Development of a catalytic dehalogenation (Cl,Br) process for municipal waste plastic-derived oil

Dehalogenation is a key technology in the feedstock recycling of mixed halogenated waste plastics. In this study, two different methods were used to clarify the effectiveness of our proposed catalytic dehalogenation process using various carbon composites of iron oxides and calcium carbonate as the catalyst/sorbent. The first approach (a two-step process) was to develop a process for the thermal degradation of mixed halogenated waste plastics, and also develop dehalogenation catalysts for the catalytic dehydrochlorination of organic chlorine compounds from mixed plastic-derived oil containing polyvinyl chloride (PVC) using a fixed-bed flow-type reactor. The second approach (a single-step process) was the simultaneous degradation and dehalogenation of chlorinated (PVC) and brominated (plastic containing brominated flame retardant, HIPS–Br) mixed plastics into halogen-free liquid products. We report on a catalytic dehalogenation process for the chlorinated and brominated organic compounds formed by the pyrolysis of PVC and brominated flame retardant (HIPS–Br) mixed waste plastics [(polyethylene (PE), polypropylene (PP), and polystyrene (PS)], and also other plastics. During dehydrohalogenation, the iron- and calcium-based catalysts were transformed into their corresponding halides, which are also very active in the dehydrohalogenation of organic halogenated compounds. The halogen-free plastic-derived oil (PDO) can be used as a fuel oil or feedstock in refineries.     

三种典型的污泥发电工艺

污泥发电是城市污水处理厂进行污泥合理开发利用的技术措施之一,是污泥实行减量化、稳定化、无害化、资源化的良好方法,本文介绍了3种典型的污泥发电工艺：污泥焚烧发电;污泥厌氧消化产生沼气、通过燃气轮机组发电;污泥厌氧消化产生沼气、进而通过改质制造氢气,经燃料电池发电。对污泥合理利用的规范化、科学化有一定的借鉴意义。     

Measuring environmental degradation by using principal component analysis

The objective of the paper is to measure environmental degradation on the basis of some selected indicators by the application of a simple multivariate technique known as Principal Component Analysis. For this purpose the study considered six variables, namely, GDP per capita, fuel consumption, total fertility rate, water supply, sanitation, and electricity. However, because of unavailability of data, the variables such as technology relating to environment, waste disposal, air pollution, women/gender issues relating to environment, corruption, democracy etc. could not be considered. The results show that principal components explain about 62% of the variations in the level of environmental degradation. The variables like GDP per capita, fuel consumption, water supply and electricity played a major role in classifying the countries in terms of environmental degradation compared to the variables, sanitation and total fertility rate. The findings show that countries which have high GDP per capita, low fuel consumption, higher percentage of people having access to water supply and sanitation as well as electricity ranked higher in terms of environmental quality despite high fertility rate as shown by the spectacular example of Saudi Arabia. By contrast, those countries which have low percentage of population having access to safe water and sanitation as well as electricity, high fuel consumption and high fertility were ranked lower in terms of environmental quality despite high per capita income, as shown by the example of Angola which is placed in lowest position among the 51 selected countries. The results also show that correlation between poverty and environmental degradation is particularly acute in African countries where high population growth is acting as an exacerbating factor. The study concluded that high fertility has much impact on environmental degradation in case of poorer countries than in case of rich countries.

Prediction of flammability limits of fuel-air and fuel-air-inert mixtures from explosivity parameters in closed vessels

Flammability limits of fuel-air and fuel-air-inert gaseous mixtures, especially at non-atmospheric conditions, are essential properties required for establishing safety operating conditions for handling and processing flammable gases. For pure fuels, an important data pool exists, formed by the flammability limits of fuel-air and fuel-air-inert gaseous mixtures at ambient initial conditions measured by standard methods. Such methods can be used for experimental determination of flammability limits for multi-fuels mixed with air, with or without additives, under non-atmospheric conditions. Their use is however a time- and material-consuming process; in addition, the flammability limits obtained by various standard methods may be scattered as a result of different choices in the operating parameters, for each standard method. It appears that a preliminary estimation of the flammability limits for fuel-air and fuel-air-inert gaseous mixtures can minimize the effort of measuring them in specific initial conditions.The present paper describes a new method for estimating the flammability range of fuel-oxidizer gaseous mixtures based on measurements of explosivity properties e.g. the peak explosion pressure and maximum rate of pressure rise recorded during closed vessel laminar explosions of fuel-oxidizer mixtures far from limits. Data obtained for several hydrocarbon-air gaseous mixtures with or without inert gas addition are used to examine the accuracy of estimated flammability limits (LFL – the lower and UFL – the upper flammability limit) as well as of the Limiting Oxygen Concentration (LOC) and the Minimum Inert Concentration (MIC). The predictive ability of the proposed method is examined against the predictive ability of other recently described methods.     

广西苍梧马尾松林和大叶栎林的火行为比较

马尾松(Pinus massoniana)是中国南方大面积造林的树种,也是抗火能力最弱的树种。研究了广西苍梧11龄马尾松用材林和4龄大叶栎萌芽林在正常冬季和干旱夏季情景下的火行为,用behaveplus计算了火线强度、蔓延速度、树冠火可能性等参数。结果表明,两种林分在干旱夏季的火行为高于在正常冬季的火行为。无论是在正常冬季还是在干旱夏季,都没有出现马尾松可燃物模型的火行为一致高于大叶栎可燃物模型的情况;天气、地形、可燃物床结构对可燃物含水率有很大影响,而含水率是火行为的决定因素。虽然大叶栎被划分为难燃树种,大叶栎萌芽林的火行为高于成年大叶栎乔木林,苍梧大叶栎萌芽林在极端干旱的夏季情景有被火把点燃的可能性。如果将大叶栎萌芽林作为防火林带使用,需要经常清除林下枯枝落叶,割除黑莎草,减少细小可燃物。     

Biomass waste gasification - can be the two stage process suitable for tar reduction and power generation?

A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kW_th. The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950 °C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar compound contents confirmed superiority of the two stage gasification system, drastic decrease of aromatic compounds with two and higher number of benzene rings by 1-2 orders. On the other hand the two stage gasification (with overall ER = 0.71) led to substantial reduction of gas heating value (LHV = 3.15 MJ/Nm³), elevation of gas volume and increase of nitrogen content in fuel gas. The increased temperature (>950 °C) at the entrance to the char bed caused also substantial decrease of ammonia content in fuel gas. The char with higher content of ash leaving the second stage presented only few mass% of the inlet biomass stream.     

Numerical Analysis of Heat Transfer and Gas Flow in PEM Fuel Cell Ducts by a Generalized Extended Darcy Model

Abstract

In this work, gas flow and heat transfer have been numerically investigated and analyzed for both cathode/anode ducts of proton exchange membrane (PEM) fuel cells. The simulation is conducted by solving a set of conservation equations for the whole domain consisting of a porous medium, solid structure, and flow duct. A generalized extended Darcy model is employed to investigate the flow inside the porous layer. This model accounts for the boundary-layer development, shear stress, and microscopic inertial force as well. Effects of inertial coefficient, together with permeability, effective thermal conductivity, and thickness of the porous layer on gas flow and heat transfer are investigated.     

Tar-free fuel gas production from high temperature pyrolysis of sewage sludge

Pyrolysis of sewage sludge was studied in a free-fall reactor at 1000–1400 °C. The results showed that the volatile matter in the sludge could be completely released to gaseous product at 1300 °C. The high temperature was in favor of H₂ and CO in the produced gas. However, the low heating value (LHV) of the gas decreased from 15.68 MJ/N m³ to 9.10 MJ/N m³ with temperature increasing from 1000 °C to 1400 °C. The obtained residual solid was characterized by high ash content. The energy balance indicated that the most heating value in the sludge was in the gaseous product.     

The effects of Orimulsion and Fuel Oil #6 on the hatching success of copepod resting eggs in the seabed of Tampa Bay,Florida

A 3-month microcosm study was conducted to observe the potential effects of two fuels, Orimulsion and Fuel Oil #6, on the hatching success of copepod resting eggs in the seabed of Tampa Bay, Florida. Microcosms were dosed with one of five hydrocarbon treatments via hydrocarbon-coated sand and compared with controls. Acartia tonsa eggs were nonviable in all treatments after only a few weeks of incubation, as evidenced by a marked decline in the abundance of nauplii. However, there was no evidence that exposure to simulated spills of 700 or 7000 ppm of either fuel led to significant increases in resting egg mortality as compared with controls. The results further indicate that, regardless of environmental conditions, resting eggs of A. tonsa do not remain viable in the sediment for extended periods of time.