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As there are numerous coalbed methane (CBM) wells with low or zero gas production after traditional hydraulic fracturing in China, new technologies are needed for both the secondary stimulation of these wells and new wells’ stimulation. Based on the results of laboratory tests and theoretical analysis, this paper, the first of a two-part series, demonstrates the theory of a new combined stimulation...
Based on the theory and technology of combined stimulation, this paper, the second of a two-part series, presents an application of the combined stimulation technology to a low-deliverability CBM well in the Sunan Syncline, Anhui Province, China. During the stimulation, a low-damage fracturing fluid was adopted. Based on the laboratory test results, the property of the low-damage fracturing fluid...
Elemental analysis, CP/MAS 13C NMR, FTIR, XRD, XPS and ion-exchange experiment were used to study the structural characteristics of Longkou, Huadian and Yilan kerogens in an increasing order of humic degree. The relationship between their humic degree and structural characteristics was studied from three aspects: aliphatic structure, aromatic structure and heteroatom species (O, N and S). The results...
The influence of BaCO3 on chlorine fixation and combustion characteristics was investigated in a fixed bed system and thermal analyzer. Both simulation and experimental results show the stability of BaCl2 was much better than CaCl2 at temperature higher than 800°C. The chlorine fixation of cotton stalk was improved 5.35 times by BaCO3. The barium chlorides in the ashes were mainly BaCl2 and Ba(ClO...
The influences of pyrolysis temperature and phosphorus additives on physico-chemical quality and combustion property of bio-char briquettes were investigated in this research. Bio-char briquettes were obtained from directly pyrolysis of maize straw briquettes. Pyrolysis temperature were from room temperature to 250–650°C with a heating rate 10°C/min. Combustion tests were performed in a thermal-gravimetric...
Crystallization inside the liquid slag of entrained flow gasifiers can increase the viscosity of the slag, affecting flow down the wall and resulting in operational problems. The chemical component of the slag is an intrinsic factor of crystallization characteristics. In the study presented here, Differential Scanning Calorimetry (DSC) and the Single Hot Thermocouple Technique (SHTT) were combined...
Simultaneous imaging of OH∗ chemiluminescence and Mie scattering of fuel spray have been performed under reacting conditions in a constant volume combustion chamber aimed for a second-generation biodiesel/diesel blended fuel. Mie scattering of 532nm laser light technique was used for the liquid fuel measurement. In order to remove the interference signal from soot radial, filtered Mie scattered light...
Coal is an important fossil energy. In order to improve its use efficiency, the study of its complex structure has drawn much attention all over the world. Since 1942, lots of molecular level models of coal have been proposed. However, they cannot reflect the yield distribution of benzene carboxylic acids (BCAs) that are generated from coal by oxidation. In this work, the organic matter structure...
OH plays a leading role for Hg0 removal. The simultaneous removal efficiencies of Hg0, SO2 and NO are up to 100%, 100%, 85.3% and 100%, 100%, 75.3% using Fe3+ and Cu2+ as catalysts, respectively.
The polarity of asphaltenes influences production, transportation, and refining of heavy oils. However, the dipole moment of asphaltene molecules is difficult to measure due to their complex composition and electromagnetic opaqueness. In this work, we present a convenient and efficient way to determine the dipole moment of asphaltene in solution by dielectric measurements alone without measurement...
The structure and transformation of fused aromatic ring system in asphaltenes play an important role in the character of asphaltenes, and in step affect the properties of heavy oils. Polarity, solubility and structural characteristics of asphaltenes derived from Tahe atmospheric residue (THAR) and Tuo-826 heavy crude oil (Tuo-826) were analyzed for study of their internal relationship. A fractionation...
The three-dimensional (3D) dynamics of a propane diffusion flame was investigated using high speed stereo imaging and a newly developed stereoscopic schlieren techniques. The laminar flame is kept at a flow rate of 0.3slpm, which corresponds to a mean exit flow velocity of 0.30m/s and a low Reynolds number at 300. The flame shows a typical flickering phenomenon at 11Hz. The 3D dynamics of the visible...
An innovative 3D flame visualisation and digital reconstruction technique was developed on the basis of digital flame colour enhancement and conventional stereo reconstruction methods. This combined methodology, together with Schlieren visualisation technique, was utilized to investigate the ignition process of propane impinging diffusion flame. Through the application of flame colour analysis, it...
Based on two-film theory, the mass transfer–reaction kinetics of NO absorption from flue gas by using UV/H 2 O 2 /NaOH process was investigated in a photochemical reactor. The effects of several operating parameters on NO absorption rate were studied. The mass transfer-reaction process of NO absorption was analyzed. A simple NO absorption rate equation is also established and tested...
Using nonlinear theory as guidance, the expected (both reported and unreported) nonlinear response modes of a laminar diffusion flame to external acoustic excitation are investigated at different frequencies (6–100Hz). The flame oscillating frequency is analyzed using digital signal and image processing techniques, while the hot gas dynamics are visualized by a high speed schlieren imaging system...
The experimental investigation of impinging diffusion methane (CH 4 ) and propane (C 3 H 8 ) ignition-to-combustion process under varying fuel flow rates and ignition positions have been characterised through multi-dimensional Digital Flame Colour Discrimination (DFCD) incorporated image processing methods. The DFCD post-processed digital flame images revealed that a 2D bluish-green...
The experimental investigation of the dynamic flame flickering properties of acoustically excited combustion process has been conducted. In particular, the variations of flame oscillation frequency response in diffusion-like sooty and premixed-like chemiluminescence flame colour entities under external acoustic perturbation were extracted, analysed, and compared using digital colour image processing...
Measurement of laminar burning velocity of dimethyl ether–air mixtures was taken under different initial pressures and equivalence ratios using a constant volume bomb and high-speed schlieren photography. The stretched laminar burning velocity increases with the increase of stretch rate. At equivalence ratio of 1.0, low initial pressure gives high stretched flame speed. At initial pressure less than...
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