Process Intensification and Integration for Sustainable Design. Группа авторов

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Process Intensification and Integration for Sustainable Design - Группа авторов


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petroleum feedstocks, it represents an attractive alternative given the low prices of natural gas.

      Another alternative for the production of on‐purpose propylene is the propane dehydrogenation process, in which a depropanizer column is used to separate C4+ compounds that may be present in the fresh material. The purified propane enters a cold box to refrigerate the effluent from the propylene production reactor. Then, the propane stream is mixed with hydrogen and sent to a fired‐heater before being fed to a fluidized catalyst bed reactor. The reaction is highly endothermic. The outlet stream of the reactor contains propylene, propane, light gases, ethane and ethylene, and some heavier hydrocarbons. The reactor effluent is cooled, compressed, and sent to a cool box where hydrogen is separated from the hydrocarbons. The liquid stream from the cold box is sent to a selective hydrogenation process (SHP) to further improve the production of propylene. The effluent from the SHP is fed to a deethanizer column to remove light gases. Finally, the remaining stream is fed to a C3‐splitter column to produce the propylene. The propane obtained at the bottom of the splitter column is recycled to the depropanizer column [32].

      These processes represent an excellent opportunity for the independent production of propylene instead of obtaining it as a byproduct of other processes.

      The incentive for shale gas monetization can also be viewed as an opportunity to develop intensified processes for shale gas transformation technologies. Recent efforts to design intensified processes have been observed. Process intensification is understood here as a search for more competitive process alternatives via the development of more compact flowsheets (i.e. with fewer pieces of equipment or smaller sizes of the same number of equipment units) and/or with a reduction on the consumption of basic resources (raw materials, energy) through more efficient designs.

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      Using these concepts, Lutze et al. [36] developed a methodology for process design of intensified processes, consisting of three stages. In the first one, a basic process flowsheet is synthesized. In the second stage, SPBBs are developed and a superstructure that contains all the possible tasks of the system is formulated. The problem is then solved as a mixed‐integer nonlinear programming (MINLP) model to obtain the intensified structure that minimizes a given objective function such as the total annual cost of the system. Babi et al. [34] applied an extended formulation of that model that included sustainability metrics to a case study dealing with the production of dimethyl carbonate. In the work by Castillo‐Landero et al. [37], such a methodology was taken as a basis, but instead of formulating an MINLP model to search for the optimal intensified configuration, a sequential approach with gradual intensification of the process was conducted until a final structure with a minimum number of equipment units was obtained. One advantage of this procedure is that one can assess individual levels of process intensification so that a structure that favors a given metric of interest can be selected.

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