Process Intensification and Integration for Sustainable Design. Группа авторов

Чтение книги онлайн.

Figure 1.3 Basic flowsheet for ethylene production from shale/natural gas.

1.12 Potential Benefits and Tradeoffs Associated with Process Intensification

Although intensification opportunities for shale gas technologies remain to be explored, it is worthy of mention its potential benefits and possible tradeoffs based on the results from research and applications of intensification methodologies. First, it could be mentioned that a direct economic impact that would favor investment and operating costs could be observed. A notable example is the intensified process design developed by Eastman Chemicals for the production of 400 kT/yr of methyl acetate that transformed a flowsheet with 10 units (one reactor and nine separation columns) into a single reactive‐distillation piece of equipment. The resulting intensified process had 1/5 of capital investment and 1/5 of energy costs with respect to the original process [39]. One could also expect improvements in other factors such as carbon footprint and global warming metrics [37]. However, tradeoffs with other aspects such as process inherent safety and process controllability remain to be assessed. In an initial work to account for process inherent safety for a case study dealing with the intensification of an isoamyl acetate process, it was found that a partially intensified process could provide a better alternative in terms of inherent safety expectations with respect to a fully intensified process [40]. On the other hand, the effect of losing degrees of freedom for process control that arises from intensifying an original process and how it affects the process operability and controllability is an item that remains to be addressed.

1.13 Conclusions

      An analysis of shale gas availability and its potential implications to support a shale gas industry that expands its use as an energy source to include transformation processes into value‐added chemical products has been presented. Designs for shale gas transformation into valuable chemicals such as methanol and ethylene are examples of current efforts to produce higher value‐added molecules particularly valuable as precursors of important end products. The development of extraction technologies has provided the basis for the development of shale gas monetization strategies. It has been shown how the profitability of shale gas processes may be in conflict with other important considerations such as the process safety, which sets the incentive for the development of multi‐objective optimization formulations to obtain designs that offer the best compromises between such conflicting metrics. Another interesting challenge, in addition to the development of efficient and profitable shale gas flowsheets, lies in the design of intensified processes for flowsheets originally based on conventional reaction and separation units. Current intensification methodologies could be taken as a basis, with the challenge of its application for cases based on gas‐phase reactions that involve complex reaction mechanisms and different types of separation processes. The development of membrane‐based processes seems like a promising alternative in the search for innovative shale gas intensified processes.

References