Scale up: It is the migration of a process from laboratory scale to the bench scale, then to the pilot plant scale and finally to the commercial scale / industrial scale. In scale up, product and process development move in small steps from a lab scale to a commercial scale in order to reduce the risk of investment in the next step. A product is formed in grams on lab scale, in kilograms on bench scale, tens of kilograms to tons on pilot plant and tons to thousands of tons on a commercial scale. Scale up is used for market growth, introduction of new processes, modification of existing processes or reduction in making expensive errors in design and operation.
Design: Design of a reactor is to find the size of the reactor necessary to achieve a specified conversion. It gives us the idea of which type and size of reactor and method of operation we should employ for a given duty. Design information, both chemical and mechanical is used for the fabrication / construction of the reactor.