Design the Electrified Endothermic Steam Methane Reformer.
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:
1. Review the literature for the traditional equipment typically used for these tasks (high temperature endothermic steam methane reforming reactors.
2. 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.
3. 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.
4. 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.
5. Discuss issues you have identified related to the design, implementation, and adoption of large-scale electrified heating equipment for the process industries.
Solved by verified expertHere is a basic design for an EESMR:
Feed gas: The feed gas for the EESMR is methane (CH4) which is typically obtained from natural gas. The methane is first purified to remove any impurities such as sulfur compounds and carbon dioxide.
Preheating: The purified methane is then preheated to around 500-600°C before entering the reformer. This helps to reduce the amount of energy r
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Electrification: In an EESMR, a portion of the heat required for the endothermic reaction is supplied through electrical heating. This is typically done using resistive heating elements.
Steam: Water is added to the preheated methane to form steam (H2O). The steam is then mixed with the methane in a reactor chamber where the endothermic reaction takes place.
CH4 + H2O → CO + 3H2 (ΔH = +206 kJ/mol)
Heat exchange: As the endothermic reaction proceeds, the reactor chamber absorbs heat. This heat is then transferred to the incoming methane and steam mixture, which helps to preheat the feed gas.
Product separation: The output of the EESMR is a mixture of carbon monoxide (CO) and hydrogen gas (H2). This mixture is cooled and then passed through a series of separators to separate the CO and H2.
Purification: The separated hydrogen gas is then purified to remove any remaining impurities, such as carbon monoxide, water vapor, and other gases.
Compression: Finally, the purified hydrogen gas is compressed to the desired pressure for use in various applications.
Overall, an EESMR is a complex system that requires careful engineering and control. However, it offers an efficient and cost-effective way to produce large quantities of hydrogen gas for various industrial applications.
