat transfer reactor.

Figure 5-a is a schematic diagram of a double-walled petrochemical reactor chamber.

Figure 5-b is a simplified petrochemical reactor with randomly dispersed heat transfer devices.

Figure 6 is a schematic diagram of a basic steel oxygen converter with a heat recovery chamber.

Figure 7 is a schematic diagram of a two-step boiler system with a heat recovery chamber.

Figures 8a and 8b are elevation and plan views of a chamber of a double coaxial heat recovery chamber with heat transfer devices.

DETAILED DESCRIPTION Modes of the invention are disclosed herein, in some cases in exemplary form or by reference to one or more figures. However, any of such disclosures of a particular embodiment is exemplary only and is not indicative of the full scope of the invention.

Modes of the invention include systems, methods and apparatus for the handling, recovery and recycling of heat from a variety of industrial operations. Preferred modes provide a wide spectrum of heat absorption chambers that operate within a temperature range of 120 ° C and 1300 ° C and provide a fully automated heat recovery at temperatures similar to that interval in several hours, days or months without user intervention. For example, the systems disclosed herein may operate without control or user intervention for 2, 4, 6, 8 months or more. In preferred embodiments, the systems can operate automatically for 1, 2, 3, 4, 5, 6, 7, 8 years or more.

Modes of the invention provide encapsulated heat transfer devices of various shapes and sizes to enter and exit heat transfer chambers at a rate commensurate with the amount of waste heat available and its temperature. Thus, the encapsulation of heat transfer devices in rigid impermeable enclosures allows such devices to flow either propelled by the gravity of mechanical systems regardless of the state of the enclosed material, which is commonly a salt or salt mixture, thus providing the flow. When heat is available, it is easily absorbed by the phase change material that is encapsulated, which is first heated to its melting point and then continues to absorb the heat of fusion until all the encapsulated material is melted. When heat is required, the encapsulated material is transferred to another heat transfer chamber where the molten phase change material begins to solidify, thereby releasing the same heat of fusion that was previously absorbed.

The heat transfer chambers can be of any size and shape that is compatible with the amount of heat available, the length of time such heat is available and its temperature. Those three variables determine the size and shape of the heat transfer devices that are used, so that they will have a residence time in the transfer chamber equal to that of the heat that is available and its mass of phase change material. it will be appropriate to the amount of heat and temperature available ..}.

Important characteristics of heat transfer chambers is that they allow the movement of heat transfer devices in and out of such a chamber, such as by gravity flow, although another form of mechanical transport can be employed.

Important characteristics of heat transfer devices are that they are durable, not expensive to manufacture and thermally effective. The durability requires a lack of chemical interaction between the enclosure material of the device and the internal phase change material. The non-expensive manufacture requires that the enclosed phase change material be encapsulated in waterproof containers that are easy to manufacture, such as crimped metal cylinders, metallic or ceramic spheres and the like. The thermal effectiveness requires that the thickness of the envelope material be small and thermally conductive and that it does not react chemically with either the external environment providing the heat or the internal environment of the phase change material.

In preferred embodiments, such as those shown in Figures 1A and IB, the heat transfer device (1) consists of a cylinder or sphere comprising the wrapping material (2) or similar shape that is filled with the exchange material of phase (3) which may be an inorganic salt or mixture of salts. The cylinder or sphere is made of metal, such as copper or aluminum or a similar non-expensive metal. In other embodiments, the wrapping material (2) can be made of a thin ceramic or polymer material that becomes thermally conductive by incorporating metal powders or chips. In preferred embodiments, the wrapping material (2) consists of a tube of aluminum, copper or similar crimped metal, a welded tube or a similarly shaped tube equipped with a screw cap.

Figures 2a and 2b illustrate an alternative embodiment of a heat transfer device (1) in which the inner surface of the wrapping material is coated with an inert substance (21) that is chemically non-reactive with the surrounding materials (2) or with the phase change material (3). As used in this application, "non-reactive" encompasses both completely non-reactive materials and chemically reactive materials, but in which the reaction is so slow or light that there is no appreciable effect on the chemical properties of the materials or structure of the heat transfer device. Suitable coatings include metals and electrodeposited alloys, paints, ceramic compositions or polymers. Examples of non-expensive coatings on copper, aluminum and similar materials include carbides, nitrides, oxides. Examples of coating methods include chemical vapor deposition, electrostatic deposition, anodizing, electrolysis and painting. Useful information concerning corrosion and coatings is provided in Handbook of Corrosion Engineering, which is incorporated herein by reference in its entirety.

Figures 3a and 3b illustrate alternative embodiments of a heat transfer device (1) in which both of the inner and outer surfaces of the wrapping material (2) are coated with inert substances (21) and (31) which are chemically non-toxic. reactive either with the enclosing material (2), the phase change material (3) or the external environment in which the heat transfer device is in operation. Suitable coatings include metals and electrodeposited alloys, paints, ceramic compositions or polymers. Examples of non-expensive coatings on copper, aluminum and similar materials include carbides, nitrides, oxides. Examples of coating methods include chemical vapor deposition, electrostatic deposition, anodizing, electrolysis and painting.

Figure 4a illustrates a possible embodiment of a heat transfer chamber (4) consisting of a cylindrical configuration containing a plurality of heat transfer devices (1) that are randomly arranged to provide sufficient porosity to the flow of a medium of fluid that contains heat. Figure 4b illustrates another modality of a heat transfer chamber (4) consisting of a rectangular configuration containing a plurality of heat transfer devices (1) that are randomly arranged to provide sufficient porosity to the flow of a fluid medium containing heat. Other geometric shapes used to contain the heat transfer devices are also possible. Those skilled in the art will recognize that cylindrical or rectangular shapes are exemplary only and that other shapes can be used to conform to space constraints and arranged by the type of heat source in different industrial applications.

Figure 5a is a simplified diagram of a double-walled petrochemical reactor, typical of catalytic processes involving endothermic reactions. In Figure 5a, the reactor (6) consists of two concentric cylindrical tanks that allow cooling water to enter through the gates (62) and exit through the gates (63), to provide cooling for the exothermic heat generated in the reactor volume (61). Such reactors are widely used to control the temperatures of react in the chemical industry and are notorious for requiring large volumes of cooling water and the extensive use of pumps. Figure 5b illustrates a simplified reactor configuration consisting of a reactor (6) comprising a single tank and a plurality of heat transfer devices (1) that provide more efficient cooling of exothermic reactions.

Figure 6 illustrates the heat recovery of a basic oxygen furnace (7) in a steel plant. Commonly, those furnaces are coated with special refractories (71) that are initially charged with molten iron (72) from a blast furnace, some alkaline fluxes and some steel slag (73) used to cool the molten iron. Once the furnace is loaded, an oxygen lance (74) blows oxygen to the molten iron to oxidize the excess carbon in the cast iron and create steel. The reaction of oxygen with the dissolved carbon in the molten iron is a highly exothermic reaction that raises the temperature of the molten charge and creates large volumes of very hot gases at temperatures that normally exceed 1500 ° C. Hot gases that consist extensively of C02 leave the furnace at the top and are collected in a bell (75). The hot gases carry a huge amount of heat that is extensively captured by the heat transfer devices (1) that are flowing into a heat transfer chamber (5) in such a way that the residence time inside the The camera precisely balances the amount of heat that is produced by hot gases.

* Figure 7 illustrates the heat recovery of a boiler or industrial boiler (8). Commonly, a burner 81 provides the necessary heat by burning a fuel in the home. The hot combustion gases initially transfer heat to a plurality of high pressure steam tubes (82) and subsequently to a plurality of water boiling tubes (83) and a pre-heater chamber (84) and exit through the fireplace (85). A heat transfer chamber (5), connected to the chimney (85), recovers the heat contained in the hot combustion gases by transferring the heat to a plurality of heat transfer devices (1) which moves through the the chamber (5) at a speed commensurate with the residence time required to capture the heat contained in the combustion gases.

Figure 8a and 8b illustrate an elevational view and a plan view of a system (9) for recovering useful heat from the heat transfer devices (1). In Figure 8a, two concentric chambers (91) and (92) allow heat transfer devices at high temperature (11) at very high temperature to transfer heat to lower temperature heat transfer devices (12), to prolong the period of heat recovery at lower temperatures. Thus, the heat that has been captured at very high temperature but for limited amounts of time becomes available on a continuous basis at a lower temperature. As will be appreciated by that of skill in the art, different configurations can be used to transfer heat from high to low temperatures and other forms than cylindrical or rectangular chambers can be used.

The heat transfer devices can be manufactured from any suitable material. Exemplary materials for enclosing means of phase change include but are not limited to metal, glass, composites, ceramics, plastics, - stone, cellulose materials, fibrous materials and the like. A mixture of materials can be used if desired. Those of skill in art will be able to determine the appropriate material for each specific purpose. The chosen material will preferably be able to withstand long term use at high temperature without cracking, rupture, other significant damage or leaching of toxic materials into the environment. If desired, the differently sized devices may be of different materials. For example, enclosures for high temperature heat transfer devices can be made of metals such as steel, titanium or various alloys and the phase change medium can consist of salts having high melting points. The material chosen may preferably be resistant to rupture, oxidation or cracking due to the heating process. Table 1 lists several metals with their melting points and their heat of fusion for or facilitate the selection of appropriate enclosure materials.

Table 1 Table 2 lists several salts and provides melting points arranged in ascending order, also as the corresponding heat of fusion. The information in Table 2 serves to select appropriate phase change media for different industrial applications and heat recoveries at various temperatures.

Table 2 5 10 fifteen 25 In addition to phase change materials, chemical reactions involving reduction / oxidation (REDOX) can also provide heat storage and controlled heat release and can thus be used with media for heat transfer applications. For example, the carbonate / bicarbonate reaction commonly involves a chemical change that can be reversed after minor changes in temperature. Thus, the ammonium bicarbonate decomposes to ammonium carbonate when the temperature changes a few degrees centigrade and the heat of this reaction can be either absorbed or released, thereby providing functionality similar to that of the phase change materials.

As used in this application, REDOX reactions include those in which one or more electrons are exchanged and thus encompasses a broader group of chemical reactions than simply those involving oxygen as an oxidant.

Commonly, the chemical reactions of interest in this application include those in which one of the reactants is an organic material. Such chemical reactions are characterized by heats of reaction that are acutely dependent on the temperature of the system.

The skilled artisan will appreciate that these methods and devices are and may be apt to carry out the objects and obtain said ends and advantages, as well as various other advantages and benefits. The methods, methods and devices described herein are currently representative of preferred embodiments and are exemplary and are not intended to be limitations as to the scope of the invention. Changes in them and other uses will be presented to those experienced in the art who are encompassed in the spirit of invention and are defined by the scope of the revelation.

The invention described illustratively herein may be properly practiced in the absence of any element or elements, limitation or limitations that are not specifically disclosed herein. The terms and expressions that have been used are used as terms of description and not limitation and there is no intention that the use of such terms and expressions indicate the exclusion of equivalents of the elements shown and described or portions thereof. It is recognized that several modifications are possible in the scope of the disclosed invention. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional elements, modification and variation of the concepts disclosed herein may be resorted to by those skilled in the art and that such modifications and variations are considered to be. they are within the scope of this invention as defined by the disclosure.

Claims

1. A heat management system characterized in that it comprises a plurality of heat transfer particles, each consisting of an internal heat transfer medium encapsulated in an external container which is inert with respect to the heat source and which is suitable for the rapid capture of heat at temperatures in the range of 120 ° C to 1300 ° C from a heat source and the subsequent release of heat at a constant temperature over a period of time.

2. The system of claim 1, characterized in that the heat transfer medium comprises a material selected from the group consisting of a salt, metal and a ceramic composition and is capable of removing heat from an environment by absorbing the heat of fusion of the source of heat.

3. The system of claim 1, characterized in that the container comprises a material selected from the group consisting of a metal, plastic or ceramic composition that is not reactive with respect to the heat source and non-reactive with respect to the heat transfer medium. .

4. The system of claim 2, characterized in that the heat transfer medium has a melting temperature in a range of 120 ° C - 1300 ° C.

5. The system of claim 2, characterized in that the heat transfer medium comprises a material selected from the group consisting of a chloride, oxychloride, fluoride, sulfate sulfite, carbonate, bicarbonate, borate, arsenate, aluminate, bromide, chromate, hydride, manganate, silicate, sulfur, titanate, telluride, selenide, oxide, hydroxide, metal and mixtures thereof.

6. The system of claim 2, characterized in that the heat transfer medium comprises a substance having a boiling point or a decomposition temperature which is at least 100 ° C higher than the melting temperature thereof.

7. The system of claim 2, characterized in that the heat transfer medium comprises a substance having a very low vapor pressure at its melting temperature.

8. The system of claim 2, characterized in that the heat transfer medium comprises two or more substances that react chemically at a given temperature and absorb during this the heat of that reaction.

9. The system of claim 8, characterized in that the heat transfer medium decomposes at a given temperature and thereby releases the heat of reaction to the environment.

10. The system of claim 3, characterized in that the container comprises a material selected from the group consisting of copper, aluminum, chromium, iron, lead, magnesium, nickel, metal alloy, high temperature plastic such as fluorocarbon or chlorofluorocarbon or a ceramic such as silicate, alumina and similar refractory composition.

11. The system of claim 3, characterized in that the internal surface of the container is coated with a substance that is non-reactive with the heat transfer medium.

12. The system of claim 3, characterized in that the internal surface of the container is coated with a substance that is non-reactive with the heat source.

13. The system of claim 9, characterized in that the coating of the container comprises a material selected from the group consisting of a carbide, oxide, silicate, polymer, metal or similar non-reactive composition with respect to the heat transfer medium.

14. The system of claim 10, characterized in that the coating of the container comprises a material selected from the group consisting of a carbide, oxide, silicate, polymer, metal or similar non-reactive composition with respect to the heat source.

15. The heat management system of claim 1, characterized in that the heat transfer particles include a plurality of phase change materials suitable for a temperature range, such that the system recovers heat at several constant temperatures of the particles .

16. The system of claim 13, characterized in that the heat source comprises waste heat from chemical reactors that handle exothermic reactions.

17. The system of claim 13, characterized in that the heat source comprises waste heat from steel furnaces.

18. The system of claim 13, characterized in that the heat source comprises waste heat from industrial boilers.