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Waste liquid treatment is widely concerned with the deepening of people's awareness of environmental protection, especially for the waste liquid with a high chemical oxygen demand (COD), which also has a high calorific value and makes it possible for the incineration treatment. In this study, the pyrolysis and combustion characteristics of pesticide waste liquid (PWL) are investigated by using thermogravimetric experiment and kinetic analysis, and the effects of different water and salt contents on its pyrolysis and combustion are discussed. The results show that both pyrolysis and combustion processes of the simulated pesticide waste liquid (sPWL) could be divided into two stages. As the water content increases from 0% to 18.5%, the volatilization characteristic index of stage Ⅰ (low temperature) increases by 263.31%, while that of stage Ⅱ (high temperature) decreases by 28.32%, and the water content could promote the pyrolysis and comprehensive combustion performance of the sPWL. As the sodium chloride contents increase from 0% to 1.5%, both the pyrolysis and combustion process of the PWL are enhanced, and the volatile release characteristic index, the ignition temperature and burnout characteristic index increase by 60.77%, 18.74% and 47.95%, respectively. By the means of the Coats-Redfern integral method, the kinetics of the pyrolysis and combustion of the PWL are analyzed, with a linear correlation coefficient of more than 95%. In a whole, a suitable water and sodium chloride content in the pretreatment process is crucial for efficient and low-cost treatment of waste liquid, which can promote the pyrolysis and combustion processes. These results are expected to provide several insightful guidance for the efficient treatment of the waste liquid. • The pyrolysis and combustion characteristics of pesticide waste liquid are studied. • The effects of the water and salt contents in pesticide waste liquid are analyzed. • The pyrolysis and combustion process of waste liquid is divided into two stages. • Water can promote pyrolysis and improve the combustion of the waste liquid. • The sodium chloride in waste liquid should be controlled in the pretreatment stage. [ABSTRACT FROM AUTHOR]

Coal-fired power plants remain a significant source of CO 2 emission, NH 3 /coal co-firing in existing coal-fired boilers can rapidly and effectively reduce CO 2 emissions. However, the unique physicochemical properties of NH 3 result in unstable combustion and high NO x emissions. Superfine pulverized coal combustion and moderate or intense low-oxygen dilution (MILD) combustion are two advanced technologies with stable combustion and low NO x emissions. This study systematically investigated the coupling of these two technologies in NH 3 /coal co-combustion. Results show that the synergistic effect of superfine pulverized coal and MILD combustion ensures stable NH 3 /coal flame propagation, with a shorter lift-off distance and a higher peak temperature (70 K–100 K increase) under higher NH 3 blending ratio (NBR) conditions. As the NBR increases from 0 to 40 cal%, the maximum Da s-O2 for the superfine particles (18 μm) decreases from 0.55 to 0.49, while for normal particles (125 μm), it decreases from 3.9 to 3.4. The combustion state of superfine particles more easily approaches the MILD combustion state. The value of R char-H2O /R char-CO2 increases from 0.64 to 1.93, indicating the C Char -H 2 O reaction dominates the char gasification behavior. Compared to that for normal particles, the NO emission concentrations for superfine particles combustion at 0, 10 cal% and 20 cal% NBR were reduced by 48 %, 64 % and 47 %, respectively. These findings provide new insights and theoretical guidance for stable combustion and low NO x emissions of NH 3 /coal co-firing. [Display omitted] • Coupling MILD with superfine particle combustion in NH 3 /coal co-firing is proposed. • The combustion state of the superfine particle is closer to the MILD regime. • C Char -H 2 O reaction dominates the char gasification behaviors at high NBRs. • The NO emission of superfine particles are lower than those for normal particles. [ABSTRACT FROM AUTHOR]

• Revealing the fuel-NO formation mechanism affected by CO 2 and H 2 O dilutions. • CO 2 dilution favors maintaining MILD combustion regime in an expanded reaction zone. • Free radical level is weakened by CO 2 while H 2 O boost the formation of OH radical. • The lowest overall NO emission is derived under MILD-H 2 O combustion. • H 2 O dilution enhances the N radical formation and inhibits HNO direct conversion into NO. MILD-oxy combustion operates conventional oxy-combustion processes under moderate or intense low-oxygen dilution (MILD) condition, which offers a practical approach towards the synergetic control of CO 2 and NO x emissions. This numerical work investigates the MILD combustion characteristics and NO emission of CH 4 /NH 3 fuel blend under N 2 , CO 2 and H 2 O dilutions, aiming at revealing the fuel-NO formation mechanism under MILD-oxy condition. It is found that relative to MILD-N 2 combustion, the flame temperature is reduced under MILD-CO 2 and MILD-H 2 O combustion, while the reaction zone is expanded and reduced, respectively, due to the altered co-flow properties. CO 2 dilution lowers the radical pool level, while the formation of OH radical is boosted under H 2 O dilution. Overall NO emission (EINO) under MILD-N 2 combustion is the largest while that under MILD-H 2 O generates the lowest value, showing its low-NO x emissions superiority. NH 3 is converted into NO via routes NH 3 → NH 2 → HNO → NO and NH 3 → NH 2 → NH → HNO → NO under MILD-CO 2 combustion. By contrast, the importance of route NH 3 → NH 2 → NH → N → NO in producing NO is largely strengthened under MILD-H 2 O combustion, wherein the direct formation of NO via HNO is inhibited with the enhanced availability of reactive N-containing species, contributing to lower NO emission under MILD-H 2 O combustion over MILD-CO 2 combustion. [ABSTRACT FROM AUTHOR]