Fatma H. Ashour

A hierarchical approach for the design improvements of an Organocat biorefinery

Lignocellulosic biomass has emerged as a potentially attractive renewable energy source. Processing technologies of such biomass, particularly its primary separation, still lack economic justification due to intense energy requirements. Establishing an economically viable and energy efficient biorefinery scheme is a significant challenge. In this work, a systematic approach is proposed for improving basic/existing biorefinery designs. This approach is based on enhancing the efficiency of mass and energy utilization through the use of a hierarchical design approach that involves mass and energy integration. The proposed procedure is applied to a novel biorefinery called Organocat to minimize its energy and mass consumption and total annualized cost. An improved heat exchanger network with minimum energy consumption of 4.5 MJ/kgdry biomass is designed. An optimal recycle network with zero fresh water usage and minimum waste discharge is also constructed, making the process more competitive and economically attractive.

Simulation of biomethanol production from green syngas through sustainable process design

Methanol is considered an alternative energy source due to its various applicability and high octane. As a fuel, it releases low emissions, and shows high performance and low risk of flammability. Egypt faces a high population growth rate, which implies an increase in the agricultural production. At present, the agriculture waste materials are burned leading to major environmental problems besides the loss of potential resources. This work builds a design methodology for producing biomethanol fuel from green syngas. The design methodology is based on rigorous model using the Aspen HYSYS® simulation software, and takes into account both economics and environment. As a case study, the design methodology is applied to design a plant that converts rice straw in Egypt into methanol. The raw materials for this process are selected from the major regions in Egypt producing rice straw with a total capacity of 1.6 million tons per year. These local regions are Kafr el Sheikh, Dakahlia and Sharkia governorates, located in northern part to Cairo. The methanol produced from the process is estimated to be around 156 thousand metric tons per annum. The process equipment capital costs are estimated to be 498 million dollars with total energy costs of 17 million dollars per annum. On the other hand, an annual revenue of 537 million dollars is obtained. The simulation model obtained in this study can be applied to any syngas coming from other gasification processes with different biomass feedstock. In addition, the model provides a robust basis for further studies of process integration leading to innovative and sustainable solutions to climatic and energy problems.

Integrated gasification combined cycle using Egyptian Maghara coal–rice straw feedstock

Rice straw is an agricultural waste that causes an annoying problem in Egypt if it is not well exploited. This study focuses on using this waste in power generation by co-gasification of Egyptian Maghara coal and rice straw blends using entrained flow gasifier technology. Aspen Plus was used to conduct a parametric study for investigation of the effect of changing the inputs to the gasifier on the produced gas composition. Three different input parameters, influencing the performance of the gasifier, including the percentage of coal to rice straw in the blend, the fraction of added water to the blend, and the mass percentage of oxygen with respect to the mass of the blend fed to the gasifier were analysed. Two alternative power production schemes (with and without carbon capturing) have been investigated. The obtained optimum feed conditions are: 40% coal in the feed blend, 20% water concentration in the feed slurry, and 80% oxygen with respect to the dry feed blend to the gasifier. For (10 0000 kg per hour) of the feed blend, the power generated was 270.1 MW in the case of non-carbon capturing, while in the case of carbon capturing, 263.52 MW was generated. Although it produces less power, applying carbon capturing techniques means handling less flue gas and thus using smaller gas turbines and results in more environmentally friendly emissions.

Modelling of Coal-biomass Blends Gasification and Power Plant Revamp Alternatives in Egypt’s Natural Gas Sector

Recently, there has been a growing research interest in the co-gasification of biomass with coal to produce syngas and electricity in a sustainable manner. Co-gasification technology do not only decrease potentially the exploitation of a significant amount of conventional coal resources, and thus lower greenhouse gases (GHG) emissions, but also boost the overall gasification process efficiency. In the present work, a rigorous simulation model of an entrained flow gasifier is developed using the Aspen Plus® software environment. The proposed simulation model is tested for an American coal and the model validation is performed in good agreement with practical data. The feedstocks used in the proposed gasifier model are dry Egyptian coal and a blend of an Egyptian coal and rice straw that is gathered locally. The proposed gasifier model mainly consists of three reactors. The first one is a yield reactor where the coal pyrolysis occurs, the second reactor is a stoichiometric reactor where the gasification reactions arise, and the third reactor is a Gibbs reactor where the water-gas and steam-methane reforming reactions take place. The influence of using a feed mixture of 90 % coal and 10 % rice straw on the gasifier efficiency is investigated. The developed model provides a robust basis for revamping of an existing Egyptian natural gas-based power plant to replace its standard fuel with a coal-rice straw blend, in case of low natural gas supply. The model is further employed to assess different revamping scenarios and alternatives within the natural gas power plant. For a dry blend of (90 % Egyptian coal and 10 % rice straw), the cold gas efficiency is estimated as 85.7 %, while for dry Egyptian it is calculated as 79.61 %. The revamped Egyptian natural gas power plant decreases the total annualized cost (TAC) by 52.7 % with respect to a new constructed integrated gasification combined cycle (IGCC) plant. Besides, the payback period decreases to 1.24 y rather than 12 y in case of the construction of a new IGCC power plant. (Less)