Instrument Air Research Articles

Risk assessment and mitigation of airborne disease transmission in orchestral wind instrument performance

In collaboration with 16 musicians from the Minnesota Orchestra, we assess the airflow and particle concentration emitted from ten wind instruments under realistic performance conditions. Anemometer and schlieren measurement techniques are used to quantify the air flow, and aerodynamic particle sizer, laser sheet, and digital inline holography techniques are used to measure the particle concentration. The regions where the flow speed and particle concentrations are above the measurable background level vary among instruments depending on both air flow generation and particle production, but extend no farther than 30 cm from the instrument outlet for all instruments. Farther away, the upward-moving thermal plume generated by the temperature difference between the human body and ambient air is the dominant source of flow and aerosol transport. Brass instrument air flow increases with music amplitude and particle concentration exhibits an inverse response to note duration. Woodwinds emit more particles when note pitch increases. Covering the trumpet bell with one layer of acoustic fabric reduces the emitted particle concentration by ~60% with little impact on the sound quality. Adding more mask layers blocks more particles, but impedes performance and lowers the sound quality at higher frequencies (>1000 Hz). Computational fluid dynamics simulations initialized with experimental data show that placing an air cleaner above the instrument outlet can reduce the particle concentration by 90% due to the thermal plume driving aerosols upwards. Filtration efficiency further increases considerably (~10%) when lowering the ambient temperature from 25 °C to 20 °C to enhance the temperature difference with the human body.

Evaluating the Interoperability of Urban Air Mobility Systems and Airports

This paper investigates how existing arrival and departure procedures can be directly used or adapted to enable high-volume instrument and visual urban air mobility (UAM) flight operations at major airports in the United States. Viable procedures are restricted to those that enable simultaneous and non-interfering UAM flights with conventional aircraft operations. Air traffic controller workload is proposed as the critical integration barrier to scale UAM operations in visual conditions whereas separation minima, especially for approach procedures, is proposed as the critical barrier in instrument conditions. A systems approach is taken to evaluate potential integration strategies for UAM in which the location of UAM runways or vertipads and flight procedures are presented in a topological framework. The benefits, challenges, and notional application of five integration schemes are discussed. Four promising procedures for UAM are introduced through case studies at three airports. Findings indicate that multiple procedures exist to support high-volume UAM integration at major airports under current regulations with additional controller staffing, especially if UAM aircraft exhibit helicopter-like performance.

Surface air pressure–based reconstruction of tropical cyclones affecting Hong Kong since the late nineteenth century

By using instrumental surface air pressure (SAP) records for 1885–2017 at Hong Kong (HK) station, SAP data for 1951–2016 at 66 stations over mainland China and modern tropical cyclones (TCs) of 1951–2017 derived from the Best Tracks (BT) dataset over Northwest Pacific, an objective identification method (OIM) for TCs is developed. Taking HK station as an example, the general distance of detectable landing TCs and the SAP thresholds are determined by utilizing the correlation between the SAP metrics at HK station and those at each landing site for all 392 real modern TC processes during the period of 1951–2016. Then, a long series of TCs affecting HK station for 1885–2017 is reconstructed by applying the thresholds of daily mean SAP and 24-h SAP difference to observed SAP data during the whole stage. The misjudgment of this OIM is about 10%, and it provides a homogeneous series of TCs affecting HK area during 1885–2017. The reconstructed annual TC series shows a visible decreasing trend from 1885 to 2017, with a more obvious reduction occurring after the early 1960s. Specifically, the 10 years of 1994–2003 had the smallest number of TCs. This SAP-based method developed in this study is potentially applicable for other areas.

Optimization of Multilayer Standby Mechanisms in Continuous Processes under Varying Loads

In modern chemical plants, there is a class of continuous processes operated under varying loads. In these processes, the standby mechanisms are needed to ensure that the downstream demand is always satisfied during the operations. Although a few related studies have been reported in literature, a comprehensive analysis of multilayer standby mechanisms in processes under varying loads has not been carried out. In this paper, a generalized mathematical model is developed to automatically generate the optimal standby mechanisms for any given processes by minimizing the total expected lifecycle expenditure. A Matlab code has been developed to perform these optimization tasks via genetic algorithm. The feasibility and effectiveness of the proposed model are demonstrated with the case study concerning a fan system for providing instrument air in a typical chemical plant. From the optimization results, one can determine the optimum configurations of the standby mechanisms, which include: (1) the number of protection layers, (2) the number of both online and spare sensors in the measurement channels, (3) the corresponding voting-gate logic in each channel, (4) the inspection intervals of switch and (5) the number of spares for switch.

Linear Sliding Stem Control Valve Hunting Analysis and Extrapolation of Valve Monitoring Features

Control Valve is one of the major final control elements used in industries and plays a vital role in enhancing the productivity of a plant. Optimization of control valve depends on the effective preventive maintenance schedule. Control valves may be overhauled from the pipeline when there is a suspicion of fault. Almost 80% of the control valve maintenance relates to the diagnosis of valve in service to detect any abnormality. When a fault is identified the preventive maintenance process shifts to the breakdown maintenance process. During this process the control valve components are tested to determine the cause of the problem and to establish a corrective course of action. With the developments in microprocessor based control valve instruments along with their diagnostics capabilities has allowed engineers to simplify the maintenance activities. These digital devices can identify problems related with instrument air quality, leakage, supply pressure restriction, excessive friction, dead band, and calibration shift. Troubleshooting control valves after installing in the field is a tedious process as it is difficult to discriminate whether the problem is in the control valve or in the controller tuning. This article presents a novel method using sensors to identify the problems related with the control valve hunting, to pinpoint the source of error and present the performance results to end user. The objective of this research is to reduce manual intervention in troubleshooting of control valves and to enhance the predictive maintenance resulting in cost effective production.

Volume characterisation of the electrical discharge

In this paper, theoretical and practical study of gliding arc discharges is presented considering the discharge itself. The characteristics of the gliding arc are studied at different flow rate values. For this study case instrumental air was used in order to elongate the spark thus obtaining the gliding arc. The comparison took into consideration linear approximations of the discharge compared to the real phenomena.
 

Measurement of "Reed to Room"-Transfer Functions

A method is proposed here to synthesize the acoustic response of a room to a musical reed wind instrument with tone holes played by a musician. The procedure uses convolution of a) two measured pulse responses and b) the mouthpiece pressure during playing. The novelty of the approach is to include the sound radiation directivity of the source in the impulse response measurement of the room by using the wind instrument's air column as an exciter. At the reed input end of the air column pressure pulses at typical peak pressures of several kilopascals are generated using a compressor and a solenoid valve, which provides a high SNR even at distant measurement positions. For auralization purpose, the source signal measurement is done very close to the sound generation locus, i.e. inside the mouthpiece. Because this measurement is largely insensitive to room acoustics, the proposed method can be considered a very convenient alternative to music recordings in anechoic conditions. As a proof of concept we report here experimental results for the case of a bassoon. The method can be extended to auralizations of reed and lip-reed musical instruments in virtual acoustic scenes, and sheds light on the importance of the reflective and radiative properties of the air column for the sound coloration.

Proactive and Predictive Maintenance Strategies and Application for Instrumentation & Control in Oil & Gas Industry

Instrumentation & Control Systems have gone through various revolutions in the oil and gas industry. The start of the industry was based on pneumatic controllers, operating with instrument air or instrument gas at 0.2 to 1.0 barg and the Instrument Protective System (IPS) was relay based. This system provided almost zero information or data that can be used to predict failure and had a higher unrevealed failure. The next phase of instrumentation was migration into the electronics era. This allowed for the migration from a pneumatic system to the application of electronics field device operation on 4-20mA connected to Distributed Control System (DCS) and IPS. Further development of 4-20mA communication protocol allowed for the development of digital superimpose communication called Highway Addressable Remote Transducer (HART). The data that is transmitted in HART protocol provides sufficient data and information to predict the health and functionality of the instrumentation. Changes in the maintenance philosophy from reactive maintenances to proactive or predictive maintenances, resulted in reduced downtime by scheduling maintenance to optimize the working window. This work process allows for greater productivity of assets, both human and capital. Dashboards are developed and utilised to alert fault detection and loss of redundancy, whereby data is relayed from DCS and IPS to a web-based system. Available tools being developed in the industry and application of IoT within the industry allows for real-time field device health monitoring and an engine to predict deviations. The strength and weakness of the various proactive or predictive maintenance strategies are compared and summarized, including scope for future research and application in the industry.

Implementation of a top-down noise control strategy for a liquefied natural gas peak-shaving facility

ABSTRACTThere have been many previous noise-related studies on liquefied natural gas (LNG) facilities in the United States; however, noise control of these facilities using a top-down approach has not been explored in detail. Most studies have demonstrated noise compliance to applicable standards by focusing on a combination of treatments and specifications, with less consideration on control technology feasibility, ranking, and cost-effectiveness. The Federal Energy Regulatory Commission (FERC) prohibits natural gas facilities from emitting day-night noise levels in excess of 55 dB(A) (equivalent to 24-hr continuous level of 49 dB(A)) at nearby receivers. A case study was conducted to evaluate a top-down approach to reduce noise at a typical LNG peak-shaving facility under normal operating conditions, accounting for technical feasibility, control effectiveness, and cost implications. A modeling approach (International Organization for Standardization standard ISO 9613-2) was used to predict and evaluate the facility’s noise reduction potential. The study found that the strategy could achieve feasible and environmentally effective reductions up to 11 dB(A) at 500 m from the facility by first identifying source groups with highest-emitting sources and then targeting major noise source contributors per group. This approach is cost-effective because the FERC noise goals can still be achieved by avoiding unnecessary control costs associated with lower-ranked sources. The study identified the following four source groups as the highest noise emitters: (1) liquefaction and instrument air, (2) boil-off gas (BOG) compression, (3) glycol water system (air coolers), and (4) pretreatment. Of all the treatments evaluated, installation of enhanced silencers for gas turbine (GT) package—as well as construction of an acoustical building for the BOG compressors and drivers—resulted in the greatest noise reduction at nearby receivers. The study notes that incremental treatment costs presented in this paper are approximate estimates that may vary depending on factors such as facility size and region.Implications: This study assessed potential noise reductions associated with implementing a top–down noise control strategy on a typical LNG peak-shaving facility. The study determined the top–down noise control strategy could achieve feasible and environmentally effective reductions up to 11 decibels at receivers within 500 m from the facility’s center. As LNG suppliers need to support potential supply disruptions, some regions of the US, including New England and Gulf Coast with projected increase in LNG exports and growing needs from power sector, may find information in this study useful with regard to evaluating and prioritizing noise reduction potential of their LNG peak-shaving facilities.

Occupational exposure to gaseous and particulate contaminants originating from additive manufacturing of liquid, powdered, and filament plastic materials and related post-processes

The aim of this study was to measure the concentrations of gaseous and particulate contaminants originated from additive manufacturing operations and post-processes in an occupational setting when plastics were used as feedstock materials. Secondary aims were to evaluate the concentration levels based on proposed exposure limits and target values and to propose means to reduce exposure to contaminants released in additive manufacturing processes. Volatile organic compounds were sampled with Tenax TA adsorption tubes and analyzed with a thermo desorption gas chromatography-mass spectrometry instrument. Carbonyl compounds were sampled with DNPH-Silica cartridges and analyzed with a high-performance liquid chromatography device. Particles were measured with P-Trak instrument and indoor air quality was sampled with IAQ-Calc instrument. Dust mass concentrations were measured simultaneously with a DustTrak DRX instrument and IOM-samplers. Particle concentrations were highest (2070-81 890 #/cm3 mean) during manufacturing with methods where plastics were thermally processed. Total volatile organic compounds concentrations, in contrast, were low (113–317 µg/m3 mean) during manufacturing with such methods, and vat photopolymerization. However, total volatile organic compounds concentrations of material jetting and multi jet fusion methods were higher (1,114–2,496 µg/m3 mean), perhaps because of material and binder spraying, where part of the spray can become aerosolized. Chemical treatment of manufactured objects was found to be a severe volatile organic compounds source as well. Formaldehyde was detected in low concentrations (3–40 µg/m3) in all methods except for material jetting method, in addition to several other carbonyl compounds. Notable dust concentrations (1.4–9.1 mg/m3) were detected only during post-processing of powder bed fusion and multi jet fusion manufactured objects. Indoor air quality parameters were not found to be notably impacted by manufacturing operations. Only low concentrations (below 2 ppm) of CO were detected during several manufacturing processes. All studied additive manufacturing operations emitted potentially harmful contaminants into their environments, which should be considered in occupational additive manufacturing and workplace design. According to the measured contaminant levels it is possible that adverse additive manufacturing related health effects may occur among exposed workers.

Analysis of spatial and temporal patterns of on-road NO<sub>2</sub> concentrations in Hong Kong

Abstract. In this paper we present an investigation of the spatial and temporal variability of street-level concentrations of NO2 in Hong Kong as an example of a densely populated megacity with heavy traffic. For the study we use a combination of open-path remote sensing and in situ measurement techniques that allows us to separate temporal changes and spatial patterns and analyse them separately. Two measurement campaigns have been conducted, one in December 2010 and one in March 2017. Each campaign lasted for a week which allowed us to examine diurnal cycles, weekly patterns as well as spatially resolved long-term changes. We combined a long-path differential optical absorption spectroscopy (DOAS) instrument with a cavity-enhanced DOAS and applied several normalizations to the data sets in order to make the different measurement routes comparable. For the analysis of long-term changes we used the entire unfiltered data set and for the comparison of spatial patterns we filtered out the accumulation of NO2 when stopping at traffic lights for focusing on the changes of NO2 spatial distribution instead of comparing traffic flow patterns. For the generation of composite maps the diurnal cycle has been normalized by scaling the mobile data with coinciding citywide path-averaged measurement results. An overall descending trend from 2010 to 2017 could be observed, consistent with the observations of the Ozone Monitoring Instrument (OMI) and the Environment Protection Department (EPD) air quality monitoring network data. However, long-term difference maps show pronounced spatial structures with some areas, e.g. around subway stations, revealing an increasing trend. We could also show that the weekend effect, which for the most part of Hong Kong shows reduced NO2 concentrations on Sundays and to a lesser degree on Saturdays, is reversed around shopping malls. Our study shows that spatial differences have to be considered when discussing citywide trends and can be used to put local point measurements into perspective. The resulting data set provides a better insight into on-road NO2 characteristics in Hong Kong, which helps to identify heavily polluted areas and represents a useful database for urban planning and the design of pollution control measures.

Process resilience analysis based data-driven maintenance optimization: Application to cooling tower operations

In a process plant system, safe and reliable operations are highly sensitive to utilities such as power, steam, cooling water, nitrogen, and instrument air. These play an important role or act as safety barriers. This is because a disturbance in their supply is likely to affect process operations downstream, may reduce the production efficiency, and may lead to a sudden shutdown or contribute to an unsafe condition. The focus of this paper is to introduce and evaluate a model for survival of a process system under upset conditions using the Process Resilience Analysis Framework (PRAF). Resilience metrics within a data-driven and model-based optimization approach using Bayesian regression are employed integrating both technical (process parameter variations) and social (human and organizational) factors. Based on an optimization objective function accounting for the overall system performance in terms of energy consumption, maintenance costs, safety impact, environmental impact, asset damage, and production loss, the proposed methodology aims to determine the optimal maintenance policy for optimal and safer plant operations. The implementation of the survival model within the PRAF is demonstrated on a cooling tower operation example problem, where optimal operation and maintenance (preventive, corrective, and predictive) strategies are determined based on trade-off analysis of process revenue, safety impact, and maintenance costs.

Beyond HAZOP: Analyzing common cause and system scenarios

A production operation often consists of multiple unit operations, supported by plant‐wide services such as instrument air, power, electronic communications, and cooling water. The production operation can be covered by multiple risk studies, which divide up the production operation based on nontechnical reasons, such as unit management, study length, and convenience. The use of multiple studies is particularly common with large production units or with integrated packaged equipment. The “divide and conquer” approach to the studies is good for planning and execution, but the resulting “pieces and parts” analysis can allow significant common cause scenarios to get lost in the clutter. Traditional HAZOP approaches generally focus on pairing individual causes with deviations and consequences. This traditional approach can result in inadequate consideration of more complex scenarios, such as those involving: Multiple automated system actions Global loss of service Transference of risk These complex scenarios are often interrelated and thus are not well suited for analysis by HAZOP procedures that mandate a single cause‐consequence relationship. This article will propose extensions to the typical HAZOP process to address these challenges in a more holistic manner. © 2018 American Institute of Chemical Engineers Process Saf Prog 38: e11997, 2019

Sensitivity of Ambient Atmospheric Formaldehyde and Ozone to Precursor Species and Source Types Across the United States.

Formaldehyde (HCHO) is an important air pollutant from both an atmospheric chemistry and human health standpoint. This study uses an instrumented photochemical Air Quality Model, CMAQ-DDM, to identify the sensitivity of HCHO concentrations across the United States (U.S.) to major source types and hydrocarbon speciation. In July, biogenic sources of hydrocarbons contribute the most (92% of total hydrocarbon sensitivity), split between isoprene and other alkenes. Among anthropogenic sources, mobile sources of hydrocarbons and nitrogen oxides (NO x) dominate. In January, HCHO is more sensitive to anthropogenic hydrocarbons than biogenic sources, especially mobile sources and residential wood combustion (36% of national hydrocarbon sensitivity). While ozone (O3) is three times more sensitive to NO x than hydrocarbons across most areas of the U.S., HCHO is six times more sensitive to hydrocarbons than NO x, largely due to sensitivity to biogenic precursors and the importance of low-NO x chemistry. In winter, both HCHO and O3 show negative sensitivity to NO x (increases with the removal of NO x), although O3 increases are larger. Relative sensitivities do not change substantially across different regions of the country.

Compressed Air Quality, A Case Study In Paiton Coal Fired Power Plant Unit 1 And 2

The compressed air system becomes part of a very important utility system in a Plant, including the Steam Power Plant. In PLN’S coal fired power plant, Paiton units 1 and 2, there are four Centrifugal air compressor types, which produce compressed air as much as 5.652 cfm and with electric power capacity of 1200 kW. Electricity consumption to operate centrifugal compressor is 7.104.117 kWh per year. Compressed air generation is not only sufficient in quantity (flow rate) but also meets the required air quality standards. compressed air at Steam Power Plant is used for; service air, Instrument air, and for fly Ash. This study aims to measure some important parameters related to air quality, followed by potential disturbance analysis, equipment breakdown or reduction of energy consumption from existing compressed air conditions. These measurements include counting the number of dust particles, moisture content, relative humidity, and also compressed air pressure. From the measurements, the compressed air pressure generated by the compressor is about 8.4 barg and decreased to 7.7 barg at the furthest point, so the pressure drop is 0.63 barg, this number satisfies the needs in the end user. The measurement of the number of particles contained in compressed air, for particle of 0.3 micron reaches 170,752 particles, while for the particle size 0.5 micron reaches 45,245 particles. Measurements of particles conducted at several points of measurement. For some point measurements the number of dust particle exceeds the standard set by ISO 8573.1-2010 and also NACE Code, so it needs to be improved on the air treatment process. To see the amount of moisture content in compressed air, it is done by measuring pressure dew point temperature (PDP). Measurements were made at several points with results ranging from -28.4 to 30.9 °C. The recommendation of improving compressed air quality in steam power plant, Paiton unit 1 and 2 has the potential to extend the life of instrumentation equipment, improve the reliability of equipment, and reduce the amount of energy consumption up to 502,579 kWh per year.

Effects of oxygenate additive mixture on the performance and emission characteristics of a biodiesel fuelled compression ignition engine

An experimental investigation was conducted to discover the effects of oxygenate mixture as additives in Jatropha biodiesel on the performance and emission characteristics of a direct injection compression ignition engine. The experiments were conducted in an instrumented single cylinder air cooled four stroke direct injection diesel engine (running at constant speed of 1500 rpm and injection timing of 26° bTDC), AC alternator and an electric loading device. Four oxygenate additives, namely, Dimethyl carbonate (C3H6O3), Ethylene glycol (C2H6O2), Propylene glycol (C3H8O2) and 2-Butoxyethanol (C6H14O2) were selected, and nine different combinational oxygenate test fuels were prepared attaining ratios of 1, 2 and 4% volume of oxygenates with biodiesel. Reduction in CO by 60%, Unburned HC by 11% and smoke emissions by 27% were observed for the test fuels without conciliating the brake thermal efficiency improvement by 6%, while NO emission increased marginally by 4%.

Experimental aspects of buoyancy correction in measuring reliable high-pressure excess adsorption isotherms using the gravimetric method

Addressing reproducibility issues in adsorption measurements is critical to accelerating the path to discovery of new industrial adsorbents and to understanding adsorption processes. A National Institute of Standards and Technology Reference Material, RM 8852 (ammonium ZSM-5 zeolite), and two gravimetric instruments with asymmetric two-beam balances were used to measure high-pressure adsorption isotherms. This work demonstrates how common approaches to buoyancy correction, a key factor in obtaining the mass change due to surface excess gas uptake from the apparent mass change, can impact the adsorption isotherm data. Three different approaches to buoyancy correction were investigated and applied to the subcritical CO2 and supercritical N2 adsorption isotherms at 293 K. It was observed that measuring a collective volume for all balance components for the buoyancy correction (helium method) introduces an inherent bias in temperature partition when there is a temperature gradient (i.e. analysis temperature is not equal to instrument air bath temperature). We demonstrate that a blank subtraction is effective in mitigating the biases associated with temperature partitioning, instrument calibration, and the determined volumes of the balance components. In general, the manual and subtraction methods allow for better treatment of the temperature gradient during buoyancy correction. From the study, best practices specific to asymmetric two-beam balances and more general recommendations for measuring isotherms far from critical temperatures using gravimetric instruments are offered.

Comments to the paper “Analysis of early instrumental air temperature observations before and after the Tambora volcano eruption”

Comments to the paper “Analysis of early instrumental air temperature observations before and after the Tambora volcano eruption”

Analysis of early instrumental air temperature observations before and after the Tambora volcano eruption

The study analyzes the recently summarized data on surface air temperature in the east of North America, in Western and Eastern Europe, and in India before and after the Tambora volcano eruption occurred in Indonesia in 1815. The well-known fact is proved that no cooling occurred after the Tambora eruption in the east of Europe and in India. It is found that the insignificant (at the decadal timescale) cooling was observed in all analyzed regions: it started earlier than the Tambora eruption and than the stronger eruption of another volcano in 1809. The paper demonstrates that it is impossible to reveal cause-effect relations between the general cooling and the eruption of the above volcanoes based on the available data on surface air temperature. Cold snaps that follow the later volcanic eruptions were identified by meteorologists using the data of the whole network of meteorological observations established in the second half of the 19th century. However, these cold snaps cannot be detected using data on surface air temperature only.

The reply of the authors to the comments by A.A. Kiselev to the paper “Analysis of early instrumental air temperature observations before and after the Tambora volcano eruption”

The reply of the authors to the comments by A.A. Kiselev to the paper “Analysis of early instrumental air temperature observations before and after the Tambora volcano eruption”