Multistage Membrane Process Research Articles

Multi-stage Membrane Processes for CO2 Capture from Cement Industry

Abstract Capture conditions for cement plant flue gas differ substantially from other industrial flue gases due to the high partial pressure of CO 2 , presenting an opportunity for polymeric membranes to compete with other capture technologies. In this work, two membrane processes are designed by applying a recently developed graphical methodology to identify promising membrane properties, number of stages and operating points for each stage. The net present values of cost and the CO 2 avoidance costs are compared with an MEA based capture unit when applied to a 0.7 MtCO 2 /year cement plant. The membrane designs are shown to have a significantly lower investment cost (32.6 M€ vs. 294 M€) and CO 2 avoidance cost (27 €/t vs 55 €/t) than the reference MEA based capture process. The investment cost for turbomachinery and the operating cost for electricity are also shown, in this particular case, to be more important than the membrane investment and replacement costs over the lifetime of the membrane capture plant. The present work underlines the importance of using a cost-based approach to balance the trade-offs in membrane process design.

Pilot-scale multistage membrane process for the separation of CO2 from LNG-fired flue gas

In this study, a multistage pilot-scale membrane plant was constructed and operated for the separation of CO2 from Liquefied Natural Gas (LNG)-fired boiler flue gas of 1000Nm3/day. The target purity and recovery of CO2 were 99vol.% and 90%, respectively. For this purpose, asymmetric polyethersulfone (PES) hollow fibers membranes has been developed in our previous work and has evaluated the effects of operating pressure and feed concentration of CO2 on separation performance. The operating and permeation data obtained were also analyzed in relation with the numerical simulation data using countercurrent flow model. Based on these results, in this study, four-staged membrane process including dehumidification process has been designed, installed, and operated to demonstrate the feasibility of multistage membrane systems for removing CO2 from flue gases. The operation results using this plant were compared to the numerical simulation results on multistage membrane process. The experimental results matched well with the numerical simulation data. The concentration and the recovery of CO2 in the permeate stream of final stage were ranged from 95–99vol.% and 70–95%, respectively, depending on the operating conditions. This study demonstrated the applicability of the membrane-based pilot plant for CO2 recovery from flue gas.

Modeling, Simulation, and Optimization of Postcombustion CO2 Capture for Variable Feed Concentration and Flow Rate. 1. Chemical Absorption and Membrane Processes

Studies on leading technologies for industrial CO2 capture are performed. Each technology includes flue gas dehydration, capture of at least 90% of CO2 from the feed, and compression to almost pure CO2 for sequestration at 150 bar. This paper presents the modeling, simulation, optimization, and energy integration of a monoethanolamine (MEA)-based chemical absorption process and a multistage membrane process over a range of feed compositions (1–70% CO2, 5.5–15% H2O, 5.5% O2, and the balance N2) and flow rates (0.1, 1, 5, and 10 kmol/s). A superstructure of process alternatives is developed to select the optimum dehydration strategy for the feed to each process. A rigorous simulation-based optimization model is proposed to determine the minimum annualized cost of the MEA-absorption process. The MEA-absorption process is energy integrated through heat exchanger network optimization. A novel mathematical model is developed for the optimization of multistage and multicomponent separation of CO2 using membranes...

Fouling minimised reclamation of secondary effluents with reverse osmosis (ReSeRO)

Abstract A group of researchers from Israel and Germany investigates fouling minimized reclamation of secondary effluent of municipal waste waters for unrestricted irrigation. Countries with increasing water scarcity including Israel are forced to use secondary or tertiary effluents for irrigation. The quality of the effluents can be increased to the levels of drinking water with multistage membrane process where low pressure membranes, mostly ultrafiltration (UF) are used as a pretreatment to reverse osmosis (RO). The minimisation of the organic and biofouling on UF and RO membranes is achieved by different pretreatments including biofiltration, coagulation and adsorption on powdered activated carbon. The pretreatment options are considered separately and in various combinations. The reduced fouling will also be achieved by modification of the membrane surface by the manufacturer. This study incorporates field and lab experiments, the latter are performed for a better understanding of biofouling-induced ...

Energy saving in sugar manufacturing through the integration of environmental friendly new membrane processes for thin juice pre-concentration

In the present work energy savings in clarified thin sugar juice pre-heating and concentration are presented by integrating a new pressure-driven multistage membrane process with multiple-effect evaporator (MEE). The thin sugar juice is concentrated from 15 w% to 50 w% with membrane and from 50 w% to 70 w% in MEE. The new process will not only reduce the energy consumption of thin juice concentration process significantly but will also reduce the requirements of energy and heat transfer area of heat exchangers for pre-heating the thin juice before evaporation by 70%. The existing sugar factories may increase the capacity of their evaporation station through the integration of the new membrane process while new factories to be built will have a smaller sized evaporation station with more energy efficiency and environmentally friendly process performance and with a significantly smaller carbon footprint.

Integrated design of a gas separation system for the upgrade of crude SNG with membranes

This paper investigates different design strategies and process layouts for upgrading crude synthetic natural gas (SNG) produced from lignocellulosic biomass to grid quality. The design problem is outlined by studying the involved key aspects with respect to the crude composition, purity requirements and process integration. A discussion of candidate technology identifies multistage membrane processes as a promising option, for which a multicomponent thermo-economic design model is coupled to a process model for SNG production. In a design study using multi-objective optimisation, the most promising membrane configurations are identified and optimised with respect to cost and efficiency. Comparing design strategies that consider different levels of process integration, it is shown that coupling the reactive and separation sections improves the process design. If process integration is not considered, the separation system is oversized by up to 60% and its investment cost is up to 46% too high. In the last part of the paper, the by-production of biogenic CO 2 at sufficient purity for storage is investigated, which would turn the process into a CO 2-sink for the atmosphere. The cost of captured CO 2 is assessed between 15 and 40 €/ton, which makes it potentially more advantageous than the capture at a fossil fuel power plant.

Carotenoids from red palm methyl esters by nanofiltration

AbstractPalm oil contains high concentrations of carotenoids and tocopherols that can be recovered by first converting them to methyl esters and then applying membrane technology to separate the carotenoids from the methyl esters. Several solvent‐stable nanofiltration membranes were investigated for this application. Flux with a model red palm methyl ester solution ranged from 0.5 to 10 Lm−2h−1, and rejection of β‐carotene was 60–80% at a transmembrane pressure of 2.76 MPa and 40°C. A multistage membrane process was designed for continuous production of palm carotene concentrate and decolorized methyl esters. With a feed rate of 10 tons per hour of red palm methyl esters containing 0.5 gL−1 β‐carotene, the process could produce 3611 L·h−1 of carotene concentrate containing 1.19 gL−1 carotene and 7500 Lh−1 of decolorized methyl esters containing less than 0.1 gL−1 β‐carotene. The economics of this process is promising.

Membrane-based separation scheme for processing sweeteners from stevia leaves

In existing processes, extraction and refining of glycoside based sweeteners from stevia leaves involves many process steps including extraction by organic solvents. The purpose of the present study was to develop a process of extraction and refining of sweeteners with reduced number of unit operations and minimization and/or elimination of chemical usage including organic solvents. It was found that water was very effective for extracting glycosides at selected pH and temperatures. It was also shown that a multi-stage membrane process was successfully able to concentrate the glycoside sweeteners. Based on the preliminary results, it appears that bitter-tasting components were washed out from the sweetener concentrate in the nanofiltration process. This work also has demonstrated that a membrane-based separation process for refining glycoside-based sweeteners could be viable and needs to be investigated further.

Multi-stage membrane process for gas separation

Multi-stage membrane process for gas separation

Sulphur dioxide control by reactive photografted membranes immobilizing high surface area calcium oxide

The effects of temperature (313–423 K), of feed SO 2 concentration (985–2200 ppm (v/v)), of pore size (0.04–1.9 μm) and of surface area (11–39 m 2 g −1) of CaO sorbent on the reactivity of composite membranes, immobilizing 30 wt.% of sorbent in an epoxy-diacrylate resin matrix photografted onto cellulose, towards SO 2, have been studied at constant flow rate (1.85 cm min −1) and pressure (1 bar gauge). Moisture in the test gas was kept constant, by saturation with water at 343 K. With high surface area CaO and at the dew point temperature the % of SO 2 captured was always greater than 50%, approaching 95–98 % at 313 K where capillary condensation of water vapour occurred. In the lower temperature range, the presence of liquid water in the membrane pores slackens gas diffusion, enhances SO 2 solubility and consequently favours reactivity. The dependency of sorption rate on temperature and on pore size allows us to find experimental conditions, in which to operate with a sorption efficiency significantly lower than unity, but with an equally satisfactory overall yield, in a multistage membrane process, provided high surface area sorbents are used, and membranes immobilizing these sorbents are manufactured by a technique, such as photografting, able to maintain this surface area almost entirely active.