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Process Intensification and Integration for Sustainable Design. Группа авторовЧитать онлайн книгу.

Process Intensification and Integration for Sustainable Design - Группа авторов


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H2O Endothermic CH4 + H2O → CO + 3H2 Catalytic Partial oxidation O2 Exothermic
Catalytic/non catalytic Dry reforming CO2 Endothermic CH4 + CO2 → 2CO + 2H2 Catalytic

      Although these processes may be used separately, combinations of two or more of the main reforming options have been proposed to enhance the overall performance of the reforming task. One such process is the autothermal reforming (ATR) in which the exothermic nature of the POX reforming is combined with the endothermic SR [21].

      In all of these reforming alternatives, energy and water usage and generation are key points to consider when selecting the appropriate technology. Studies regarding heat and mass integration potential for the SR, POX, and ATR options can be consulted in the work of Martínez et al. [21] and Gabriel et al. [22].

      For the synthesis of methanol, compression of the syngas obtained from the reforming stage is needed. Then, the compressed syngas is fed to a catalytic reactor in which the following reactions take place:

      The synthesis reactor operates at 83 bar and 260 °C. The outlet of the reactor is cooled and sent to a flash unit to separate the unreacted syngas and recirculate it. Additionally, a fraction of the recycled syngas is purged, with a potential use as fuel. The crude methanol obtained from the flash unit is purified using one or two distillation columns [23].

      It should also be noticed that the methanol synthesis reaction is exothermic; therefore, heat integration options may be considered to further enhance the environmental and economic performance of the process.

      Even when the MTO technology has been reported to be more profitable than the OCM option [26], the latter technology is less complex and avoids the need to transform the natural gas to intermediate products such as syngas. That provides an incentive to develop improvements to this technology in order to enhance its overall performance and profitability. Proposed ideas to achieve such improvements include the use of membranes in the CO2 separation system and modifications to the ethylene fractionation column to reduce heating and condenser duties [29,30].

      Benzene is an important starting molecule in the petrochemical industry. The production of benzene from shale gas was considered in Pérez‐Uresti et al. [31], and a process based on the direct methane aromatization (DMA) route was designed. In this process, methane is fed to a DMA reactor operating at 800 °C and atmospheric pressure. The main products of the reaction are benzene and hydrogen. The effluent from the DMA reactor is sent to a membrane unit to separate the hydrogen. Then, the remaining stream is cooled and compressed to be separated in a flash tank. The gas stream obtained from the flash separator is methane‐rich and is recycled to the DMA reactor. The liquid stream is fed to a distillation column where benzene is obtained as a top product. Although the DMA process competes with the traditional production routes based on catalytic reforming


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