Jun Lu

The slopes of fibrations of genus g\geq2 have strict lower (resp., upper) bound, namely \lambda_{m}(g) (resp., \lambda_{M}(g) ). In this paper, we show that if g\neq3 , then each rational number r\in [\lambda_{m}(g),\lambda_{M}(g)] can occur as the slope of some fibration of genus g . A similar result is also true for g=3 and r\in [\lambda_{m}(3),9] .

In this paper, we prove a conjecture of Schnell in the surface case.

The regeneration heat duty (Q_reg, MJ/kg CO₂) which consists of solvent heating energy (Q_sh, MJ/kg CO₂), solvent vaporization energy (Q_vap, MJ/kg CO₂), and desorption energy (Q_des, MJ/kg CO₂), is a critical parameter in evaluating the performance of a solvent for postcombustion CO₂ capture. In this study, Q_reg of CO₂ desorption from rich monoethanolamine (MEA)‐methanol solvent was experimentally evaluated in a pilot‐plant stripper packed with Sulzer packing BX500, Mellapale packing Y500 and Pall rings 16 × 16. And a comparison of Q_reg between MEA‐methanol and aqueous MEA solvent was performed to evaluate the potential for MEA‐methanol's application in industrial CO₂ capture process. Also effects of several operating parameters of the stripper consists of rich CO₂ loading (0.25–0.52 mol/mol), rich solvent flow rate (21.2–51.4 L/h), rich solvent temperature (40–60°C) and regeneration temperature (68–74°C) on the regeneration performance of the stripper were studied. It was found that Q_reg of MEA‐methanol solvent was lower than aqueous MEA solvent (especially Q_des) and Q_reg was sensitive to all the four parameters. Also the results obtained in this work showed that the stripper performance of Sulzer BX500 packing was better than Mellapale Y500 packing and Pall rings 16 × 16 packing was the worst. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 838–844, 2017

The performance of CO₂ absorption into diethylenetriamine (DETA) solvent and CO₂ desorption from rich DETA solvent were experimentally investigated in a lab‐scale CO₂ capture test bed. And the results were compared with monoethanolamine (MEA) solvent, which is a standard solvent for CO₂ capture in industry. Also, effects of solvent concentration, lean CO₂ loading, lean solvent temperature, solvent flow rate and flue gas flow rate on the absorption performance of DETA and MEA solvent, and effects of lean CO₂ loading and solvent flow rate on the regeneration performance of DETA and MEA solvent were studied. The results showed that DETA had a faster CO₂ absorption rate and a higher CO₂ cyclic capacity than MEA solvent. And to strip the same amount of CO₂, DETA needed less regeneration energy than MEA solvent. In addition, the results also showed that key operating parameters of absorber and stripper had large effects on the performance of CO₂ absorption and desorption. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1131–1138, 2017

In this article, the influence of temperature, stirring speed, limestone type, particle size, and desulfurization additives on the limestone dissolution rate was investigated. The dissolution reaction was modeled by shrinking-core model. As the temperature increases, the dissolution reaction rate increased rapidly, and the activation energy was 25.76 kJ/mol. The relation between reaction rate constant and stirring speed was obtained to be k = 0.0205·ω°.⁵¹¹. When the CaCO₃ content of limestone was higher, the improving effect of reducing particle size on dissolution rate will be more significant. Sulfates were found to inhibit the limestone dissolution, while magnesium salts were found to improve the dissolution.

The present study investigated the CO₂ capture characteristics of Structured mesh packing BX500 and Pall ring packing 16 × 16 in the absorption tower by using monoethanolamine-methanol solutions. Moreover, it studied the effects of CO₂ loading, reaction temperatures, liquid flow rate, and gas flow rate on CO₂ capture characteristics. Experimental results concluded that the excellent order of the two fillers was: Structured mesh packing BX500 > Pall ring packing 16 × 16. The absorption temperature at 321 K and the gas flow rate in 1.76 m³/h would be the best choice for CO₂ capture process.

In the study, the optimal experimental conditions for gypsum crystals formation were 323 K, 300 rpm stirring speed. The major impurities of Mg2+, Al3+ and Fe3+ were found to inhibit calcium sulfate crystals formation. Fe3+ caused the strongest inhibition, followed by Mg2+ and Al3+. The influence of desulfurization additives on the gypsum crystals formation was explored with the properties of moisture content, particle size distribution and crystal morphology. The organic desulfurization additives of adipic acid, citric acid, sodium citrate and benzoic acid were investigated. Citric acid and sodium citrate were found to improve the quality of gypsum. Moisture contents were reduced by more than 50%, gypsum particle sizes were respectively enlarged by 9.1 and 22.8%, induction time extended from 4.3 (blank) to 5.3 and 7.8 min, and crystal morphology trended to be thicker.