Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including heat exchanger for reaction chamber or reactants...
Reexamination Certificate
2000-11-28
2004-03-23
Johnson, Jerry D. (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including heat exchanger for reaction chamber or reactants...
C422S198000, C165S166000, C165S173000, C165SDIG003, C165SDIG003
Reexamination Certificate
active
06709640
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to plate type exchanger arrangements for containing a reaction zone and indirectly heating the reaction zone with a heat exchange fluid.
BACKGROUND OF THE INVENTION
In many industries, like the petrochemical and chemical industries, contact of reaction fluids with a catalyst in a reactor under suitable temperature and pressure conditions effects a reaction between the components of one or more reactants in the fluids. Most of these reactions generate or absorb heat to various extents and are, therefore, exothermic or endothermic. The heating or chilling effects associated with exothermic or endothermic reactions can positively or negatively affect the operation of the reaction zone. The negative effects can include among other things: poor product production, deactivation of the catalyst, production of unwanted by-products and, in extreme cases, damage to the reaction vessel and associated piping. More typically, the undesired effects associated with temperature changes will reduce the selectivity or yield of products from the reaction zone.
Exothermic reaction processes encompass a wide variety of feedstocks and products. Moderately exothermic processes include methanol synthesis, ammonia synthesis, and the conversion of methanol to olefins. Phthalic anhydride manufacture by naphthalene or orthoxylene oxidation, acrylonitrile production from propane or propylene, acrylic acid synthesis from acrolein, conversion of n-butane to maleic anhydride, the production of acetic acid by methanol carbonylation, and methanol conversion to formaldehyde—represents another class of generally highly exothermic reactions. Oxidation reactions in particular are usually highly exothermic. The exothermic nature of these reactions has led to many systems for these reactions incorporating cooling equipment into their design. Those skilled in the art routinely overcome the exothermic heat production with quench or heat exchange arrangements. Extensive teachings detail methods of indirectly exchanging heat between the reaction zone and a cooling medium. Indirect heat exchange refers to the transfer of heat from one fluid to another fluid across a common surface without intermixing of the fluids as normally occurs in quench systems. The art currently relies heavily on tube arrangements to contain the reactions and supply indirect contact with the cooling medium. The geometry of tubular reactors poses layout constraints that require large reactors and vast tube surfaces to achieve high heat transfer efficiencies.
Other process applications accomplish indirect heat exchange with thin plates that define channels. The channels alternately retain catalyst and reactants in one set of channels and a heat transfer fluid in adjacent channels for indirectly heating or cooling the reactants and catalysts. Heat exchange plates in these indirect heat exchange reactors can be flat or curved and may have surface variations such as corrugations to increase heat transfer between the heat transfer fluids and the reactants and catalysts. Many hydrocarbon conversion processes will operate more advantageously by maintaining a temperature profile that differs from that created by the heat of reaction. In many reactions, the most beneficial temperature profile will be obtained by maintaining substantially isothermal conditions. In some cases, a temperature profile directionally opposite to the temperature changes associated with the heat of reaction will provide the most beneficial conditions. For such reasons, it is generally known to contact reactants with a heat exchange medium in cross flow, co-current flow, or counter current flow arrangements. A specific arrangement for heat transfer and reactant channels that offers more complete temperature control can be found in U.S. Pat. No. 5,525,311, the contents of which are hereby incorporated by reference. Other useful plate arrangements for indirect heat transfer are disclosed in U.S. Pat. Nos. 5,130,106 and 5,405,586.
Isolating reactants from coolants at the inlets and outlets of plate exchanger arrangements leads to elaborate designs and intricate manufacturing procedures. Simplification of the fluid transfer at the inlets and outlets of plate exchanger improves the cost effectiveness and practicality of plate exchanger usage in many processes. Improved arrangements for injecting reactants at intermediate locations along the process flow path can also improve reactor performance in terms of selectivity and yields.
It is, therefore, an object of this invention to simplify a plate exchanger design for the indirect heat transfer and injection of reactants in reaction zone.
It is a further object of this invention to simplify the feed and recovery of reactants and heat exchange fluid from a heat exchange reactor that uses a channel arrangement.
BRIEF SUMMARY OF THE INVENTION
In broadest terms, this invention incorporates intermediate injection of process fluids into open chamber portions that circulate fluid from a plurality of heat exchange channels to another plurality of heat exchange channels to control process reaction conditions and reactant concentrations. A chamber communicates the heated channels and the reaction zone across common ends of the narrow channels while simultaneously mixing reactants the ends of the channels to provide simple transfer of fluids between different sets of channels. The chamber permits additional temperature control by the addition or removal of reactants, cooling fluids or other streams at an intermediate point in the complete channel flow paths. Insertion of additional chambers along the flow path of either the reaction or heated channels provides locations for more temperature adjustment and control.
Suitable channel arrangements may exchange heat directly across a common heat exchange surface or may use an intermediate heat transfer fluid to indirectly transfer heat from a cooling or heating zone to the reaction zone. In this manner the intermediate heat transfer fluid allows optimization of conditions for endothermic and exothermic reactions in different channels while simultaneously providing temperature adjustment control for differences in heat generation from the exothermic reaction and heat absorption from the endothermic reaction. For example, one arrangement of the intermediate heat transfer fluid may place the cooling zone and the reaction zone at different portions of common channel and may pass the intermediate fluid through adjacent channels to transfer heat out of reaction channels at one location and transfer heat back into the heated channels at a downstream channel location. In other arrangements, the intermediate channels and the reaction channels may lie in a parallel arrangement between the heated channels to adjust the temperature in the reaction channels through the heated channels.
Variation of the catalyst loading within the reaction channels and the addition of catalyst for endothermic reactions may satisfy different processing objectives. For example, short loading of catalyst in reaction channels can provide a space above or below the reaction zone for additional feed preheat or effluent cooling. Again, extending the heated channels can provide additional surface area for open channel heat exchange against the exiting reaction zone effluent or the incoming reactants.
Although usefull in any heat producing reaction or heat absorbing reaction, this invention finds its greatest benefit in exothermic reactions. As an example, process and reactor arrangements in accordance with this invention may be especially usefull for producing ethylene oxide. A particularly beneficial process application for this invention is in the production of phthalic anhydride (PA) by the oxidation of orthoxylene. The reaction apparatus feeds the orthoxylene feed to a distribution manifold that injects a controlled amount of orthoxylene in admixture with the air or other oxygen containing gas. Injection of the orthoxylene into the manifold prevents the presence of the orthoxylene and
Mulvaney, III Robert C.
Petri John A.
Romatier Jacques J. L.
Doroshenk Alexa A.
Johnson Jerry D.
Paschall James C.
Tolomei John G.
UOP LLC
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