Techno-economic assessment of boiler feed water production by membrane distillation with reuse of thermal waste energy from cooling water

Redesign of the milk powder production chain: assessment of innovative technologies

“…For milk concentration, besides heating also cooling of the recirculation loop is necessary in order to maintain the driving force. The energy required for a single stage system is 2.6 MJ for heating and 2.5 MJ per kilogram water removed for cooling, which is much higher compared to previously reported values for MD on desalination González et al, 2017;Koschikowski et al, 2009;Kuipers et al, 2014;Mar Camacho et al, 2013) and traditional multi-stage evaporator systems. Cooling is not required for desalination, as the permeate is the aimed product, and not the concentrate which is aimed for food products like milk.…”

“…Downside is the lower fluxes due to increased vapor transport resistance. Fluxes up to 75 L/m2.h for direct contact membrane distillation (Schofield, Fane, Fell, & Macoun, 1990), and ranging from 1 to 4.5 L/m2.h for air-gap membrane distillation are reported (Duong, Duke, Gray, Cooper, & Nghiem, 2016;Kuipers et al, 2014). Concentration polarisation, which occurs in pressure driven membrane filtration, is not limiting and therefore high solid contents can be realised with membrane distillation (Tijing, Choi, Lee, Kim, & Shon, 2014).…”

“…Dow et al showed how integration of a direct contact membrane module in a power station for water production could run on the available waste heat (40°C), with an average energy consumption of 1500 kWh/m 3 (5.4 MJ/kg water removal) . Several pilot modules with internal heat recovery (air-gap membrane distillation) have been tested for desalination, resulting in energy consumptions ranging from 100 to 350 kWh/m 3 (0.4 -1.3 MJ/kg water removal) Guillén-Gosálbez, Caballero, & Jiménez, 2008;Koschikowski et al, 2009;Kuipers et al, 2014;Mar Camacho et al, 2013). Depending on the availability of waste heat and the desired fluxes either direct contact or air-gap membrane distillation could be favourable.…”

“…Both systems operate at low temperatures, around 60°C, which makes MD processes interesting for heat sensitive products like fruit juices and dairy products. The thermal energy consumption is, however high compared to RO and modern multi-stage evaporators, with an energy consumption of 400 -1300 kJ per kg water removed (Duong, Cooper, Nelemans, Cath, & Nghiem, 2016;González, Amigo, & Suárez, 2017;Koschikowski et al, 2009;Kuipers et al, 2014;Mar Camacho et al, 2013;. The advantage of MD is in the low operating temperatures, which allow the usage of low-quality heat, for example waste heat of other processes.…”

“…The advantage of MD is in the low operating temperatures, which allow the usage of low-quality heat, for example waste heat of other processes. Several studies suggested and investigated the usage of waste heat for operating the MD process Hausmann, Sanciolo, Vasiljevic, Weeks, & Duke, 2012;Kuipers et al, 2014). In presence of abundant waste heat with temperatures of at least 40 -70°C, MD might be an interesting alternative for traditional concentration methods like multi-stage evaporation.…”