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world pulppaper 87 a complex production system can be simplified on the display without losing the important parameters and their connections with each other. Figure 2 shows simulations made on request from a user. Initial values are fetched from an earlier prediction or simulation. Input data can be changed by the user before the simulation starts. In this example the paper machines maintenance stop is prolonged and a production stop in the TMP plant is planned. Based on these assumptions the operator will see the resulting pulp level changes in the storage tank. Depending on the needs of the mill in question the displays show many more parameters as well as their dependence on each other. A complex production system can be simplified on the display without losing the important parameters and their connections with each other. In the Hallsta case the process operators can see pulp and steam production storage tank levels and paper machine consumption of pulp and steam. The consequences of one parameter change somewhere in the production line are immediately shown on the display making it possible to decide on any action. Other mills might want to display other important connections between different process parts to facilitate decision making Kenneth Lundstrm points out. Some examples could be Predicting buffers of chemicals and raw materials based on current situation and planned production. Minimising unnecessary changes in digesters production speed if the current situation and predicted future situation is known. Comparisons can be done with the drying machines need. Optimising energy consumption by running only the most efficient refiners when predictions show that the pulp needed at the moment is enough. In the future we might add an Optimisation functionality into PSA allowing it to give advice on the most beneficial process situation for a certain point in time. During periods of high electricity cost or perhaps a planned maintenance shutdown of the pulp mill the system could give advice on pulp buffer levels at a certain time in order to be able to have enough pulp for the paper machines according to the production plan. In order to get the most out of the PSA system training of all process operators took place during autumn and winter Maria McGuinness continues. It was important that they learned how to use it not least the possibility to simulate ways of coping with changes planned or unplanned in paper production. It is of course easier when production runs normally and planned changes are known well in advance. But this system is also useful when unexpected problems on the paper machines occur as the results of different actions can be simulated giving a good basis for the right decision. It is also true to say that almost every process operator has been in the TMP plant for many years so they can draw upon their experience when analysing simulation results. Figure 2. In this case a simulation is done assuming a prolonged production stop on the paper machine and a production stop of the TMP line