The influence of biomass co-combustion on boiler fouling and efficiency

The paper presents an attempt to evaluate the influence of biomass co-combustion on the fouling of boiler convection surfaces. In order to show the influence of co-firing biomass with bituminous coal on boiler efficiency, the calculations of pulverized fuel (PF) OP 140 steam generator have been carried out. Typical Upper Silesian coal with medium fouling inclination has been chosen as a basic fuel. Three kinds of biomass have been taken into consideration: straw, wood and dried sewage sludge. The results confirm that the properties of additional fuels cause deterioration of the boiler efficiency as well as the changes in boilers operational parameters (amount of water injected in attemperators, ash stream, hot air temperature). The biomass during cofiring in fact replaces the coal, but always the additional fuel consumption is higher than that of the substituted coal. Therefore, the actual decrease of coal consumption is smaller than the thermal fraction of the biomass.     

分散锅炉房集中监测系统的开发与应用

为提高供热质量和设备运行管理水平,研制了分散锅炉房集中监测系统,研制成功被天津确认为天津市科研成果。     

Some considerations about bioethanol combustion in oil-fired boilers

The combustion of bioethanol in boilers has been analyzed and compared with conventional liquid fuels. The study includes an experimental evaluation of combustion performance as well as the estimation of the impact of replacing gasoil by ethanol on the thermal efficiency of an industrial boiler.Several works have been dedicated to the study of fuel substitution in internal combustion engines, being the use of gasoil-bioethanol blends in engines a common practice. However, very few studies have addressed the characterization of switching of conventional liquid fuels by bioethanol in boilers.Combustion tests demonstrate significant differences between bioethanol and gasoil flames. Soot, NO_x and SO₂ emissions are significantly lower with ethanol, whereas this fuel can produce higher amounts of CO than gasoil if the burner is not properly adapted. The experimental tests have demonstrated that both the burner and boiler operation should be readjusted or modified as a result of the change of fuel in industrial boilers. If thermal input is to be kept constant, nozzles of larger capacities must be used and the air feeding rate needs to be significantly modified. Also, the flame detector may have to be replaced and the fuel feeding system should be revised due to the enhanced tendency of ethanol to cavitation. Using the same thermal input may not guarantee keeping the same steam production, but some parameters of boiler operation should be modified in order to avoid reductions in the capacity of the boiler when switching from gasoil to bioethanol, such as gas recirculation fraction, steam cooling systems and percentage of oxygen in the exhaust gases.The feasibility of burning bioethanol in gasoil boilers has been analyzed, and the results confirm that fuel switching is technically possible and offers some advantages in terms of pollutants reduction.     

Biodiesel as alternative fuel: Experimental analysis and energetic evaluations

This paper presents the first results of an investigation carried out by the authors on the potentialities of biodiesel as an alternative fuel based on strategic considerations and field experiences in boilers and diesel engines.The operation of a biodiesel fuelled boiler has been checked for some months. The engines have been bench-tested and then installed on urban buses for normal operation. Distances, fuel consumption and emissions (CO₂, CO, HC and NO_X) have been monitored; in addition devices wear and tear, oil and air filters dirtiness and lubricant degradation have been checked.Further investigations have also been devoted to assess some environmental aspects of bio-diesel. In particular the benefit of biodiesel to the total net emission of CO₂ during the whole life cycle has been studied and the net energy requirement has been evaluated.Finally, the global environmental support to the production of biodiesel has been studied according to the emergy analysis.     

Smith预估在循环流化床协调控制中的应用

以某电厂210 MW机组循环流化床锅炉为例,对循环流化床机组协调控制系统存在的问题进行了分析,并结合循环流化床锅炉机组的特性,对所采取的Smith预估器在循环流化床协调控制中的应用进行了详细的研究和论证。     

国产670t／h锅炉经济性分析

针对部分国产670t／h锅炉经济性偏低问题,依据多年从事电站锅炉试验研究的经验和数据,从多方面对问题成因进行了分析,对今后锅炉节能降耗具有一定的参考意义。     

快装工业锅炉计算机辅助设计系统

本文叙述快装工业锅炉计算机辅助设计系统的结构、组成及各子模块的功能。     

锅炉干式排渣机低部冷却风门优化分析

本文介绍了某电厂干式排渣机系统运行中存在的问题,通过试验方法找到了解决方案,决定将干渣机低部冷却风门改造为电动调整门,达到优化机组运行参数、节能降耗的目的。     

A new use of boiler ash: recovery of vanadium as a catalytic VPO system

A VPO system was prepared from boiler-ash. VO(H₂PO₄)₂ phase has been obtained at low temperature and characterized through a combination of techniques including TG-DTA analysis, X-ray powder diffraction and FT-Raman spectroscopy. The thermal decomposition of the precursor material gives a VO(PO₃)₂ and V(PO₃)₃ phase mixture. Supported and unsupported catalysts prepared were compared and contrasted in the partial oxidation of methane (POM). The catalysts were more selective to C₂-hydrocarbons than a VPO catalyst prepared by the conventional method and studied in similar conditions. Thus, the selectivity to C₁-oxygenates was similar, however, the selectivity to CO_x products was hindered. The observation that the precursor VO(H₂PO₄)₂ obtained from boiler ash as recovery and precipitation of the vanadium can generate catalysts of low selectivity to total oxidation products might provide a useful insight into the design of a new series of high activity and high selectivity partial oxidation catalysts.     

Influence of Different Cleaning Conditions on Cleaning Performance of Pilot-Scale Pulse-Jet Baghouse

In this study, a pilot-scale pulse-jet baghouse is utilized to control the particulate emission of an oil-fired boiler. The operating and design parameters, such as filtration velocity, initial tank pressure, and nozzle diameter, were varied to evaluate the cleaning effect of the pulse-jet baghouse. Two different cleaning types, (1) high initial tank pressure and one bag cleaning; and (2) low initial tank pressure and two consecutive bag cleanings, are used to compare the bag-cleaning performance in this study. It is found that the cleaning effect increases with the initial tank pressure. However, the cleaning intensity (overpressure) does not increase with the nozzle diameter. There exists an optimum nozzle diameter to achieve higher cleaning intensity and a better cleaning effect. This phenomenon results from the small volume of the baghouse compartment in this study. If an industrial size baghouse was used, it suggests that a nozzle diameter larger than 13 mm and initial tank pressure greater than 2.5 kg/cm2 should be adopted to achieve a higher cleaning effect. Between the two cleaning types, type 2 is found to be more effective to clean the bag and the energy consumption for compressed air is reduced significantly from type 1. Therefore, type 2 bag cleaning is suggested to be a better method to clean the baghouse.