Distillation consumes large quantities of energy in the process industries. Process integration has proven to be very successful in reducing the energy costs for conventional distillation arrangements. However, the scope for integrating conventional distillation columns is often limited. These limitations can be overcome by using non-conventional column designs. If the full potential for thermal coupling was applied effectively throughout the European petroleum, petrochemical, and chemical industries, it would create enormous energy savings. Before the full potential of thermal coupling can be established across the European industry, further work is required: (i) to refine the design procedures to allow a wider range of designs to be analysed, (ii) to investigate theoretically and practically the hydraulic design of thermally coupled columns, (iii) to examine a range of generic processes (e.g. petroleum refining, ethylene production, etc.) to find suitable applications of the technology.
One of the most significant non-conventional arrangements involves "thermal coupling". Thermally coupled distillation column arrangements have been known for over 50 years. It has been established that when thermal coupling can be applied, energy savings of 30% are typical when compared with a conventional arrangement. In addition, the thermally coupled design, known as the dividing wall column, can save up to 30% of the capital cost compared with a conventional arrangement.
Although designers have been aware for many years of the improved energy efficiency possible with thermal coupling, such designs have until recently not been used. The sole exception is the recent use of the design by BASF. The reason for reluctance to use these designs is rooted in three reasons: lack of established design procedures, fear of control problems, reluctance to use untried technology.
The fluid mechanics of the fluid flow inside complex columns will be modelled with a finite element model. Design methods for the material and energy balance, hydraulic design and control will be developed and tested using simulation and pilot plant tests.
Expected Achievements and Exploitation
New design methods have recently been established which optimise the design for minimum energy consumption and allow initialisation of the rigorous simulation. Control has been studied theoretically using dynamic simulation and in a new pilot plant (0.3m diameter, 10.5m height). The control schemes studied so far indicate that the dividing wall column can indeed be successfully controlled.
As contracting and consulting companies are members of this team, a very good background will be available for continuation of the project inside THERMIE. It is already clear from the interest shown by various industrial companies, that the potential for the application of thermally coupled distillation columns for energy and capital savings is considerable. The results will be compiled into a technology package and offered under licence.
Funding SchemeCSC - Cost-sharing contracts
HA9 0EE Wembley