Mathematical modelling of sewage sludge incineration in a bubbling fluidised bed with special consideration for thermally-thick fuel particles

Fluidised bed combustor (FBC) is one of the key technologies for sewage sludge incineration. In this paper, a mathematical model is developed for the simulation of a large-scale sewage sludge incineration plant. The model assumes the bed consisting of a fast-gas phase, an emulsion phase and a fuel particle phase with specific consideration for thermally-thick fuel particles. The model further improves over previous works by taking into account throughflow inside the bubbles as well as the floating and random movement of the fuel particles inside the bed. Validation against both previous lab-scale experiments and operational data of a large-scale industrial plant was made. Calculation results indicate that combustion split between the bed and the freeboard can range from 60/40 to 90/10 depending on the fuel particle distribution across the bed height under the specific conditions. The bed performance is heavily affected by the variation in sludge moisture level. The response time to variation in feeding rate is different for different parameters, from 6min for outlet H(2)O, 10min for O(2), to 34min for bed temperature.     

岩豆凝集素的纯化及其分子残基的化学修饰和活性关系

岩豆种子经侵取、硫酸铵分级、ＤＥＡＥ－纤维素离子交换和ＳｅｐｈａｄｅｘＧ－１００分子筛层析，获得ＦＰＬＣ上单一的凝集素样品，对此纯化的凝集素样品用Ｎ－溴代丁二酰亚胺、Ｎ－乙基顺丁烯二酰亚胺、二流苏糖醇，碘乙酸和对氯汞苯甲酸修饰其分子内的色氨酸和巯基．经计算，该凝集素分子内含有４个色氨酸和２４个流基，当色氨酸被修饰后其凝集活性全部丧失，而巯基被修饰后对其凝血活性无任何影响，表明巯基与凝集素分子的凝血活性无关，而色氨酸则是凝集活性所必需的基团．     

浙江嘉善东部区域盛家湾河道缓冲带及水生态修复实践

河流生态修复是改善水质和维持河流生态系统稳定的重要措施,是贯彻落实“十四五”重点流域水生态环境保护总体要求的重要举措。以嘉善姚庄镇俞汇塘支流盛家湾河道为研究对象,探讨了河流缓冲带与水生态修复工程实践。针对该区域生态空间严重被挤占、部分河段生境受损严重、生物多样性降低、河道水质不稳定等环境问题,提出了以保护—修复—发展为创新思路的盛家湾河道生态修复工程总体方案;以全面提升河道的水生态环境质量、构建健康稳定的水生态系统为修复目标,实施了面源污染阻控、生态空间恢复以及水生态修复等工程,其中包括面积为17 700 m²的人工湿地及2 200 m长的生态植草沟建设,约30 m宽和1 480 m长的陆域植被缓冲带构建,1 210 m长的河岸线生态化改造,以及面积为20 400 m²的水下森林生态修复工程。通过盛家湾河道的生态修复,全面改善了盛家湾区域的生态环境,实现了“水清岸绿”,恢复了水体的生物多样性。

     

受限空间环境压力对三元锂离子电池热失控影响

为研究三元锂离子电池在空运低压环境中的安全性,通过自主设计搭建的封闭式变压实验舱开展相关实验,对不同荷电状态(SOC)下的三元锂离子电池在不同压力环境(101,80,60,40 kPa)下的热失控特性进行研究,采集电池热失控过程中的温度以及实验舱内的压力变化,并对热失控后实验舱内的气体成分进行分析.结果表明:三元锂离子...     

化学消毒法与医疗废物处理

本文介绍了医疗废物化学消毒处理技术和标准要求,并对采用该方法处理医疗废物在我国的应用提出了相关建议。     

汶川大地震宏观震中问题的讨论

采用大地震诱发崩塌滑坡特点与地面破坏程度相结合,以及极震区几何中心方法,定性判定了汶川大地震的宏观震中位置。判定结果是汶川大地震应该有2个宏观震中,一是映秀镇牛圈沟为映秀极震区宏观震中,坐标位置:31.045 6°N,103.455 6°E;二是北川老县城为北川极震区宏观震中,坐标位置:31.863 7°N,104.361 0°E。两种判定方法相比,前者更符合山区特殊地质地貌环境下的地震破坏规律。     

Hawaiian Residents’ Preferences for Miconia Control Program Attributes Using Conjoint Choice Experiment and Latent Class Analysis

Invasive species control or eradication is an important issue. On the islands of Hawaii, this problem is exceedingly evident when it comes to Miconia calvescens (Miconia). Adequate funding is needed to control or eradicate this invasive plant, but with the limited amount of funding available for the fight against Miconia, it is important to make sure that the fund is being spent in a way that addresses the needs or preferences of the Hawaiian residents. Using the conjoint choice experiment method, we designed a survey that would measure the Hawaiian residents’ willingness to support Miconia control program attributes. The attributes focused on were cost, biodiversity loss, extent of spread and soil erosion. Latent class approach was used to assess the surveyed population to see the different preferences by individual classes. The results show three different classes or groups of individuals with varying preferences for a control program of which cost and erosion were the top preferred attributes among the classes. These groups were defined by their socio-demographics of income, the length of residency and exposure to farming/gardening activities. Even with a preference for lower cost, a group showed willingness to pay more ($2.40) for a program that reduces erosion from high to low. Finally, the biodiversity attribute had very low consideration from a majority of the respondents showing the need for educating the public regarding its importance in preserving the unique environment in Hawaii.     

Assessment of popular techniques for co-processing municipal solid waste in Chinese cement kilns

• Municipal solid waste (MSW) was fermented, screened, gasified, then co-processed. • Co-processing MSW in cement kilns could cause excessive pollutant emissions. • Bypass flue gas can be disposed of through the main flue system. • Popular MSW co-processing methods do not affect cement quality. Cement kiln co-processing techniques have been developed in the past 20 years in China, and more than 60 factories now use fermentation, screening, and gasification pre-treatment techniques to co-process municipal solid waste (MSW). There three complete MSW pre-treatment techniques, co-processing procedures, and environmental risk assessments have been described in few publications. In this study, we assessed the effectiveness of each technique. The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard. To reveal the mechanisms of pollutant migration and enrichment, the substances in the kiln and kiln products are investigated. The input of co-processing materials (Co-M) produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/Fs) in the bypass flue gas (By-gas) in excess of the regulatory standard. The Co-M input produced by the screening and gasifier technologies caused the total organic carbon (TOC) concentration to exceed the standard. In addition, the NO_x, TOC, and PCDD/Fs in the By-gas exceeded the regulatory standard. Raw meal was the primary chlorine and heavy metals input stream, and clinker (CK) and cement kiln dust (CKD) accounted for>90% of the total chlorine output stream. Flue gas and CKD were the primary volatile heavy metal (Hg) output streams. Greater than 70% of the semi-volatile heavy metals (Cd, Pb, Tl and Se) distributed in hot raw meal and bypass cement kiln dust. The low-volatility heavy metals were concentrated in the CK. These results indicated that co-processing techniques used in China still require improvement.