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Chart Energy & Chemicals, a world leader in the design and manufacture of aluminum plate-fin heat exchangers, has now developed a new range of compact heat exchangers / micro-channel reactors. The common theme that is present in all of the new range of Chart E&C products is that they are manufactured from thin plates / shims and stacked to form assemblies that can resist the high loads required by the diffusion bonding process. This makes the new range particularly suitable for manufacturing in stainless steel, although they may also be produced as vacuum brazed aluminum assemblies.

MARBOND MICRO-CHANNEL REACTOR

The chemical process industry is dominated by "batch" processes operated in stirred tank reactors. While these traditional methods offer flexibility of operation, they have significant limitations, particularly when performing reactions that have the potential of rapidly achieving completion. The limitations include poor heat transfer, mixing intensity and distribution of reactants. These features can lead to extended cycle times, low product yield and purity, high energy costs and the risk of runaway reactions. The use of "continuous" operation equipment, or "Process Intensification" utilizing compact heat exchanger / micro-channel reactors that offer effective heat transfer, efficient mixing and low inventory, leads to inherent safety and efficiency of operation. "Marbond" offers these features.

"Marbond" utilizes compact multi-channel construction that incorporates high values of heat transfer surface area per unit volume, enhanced heat transfer coefficients and good mixing efficiency into a diffusion bonded construction that offers the capability of elevated temperature and pressure operation. Integral features facilitate controlled injection of reactants into process streams that are adjacent to cooling areas, enabling any excess heat to be effectively removed almost instantaneously, making for a nominally isothermal operation. Should the process be endothermic, then heat may be added in order to initiate the reaction and then maintain it at the optimum temperature for the process.

"Marbond" units are available in a wide range of sizes and have varied performance characteristics to suit specific applications. The normal material of construction is stainless steel (316) although other materials can be utilized if required.

CHART-PAK MICRO-CHANNEL REACTOR

Chart-Pak 1 (Where the streams are low-pressure liquids)

In the central portion of the unit is a series of parallel slots whose widths and lengths are specified in accordance with the designed catalyst optimum packing requirements. These are consistent throughout the flow length of the unit. Type 1 offers a simple rectangular construction for low-pressure applications where the coolant or heating stream is a liquid and the process and reactant streams are gases or liquids.

Chart-Pak 2 (For use as a packed bed catalytic reactor when all streams are gases)

Construction - Coolant and reactant streams The "pins" which join the hot stream separating plates to the cold stream separating plates accommodate the mechanical loads resulting from the internal pressure within the layer, provide heat conduction paths and promote turbulence for increased heat transfer. The pins are the full thickness of the shim and are arranged to be co-incident in each shim layer, but the joining ligaments are off-set in each shim layer.

The shims are stacked to provide the desired layer height. They are closed off with solid separating plates in the case of the coolant, and perforated in the case of the reactant.

The pins are provided by means of chemically etched shims that also contain the integral headers and side bars. The pins are held in position relative to each other by ligaments which are 1/2 the shim thickness.

Construction - Process stream The problem of providing open passageways into which the catalyst may be packed is solved by utilizing thicker plates. These have a series of slots which, when placed one on another, form open ended channels. If instead of solid separator plates, perforated versions are used, then fluid from an adjacent reactant stream may be precisely injected into the channels in order to control or enhance the reaction caused by the process fluid flowing through the packed catalyst.

Chart-Pak 3 (Where the streams are high-pressure liquids)

The construction is similar to that of Chart-Pak 1, but due to its geometry, it's capable of working at higher pressures. A layer construction system is adopted, but the layers are typically 2-6mm thick rather than 0.5mm. External to the flange diameter are the 4 lugs that are accessible when the unit is bolted in place in the pipe / duct installation.

CHART-KOTE MICRO-CHANNEL REACTOR

Another variation on the shim construction for a heat exchanger / reactor is covered by the trademark "Chart-Kote". The range combines a highly efficient heat transfer surface with a retention system for catalyst powder. The complex layers are assembled and diffusion bonded and then the catalyst powder is added. The Chart-Kote surface provides a perfect "key" for retention of the catalyst, providing excellent turbulence and heat transfer capability for the process fluid while it's flowing over the catalyst.

Applications:

• Reforming of methane, methanol and other hydrocarbons for the production of hydrogen for powering fuel cells
• Provides basis for reactor design for catalytic "clean up" of hydrogen rich streams for low temperature fuel cell applications
• Provides basis for design of gas-shift units that can be used in conjunction with a hydrocarbon reformer to increase the hydrogen content of the reformed fuel

CHART-FLO MICRO-CHANNEL REACTOR

Another variation on the shim construction for a heat exchanger is covered by the trademark "Chart-Flo". Chart-Flo provides a heat exchanger particularly suited for applications where "dirty fluids" are involved. The large process passageways contain the dirty fluid and readily allow flow without blockage occurring, while being surrounded by cooling channels.