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Removable heat exchanger insertsRelated Patent Categories: Heat Exchange, Flow Passages For Two Confined Fluids, Interdigitated Plural First And Plural Second Fluid Passages, Stacked Plates Or Shells Form Interplate Passages, With Plate Traversing Passages Interconnecting Alternate SpacesRemovable heat exchanger inserts description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080000624, Removable heat exchanger inserts. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This invention relates to heat exchangers. It is particularly, but not exclusively, concerned with heat exchangers that are to be used as chemical reactors and, although not intended to be limited thereto, it will be more specifically described below with particular reference to catalytic reactors. [0002] Heat exchanger constructions are well known in which passageways for fluid are provided between adjacent walls defined by parallel spaced plates which provide primary heat exchange surfaces, and in which the passageways contain secondary heat exchange surfaces in the form of fins, which may conveniently be in the form of a corrugated sheet or finning extending along the passageways. [0003] It is conventional practice to braze or otherwise bond the corrugated finning to the passageway walls during brazing or otherwise bonding of the passageway walls to form the heat exchanger structure. In other words, the corrugated finning is bonded in situ during the manufacture of the heat exchanger body and it is conventional practice to utilise the presence of the corrugated finning to assist in transmitting the loads applied by jigging during the bonding/brazing process. [0004] Where the heat exchanger is to be used as a chemical reactor, it is frequently required that passageways contain catalyst to catalyse the desired reaction in the fluids passing through those passageways. For an exothermic reaction, the reactor may be designed to have passageways to carry a cooling fluid across the opposite faces of the primary surfaces to the faces contacting the reacting fluid so that the heat of reaction can be carried away. If the reaction is endothermic, a heating fluid may be needed to transfer heat across those primary surfaces to initiate the desired reaction. [0005] Two basic systems have hitherto been proposed to introduce catalyst into those passageways carrying the fluid to be reacted. In one, the internal surfaces of the passageways are coated with a catalyst, usually in finely divided form, e.g. of particle size 150 microns or less. In the second, the passageways are packed with catalyst, which may, for example, be of particle size 2 to 3 mm or greater. The second system is more suitable for use with relatively open, unobstructed passageways whereas the first system is more suitable for use with smaller passageways which may contain secondary finning. It is usual to coat the catalyst onto the primary and secondary surfaces after they have been bonded together to avoid damage to the catalyst and its adhesion properties during the bonding process. The catalyst is applied by well known coating techniques in which a solution or suspension of the catalyst is brought into contact with the passageway surfaces by dipping, and/or flowing with the solution or suspension and then stoving at the appropriate temperature. [0006] Packed catalyst particles of the second system can be removed when spent or contaminated simply by being forced out of the passageways, e.g. by means of a rod, and the passageways can then be repacked with fresh catalyst. Spent or contaminated catalyst of the first system is much more difficult to remove from the relatively complex internal passageway surfaces and the reactor, therefore, may have only a short service life and have to be scrapped when the catalyst is spent. [0007] The Chemical Industry has traditionally utilised catalysts in order to initiate/control various chemical reactions but the applications are now becoming much wider. A significant growth in usage could occur with the advent of miniaturised chemical reactors in conjunction with the introduction of Process Intensification and Fuel Cells. [0008] The traditional method of installing catalyst is to pack tubes/passageways with appropriate particles and control the temperature of the reaction by passing a cooling or heating medium over the outside of the tubes. Development of catalyst and processes has now resulted in a preference, for some applications, for finely divided catalyst particles to be coated onto the internal surfaces of the reactors. One method of enhancing the surface area available for coating and hence improving the performance of a reactor is to fit an insert into each passageway. The inserts are specially designed to meet these requirements. [0009] Effective coating of the inserts can be more readily achieved and controlled with such a system. [0010] Although more efficient than traditional methods, the coated catalyst may still have a reduced life as a consequence of fouling etc, requiring it to be capable of being changed more frequently. Thus having the opportunity of removing the insert, re-coating and re-installing would be particularly advantageous. [0011] In a heat exchanger with relatively open passageways it may be desirable to provide an insert to increase the heat exchange capacity of the reactor. The ability to remove, clean and replace such inserts would also be desirable. [0012] It is, therefore, an object of the invention to provide an improved heat exchanger, particularly useful as a catalytic chemical reactor, in which the above-mentioned problem of coated catalytic reactors can be obviated, and/or a heat exchanger in which inserts to increase heat exchange capacity can be removed, cleaned and replaced. [0013] A further feature of the invention concerns solid catalysts, which are used in the chemical processing industry for the enhancement of chemical reactions Typically the catalyst would form a thin surface over which the process fluid flows Solids are widely used for other processing applications including adsorption processes both involving chemical reactions and as a physical process. [0014] Adsorption is the action of molecules transferring from a fluid phase adsorbate (either gas or liquid) onto a solid phase adsorbent. This can result in a chemical reaction between fluid and solid, be a means for the solid to capture specific components from the fluid phase, in this way acting as a separator, or the structure acts as a storage device holding a fluid in place. Adsorbents are typically porous to provide a high surface area per unit volume. Typical adsorbents are silica gel and activated carbon. [0015] Applications of adsorption include [0016] heat pump adsorption cycles, where the adsorbent provides the means for holding the liquefied refrigerant during phase changes between gas and liquid, thereby releasing or absorbing heat (known as sorption chillers) [0017] gas purification where one or more specific components in the gas can be removed from the bulk gas flow [0018] to provide contact for chemical reactions between fluids and solids. [0019] Adsorption is accompanied by the liberation of heat, even when there is no chemical reaction involved. Under many circumstances adsorption can be reversed so the captured component is desorbed by reversing the conditions (temperature, pressure) that were applied to promote adsorption. If the heat of adsorption cannot be removed by cooling, the capacity of the adsorbent will be reduced as its temperature increases. [0020] Standard adsorbers consist of packed beds of granular or pellet adsorbent through which the process fluid passes. [0021] It is a further object of the invention to provide an insert for receiving solid or granular adsorbent which can also act as a catalyst. [0022] It is also known that processes can occur where it is desirable to separate one component from a process stream. This can occur, for example, during gaseous reactions when the removal of a reaction product can affect the equilibrium and therefore promote the production of more of that product. Membranes can also be used for this purpose. [0023] Membranes can be in the form of ceramic, fibrous or polymeric solids. The membrane will allow the separation of a specific component or components, acting in the manner of a filter. Hydrogen is an example of a component that can be separated from gaseous streams through the use of a membrane. [0024] A stack can be made up using inserts described herein, both slotted plate and pin-fin types. [0025] According to one aspect of the invention there comprises a heat exchanger or chemical reactor comprising a heat exchange body defining a plurality of flow passages and a removable insert defining secondary heat exchanger surfaces retained within at least one of the flow passages, by insert retention means, characterised in that the insert comprises one or more plate(s) having perforations to define discrete fluid flow channels extending across the plate(s) and wherein one or more of the plates is provided with a carrier for a catalyst or adsorbent. [0026] Optionally, the body comprises an elongate tube with the wall of the bore of the tube constituting a flow passage. [0027] Preferably, one or more of the plates are of different thicknesses with respect to the other plates in such a stack. More preferably, the insert retention means is provided at least in part by the stack which is slightly greater in height than the height of the fluid passage to provide an interference or push fit. Continue reading about Removable heat exchanger inserts... Full patent description for Removable heat exchanger inserts Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Removable heat exchanger inserts patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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