Performance assessment and process optimization of a sulfur recovery unit: a real starting up plant.

Sulfur recovery units (SRU) have an important role in the industrial production of elemental sulfur from hydrogen sulfide, whereas the generated acidic gas emissions must be controlled and treated based on local and international environmental regulations. Herein, Aspen HYSYS V.11 with Sulsim software is used to simulate the industrial and treatment processes in a refinery plant in the Middle East. In the simulation models, in temperature, pressure, flow, energy, and gas emissions were monitored to predict any expected change that could occur during the industrial processes. The simulation models were validated by comparing the obtained data with actual industrial data, and the results showed low deviation values. The simulation results showed that the current process temperature conditions can work efficiently for sulfur production without causing any environmental consequences. Interestingly, the simulation results revealed that sulfur can be produced under the optimized temperature conditions (20° less than design temperatures) with a total amount of steam reduction by 1040.12 kg/h and without any negative impact on the environment. The steam reduction could have a great economic return, where an average cost of 7.6 $ per ton could be saved with a total estimated cost savings by 69,247.03 $ per year. The simulation revealed an inaccurate production capacity calculated by real data in the plant during the performance test guarantee (PTG) where the real data achieved around 1 ton/h higher capacity than the simulation result, with an overall recovery efficiency of 99.96%. Based on this significant result, a solution was raised, and the level transmitters were calibrated, then the test was repeated. The simulation models could be very useful for engineers to investigate and optimize the reaction conditions during the industrial process in sulfur production facilities. Hence, the engineers can utilize these models to recognize any potential problem, thereby providing effective and fast solutions. Additionally, the simulation models could participate in assessing the performance test guarantee (PTG) calculations provided by the contractor.

Exergy study of amine regeneration unit using diethanolamine in a refinery plant: A real start-up plant.

Refinery plants use diethanolamine (DEA) solutions for gas sweetening. The role of DEA is to absorb H2S from sour gas. Amine Regeneration Units (ARU) are used to regenerate the rich Amine with H2S from refinery units to Lean Amine. An ARU unit of a Middle Eastern refinery that began official production in 2020 was simulated using Aspen HYSYS V.11, and an exergy study was conducted on different equipment. Whereas energy is transformed from one form to another, the exergy is destroyed in an irreversible process. The total exergy was equal to the physical and chemical exergy. The physical exergy was calculated using HYSYS, and the chemical exergy was calculated using a series of equations embedded in Excel. The DEA concentration used was 25 wt%. The exergy destruction rates, destruction efficiency, and percentage share of destruction of each piece of equipment were calculated. The regenerator exhibited the highest destruction rate of 13459.73 kW, and a percentage share of 79.61% of the total destruction. The overall exergy efficiency was 99.7%. The DEA concentration decreased from 25% to 20% as a result of system losses during start-up. Therefore, a case study was conducted to test the effect of this decrease in the H2S concentration in the sweet gas, and no effect was observed. An exergy study was conducted using an DEA of 20%. The distribution of the equipment destruction did not change. The total destruction loss increased by 2057.08 kW. From the exergy and operation point of view, the best scenario was to use a 25% concentration, to prevent destruction losses and operation problems.

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.

Reducing CO2 emissions and energy consumption of heat-integrated distillation systems.

Distillation systems are energy and power intensive processes and contribute significantly to the greenhouse gases emissions (e.g. carbon dioxide). Reducing CO2 emissions is an absolute necessity and expensive challenge to the chemical process industries in orderto meetthe environmental targets as agreed in the Kyoto Protocol. A simple model for the calculation of CO2 emissions from heat-integrated distillation systems is introduced, considering typical process industry utility devices such as boilers, furnaces, and turbines. Furnaces and turbines consume large quantities of fuels to provide electricity and process heats. As a result, they produce considerable amounts of CO2 gas to the atmosphere. Boilers are necessary to supply steam for heating purposes; besides, they are also significant emissions contributors. The model is used in an optimization-based approach to optimize the process conditions of an existing crude oil atmospheric tower in order to reduce its CO2 emissions and energy demands. It is also applied to generate design options to reduce the emissions from a novel internally heat-integrated distillation column (HIDiC). A gas turbine can be integrated with these distillation systems for larger emissions reduction and further energy savings. Results show that existing crude oil installations can save up to 21% in energy and 22% in emissions, when the process conditions are optimized. Additionally, by integrating a gas turbine, the total emissions can be reduced further by 48%. Internal heat-integrated columns can be a good alternative to conventional heat pump and other energy intensive close boiling mixtures separations. Energy savings can reach up to 100% with respect to reboiler heat requirements. Emissions of these configurations are cut down by up to 83%, compared to conventional units, and by 36%, with respect to heat pump alternatives. Importantly, cost savings and more profit are gained in parallel to emissions minimization.