Simultaneous heat and water recovery from flue gas by membrane condensation: Experimental investigation

Abstract

Simultaneous heat and water recovery from flue gas by membrane condensation: Experimental investigation, Applied Thermal Engineering (2016), doi: http://dx.doi.org/10.1016/j.applthermaleng. 2016.11.101 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1Simultaneous heat and water recovery from flue gas by membrane A tubular ceramic membrane is investigated as the condenser for simultaneous heat and water 2 recovery from flue gas. The effects of the operational parameters, such as fluid (gas and water) 3 flow rates, temperatures of flue gas and coolant water, and flue gas humidity on the process 4 performance in terms of mass and heat transfer across the membrane are studied. Particularly, 5 the overall heat transfer coefficient is also evaluated. As the gas flow rate increases, water and 6 heat transfer efficiencies and recoveries decline due to the reduced residence time. Increasing 7 the water flow rate or lowing the coolant temperature can effectively improve mass and heat 8 transfer efficiencies and recoveries. Increasing the temperature of the inlet gas can enhance 9 water and heat fluxes and recoveries, but does not improve the overall heat transfer efficiency. 10The rise in flue gas humidity can dramatically improve water and heat transfer rates and the 11 overall heat transfer coefficient, but has little effect on water and heat recoveries. These 12 results offer a general guideline in optimising the operational parameters in low-grade heat 13 recovery with membrane heat exchangers, and it may greatly advance the development of 14 membrane condensation technology for practical low-grade heat recovery.

Experimental Study on Water Recovery from Flue Gas Using Macroporous Ceramic Membrane

“…A part of water vapor is not condensed and then discharges out of the membrane module. The gas humidity ratio decreased with the increase in gas flow rate [30]. The moisture content of the gas did not increase proportionally with the increase of gas flow rate; as a result, water flux decreased slightly, which was the main factor leading to the water recovery flux variation showing an opposite trend to that of this study.…”

“…The pore sizes of the ceramic membranes and experimental conditions in each study were different. A nanoporous ceramic membrane tube, which was an inner coating membrane, was used [4,21,30]. Gao et al [35] used the same membrane tube as this article, which was an outer coating membrane with an average pore size of 1 µm.…”

“…In order to explore the application value of economical TMC in engineering and reduce the equipment investment cost of flue gas moisture recovery, in this paper, a single-membrane tube with a pore size of 1 µm was used for the experimental study of extracting moisture and waste heat from the exhaust gas. An inner-coating membrane tube was used, i.e., the gas flowed inside the pipe [4,21,22,30]. On the other hand, an outer-coating membrane tube was used here, whereby the flow pattern did change, and water coolant in place of gas flowed inside the tube.…”

Retracted: Techno-economic analysis of a novel hot-air recirculation process for exhaust heat recovery from a 600-MW hard coal-fired boiler

“…Especially when the flue gas is cooled to a temperature below its water dew point, the tubular heat exchanger for heat recovery must be made of expensive stainless steel, 11 which makes the benefit from the recovery project very little. As a countermeasure to acid corrosion, the fluorine plastic heat exchanger, 12 ceramic membrane condenser, [13][14][15] and open LiBr solution absorption system 16 were advanced for trial in laboratory or pilot scale. However, these technologies still need to be further developed before being applied in a large-scale thermal power plant.…”

Investigation of the Concepts to Increase the Dew Point Temperature for Thermal Energy Recovery from Flue Gas, Using Aspen®

“…During the heat exchange with the cooling liquid, the flue gas temperature is reduced below the dew point, so that the water vapour is condensed and the release of the latent and sensible heat occurs. Porous and non-porous gas separation membranes have been actively developed for the simultaneous heat and water recovery from the flue gas [7,13]. The growing interest for the thermal energy recovery application is connected to the Organic Rankine Cycle (ORC) technology for generation of electricity and absorption refrigerator (AR) technology for driving cooling processes [5,[14][15][16].…”