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Improving the energy-saving efficiency of flue gas deep waste heat and reducing the emission of carbon dioxide and other pollutants have been two issues that need to be paid attention to in petrochemical heating furnaces. A hydrogen production reformer with high energy consumption and high carbon emissions in the petroleum refining process affects the thermal and productive efficiency of the hydrogen production, amounts of heat from flue gas are wasted with the exhausted corrosive gas of the reformer, and latent heat is not recovered. To recover the sensible and latent heat from the exhausted gas, a new anti-corrosion, high-efficiency, and low-pressure-drop flue gas condensing heat exchanger (FGCHE) with low consumption and pressure drop was developed. The energy-saving performance was evaluated through on-site measurements and theoretical analysis. The results show that the exhausted gas temperature was reduced from 161.3~175.9 °C to 33.9~38.9 °C after using the new FGCHE to recover waste heat. The energy-saving efficiency and the utilization ratio of flue gas waste heat were 12~16.1% and 74~81.9%, respectively. The latent heat accounted for 41.3~48.1% of the total recovered heat. The exergy efficiency and the total thermal efficiency of the reformer reached 73~86.8% and 95.2~96.6%, respectively. The condensation in the flue gas reduced pollutant emissions (SO2 and NOx). This paper provides a practical application reference for the technology development of waste heat recovery and the application of an FGCHE for petrochemical heating furnaces. [ABSTRACT FROM AUTHOR]

The liquid film thickness seriously affects the distribution of temperature, velocity, and components near the interface for steam condensation in the presence of small concentration noncondensable gas. The liquid film thickness for H2O/CO2 forced convection condensation separation on vertical plate has not been studied numerically. Thus, volume of fluid model and a phase change model were used to study steam condensation in the presence of noncondensable gases. The calculations studied the effects of velocity, surface subcooling, and noncondensable gas mole fraction on the heat transfer for H2O/air or H2O/CO2 mixtures. The results show that the predicted heat transfer coefficients agree well with previous experimental data. The gas and liquid film thicknesses controlling the condensation heat transfer in the presence of a noncondensable gas become thicker as the mixture flows along the cooled wall. The condensate mass flow rate and the heat transfer coefficient are both seriously reduced by the noncondensable gas. The condensate heat transfer in the presence of noncondensable gases is mainly determined by the diffusion coefficient and the thermal conductivities of the components in the gas film layer. [ABSTRACT FROM AUTHOR]

Adsorption separation technology has great potential to separate H2O/CO2 mixture with 1–5% H2O to achieve high CO2 purity for industrial applications. However, there are few studies analyzing the concentration and velocity fields in an adsorption column and the characteristics of H2O/CO2 adsorption separation. A heat and mass transfer model of H2O/CO2 adsorption on aluminum activated F-200 was developed and validated experimentally to predict the breakthrough curves and the H2O/CO2 distributions in the gas and solid phases. The effects of mixture inlet velocity, inlet temperature, steam mole fraction and total pressure on the separation performance have been investigated numerically. As velocity increases, the breakthrough and equilibrium times decrease. The peak temperature gradually increases with increasing H2O concentration, temperature and pressure. Along the height of the adsorption column, the adsorption ratio, the ratio of the amount adsorbed to the equilibrium amount adsorbed first decreases and then increases with increasing H2O mole fraction, but first increases and then decreases with increasing pressure. The heat and mass transfer characteristics of the H2O/CO2 adsorption separation can provide a basis for high purity CO2 separation. [ABSTRACT FROM AUTHOR]

It is a coupling solution for optimizing the materials with good thermal conductivity and anti-corrosive modified coating of flue-gas condensation heat exchangers. The paper experimentally studied the condensation heat transfer between the wet air and 3-D finned-tube heat exchanger surface in three different ways, i.e. non-coating, Ni-Cu-P organic pure-coating, and Ni-Cu-P chemical organic composite coating. Impacts of mass flow rate, moisture content, temperature of exhaust flue gas, and cooling water on the condensation heat transfer performance were investigated. The results showed that the heat transfer coefficient of the heat exchanger surface with a pure-coating layer achieves 3.1–7.4% higher compared to that with the composite coating. The pure-coating surface is inferior to the non-coating surface. The heat transfer coefficient of the copper-based heat exchanger achieves 30.1–47% higher compared to the steel-based surface. The condensate pH of modified surfaces heat exchangers is ranged from 3.08–7.17. Furthermore, the nondimensional correlations governing the flue-gas convection condensation heat transfer for different coating surfaces were established and validated with the experimental data. The validation indicates that the theoretical results are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

This paper presents a low-cost approach to power factor correction (PFC) of single-phase diode rectifiers using a series active filter. Comparing with the traditional PFC, the proposed PFC has lower requirements of power device ratings, which leads to lower cost, higher efficiency, and lower electromagnetic interference. It also can eliminate the bulky inductor needed in the traditional PFC. The topology, operation principle, and application issues of the proposed PFC are analyzed in this paper. The control strategy is discussed in detail and simulation results are provided. A 1-kW prototype is built up and the experimental results are presented to verify the analysis. Index Terms--Adjustable-speed drive, heating, ventilating, and air conditioning (HVAC), power factor correction (PFC), series active filter.