The chosen process determines the type and required sequence of the basic process operations. To illustrate a process, so-called basic flow diagrams are drawn up during the basic engineering phase and discussed for further coordination during the planning phase.
Among other things, the basic flow diagram defines the reactants and assigns them to the appropriate storage facilities. The reaction products, as well as the processing stages and their final storage, are also recorded in such a basic flow diagram and are therefore also part of process development. To achieve an optimal process design, the following steps are required in advance:
- Laboratory development (small-scale trials)
- Pilot plant reactor
- Pilot plant
- First large-scale plant
To minimise the time and material costs involved, DMT ENCOS also uses appropriate simulation programmes such as ASPEN during plant design to calculate the relevant basic process operations.
Optimisation as the core task of the process engineer
The design of a process plant is the responsibility of the process engineer. The aim is to design a plant in such a way that the capital and operating costs are in a balanced ratio, whilst at the same time meeting the required product specifications in terms of quantity and quality. To achieve this, material, mass and enthalpy balances are drawn up for both the individual process stages and the future plant as a whole.
At the interfaces – known as plant boundaries – these balances are used to further determine raw material and energy consumption, as well as product and waste quantities. Within the process plant, the balances determine the mass flows and the physical and chemical conditions that must be maintained. The results of the balances are then documented in the media data sheets.
The preparation of site plans and process flow diagrams is one of the core disciplines at DMT
Flowcharts are among the most important documents in basic engineering. They are drawn up at three levels of detail:
- Basic flow diagram
- Process Flow Diagram (PFD)
- Piping and Instrumentation Diagram (P&ID)
Whilst basic and process flow diagrams must be produced as part of basic engineering, the main work on detailed piping and instrumentation diagrams (P&IDs) only takes place in the subsequent stage (plant construction), known as detailed engineering. Customer specifications are provided for the preparation of the flow diagrams, or these are agreed between the designer and the operator. The process flow diagram serves to illustrate the process engineering concept and thus clearly represents the next level of detail above the basic flow diagram. All essential components can be found here:
- pumps, compressors, heat exchangers
- columns, vessels
- Pipework and conveying systems
- Measuring and control instruments
What does the materials concept encompass?
Before DMT can begin planning the main equipment, the materials to be used in the future process engineering must be determined and documented. The selected materials not only influence the design of the pipework and apparatus, but also their procurement costs.
Material selection is of particular importance here, as it must be ensured – in the context of warranty claims – that these materials can withstand the corresponding stresses caused by corrosion and wear over a long period of time. DMT’s engineers draw on many years of experience in the fields of strength, corrosion and wear behaviour. When defining the materials concept, process engineers must take the following points into account:
- Design pressures and temperatures
- Strength considerations
- Weldability of the intended material
- Manufacturing considerations
- Flexibility in the face of changes (sleeve adjustments, retrofitting)
