Industrial processes have varied impacts on the environment. Depending on the intensity of these environmental impacts, these processes can be streamlined to ensure sustainability of resources within the industrial set up. (Ayres & Ayres, 2002)
Industrial ecology is an environmental agenda where industrial systems are modified to enhance sustainability of resources and limiting environmental degradation. (Young & Murray, 2005) It involves identifying energy flow and resources with a view to transforming the system from one with an open linear flow to one with a closed loop thus reducing wastes produced.
Contact process
In highlighting industrial ecology, this work focuses on the industrial manufacture of Sulphuric acid. It explores the material flows of the system and highlights the system design employed to ensure an effective industrial environment. Contact process is an industrial procedure in the manufacture of Sulphuric acid. The stages involved are:
- Combustion of Sulphur: this involves the combination of Sulphur with Oxygen to release Sulphur dioxide. This gas is then purified in the purification chamber to eliminate dust and other particles.
- Re-oxidation of Sulphur Dioxide: the pure Sulphur dioxide obtained from the oxidation of Sulphur is further oxidised to produce Sulphur trioxide. The Sulphur trioxide is an acidic gas responsible for “acid rain.” To prevent this phenomenon, the industrial ecologists have deduced a framework based on several engineering principles.
- Formation of oleum: the Sulphur trioxide obtained is further purified and mixed into a chamber containing concentrated Sulphuric acid. The compound formed, oleum, is then dissolved in water to form Sulphuric acid.
Industrial ecology principles in the contact process
The contact process poses immense challenges that have to be corrected.
Energy flows
Energy conservation and preservation is an aspect of environment the globe is currently grappling with. The contact process, in the interest of conserving energy, recycles heat energy obtained from the catalytic chamber. The heat is reused in the combustion of Sulphur. This essentially means that no heat energy is lost. It is thus important to design the system in such a way that the hot catalytic fumes are conducted back to the oxidation chamber for reuse.
Basing facts on the principle of Le Chatelier, the system has been designed in such a manner that the hot fumes obtained are also reused to support the whole system which requires humongous heat energy to yield high volumes of the acid – the process is endothermic. (Salzano, 2003)
Emissions gases
The process emits SO2 and SO3 which are considered acidic gases. Industrial ecology principles dictates the elimination of these stack gases forthwith, this is done through “scrubbing of the gases” hence reducing their effects on the environment. They are run through a stream of water dissolving them thus preventing their escape into the environment. The gases can also be neutralized with lime slurries before emission into the atmosphere. Nevertheless, the gases are treated with concentrated saline solutions -Ammonium Sulphate ,thus forming less toxic compounds.
SO2 is recycled into the oxidation chamber where it is further reacted with Oxygen to release SO3 which is dissolved forming oleum. The system thus reveals the recycling of the two gases.
Conclusion
Through industrial ecology, wastes in the process have been effectively reused reducing production cost. In addition, toxic products are recycled into the system making the process efficient (Kolstad, 2007)
References
Ayres, R. U. & Ayres, L. (2002). A handbook of industrial ecology. Cheltenham, U.K.: Edward Elgar Publishers.
Kolstad, C. D. (2000). Environmental economics. New York: Oxford University Press.
Salzano, M. (2003). The contact process on graphs. Rio de Janeiro: IMPA Publishers.
Young, D. & Murray, S. (2005). Industrial engineering. Chicago: Kaplan AEC Education publishers.