The use of visualization for heat exchanger network synthesis, both grass-roots and retrofit, has a long history. Visualization is appealing to the user because it helps gain insight into the underlying problem. When coupled with user interaction, this insight generation can be enhanced. Furthermore, when the interaction includes access to an optimization procedure, the result is a tool that is appealing and has the potential to generate good results. This paper describes the implementation of an interactive visualization procedure for heat integrated process design. The visualization includes information about the underlying process responsible for the heating and cooling requirements which define the heat exchanger network synthesis problem. Furthermore, the data structures which underpin the visualization method provide a natural problem formulation for simulated annealing as an optimizer for the heat exchanger network structure. The combination of visualization, user interaction, and stochastic optimization results in a robust and easy to use tool for heat integrated process design.