Synthesis and parameter optimization of a combined sugar and ethanol production process integrated with a CHP system

Abstract

a b s t r a c tThe combined sugar and ethanol production process from sugar cane is a paradigmatic application for energy integration strategies because of the high number of hot and cold streams involved, the external hot utility requirement at two temperature levels for juice evaporation and crystallization, and the electricity demand for juice extraction by milling. These conditions make it convenient to combine the sugar-cane process with a CHP system fuelled by bagasse, the main by-product from juice extraction. The strategies, tools and expertise on energy integration developed separately by the research teams authoring this paper are applied here jointly to optimize the synthesis and the design parameters of the process and of the total site starting from the basic idea of dissociating the heat exchanger network design problem from the total site synthesis problem. At first the minimization of the external heat requirement for the process alone is pursued and results show that a one third reduction can be achieved by optimal heat integration. Then the use of the by-product bagasse for on-site power generation is considered and two bagasse-fuelled CHP systems are optimized along with some parts of the sugar and ethanol production process in order to obtain maximum total site net power. Results show a variety of interesting scenarios of combined sugar, ethanol and electricity production plants with considerably high electricity output.

Aplicação da análise envoltória de dados (AED) na avaliação da eficiência operacional relativa entre usinas de cana-de-açúcar no território brasileiro

“…A conversão da canade-açúcar em açúcar ou em etanol é composta por uma série de processos físicos e químicos que acontecem em subsistemas básicos que podem ser otimizados (MORANDIN et al, 2011).…”

Stripping of ethanol with CO2 in bubble columns: Effects of operating conditions and modeling

“…This cellular viability is essential in fermentation processes with yeast cell recycling, which depend on maintaining yeast cells alive until the end of the fermentation process, because they need to be reused over 6 to 8 months (Amorim et al, 2011). In order to be used as a fuel, the ethanol concentration must be at least 95 • GL, resulting in substantial energy consumption for purification of the fermentation product (Morandin et al, 2011), with industrial data indicating values of between 2.2 and 2.8 kg of vapor per liter of hydrated ethanol.…”

A novel MILP approach for simultaneous optimization of water and energy: Application to a Canadian softwood Kraft pulping mill

“…It was shown that reducing the crude syngas recovery ratio increases the quality of depleted gas that can be used as a hot utility or further recycled in the process. The same approach has been applied in liquid biofuel production (Tock et al, 2010), combined production of sugar and bioethanol (Morandin et al, 2011), hydrogen production from lignocellulosic biomass (Tock and Maréchal, 2012), and most recently, ammonia production (Tock et al, 2015).…”