Plasma fixed bed gasification using an Eulerian model

Gasification of solid waste is considered as a green and sustainable solution to perform energy recovery from several waste streams. This work aims to adapt an Euler-Euler multiphase mathematical model to understand the effects of physical and chemical factors, i.e. equivalence ratio (ER), steam to fuel ratio (SFR), and input plasma power of municipal solid waste (MSW) fixed bed gasification. The model is capable of simulating temperature and velocity fields, as well as gas and solid composition variations inside the reactor. A two-step pyrolysis model is used considering the pyrolysis mechanism of cellulose and plastic components. Drying, pyrolysis, homogeneous gas reactions, and heterogeneous combustion/gasification reactions were also included in the model. It was shown that the proposed model could provide accurate predictions against experimental data with a deviation generally lesser than 10%. Conclusion could be drawn that an ER of 0.3 and an SRF of 0.5 seems to be the most favourable conditions in order to obtain a high-quality syngas. Higher plasma power is favourable to obtain a high-quality syngas. However, the high electric power required penalizes the process efficiency and may compromise the economic viability of a plasma gasification project.     

Performance assessment of thermal power plant load control system based on covariance index

This paper proposes a novel method of performance assessment for load control system of thermal power unit. Load control system is the most important multivariable control system. It is necessary to monitor and evaluate the performance of it. The performance evaluation index system based on covariance is defined, and the performance evaluation rules are given. In MATLAB, the double input and double output object model of the load control system is established, and the dynamic characteristics of the load control system are analyzed under the BF and TF mode. The simulation data, which is based on the parameters retuning, is used as the “benchmark data”, and the simulation data of different controllers are collected as “monitoring data”. For most of the time, the thermal power plant is under the coordinated control mode, and the principle and strategy of the two coordinated control are analyzed, and the engineering realization scheme is given. Operation data in different time periods of two different thermal power plants was acquisition and preprocessing respectively. The principle of selecting “benchmark data” is the minimum of pressure parameter. Two data segments were selected as “benchmark data”, performance assessment and analysis was carried on the data from other time periods. The results show that the validity and reliability of the method based on the evaluation index. In short, the data of the simulation and the load control system of power plant are used to demonstrate the effectiveness of the method.     

大型磷复肥装置磷石膏湿排干堆工艺与技术剖析

针对磷复肥生产排放大量磷石膏带来的堆存和环境问题,并应运而生了湿排干堆技术,认为本行业普遍选用的翻盘和转台两种真空过滤机都可改造为双加料双卸料的满足湿排干堆工艺要求.从返回的残余渣和冲洗水、维护工作量,运行稳定性和节省能耗等方面分析,认为双加料双卸料的翻盘真空过滤机更适用于磷石膏湿排干堆工艺,并在湖北省大型磷复肥装置中得到了推广应用.     

印染厂节能减排实用工艺装备技术(二十四)——印花固色的节能减排

热平衡测算发现,目前印花固色的蒸化机有效热能仅占总热能的20.24%,而无效的排汽热损失高达61.27%;采用蒸化织物含水率控制可减少蒸汽消耗40%～50%,减少总含氮量排放50%～65%,实现少尿素、无尿素印花工艺。     

GSP气化技术煤粉密相输送系统稳定性研究

为实现大规模工业化GSP气化技术煤粉密相输送系统的稳定输送,研究了煤粉物性、输送工艺、操作参数对输送特性的影响。结果表明:当煤粉湿含量由6.9%降到4.2%时,锁斗下料顺畅,减压系统偶尔出现堵塞。采用压差控制输送煤粉时,煤粉质量流量波动大于20 t/h,而采用流量调节控制煤粉输送时,煤粉质量流量波动小于5 t/h,因此,采用流量调节控制时,煤粉输送稳定性大幅提高。当操作参数进料器流化气量由220～180 m3/h调整为90～140 m3/h时,煤粉输送管线注射器1气体的流量由7 m3/h调整为3 m3/h,投煤后关闭注射器2,可使固气比由280 kg/m3增加到400 kg/m3,质量流量由42 t/h增加到72 t/h,进一步提高了煤粉密相输送系统的稳定性。     

青藏±400 kV格尔木换流站户内直流场厂房屋面结构型式论证

通过对格尔木±400 kV换流站工程中户内直流场厂房屋面采用不同的结构型式，从结构受力、造价预算和施工工期等方面的分析比较，提出经济可行的屋面结构型式，为同行进行类似设计时提供参考。     

Energy and exergy analyses in drying process of non-hygroscopic porous packed bed using a combined multi-feed microwave-convective air and continuous belt system (CMCB)

This paper is concerned with the energy and exergy analyses in the drying process of non-hygroscopic porous packed bed by combined multi-feed microwave-convective air and continuous belt system (CMCB). Most importantly, this work focused on the investigation of drying phenomena under industrialized microwave processing. In this analysis, the effects of the drying time, hot-air temperature, porous structure (F-Bed and C-Bed) and location of magnetron on overall drying kinetics and energy utilization ratio (EUR) were evaluated in detail. The results showed that using the continuous microwave application technique had several advantages over the conventional method such as shorter processing times, volumetric dissipation of energy throughout a product with higher energy utilization and less exergy efficiency in drying process. The results presented here provided fundamental understanding for drying process using CMCB in industrial size.     

Thermal power plant efficiency enhancement with Ocean Thermal Energy Conversion

In addition to greenhouse gas emissions, coastal thermal power plants would gain further opposition due to their heat rejection distressing the local ecosystem. Therefore, these plants need to enhance their thermal efficiency while reducing their environmental offense. In this study, a hybrid plant based on the principle of Ocean Thermal Energy Conversion was coupled to a 740 MW coal-fired power plant project located at latitude 28°S where the surface to deepwater temperature difference would not suffice for regular OTEC plants. This paper presents the thermodynamical model to assess the overall efficiency gained by adopting an ammonia Rankine cycle plus a desalinating unit, heated by the power plant condenser discharge and refrigerated by cold deep seawater. The simulation allowed us to optimize a system that would finally enhance the plant power output by 25–37 MW, depending on the season, without added emissions while reducing dramatically the water temperature at discharge and also desalinating up to 5.8 million tons per year. The supplemental equipment was sized and the specific emissions reduction was estimated. We believe that this approach would improve the acceptability of thermal and nuclear power plant projects regardless of the plant location.     

Biotechnological potential of industrial wastes for economical citric acid bioproduction by Aspergillus niger through submerged fermentation

Submerged citric acid (CA) bioproduction was carried out by Aspergillus niger NRRL‐567 using various industrial wastes, such as brewery spent liquid (BSL), lactoserum and starch industry water sludge. CA bioproduction was carried out by varying the temperature (25–35 °C), pH (3–5), addition of inducers, incubation time and supplementation with different proportions of apple pomace ultrafiltration sludge (APS). The results indicated that under the best conditions with 3% (v/v) methanol, the optimal concentration of 11.34 g L^?1 CA was recorded using BSL at pH 3.5 and temperature 30 °C after 120‐h incubation period. Supplementation of methanol resulted in an increase of 56% CA production. Meanwhile, under similar conditions, higher concentration of 18.34 g L^?1 CA was reported with the supplementation of BSL with 40% (v/v) APS having suspended solids concentration of 30 g L^?1. The present study demonstrated the potential of BSL supplemented with APS as an alternative cheap substrate for CA fermentation.