用示踪气体法评价和优选吸气罩

目的 在粉尘发生源处设置适用的局部吸气罩,可以有效地控制粉尘向周围扩散,是预防尘肺病发生的有效措施。为了提供适宜吸气罩的设计,使用了示踪气体法评价吸气罩的效率,对吸气罩的设计进行优选,以提高捕集效率和降低能耗。方法 建立示踪气体评价吸气罩效率的实验风道和方法,采用人工煤气作为示踪气体。结果 实验了长方形和无延伸挡板及有特殊延伸挡板的条缝形吸气罩在不同罩口风速下对示踪气体的捕集效率。导出了捕集效率和距离的关系方程式。实验结果表明:(1)吸气罩与污染源的距离和罩口风速对捕集效率有明显的影响。当罩口风速一定时。吸气罩越靠近污染源,捕集效率越高;而在同一距离上,罩口风速越大,捕集效率就越高。(2)有延伸挡板的条缝形吸气罩的捕集效率高于无延伸挡板条缝形吸气罩,前者采用较低的罩口风速(抽风量)可以得到相应的高捕集效率。结论 使用示踪气体对吸气罩进行优选的结果表明,通过改进吸气罩的形式可以降低所需风量并达到要求的效率,从而为减少通风设施的费用提供了一种重要途径。     

吸尘罩的空气动力性能实验研究

目的 在粉尘发生源处设置适用的局部吸尘罩，是预防尘肺病的有效措施。为了提供适宜吸尘罩的设计，使用了示踪气体法进行优选，但所得到的吸气罩对示踪气体的捕集效率并不代表它对粉尘的捕集效率，因为粉尘有质量，有惯性。因此，在优选出的吸气罩基础上，应通过空气动力学实验，找出其罩口风速分布规律，根据产尘点的控制风速求出吸风量，并提供设计吸尘罩的必需数据。方法 在空气动力学实验台上测定了吸气罩罩口前中心线垂直断面和水平断面的风速分布以及吸气罩的阻力。风速、动压、全压分别采用了热电风速仪、皮脱管和倾斜式微压计测量。结果 (1)实验得出了有延伸挡板与无延伸挡板条缝形和方形吸气罩罩口中心线在垂直断面和水平断面的风速分布状况；(2)根据风速等速线分布，经分析归纳得出了有延伸挡板、无延伸挡板的条缝形、方形旁侧吸气罩罩口相对风速Vx／V0(无因次)和距离(距罩口)Xx／(A的平方根)(无因次)的关系方程式。利用该方程式在设定的控制风速下，可计算出吸气罩的风量；(3)结合玉石雕刻吸尘罩的设计，取产尘点的控制风速Vx=0．5m／s，采用有延伸挡板的条缝形旁侧吸气罩，利用上述方程式可计算出其抽风量Q1=255m^3／h；采用无延伸挡板的条缝罩或有延伸挡板方形罩，可计算出其抽风量分别为Q2=332m^3／h和Q3=360m^／h；前的风量分别为后二的77％和71％，为通风设计手册上砂轮吸尘罩的50％。结论 提供了几种吸尘罩的罩口风速分布规律及相应的计算方法，结合玉石雕刻吸尘罩的设计，揭示了优选出有延伸挡板的条缝形旁侧吸尘罩在玉石雕刻切割轮的最大产尘点处产生同样的控制风速，其抽风量仅为其他形式吸尘罩的77％-50％。这意味着使整套通风除尘系统(包括风管、除尘器、风机等)的初投资和运行费大大节省。因此，吸尘罩的优选设计是通风除尘系统设计中必须解决的关键问题。     

某采石工序局部通风除尘系统设计

目的对某采石场筛分工序的局部通风除尘系统进行设计,使工作场所空气中粉尘水平达到国家职业接触限值的要求。方法根据某采石场筛分岗位工艺特点及粉尘性质等基础资料,由工程通风设计人员以外部排风罩、通风管、风机选型和除尘器的选择为重点,设计局部通风除尘系统,安装后测定其粉尘控制效果。结果外部排风罩采用罩口尺寸为1.6 m×1.6 m的带法兰边框的上吸式排风罩,控制距离为1.1 m。除尘系统的总排(送)风量为148 072 m~3/h;风机的风量和风压分别为171 023 m~3/h和1 255.5 Pa;据此选择型号为4-79的普通中压风机和处理风量为186 000 m~3/h的WDJ47-3/1型WDJ型卧式电除尘器设备作为局部通风除尘系统。局部通风除尘系统安装实施后,筛分岗位空气中粉尘时间加权平均浓度为6.2 mg/m~3,低于国家职业接触限值8.0 mg/m~3。结论所设计的局部通风除尘系统达到设计要求。     

吸尘罩的优选及其在玉石雕刻防尘中的应用

目的对适用吸尘罩进行优选,并在实际通风除尘系统中应用。方法用示踪气体法对吸尘罩进行优选,比较不同吸尘罩捕集效率和风量的关系;对吸尘罩前风速分布进行测定,得出罩前风速分布模型。并对吸尘罩进行空气动力性能分析,测定雕刻排气中粉尘的粒径分级组成和除尘器的粉尘粒径分级除尘效率,评估除尘器的总除尘效率。结果优选出的雕刻吸尘罩,置于切割轮正前方0.11 m处,其控制风速为0.5 m/s,能有效地控制雕刻切割轮的粉尘不向周围扩散,工作地点空气粉尘浓度由无罩时的30-297 mg/m3降低至1.1-1.7 mg/m3,吸尘罩风量为255 m3/h,为其他类型吸尘罩的50%-77%。优选出的冲击水浴除尘器,其除尘效率为97%-98%,阻力为1.5 kPa;滤袋除尘器的效率为98%-99%,阻力为2.5 kPa;除尘后尾气的粉尘浓度为20-30 mg/m3。结论提出了优选吸尘罩的设计方法及实用的除尘器,可供实际应用。     

局部排风罩在不同行业中的设计及应用研究进展

排风罩是指设置在有害物源处,捕集和控制有害物的通风部件,局部排风系统的技术对其性能、经济效果具有很大的影响。本文通过对当前国内局部排风罩设计及应用特点、新型局部排风罩的应用前景分析,发现有毒有害作业场所设计安装的排风罩仍以传统的排风罩为主,类型以外部上吸罩、侧吸罩、下吸罩最为常见,而新型排风罩由于价格比较昂贵、抽吸的有毒有害物质有限等原因,尚未普及。综上,局部排风罩的设计与安装要在遵循基本设计原则的基础上,进行合理的成本效益分析,并把局部排风罩的利用效率最大化,充分论证其可能带来的长远社会效益。     

天津市某造船厂涂装车间吹吸式通风系统排风效果数值模拟研究

目的为改善涂装车间喷漆作业过程中甲苯等有毒物质浓度超标的现状,为涂装车间吹吸式通风系统的合理设计提供参考依据。方法 2018年9—12月以天津市某造船厂涂装车间喷漆作业为研究对象,运用FLUENT软件对涂装车间采用吹吸式通风时,不同排风口位置布置和不同送排风风量条件下的气流组织和甲苯的扩散规律进行数值模拟研究。结果数值模拟得出,采用吹吸式通风方式时,在送排风量相同的条件下,送排风口布置为上吹下吸时,有毒物质的控制效果优于上吹侧吸的送排风口布置形式。在排风量和送风量的比为1.5的条件下,送风风速为0.1 m/s和0.2 m/s时,待涂装工件两侧喷漆操作位甲苯质量分数在2.5×10~(-5)～4.0×10~(-5)之间;送风风速≥0.3 m/s时,甲苯的质量分数均2.0×10~(-5),平均值为1.25×10~(-5)。结论当涂装车间采用上吹下吸的吹吸式通风方式,且在排风量和送风量的比为1.5的条件下,送风风速为0.3 m/s时,最经济节能,同时有毒物质的控制效果较好,能够有效的降低喷漆作业人员接触有毒物质的浓度,保护劳动者的身体健康。     

热过程伞形排气罩的研究状况(综述)

本文介绍了国内外对热过程伞形排气罩的研究状况。热的有害物发生源处的温度与周围空气温度差别较大,在污染源周固有明显的对流气流,有害物质主要是依靠这股对流气流而传播,因之研究伞形排气罩扑集有害物质的问题就转而为研究这股对流气流的问题。早在40年代,Sutton就提出了点源上部所产生的对流气流速度及半径随距离而变化的关系式。50年代,Harch等人根据实验确定了热物体上的自由对流空气流的特性,并以所确定的关系式作为计算热过程伞形排气罩抽风量的基础,60年代Hemeon导出在热物体最上端的空气诱导量,从而确定了低悬伞形罩的最小抽风量公式。苏联中研究热板上的对流气流,得出了在热板表面不同高度处各截面上对流气流量的变化关系。70年代,日本林太郎等人通过试验确定了设计热过程伞形罩的“流量比法”。我所曾试验研究七种不同形状热源在伞形罩排气时热物体上的对流气流,提供了国内设计热过程伞形罩的基本数据。     

某公司丝网印刷机局部通风排毒系统改造前后效果评价

目的对某公司丝网印刷机局部通风排毒系统改造前后效果进行比较与评价,为今后改善类似作业环境提供依据。方法对丝网印刷室设备布局、存在的污染物种类进行分析;对丝网印刷机局部排风罩的罩型选择、设计、安装情况进行现场调研与分析;按照规定的方法对局部排风罩的罩口风速及控制点风速进行现场测试;对局部排风罩改进前后丝网印刷工序操作工位污染物浓度进行现场采样及分析。结果局部排风罩正确设计、安装及使用可以有效地提高控制效果;排风罩距污染物发生源的距离较远、罩口风速及控制点风速过低都会影响局部排风罩实际控制效果;罩口围挡可提高局部排风罩的控制效果;净化系统对污染物能否达标排放起到至关重要的作用。结论改造后局部通风排毒系统能够发挥正常功效,可以及时有效地将污染物捕集,通过净化系统将达标气体排放到大气中。     

水泥袋装车间粉尘控制模拟研究

目的分析并解决水泥包装车间粉尘危害治理问题。方法 2017年10月—2018年5月,以新疆某水泥生产企业袋装车间为研究对象,采用FLUENT数值模拟方法,对水泥厂包装车间现有通风条件粉尘扩散进行模拟研究。结果新疆某水泥生产企业袋装车间罩内通风系统设计不合理,造成包装车间和插袋工粉尘浓度超标分别为45.58、4.35倍(总粉尘)和20.68、2.87倍(呼吸性粉尘);在靠近尘源处、半密闭罩四角以及包装机后方风速较小,基本上在0.1～0.4 m/s,粉尘浓度较高,粉尘在呼吸带高度不同方位均存在不同程度的粉尘积聚;通过粉尘扩散模拟包装车间风流分布状况、粉尘扩散规律和通风控尘影响因素,袋装车间气流均匀性受通风设施风量、风口位置、风口大小等因素共同影响,通过不同方案组织优化模拟试验,最优方案插袋作业位置粉尘质量浓度在4～6 mg/m~3,较现有条件下粉尘质量浓度有明显下降,浓度在可接受范围内,气流组织最为合理。结论粉尘控制模拟研究达到水泥插袋岗位粉尘控制目的,有效解决了水泥包装车间粉尘危害这一问题,可为下一步开展水泥包装车间粉尘治理技术改造工作提供参考依据。     

某"三资"鞋业成型刷胶工序通风排毒效果评价

某“三资”鞋业是专门生产运动鞋的涉外企业,现有四条生产线,职工2200多人。1　成型生产线主要工序钉内底→刷帮面胶→结帮→刷处理剂→次刷胶→二次刷胶→合成→检验→成品包装2　通风排毒设施以刷帮面胶、刷处理剂、一次刷胶、二次刷胶、合成工序为冷源设置上吸式通风排毒系统,两条生产线共用一个通风机,使用Ｔ472Ｎ08Ｃ低压离心通风机,风量为28105ｍ3/ｈ。3　测试结果及评价经测定,在吸气罩下方(约20ｃｍ处),20个吸气罩控制风速在0.16～0.55ｍ/ｓ之间,罩口风速在0.7～3.2ｍ/ｓ之间,工人作业呼吸带空气中甲苯几何平均浓度在开启风机前为12…     

The optimization of Porous glasses for immobilized enzyme (IME) systems.

Critical parameters involved in the selection of porous glass for use as support materials in the immobilization of biologically active materials are discussed. The importance of physical properties such as pore morphology, surface area and particle size relative to the final activity of the enzyme is shown using glucoamylase IME as a model system. The process of selection of specific materials with respect to the environmental conditions of the enzyme and the chemical durability of the support is considered, as are the mechanical properties required in the scale-up of an application.     

Development and application of a model (ExDoM) for calculating the respiratory tract dose and retention of particles under variable exposure conditions

The ExDoM is a model for calculating the human exposure and the deposition, dose, clearance, and finally retention of aerosol particles in the respiratory tract at specific times during and after exposure, under variable exposure conditions. Specifically, the model incorporates an exposure module which allows the user to set variable or static exposure conditions (exposure concentration, physical exertion levels, and different environments) or in the case of the physical exertion levels and exposure environment to choose from a list of typical exposure scenarios (activity pattern, exposure environment, and physical exertion level). The exposure concentration can refer to total particulate matter (PM) concentration or chemically resolved particles of variant size distributions. The aerosol size parameters can be introduced to the model either directly as median aerodynamic diameter and geometric standard deviation or are estimated by the model from measurement data. The model treats monodisperse or polydisperse aerosol size distributions. The human respiratory tract (RT) model of the International Commission on Radiological protection (ICRP Publication 66) is utilized for the respiratory tract deposition calculations. The above together with the dose and clearance/retention modules can be used to study together exposure and dose of chemically resolved particles of variant size distributions. The ExDoM model implementation in order to study the exposure and dose of particles in the human RT is demonstrated at two locations. In particular, the dose and retention of particles to RT and the mass transferred to the gastrointestinal tract and blood capillaries are estimated for an adult Caucasian male exposed to PM₁₀ at a coastal remote site in the eastern Mediterranean. In addition, the regional lung doses of specific chemical components of PM₁₀ (inorganic ions and carbonaceous compounds) during realistic exposure conditions outdoors at a residential background area in Oslo, Norway, were assessed. The results from the two studies showed that the dose was enhanced for the carbonaceous fine fraction of particles in the alveolar region of the lung whereas the dose of crustal material dominated in the extrathoracic region.     

Effect of occupational exposures on male fertility: literature review

The present review was aimed to determine the influence of working conditions, occupational exposures to potential chemical and physical reproductive toxic agents and psychological stress during work on male fertility. Significant associations were reported between impaired semen parameters and the following chemical exposures: metals (lead, mercury), pesticides (dibromochlorophane, 2,4-dichlorophenoxyacetic acid), ethylene glycol ethers and estrogens. The following physical exposures were shown to deteriorate sperm parameters: radiation (both ionized and microwaves) and heat. Psychological distress has another important contribution to infertility. Several studies indicated that stress has a negative impact on sperm parameters. Occupational parameters should be an important part of history taking among patients attending infertility clinics.     

Modeling studies of the concurrent growth and neutralization of sulfuric acid aerosols under conditions in the human airways

A kinetic model of coupled droplet growth, gas uptake, and chemical reaction has been used to examine the possible changes to sulfuric acid aerosols as a result of exposure to respiratory ammonia under the conditions in the human airways. Results for a wide range of initial droplet sizes and concentrations spanning the extremes of likely atmospheric conditions are presented. It is predicted that gas phase reactions of SO2 will not significantly affect the neutralizing capability of airways ammonia. The effects of physical and chemical parameters on aerosol neutralization and growth are discussed and in particular, predictions of neutralization in typical inhalation times for aerosols characteristic of severe persistent London fogs and modern urban conditions are compared. The analysis supports the suggestion that the London fog episodes were unique in the relationship of the acid droplets formed to the neutralizing capability of ammonia in the human airways and that simple extrapolation of mortality and morbidity data from such episodes to modern conditions is unlikely to be valid.     

Consequences of chronic obstructive pulmonary disease and chronic heart failure: the relationship between objective and subjective health

This study investigates whether the relationship between objective health parameters and general health perceptions was mediated by symptoms of dyspnoea and physical functioning in patients with chronic obstructive pulmonary disease (COPD) and patients with chronic heart failure (CHF). The different health parameters were organised according to Wilson and Cleary's conceptual model of patient outcomes (Wilson & Cleary (1995). Journal of the American Medical Association, 273, 59-65). Second, we investigated whether perceptions of personal control were related to the health parameters in the model. Consecutive patients with COPD and CHF were included from the outpatient clinics of a university hospital and a general hospital, and from a rehabilitation centre, all in the Netherlands. Ninety-five COPD patients (aged 65.0+/-9.3; forced expiratory volume in 1s (FEV1)<70%) were included and compared with 90 CHF patients (aged 59.6+/-10.0; left ventricular ejection fraction (LVEF)<45%). The relationship between objective health parameters (FEV1 or LVEF) and subjective health (self-reported physical functioning) was not mediated by symptoms of dyspnoea. FEV1 or LVEF and symptoms of dyspnoea were independently related to self-reported physical functioning, which was directly related to general health perceptions. Perceived health competence was related to symptoms of dyspnoea and general health perceptions in patients with either COPD or CHF. Although patients with COPD reported lower levels in all self-reported health parameters in the model than the patients with CHF, this study showed that the relations between the health parameters in the model were comparable for COPD and CHF patients.     

苏州七子山垃圾填埋场渗滤液水量实验研究

目前,对山谷型垃圾填埋场渗滤液水量的计算尚无成熟方法.七子山填埋场建立了包括树冠截流、表土层调蓄作用等因素的水量平衡物理数学模型,采用小范围或典型点的实测或实验方法测定模型参数,并模拟大范围人工松杉林的水量平衡,对其物理数学模型和实验方法进行了验证.     

Mathematical modeling of the process of thermal action of the surface of human skin

The mathematical model of the physical system, which represents a pattern of a pulse heat source and a skin surface portion, is regarded as a dynamic process of thermal action on man. The model reflects a relationship of the parameters of a thermal pulse, the threshold characteristics of a thermoreceptor, and the thermal parameters of the skin.     

Individual physical performance capacity with physiological and biochemical indicators of stress

22 health male subjects were exposed by a combination of physical exercises and heat. Strain related physiological and biochemical parameters were measured. Different individual reactions were obtained under controlled conditions. In dependence on the individual performance an increased mobilisation of lactat, free fatty acids and catecholamines were found. The determination of aerob physical performance can be applied for the evaluation of working capacity.     

Model-aided characterization of Tenax-TA for aromatic compound uptake from water

The polymer adsorbent Tenax has been widely employed for studying desorption of organic contaminants in soils and sediments and for correlating physical availability with bioavailability. Although Tenax has been invoked to act as an infinite sink that completely and instantaneously removes solutes from the aqueous phase, to our knowledge no systematic characterization of Tenax resins has been carried out. The present study provides equilibrium and kinetic parameters for the uptake of benzene, nitrobenzene, naphthalene, phenanthrene, and pyrene by Tenax in selected water-solute-Tenax systems, and it offers guidelines for the use of Tenax resins. Sorption isotherms of the test compounds on Tenax-TA are nonlinear, and most show an inflection at high concentration, marking a change in physical state from glassy to rubbery. A simple dual-mode model was applied to the isotherms below the apparent inflection point. Sorption parameters for dissolution and hole-filling domains each correlate with the octanol-water partition coefficient. The effects of dissolved organic matter and salinity on Tenax-TA uptake are minor. Regeneration of Tenax-TA by hot-methanol extraction increased its affinity for naphthalene. Inclusion of 23% graphitized carbon in the polymer reduced affinity for phenanthrene. Uptake rate data were fit by the dual-mode diffusion model, which assumes diffusion in the polymer matrix. The obtained diffusion rate parameter correlates with molecular size. Equilibrium and kinetic parameters for benzene and nitrobenzene were comparable despite a three-orders-of-magnitude difference in their Henry's law coefficients, indicating that a pathway to the Tenax surface through the vapor phase is not required. Extrapolating to typical conditions in soil-desorption studies reveals that single-solute uptake is 95% or more complete within 4 min for the test compounds and within 7 min for benzo[a]pyrene. Thus, Tenax is suitable for compounds with desorption from soil or sediment that occurs over comparably longer timescales.     

Longitudinal study of the relation between environmental conditions and the health of patients in a long-stay hospital

A longitudinal survey has been conducted for a 30-month period in the long-term care hospital of Ivry, in Paris urban area. 1500 people were medically monitored daily by the doctors who were in charge of each unit of the hospital; each individual pathological event was exactly recorded, with complete development. This follow-up permitted to report 6300 acute illnesses. Environmental physical parameters (NOx, SO2, particulates, temperature, humidity, atmospheric pressure) were recorded indoors and outdoors during the whole period. The relation of environmental conditions to health has been studied with the cross-correlations method, applied to respiratory disease incidence rates and physical parameters series. It appeared that only NOx was significantly related to an increase of respiratory disease incidence rates.