Emission of pollutants from wood waste incineration at sawmills in Abeokuta metropolis,Nigeria

This paper reports an assessment of the effects of wood waste burning on air quality and the perceived human health in an urban setting. The concentrations of particulates and selected gases were monitored within the vicinity of sawmills in Abeokuta metropolis. The levels of CO, CO₂, SO₂, NO_x, NO₂, H₂S, CH₄ and particulates at distances from sawmill dumps were measured using portable samplers. Additionally, information on sawmill operations and health problems encountered by the exposed population were collected from a community survey. From the data analyses, between 60 and 100% of wood waste generated by sawmills were burned openly, leading to pollutants emission. The mean concentrations of PM_0.3–0.5 (32 523–40 284 μg/m³), NO₂ (1.0 ppm), SO₂ (3.3 ppm), CO (759 ppm) and CO₂ (4.9%) were higher than the permissible limits at 0–15 m from the dump sites. Almost all sampled parameters showed positive association (R = 0.90–0.98; p < 0.05) at sample sites. Moreover, distance of sites to the dumps explained 51–93% of the variation in parameters levels. Both respiratory and dermal diseases were frequently experienced by the exposed population. Strict land-use zoning, pollution abatement measures, environmental quality monitoring and waste-to-energy interventions are urgently required in the study area.     

Performance validation of a hybrid ventilation strategy comprising longitudinal and point ventilation by a fire experiment using a model-scale tunnel

We examined the exhaust performance of a hybrid ventilation strategy for maintaining a safe evacuation environment for tunnel users in a tunnel fire. The hybrid ventilation strategy combines the longitudinal ventilation strategy with the point ventilation strategy which is a type of transverse ventilation strategy. The model tunnel developed by this study was scaled to 1/5 the size of a full-scale tunnel. The model-scale experiment was performed taking into consideration Froude's law of similarity. Measurement items were the distribution of temperature and concentration of smoke inside the tunnel, longitudinal wind velocity, mass flow of smoke in the point ventilation duct, and the heat release rate of the fire source. The following main conclusions were obtained. The smoke height was constant even when varying the extraction rate of smoke from the ceiling vent. The backlayering length and critical velocity of the smoke flow in the hybrid strategy could be predicted by the methodology developed by using the longitudinal strategy. The hybrid strategy maintained a safe evacuation environment on both sides of the tunnel fire.     

Study on the real-time size distribution of smoke particles for each fire stage by using a steady-state tube furnace method

For the analysis of the adverse effects of smoke on health, it is essential to determine the amount and location of smoke particles deposited in the respiratory tract. However, the deposition characteristics of the particles are influenced by their morphology and size distribution. Moreover, the real-time particle size distribution during inhalation is important for determining smoke particle deposition in the lungs. Smoke particles generated under different fire conditions differ in their physical and chemical characteristics. Thus, there is a need to adopt international standard methods for characterizing the particles generated in fire. In the present study, the size distributions together with morphology of smoke particles were measured for each fire stage by using the steady-state tube furnace method given in ISO/TS 19700. The size distributions of smoke particles from wood and polypropylene (PP) were measured in real time by using an electric low-pressure impactor (ELPI⁺), and their morphologies were analyzed using transmission electron microscopy (TEM).     

净化厂房排烟设置的几点建议

厂房内的工艺设备造成排烟管道着火，火势顺着排烟管道蔓延至技术夹层及屋面，造成技术夹层及屋面相关设备、系统完全损毁。建议风管（特别是工艺排风管道）穿过设备及风管密布的技术夹层时加设防火阀，且技术夹层设置机械排烟系统。     

张家港大厦空调通风系统设计

张家港大厦是高层全封闭的四星级宾馆 ,设有完备的智能空调系统。大厦由3台螺杆冷水机组提供冷源 ;由3台燃油蒸汽锅炉提供热源 ,考虑到突发事故检修的要求 ,循环水泵采用并联系统。一到四层的大空间采用定风量空调系统 ;标准层采用新风机组加风机盘管空调系统。在防排烟设计中 ,根据国内外消防的经验和教训 ,大厦的消防电梯井采用加压防烟的设施。空调系统由大厦的BAS系统统一控制。本文最后总结了大厦的运行调试经验     

激光光斑尺寸对烟幕干扰效果影响的研究

为了提高激光武器抗烟幕干扰的能力，通过利用相关理论进行推导和计算，分别得出施放烟幕前后目标表面光斑尺寸的大小与探测器接收到的来自目标的激光功率以及烟幕干扰效果之间的关系，以模拟烟幕对激光武器的干扰效果评估。验证了理论推导和计算基本符合实际情况。研究表明，光束的半径越小，能量越集中，烟幕对激光武器的干扰效果越差，激光武器的抗干扰能力越强。     

Smoke concentrations inside and outside of a corridor-like enclosure

This work presents smoke measurements and correlations inside and outside of a corridor-like enclosure fires in order to determine the effects of burning on smoke concentrations inside and outside the enclosure. Thirty eight experiments were performed in a three metre long corridor-like enclosure having a cross section 0.5 m×0.5 m, door like openings in the front panel and a gaseous burner located near the closed end. Smoke concentrations were measured at two locations inside the enclosure and also in the exhaust duct of a hood collecting the fire gases from the enclosure. It was found that smoke concentration in the exhaust duct decreased whereas smoke concentration inside the enclosure increased after the flames started moving towards the opening and external burning occurred. This increased smoke concentration inside the enclosure was caused by reversion of the flow pattern inside the enclosure after the flames moved past a point towards the opening. Namely, the flow pattern changed direction behind the flame front in the sense that hot gases in the upper layer were travelling backwards towards the closed end of the corridor thus contributing to smoke increase inside the enclosure. This change of flow pattern was confirmed in all experiments by bidirectional probe velocity measurements in the upper and lower layer as well as by oxygen concentrations and temperature measurements inside the enclosure. These results are useful for CFD validation and specifically applicable for assessing smoke hazards in corridor fires in buildings where smoke concentrations can be much larger than anticipated owing to leakage to adjacent rooms behind a moving flame front.     

袋式除尘器与电除尘器在选型方面的比较

从工艺要求，基建投资和维修难易方面对袋除尘器和电除尘器进行比较，为设计选型提供依据和参考。     

低烟无卤阻燃色条光缆的研制

本文主要介绍了低烟无卤阻燃色条光缆的研制，包括该产品的护套工艺流程、低烟无卤阻燃护套料的性能、对挤出机的要求、烘干工艺、温度控制、色母料配比、色条缆模具设计等。     

Influence of fire ignition locations on the actuation of smoke detectors and wet-type sprinklers in a furnished office

Experiments were conducted in a full-scale model office equipped with movable and fixed fire loads to explore the influence of ignition source (movable fire load(s)) conditions on smoke detector and sprinkler actuation. The interior plan dimension is 5.7 m × 4.7 m and the net ceiling height is 3.3 m. Both northeast and southeast wings have a 2.1 m × 0.9 m single door to be opened. Seven fire scenarios (seven different ignited fire load configurations) under natural ventilation were investigated experimentally. The results show that the amount of fire load at the initial stage in a room fire does not markedly affect smoke generation and does not significantly impact the actuation time of the smoke detectors. When the fire source is located near a corner, the plume corner effect greatly increases; smoke detectors and sprinklers can activate quickly and effectively actuate the fire suppression. When the fire source is located in the room's center, given the uncertainty regarding smoke detector and sprinkler actuation, it may not be possible to control the fire spread.