Typically the process consists of the cultivation of cells in bioreactors and the manufacture of product in production reactors. This process is composed of many steps, which are classified as either upstream or downstream.
The upstream process includes the preparation and supply of culture media, the cultivation of cells, and their extraction. Vessels and appliances for buffer preparation, supply, and transfer as well as filter and chromatography equipment are required at this stage.
In the downstream process, the product is purified through chromatographic methods. Filters, chromatography equipment, and supplies for buffer preparation and transfer are required at this stage.
To avoid contamination, cell culturing must be operated as a sterile process. All vessels and transfer lines involved have to be sterilized. After completion of one production batch, the entire plant is cleaned in an automated clean in place (CIP) process.
Each process step, whether physical (heating, cooling, liquid transfer, sterilization), chemical (cleaning), or biological (cultivation), demands optimum conditions to yield the highest possible efficiency. Sterilization, production and cleaning, dimensioning of the devices, and a sensible order of all process steps must be planned with precision. For all of these considerations, time and money are always decisive factors.
In order to determine the most favorable process conditions, energy balances that include the consumption of CIP-solutions, steam, cooling and heating fluids, and gases must be developed. Initially each process step is calculated separately for each vessel; subsequently, interactions of different vessels must be considered.