The safe design of computer controlled pipeless batch plants
High profit (low volume) products are very attractive economically, and are influencing the direction of manufacture towards product based batch processes. One new system which has a great deal of potential is a "pipeless" plant, in which the reactor moves to different areas of the plant where heating, agitation etc. takes place. There are obvious advantages in its use in providing a means of quickly responding to fast market changes while maintaining high product quality with reduced waste. The basic concept has been successfully demonstrated with several production plants already in operation, mainly in Japan. Nevertheless the safety issues associated with pipeless plants have not been dealt with. Three main areas of further work have been identified in the safe design of computer controlled pipeless batch plants: process, computer control, and scheduling safety. In essence it is a batch process that is carried out, and therefore entails all the safety issues associated with a batch process, such as the sharing of resources. As with all new processes, it is necessary to identify and eliminate as many hazards as possible at the design stage. Computers can introduce hazards as well as benefits. There is extensive use of computer control in automated pipeless plants, and the primary manner in which problems occur is through hardware and software failures. Possible hazards need to be identified and eliminated at the design stage, without losing the benefits of plant flexibility and speed of product changeover. Scheduling is usually concerned with optimum product output, and does not consider safety. One of the biggest problems with moving reactors is collisions. To overcome, or minimise the possibility of this problem, the plant layout and schedule require careful consideration. Simulation is a very useful tool for demonstrating the interaction between the two. The aim of this research is to develop an integrated approach to hazard identification and safety requirement specification. The results of which should be a methodology that allows the user to produce a safe design for an economically attractive pipeless plant for batch processes.