The Development of Heat Substation for Drying Waste Heat Utilisation

The problem solution of waste heat utilization at the tobacco factory is considered in this work. The analysis of the possibility of waste heat utilization and appropriate calculations of plate heat exchangers were carried out. The method for multi component mixture condensation calculation is used. This allows obtaining optimal parameters for the working conditions of the heat exchangers according to the energy efficiency retrofit of industrial enterprises. The design of heat substation for waste heat utilisation was developed

Simultaneous optimisation of Multiple-Effect Evaporation Systems and Heat Exchanger Network

In recent work, a general superstructure and a Non-Linear Programming (NLP) model were presented for Multiple-Effect Evaporation Systems (MEESs). This NLP model was combined with a Heat Exchanger Network (HEN) model in order to simultaneously perform optimisation and heat integration of the overall system. The results of a forward-feed evaporation system integrated with hot and cold streams of the evaporation system as well as with the background process were presented. In this paper, the superstructure is extended by including multi-stage flash vessels for improving energy efficiency within the overall system. Additionally, various flow-patterns of heat-integrated MEES are studied. Also, trade-offs between energy and investment costs of heat-integrated MEES are explored for different numbers of evaporation effects in order to determine the optimum number of effects. The proposed Mixed-Integer Non-Linear Programming (MINLP) model of the combined MEES-HEN networks is implemented in a General Algebraic Modelling System (GAMS) and solved simultaneously using a two-step solution strategy. In the first step of the strategy, the NLP model of MEES is solved, providing an initialisation point for solving the MINLP model of the combined MEES-HEN network within the second step. A case study of a milk concentration process is used to illustrate the method. The results show that the forward feed flow-pattern with three evaporation effects is totally integrated with hot and cold process streams from the background process, and the system exhibits the minimum Total Annualised Cost (TAC)

SINTEZA TRAJNOSTNIH BIOPROCESOV Z UPORABO RAČUNALNIŠKO PODPRTE PROCESNE TEHNIKE

This doctoral dissertation, which consists of four substantive wholes, presents several syntheses of sustainable bioprocesses using computer-aided process engineering. In the first part the synthesis of different integrated processes of ethanol production from the entire corn plant is presented. The synthesis of different processes is in the second part further extended to the simplified and more comprehensive synthesis of bioproducts in the whole production supply chain network. Synthesis is based on the generic optimisation model of biomass production and supply chain networks. In the third part three methods for sustainable development assessment, suitable for multi-criteria optimisation, are presented: method of sustainability indexes, footprints and combined criteria, such as eco- and total profit. Methods are further upgraded with indirect effects in order to measure the unburdening the environment, associated with the use and replacement of environmentally-harmful products. Methods include the direct, indirect and total impacts on the environment. In the last part the methodology for reducing a large number of criteria within multi-objective optimisation to a small number of representative criteria is presented. This method is presented on the case of environmental footprints.V doktorski disertaciji, ki zajema 4 sklope, predstavljamo sintezo več trajnostnih bioprocesov z uporabo računalniško podprte procesne tehnike. V prvem delu je predstavljena sinteza različnih integriranih procesov proizvodnje etanola iz celotnega koruznega pridelka. Sinteza različnih procesov je nato v drugem delu razširjena na poenostavljeno in celovitejšo sintezo bioproduktov v celotni proizvodni mreži. Le-ta temelji na splošnem optimizacijskem modelu omrežja za proizvodnjo in dobavo biomase in biogoriv. V tretjem delu so predstavljene tri metode ocenjevanja trajnostnega razvoja primerne za večkriterijsko optimiranje, metoda trajnostnih indeksov, odtisov in kombinirani kriteriji, kot sta metoda eko- in celotnega dobička. Metode so nato nadgrajene tako, da upoštevajo tudi posredne okoljske vplive, povezane z rabo in zamenjavo okolju škodljivih produktov. Metode tako vključujejo neposredne, posredne in celotne vplive na okolje. V zadnjem delu je predstavljena metodologija za zmanjšanje večjega števila kriterijev pri večkriterijskem optimiranju na manjše število reprezentativnih kriterijev. Metoda je predstavljena na primeru okoljskih odtisov

Comparative study of hydrothermal decomposition of virgin and recycled polypropylene

Plastics are widely used due to their versatile properties and numerous applications. However, the proper management of plastic waste is a major challenge, even though it is recyclable. The process of repeated recycling can cause the quality of the material to decrease as unwanted contaminants and pollutants increase. This can affect the chemical recycling of plastics at the end of their life and the recovery of secondary products that can be used in other applications. In this study, the chemical degradation of virgin polypropylene (vPP) and recycled polypropylene (rPP) was investigated in supercritical water at a temperature of 450 °C and a reaction time of 15 to 240 min. The oil phase was the primary decomposition product and was obtained in high yield, which reached a maximum after 30 min of reaction time and was 96.9 % for vPP and 94.5 % for rPP. The results of our study show that there are some differences in the product composition depending on which material (vPP or rPP) is chemically recycled

A game theoretic approach for plastic life cycle assessment

Plastic production and its end-of-life management pose a significant environmental footprint. The mitigation strategies of the plastic industry are comparatively attainable than the other hard-to-abate sector. However, the involvement of different stakeholders is needed. The life cycle analysis proposed in this study allocated the environmental footprint to stakeholders based on the game theory concept. It addresses the limitation of previous approaches that do not guarantee the stakeholders from different stages will participate in the initiatives with the lowest net environmental footprint due to the dissatisfaction or imbalance in the allocated unburdening footprint (benefit) and burdening footprint. The applicability of the proposed approach is demonstrated through a plastic recycling case study. An allocation of 82 % of environmental benefit to the producer, 14 % to the manufacturer, and 4 % to the user are suggested to achieve efficiency (lowest external interference) and stable cooperation (participation in recycling). This work serves as an initial assessment in demonstrating the integration of the game theory concept in environmental footprint allocation or Life Cycle Assessment