Qin Y.,Chembrane Research and Engineering Inc. |
Liu R.,Tianjin University |
Li X.,Tianjin University |
Liu L.,Chembrane Engineering and Technology Inc. |
Zhang Y.,Chembrane Engineering and Technology Inc.
AIChE 2012 - 2012 AIChE Annual Meeting, Conference Proceedings | Year: 2012
It is well known that hydrochloric acid (HCl) is usually used as pickle liquor to remove surface oxide in a steel production industry. When pickling cannot be accomplished effectively and the quality of the treated metal surface deteriorates, the pickle liquor is discharged from the pickling tank, and the pickling tank is replenished with fresh acid solution. According to the data provided by the World Steel Association in 2011, the total world crude steel production was 1,490.1 million tonnes. And about 60 kg of spent pickle liquor was generated with the production of each ton of steel, and thus annual emission of spent pickle liquor was up to several million tons. As an example, 1000 ton of pickle liquor is being produced daily in a steel plant in north China, which contains 7% HCl and 15% FeCl2. The spent pickle liquor usually contains 2-8 wt% hydrochloric acid and is considered a hazardous waste. The spent pickle liquor from steel processes is usually neutralized with lime and disposed in a landfill, which results into the following problem: high-salinity wastewater and sludge volume, the remaining salt residue processing difficulties, and most importantly, the acid unrecoverable. Therefore, there is an urgent need to recover and enrich hydrochloric acid to achieve economical and ecological benefits. Since the 1960s, hydrochloric spent pickling liquor is often treated in a hydrochloric acid regeneration system such as ion-retardation, diffusion dialysis and electro-dialysis, which recovers some of the hydrochloric acid and ferric oxide. Nevertheless, these regeneration processes produce lots of dilute hydrochloric acid solution. Thus, there still needs a novel and efficient technology to concentrate the recovered dilute HCl solution for further use. In the last few years, numerous studies have been performed to test the application of membrane distillation for concentrating dilute HCl solution. However, the high thermal energy consumption of the traditional MD process is one of the biggest barriers in its industrialization. In the present study, multiple-effect membrane distillation (MEMD) based on AGMD module with function of internal heat recovery has been developed. This kind of MEMD process combines the advantages of MD process and conventional MSF process, avoids the disadvantages of MSF such as evacuation operation, and can provide a high PR value. The effects of feed-in concentration, cold feed-in temperature (Tc), hot feed-in temperature (Th) and feed-in volumetric flow rate (F) on the performance of MEMD process were studied. The permeation flux (N) and energy efficiency, performance ratio (PR), and the average selectivity of water over HCl (βavg) are the most important indicators for module performance evaluation. N indicates the productivity of this device; PR (performance ratio) is usually used to determine the thermal efficiency of evaporation-based process, which is defined as the amount of latent heat needed for evaporation of the produced water and the amount of heat provided to the system from an external energy source; βavg is represents the measure of the preferential transport of water. The results showed that MEMD process could be used successfully for concentrating dilute HCl solution with the advantage of energy saving. The experimental data indicated that all N, PR and βavg decreased with the increase of feed concentration. When the feed concentration was below 12 wt%, PR could achieve 6.0∼9.6, and βavg was about 10~190. As the concentration of HCl achieved 18 wt%, the values of PR and βavg were still about 4.4 and 2.3, respectively. However, βavg sharply decreased to a value around 1.0 when feed was further concentrated. It is also found that there exists trade-off phenomenon between N, PR and βavg under experimental ranges, that is, the maximum N will be obtained with high temperature Th, low temperature Tc and high flow rate F while the maximum PR is obtained with high temperatures Th and Tc, as well as low flow rate F. the lowest βavg will be obtained with low temperature Th, low temperature Tc and low flow rate F. During an operational stability test lasting for 30 days, the performance of MEMD modules was kept in good condition.
He J.,Tianjin University |
Shan P.,Tianjin University |
Zhang L.,Tianjin University |
Qin Y.,Tianjin University |
Qin Y.,Chembrane Research and Engineering Inc.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2012
Separation of dimethylamine from the aqueous solution was carried out by using a supported-gas-membrane absorption method with the hollow-fiber membrane modules. In this paper, three experimental conditions affecting mass transfer were investigated trough an orthogonal experiment, and the effects of two factors, including overall mass transfer coefficient and the rate of dimethylamine removal, were evaluated. It can be found that the two evaluation factors increases with increasing the feed temperature, whereas with increasing the feed velocity, the overall mass transfer coefficient increases and the rate of dimethylamine removal decreases. The effect of feed-in concentration of dimethylamine on the overall mass transfer coefficient and the rate of removal are not significant. The best experimental conditions were obtained by single-factor experiments with a feed temperature of 45 °C, a feed velocity of 0.08 m·s -1 and a feed-in concentration of 3000×10 -6. These results demonstrate that among the three experimental conditions, feed temperature is the most influential factor on the separation process, followed by the feed velocity. The feed-in concentration affected the system negligibly. Through a stability test, it can be seen that the properties of the membrane modules still remain very high after 550 hours run over.
Li X.,Tianjin University |
Qin Y.,Tianjin University |
Liu R.,Tianjin University |
Zhang Y.,Chembrane Research and Engineering Inc. |
Yao K.,Tianjin University
Desalination | Year: 2012
Multiple-effect membrane distillation (MEMD) process, by using a hollow fiber-based AGMD module and an external heat exchanger, was studied to concentrate dilute sulfuric acid solution. Latent heat of distillate was in-situ recovered by directly heating the cold feed within the AGMD module of special configuration. Permeation flux (Jw) and performance ratio (PR) parameters were used to characterize the operation performance of MEMD process. PR value obtained in the MEMD process was much higher than that obtained in traditional and the other modified membrane distillation process. The effects of heated feed-in temperature, cold feed-in temperature, feed-in flow rate and feed-in concentration on the MEMD performance were experimentally investigated. The dilute sulfuric acid in 2wt.% could be concentrated up to about 40wt.% by using MEMD process. The maximum value of PR and Jw could reach 11.5 and 5.3L/m2h, respectively. When the feed concentration was up to 20wt.%, the value of PR and Jw could still be 4.9 and 1.9L/m2h, respectively. In a long-term stability test lasting for >30days, the electrical conductivity of the distillate was always less than 150μs/cm, which demonstrated that the performance of MEMD modules was kept in good condition. © 2012 Elsevier B.V.
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 749.25K | Year: 2005
75772B Most coal-based power plants use pulverized coal boilers to generate superheated steam for turbine applications, accounting for over 50 percent of U.S. electricity generation. The flue gas stream from these plants contains CO2, along with N2 and other minor components such as SO2 and NOx. Although some commercial technologies are available to separate or capture the CO2 from the flue gas, in order to reduce the buildup of greenhouse gases in the atmosphere, these processes are both capital intensive and high in operating costs. This project will develop a membrane-based hybrid process for capturing and enriching the CO2 from the warm flue gas streams emitted from pulverized-coal-fired power plants. When retrofitted on conventional air-based, fossil-fuel-fired power plants or integrated into new power-generation facilities, the process will capture more than 90% of the CO2, and compressed CO2 with greater than 99 vol% purity will be obtained. In Phase I, the membrane-based hybrid system was developed and tested on a simulated flue gas containing 10 to 15% CO2. A product stream containing 99.3-99.6 vol% CO2 was produced with a recovery effeciency of >90%. Parametric optimization and techno-economic analysis were performed over a range of temperatures, CO2 partial pressures, and SO2 contents in the flue gas. In Phase II, the membrane hybrid sytem will be further optimized to provide higher CO2 capture efficiency and higher CO2 purity. Long-term experiments will be performed to test the operational stability of the membrane system when used to treat simulated flue gas containing both SOx and NOx. Finally, a prototype system will be tested in a pilot plant. Commercial Applications And Other Benefits as described by the applicant. The membrane-based hybrid process should provide superior performance compared to the conventional processes for CO2 separation/capture (i.e., amine-based absorption/desorption, membrane gas absorption, and conventional membrane gas permeation processes). The cost of capturing (separating, compressing, and liquifying) 90% CO2 from a flue gas stream containing 15% CO2 would be 1.275 - 1.80 cent/kWh (or 13.5 ¿ 20 dollars/ton CO2 avoided).
Agency: National Science Foundation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.99K | Year: 2003
This Small Business Innovation Research (SBIR) Phase I project will develop a gas permeation process and membrane to separate olefin/paraffin mixtures in which a multilayer multifunctional membrane configuration ensures high selectivity, high olefin productivity, good mechanical stability, excellent impurity tolerability, and long-term operational reliability. Hollow fiber membrane modules will be developed to enhance the olefin permeance 2~10-fold compared to those by conventional polymer facilitated transport membranes in addition to much enhanced olefin/paraffin selectivity. This membrane system has long-term stability and reliability to dry feed containing trace amounts of H2, C2H2, and/or H2S that cannot be treated by traditional membrane processes. Compared to the other membrane processes, this process is more promising and cost-effective. If successfully developed, it could be applied very widely to olefin/paraffin separations.