高压沿面放电烟气脱硫技术动态实验研究

本文针对高压沿面放电活化气体的烟气脱硫技术,在静态实验研究的基础上进行了实验室冷态动态的实验研究。设计了便于反应和测量的动态实验装置。实验解释了电子束法脱硫技术中导致氨气泄漏的部分原因,验证了高压沿面放电脱硫技术可以在较低的运行电压下,达到提高脱硫效率,减少氨气泄漏的作用。     

Physico-Chemistry of the Limestone Sulphation Process

Aspects of the mechanism of the overall reaction between CaCO₃/CaO and SO₂/SO₃ under oxidizing conditions are discussed. The limestone and lime sulphation processes were carried out in a thermobalance under conditions relevant to atmospheric fluidized bed combustion. Sulphated samples, prepared in the form of cross-section particles, were examined in a scanning electron microscope by energy-dispersive X-ray and back-scattered electron imaging. Photomicrographs are presented. The reaction proceeded from the outer surface of the particles and along the pores. Surface textural changes during the reaction were considered. The layer of products was identified as controlling both the rate and extent of limestone/lime sulphation. In the products, two sulphur-bearing solids (CaSO₄ and CaS) were identified. The presence of CaS, which may cause difficulties in practice, is attributed to CaSO₃ disproportionation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Removal of single and dual ring thiophene’s from dodecane using cavitation based processes

Utilising cavitation for enhancing oxidative desulphurization has been investigated for nearly-two decades with recent investigations shifting focus from low-capacity acoustic cavitation (AC) to scalable hydrodynamic cavitation (HC). This work focuses on developing a viable means for removing thiophene’s from fuels. In the first phase of this work, use of vortex based HC devices for removal of single and dual ring thiophenes from dodecane was investigated. HC was shown to be able to remove single ring thiophene from dodecane without using any external catalyst or additives. However, in absence of catalyst or additives, it was not possible to remove dual ring thiophenes such as dibenzothiophene using HC. Therefore, in the second phase of this work, various strategies based on use of catalyst or additives to augment cavitation based process were investigated. AC based experiments were opted for shortlisting suitable catalysts and additives for intensifying cavitation based processes. The influence of using oxidant (H₂O₂) and carboxylic acid catalysts on efficacy of removal of dual ring thiophenes is presented. Several conditions were tested, and the optimal volumetric ratios of 0.95 v/v % H₂O₂ and 6.25 v/v % HCOOH was identified and utilised throughout the remainder of the study. Regeneration of extractant which accumulates oxidised sulphur species from dodecane was also investigated using AC. The additives and process conditions reported in this work are useful for enhancing desulphurization performance.     

Sulphur removal of iron ore tailings by flotation

Iron ore tailings have become one kind of the most hazardous solid waste. Beneficiation of iron ore tailings is a significant issue in the world steel industries, from the point of view of both pollution control and secondary resources. This investigation addressed the processing of tailings with high sulphur content from an iron ore concentrator to produce pellet feed fines and to prevent acid mine drainage. This study was the lab-scale testing of an integrated method consisting of froth flotation combined with gravity and magnetic separation. Reverse flotation located at the end of the primary treatment circuit (high- and low-intensity magnetic separation) will lower a large amount of the sulphur from magnetic separator concentrate. The effects of various operating parameters such as concentrations of collector, frother, depressant and activator, pH, solid-in-pulp concentration have been studied on the sulphur removal using reverse flotation. According to the data presented in this study, the maximum recovery of total sulphur was obtained when the operational parameters were set to the PAX dosage160?gr/t, MIBC dosage 140?gr/t, CuSo₄ 100?gr/t, air flow rate 10?l/min, pH 8.5, and pulp density 30%. With these optimum parameters, final concentrate with the grade of 63.7% Fe and 0.085% S was obtained. The results of this study indicated that, with this method, a great amount of iron concentrate is produced and, simultaneously, the sulphidic fraction is separated that can later be managed more easily owing to the reduced volume.     

纳米碳酸钙微观特征及其促进燃煤脱硫特性研究

为了研究纳米碳酸钙和纳米添加剂在促进燃煤脱硫中的特性,在ZCS-1智能测硫仪中进行纳米碳酸钙脱硫实验研究。结果表明,在炉温900℃、钙硫比为2的条件下,脱硫效率高达90%;1 150℃时达到50%以上。三种纳米碳酸钙的脱硫效果明显好于普通碳酸钙。研究还表明,粒径越小,脱硫效果越好;不同煤种对脱硫效率有较大影响,主要和煤中硫分的含量和硫的分布形态有关;温度是决定脱硫效果的主要因素,900℃下效果最好,超过1 100℃后效果明显下降。SEM和BET分析结果表明,纳米碳酸钙促进脱硫主要是由于其较为丰富的孔隙结构。添加纳米Al2O3和纳米ZnO都能在一定程度上促进纳米碳酸钙脱硫。其中,纳米Al2O3的效果较好,1 150℃能使脱硫效率提高20%左右,达到62%以上。     

排烟增湿脱硫活化反应器内液滴──脱硫剂颗粒碰撞的数值模拟

排烟增湿脱硫活化反应器内液滴──脱硫剂颗粒碰撞的数值模拟唐庆，徐旭常（清华大学热能工程系北京１０００８４）关键词液滴－颗粒碰撞，脱硫，数值模拟要有效的控制ＳＯＺ的污染，降低燃煤电厂排烟中ＳＯＺ的浓度显得尤为重要。在众多的烟气脱硫技术中，排烟增湿活化脱...     

可溶性离子对煅烧烟气脱硫石膏水化的影响

本文主要研究了不同水溶性离子对煅烧烟气脱硫石膏水化过程，也就是对大块煅烧石膏向石膏转化的相变过程的影响. 研究表明，在煅烧石膏向石膏转化的相变过程中，所有的阳离子都能加速煅烧石膏的水化作用，其中Ca²⁺的加速效应最弱. 对于最终沉淀得到的晶体，除了钠离子外，晶体尺寸不受不同种类盐的影响. 而在钠离子中，可以观察到长度大于130 μm的巨型结晶. 本研究阐明了不同离子对煅烧石膏水化的影响，为原始的烟气脱硫石膏在实际应用前的预处理提供了充分的指导.     

One-pot three-component tandem reaction: Synthesis of aryl/alkyl cyanamides libraries and their further conversion into tetrazole derivatives

We have developed methodology for the synthesis of aryl/alkyl cyanamides from amines in one-pot four steps reaction using cheap, readily available and air stable copper source as catalyst under mild reaction conditions. We have also studied the application of cyanamides. In this connection, we could construct aryl tetrazolamine from cyanamides using click reaction     

Studies on polyethylene glycol/polyethersulfone composite membranes for FCC gasoline desulphurization by pervaporation

A polyethylene glycol (PEG)/polyethersulfone (PES) composite membrane that can be applied on a commercial (or scale up) plant for fluid catalytic cracking (FCC) gasoline desulphurization was prepared through pre-wetting combined with double-layer coating methodology. Preparation methodology, morphologies characterization and performance test for the composite membranes were conducted. The results indicated that the pre-wetting method effectively confined the intrusion of PEG solution to porous PES support layer in coating process. The composite membrane had a clear-cut boundary surface between the dense active layer and the porous support layer, which was examined by scanning electron microscope (SEM). Pervaporation (PV) experiments indicated that the membrane, with the crosslinking agent amount of 17% and solids content in active layer solution of 16%, had a stable performance for FCC desulphurization. The sulphur enrichment factor came to 3.63, and the total permeation flux was 3.37 kg/m² h. It was found that the PV performance of the composite membrane changed slightly when the thickness of active layer varied from 4.25 μm to 33.26 μm.