A Study of an Oxy-coal Combustion with Wet recycle using CFD Modelling

Abstract Coal use presents challenges for reducing emissions of air pollutants and carbon dioxide (CO 2 ). In response to these challenges the research is focused on technologies that significantly reduce emissions of SO 2 , NO x , particulate matter (PM), and mercury (Hg), in order to develop toward "near zero emission" power plants. CO 2 emissions are gaining significant attention. Greater reduction of CO 2 emissions can be achieved by CO 2 capture and geological sequestration (CCS). One of the most important technologies for CCS is the oxy-combustion, which, due to its almost N 2 -free flue gases, reduces the CO 2 capture cost. The main aim of this work is to study, using the CFD commercial code FLUENT, the performances of pulverized coal combustion with exhaust gas recirculation, to evaluate the gas temperature and NO x emissions. Three dimensional steady-state simulations of a quarter of the IFRF no.1 furnace have been performed, for high-volatile bituminous coal. The Eddy Dissipation Model and Discrete Ordinates model have been used for turbulence-chemistry interaction and radiation respectively. The turbulence has been modeled using the standard k-ɛ model, with standard wall functions. A Lagrangian description has been used for the solid phase and empirical sub-models have been implemented for devolatilization and char burnout. Different combustion cases have been considered in several oxy-coal combustion environments, with different CO 2 /H 2 O concentrations in the gas recirculation. The effect of dry and wet recycle conditions on combustion characteristics has been considered. The results show the benefits in term of NO x emission in oxy-coal combustion. The temperature and emission profiles are influenced by the mixture of gas recycled, in fact the gas temperature and Thermal-NO x decrease when N 2 is replaced by CO 2 . The simulations were performed with the same mass flow rate of oxygen at inlet in order to evaluate also the effect of CO 2 and H 2 O

Numerical Investigation of Oxy-mild Combustion of Pulverized Coal in a Pilot Furnace☆

Abstract The Conventional coal-fired plants are large contributors to air pollution and greenhouse gas. The combustion generates pollutants such as oxides of sulphur, nitrogen, and carbon as well as fine organic and inorganic particulates. The new technologies able to reduce drastically the pollutant emissions and facilitate to use of coal in an environmentally more friendly way, are commonly known as clean coal technologies (CCT). In this context the CCS technologies play an important role to reduce the CO 2 emissions. The only form with truly zero CO 2 emissions in existence today is pre-combustion gas separation, namely, the combustion of fuel using oxygen instead of air. It is well known that burning pulverized coal in pure oxygen increases the flame temperatures, thus also increases NO x emissions. Therefore, to moderate the flame temperature and reduce NO x the oxygen is mixed with recycled flue gas (RFG). This approach to reduce CO 2 emissions is often called oxy-firing or oxy-fuel combustion. The purified CO 2 stream is then compressed and condensed to produce a manageable effluent of liquid CO 2 , which can be sequestered for storage (CCS) or for use in subsequent processes (CCR). MILD (Moderate or Intensive Low Dilution) or HiTAC (High Temperature Air Combustion) is an innovative combustion technology and probably the most important achievement of the combustion technology in recent years. In MILD combustion the reactions take place in almost the whole volume of the combustion chamber. This leads to temperature and species concentration fields uniform in the chamber. The fuel is oxidized in an environment that contains a substantial amount of inert gases (N 2 , CO 2 , H 2 O) and low oxygen concentrations. This is caused by an internal recirculation of combustion products generated by injecting preheated air jets into the combustion chamber with very high momentum, bringing the temperatures close to the combustion products temperature, reducing the NO x emissions. Because both technologies allow reductions of pollutant emissions, the aim of this work is to demonstrate the advantages of a combination of these two combustion technologies in order to analyze the temperature and specie concentrations field, the CO 2 and NO x emissions by means of CFD. The goal is understand if it is possible to combine the MILD combustion and OXY one in order to reduce the NO x emissions, and capture the CO 2

Numerical Simulation of MILD (Moderate or Intense Low-Oxygen Dilution) Combustion of Coal in a Furnace with Different Coal Gun Positions

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Analysis of a Trigeneration Plant under Transient Operating Conditions

Abstract A dynamic lumped-parameters model has been developed in order to analyse the performance of a combined cooling, heating and power (CCHP) plant during transient load variations. The plant allows the waste heat recovery from four Internal Combustion Engines (ICEs) to produce simultaneously refrigeration power for an absorption chiller, hot water for thermal user and electrical power. The heat recovery is realized through the exhaust gases, the jacket cooling water and the lubricant. The plant includes an auxiliary boiler, which maintains the water temperature levels to the values required by the absorption chiller, and a dry-cooler, which refrigerates the plant water before entering the internal combustion engines. Moreover, a three-way valve, which controls the water flow rate in order to satisfy both the refrigeration and the thermal loads, is considered. The simulations are carried out under thermal-drive and electric-drive strategy and the evaluation of the performance and time response of the CCHP apparatus are presented

Analysis of drug utilization and health care resource consumption in patients with psoriasis and psoriatic arthritis before and after treatment with biological therapies

To describe the therapeutic pathways of patients with psoriasis (PSO) and psoriatic arthritis (PsA) before and after treatment with biological therapies in a real-world setting and to determine the relative consumption of health care resources

Epidemiology, patient profile, and health care resource use for hepatitis C in Italy

The objectives of this study were to estimate the prevalence of Hepatitis C among six Italian Local Health Units (LHUs), to describe patient and antiviral drug characteristics, and to estimate the health care consumption rates and related costs for the management of patients affected by hepatitis C virus (HCV) infection by using data from routine clinical practice

Toward the development of direct emission yellow fiber lasers for biomedical applications

The paper presents the design and preliminary experimental validation of a fiber laser with direct emission in the yellow. The active material is a Dy-doped custom-made phosphate fiber, which is pumped by high-power blue diode lasers emitting at 450 nm. A suitable model has been developed to optimize the laser behavior and validated with a low-power version of the laser cavity with femtosecond written Bragg grating mirrors

Healthcare Resources Use in Patients with Human Immunodeficiency Virus (HIV). Real-World Evidence From Six Italian Local Health Units

AIM: The aim of the study was to evaluate healthcare resource use and related costs for the management of people living with Human Immunodeficiency Virus (PLWHIV) with and without comorbidities, and to compare the burden of comorbidities in PLWHIV to the general population.METHODS: An observational retrospective analysis, based on administrative and laboratory databases from 6 Italian Local Health Units (LHUs) was performed. Individuals receiving either an HIV treatment [Antiretroviral therapy (ART) – ATC code: J05A)], or with an HIV positive laboratory test result between January 1st, 2014 and December 31st, 2014 were included. The date of first ART prescription or positive test of HIV was used as the Index Date (ID). Patients enrolled were followed-up for all time available from the ID (follow-up period) and their clinical characteristics were investigated from one year prior to the ID (characterization period). Comorbidities were measured by using the Charlson Comorbidity Index; findings were compared with those of a sample of the general population with the same age and sex distribution (OsMed 2015). Healthcare resource use and related cost was evaluated during the follow-up period.RESULTS: 1,214 patients were included, 837 were PLWHIV without any comorbidities and 377 were PLWHIV with at least one comorbidity. Mean prevalence of prescriptions for treatment of comorbidities was higher in the HIV-infected population than in the Italian general population. The annual healthcare cost of managing HIV patients with comorbidities, was significantly higher than that for patients without comorbidities (€ 10,615 vs. € 8,665, p < 0.001).CONCLUSIONS: Study results showed that 30% of PLWHIV had at least one comorbidity. The cost of managing PLWHIV who have comorbidities was significantly higher than that of managing PLWHIV without comorbidities. Our data confirm that care and treatment services should be adapted to address the specific needs of people living with both HIV and comorbidities

Evaluation of Crude Oil Fouling Formation in a Heat Exchanger with Twisted Tape Inserts

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