Sources and effects of uncertainty in chemical industry

Planning a network of integrated chemical production sites causes various problems. Due to the interdependency of the production processes, local disturbances at a certain level of a particular production site can affect the site s performance entirely or at least downstream (inter-site effect). Moreover, due to the interconnectedness of production sites in a chemical production network, such a local disturbance can spread out on the entire SC (intra-site effect). This fypicaUy feads to increased risk costs. The organization and central control of chemical production networks aims at hmiting the effects of such disturbances. 

Although the interdependency of supply risks is well-known in chemical production networks, it is difficult to quantify the effects arising from certain sources of uncertainties. This is caused by the complexity of production processes, the interconnectedness of the production network, and the limited capacities of commonly used logistical infrastructures. However, quantitative information is necessary to determine economically reasonable risk management decisions. 

Energy in chemical production sites comprises two main sources electric power and heat. Electric power is distributed via a cable network. Either a local power plant exists or the production site is supplied by an external partner. At a production site often a backup system exists to overcome short-falls of the primary source of electric power (at least for some time). Hence, disturbances due to a power short-fall occur quite seldom at chemical production sites. 

Heat is often distribnted as steam, which is centrally generated and distributed via heat transfer pipelines at different pressures. Especially the steam supply is a vulnerable process in each integrated chemical production. Typically, the set of local plants can be sub-divided into steam providers and consumers. Steam can result as a by-product (e g. of 

The local pipeline system of chemical production sites needs to be carefully supervised because disturbances immediately affect all associated plants. Possible disturbances are manifold. However, pipeline systems are exceptionally reliable from a technological point of view if they are carefully maintained with respect to corrosion and material weaknesses. Problems may occur from operating a plant under inappropriate conditions. For example, if pressure and/or temperature are not within the allowed ranges, chemical reactions may take place inside pipelines. This may affect the quality of the transported material and can lead to congestions or damages in the pipeline. 

---