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• LT-MED desalination system is integrated to improve nuclear power plant flexibility. • Peak shaving depth of AP1000 by the integration of desalination system is obtained. • The optimal capacity of LT-MED integrated within AP1000 nuclear unit is obtained. • Thermo-economic performances of the proposed system are evaluated and compared. To accommodate the high penetration of renewable power, nuclear power plants (NPPs) should participate in peak shaving services, which has become a key issue restricting the efficient and reliable operation of NPPs. To enhance the operational flexibility efficiently, the seawater desalination system is integrated within a NPP in this paper. Thermo-economic performances of the proposed system were evaluated. When the main steam, inlet reheat steam, and outlet reheat steam of the NPP are extracted to drive the LT-MED desalination system, and the output power ratios of the integrated system can be decreased to 12%, 65%, and 61%. Therefore, the operational flexibility of the NPP can be effectively enhanced with the integration of desalination system. Then, the capacity and configuration of the LT-MED system were optimized, and gain output ratio and water production cost were used to evaluate performances of the integrated system. The water production cost reaches its minimum value of 0.64 $/m3, when the LT-MED desalination system decreases the output power ratio of the integrated system to 65%. The exergy efficiency of the integrated system is 7.9%, 18.3%, and 25.6% higher than that of AP1000 when the extraction steam is main steam, outlet reheat steam, and inlet reheat steam. [ABSTRACT FROM AUTHOR]

In order to satisfy the requirements of high-quality and high-performance optimal material manufacturing process, it is essential to control the gas system of the manufacturing process. In the actual industry, the quality of products is improved by controlling various gases in the manufacturing process. The tunable laser absorption spectroscopy (TDLAS) technique can be measured by the temperature and concentration of target gas simultaneously. Among the more advanced technologies, CT-TDLAS is the most crucial technique for measuring temperature and concentration distributions across two-dimensional planes. This study suggests a three-dimensional useful measurement of irregular flow or exhaust gases. Furthermore, an optical measurement method has been adopted to measure temperature distribution at a cross-section of the Methane Air premixed turbulent flame. The equivalence ratio of fuel can control this system. The burner system consists of two sections (main flame, sub-flame) for a turbulent flame. In the CT-TDLAS technique, it is essential to set the wavelength for target gases. There is a limit to high-temperature measurement in temperature estimation using a single laser-specific wavelength. Therefore, compared measurement performance was made using a mixed type laser (1388 nm, 1343 nm) and a single type laser (1388 nm). The temperatures obtained by using the optical measurement results were relatively evaluated with those obtained by the thermocouples. It was confirmed that the relative error of the temperature occurred at the central position of the burner. It was about 13.33% by the mixed laser system and 38.33% by the single laser system in most close to point from the burner. [ABSTRACT FROM AUTHOR]

The effect of bipolar pulse mode current ratio (anodic to cathodic) on plasma emission behavior was investigated in Plasma Electrolytic Oxidation (PEO) on AZ91D Mg-Alloy. Two cases of current ratio as 1.20 and 0.88 were applied to the sample. Plasma emission behavior was studied using plasma images and plasma emission measured by photodetector and Intensified Charged-Couple Device (ICCD) camera. The current ratio of greater than 1 shows the continuous increase and then stabilization in emission intensity with a gradual increase in voltage throughout the PEO process. In contrast, the current ratio of less than 1, a sudden drop in plasma emission intensity with voltage was found after 786 s. Therefore, PEO process can be divided into two regimes, arc regime and soft regime, before and after voltage drop, respectively. Results of measured spectra show that a soft regime does not have atomic or ionic excitation during PEO process. It is demonstrated that the growth of porous layer during PEO can be controlled, which is benefit for the protective oxide coating of sample. [ABSTRACT FROM AUTHOR]

To use supplying gases and energy resources efficiently, accurate measurement of irregular gas is necessary. The TDLAS (Tunable laser absorption spectroscopy) technique can be used to control and monitor the supplying gas conditions and combustion of industrial processes. Recently, CT-TDLAS (Computed tomography-tunable diode laser absorption spectroscopy) has been developed to measure the temperature and concentration field of gases. In this study, the 2-dimensional temperature distribution of the Propane-Air premixed flame in several mixing conditions of fuel has been measured by the constructed CT-TDLAS system. 2-Dimensional temperature distributions are measured by 16 path cells. Further, the third-order polynomial regression analysis was applied to resolve the absorption spectra from the incident and transmitted light for a particular gas. The SMART (simultaneous multiplicative algebraic reconstruction technique) algorithm has been adopted for reconstructing the absorption coefficients on the detecting area. As a result of comparing the temperature for the 2-dimensional detecting area using the thermocouple and CT-TDLAS technique, it has been verified that the relative error for the temperatures measured by the thermocouples and calculated by the CT-TDLAS was up to 8%. [ABSTRACT FROM AUTHOR]

Tunable diode laser absorption spectroscopy (TDLAS) technology is a developing method for temperature and species concentration measurements with the features of non-contact, high precision, high sensitivity, etc. The difficulty of two-dimensional (2D) temperature measurement in actual combustors has not yet been solved because of pressure broadening of absorption spectra, optical accessibility, etc. In this study, the combination of computed tomography (CT) and TDLAS with a wide scanning laser at 1335–1375 nm has been applied to a combustor for 2D temperature measurement in high temperature of 300–2000 K and high pressure of 0.1–2.5 MPa condition. An external cavity type laser diode with wide wavelength range scanning at 1335–1375 nm was used to evaluate the broadened H2O absorption spectra due to the high-temperature and high-pressure effect. The spectroscopic database in high temperature of 300–2000 K and high pressure of 0.1–5.0 MPa condition has been revised to improve the accuracy for temperature quantitative analysis. CT reconstruction accuracy was also evaluated in different cases, which presented the consistent temperature distribution between CT reconstruction and assumed distributions. The spatial and temporal distributions of temperature in the high-temperature and high-pressure combustor were measured successfully by CT-TDLAS using the revised spectroscopic database. [ABSTRACT FROM AUTHOR]

Abstract The mass transport and lift enhancement in flows over the NACA0015 airfoil with a synthetic jet (SJ) are studied numerically using Lagrangian coherent structures (LCSs). Trajectories of synthetic particles belonging to 9 different groups in a vicinity of the airfoil are tracked to analyze the transport. The influence of mass transport on the aerodynamic performance of the airfoil and on the surface pressure coefficient distribution is studied. The difference in transport properties for the airfoil with and without the SJ is analyzed to understand the reasons of the lift enhancement. The results show that the LCSs could be successfully used to describe transport and mixing in the complex flows in the blowing and suction phases. More, the fluid originating in the upper reaches is continuously sucked out of the flow field in the suction phase, then the jet injected by the jet slot moves to the lower reaches of the jet slot in the blowing phase. Compared with the original airfoil, the controlled airfoil could bring about the fluid adhering to the surface moving constantly and the lift coefficient improved apparently, whether in the suction or blowing phase. Resulting from the SJ, the high momentum fluid is injected into the flow field near the airfoil. Therefore, the boundary layer separation point of the airfoil is pushed downstream, and the area of the flow separation zone is greatly reduced. Generally, utilizing LCS to study mass transport process can provide a new perspective for the study of the SJ. [ABSTRACT FROM AUTHOR]

Abstract In view of the inevitable influence of variable coal quality for laser-induced breakdown spectroscopy (LIBS) detection, the effects of changes in volatile content on the properties of the laser-induced plasma and spectral signals were investigated using five coal samples, which cover a wide range of volatiles and their coal chars. Results showed that the intensities of most elements in coal were lower than those in coal chars including the major elements (C, H, O and N) and mineral elements (Si, Al, Ca, etc), along with the vaporization and ablation processes of volatile. Volatiles were easily affected by the thermal mechanism due to the high plasma temperature and more volatiles were vaporized in coal samples with higher volatile content. These increase the ionization of volatiles, resulting in the significant decrease of line intensities of mineral elements (Si, Al, Ca existing in ash). There is no significant relationship between the line intensities of major elements (C, H, O and N) and volatile content. Furthermore, the elemental concentration of sample surface areas was measured to reveal the difference between original sample surface, heat-affected area and internal surface of ablated crater to characterize the influence of laser pulse thermal mechanism. The concentration of C in the internal surface of crater and heat-affected area of coal sample was higher than that in the original surface, due to the evaporation of volatiles and other elements caused by thermal mechanism. On the other hand, the concentrations of most mineral elements of the internal surface were lower than that in the original surface. This may be attributed to thermal mechanism, caused by the different rates of volatilization and atomization processes of elements. Graphical abstract Unlabelled Image Highlights • The plasma properties and spectral feature were investigated. • The line intensities changes with vaporization and ablation process of volatile. • The spatially resolved intensities of mineral and major elements was illustrated. • More vaporized volatile matters was pushed to the upper layer of the plasma plume. • The elements concentration of sample surface revealed the effect of thermal mechanism. [ABSTRACT FROM AUTHOR]

The environmental pollution by trace heavy metals is a severe problem for the environment and human health. In this paper, the liquid jet of CsNO 3 solution employed was introduced to the measurement chamber and detected using laser-induced breakdown spectroscopy (LIBS) directly at low pressure to determine the detection features of trace Cs element in liquid. The distinct and round plasma can be acquired when reducing the pressure. The interaction between the plasma core of the liquid jet and the surrounding gas can be controlled to enhance Cs detection ability. Cs emission was mainly in the surrounding area in the plasma. The influences of laser focal point and plasma measurement area on the measured signals were studied under low-pressure condition. When employing the defocus mode and varying the measurement area within a certain range, Cs signal and the signal-to-background ratio were improved. Cs detection limit can reach to 22.8 ppb (3σ/m s ) at pressure of 26 kPa in this paper. According to the discussion, the detection limit will be enhanced when improving the experimental conditions using this method, which shows the great application potential of liquid sample measurement. [ABSTRACT FROM AUTHOR]

The trace carbon (C) composition in ultra-low carbon steel is measured by Laser-Induced Breakdown Spectroscopy (LIBS). Five standard steel samples, with C content between 9 and 89 μg/g, are used to study the performance of LIBS quantitative analysis. Single-pulse LIBS (SP-LIBS) and long-short double-pulse LIBS (LS-DP-LIBS) have been used to measure these five samples. Due to the carbon contamination on sample surface, SP-LIBS cannot obtain an available analysis result. To reduce the influence of carbon contamination, the pretreatment pulse method is employed in this work. The experimental results of the continuous irradiation show that the long-short pretreatment pulses can effectively eliminate the influence of carbon contamination. Finally, the trace carbon in steel samples has been successfully measured by LS-DP-LIBS with pretreatment pulses. The LOD value of carbon is 22.6 μg/g. For the measured five samples, the relative error of prediction (REP%) is between 6.1% and 35.7% and the relative standard deviation (RSD%) is between 13.9% and 58.3%. [Display omitted] • The carbon contamination phenomenon is investigated and discussed for LIBS measurement. • Through the long-short pretreatment pulses, the carbon contamination is effectively reduced. • The trace carbon in steel can be correctly measured by LS-DP-LIBS with the pretreatment pulses. [ABSTRACT FROM AUTHOR]

Sodium-water reaction (SWR) is a design basis accident of a sodium-cooled fast reactor (SFR). A breach of the heat transfer rube in a steam generator results in contact of liquid sodium with water Typical phenomenon is that the pressurized water blows off vaporizes, and mixes with the liquid sodium. It is necessary to quantify the SWR phenomena in the safety evaluation of the SFR system. In this paper a new computer program has been developed and the SWR in a counterfiow diffusion flame is studied by a numerical simulation and an experiment. The experiment is designed based on the numerical simulation so that the stable reaction flame is maintained for a long time and physical and chemical quantities are measured. From the comparison of the analysis and the experiment, there exist discrepancies that may be caused by the assumptions of the chemical reaction.. Hence, a new experiment is proposed to enhance the measurement accuracy and to investigate the reason of the disagreement. The authors propose a depressurized experiment and show the preliminary result of the experiment. It is found that a stable chemical reaction flame is formed. With the depressurization, it is expected that the flame location can be controlled and the reaction region becomes thicker because of decrease in the reactant gas density. [ABSTRACT FROM AUTHOR]

[Display omitted] • A DFG laser system with a wide spectral range was proposed on hydrocarbon measurement. • Fifteen hydrocarbon spectra from C 1 to C 8 were measured. • Concentration dependence of absorbance for each hydrocarbon was evaluated. • Binary to trinary mixtures were analyzed using the ICA and the CLS method. Tunable diode laser absorption spectroscopy (TDLAS) is a widely used diagnostic technique due to its high sensitivity, fast response, low cost, and other merits. Hydrocarbon detection is a field of great interest in the application of tunable diode lasers as hydrocarbons are fundamental molecules in many industrial processes. Many tunable diode lasers are only suitable for single species detection due to the short scanning range and in real situations. However, different hydrocarbon species tend to exist simultaneously. Here we present a laser system based on the difference-frequency generation (DFG) method for simultaneous hydrocarbon mixtures detection. The direct absorption spectra of different hydrocarbons covering various groups (e.g., alkane, olefin, and aromatic) were measured. The measurements of the concentration dependence of absorbance for each molecule were carried out. The R2 values were larger than 0.997, which demonstrated the system can measure hydrocarbons covering different molecular classes accurately. The mixture components were identified using the independent component analysis and quantitative analysis was performed using the classical least-squares method. Future studies will focus on the validation of the system in actual processes. [ABSTRACT FROM AUTHOR]

Collapse of liquid level in reactor pressure vessel (RPV) and uncovery of core in typical pipeline rupture accidents, such as steam generator tube rupture (SGTR), main steam line break (MSLB), and loss of coolant accident (LOCA) for pressurized water reactor (PWR), may occur. This study used APROS to establish a full-scale simulation model of VVER440 reactor and evaluated different break sizes that can lead to RPV liquid level collapse and core uncovery during these accident processes. It is demonstrated that in SGTR accident, the liquid level in RPV collapsed under the condition of four or more heat transfer tube ruptures without the risk of core uncovery in all analyzed cases. In the MSLB accident, RPV liquid level collapse and core uncovery were absent due to the integrity of the primary circuit. In the LOCA accident, the RPV liquid level collapsed under a break size of 0.5% of pipe area (PA) of cold and hot leg. Notably, core uncovery occurred when the break area was 1.8% of PA in the cold leg and 65% of PA in the hot leg. The time required until core uncovery was earlier in the cold leg than that in the hot leg. • Full-scale modeling of the VVER440 pressurized water reactor was conducted using the APROS software. • Critical break sizes that cause core uncovery in pipe rupture accidents is found. • Effect of break sizes on the liquid level of pressure vessel in the pipe rupture accidents is evaluated. [ABSTRACT FROM AUTHOR]

The evolution of vortex structure and mass transport process during dynamic stall of the two-dimensional pitching NACA0012 airfoil are studied in detail, using Lagrangian coherent structures (LCSs), and the nature of dynamic stall is given from viewpoint of nonlinear dynamics. First, the numerical method with SST k − ω turbulence model is used to simulate the flow field around the pitching oscillation airfoil. Then, the Lagrangian-averaged vorticity deviation (LAVD) method is used to analyze the formation and evolution of vortex structure during dynamic stall. Further, the circulation development process of the primary leading edge vortex (LEV) is studied, with comparison between LAVD method with Q criterion. Finally, the dynamic behaviors, such as the mass transport and evolution of flow structure during the process of dynamic stall, are analyzed in depth by using LCSs, and the fluctuation of lift coefficient and the dynamic stall are investigated from the viewpoint of nonlinear dynamics. The results show that the evolution of vortex structure and mass transport are closely related to the fluctuation of lift coefficient during the dynamic stall, and the low-pressure region formed by vortices and the complex mass transport and mixing process on the suction surface of the airfoil are the main reasons for the high lift during the dynamic stall process. In particular, the primary LEV, which can be accurately identified and tracked by LAVD method, plays a very important role in lift enhancement, and the primary LEV and the secondary LEV form and grow in turn by the intermittent feeding process of shear layer. Additionally, the fluid particles in front of the leading edge of the airfoil enter the LEV through a special mass transport channel, which is textured by LCSs and opened and closed intermittently. More importantly, the saddle point of LCSs is an important component of vortex boundary, and its dynamic behaviors represent the behaviors of vortex. The first separation of saddle point from the shear layer at leading edge indicate the separation of primary LEV from the suction surface of the airfoil, and the occurrence of dynamic stall. The second separation of saddle point from the shear layer at leading edge indicate that primary LEV begins to leave the upper region of the airfoil, corresponding to a sharp drop in lift coefficient. Generally, compared to the traditional visualization techniques, the Lagrangian analysis based on LCSs and LAVD can provide a deeper insight into the dynamics of the vortex in flow field around pitching oscillation airfoil and the dynamic mechanism of dynamic stall. [ABSTRACT FROM AUTHOR]

Using Lagrangian Coherent Structures, the influences of synthetic jet parameters, namely, velocity and frequency, on lift at post-stall attack angle are studied in detail, from viewpoint of mass transport. First, the pressure coefficient distribution and the Lagrangian Coherent Structures evolution process of the non-controlled airfoil and the controlled airfoil, at a post-stall attack angle, are compared with each other through numerical simulation, and hence the influences of the mass transport process on the lift coefficient are discussed. Then, the mass transport process and its influences on the lift coefficient under different jet velocities and frequencies are analyzed further. As the conclusion, it can be drawn that there are mainly four routes to enhance the lift of airfoil at post-stall attack angle using synthetic jet, that is, (a) The synthetic jet can directly improve the fluid momentum of the boundary layer in the middle section of the suction surface; (b) The suction phase of the synthetic jet significantly reduces the pressure on the front section of the airfoil suction surface; (c) The synthetic jet could carry the high momentum fluid from the mainstream into the separation zone at the rear section of the airfoil, thus reducing the suction surface pressure of the rear section; (d) The tail vortex reduces the pressure on the suction surface of the airfoil tail. In particular, the jet parameters affect the lift coefficient by these four routes. Specifically, the fluid momenta of the boundary layer in both the front and middle sections of the suction surface are greatly increased with the jet velocity, and the contributions of the tail vortex and the high momentum fluid from the mainstream to the lift are reduced with the jet velocity. As for jet frequency, the contributions of the tail vortex and the high momentum fluid from the mainstream to the lift are reduced with the increase of jet frequency. [ABSTRACT FROM AUTHOR]

The long-short double-pulse laser-induced breakdown spectroscopy (LS-DP-LIBS) method was applied to qualitative and quantitative analyses of underwater steel samples to improve the detection ability of underwater measurement. The stable plasma intensity and discrete emission lines were detected using LS-DP-LIBS when comparing the measured results of single-pulse LIBS (SP-LIBS) and LS-DP-LIBS. The long pulse produces a cavitation bubble without plasma, and the short pulse induces the plasma of steel samples within the bubble. The detection features of LS-DP-LIBS for underwater steel samples were discussed in different intra-pulse delay time, long-pulse width, and delay time conditions when analyzing the measured spectra, the signal intensity of Fe(I) at 400.524 nm and 402.187 nm, Mn(I) at 404.136 nm, and intensity ratio of Mn(I) 404.136 nm/Fe(I) 402.187 nm. The results indicated that the plasma stability and spectral signal intensity were improved significantly with a long-pulse width of 80 µs in the intra-pulse delay time of 70 µs, which were appropriate for bubble formation and plasma generation. According to the discussion of the delay time effect, the state of generated plasma was almost stable from 650 ns to 850 ns. Manganese (Mn) contents in steel samples were analyzed quantitatively when measuring five steel samples with different Mn contents using LS-DP-LIBS in optimal experimental conditions. A strong linear dependence was observed with R 2 =0.9842, which demonstrated the feasibility and appropriateness of quantitative analysis for underwater measurement using LS-DP-LIBS.

Cell-free and concentrated ascites reinfusion therapy (CART) is an effective therapy for refractory ascites. However, CART is difficult to perform as ascites filtration and concentration is a complicated procedure. Moreover, the procedure requires the constant assistance of a clinical engineer or/and the use of an expensive equipment for the multi-purpose blood processing. Therefore, we developed a CART specialized equipment (mobility CART [M-CART]) that could be used safely with various safety measures and automatic functions such as automatic washing of clogged filtration filter and self-regulation of the concentration ratio. Downsizing, lightning of the weight, and automatic processing in M-CART required the use of newly developed multi-ring-type roller pump units. This equipment was approved under Japanese regulations in 2018. In performing 41 sessions of CART (for malignant ascites, 22 sessions; and hepatic ascites, 19 sessions) using this equipment in 17 patients, no serious adverse event occurred. An average of 4494 g of ascites was collected and the total amount of ascites was processed in all the sessions without any trouble. The mean weight of the processed ascites was 560 g and the mean concentration ratio was 8.0. The ascites were processed at a flow rate of 50 mL/min. The mean ascites processing time was 112.5 minutes and a 106.5-minutes (95.2%) ascites processing was performed automatically. The operator responded to alarms or support information 3.2 times on average (3.1 minutes, 2.1% of ascites processing time). Human errors related to ascites processing were detected by M-CART at 0.4 times per session on average and were appropriately addressed by the operator. The frequencies of automatic washing of clogged filtration filter and self-regulation of the concentration ratio were 31.7% and 53.7%, respectively. The mean recovery rates (recovery dose) of protein, albumin, and immunoglobulin G were 72.9%, 72.9%, and 71.2% (65.9 g, 34.9 g, and 13.2 g), respectively. Steroids were administered in 92.7% of the sessions to prevent fever and the mean increase in body temperature was 0.53°C. M-CART is a compact and lightweight automatic CART specialized equipment that can safely and easily process a large quantity of ascites without the constant assistance of an operator., (© 2020 The Authors. Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

A long-short double pulse laser-induced breakdown spectroscopy (long-short DP-LIBS) method was employed to improve the analytical performance of LIBS for the measurement of manganese in steel samples. The long pulse with a duration of 60 μs was generated using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser which was operated at free-running (FR) mode. To investigate the detection ability without sample preparation, the steel washers were tested using single-pulse LIBS (SP-LIBS) and long-short DP-LIBS, respectively. The measurement results show that long-short DP-LIBS was able to record clear spectra from the steel washers with a surface layer. Through the observation on the laser craters with a scanning electron microscope (SEM), the results suggest that the improvement in detection ability can be attributed to the pre-irradiation effect of long-pulse laser beam. Next, the analytical performance for quantitative measurement of manganese was evaluated employing ten standard steel samples. The results show that the linearity fit (R 2 ) of the calibration curve is 0.988 for long-short DP-LIBS, whereas, R 2 is only 0.810 for SP-LIBS under the same measurement conditions. The repeated measurement results show that the average relative standard deviation (RSD) of the tested samples is 29.3% for SP-LIBS and is 10.5% for long-short DP-LIBS. The prediction results also show that the average relative error of prediction (REP) is 94.9% for SP-LIBS and is 4.9% for long-short DP-LIBS.

Collinear long and short dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) was employed to clarify the emission characteristics from laser-induced plasma. The plasma was sustained and became stable by the long pulse-width laser with the pulse width of 60 μs under free running (FR) conditions as an external energy source. Comparing the measurement results of stainless steel in air using single-pulse LIBS (SP-LIBS) and DP-LIBS, the emission intensity was markedly enhanced using DP-LIBS. The temperature of plasma induced by DP-LIBS was maintained at a higher temperature under different gate delay time and short pulse-width laser power conditions compared with those measured using short SP-LIBS. Moreover, the variation rates of plasma temperatures measured using DP-LIBS were also lower. The superior detection ability was verified by the measurement of aluminum sample in water. The spectra were clearly detected using DP-LIBS, whereas it cannot be identified using SP-LIBS of short and long pulse widths. The effects of gate delay time and short pulse-width laser power were also discussed. These results demonstrate the feasibility and enhanced detection ability of the proposed collinear long and short DP-LIBS method.

LI-IT-TOFMS (laser ionization/ion-trap storage/time-of-flight mass spectrometry) is expected to be a powerful tool for environmental monitoring. In the research reported here, real-time LI-IT-TOFMS measurements were carried out on gaseous 2-4 chlorinated PCBs in order to evaluate the applicability of an environmental monitoring method. With respect to ion-trap storage for PCBs, we found that the effect was due to the driving RF voltage on the ring electrode in the ion trap. For PCBs ions produced by laser irradiation, we observed that it was more efficient to reach the center of the ion trap by using a gated RF voltage rather than by using a continuous RF voltage. The ion trajectories in the ion trap were simulated by SIMION 7.0. We found that the voltage of the exit end cap electrode affected both the number of ions trapped and the orbit of ions inside the trap cell. Optimization of this parameter was performed using both simulated and experimental results. The achievable PCBs sensitivity for real-time (1 min) measurement using the LI-IT-TOFMS method was found to be in the pptV range (<0.01 mg/m3N) by means of a comparison with the conventional gas sampling/GS-MS method. A satisfactory proportional relationship was confirmed between the laser-based and conventional results.

Polychlorinated biphenyls (PCBs) are hazardous compounds for which there are few methods involving real-time measurement. Recently, the development of the pulsed-laser technique has enabled us to measure aromatic hydrocarbons quite rapidly. In particular, the LI-TOFMS (laser ionization time of flight mass spectrometry) technique is expected to be a powerful method for on-line, selective and sensitive measurements. In the context of developing a highly selective and sensitive technique, the effective laser wavelength and pulse duration for laser ionization of 2-4 chlorinated PCBs are considered. Excitation at lambda = 266 nm was found to be substantially more effective than at lambda = 280, 300 or 320 nm. Also, picosecond excitation for PCBs underwent more efficient ionization (by a factor of over 10) and less fragmentation than nanosecond excitation. The achievable sensitivity for trichlorinated biphenyl in a real-time (1 min) measurement using the LI-TOFMS technique was estimated to be in the sub-ppbV range (< 0.01 mg/Nm3).

A laser-induced breakdown spectroscopy (LIBS) technique has been applied for detection of unburned carbon in fly ash, and an automated LIBS unit has been developed and applied in a 1000-MW pulverized-coal-fired power plant for real-time measurement, specifically of unburned carbon in fly ash. Good agreement was found between measurement results from the LIBS method and those from the conventional method (Japanese Industrial Standard 8815), with a standard deviation of 0.27%. This result confirms that the measurement of unburned carbon in fly ash by use of LIBS is sufficiently accurate for boiler control. Measurements taken by this apparatus were also integrated into a boiler-control system with the objective of achieving optimal and stable combustion. By control of the rotating speed of a mill rotary separator relative to measured unburned-carbon content, it has been demonstrated that boiler control is possible in an optimized manner by use of the value of the unburned-carbon content of fly ash.