Search

This article proposed an original comprehensive thermal treatment coupled with gasification and combustion (CGC) of oil sludge (OS), which was designed to produce hydrogen-rich syngas. Based on the experimental results of OS gasification with steam, the combustion characteristics of char from OS gasification were analyzed by thermogravimetric experiments under different heating rates of 10, 20 and 30 °C/min. The combustion process of OS gasification char can be divided into three stages, including water evaporation, volatile combustion and heavy component combustion. The average values of activation energy (E) obtained by Friedman, FWO and Starink methods were 89.98 kJ/mol, 147.61 kJ/mol and 143.09 kJ/mol, respectively. According to OS gasification and OS gasification char combustion experiments, the comprehensive thermal treatment process CGC of OS was simulated by Aspen Plus. The simulation results showed that increasing both gasification temperature and the mass ratio of steam to OS (SOS) could promote the hydrogen production. Considering energy consumption, the recommended OS gasification temperature, SOS and char combustion temperature were 800 ∼ 900 °C, 0.3 ∼ 0.5, and 900 ∼ 1000 °C, respectively, which could ensure full burning of char and reduce the generation of pollutants. The CGC process could reduce CO2 emissions by 44.2% from carbon flow analysis. [ABSTRACT FROM AUTHOR]

Oil sludge is a typical hazardous waste in the petrochemical and electric power industry. It has complex components and special properties, and has serious hazards to humans, plants, water, and soil. Therefore, how to realize the effective disposal of oil sludge has become an urgent issue to be solved worldwide. Among the existing oil sludge treatment approaches, combustion has been considered to be a promising technology to realize the large-scale industrial application. In the present work, the characteristics of oil sludge were described in detail. The application and development of oil sludge combustion technology were critically summarized and discussed, including factors affecting combustion, drying process, combustion characteristics, synergistic treatment technology, and formation and control of secondary pollution. Besides, the development of combustion equipment, and integrated thermal treatment technology for oil sludge were prospected. This work can be used for guiding the industrial disposal of oil sludge. [ABSTRACT FROM AUTHOR]

Combustion of High-sulfur oil sludge (OS) blended with CaO can significantly reduce the emission of sulfur gas pollutants, but its combustion and kinetic characteristics need to be further studied. TGA experiments showed the combustion characteristics of OS were significantly changed after adding CaO. As reflected by comprehensive combustion index (S), the combustion performance of OS decreased after adding CaO, and significantly improved with the increase of heating rate. The kinetic parameters of the main combustion process of OS with CaO were calculated by the iso-conversion methods of Friedman, FWO, and Starink, respectively. Kinetic analysis results indicated the energy required for OS combustion with CaO first increased and then decreased with deepening of reaction degree. The thermodynamic parameters of ΔH, ΔG and ΔS were determined on the basis of kinetics. The negative ΔH, positive ΔG, and negative ΔS validated the combustion of OS with CaO was an exothermic and nonspontaneous process. [ABSTRACT FROM AUTHOR]

Oil sludge (OS) is a typical dangerous waste in petroleum industry, which also contains abundant energy. The purpose of this study was to recover resources from OS gasification. To figure out the gasification process, a thermal analyzer was used to carry out OS gasification experiments under steam/nitrogen atmosphere with different heating rates. Results showed that the OS gasification reaction could be divided into five stages: free water volatilization, the escape of light components, the cracking of heavy components and steam reforming, the charring process and water gas shift (WGS) reactions, and inorganic mineral decomposition. The activation energy (E), pre‐exponential factor (A), enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS) of three main reaction stages (Stages 2–4) were analyzed through kinetic and thermodynamic analysis. From Stage 2 to Stage 4, E, ΔH, and ΔS decreased from 118.80 kJ·mol−1, 113.92 kJ·mol−1, and −4.09 J·(K mol)−1 to 13.19 kJ·mol−1, 5.92 kJ·mol−1, and −234.06 J·(K mol)−1, respectively. Nevertheless, ΔG increased from 116.01 to 210.04 kJ·mol−1. From these parameters, it could be found that the decrease of E was beneficial to the reaction. However, the values of ΔG were always positive and the reaction could not happen spontaneously. [ABSTRACT FROM AUTHOR]

• Integrated thermal treatment of OS was designed and simulated using Aspen Plus. • Thermal and exergy efficiency of the process were analyzed and discussed. • The thermal and exergy efficiency of the system was 61–68% and 56–71%, respectively. • System's efficiency reached the maximum when pyrolysis temperature was 650 °C. An integrated thermal treatment (coupled pyrolysis and combustion) of oil sludge (OS) was proposed for enhancing the OS resource utilization. According to the pyrolysis experiment results, the integrated thermal treatment process of OS was modeled and simulated using Aspen Plus. Carbon flow, heat distribution, energy flow, energy efficiency and exergy efficiency of the process were analyzed and discussed. The results indicated that the simulation values were consistent with the experimental ones within the pyrolysis temperature of 00–780 °C With the increase of pyrolysis temperature, the carbon flow of pyrolysis oil was firstly increased and then sharply decreased, and the maximum value was achieved at 600–650 °C. Carbon flow of pyrolysis gas was initially increased rapidly followed by a continuously decreasing growth rate, and then increased sharply above 650 °C. The maximum heating value of pyrolysis oil was obtained at 600 °C. When pyrolysis temperature exceeded 650 °C, both the pyrolysis gas production rate and the gas heating value were improved. The energy and the exergy efficiency of the system can reach values as high as 61–68% and 56–71%, respectively, and the maximum efficiencies were achieved at the pyrolysis temperature of 650 °C. The present work could provide valuable insights towards promoting the development of effective OS utilization processes in the near future. [ABSTRACT FROM AUTHOR]

Integrated thermal treatment (coupled pyrolysis and combustion) is considered to be an effective method for the utilization of oil sludge (OS). Characteristics of OS pyrolysis, OS combustion and OS char combustion were comprehensively investigated with a thermogravimetry-mass spectrum (TG-MS) system in this work. Small molecule hydrocarbons like CH 4 were main components in OS pyrolysis gas. Nitrogen and sulfur containing compounds, H 2 O, and CO 2 were detected out during OS and OS char combustion. The maximum intensities of NH 3 , HCN and NO all appeared in the OS combustion. H 2 S was the main precursor of SO 2 , and the peak of H 2 S occurred earlier with an increase in the pyrolysis temperature between 500 and 700 °C. Besides, with an increase in the pyrolysis temperature, NO 2 and SO 2 emissions increased during OS char combustion. [ABSTRACT FROM AUTHOR]

Experimental and simulation studies on the migration characteristics of heavy metals during the incineration of OS were conducted with a tube furnace reactor and thermodynamic equilibrium calculation software FactSage, respectively. The results showed that when the incineration temperature increased from 800°C to 1100°C, the release rates of heavy metals such as Cr, Pb, Cu, Zn and Ni increased gradually and reached the maximum at 1000°C. When the excess air ratio increased from 1.0 to 1.4, the release rates of heavy metals such as Cr, Pb, Cu, Zn and Ni first decreased and then became steady. The content of gaseous hydroxide of Cr and gaseous chlorides of Pb and Cu increased while the chemical forms of Zn and Ni did not change obviously with the increase of combustion temperature or excess air ratio. [ABSTRACT FROM PUBLISHER]

Hydrogen can be prepared by oil sludge (OS) gasification with steam, which is of great significance for industrial hazardous waste treatment and resource conservation. The gasification performance was studied by a tube furnace reactor. The OS gasification was carried out at different temperatures (600, 700, 800 and 900 °C) and with different steam to OS ratio (SOS) (0.1:1, 0.3:1, 0.5:1). During the gasification process, hydrogen production first increased and then decreased, and hydrogen production was faster in 5–15 min. The yield of hydrogen of OS gasification reached the maximum when the SOS was 0.3:1 at 800 °C. The highest hydrogen yield per unit mass OS was 48.50 mL min−1 g−1. After gasification, the char yield was high, generally more than 50%. It was necessary to treat the char and incineration was an effective solution for low carbon fuels. Thus particle size distribution, incineration thermogravimetric analysis and heavy metal leaching concentrations analysis were carried out. The results showed that the average particle size of char ranged from 85 to 120 µm. The char incineration process could be divided into three stages: water evaporation, the precipitation and combustion of volatiles, and the combustion of fixed carbon and heavy components. After OS gasification at 800 °C, the leaching concentrations of typical heavy metals (As, Cr, Cu, Ni, Pb and Zn) were all up to the standard. Therefore, OS gasification combined with char incineration was an effective approach for the utilization of solid waste, which can recover hydrogen energy and reduce environmental risks. [Display omitted] • Gasification of oil sludge with steam atmosphere was comprehensively investigated. • The characteristics and distribution of gas production were studied. • The incineration characteristics of gasification residues were studied. • Gasification and incineration coupling could complete treatment of solid waste. [ABSTRACT FROM AUTHOR]

• Low temperature pyrolysis of oil sludge was comprehensively investigated. • Effect of catalysts on distribution of pyrolysis products was studied. • Catalysts significantly reduced the potential ecological risk in pyrolysis chars. • Catalysts promoted the transfer of hydrocarbons from gas to oil products. The pyrolysis performance of oil sludge (OS) was studied using a thermal gravimetric analysis apparatus and a tube furnace reactor. The oil recovery rate of OS pyrolysis showed a rapid growth trend at 450 °C. Moreover, the co-pyrolysis experiments of the OS and catalysts, including walnut shells, Fe 2 O 3 , K 2 CO 3 , polyvinyl chloride (PVC), and OS pyrolysis char with addition ratios of 5, 7, and 9 wt%, respectively, were conducted in a tube furnace reactor at 450 °C. The experiments demonstrated that all catalysts increased the oil recovery rate, but the optimal addition ratios differed. The pyrolysis chars produced above 450 °C had a well-developed pore structure, and the catalytic pyrolysis of OS at 450 °C could increase the yield of pyrolysis oil and reduce the potential ecological risk of heavy metals in the pyrolysis char. Therefore, catalytic pyrolysis is an inexpensive and highly efficient approach for treating solid waste. [ABSTRACT FROM AUTHOR]

The development of waste-derived adsorbent is of great significance to realize the idea of "treating waste with waste". Herein, a novel porous activated carbon was synthesized from oil sludge waste (OSAC) in a facile way. The resultant OSAC possesses favorable properties such as high specific surface area (324.98 m2 g−1) and abundant surface oxygen-containing functional group, which contribute to outstanding adsorption capabilities for Methylene Blue (MB, 316.02 mg g−1) and Direct Blue 6 (DB, 124.24 mg g−1) dyes. The adsorption capacity of OSAC is closely related to the initial solution pH since the surface charge state of the adsorbent is affected by pH values. With the increasing of pH values, the adsorption capacity of MB raised while that of DB decreased. The adsorption isotherms, kinetics, thermodynamics analyses have been investigated. Although the Langmuir model and the pseudo-second order model fitted well to the experimental data for both dyes and the thermodynamic parameters revealed their adsorption processes were all endothermic and spontaneous, the adsorption mechanism of the two dyes is not exactly the same. In addition to the difference of physical adsorption caused by dyes molecular size, the difference in chemical adsorption effects due to the different charge properties of the two dyes was also an important aspect of the adsorption mechanisms. Moreover, the reutilization analysis shown a presentable recyclability of the OSAC. It is demonstrated that the strategy developed here would provide cost-effective production of adsorbents for treatment of dye wastewater and offer a promising avenue of fabrication of high-value-added products from hazardous industrial waste. [ABSTRACT FROM AUTHOR]