Static Flowsheet Calculations

Spence_P&ID Grasp
Spence models can be easily entered as ‘drag and drop’ in graphical user interface GRASP


The power plant as a set of building blocks

Spence® is an open ended, static flowsheet simulator that is especially dedicated for efficient thermodynamic mass and heat balance calculations of thermal power plants. It supports thermodynamic and chemical engineers in their daily work. Spence is made by process engineers, for process engineers.

Spence: the flexible decision-support tool

Generating electricity at a power plant is a highly complex process. Every change to the plant’s design, or to the composition of the fuel, has implications. Especially at power plants where coal is combusted or gasified, biomass is co-fired, or CO2 is captured. Power producers want to get a detailed picture of the impact of process changes. Spence is a powerful simulation package that can be used to simulate how a power plant works and pin points the implications of changes in the process.

Spence is actually a toolbox; a collection of libraries, in which data about equipment, fuel properties, gases, particulates and mathematics are incorporated. If the input data change, for example, if a plant moves to partial-load operation or if the fuel composition changes, Spence works out the implications.

Spence provides power plant operators with more insight into the processes taking place in their installations. In contrast to many other packages, Spence isn’t just a black box where data goes in at one end and neatly packaged answers come out at the other, without you having any control over what happens in between.

Spence provides a sound basis for decision making in all sorts of situations. For example, take the case of co-firing of biomass. Co-firing is increasingly applied around the world. Spence is used in projects for clients in Canada, the United States, Britain,Ireland, and the Netherlands, who want to know what percentage of the fuel’s heat will be converted into electricity, or what temperature profile changes will take place in the boiler when co-firing 10 or 25 percent biomass, or even when fully converting from coal to biomass. If co-firing would result in boiler temperatures that exceed design values, it’s vital for a plant owner to know that in advance. Such information enables owners to make sound decisions and avoid costly experiences further down the line.


Development in a nutshell

Development has started in the late eighties of the previous century and the package is updated frequently to keep up with new technology (such as solar power plants). CerTa Veritas uses this software for system design studies, guarantee measurement support and operational support.

The software is able to calculate every type of power plant, ranging from waste incinerator to coal gasification power plants, even including carbon capture technologies


Spence is a flexible software package written in Delphi programming language, containing property, equipment, flowsheet and mathematical routines. Properties of water, gases and fuels are calculated in accordance with international recognized standards, such as ISO and ASME. The equipment routines cover the total scope of equipment used in power plants.

Example of graphical flow sheet output (click to enlarge)


  • Via the graphical user interface Grasp
  • Via typed input with use of the Delphi editor


  • Predefined or user defined graphs
  • Graphical user interface Grasp
  • Predefined or user defined tables.

Key Benefits

Example of water-steam cycle in T-s diagram
  • Tailor made programming
  • Flexible
  • Open ended (user can add their own libraries to Spence)
  • Posibility of sizing equipment on practical data
  • Automatic mass-and energy balance check
  • Graphical flow sheet output with process conditions (p, T, m, h) at all streams
  • Special graphs like T,s diagrams and Q-T-diagrams
  • Can be expanded to a condition monitoring system