Main Operating Parameters Research Articles

A review of electro-Fenton and ultrasound processes: towards a novel integrated technology for wastewater treatment.

Nowadays, the presence of persistent dissolved pollutants in water has received increasing attention due to their toxic effects on living organisms. Considering the limitations of conventional wastewater treatment processes for the degradation of these compounds, advanced oxidation processes such as electro-Fenton and sono-chemical process, as well as their combination, appear as potentially effective options for the treatment of wastewater contaminated with bio-recalcitrant pollutants. In view of the importance of the development of processes using real effluents, this review aims to provide a comprehensive perspective of sono-electro-Fenton-related processes applied for real wastewater treatment. In the first section, the fundamentals and effectiveness of both homogeneous and heterogeneous electro-Fenton approaches for the treatment of real wastewater are presented. While the second part of this work describes the fundamentals of ultrasound-based processes, the last section focuses on the coupling of the two methods for real wastewater treatment and on the effect of the main operational parameters of the process. On the basis of the information presented, it is suggested that sono-electro-Fenton processes substantially increase the efficiency of the treatment as well as the biodegradability of the treated wastewater. The combined effect results from mass transfer improvement, electrode cleaning and activation, water electrolysis, and the electro-Fenton-induced production of hydroxyl radicals. The information presented in this work is expected to be useful for closing the gap between laboratory-scale assays and the development of novel wastewater technologies.

Selective Synthesis of a Gasoline Fraction from CO and H2 on a Co-SiO2/ZSM-5/Al2O3 Catalyst

This article reports on a simple method for producing high-octane gasoline from CO and H2 on a Co-Al2O3/SiO2/HZSM-5/Al2O3 hybrid catalyst. In the selected pressure range (0.5, 1.0, and 2.0 MPa), it was found that a decrease in pressure and an increase in temperature contribute to an increase in the content of branched hydrocarbons. The optimal technological parameters of the process were determined to ensure high selectivity and productivity for C5–C10 hydrocarbons: pressure—1.0 MPa, ratio H2/CO = 2, gas space velocity—1000 h−1, temperature—250 °C. The selectivity for the gasoline fraction is 65.2%, and the ratio of branched to linear hydrocarbons (iso/n index) is 2.3. Under the specified technological conditions, an experimental batch of gasoline fraction (1000 cm3) was produced at the pilot plant during 400 h of continuous operation. The main physicochemical and operational parameters of the experimental gasoline fraction of hydrocarbons have been determined. The octane number determined by the research method according to GOST R 52947-2019 is 78.5 units.

Performance characteristics of a compact self-circulating liquid desiccant air dehumidification system coupled with a heat pump: A comprehensive parametric study

Integration of a heat pump with a liquid desiccant system for air dehumidification has received growing attention in recent years in view of its more compact size and lower electricity consumption. This paper presents a compact combined heat pump and self-circulating liquid desiccant air dehumidification system targeted at small cooling load applications. The compactness lies in the integration of the dehumidifier and evaporator as well as the integration of the regenerator and condenser. Besides, the design of solution self-circulation (SSC) is intended for energy savings and the auxiliaries are employed to help achieve energy matching between the heat pump and the air dehumidification system. First, a comparative study is performed to identify the more energy efficient one of the two strategies for energy matching. Based on this, a thermodynamic model-based parametric study is conducted to investigate the effects of various influencing factors on the energy matching relationship and performance of the proposed system, as well as the energy-saving potential relative to the basic system without SSC. The results show that there exists an optimum solution self-circulation ratio (SCR) to achieve the maximum COP under a given condition. Basically, the proposed system with a proper SCR could yield a significant energy-saving effect regardless of the performance variations under studied operation conditions. It is found that a reduction of 29.68 % in energy consumption and an improvement of 42.20 % in COP are achieved under the ambient condition of 30 ℃ temperature and 20 g/kg humidity ratio. Furthermore, a correlation analysis is used to reveal the association strength and direction between any two main operation and performance parameters. Finally, the heat recovery is proved to effectively reduce the cooling coils load. This paper provides an in-depth understanding of the energy matching relationship and demonstrates the energy-saving performance benefiting from SSC for future practical applications of the proposed system.

Study on the working medium of high temperature heat pump suitable for industrial waste heat recovery

In order to find a high-temperature heat pump (HTHP) working medium suitable for industrial waste heat recovery, this paper theoretically analyzes the thermodynamic properties of six refrigerants, including the coefficient of performance (COP), condensation pressure, compression ratio, heating capacity, exhaust temperature, and compressor power consumption. Based on the theoretical analysis results, environmental effects and the temperature range of industrial waste heat, MC-1 can be considered as a suitable working medium for high-temperature water source heat pump. The thermodynamic performance of MC-1 was experimentally studied and compared with that of HFC245fa and F-1 refrigerants. The results show that when the outlet water temperature of the condenser changes from 65 to 110 ℃ and the temperature lift is 35 ℃, the coefficient of performance of MC-1 varies from 4.24 to 5.05, which is much higher than that of both HCFC245fa and F-1. When the outlet water temperature of the condenser varies from 95 to 100 ℃, the average coefficient of performance of MC-1 is 16.2% higher than F-1 and 18.0% higher than HCFC245fa. The relative deviation between the theoretical calculation results and the experimental results of the main thermodynamic performance parameters does not exceed 10%, indicating that the theoretical results are reliable. Therefore, MC-1 can be recommended as the working medium for high-temperature heat pump with a single-stage cycle.

Best management practices for minimizing undesired effects of thermal remediation and soil washing on soil properties. A review.

The use of remediated soils as end-of-life materials raises some challenges including policy and regulation, permits and specifications, technological limitations, knowledge and information, costs, as well as quality and performance associated with using them. Therefore, a set of procedures must be followed to preserve the quality and fundamental properties of soil during a remediation process. This study presented a comprehensive review regarding the fundamental impacts of thermal desorption (TD) and soil washing (SW) on soil characteristics. The effects of main operating parameters of TD and SW on the physical, chemical, and biological properties of soil were systematically reviewed. In TD, temperature has a more remarkable effect on physic-chemical and biological characteristics of soil than heating time. Therefore, decrease in temperature within a suitable range prevents unreversible changes on soil properties. In SW, more attention should be paid to extraction process of contaminants from soil particles. Using the right dosage and type of chelating agents, surfactants, solvents, and other additives can help to avoid problems with recovery or treatment using conventional methods. In addition, this review introduced a framework for implementing sustainable remediation approaches based on a holistic approach to best management practices (BMPs), which, besides reducing the risks associated with different pollutants, might provide new horizons for decreasing the unfavourable impacts of TD and SW on soil.

Development of magnetic flotation hybrid separation process for cleaner coal preparation

The magnetic flotation hybrid separation process, which combines column flotation and magnetic separation, was anticipated to beneficiate a representative coal sample acquired from the El-Maghara coal mine with a relatively high ash percentage of 27.21%. The system was designed to introduce a high gradient magnetic field to a flotation column to hinder the flotation of magnetic particles even if attached to flotation bubbles, improving the coal demineralization process and producing high quality coal. The Box-Behnken design and response surface methodology were employed to investigate and optimize the combined influence of various operating parameters on the process performance. The effects of the main operating parameters such as magnetic field strength, slurry circulation flow rate, air flow rate, collector dosage, and frother concentration were investigated. Ash percentage, combustible recovery, and separation efficiency were defined as process responses. Upgrading the coal sample under the optimum conditions of 1.2 T magnetic field strength, 1500 ml/min circulation flow rate, 11.64 ml/min air flow rate, 0.87 kg/ton diesel collector, and 42 ppm methyl isobutyl carbinol frother, the predicted and two confirmation experiments data were 7.78%, 7.89%, 7.71% ash percentages with maximum recoveries of 75.86%, 76.37%, 75.94%, and maximum separation efficiencies of 77.17%, 78.51%, 78.71% respectively.

Research on the Impact of Supplying the Air-Cooled D21A1 Engine with RME B100 Biodiesel on Its Operating Parameters

It is known that the use of alternative fuels leads to changes in the operating parameters of internal combustion engines, and the nature of the changes in most cases is not known. Therefore, the question of researching the main operating indicators of the internal combustion engine supplied with RME B100 biodiesel fuel is important, and the results will help to eliminate or reduce negative factors that can lead to the deterioration of the operational and technical indicators of the internal combustion engine. The purpose of the research was to develop an experimental research facility using appropriate equipment and to study the main operational and technical parameters of the air-cooled D21A1 diesel engine on RME B100 biodiesel fuel. To reach the goal, the following tasks were formulated: the development of a test facility and research on the main technical and operational performance indicators of the D21A1 diesel engine on RME B100 biodiesel fuel. The authors’ previous research results were applied in the setting of the D21A1 test engine in the process of RME B100 biodiesel research; namely, to achieve maximum fuel combustion efficiency, the injection moment was increased by 6°. The results ensured the maximum efficiency of using RME B100 biodiesel in engines without making changes to the design of the latter. System analysis and the comparison method were used during the research. In the process of using RME B100 biodiesel fuel on the air-cooled D21A1 engine, we found a decrease in engine torque of 6.5%; a decrease in effective power of 6.7%; a growth in specific effective fuel consumption of up to 22.3%; and an increase in hourly fuel consumption of 14.1%. This is because the use of RME B100 fuel requires changes in the engine design that improve the mixture formation process.

Thermal-hydraulic characterization of R513A during flow boiling inside a 6.0 mm horizontal tube, comparison with R134a and development of a new correlation

This paper presents two-phase heat transfer coefficient and pressure drop data of refrigerant R513A, a new azeotropic mixture conceived as possible alternative to R134a for medium temperature small-size refrigeration systems. All the experiments were performed in a commercial horizontal stainless-steel tube having an internal diameter of 6.0 mm and an outer diameter of 8.0 mm. The channel heating was obtained through DC current and Joule effect. The effect of the main operating parameters in terms of mass flux (from 150 to 500 kg/m2s), heat flux (from 5.0 to 40 kW/m2), saturation temperature (from 30 to 50 °C) and vapor quality (from the onset of boiling up to the dry-out occurrence) was analyzed and discussed for the heat transfer coefficient values, finding that both convective and nucleate boiling were significant contributions. The same ranges of mass flux and saturation temperature were also applied to frictional pressure gradient trends with vapor quality, taken in adiabatic conditions. The thermo-hydraulic performances were then compared with those of R134a, obtaining lower heat transfer coefficients and very similar pressure gradients. Finally, the collected experiments were assessed with values predicted from the most quoted correlations available in literature. A new composite method for nucleate-dominant or convective-dominant mechanisms was proposed for the evaluation of the heat transfer coefficient, with a mean absolute error of 25.3%, whereas the frictional pressure gradient values were well predicted with the Friedel correlation, that provides a mean absolute error of 13.8%.

Development of a New Type of Electrochemical Reactor for Low Temperature Lime and Cement Production

The cement industry is responsible for more than 8% of the global CO2 emissions, making it one of the largest contributors to global warming. Two-thirds of these emissions are coming from unavoidable process gases caused by the calcination reaction of limestone (CaCO3). The remaining emissions are mainly coming from the combustion of fossil fuels. Due to the high temperature requirement (≈1500°C), direct electrification is difficult to consider. For these two reasons, the cement industry is therefore known as a challenging sector to decarbonize.A new electrochemical pathway for cement production has gained prominence in the scientific literature in recent years [1]. This technology has the potential to electrify the cement and lime production while producing at the same time valuable gases (O2, CO2, H2). It is based on a new type of hybrid electrolyser capable of working with solid, liquid and gaseous phases. Thanks to the acidity generated by water oxidation at the anode, the solid limestone feed, precursor of cement, is being dissolved. This dissolution produces pure CO2 which is mixed with pure O2 generated by electrolysis and which is easily captured for later use. The calcium ions are then migrating towards the cathode under the effect of the electric field. The OH- hydroxyl ions, produced at the cathode by water reduction, meet the calcium ions to form the final solid product, hydrated lime (Ca(OH)2). This lime can be used as such or converted into cement by additional steps.In this research, a laboratory-scale setup has been developed to study the feasibility of such a process. Different geometries have been tested and the main operational parameters affecting the different steps of the process have been investigated. Our results show first of all the formation and stabilization of a pH gradient within the electrolyser, which allows at the same time for the complete dissolution of CaCO3 in the acidic anodic environment while producing a white precipitate of Ca(OH)2 at the cathode. The setup also presents ideal faradaic efficiencies when using an IrO2 coated titanium anode and a nickel cathode in a 1M NaClO4 electrolyte. Alternative electrode materials, including a 316L stainless steel anode and an Inconel 718 cathode, have been considered as well. Finally, it was shown that the energetic efficiency can be further improved by pushing the kinetics of the dissolution and precipitation reactions through increasing the mobility of calcium ions, using Ca-based electrolytes, like Ca(ClO4)2. Based on our results, all the elementary concepts behind the hybrid electrolyser have been established, and a first blueprint of a continuous industrial process will be proposed.[1] - L. D. Ellis, et al. (2019). Toward electrochemical synthesis of cement—An electrolyzer-based process for decarbonating CaCO3 while producing useful gas streams. PNAS , 117, 12584-12591. Figure 1

Removal Efficiency and Adsorption Kinetics of Methyl Orange from Wastewater by Commercial Activated Carbon

This research investigates commercial activated carbon (AC) potential to remove methyl orange (MO) dye removal from aqueous solution using a batch process. The AC material was characterized using FTIR spectroscopy and SEM analysis. The effect of the main operating parameters, such as the pH, adsorbent dosage, contact time, and initial dye concentration, was studied. MO removal could be accomplished within 30 min at a pH value of 3. The calculated maximum MO adsorption capacity onto activated carbon was 129.3 mg/g, while the removal efficiency was 97.8%. Adsorption results were analyzed by studying the Langmuir and Freundlich isotherm models. The MO adsorption data on activated carbon were better explained by the Langmuir isotherm than by the Freundlich isotherm. The pseudo-second-order kinetic model may have had an effect on the MO dye adsorption on AC material. This research showed that the commercial activated carbon can be used as an effective sorbent for MO removal from wastewater sample. Moreover, the AC material has good reusability and practical utilization capacities.

A novel integration of plasma gasification melting process with direct carbon fuel cell

As municipal solid waste (MSW) is a low-cost, available, and basically renewable source, energy recovery from MSW is a beneficial technique for reducing fossil fuel usage while also lowering MSW disposal challenges. The current study proposes a novel scheme consisting of plasma gasification melting (PGM) process and direct carbon fuel cell (DCFC) system for converting MSW into high-quality syngas and power. Plasma air and high-temperature steam are employed in the process as gasification agents. The DCFC runs on the pyrolysis char, which is a carbon-rich source and is extracted during the PGM process and sent to the DCFC. The process is simulated in Aspen Plus, and a computational model for estimating the DCFC's output voltage and power is developed in MATLAB. Effects of main operating parameters, including equivalence ratio, steam to biomass ratio, plasma energy ratio, char separation fraction, and fuel cell operating temperature on the system's performance indicators, namely syngas composition, syngas lower heating value, syngas yield, gasification temperature, overall efficiency, and DCFC power output were investigated. By increasing the char separation fraction, more pyrolysis char was extracted and forwarded to the DCFC, which leads to less amount of char entering the gasification section and higher power output through the DCFC. Keeping other parameters constant, at a fuel cell operating temperature of 923 K, the optimal value for char extraction fraction was 0.15, resulting in a 79.5% overall efficiency.

A hybrid system to predict brain stroke using a combined feature selection and classifier

BackgroundBrain stroke is a serious health issue that requires timely and accurate prediction for effective treatment and prevention. This study described a hybrid system that used the best feature selection method and classifier to predict brain stroke. MethodsThe Stroke Prediction Dataset from Kaggle was used for this study. Synthetic minority over-sampling technique (SMOTE) analysis was used to accomplish class balancing. Accuracy, sensitivity, specificity, precision, and the F-Measure were the main performance parameters considered for investigation. To determine the best combination for predicting brain stroke, the performance of five classifiers, Naïve Bayes (NB), support vector machine (SVM), random forest (RF), adaptive boosting (Adaboost), and extreme gradient boosting (XGBoost), was compared along with three feature selection techniques, mutual information (MI), Pearson correlation (PC), and feature importance (FI). The performance parameters were assessed using k-fold cross-validation. ResultsThe hybrid system proposed in this study identified a reduced set of features that were able to effectively predict brain stroke. FI provided a feature reduction ratio of 36.3%. The most successful hybrid system for predicting brain stroke used FI as the feature selection technique and RF as the classifier, achieving an accuracy of 97.17%. ConclusionThe proposed system predicted brain stroke with high accuracy. These findings could be used to inform the early detection and prevention of brain stroke, allowing healthcare professionals to provide timely and targeted care to at-risk patients.

A Review of High-Power Semiconductor Optical Amplifiers in the 1550 nm Band.

The 1550 nm band semiconductor optical amplifier (SOA) has great potential for applications such as optical communication. Its wide-gain bandwidth is helpful in expanding the bandwidth resources of optical communication, thereby increasing total capacity transmitted over the fiber. Its relatively low cost and ease of integration also make it a high-performance amplifier of choice for LiDAR applications. In recent years, with the rapid development of quantum-well (QW) material systems, SOAs have gradually overcome the shortcomings of polarization sensitivity and high noise. The research on quantum-dot (QD) materials has further improved the noise characteristics and transmission loss of SOAs. The design of special waveguide structures-such as plate-coupled optical waveguide amplifiers and tapered amplifiers-has also increased the saturation output power of SOAs. The maximum gain of the SOA has been reported to be more than 21 dB. The maximum saturation output power has been reported to be more than 34.7 dBm. The maximum 3 dB gain bandwidth has been reported to be more than 120 nm, the lowest noise figure has been reported to be less than 4 dB, and the lowest polarization-dependent gain has been reported to be 0.1 dB. This study focuses on the improvement and enhancement of the main performance parameters of high-power SOAs in the 1550 nm band and introduces the performance parameters, the research progress of high-power SOAs in the 1550 nm band, and the development and application status of SOAs. Finally, the development trends and prospects of high-power SOAs in the 1550 nm band are summarized.

A simulation-based software to support the real-time operational parameters selection of tunnel boring machines

With the fact that the main operational parameters of the construction process in mechanized tunneling are currently selected based on monitoring data and engineering experience without exploiting the advantages of computer methods, the focus of this work is to develop a simulation-based real-time assistant system to support the selection of operational parameters. The choice of an appropriate set of these parameters (i.e., the face support pressure, the grouting pressure, and the advance speed) during the operation of tunnel boring machines (TBM) is determined by evaluating different tunneling-induced soil-structure interactions such as the surface settlement, the associated risks on existing structures and the tunnel lining behavior. To evaluate soil-structure behavior, an advanced process-oriented numerical simulation model based on the finite cell method is utilized. To enable the real-time prediction capability of the simulation model for a practical application during the advancement of TBMs, surrogate models based on the Proper Orthogonal Decomposition and Radial Basis Functions (POD-RBF) are adopted. The proposed approach is demonstrated through several synthetic numerical examples inspired by the data of real tunnel projects. The developed methods are integrated into a user-friendly application called SMART to serve as a support platform for tunnel engineers at construction sites. Corresponding to each user adjustment of the input parameters, i.e., each TBM driving scenario, approximately two million outputs of soil-structure interactions are quickly predicted and visualized in seconds, which can provide the site engineers with a rough estimation of the impacts of the chosen scenario on structural responses of the tunnel and above ground structures.

Combustion of LPG / DME gas mixtures in an SI engine with correction of the ignition advance angle

The paper presents the results of tests on a SI engine fueled with an LPG/DME blends of various composition. A number of experimental studies and calculations using a mathematical model were carried out to examine the suitability of this fuel. These tests allowed for the analysis of the changes taking place in the combustion process and the assessment of the main operating parameters of the engine. The results of the analysis of the combustion process make it possible to observe how the heat is released and how the indicated pressure changes, depending on the share of DME in the fuel mixture. The scope of the tests performed included engine and vehicle tests on a chassis dynamometer and a series of simulation tests conducted on the basis of the obtained results. The engine was powered by an LPG/DME fuel mixture with different proportions of components. The share of DME ranged from 0% to 30% of the fuel mass. The obtained results reflect the operation of the engine in the full load range and selected rotational speeds. Measurement series were made for different settings of the ignition advance angle. Based on the obtained results, a corrected map of the ignition advance angle was developed. The obtained results confirm the usefulness of using the LPG/DME mixture to power the SI engine.

Conceptual design of an innovative flexible and controllable Solar ORC cogeneration system for operating in remote areas

The instantaneous variations in environmental conditions such as solar irradiance, ambient air temperature, and wind speed may significantly affect the performance of a solar ORC system. Thus, designing a system that would be flexible, and capable of responding to any user demands despite the variations in environmental conditions is an important issue, particularly for applications in remote areas. A solar ORC system for producing electricity, freshwater, and high-temperature heating energy is introduced. The system is flexible enough to produce the desired amount of electricity and freshwater. It is achieved without changing the main operating parameters or using auxiliary equipment. The instantaneous performance of the system is investigated based on the thermodynamic models. Two integral (I) controllers are used to adjust two streams, X1 and X2, for controlling the amount of user demands in terms of electricity and freshwater. The performance and flexibility of the system in different environmental conditions are evaluated by considering three scenarios for two typical days, July 17 and January 08 at Zahedan City. As shown, the system responds well and fast to environmental conditions to meet the user’s demands. The present results show that such a system can practically and easily response to the community needs in terms of freshwater and electricity.

An intelligent method for TBM surrounding rock classification based on time series segmentation of rock-machine interaction data

Accurate, continuous real-time perception of surrounding rock conditions on the tunnel boring machine (TBM) tunnel face provides particularly important prior information to ensure safe, economic, and efficient tunneling. This study presents an intelligent method for assessing the TBM surrounding rock conditions using a combination of time series segmentation and a deep clustering model (SSAE-FCM). In data preprocessing, fifteen operational parameters were selected as input features. And an adaptive piecewise constant approximation method was employed for the segmentation and compression of stable phase data. Then, a total of 69,214 data samples that can characterize the stable rock-machine interaction were obtained to construct a dataset. Thereafter, the SSAE-FCM model was established and trained to classify the surrounding rock conditions into four clusters. The distribution result of the main operational parameters and composite indexes (TPI, FPI, and SE) within these clusters demonstrated that the classification results are compatible with rock-machine interaction in engineering practice. Additionally, the rock mass assessment performance of the classification results was compared to BQ classification in terms of various rock mass parameters (UCS, Jv), fault sections, and collapse sections. These results indicate that the proposed classification method accurately reflects the stability and boreability of rock mass and is more sensitive to unfavorable geology than the BQ classification. From the three clustering evaluation indexes (SC, CHI, and DBI) perspective, SSAE-FCM was superior to the other clustering models (BIRCH + k-means++, FCM, and SSAE + FCM). In conclusion, the proposed intelligent method for TBM surrounding rock classification is reasonable and applicable for the evaluation of rock mass quality, as well as accurate and sensitive in real-time perception.

Experimental Study on the Influence of Working Parameters of Centrifugal Fan on Airflow Field in Cleaning Room

The air distribution and speed uniformity of the cleaning fan in the cleaning room have a great influence on the working quality of the cleaning system of the harvester. In view of the problem of uneven air distribution in the cleaning room caused by improper adjustment of the main operating parameters of the cleaning fan in the cleaning device of the corn combine harvester, this paper takes the self-developed air screen cleaning test bench as the object. The main working parameters of the cleaning centrifugal fan (air supply distance, fan speed, and number of blades) were simulated and the Fluent simulation software was used to carry out the single-factor and multi-factor optimization tests, explore the influence law of each test factor on the air velocity in front of the screen, in the middle and behind the screen and the deviation degree of the airflow at the back of the screen surface, and find the optimal parameter combination. The data were systematically analyzed by multiple regression method and variance analysis method. The regression model of air velocity at the front, middle, and back of the screen and the air deviation degree at the back of the screen surface for the three working parameters of the cleaning fan were established. The optimal working parameter combination was obtained, that is, when the air supply distance is 580 mm, the fan speed is 1000 r/min, and the number of blades is 10, the airflow velocity in front of the screen is 10.8 m/s, the airflow velocity in the middle of the screen surface is 11.8 m/s, the airflow velocity at the back of the screen surface is 11.2 m/s, and the airflow deviation degree at the back of the screen surface is 13.5%. The relative errors were 1.9%, 0, 2.8%, and 3.0%, respectively. A combined test of the fan and the cleaning screen body with a feeding capacity of 8 kg/s was carried out, and the loss rate was 1.15% and the impurities rate was 1.24%. The regression model was reliable, and the optimal operation parameter combination performed well, meeting the technical requirements of cleaning operation, and providing theoretical guidance for the adjustment of fan structure and operation parameters in the cleaning system of the grain harvester.

Investigation of the Main Parameters Influencing the Kinetics of an Ammonia Stripping Plant Treating Swine Digestate

Ammonia stripping is a consolidated technology that can be adopted to reduce the excessive content of nitrogen in the digestate, thus allowing its reuse as fertilizer within the maximum nitrogen loads set by regulations. In this work, the role of the main operational parameters (airflow and temperature) was assessed on a pilot bubble reactor treating a swine-based digestate, under batch conditions. A kinetic model was developed to correlate temperature, airflow and the ammonia removal yield. Varying the temperature from 60 to 70 °C and the airflow rate from 30 to 60 m3air h−1 m−3digestate, the performance of the plant was measured at different reaction times. The process was favored by the spontaneous pH increase over 10, without basifying agent addition. The lowest removal efficiency (50%) was recorded at 60 °C and 30 m3air h−1 m−3digestate. A removal efficiency higher than 80% was reached running the process at 70 °C and 45 or 60 m3air h−1 m−3digestate. Performance curves were than developed as a practical tool to identify the operating conditions leading to a desired nitrogen removal rate: for instance, under the most severe conditions, up to 80% ammoniacal nitrogen could be removed in about 10 h. Though the obtained results are valid for the treated digestate, the experimental methodology as well as the mathematical model could be replicated in other case studies, thus allowing the amelioration of the process operation.

Multichannel Generator Time-To-Pulse Converter of the Telemetry Temperature Measurement System

The article considers the multichannel time-to-pulse intermediate converter as a part of telemetric temperature measurement system. The principle of operation is based on the use of aperiodic transient in a first-order circuit formed by resistance temperature device and capacitor. Switching of resistance temperature device in the process of temperature measurements is carried out by MIS keys (metal-insulator-semiconductor) according to the signal from the output of the circuit, and the allocation of the output information interval is carried out by a voltage comparator. The article illustrates an electric circuit of a time-to-pulse converter. Based on the equivalent scheme, the main metrological characteristics were obtained by calculation, namely, the dependences of the sensitivity of the output value of the converter to changes in the parameters of the circuit elements expressed in terms of temperature. The scheme of a time-to-pulse converter with an optical output, designed for use with semiconductor resistance temperature devices was experimentally investigated. Variants of multichannel converters for 7 and 15 measuring channels are implemented. Digital elements of the MIS-type (metal-insulator-semiconductor) are used. Information about the temperature at the output of the converters was encoded in the duration of 128 periods of pulse signals, which ensured reliable of information intervals in the receiving part of the equipment. A laboratory tester with an optoelectronic input was used as a receiver of optical pulses. The duration of the information intervals was measured by an industrial measuring device with a resolution of 10 billiseconds. The experimental and rated characteristics of the conversion and the dependence of the conversion error on the supply voltage, operating temperature and resistance of primary thermal converters are presented. It is established that in terms of the main operational parameters, a generator-type time-to-pulse converter is not inferior to a circuit with external excitation. At the same time, the generator converter is less sensitive to the errors of the comparator in terms of electrical bias and speed. The use of a multichannel generator time-to-pulse converter is advisable in telemetric temperature measurement systems when transmitting information in a communication channel during the duration of the period of information, in particular, optical pulses.