The Effect of Variation in Cone Position Heigth on Raw Water Turbidity Removal in Sedimentation Unit Continuous Discharge Flow (CDF) Method as a New Method

Unit sedimentasi metode continuous discharges flow (CDF) adalah metode baru dalam menyisihkan kekeruhan yang menggunakan prinsip tangki bocor secara kontinu dan terkendali. Perubahan ketinggian posisi cone dari dasar zona pengendapan ke bagian atas, dapat memperkecil jarak antara sumber aliran buang akibat bocor yang berasal dari cone sebagai sumber gaya baru yang bekerja terhadap flok, dan pada akhirnya meningkatkan efisiensi penyisihan kekeruhan. Penelitian ini bertujuan untuk menganalisis efisiensi penyisihan kekeruhan air baku pada 3 variasi ketinggian posisi cone di zona pengendapan. Penelitian menggunakan reaktor skala laboratorium kapasitas 240 L/jam yang terdiri dari unit koagulasi terjunan, flokulasi baffle channel dan sedimentasi metode CDF. Unit sedimentasi metode CDF yang digunakan adalah CDF 6% dengan variasi ketinggian posisi cone 0 m, 0,33 m dan 0,66 m dari dasar zona pengendapan. Air baku yang digunakan adalah Sungai Batang Kuranji Kota Padang dengan kekeruhan 25,876 – 26,012 NTU dan tawas sebagai koagulan dalam proses koagulasi. Hasil penelitian menunjukkan efisiensi penyisihan kekeruhan pada ketinggian posisi cone 0 m, 0,33 m dan 0,66 m secara berurutan adalah sebesar 82,88%, 83,86% dan 84,60%. Ketinggian posisi cone 0,66 m dari dasar zona pengendapan adalah posisi optimum dengan efisiensi penyisihan kekeruhan 1,72% lebih besar dari posisi cone di dasar zona pengendapan, yaitu 0 m. Analisis pengaruh ketinggian posisi cone terhadap penyisihan kekeruhan menggunakan korelasi Rank Spearman, menunjukkan pengaruh yang sangat kuat, semakin tinggi posisi cone semakin besar efisiensi penyisihan. Bilangan Reynolds (NRe)dan bilangan Froude (NFr) pada aliran buang ini secara berurutan adalah 23,83 dan 9,33x10-4. ABSTRACTThe continuous discharges flow (CDF) sedimentation unit is a new method for removing turbidity using the principle of a continuous and controlled leaking tank. Changes in the height of the cone position from the bottom of the settling zone to the top, can reduce the distance between the exhaust flow sources due to leakage from the cone as a new force source acting on the floc, and ultimately increase the efficiency of turbidity removal. This study aims to analyze the efficiency of raw water turbidity removal at 3 variations in the height of the cone position in the settling zone. The study used a laboratory-scale reactor with a capacity of 240 L/hour consisting of a plunge coagulation unit, baffle channel flocculation, and CDF sedimentation method. The sedimentation unit for the CDF method used is 6% CDF with variations in the height of the cone position 0 m, 0.33 m, and 0.66 m from the bottom of the settling zone. The raw water used is Sungai Batang Kuranji, Padang City with a turbidity of 25.875 – 26.012 NTU and alum as a coagulant in the coagulation process. The results showed that the efficiency of removal of turbidity at the height of the cone 0 m, 0.33 m, and 0.66 m respectively was 82.88%, 83.86%, and 84.60%. The height of the cone position 0.66 m from the bottom of the settling zone is the optimum position with a turbidity removal efficiency of 1.72% greater than the cone position at the bottom of the settling zone, which is 0 m. Analysis of the effect of the height of the cone position on the removal of turbidity using Spearman's Rank correlation showed a very strong influence, the higher the cone position the greater the removal efficiency. Reynolds number (NRe) and Froude number (NFr) in this exhaust stream are 23.83 and 9.33x10-4, respectively.

Measurement of cycle-resolved engine-out soot concentration from a diesel-pilot assisted natural gas direct-injection compression-ignition engine

Exhaust-stream particulate matter (PM) emission from combustion sources such as internal combustion engines are typically characterized with modest temporal resolutions; however, in-cylinder investigations have demonstrated significant variability and the importance of individual cycles in transient PM emissions. Here, using a Fast Exhaust Nephelometer (FEN), a methodology is developed for measuring the cycle-specific PM concentration at the exhaust port of a single-cylinder research engine. The measured FEN light-scattering is converted to cycle-resolved soot mass concentration ([Formula: see text]), and used to characterize the variability of engine-out soot emission. To validate this method, exhaust-port FEN measurements are compared with diluted gravimetric PM mass and scanning mobility particle sizer (SMPS) measurements, resulting in close agreements with an overall root-mean-square deviation of better than 30%. It is noted that when PM is sampled downstream in the exhaust system, the particles are larger by 50–70 nm due to coagulation. The response time of the FEN was characterized using a “skip-firing” scheme, by enabling and disabling the fuel injection during otherwise steady-state operation. The average response time due to sample transfer and mixing times is 55 ms, well below the engine cycle period (100 ms) for the considered engine speeds, thus suitable for single-cycle measurements carried out in this work. Utilizing the fast-response capability of the FEN, it is observed that cycle-specific gross indicated mean effective pressure (GIMEP) and [Formula: see text] are negatively correlated ([Formula: see text]: 0.2–0.7), implying that cycles with lower GIMEP emit more soot. The physical causes of this association deserve further investigation, but are expected to be caused by local fuel-air mixing effects. The averaged exhaust-port [Formula: see text] is similar to the diluted gravimetric measurements, but the cycle-to-cycle variations can only be detected with the FEN. The methodology developed here will be used in future investigations to characterize PM emissions during transient engine operation, and to enable exhaust-stream PM measurements for optical engine experiments.

Are BBQs Significantly Polluting Air in Poland? A Simple Comparison of Barbecues vs. Domestic Stoves and Boilers Emissions

The study attempts to compare the total annual emissions of selected air pollutants emitted during occasional grilling and the emission of the same pollutants from small domestic heating installations. For this purpose, in the absence of any data on the emission of pollutants during grilling processes, tests were carried out consisting of measuring the concentration of air pollutants in exhaust streams from two types of grills (solid fuel grill powered by charcoal briquette and gas grill powered by liquid propane), using popularly prepared dishes (previously marinated meat and raw, seasoned mixed vegetables). The concentrations of PM2.5, CH4, CO, CO2, H2O, NH3, N2O, NO, NO2, SO2 were measured in the exhaust stream from both grills using a particulate matter (PM) measuring device and a portable spectrometer, separately while grilling the same portions of meat and vegetables. Then, considering the available data on Poles’ barbecue habits, the emissions that are released into the air during occasional grilling were estimated. The calculated emissions were compared with the data on emissions from domestic heating installations used in Poland. It has been shown that during grilling, as much as 2.30, 92.07, 4.11, 3.83, 2.96, and 9.81 Gg of PM2.5, CO, NOx, SO2, NH3, and CH4 may be released into the atmosphere in Poland, respectively. In the case of PM, the amount of the pollutant emitted to the air is over 100 times lower than the emissions caused by the operation of small heating installations. In the case of other pollutants, the differences are smaller. Nevertheless, emissions from grills should not be underestimated as, in certain periods of the year, these sources may be responsible for not meeting the air quality standards in selected areas of the country, and thus the excessive exposure of people to pollutants resulting in negative health consequences. Therefore, attention was paid to the legitimacy of abandoning the use of charcoal and charcoal briquette grills and replacing them with gas-powered grills or electric ones, not only due to the health benefits of food and lower human exposure, but also by the reason of ecological values.

Effects of Biodiesel Addition on the Physical Properties and Reactivity of the Exhaust Soot Particles from Diesel Engine

The present study investigated the effects of adding 20 vol.% biodiesel to petroleum diesel (to produce a mixture termed B20) on the physical properties and reactivity of the resulting exhaust soot particles. Tests were performed at different engine loads of a constant speed, and the soot particles from the combustion of B20 and petroleum diesel fuel (DF) were collected from the engine exhaust stream. Transmission electron microscopy and Raman spectroscopy were employed for the analysis of soot morphology and nanostructure. The thermogravimetric analysis was used to determine the oxidative reactivity of the soot. For both the DF and B20 soot, increased engine loads result in soot aggregates with more compact morphology and primary soot particles with larger size and more organized structure. Compared to the DF soot, the B20 aggregates have a slightly more compact morphology and smaller primary particle size. No appreciable differences are observed in nanostructure between the DF and B20 soot. The thermogravimetric analysis demonstrates that the B20 soot is associated with lower peak temperature, burnout temperature and apparent activation energy, suggesting that it is more reactive than the DF soot.

DILUTE CAUSTIC AND WATER COMPARISONS AS SOLVENTS IN THE REMOVAL OF ACIDIC GASES FROM COMBUSTION EXHAUST STREAM OF A BOILER.

This work focused on the comparative analyses between the use of dilute caustic with a composition of 1.84% and using water alone (pH=7) that have the potential to remove SO2 completely from the exhaust flue gas of a combustion system and H2S in the incomplete reaction scenario. Two reaction pathways were utilized for the study, the complete combustion pathway as well as the incomplete combustion pathway. ASPEN HYSYS 8.6, a process simulation software, was used to simulate conditions with PENG-ROBINSON utilized as the vapour-liquid equilibrium (VLE) data prediction tool of the software. For the complete combustion pathway, a complete removal of SO2 was achieved using caustic while with the same conditions, utilizing water as solvent achieved a reduction of 90%. For the incomplete combustion pathway, using caustic gave about 53% removal efficiency for H2S while the water only showed a poor 16% increase of H2S. The study recommended the use of the dilute caustic for the following reasons; it gave a better removal percentage than using water alone, the use of the caustic will not contribute to caustic corrosion because of the low composition of the dilute caustic that will be used in the absorber, the choice of the caustic was also observed to be economical. Keywords: Caustic, Absorption, Emission, Simulation, Combustion, Solvents.

Dilute caustic and water comparisons as solvents in the removal of acidic gases from combustion exhaust stream of a boiler

This work focused on the comparative analyses between the use of dilute caustic with a composition of 1.84% and using water alone (pH=7) that have the potential to remove SO2 completely from the exhaust flue gas of a combustion system and H2S in the incomplete reaction scenario. Two reaction pathways were utilized for the study, the complete combustion pathway as well as the incomplete combustion pathway. ASPEN HYSYS 8.6, a process simulation software, was used to simulate conditions with PENG-ROBINSON utilized as the vapour-liquid equilibrium (VLE) data prediction tool of the software. For the complete combustion pathway, a complete removal of SO2 was achieved using caustic while with the same conditions, utilizing water as solvent achieved a reduction of 90%. For the incomplete combustion pathway, using caustic gave about 53% removal efficiency for H2S while the water only showed a poor 16% increase of H2S. The study recommended the use of the dilute caustic for the following reasons; it gave a better removal percentage than using water alone, the use of the caustic will not contribute to caustic corrosion because of the low composition of the dilute caustic that will be used in the absorber, the choice of the caustic was also observed to be economical. Keywords: Caustic, Absorption, Emission, Simulation, Combustion, Solvents.

DILUTE CAUSTIC AND WATER COMPARISONS AS SOLVENTS IN THE REMOVAL OF ACIDIC GASES FROM COMBUSTION EXHAUST STREAM OF A BOILER.

This work focused on the comparative analyses between the use of dilute caustic with a composition of 1.84% and using water alone (pH=7) that have the potential to remove SO2 completely from the exhaust flue gas of a combustion system and H2S in the incomplete reaction scenario. Two reaction pathways were utilized for the study, the complete combustion pathway as well as the incomplete combustion pathway. ASPEN HYSYS 8.6, a process simulation software, was used to simulate conditions with PENG-ROBINSON utilized as the vapour-liquid equilibrium (VLE) data prediction tool of the software. For the complete combustion pathway, a complete removal of SO2 was achieved using caustic while with the same conditions, utilizing water as solvent achieved a reduction of 90%. For the incomplete combustion pathway, using caustic gave about 53% removal efficiency for H2S while the water only showed a poor 16% increase of H2S. The study recommended the use of the dilute caustic for the following reasons; it gave a better removal percentage than using water alone, the use of the caustic will not contribute to caustic corrosion because of the low composition of the dilute caustic that will be used in the absorber, the choice of the caustic was also observed to be economical. Keywords: Caustic, Absorption, Emission, Simulation, Combustion, Solvents.

Nonlinear model predictive control applied to multivariable thermal and chemical control of selective catalytic reduction aftertreatment

Manufacturers of diesel engines are under increasing pressure to meet progressively stricter NO x emission limits. A key NO x abatement technology is selective catalytic reduction in which ammonia, aided by a catalyst, reacts with NO x in the exhaust stream to produce nitrogen and water. The conversion efficiency is temperature dependent: at low temperature, reaction rates are temperature limited, resulting in suboptimal NO x removal, whereas at high temperatures, they are mass transfer limited. Maintaining sufficiently high temperature to allow maximal conversion is a challenge, particularly after cold start, as well as during conditions in which exhaust heat is insufficient, such as periods of low load or idling. In this work, a nonlinear model predictive controller simultaneously manages urea injection and power to an electric catalyst heater, in the presence of constraints.

Identification of damages in the inlet air duct of a diesel engine based on exhaust gas temperature measurements

The temperature of the exhaust gas of a diesel piston engine, measured in the characteristic control sections of its thermo-flow system, can be a valuable source of diagnostic information about the technical condition of the elements limiting the working spaces thus separated, including the turbocharging system, but also its fuel supply system and replacement of the medium. In standard marine engine measurement systems equipped with an impulse turbocharging system, the exhaust gas temperature is measured at the outlet of individual cylinders and before and after the turbocharger turbine, using traditional thermocouples with high measurement inertia (time constant of tenths of a second and more). This means that for further diagnostic analyses, the average value of the periodically changing temperature of the exhaust stream leaving individual engine cylinders, the exhaust stream in the collective duct feeding the turbine and the exhaust stream in the exhaust duct of the turbine is used. This article proposes a new approach to the issue of diagnostic informationiveness of the exhaust gas temperature of a diesel engine, extending its observations with the dynamics of changes in the duration of one working cycle. The aim of the tests carried out on the laboratory stand of Farymann Diesel engine type D10 was to determine the diagnostic relations between the loss of permeability of the inlet air channel filter baffle and selected standards of the quick-changing signal of the exhaust gas temperature. On the basis of the calculations carried out, the following dynamic features of the recorded signal were determined: maximum amplitude of instantaneous exhaust gas temperature values (peak-to-peak value), its rate of increase and decrease, and the specific enthalpy of exhaust gases within one engine work cycle. Comparative analysis of numerical data characterizing the recorded quick-changing exhaust gas temperature courses clearly indicates obvious thermodynamic and energy consequences of partial loss of flow capacity of the air channel supplying the combustion chamber of the test engine. A further development of the experimental test programme is foreseen in order to determine a diagnostic matrix to support the diagnostic inference about the technical condition of the diesel engine on the basis of measurements and analysis of the quick-changing exhaust gas temperature.