Your task is to design an example of electrically-heated process equipment. The electricallyheated equipment to be designed an electric furnace to conduct a
steam-methane-reforming reaction. In this case you will assume the availability of carbon-emissions-free electricity at conditions (phase, voltage) commonly
available in industrial settings in any amount needed. An explanation of case follows:
Case – Electric endothermic steam methane reformer:
There are a number of important high temperature endothermic reactions, for example, steam cracking of ethane to ethylene and steam methane reforming
to make hydrogen (steam in both cases is not entirely coincidental as steam also suppresses coke formation and plugging in high temperature reactions).
These reactions are conducted in nickel-chromium alloy tubes. In the case of steam methane reforming, the reaction is catalyzed with a heterogeneous
catalyst packed into the tubes. These tubes might be resistively heated by passing electric current through them or by wrapping resistance heating elements
around them, or them might be inductively heated. Typical temperature range 800-900C.
Specifically, design an electrically heated steam methane reforming (SMR) furnace capable of producing 10,000 Nm3/hr (Normal conditions: 0C, 1atm,
1.013bar) hydrogen prior to any water gas shift assuming complete methane conversion and selectivity. The endothermic reaction (206kJ/mol CH4) is to
occur in tubes packed with a nickel catalyst operating at 900C, 20bara, and a molar steam to carbon ratio of 3:1 with a gas residence time of 0.1s. These may
not be optimal SMR operating or performance conditions, but the point here is to design an electrically heated high temperature endothermic reactor. Electric
heating technologies you might consider include indirect resistance heating (passage of electricity through a tube containing the reforming catalyst, or
through an element arranged on the outside of a tube containing the reforming catalyst), and indirect inductive heating of the tube containing the reforming
catalyst. Or, you may use any other electrically-powered high temperature reactor-heating technology.
Please proceed as follows:
- Review the literature for the traditional equipment typically used for these tasks (high temperature endothermic steam methane reforming reactors.
- Review the literature for electric heating technologies that might be used instead. Since electrical heating has not much been used for chemical processes,
much of the literature may be for smaller scale applications such as packaged electric boilers, induction stoves, microwave ovens, etc. - Select an appropriate electric heating technology and a configuration for your electrically-heated equipment. If appropriate, extrapolate existing smaller
scale electrical heating technologies to the processing scale defined for that case. Carefully record all assumptions made in any technology extrapolations. - Design the specified electrically heated equipment in as much detail as you can. Include such details as shapes, arrangements, dimensions, materials of
construction, fabrication details, voltages, currents, safety considerations, subsystem details, etc. Explain why engineering configurations and details are
being proposed the way they are. Include sketches to illustrate your design details. Include engineering calculations to support your hypothesis that your
design will perform the task set forth for each case. Note and justify all assumptions. Your designs should be, to the degree possible, at the intermediate
“preliminary” level of detail, similar to the level of detail for distillation columns and heat exchangers in Chemical Enigneering Design 3rd Edition (Gavin
Towler) Chapters 17 and 19. - Discuss issues you have identified related to the design, implementation, and adoption of large-scale electrified heating equipment for the process
industries.
