Pub Date : 1900-01-01DOI: 10.7551/mitpress/10961.003.0005
A. Rasmuson
AGA AB ndustrial operators worldwide expend considerable time and money to control the release of volatile organic compounds (VOCs) to the atmosphere. Such emissions react with nitrogen oxides to form photochemical oxidants in I the troposphere. Resulting ground-level ozone or smog causes irreparable damage to crops and has been implicated in forest decline. Certain VOCs, particularly chlorinated compounds, are toxic to human health, and many VOCs are malodorous. VOC emissions from a process are controlled in two fundamental ways: Operating conditions are changed to minimize the use of organic compounds. And, control equipment is installed to to capture or destroy VOCs from the exhaust stream. Process changes may involve switching to less harmful solvents, revising operating and maintenance practices, or installing upgraded versions of process equipment. Such modifications can drastically reduce VOC level. However, today's strict regulatory thresholds often call for the installation of end-ofpipe controls. The most common VOGcontrol methods are adsorption, a b sorption, condensation and incineration. To choose the most applicable method for a particular application, the following parameters must be considered: Nature, number and concentration of VOCs in the effluent Exhaust stream flowrate and temperature Viability or desirability of VOC recovery Capital and operating costs Reliability of equipment Required operating time It is not within the scope of this article to present detailed economic comparisons of the competing VOC-control techiques mentioned above. But the results from a recent study comparing adsorption, absorption and condensation are presented in Table 1. Condensation is a well-known VOC-control technique, which is most often used for exhaust streams with relatively low flowrates or high vapor concentrations. To capture organics with relatively low volatility (such as toluene), conventional condensation systems typically use cooling water or refrigeration to attain temperatures to -40°C. However, since most VOCs need substantitally lower condensing temperatures, enhanced condensation is often required. Such systems typically rely on cryogenic coolants, or cascaded, refrigeration units based on chlorofluorocarbon chilling agents. For years, cryogenic condensation with liquid nitrogen has been overlooked due to it5 perceived high operating costs. However, in certain cases, cryogenic condensation is competitive, both technically and economically, thanks in part to its relatively simple and straightloorward operation, which requires very little operator attention. Since the entire exhaust stream must be cooled to condense the offending vapors, the operating costs for a cryogenic condensation system may be prohibitive beyond a certain flowrate, or below a certain VOC concentration. As a general rule of thumb, cryogenic condensation is best suited for flowrates below rough1 1,000 Nm3/h, or vapor concentrations above about 40
AGA AB全球的工业运营商花费了大量的时间和金钱来控制挥发性有机化合物(VOCs)向大气的释放。这些排放物与氮氧化物发生反应，在对流层中形成光化学氧化剂。由此产生的地面臭氧或烟雾对农作物造成无法弥补的损害，并与森林退化有关。某些挥发性有机化合物，特别是氯化化合物，对人体健康有毒，而且许多挥发性有机化合物有臭味。工艺过程中挥发性有机化合物的排放有两种基本控制方法:改变操作条件以尽量减少有机化合物的使用。此外，还安装了控制设备来捕获或破坏废气中的挥发性有机化合物。工艺变更可能涉及改用危害较小的溶剂，修改操作和维护规范，或安装升级版本的工艺设备。这样的修改可以大大降低VOC水平。然而，如今严格的监管门槛往往要求安装管端控制装置。最常见的烟气控制方法有吸附法、吸附法、冷凝法和焚烧法。要选择最适用于特定应用的方法，必须考虑以下参数:排放物中挥发性有机化合物的性质、数量和浓度排气流流量和温度挥发性有机化合物回收的可行性或理想性资本和运行成本设备的可靠性所需的运行时间本文不包括对上述竞争性挥发性有机化合物控制技术进行详细的经济比较。但最近一项比较吸附、吸收和冷凝的研究结果如表1所示。冷凝是一种众所周知的voc控制技术，最常用于相对低流量或高蒸汽浓度的排气流。为了捕获挥发性相对较低的有机物(如甲苯)，传统的冷凝系统通常使用冷却水或制冷来达到-40°C的温度。然而，由于大多数挥发性有机化合物需要较低的冷凝温度，因此通常需要提高冷凝温度。这种系统通常依赖于低温冷却剂，或基于氯氟烃冷却剂的级联制冷装置。多年来，液氮低温冷凝由于运营成本高而被忽视。然而，在某些情况下，低温冷凝在技术和经济上都是有竞争力的，部分原因是其相对简单和直接的操作，几乎不需要操作员的注意。由于必须冷却整个排气流以冷凝有害蒸汽，因此低温冷凝系统的运行成本可能会超过一定的流量或低于一定的VOC浓度。作为一般的经验法则，低温冷凝最适合于流量低于约11,000 Nm3/h，或蒸汽浓度高于约40
{"title":"Capture","authors":"A. Rasmuson","doi":"10.7551/mitpress/10961.003.0005","DOIUrl":"https://doi.org/10.7551/mitpress/10961.003.0005","url":null,"abstract":"AGA AB ndustrial operators worldwide expend considerable time and money to control the release of volatile organic compounds (VOCs) to the atmosphere. Such emissions react with nitrogen oxides to form photochemical oxidants in I the troposphere. Resulting ground-level ozone or smog causes irreparable damage to crops and has been implicated in forest decline. Certain VOCs, particularly chlorinated compounds, are toxic to human health, and many VOCs are malodorous. VOC emissions from a process are controlled in two fundamental ways: Operating conditions are changed to minimize the use of organic compounds. And, control equipment is installed to to capture or destroy VOCs from the exhaust stream. Process changes may involve switching to less harmful solvents, revising operating and maintenance practices, or installing upgraded versions of process equipment. Such modifications can drastically reduce VOC level. However, today's strict regulatory thresholds often call for the installation of end-ofpipe controls. The most common VOGcontrol methods are adsorption, a b sorption, condensation and incineration. To choose the most applicable method for a particular application, the following parameters must be considered: Nature, number and concentration of VOCs in the effluent Exhaust stream flowrate and temperature Viability or desirability of VOC recovery Capital and operating costs Reliability of equipment Required operating time It is not within the scope of this article to present detailed economic comparisons of the competing VOC-control techiques mentioned above. But the results from a recent study comparing adsorption, absorption and condensation are presented in Table 1. Condensation is a well-known VOC-control technique, which is most often used for exhaust streams with relatively low flowrates or high vapor concentrations. To capture organics with relatively low volatility (such as toluene), conventional condensation systems typically use cooling water or refrigeration to attain temperatures to -40°C. However, since most VOCs need substantitally lower condensing temperatures, enhanced condensation is often required. Such systems typically rely on cryogenic coolants, or cascaded, refrigeration units based on chlorofluorocarbon chilling agents. For years, cryogenic condensation with liquid nitrogen has been overlooked due to it5 perceived high operating costs. However, in certain cases, cryogenic condensation is competitive, both technically and economically, thanks in part to its relatively simple and straightloorward operation, which requires very little operator attention. Since the entire exhaust stream must be cooled to condense the offending vapors, the operating costs for a cryogenic condensation system may be prohibitive beyond a certain flowrate, or below a certain VOC concentration. As a general rule of thumb, cryogenic condensation is best suited for flowrates below rough1 1,000 Nm3/h, or vapor concentrations above about 40","PeriodicalId":405668,"journal":{"name":"The Alchemy of Us","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117075239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.7551/mitpress/10961.003.0007
E. Dubinina
Among the many compelling reasons and motivations to make scholarship more open and more accessible to more people, two in particular are gaining ground across the academy: 1) sharing research findings faster through disciplinebased preprint services, and 2) elevating contextual research objects such as code, software, and data to first-class research objects worthy of independent review and recognition. SHARE—a partnership between the Association of Research Libraries (ARL) and the Center for Open Science (COS) to maximize research impact by making research widely accessible, discoverable, and reusable—is already supporting, or is poised to support, these developments in scholarly output. SHARE is a technology platform that aggregates free, open metadata about scholarship across the research life cycle (including proposals, registrations, data, publications, and more) from more than 125 sources, and is steadily adding more metadata providers. SHARE is disciplineagnostic in schema and in type of metadata source. With an application programming interface (API) and open metadata, SHARE can power or feed discovery services for new and emerging forms of scholarly expression in support of their exposure, recognition, and reuse. One such example is a new preprint repository network hosted by COS. As more scholars embrace digital tools and complete their research openly and transparently, disparate digital repositories and platforms are proliferating. By networking these platforms at the metadata level for discovery, SHARE is also becoming a community asset, through which metadata are shared and improved at scale, with a combination of automated intervention and expert human intervention. Although SHARE is co-led by ARL, a membership organization, any organization or repository can participate in providing and consuming data from SHARE. Expanding the impact, openness, and accessibility of scholarship is SHARE’s mission and endgame. Funding agencies and national governments are increasingly requiring openness in recognition of the scientific advances made possible through collaboration, the resource efficiencies of disclosing results and data on a faster basis, and the economic contributions of private sector innovation using open data. From the perspective of scholars of any discipline, sharing workflow components openly means finding collaborators early in the research process. Finding and reusing a tool, algorithm, or piece of code from another project can be time-saving, enabling researchers to concentrate their efforts on their own unique contributions and domain expertise.
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