不同有机质污泥热水解直接脱水及厌氧消化潜力中试研究

在150～180℃条件下,利用中试实验设备,对不同来源浓缩污泥(TS约为20%)进行热水解中试实验,采用离心和板框脱水等两种方式对热水解后的污泥进行直接脱水,研究热水解温度,停留时间,污泥有机质含量等条件对污泥脱水性能的影响。选取170℃下保温60 min为最佳工况,高、中、低有机质组的污泥热水解后直接板框脱水,泥饼含固率可达到37.2%,39.8%和41.3%,同时通过对水解后的污泥,以及固液分离后的脱水液,泥饼分别进行厌氧产气实验(BMP),测定其不同热水解工况下混合相,液相,固相的产气性能,当实验开始3天后,液相甲烷产量即达到混合相最终甲烷产量的68%,72%,69%,证明了在中试条件上,热水解过程中,大部分可甲烷化有机物已转移至液相,且液相厌氧消化速度远大于固相,证明了污泥"热水解—脱水—脱水液厌氧消化"工艺路线的可行性。     

微生物电解池产甲烷技术研究进展

微生物电解池（microbial electrolysis cell,MEC）产甲烷技术是以微生物为催化剂,利用外界输入的电能将CO₂或有机污染物转化为甲烷的新技术。MEC在实现CO₂处置与能量转化的同时,能够处理污水、污泥、沼渣等多种污染物并生产甲烷,具有能量转化率高、生产成本低、环境友好等特点,可望成为解决能源紧缺和环境破坏问题的重要途径之一。近年来,MEC在产甲烷生物阴极结构及电子传递途径、产甲烷微生物群落等方面得到了广泛关注,同时,MEC耦合厌氧消化或其他废水处理系统形成的产甲烷新技术也逐渐研发并成为研究热点。本文综述了产甲烷生物阴极、产甲烷微生物群落等方面的研究现状,介绍了MEC耦合厌氧消化或其他系统产甲烷新技术,总结并分析了MEC产甲烷技术的研究方向和实用化过程仍需解决的技术难题。     

水热预处理对剩余污泥有机物释放的影响

针对剩余污泥中有机能源利用率低的问题,研究了水热预处理对剩余污泥有机物释放及污泥厌氧消化过程中累积产气量的影响。结果表明:水热处理是一种有效的污泥预处理方法,当水热温度为200℃、水热时间为1 h时,污泥减量度达76.56%,污泥SCOD为原泥的34倍,大大减少了污泥固相有机物含量。经水热处理后,污泥厌氧消化最大产气量为2 950 m L,较原泥提高了69%;厌氧消化后,水热预处理污泥SCOD减少量为原泥的30倍。     

隔膜压滤机在污泥脱水中的应用

隔膜压滤机是污泥脱水中的关键设备,通过对污泥脱水关键技术的研究,实现污泥生物沥浸技术突破与技术集成,采用隔膜滤板高压压榨的工艺提高污泥脱水效率,隔膜压榨工艺解决对厌氧消化过程中细胞壁难于消解等技术瓶颈问题。基于生物强化水解和物化强化水解的技术与设备,隔膜滤板压榨工艺提高污泥的水解效率和挥发性有机酸的生成率,实现污泥内含物的快速释放。隔膜滤板压榨压力设置3.5 MPa的使用压力,压榨后的泥饼含水率降为50%以下,泥饼改性为有机肥料可以焚烧发电转化为再生资源。     

微生物电解池产甲烷技术研究进展

微生物电解池(microbial electrolysis cell,MEC)产甲烷技术是以微生物为催化剂,利用外界输入的电能将CO_2或有机污染物转化为甲烷的新技术。MEC在实现CO_2处置与能量转化的同时,能够处理污水、污泥、沼渣等多种污染物并生产甲烷,具有能量转化率高、生产成本低、环境友好等特点,可望成为解决能源紧缺和环境破坏问题的重要途径之一。近年来,MEC在产甲烷生物阴极结构及电子传递途径、产甲烷微生物群落等方面得到了广泛关注,同时,MEC耦合厌氧消化或其他废水处理系统形成的产甲烷新技术也逐渐研发并成为研究热点。本文综述了产甲烷生物阴极、产甲烷微生物群落等方面的研究现状,介绍了MEC耦合厌氧消化或其他系统产甲烷新技术,总结并分析了MEC产甲烷技术的研究方向和实用化过程仍需解决的技术难题。     

叠氏污泥脱水技术处理炼油厂“三泥”

分析了炼油厂“三泥”性质和脱水预处理对策,介绍了叠氏污泥脱水机特点原理及处理炼油企业“三泥”的典型应用实例.当处理罐底泥时,进料含水率在86.7％～90.2％时,经叠氏污泥脱水机脱水后泥饼含水率降为54.2％～55.9％;当处理剩余活性污泥时,进料含水率在95.5％～97.5％时,经叠氏污泥脱水机脱水后泥饼含水率降为78.0％～79.0％;当处理浮渣时,进料含水率在90.5％～92.0％时,经叠氏污泥脱水机脱水后泥饼含水率降为67.9％～68.7％.所处理物料的脱水泥饼的含水率均低于80％,满足污泥迸一步处理前的脱水需求,与离心机相比节电在1/10以上.     

活性炭联合正弦波电场促进污泥脱水

利用活性炭联合正弦波电场促进污泥脱水,通过对泥饼电流、温度及泥饼、滤液的性质分析探究活性炭对污泥脱水的促进机理。结果表明,活性炭可以提升污泥导电性,增强污泥中的电化学反应,从而降低了泥饼含水率。在占空比为100%,投加量为5%污泥干重时,泥饼含水率为43%;活性炭可以吸附滤液中有机物组分,相比未投加,投加5%活性炭的总有机碳值降低了1.708g/L,降低了滤液处理成本。     

聚丙烯酸絮凝剂在印染污泥低温热处理中的应用

污泥脱水是实现污泥减量化和资源化利用的关键步骤。研究了自制聚丙烯酸絮凝剂PR在低温热处理条件下对印染污泥脱水性能的影响,探究其脱水机理。结果表明,PR能显著改善污泥的脱水性能。最佳工艺条件:PR用量15 mg/g,硫酸用量0.002 mL/g,75℃下热处理30 min。处理后污泥比阻降至2.80×10~(12) m/kg,降低了98.80%,泥饼含水率降至84.59%,结合水含量降至28.27%。     

温度对厌氧耗氢产甲烷的影响研究进展

化石燃料燃烧过程中大量排放的CO₂引起了人们对CO₂生物甲烷化的关注。厌氧有机物生物降解过程中，与CO₂生物甲烷化相关的主要是厌氧耗氢产甲烷菌。近年来，研究者们关注温度对厌氧耗氢产甲烷过程的影响，对推动厌氧耗氢产甲烷工艺的发展有着重要的意义。本文从厌氧耗氢产甲烷技术原理出发，介绍了厌氧生物降解过程中耗氢产甲烷菌的重要作用，归纳了32种仅利用H₂和CO₂产CH₄的专性耗氢产甲烷菌，展示了氢气可以来源于化石燃料、生物质、水的分解和工业气体，综述了不同温度范围下厌氧耗氢产甲烷的效能，总结了不同温度变化方式对厌氧耗氢产甲烷的影响，并从氢气来源和温度变化等方面提出了展望。     

白龙港污水厂污泥深度脱水设施的设计与试运行

上海市白龙港污水厂污泥深度脱水设施设计规模1500 t/d（以含水率80％计），采用三氯化铁、石灰化学调理和隔膜压滤处理工艺，经深度脱水后的污泥含水率小于60％。工程于2012年6月基本建成，7月起开始调试。通过4个月调试运行，污泥处理能力稳定达到300 tDS/d的设计规模，压滤机出泥泥饼含水率控制在60％以下，满足设计要求。     

Constant and Intermittent Drying Characteristics of Olive Cake

The drying kinetics of olive cake, the solid by-product of the olive oil extraction process, has been experimentally investigated in a small-scale tray dryer using both constant and intermittent (on/off) heating schemes. The parameters investigated include inlet air temperature and intermittency of heat input. The drying kinetics was interpreted through two mathematical models, the Page equation and the Lewis equation. The Page equation was most appropriate in describing the drying behavior of olive cake. A diffusion model was used to describe the moisture transfer and the effective diffusion coefficient at each temperature was determined. The dependence of the effective diffusion coefficient on drying temperature can be adequately explained based on an Arrhenius-type relation. The effective diffusion coefficient varied between 7.6 × 10^-8 and 2.5 × 10^-7 m²/min with an activation energy of 38.55 kJ/mol. Comparison of time evolution of material moisture content due to intermittent and constant drying is also made.     

Constant and Intermittent Drying Characteristics of Olive Cake

The drying kinetics of olive cake, the solid by-product of the olive oil extraction process, has been experimentally investigated in a small-scale tray dryer using both constant and intermittent (on/off) heating schemes. The parameters investigated include inlet air temperature and intermittency of heat input. The drying kinetics was interpreted through two mathematical models, the Page equation and the Lewis equation. The Page equation was most appropriate in describing the drying behavior of olive cake. A diffusion model was used to describe the moisture transfer and the effective diffusion coefficient at each temperature was determined. The dependence of the effective diffusion coefficient on drying temperature can be adequately explained based on an Arrhenius-type relation. The effective diffusion coefficient varied between 7.6 × 10^?8 and 2.5 × 10^?7 m²/min with an activation energy of 38.55 kJ/mol. Comparison of time evolution of material moisture content due to intermittent and constant drying is also made.     

Overall Energy Requisite and Quality Feature of Industrial Paddy Drying

Energy consumption and rice quality are the main concerns of millers and must be assessed to ascertain suitable industrial drying strategy. In this article, industrial paddy drying methods as usually practiced in the BERNAS paddy drying complexes of Malaysia have been evaluated. The analysis showed that the specific electrical and thermal energy consumption varied between 16.19 kWh to 22.07 kWh and 787.22 MJ to 1015.32 MJ, respectively, in single-stage paddy drying (SSPD) using an inclined bed dryer (IBD) to dry each tonne of freshly harvested paddy with average moisture content of 23.35 ± 0.86% wb. On the other hand, the energy consumptions for two-stage paddy drying (TSPD) with a fluidized bed dryer (FBD) followed by IBD were 21.37 kWh/t to 30.69 kWh/t and 666.81 MJ/t to 1083.42 MJ/t, respectively. SSPD at 35–39°C and TSPD using FBD at 120°C as the first stage, followed by IBD as the second stage at lower temperature of 35–39°C yielded 2–3.6% higher head rice yield than paddy-dried by a single stage with IBD using comparatively higher temperature of 40–44°C. Therefore, IBD is recommended to be operated using a temperature of 35–39°C both in single-stage drying and second-stage drying of paddy after fluidized bed drying to obtain quality rice.     

分散红146合成工艺改进

文章着重对分散红146的缩合工艺进行了改进,采用1-氨基-2-溴-4-羟基蒽醌潮品直接缩合,不但省去了原来烦琐的干燥工序和干燥设备、节省能源、降低生产成本,而且由于使用了溶剂进行脱水,其脱水更为彻底,不但滤饼中的水份能够完全脱尽,同时还能将缩合反应产生的水及辅助原材料中带入的微量水份一并及时馏出,加快了缩合反应速度,缩短了缩合反应时间,缩合温度也适当降低,减少了物料的焦化,不但产品质量得到明显提升,而且缩合收率也得到一定程度的提高。     

Simulation of Liquid Diffusion-Controlled Drying of Shrinking Thin Slabs Subjected to Multiple Heat Sources

Although a detailed mathematical model incorporating all physical mechanisms of moisture and heat transfer in the material would yield valuable design information, it is not feasible to do this on a routine basis for the design of dryers. A simple liquid diffusion model was developed in the present study to quantitatively assess the influence of various operating parameters of engineering interest in drying of heat-sensitive materials. Heat of wetting, temperature, and moisture dependent effective diffusivity and thermal conductivity, changes in product density and drying-induced ideal shrinkage of the product are considered in this model. The effects of combining convection with conduction, radiation, and volumetric heating using a microwave field are simulated in view of the increasing interest in multimode heat input drying processes. Numerical results are reported on drying of potato slices to demonstrate how the moisture and temperature profiles as well as drying performance are affected by multi-mode heat input. Effects of key parameters e.g., drying air velocity, temperature, relative humidity, and product thickness are computed and discussed.     

MOBILE FLUIDIZED BED PADDY DRYER

The objectives of this research are to design, construct and test a mobile fluidized bed paddy dryer with a drying capacity of 2.5-4.0 t/h. Suitable drying conditions are recommended as follows : drying capacity 3.8 t/h, bed velocity 2.8 m/s, average drying air temperature 144 °C, bed height 13.5 cm, fraction of air recycled 0.8. Residence time of paddy was approximately 1.3 minutes. Test results showed that moisture content of paddy was reduced from 32.6 % dry-basis to 25.8 % dry-basis. Consumption of electrical power and diesel fuel was 12.9 kW and 21.71 1/h respectively. Primary energy consumption was 910.9 MJ/h. The dryer could evaporate water 218.8 kg/h. Specific primary energy consumption was 4.2 MJ/kg-water evaporated. Cost of paddy drying was 1.48 baht/kg-water evaporated of which 0.53 was fixed cost and 0.95 was energy cost (US$1 =34baht).     

Upgrading of wakefield browncoal from south Australia

A sample of Wakefield browncoal, which is of very poor quality, was subjected to various treatments to improve the calorific value and remove contaminants. The best coal product, with a calorific value of 30 MJ/kg, was obtained by hydrothermal upgrading: 91% of the combustibles present in the feedstock were concentrated in 34% of the original weight. Moreover, an amount of liquid products was generated in a yield of up to 10 wt% on dry intake. Via a Fleissner treatment ca. 70% of the inherent moisture was removed as a liquid, leaving a product whose calorific value is expected to be almost 20 MJ/kg. Via carbonization smokeless fuels can be produced with a heating value of ca. 28 MJ/kg and yields of 50–60%, depending on the temperature. From this particular browncoal, most of the silica fraction of the mineral matter was extracted by rinsing with water, thus reducing the ash content by 50% and the ash fusion temperature by almost 200°C. By combined thermal upgrading and washing, most of the contaminants, i.e., sodium and chlorine, and half of the amount of oxygen and sulphur were removed. On the basis of experiments with micro-gasification test equipment, Wakefield browncoal and its upgraded product seem attractive feedstocks for gasification from a reactivity point of view. The lowering of the ash fusion temperature as observed in washed products is important for the reduction of the reactor outlet temperature when gasifying under slagging conditions, which has a favourable effect on the thermal efficiency.     

PREPARATION OF HYDROTHERMALLY TREATED LRC/WATER FUEL SLURRIES

The hot-water coal drying process is a means of thermally beneficiating and dewatering lignite and subbituminous coal for the purpose of preparing dense low-rank coal/water fuel. In hot-water coal drying, which is a form of hydrothermal treatment, low-rank coal in a water slurry is treated at elevated temperatures of 513 to 623  K and at pressures in excess of the equivalent saturated steam pressures lo minimize vaporization of the water. This produces a coal product which contains less than one-third the inherent moisture of the raw coal and which is resistant to moisture reabsorption. The hydrothermally treated coal/water slurry resulting from the process can be concentrated by mechanical means (centrifuge, pressure filter)to form a pumpable coal/water fuel with greater than 60 weight percent bone-dry solids content and with an energy content greater than 15·4 MJ/Kg (6600 Btu/lb). Hydrothermal treatment also beneficiates the coal by reducing oxygen and minerals. Over 94 percent of the energy content of the raw coal remains in the product. Low-rank coal/water fuel is typically a pseudoplastic fluid, and for some low-rank coals, the slurry is stable towards settling, without the use of additives.     

Simulation of Liquid Diffusion-Controlled Drying of Shrinking Thin Slabs Subjected to Multiple Heat Sources

Abstract

Although a detailed mathematical model incorporating all physical mechanisms of moisture and heat transfer in the material would yield valuable design information, it is not feasible to do this on a routine basis for the design of dryers. A simple liquid diffusion model was developed in the present study to quantitatively assess the influence of various operating parameters of engineering interest in drying of heat-sensitive materials. Heat of wetting, temperature, and moisture dependent effective diffusivity and thermal conductivity, changes in product density and drying-induced ideal shrinkage of the product are considered in this model. The effects of combining convection with conduction, radiation, and volumetric heating using a microwave field are simulated in view of the increasing interest in multimode heat input drying processes. Numerical results are reported on drying of potato slices to demonstrate how the moisture and temperature profiles as well as drying performance are affected by multi-mode heat input. Effects of key parameters e.g., drying air velocity, temperature, relative humidity, and product thickness are computed and discussed.     

MOBILE FLUIDIZED BED PADDY DRYER

ABSTRACT

The objectives of this research are to design, construct and test a mobile fluidized bed paddy dryer with a drying capacity of 2.5-4.0 t/h. Suitable drying conditions are recommended as follows : drying capacity 3.8 t/h, bed velocity 2.8 m/s, average drying air temperature 144 °C, bed height 13.5 cm, fraction of air recycled 0.8. Residence time of paddy was approximately 1.3 minutes. Test results showed that moisture content of paddy was reduced from 32.6 % dry-basis to 25.8 % dry-basis. Consumption of electrical power and diesel fuel was 12.9 kW and 21.71 1/h respectively. Primary energy consumption was 910.9 MJ/h. The dryer could evaporate water 218.8 kg/h. Specific primary energy consumption was 4.2 MJ/kg-water evaporated. Cost of paddy drying was 1.48 baht/kg-water evaporated of which 0.53 was fixed cost and 0.95 was energy cost (US$1 =34baht).