Patent FR-2824755-A1 (FR)
Title: Modular reactor for an exothermic reaction with reaction and heat-extracting plates alternating in a sandwich, with channels for catalyst and reaction, and for exchange fluid respectively
Inventor: CZERNICHOWSKI ECZYSLOVO
IPC: B01J19/24
Filed: 2001-05-15
Abstract: Reaction plates (R) containing the catalyst and heat-bearing plates (C) to extract heat during the reaction and supply heat to initiate it are enclosed by load plates (F) connected together by several bolts enclosing the sandwich. The circulations of reactant, fluid containing products and heat-bearing fluid are controlled (for composition, flow rate, temperature, pressure.  Modular reactor with stacked plates, packed together closely in a compact sandwich to carry out an exothermic process such as the Fischer-Tropsch (FT) catalytic synthesis of liquid hydrocarbons by selective hydrogenation of CO by hydrogen. Each reaction plate has a length from inlet to outlet not greater than 3m. The plates are flat and parallel to each other, and contain elongated circular, rectangular or other section channels with the same section as no more than a 16 mm diameter tube. The channels are separated by dividers and open at each end at an inlet and an outlet. The channels are separated from the two faces by face plates of reduced thickness to allow heat exchange preventing the active catalyst filling each channel from overheating. The active catalyst particles in the channel are 3 mm or less and fill the whole length of the channel, resting on an exit mesh fixed in each channel. An inlet mesh at the top of each channel prevents particles from accidentally flowing through the inlet. The meshes are fine enough to hold the particles whilst allowing the unconverted fluid and products to circulate. The faceplates and dividers are designed to just reach 5 MPa at the operating temperature, knowing that each plate cannot reach this pressure outside the sandwich assembly. The body is metallic or other material with a thermal conduction an order of magnitude greater than that of the catalyst particles. The material is chemically inert with respect to the particles, the reactant gas and synthesis products such as water and hydrocarbons, and can withstand temperatures of up to 500  deg C. The reactor can be used as a module where between 2 and 20 reaction plates are assembled edge to edge so the assembled plate operates as a larger reaction plate. Each heat- bearing plate evacuates the energy produced by the exothermic reaction in the neighboring reaction plates to maintain a temperature constant within 1  deg C in the channels. The heat- bearing plates also assist the start-up of the reaction by carrying heat to the reaction plates. The plates are similar to the reaction plates: flat and parallel to each other extending from inlet to outlet. The channels are separated by dividers and faceplates, opening at inlet and outlet. Bends in the channels create turbulence and the channels are connected to means of supplying and extracting the fluid. The thicknesses of the channels, dividers and faceplates are just sufficient to withstand the temperature of the catalytic synthesis (380  deg C) whilst ensuring good heat exchange. The channels are completely filled with fluid and the heat-bearing plates are made of a chemically inert material like the reaction plates. The bolts holding the load plates together can be partially replaced with cables. Reaction and heat-bearing plates and their connections are designed so they can easily be replaced and the plate assembly is non-definitive. The channels in the reaction plates run vertically or within 1 radian of vertical and those in the heat-bearing plates run horizontally or within 1 radian of horizontal. Tens or hundreds of pairs of R and C plates can be stacked together to form a parallelepiped assembly several tens of meters long with the same height as the length of the plates and the same width as the plates or a multiple thereof in the case of modular assembly. The assembly does not need to be encased or pressurized and is open to the sky to make assembly, start-up and maintenance easier. The outside of the reactor can be covered with an insulating layer such as glass or mineral wool to reduce heat losses.