An experimental study on vapor condensation of wet flue gas in a plastic heat exchanger

Experimental Study on a Ceramic Membrane Condenser with Air Medium for Water and Waste Heat Recovery from Flue Gas

Ceramic membrane condensers that are used for water and waste heat recovery from flue gas have the dual effects of saving water resources and improving energy efficiency. However, most ceramic membrane condensers use water as the cooling medium, which can obtain a higher water recovery flux, but the waste heat temperature is lower, which is difficult to use. This paper proposes to use the secondary boiler air as the cooling medium, build a ceramic membrane condenser with negative pressure air to recover water and waste heat from the flue gas, and analyze the transfer characteristics of flue gas water and waste heat in the membrane condenser. Based on the experimental results, it is technically feasible for the ceramic membrane condenser to use negative pressure air as the cooling medium. The flue gas temperature has the most obvious influence on the water and heat transfer characteristics. The waste heat recovery is dominated by latent heat of water vapor, accounting for 80% or above. The negative pressure air outlet temperature of the ceramic membrane condenser can reach 50.5 °C, and it is in a supersaturated state. The research content of this article provides a new idea for the water and waste heat recovery from flue gas.

Influence of nitrogen/phosphorus-doped carbon dots on polyamide thin film membranes for water vapor/N2 mixture gas separation

Nanoparticles have been attracting attention because they can significantly improve the performance of membranes when added in small amounts. In this study, the effect of polyamide membranes incorporating hydrophilic nitrogen/phosphorus-doped carbon dots (NP-CDs) to enhance water vapor/N₂ separation has been investigated. NP-CD nanoparticles with many hydrophilic functional groups are synthesized from chitosan by a one-pot green method and introduced to the surface of the polysulfone (PSf) substrates by interfacial polymerization reaction. The mean particle diameter of NP-CDs, estimated from transmission electron microscopy images, is 2.6 nm. By adding NP-CDs (0–1.5 wt%) to the polyamide layer, the contact angles of the membranes dramatically decreased from 65° (PSf) to <9° (thin film nanocomposite (TFN)), which means that the TFN membranes become significantly hydrophilic. From the water vapor separation results, the addition of NP-CDs in the polyamide layer improves the water vapor permeance from 1511 (thin film composite (TFC) without nanoparticles) to 2448 GPU (TFN with 1.0 wt% NP-CD loading, CD-TFN(1.0)) and the water vapor/N₂ selectivity from 73 (TFC) to 854 (CD-TFN(1.0)). To our knowledge, this is the first study of highly functionalized NP-CD-incorporated polyamide membranes to enhance water vapor separation.

Nanoparticles have been attracting attention because they can significantly improve the performance of membranes when added in small amounts.

Highly selective thin film composite hollow fiber membranes for mixed vapor/gas separation

In the present study, thin film composite membranes have been prepared using an interfacial polymerization method.