Structural and thermodynamic analysis of the thermal technology scheme of pulp and paper production

Relevance. The complexity of the structure of enterprises in the pulp and paper industry is determined by the large number of elements in the thermal technology schemes of production, reverse flows, connections with the environment in the form of consumed fuel and energy resources and waste energy in the form of secondary energy resources. For such enterprises, there may be many options for improving energy efficiency with the inclusion of energy-saving equipment. Therefore, the use of a structural and thermodynamic approach to the analysis of thermal technology schemes is proposed to select an effective option. purpose. Development of an algorithm for structural and thermodynamic analysis, which makes it possible to overcome the ambiguity of the initial data and calculate reliable values of the parameters of external energy sources, data on which are often not available in pulp and paper industries, but are necessary to assess the thermodynamic efficiency of waste energy use.

Methods. To achieve this goal, a systematic approach is used using matrix analysis and Boolean algebra, the exergetic method of thermodynamic analysis, and software has been developed that combines these methods. results. For the thermal technology scheme of paper production, the optimal sequence of thermodynamic calculations with a minimum number of iterations/assumptions in the sections of the conditional flow gap of the scheme has been determined. As a result of the thermodynamic analysis, data were obtained on the thermal and exergetic efficiency of the elements of the thermal technology scheme of pulp and paper production, as well as data on flows, the use of which will ensure the organization of an optimal system for recycling secondary energy.

Conclusion. The developed software for structural and thermodynamic analysis was implemented to evaluate the thermodynamic efficiency of the thermal technology scheme of paper production. The minimum number of flows of the scheme has been revealed – 20 flows, the conditional break of which makes it possible to fully perform the thermodynamic calculation of the scheme with a minimum number of iterations and determine reliable values of the energy flow parameters. The results of the thermodynamic analysis showed that the lowest exergetic efficiency is for devices with such discharge flows as the heat of cooling of the upper product of the columns, exhaust air after the drying process in a paper machine, recycled water, and wastewater. Therefore, it is in such devices that the energy of the discharge streams of the greatest exergetic potential should be returned to increase the thermodynamic efficiency of the heat technology scheme as a whole.

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