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In order to meet the current environmental protection ultra-low pollutant emission requirements, one-step combustion is changed into two-step combustion by split-phase gasification combustion technology, and double-furnace structure, graded air distribution, calcium injection desulfurization, and combined denitrification with selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) are adopted to reduce pollutant emissions. ansys was used to establish a two-dimensional steady-state structure model of pulverized coal boiler with a double-furnace. Finite element analysis was carried out on the combustion in 54 MW, 56 MW, and 58 MW working conditions under different calcium-sulfur (Ca/S) ratios. The results showed that the desulfurization efficiency increased gradually when the Ca/S ratio was between 1.0 and 2.6 under the three working conditions. The desulfurization efficiency has no noticeable change when it is between 2.6 and 2.8, and begins to decline when it is greater than 2.8. The optimal calcium-sulfur ratio is obtained when the calcium-sulfur ratio is 2.6, and the SO2 concentration at the outlet of the furnace is reduced to 0.0001 mg/m3. By controlling the highest temperature in the furnace and adjusting the amount of denitrification agent, the nitrogen oxide emission at the outlet of the furnace is reduced to 0.87 mg/m3.

To expound the mechanisms responsible for the effect of electrolyte on the interfacial tensions (IFTs) of mixed solutions containing zwitterionic surfactant alkyl sulfobetaine (ASB) and anionic sur...

Extended surfactants have shown great potential in enhanced oil recovery (EOR). In this paper, the effects of extended surfactant concentration, polypropylene oxide (PO) number, and various counter ions (Na+, Ca2+, and Mg2+) on the oil-water interfacial tension (IFT) of extended surfactant solutions were investigated in detail. The selected extended surfactants were sodium dodecyl polyoxypropylene sulfate (L-C12POmS, m=5, 10, 15). Based on our experimental results, under NaCl conditions, with an increase in the PO number, the space occupied by the surfactant molecules on the side of the oil phase increases, which matches the size of the anionic head, and the surfactant film becomes tight. An ultralow IFT value appears for L-C12PO15S at 0.5% NaCl against decane. The addition of bivalent cations can significantly reduce the IFT. As the Ca2+ concentration increases, IFTs of APS solutions against alkanes can achieve ultralow values at lower PO numbers and against alkanes with a wide ACN range. For the MgCl2 system, the smaller hydration radius of Mg2+ improves the tightness of the anionic head, resulting in a crowded arrangement of the PO chains on the oil phase side. Therefore, the ability of Mg2+ to reduce the IFT against alkanes is weaker than that of Ca2+. Moreover, the surface-active substances in the crude oil adsorb competitively on the interface, resulting in an increase in IFT. By adding Ca2+or Mg2+, a tight adsorption film of surfactant molecules will be formed, and the IFT value reaches ultralow against crude oil. The studies in this paper have important implications for the application of extended surfactant solutions to enhance oil recovery under high salt reservoir conditions.

To expound the mechanisms responsible for reducing interfacial tensions (IFTs) in amphoteric and ionic surfactant mixed systems, the IFTs of mixed solutions containing alkyl sulfobetaine (ASB) and different ionic surfactants against hydrocarbons with different carbon numbers have been investigated by the spinning drop method. For cationic surfactants, the antagonistic effect for reducing IFT appears between cationic and ASB molecules because of electrostatic repulsion, which results in competitive adsorption. On the other hand, the synergistic effect will be observed in ionic and ASB mixed systems as a result of the mixed adsorption caused by the electrostatic attraction. The “chain length compatibility” between the anionic surfactant and ASB molecules leads to a stronger synergistic effect and further reduces IFT. However, “size compatibility” plays the crucial role, and only mixed solutions containing an anionic surfactant with a larger hydrophobic group can produce ultralow IFT against hydrocarbons. Th...

Open-cell foams consisting of interconnected struts are widely used in thermal applications such as volumetric solar receivers. The thermal performance of foams strongly relies on their radiative behaviors which intrinsically depends on the radiative properties of struts. This study proposed a feasible approach to determine the radiative properties of solid struts by a pore scale identification from a macro scale measurement. First, the normal-hemispherical transmittance and reflectance spectra of two nickel foams were measured by an experimental system. Second, a pore scale forward calculation was conducted by a combination of Monte Carlo Ray-tracing method and real foam structures obtained from micro-computed tomography technique. Last, an Adaptive Particle Swarm Optimization algorithm was adopted to retrieve the spectral reflectivity and specularity of nickel struts from the measured spectra. The results show that it is unreasonable to assume the reflection behavior of strut surface simply as either specular or diffused, and also, it is unreliable to assign the reflectivity of strut surface directly by Fresnel's law. Within the investigated wavebands 0.4–2.2 μm, the average reflectivity of nickel struts is 12% lower than that of a nickel mirror. The proportion of specular reflection at nickel strut surface is between 37%–52%, almost increasing with wavelengths.

Betaines and anionic-nonionic surfactants are suitable for applying in enhanced oil recovery (EOR) in the high-temperature and high-salinity reservoir conditions. We have used the spinning drop method to investigate the interfacial tension (IFT) values of alkyl carboxylicbetaine (ACB) and five types of anionic-nonionic surfactant (C14E3C, C16E3C, C18E3C, C18E5C and C18E10C) with different ethylene oxide (EO) numbers and different alkyl chain lengths against hydrocarbons and crude oil. Thereafter, under the same conditions, the IFT values of ACB and anionic-nonionic surfactant mixed solutions have also been investigated. The experimental results exhibit that for achieving ultralow IFT the proper hydrophilic-lipophilic balance (HLB) is prerequisite, but the tightness of the adsorption film is the key factor, which is controlled by the consistency of the spaces occupied at the oil side and the water side of an interface. This mechanism is so called “size compatibility”. The ultralow level IFTs have been reached during wider concentration ranges as the mixed systems against crude oil, which have not happened when the hydrocarbons are the oil phase. These phenomena demonstrate the strong synergistic effect among ACB, anionic-nonionic surfactant and natural surface-active materials, which is important for the development of high-temperature and high-salinity oil reservoirs.

High-temperature radiative properties of open-cell foams are relatively scarce due to measurement limitation. This study aims to numerically predict the volumetric radiative properties of irregular open-cell foams at high temperatures. The prediction is based on established relations which link the volumetric radiative properties to the structural parameters and/or component optical/radiative properties. Four typical foams are considered, including copper foams, nickel foams, zirconia foams and alumina foams. Former two are made of opaque metals, while latter two are made of semitransparent oxidized ceramics. For the four foams, the highest temperatures investigated are up to 1084 K, 1605 K, 1633 K and 2300 K, respectively. The variations of radiative properties with wavelength and temperature are analyzed. It was found that high temperature can strengthen radiation absorption inside metal and ceramic foams at most of wavebands. The temperature has almost no influence on the scattering phase function of metal and ceramic foams. Compared to copper foams, the nickel foams behave more absorbing at most of wavebands and temperatures. Alumina foams show an obviously forward predominance (asymmetry factor g > 0.4), and the fraction of forward scattering increases with increasing wavelength. Zirconia foams show a slight backward predominance (asymmetry factor g = -0.1) at short wavelengths, and a closely isotropic scattering was found at around wavelength λ = 7 μm. This study provides a feasible way to obtain the radiative properties of open-cell foams at high temperatures. Normal-normal transmittance and normal-hemispherical transmittance/reflectance of foams were measured at room temperature. The experimental results validate the numerical approach to obtaining radiative properties from analytical relations and bulk properties.

With the rapid development of the oil industry, oil-gas-water multiphase mixed transmission has become one of the most important transportation methods in the future. Based on the three-phase medium has different physical and chemical properties, making the mixture exists a mixed interface whose form and distribution are not sure in time and space. The oil-gas-water three-phase mixed transmission process in gathering transportation pipeline is studied by using the multiphase flow VOF model. And its flow pattern is identified. The bubbly flow and plug-like flow which often occurs in the engineering was simulated by studying the influence of initial gas rate on the flow pattern, and the influence of velocity on the bubble distribution in the bubbly flow is analyzed. The simulation results agree well with the theory, and could provide some theoretical guides for engineering applications.

For drawing up science and reasonable crude oil transportation craft, we should accurately forecast the change of soil temperature field around pipeline and oil temperature within pipeline. The soil temperature fields around the buried hot oil pipeline during starting and oil temperature within pipeline are numerically simulated through using finite elements method, find out how the soil temperature around pipeline distribute and oil temperature within pipeline change at different time. Analysis the calculation results show that the time of infusing oil after preheating should be in line with the requirement, and multiple factors obviously influence oil temperature change within pipeline, such as staring time, staring temperature etc. The reliable basis is provided for hot oil pipeline to operate economically and securely.