Uncooled Probe Research Articles

Effect of purified dust from CaC2 production and bottom ashes/slags on slagging characteristic of Zhundong coal blend

Coal cofiring with carbon-containing solid wastes can achieve resource utilization and promote the circular economy development. This work aims to investigate the effects of C-rich bottom ashes/slags (BAS), fine/coarse BAS separated by mechanical sieving, and the mixture of untreated BAS with purified dust (PD) from CaC2 production acting as additive on slagging behavior and mineral phase transformation of Zhundong (ZD) coal blend. Detail characterizations including chemical composition, micro-morphology, mineral phases and weight loss of BAS were performed. The ash fusion tests for coal blend with varying proportions of additive were conducted. The compositional analyses of deposits on an un-cooled probe at different sampling temperatures (600/800/1000/1200 ℃) in a drop-tube furnace were investigated. The results show that three types of untreated BAS have similar physicochemical properties. The BAS addition has a negative influence on ash fusion temperatures, but they would completely change the types of crystal minerals in the melted deposits dominated by amorphous substance at 1200 ℃. The addition of 5 wt% coarse (>1 mm) or fine (<53 μm) BAS promotes glassy slags at 1200 ℃ converting into deposits with a low melt fraction, but the influence of fine BAS is more pronounced. A group composed of untreated BAS and PD at an appropriate ratio, promotes the formation of more crystal minerals with high melting points in deposits at 1200 ℃.

Investigation on ash fusion temperature and slagging characteristic of Zhundong coal blends, Part 1: The effect of two solid wastes from calcium carbide production

The potential of purified dust (PD) and removed dust (RD) from calcium carbide production as additive to improve the slagging characteristic of Zhundong (ZD) coal blends was studied. Ash fusion tests with varying proportion of two additives (2.5, 5.0 and 7.5 wt%), and ash sample preparation at 1150/1250 °C were conducted. The deposits at different temperatures (1200/1000/800/600 °C) were collected by using an un-cooled probe which was inserted into a drop-tube furnace. The detail characterizations of ash or slag samples were used for analyzing the transformation of mineral phases, and evaluating the effectiveness of additives. The results show that PD and RD have a feature of Ca and C enrichment. The former has a higher Ca content, while the later owns more abundant C element. The addition of PD or RD improves ash fusion temperatures of coal blends, but the effectiveness of 5.0% PD is the best. The addition of 5.0% PD could convert the glassy slags collected at 1200 °C into deposits with low melting fraction, due to the formation of calcium-rich crystal minerals. Controlling the CaO/SiO2 molar ratio at the range of 2.2– 3 would significantly relieve the high temperature melting behavior of ZD coal blends featured by high Ca and low Si.

Uncooled Microwave Ablation of Osteoid Osteoma: New Approaches to an Old Problem

This study aims to evaluate the technical and clinical success of uncooled microwave ablation (MWA) in the treatment of osteoid osteoma with two-dimensional fluoroscopy guidance in the operating room. The clinical and imaging data of 9 patients were retrospectively evaluated. Mean patient age was 14.55 years. The mean size and volume of the lesions were 17.2 × 10.8 × 8.0 mm and the mean nidus size was 6.86±2.05 mm on computed tomography. MWA was performed with uncooled probe in operating room and in sterile conditions. Numerical pain score was recorded before the procedure, the day after, and at 1, 3 months after the procedure. Clinical and technical success was achieved in 100% of patients. The mean volume of MWA-induced necrosis was 20.8 × 12.8 × 10.7 mm, peripheral scar thickness was 3.5±0.75 mm, and none of the patients had nidus enhancement on first month follow-up magnetic resonance imaging. Fluoroscopic guidance was conducted under digital c-arm. Patients received four to 12 spot films (mean: 6.6 kVp, 2.66 mAs) over the lower extremity. Mean radiation exposure to the skin due to imaging was 0.02 mGy per patient per procedure. The dose area product-the total amount of radiation deliverable to the patient was 0.75±0.32 Gy.cm2. This study demonstrated the effectiveness and the safety of the uncooled MWA in osteoid osteoma. The technique may effectively be used in operating room under c-arm fluoroscopy. Such hybrid approach may ensure sterility, anesthetic safety, and lower radiation dose to patients.

Measurements and CFD modeling of a pulverized coal flame with emphasis on ash deposition

Measurements of fly ash deposition in a 15kW pulverized coal jet flame and CFD-based mathematical modeling have been performed. The deposits have been collected at two ports at particle Stokes numbers in the 0.02–0.34 range and particle kinetic energies not larger than 2×10-9J. Inertial impaction and thermophoresis have been identified as main mechanisms of particle transport towards the deposition surfaces. Deposition rates on air-cooled probes (600–700°C surface temperature) have been measured to be 24% (Port 2) and 79.4% (Port 3) larger than those measured on uncooled probes (1150°C surface temperature) due to the enhanced role of thermophoresis. Complex dependencies of the deposition rate on the probe surface temperature and the probe location have been observed. The CFD-model predictions are able to reproduce these dependencies after adjustments to the particle sticking sub-model. The paper contains estimations of both the impaction and sticking efficiencies.

Investigation of deposit formation and its characterization for a pulverized bituminous coal power plant

Fouling and slagging depend upon the boiler and firing system design, operational parameters and fuel properties. Release of inorganic compounds during combustion and their transformation into critical gaseous species, aerosols and ash particles may substantially affect the boiler efficiency and availability, due to the formation of fireside deposits. The composition of the mineral matter in three bituminous coals and the associated deposits formed at the inlet of the superheater level in a 730MWth pulverized fuel boiler are discussed in this paper. A cooled probe was used to investigate the initial layer of the deposits while an uncooled probe was used to investigate the outer layer. In all initial layers, spherical (formerly molten) iron-rich particles, likely derived from pyrite were observed. Moreover, particles in the initial layers and mineral phases of the coal samples were determined quantitatively. Based on these analyses thermo-chemical equilibrium calculations were performed using the FACT-Sage simulation software to identify the effect of reducing and oxidizing flue gas atmospheres on the ash melting behavior and to assess their importance on the build-up of the initial deposit layers. The results of this work indicate that the deposition of an ash particle is strongly influenced by the particle's history. Besides its composition, in particular, temperature, and the atmosphere that a particle passes through have a significant influence on the mineral transformation and the adhesion of the particle.

Results from combustion of Ekibastuzskii coal and Chelyabinskii brown coal mixture at Troitskaya hydropower plant PK-14-2 boilers

Fouling and slagging depend upon the boiler and firing system design, operational parameters and fuel properties. Release of inorganic compounds during combustion and their transformation into critical gaseous species, aerosols and ash particles may substantially affect the boiler efficiency and availability, due to the formation of fireside deposits. The composition of the mineral matter in three bituminous coals and the associated deposits formed at the inlet of the superheater level in a 730 MWth pulverized fuel boiler are discussed in this paper. A cooled probe was used to investigate the initial layer of the deposits while an uncooled probe was used to investigate the outer layer. In all initial layers, spherical (formerly molten) iron-rich particles, likely derived from pyrite were observed. Moreover, particles in the initial layers and mineral phases of the coal samples were determined quantitatively. Based on these analyses thermo-chemical equilibrium calculations were performed using the FACT-Sage simulation software to identify the effect of reducing and oxidizing flue gas atmospheres on the ash melting behavior and to assess their importance on the build-up of the initial deposit layers. The results of this work indicate that the deposition of an ash particle is strongly influenced by the particle's history. Besides its composition, in particular, temperature, and the atmosphere that a particle passes through have a significant influence on the mineral transformation and the adhesion of the particle.

98/01511 Spray stagnation flames: Li, S. C. Prog. Energy Combust. Sci., 1997, 23, (4), 303–347

Fouling and slagging depend upon the boiler and firing system design, operational parameters and fuel properties. Release of inorganic compounds during combustion and their transformation into critical gaseous species, aerosols and ash particles may substantially affect the boiler efficiency and availability, due to the formation of fireside deposits. The composition of the mineral matter in three bituminous coals and the associated deposits formed at the inlet of the superheater level in a 730 MWth pulverized fuel boiler are discussed in this paper. A cooled probe was used to investigate the initial layer of the deposits while an uncooled probe was used to investigate the outer layer. In all initial layers, spherical (formerly molten) iron-rich particles, likely derived from pyrite were observed. Moreover, particles in the initial layers and mineral phases of the coal samples were determined quantitatively. Based on these analyses thermo-chemical equilibrium calculations were performed using the FACT-Sage simulation software to identify the effect of reducing and oxidizing flue gas atmospheres on the ash melting behavior and to assess their importance on the build-up of the initial deposit layers. The results of this work indicate that the deposition of an ash particle is strongly influenced by the particle's history. Besides its composition, in particular, temperature, and the atmosphere that a particle passes through have a significant influence on the mineral transformation and the adhesion of the particle.

98/01506 Peculiarities of the slow combustion of a hydrocarbon in a ‘wall-less’ reactor with laser heating: Mantashyan, A. A. Combustion and Flame, 1997, 112, (1/2), 261–265

Fouling and slagging depend upon the boiler and firing system design, operational parameters and fuel properties. Release of inorganic compounds during combustion and their transformation into critical gaseous species, aerosols and ash particles may substantially affect the boiler efficiency and availability, due to the formation of fireside deposits. The composition of the mineral matter in three bituminous coals and the associated deposits formed at the inlet of the superheater level in a 730 MWth pulverized fuel boiler are discussed in this paper. A cooled probe was used to investigate the initial layer of the deposits while an uncooled probe was used to investigate the outer layer. In all initial layers, spherical (formerly molten) iron-rich particles, likely derived from pyrite were observed. Moreover, particles in the initial layers and mineral phases of the coal samples were determined quantitatively. Based on these analyses thermo-chemical equilibrium calculations were performed using the FACT-Sage simulation software to identify the effect of reducing and oxidizing flue gas atmospheres on the ash melting behavior and to assess their importance on the build-up of the initial deposit layers. The results of this work indicate that the deposition of an ash particle is strongly influenced by the particle's history. Besides its composition, in particular, temperature, and the atmosphere that a particle passes through have a significant influence on the mineral transformation and the adhesion of the particle.

98/01512 Status and development of combustion technology: Obernberger, I. VDI-Ber., 1997, 1319, 47–79. (in German)

Fouling and slagging depend upon the boiler and firing system design, operational parameters and fuel properties. Release of inorganic compounds during combustion and their transformation into critical gaseous species, aerosols and ash particles may substantially affect the boiler efficiency and availability, due to the formation of fireside deposits. The composition of the mineral matter in three bituminous coals and the associated deposits formed at the inlet of the superheater level in a 730 MWth pulverized fuel boiler are discussed in this paper. A cooled probe was used to investigate the initial layer of the deposits while an uncooled probe was used to investigate the outer layer. In all initial layers, spherical (formerly molten) iron-rich particles, likely derived from pyrite were observed. Moreover, particles in the initial layers and mineral phases of the coal samples were determined quantitatively. Based on these analyses thermo-chemical equilibrium calculations were performed using the FACT-Sage simulation software to identify the effect of reducing and oxidizing flue gas atmospheres on the ash melting behavior and to assess their importance on the build-up of the initial deposit layers. The results of this work indicate that the deposition of an ash particle is strongly influenced by the particle's history. Besides its composition, in particular, temperature, and the atmosphere that a particle passes through have a significant influence on the mineral transformation and the adhesion of the particle.

Chemical Structure of Fuel-Rich 1,2-C2H4Cl2/CH4/O2/Ar Flames: Effects of Micro-Probe Cooling on the Sampling of Flames of Chlorinated Hydrocarbons

Abstract The chemical structure of one-dimensional, fuel-rich, laminar flat flames of 1,2-C2 H4Cl2/CH4/ O2/Ar were studied using a quartz micro-probe and on-line mass spectrometry. Mole fraction profiles determined using the same micro-probe with and without cooling water were considerably different, and indicated the continuation of reactions in the uncooled probe. These results suggest the need to evaluate the effects of probe cooling to acquire quantitative data on the structure of flames of chlorinated hydrocarbons.

The optical and probe measurement of no: A comparative study

Experimental facilities used in comparing the performance of optical and probe sampling methods for measuring NO are described. These measurements were made on flame systems fueled with methane, propane, and Jet-A. Both turbulent and nonturbulent subsonic flows were produced in these systems at temperatures up to 1900 K and a pressure of 1 atm. Optical absorptions by NO in the γ (0, 0) band (∼2265A) were monitored in both high and low resolution. The high resolution (Δλ=0.015A) measurements were made only on flat flames (CH4−O2−N2) using a high pressure Xe lamp. Low resolution (Δλ=1.5 A) measurements were performed with a hollow cathode lamp (NO resonant) on flat flame, swirl burner and jet combustor exhausts. Optical data were reduced using a first principles spectral model and a multiple zone treatment of the opitical path. A comparison of NO measured optically with that measured after sampling with metallic and quartz water-cooled probes indicated agreement to within 25%. Similar agreement was observed only in lean methane flames with an uncooled metallic probe while in rich flames up to 80% of the NO was lost in the uncooled probe. A discussion of the studies done elsewhere which showed large discrepancies (x2–6) between the two techniques, and recent related studies, which did not show large discrepancies, is provided.

Flame Structure Studies. III. Gas Sampling in a Low-Pressure Propane-Air Flame

A previous investigation of this series showed that the temperature in a very lean, low-pressure propaneair flame continues rising for more than a centimeter downstream from the zone of blue luminosity. This suggested a two-stage combustion process: (I) the hydrocarbon oxidizes rapidly and luminously to carbon monoxide; (II) the carbon monoxide oxidizes more slowly to carbon dioxide. The current gas-sampling study has provided support for this hypothesis. Both water-cooled and uncooled probes have been used to obtain gas samples from the region of the flame just beyond the luminous zone. Tests were made to insure that reaction-quenching in the probe was effective and that flame disturbance was minimized. Gas analyses were performed both mass-spectrometrically and by a vacuum-freezing technique. Most of the samples were taken from a flame burning at 46 mm Hg abs pressure, with a mass air-propane ratio of 30. Substantial proportions of CO, and about 15 as much H2, were found as much as a centimeter downstream from the luminous zone, with probes of much less than a millimeter diam. The CO concentration decayed exponentially with distance; a kinetic analysis yielded a decay constant of 231 reciprocal seconds. (The flame temperature was 1605°K.) The H2/CO ratio was considerably less than that corresponding to water-gas equilibrium in the flame. No traces of hydrocarbons were found beyond the luminous zone.