Chemical Engineering Innovation Exhibit – 2024 PART II & FINAL

INCREASING LIME PRODUCTION IN ERITREA (Hanna Biniam, Heran Alazar, Jonathan Asmelash, Samrawit Ghebremeskel)

This study tackles a crucial need for Eritrea’s growing industries — an increased production of quicklime (CaO). Quicklime is a versatile material used in diverse industrial sectors like construction, metallurgy, and chemicals. With worldwide demand on the rise, leading to an estimated production of 420 million tons globally, Eritrea seeks to optimize its own lime production. This research study focuses on the production of quicklime (CaO) from different regions in Eritrea through the calcination method and optimizing the process parameters such as temperature, particle size, and reaction time.

Currently, Eritrea’s lime production is limited, primarily serving the construction sector. As the mining activity in the country expands with large mining companies like Bisha and Zara, however, the local demand for lime is bigger than ever before. The objective of this research is to identify local source sites of lime, develop methods to produce high-quality lime in a controlled laboratory environment, design efficient lime production facilities based on the optimized process, and minimize energy consumption during the lime production process using advanced software tools like EXCEL, POLYMATH, and Generic Algorithm (GA).

The researchers conducted a total of 36 experiments to find the optimal setting for energy-efficient lime production. The optimal process identified operated at a temperature of 950⁰C, particle size of 2-5 millimeters, and reaction time of 1.5 hours. This configuration yielded a remarkable CaO production rate of 95.99% with minimal energy consumption. The findings underline the importance of identifying new local sources of limestone for production, designing efficient lime production plants based on the optimized process, and reducing reliance on imported lime. This could not only address the domestic demand but also position Eritrea as a potential lime exporter, boosting its industrial growth.

ENERGY RECOVERY FROM GEDEM CEMENT EMISSIONS (Samrawit Zerezghi, A. Ramesh Babu, Hanna Biniam)

This research investigates energy-saving opportunities in Eritrea’s cement industry, focusing on Gedem Cement Factory. Cement production is notoriously energy-intensive, requiring significant capital investment. The study explores potential methods to reduce energy consumption at Gedem, validate these models through testing, and assess the economic and environmental benefits of the proposed solutions.

Cement production involves several energy-intensive steps, including preparing raw materials, pulverizing coal, clinker calcination (burning), and grinding the final product. Traditionally, cement plants utilize rotary kilns with multi-stage cyclone preheaters. Modern plants typically consume 3 – 3.5 GJ/ton of electrical energy for clinker production. Dry process cement plants, like Gedem, can recover up to 40% of their total heat input from waste gas exiting the preheater and clinker cooler.

Gedem, Eritrea’s second cement plant, produces three types of cement, with a focus on Portland cement. Since its inception, the factory has faced challenges with maintaining production capacity due to limited energy availability and inefficient energy use. The research identifies two potential sources of waste heat recovery at Gedem. The first is the exhaust gas exiting the rotary kiln, which remains at a significant temperature (360⁰C) after preheating raw materials. The second source is hot air (280⁰C) expelled from the clinker cooler.

Utilizing waste heat recovery offers several advantages, including reducing thermal pollution, lowering overall pollutant emissions and decreasing CO2 emissions by minimizing fossil fuel consumption. Additionally, it significantly lowers the plant’s specific energy consumption.

The research proposes implementing a hybrid waste heat recovery (WHR) system at Gedem. This system would combine a WHR unit with an Organic Rankine Cycle (ORC) unit using R134a as the working fluid. This system has the potential to recover 2.745 MW of energy, generating approximately 19.764 GWh of electricity per year (assuming 300 operational days).

Preliminary economic analysis suggests potential annual savings of up to 3.294 million USD based on Eritrean electricity tariffs and the proposed system’s generation capacity. Additionally, the WHR system would contribute to a reduction of 5.027 million liters of oil consumption and mitigate CO2 emissions by an estimated 14,880 tons per year. This research offers a promising approach for improving energy sufficiency and environmental sustainability within Eritrea’s cement industry. If implemented, the proposed hybrid WHR system could significantly benefit Gedem Cement Factory by reducing operational costs and environmental impact.

PRODUCTION OF BIOCHAR FERTILIZERS FROM MANGROVE AND PROSOPIS JULIFLORA (Bersabiel Tsehaye, Furtuna Tekeste, Hermon Weldemichael, Mary Daniel, Osama Amir, Weini T.)

This research explores a promising alternative to conventional fertilizers for Eritrean farmers, who rely heavily on chemical options like DAP and Urea. While these fertilizers increase crop yields, their long-term use can harm the environment through groundwater contamination and soil degradation. This study proposes biochar, a charcoal-like substance produced from organic materials like Prosopis juliflora (a fast-growing tree) and mangrove trimmings, as a sustainable and effective organic fertilizer.

The researchers produced biochar using a process called pyrolysis, which involves heating plant material at high temperatures (350⁰C) in an oxygen-limited environment. Biochar was then added to the soil, either alone or with existing organic fertilizers, to assess its impact on plant growth. Salad plants were the test crops used to compare the effectiveness of biochar fertilizer with conventional options and a control group.

The P. juliflora biochar showed the most promising results, increasing both the weight and root length of the salad plants, whereas the mangrove biochar, though effective in increasing plant weight, had a varied impact on root length. The combination of biochar from P. juliflora and poultry manure achieved results comparable to DAP fertilizers in terms of plant weight and root growth. These findings suggest that biochar holds immense potential as a sustainable and effective fertilizer for Eritrean agriculture.

Biochar is believed to enhance water retention, nutrient storage capacity, and overall soil health. Unlike chemical fertilizers, biochar may also help reduce soil pollution and promote carbon sequestration. Further research can optimize its production methods and explore its impact on various crops, leading to a greener and more productive agricultural future.