Pulverized coal combustion application of laser-based temperature sensing system using computed tomography : Tunable diode laser absorption spectroscopy (CT-TDLAS)

The investigation of combustion phenomena in pulverized coal flames is significant for combustion optimization related to energy conservation and emission reduction. Real-time two dimensional (2D) temperature and concentration distributions play an important role for combustion analysis. The non-contact and fast response 2D temperature and concentration distribution measurement method was developed in this study. The method is based on a combination of computed tomography (CT) and tunable diode laser absorption spectroscopy (TDLAS). The accuracy evaluation of developed 32-path CT-TDLAS demonstrated its feasibility of 2D temperature measurement. 32-path CT-TDLAS was applied to CH4 and 5 kg/h coal combustion fields for 2D temperature measurement. The time-series 2D temperature distribution in coal combustion furnace was measured using 32-path CT-TDLAS measurement cell with kHz time resolution. The transient temperature field of combustion flame directly reflects the combustion mode and combustion stability. The measurement results demonstrate its applicability of CT-TDLAS to various types of combustor, especially the combustion fields with coal and ash particles. CT-TDLAS method with kHz response time enables the real-time 2D temperature measurement to be applicable for combustion analysis

Direct measurement of radiation exposure dose to individual organs during diagnostic computed tomography examination

Ionizing radiation from Computed tomography (CT) examinations and the associated health risks are growing concerns. The purpose of this study was to directly measure individual organ doses during routine clinical CT scanning protocols and to evaluate how these measurements vary with scanning conditions. Optically stimulated luminescence (OSL) dosimeters were surgically implanted into individual organs of fresh non-embalmed whole-body cadavers. Whole-body, head, chest, and abdomen CT scans were taken of 6 cadavers by simulating common clinical methods. The dosimeters were extracted and the radiation exposure doses for each organ were calculated. Average values were used for analysis. Measured individual organ doses for whole-body routine CT protocol were less than 20 mGy for all organs. The measured doses of surface/shallow organs were higher than those of deep organs under the same irradiation conditions. At the same tube voltage and tube current, all internal organ doses were significantly higher for whole-body scans compared with abdominal scans. This study could provide valuable information on individual organ doses and their trends under various scanning conditions. These data could be referenced and used when considering CT examination in daily clinical situations

Detailed analysis of distorted retinal and its interaction with surrounding residues in the K intermediate of bacteriorhodopsin

The K intermediate of proton pumping bacteriorhodopsin is the first intermediate generated after isomerization of retinal to the 13-cis form. Although various structures have been reported for the K intermediate until now, these differ from each other, especially in terms of the conformation of the retinal chromophore and its interaction with surrounding residues. We report here an accurate X-ray crystallographic analysis of the K structure. The polyene chain of 13-cis retinal is observed to be S-shaped. The side chain of Lys216, which is covalently bound to retinal via the Schiff-base linkage, interacts with residues, Asp85 and Thr89. In addition, the Nζ-H of the protonated Schiff-base linkage interacts with a residue, Asp212 and a water molecule, W402. Based on quantum chemical calculations for this K structure, we examine the stabilizing factors of distorted conformation of retinal and propose a relaxation manner to the next L intermediate

Detection Improvement of Unburned Carbon Content in Fly Ash Flow Using LIBS with a Two-Stage Cyclone Measurement System

Fly ash contents can be considered as a basis for optimal and stable boiler combustion control and fly ash quality control in power plant, especially the unburned carbon in fly ash. The real-time and quantitative measurement of contents in fly ash was studied using a constructed two-stage cyclone measurement system and detected using laser-induced breakdown spectroscopy(LIBS) technique. The surrounding gas effect, such as CO2 effect on unburned carbon content, was studied comprehensively in this paper. The CO2 effect was eliminated using this proposed combination method of two-stage cyclone measurement system and LIBS with 1ns pulse-width laser according to the efficient gas-particle separation and the controlled laser-induced plasma processes of particle flow. The quantitative analysis was improved using the plasma temperature correction method with the intensity ratio of the emission pair from magnesium as a plasma temperature indicator. The measurement of unburned carbon content in fly ash with temperature correction method presented the concordant results analyzed by chemical analysis method. It is demonstrated the feasibility and improved detection ability for the real-time measurement of fly ash contents in power plant

Improved Measurement Characteristics of Elemental Compositions Using Laser-Induced Breakdown Spectroscopy

Rapid detection of coal and fly ash is significant to improve the efficiency of thermal power plants and reduce environmental pollution. Given its fast response, high sensitivity, real-time, and noncontact features, laser-induced breakdown spectroscopy (LIBS) has a great potential for on-line measurement in these applications. The direct measurement of particles and gases using LIBS was studied, and the method was shown to be effective for this application