Channel: Energy Conservation and Environmental Protection https://www.hdpower.net EN-US https://www.hdpower.net/EN/2097-0706/current.shtml https://www.hdpower.net 2097-0706 https://www.hdpower.net/EN/10.3969/j.issn.2097-0706.2024.08.006 Hydrolysis process limits the anaerobic digestion 锛圓D锛� rate of sludge. Supplementing exogenous biochar 锛圔C锛� can effectively boost methane production by overcoming the limitation in hydrolysis. The iron-manganese modified biochar 锛團e-Mn-BC锛� derived from the residual shells of woody oil crops锛� specifically Camellia oleifera shells锛� is studied. SEM锛� FTIR锛� XPS and XRD are employed to characterize the material锛� and its impacts on sludge AD performance锛� methane yield and microbial community structure are explored. The study results demonstrate that since Fe-Mn-BC possesses a porous structure锛� iron and manganese particles can load onto the BC surface in various forms of oxides. The addition of Fe-Mn-BC elevates methane production. When the total solid mass fraction of Fe-Mn-BC reaches 80 mg/g锛� cumulative gas production peaks at 301.59 mL/g锛� marking a 45.27% increase compared to that of the control group. Microbial community analysis reveals that Fe-Mn-BC enriches the abundance of archaeal communities锛� including Crenarchaeota锛� Candidatus_Methanomethylicus and Candidatus_Methanofastidiosum. These communities play crucial roles in promoting the hydrolysis of organic matters and enhancing the methane production锛� indicating that Fe-Mn-BC not only enriches functional microbial communities such as methanogenic bacteria锛� but also effectively improves the efficiency of sludge AD. Furthermore锛� this method presents a resource utilization solution for Camellia oleifera shells.

]]> https://www.hdpower.net/EN/10.3969/j.issn.2097-0706.2024.08.007 Taking a 660 MW opposed firing boiler as the study object锛宼he combustion features and distribution of alkali metals in the furnace during co-combustion with dehydrated sludge are studied by numerical simulation锛宎nd the influence factors including the blending layer锛� excess air coefficient and different Cl content in sludge are analyzed. The co-combustion with dehydrated sludge will increase the alkali metal mass concentration on the furnace side wall. The study indicates that blending sludge on the middle and upper layer of the burner can reduce the emission rate of alkali metals and lower the wall temperature near OFA nozzles. Increasing excess air coefficient can improve the burnout rate of pulverized coal and reduce the alkali metal mass concentration on the side wall. And decline of the Cl content in sludge can effectively reduce the concentration of alkali metals in flue gas and conversion rate of alkali metal compounds to NaCl. Blending sludges on the middle and upper layers of a co-combustion burner can reduce the excess air coefficient and alleviate the fouling锛� slagging and alkali metal high temperature corrosion in the furnace.

]]> https://www.hdpower.net/EN/10.3969/j.issn.2097-0706.2024.08.008 The furnace temperature of a multi-pass circulating fluidized bed锛圕FD锛� is higher than that of a traditional CFD锛� which advances the miniaturization of CFDs. The gas-olid flows and combustion of a multi-pass CFD were numerically stimulated by computational particle fluid dynamics method. The simulation results fitted well with the results of the pilot-scale experiment. The results indicate that volume fractions of particle phase show core-annulus structure锛� ranking from high to low in the main combustion chamber锛� auxiliary combustion chamber锛� and burnout chamber. The furnace temperature is from 1 000 to 1 200 K. The temperature of the main chamber is higher larger than that of the auxiliary chamber锛� and the temperature of the auxiliary chamber is higher than that of the burnout chamber and the cyclone separator. Increasing the oxygen content in the dense phase zone of the furnace by enlarging the proportion of primary air to secondary air can intensify the combustion and increase the bed temperature. Pre-classification of fuel at the secondary chamber inlet is beneficial for coke reduction reactions锛� which is favorable to the reductions of NO concentration and nitrogen oxide emissions.

]]> https://www.hdpower.net/EN/10.3969/j.issn.2097-0706.2024.08.009 As an important component of an integrated energy system锛� a CHP unit not only provides electric and thermal power锛宐ut also lays a foundation for renewable energy consumption. The fan and coal mill are significant devices for a cogeneration unit and play vital roles in its operation. In the research on fault diagnosis technologies锛宖aults in fans and coal mills are summarized锛宎nd subsequently锛� based on artificial intelligence algorithms锛宼he fault diagnosis technologies are categorized into three technical approaches锛� machine learning锛� deep learning锛� and hybrid models. The development trends and core issues of each technology are analysed. Finally锛� the prospects of fault diagnosis technologies applying in integrated energy systems are discussed.

]]> https://www.hdpower.net/EN/10.3969/j.issn.2097-0706.2024.08.010 Making reliability evaluations on selective catalytic reduction锛圫CR锛� denitrification systems in thermal power plants is significance for the safe operation of denitrification systems. Based on the classification on failure causes of denitrification systems锛宎 fault tree analysis锛團TA锛� taking abnormal ammonia/nitrogen molar ratio as its main indicator is applied on the evaluation. Then锛� Boolean algebra is used to analyze the path set of the FTA fault indicator锛寃ith a total of 11 minimum cut sets and a total of 5 minimum path sets. Considering the combination modes and propagation paths of impacts of elementary events on top events锛宎n evaluation method for system safety hazards according to confidence degree is proposed. Based on the operational data of a denitrification system in a 300 MW unit boiler锛宎 failure probability analysis was carried out on a specific fault of the reactor锛宎nd the conclusion was reached that the relative error between the confidence degree of the minimum cut set K7 and the confidence degree of the reliability evaluation method was only 0.694%. And the relative errors of other 20 fault events were all within 1%. The results show that the proposed evaluation method based on the minimum cut set confidence is accurate and feasible.

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