脱硫灰渣的排放方式及利用

火电厂产生的脱硫灰渣的组成和性能与其排放方式有着密切关系。为使其得到较好的处置与利用 ,本文从排放方式方面进行探讨 ,并略述各种脱硫灰渣的性能与利用前景     

THE REACTIVITY AND DURABILITY OF ZINC FERRITE HIGH TEMPERATURE DESULFURIZATION SORBENTS

Cylindrical pellets of zinc ferrite high temperature desulfurization sorbent have been prepared using a number of formulation recipes and induration conditions. Physical and structural properties of the resultant sorbents were measured, and reactivity and durability screening tests were carried out using a single pellet electrobalance reactor. The formulation variables studied were ZnO to Fe₂O₃ ratio, Fe₂O₃ source, and the addition of inorganic (bentonite) and organic (methocel) binders to the sorbents. Pellet induration conditions ranged from 0.25 hours at 815^°C to 4.0 hours at 1038°C. Stronger pellets having greater attrition resistance resulted when 5% bentonite was added to the formulation recipe and when the pellets were indurated at high temperature for extended times. In contrast, bentonite content was not a significant factor in determining sorbent reactivity and durability, both of which were improved by mild induration conditions. Sorbent regeneration temperature was found to be an important factor in improving reaction durability, as was the addition of 0.5% methocel to the formulation recipe. Pellets containing catalyst-grade Fe₂O₃ were more reactive than those containing pigment-grade Fe₂O₃. This effect, however, was less important than the effect of induration conditions.     

Sulfur distribution in coke and sulfur removal during pyrolysis

In order to investigate the mechanisms of coke desulfurization by blowing additional gas into coking chamber during pyrolysis process, some experiments were conducted to study the effects of some factors on the distribution of sulfur in coke. These factors include pyrolysis temperatures, the kinds of the blowing gases and the diameters of coking chamber. It was found that sulfur was mainly released at the range of 300–600 °C. Under this temperature range, the sulfur content in coke can be reduced by 0.05–0.06% by blowing N₂, CO or CH₄, and by 0.14% by blowing H₂ at a space velocity of 1.2 mm/s compared with the absolute sulfur content of 0.92% in the case without gas feeding. Obviously, H₂ is more effective on sulfur removal than N₂, CO or CH₄. The total, organic and inorganic sulfur contents in coke increase with increasing the diameter of coking chamber under identical pyrolysis conditions. Both organic and inorganic sulfur contents in coke increase regularly from the center to brim at identical height of a coke column for all the cases. In addition, the organic and inorganic sulfur contents at the cranny surface are higher than those in interior at the same sampling position. X-ray photoelectron spectroscopy (XPS) analyses suggest that the main contributions to the increase of inorganic and organic sulfur contents are due to the formation of negative bivalent sulfur and thiophenic compounds, respectively.     

Desulfurization of commercial fuels by π-complexation: Monolayer CuCl/γ-Al2O3

Monolayer CuCl/γ-Al₂O₃ sorbent was studied for desulfurization of a commercial jet fuel (364.3 ppmw S) and a commercial diesel (140 ppmw S). The sorbent was prepared by means of spontaneous monolayer dispersion methods. Deep desulfurization (sulfur levels of <1 ppmw) was accomplished with this sorbent using a fixed-bed adsorber. The CuCl/γ-Al₂O₃ sorbent was capable of removing 6.4 and 11.2 mg of sulfur per gram for jet fuel at breakthrough (at <1 ppmw S) and saturation, respectively. The same sorbent was capable of removing 0.94 and 1.8 mg of sulfur per gram for BP diesel at breakthrough and saturation, respectively. The difference in sulfur capacities for jet fuel and diesel was apparently caused by the difference in concentrations of strongly binding compounds, such as nitrogen heterocycles, heavy (polynuclear) aromatics and fuel additives. In comparison with CuCl/γ-Al₂O₃, Cu(I)Y zeolite has higher sulfur capacities but is less stable and can be easily oxidized to Cu(II)Y by fuel additives (such as oxygenates) and moisture and consequently loses π-complexation ability. However, all these cuprous π-complexation sorbents selectively adsorb thiophenic compounds over aromatics and olefins (as predicted by the high separation factors), which resulted in the observed desulfurization capability. A feasibility study is shown for efficient regeneration of CuCl/γ-Al₂O₃ using ultrasound at ambient temperature. Possible problems associated with desulfurization using π-complexation sorbents for commercial fuels are discussed.     

Desulfurization in a plate-type gas-lift photobioreactor using light emitting diodes

Hydrogen sulfide gas was removed in a 2-dimensional gas-lift reactor by the photosynthetic microorganismChlorobium thiosulfatophilum using light emitting diodes (LEDs) as a light source. LEDs saved light energy by 99% compared with the incandescent light source. The plate-type gas-lift reactor removed hydrogen sulfide five times better per unit mg of protein, and performed two times better in the maximum performance per unit luminous flux, compared with cylindrical fermentors.     

国华惠电脱硫及灰渣与主机系统一体化控制研究

本文主要针对神华国华惠州电厂脱硫及灰渣控制系统存在的主要问题,同时结合国家发展改革委和环境保护部提出的＂脱硫脱硝除尘DCS主要参数应逐步设置于同一集控室内＂的具体要求,避免主机集控室与灰硫控制室运行人员在机组异常情况下沟通不及时,造成环保参数超标发生环保事件,给集团公司造成恶劣的影响。重点介绍了在双机不同时停运的情况下,以机组运行安全为第一,逐步实现脱硫及灰渣控制系统单元制改造的过程,同时与主机控制系统联网,达到脱硫及灰渣控制系统与主机控制系统一体化控制的目的,给火力发电厂实现控制系统一体化改造工程一定的借鉴意义。     

Microwave-assisted desulfurization of NOx storage-reduction catalyst

The activity of NO_x storage-reduction (NSR) catalysts is greatly reduced by sulfur poisoning, caused by the SO₂ present in the exhaust stream. Desorption of sulfur species from poisoned NSR catalysts occurs at temperatures in excess of 600 °C using reducing atmospheres and conventional heating. In this work, microwave (MW) heating has been used to promote desulfurization of poisoned NSR catalysts. The experiments were carried out by heating the catalyst with MW radiation and using hydrogen as the reducing gas. Desorption of H₂S at 200 °C was observed. Desorption at even lower temperatures (150 °C) was observed when water was introduced to the system. In the presence of water, sulfur species desorbed as both H₂S and SO₂. An overall reduction of sulfur species of about 60% was obtained. The use of MW heating proves to be an efficient way to achieve regeneration of poisoned NSR catalysts.     

MCM-41-supported Co-Mo catalysts for deep hydrodesulfurization of light cycle oil

Light cycle oil (LCO), a by-product of the fluid catalytic cracking (FCC) process in a petroleum refinery, can be used as a blendstock for the production of diesel and jet fuels. Regulatory and operational issues result in need for new and more active catalysts for the deep hydrodesulfurization (HDS) of diesel feedstocks, such as LCO. This paper reports the activity of a mesoporous molecular sieve MCM-41-supported Co-Mo catalyst in comparison to a commercial γ-alumina (Al₂O₃)-supported Co-Mo catalyst for the desulfurization of a LCO with a sulfur content of 2.19 wt.%. The HDS of dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene—polyaromatic sulfur compounds present in LCO—and their relative reactivities in terms of conversion were examined as a function of time on stream in a fixed-bed flow reactor. The MCM-41-supported catalyst demonstrates consistently higher activity for the HDS of the refractory dibenzothiophenic sulfur compounds, particularly 4,6-dimethyldibenzothiophene. The presence of a large concentration of aromatics in LCO appears to inhibit the HDS of the substituted dibenzothiophenes.     

煤气化过程中单颗粒吸收剂脱硫反应模型概述

对煤气化过程中吸收剂脱硫反应的气固反应模型进行了概述.气固反应模型大致可分为未反应缩核模型,晶粒模型、孔模型及逾渗模型等几种基本型式.未反应缩核模型结构比较简单,可以作为其它模型的基础和组成部分,晶粒模型应用较为广泛且已经得到了充分的发展和改进,孔模型侧重于颗粒内部孔隙特性对反应影响的分析,逾渗模型则基于孔模型将逾渗理论引入来描述脱硫反应过程.     

煤炭复合型助燃固硫剂的开发与研究

通过对不同粒径煤样的全硫量及黄铁矿硫量的测试分析,以及在燃烧过程中生成酸性气体,从而选用复合型碱性固硫剂来进行固硫试验。通过对这几种试验方案的优选比较分析,确定按煤90%∶CaO 9%∶NaCl 1%的配方脱硫率高且成本低廉,可适合工业化生产使用。同时,用高精度微机全自动量热仪做上述配方的煤燃烧热效率实验,结果表明,煤热效率有明显的提高。这说明复合型碱性添加剂不但可促进煤炭的燃烧,同时在燃烧的过程中取到固硫的作用。