The use of reverse osmosis (RO) in food and beverage plants
In a plant food or drink, reverse osmosis (RO) is often used to sanitary water pretreatment plant and the boiler water. Recently RO increasingly used in food processing and beverages, for example, concentrated juice.
End use of the permeate (or waste water) tend to dictate the design of reverse osmosis (RO) system. Since most of the food vessel generally require a low hardness and suspended solids from the water supply, RO systems, this application is always followed by a kind of more thorough cleaning, so as to soften (if the low pressure boilers are ), or demineralization (if it has a higher pressure boilers are present). Reverse osmosis systems alone is not able to provide boiler feed water quality requirements, even at low pressure boilers.
If the reverse osmosis (RO), water (or pass or reject) is used for different applications in feed water, purification of the liquid is usually required.
If a reverse osmosis system is directly involved in food processing and beverages, RO performances (permeate or reject the quality and flow) must be kept in line with expectations. If you have problems with the RO equipment, such as fouling, so that the quality of plant products or quantity is directly affected. This can have a drastic effect on plant profitability.
To understand how reverse osmosis
To understand how RO should take into account the physical and osmotic pressure of semi-permeable membranes.
semipermeable membrane allows some molecules to travel through. If a concentrated aqueous solution on the opposite side there are semi-permeable membrane, the molecules of pure water spontaneously diffused the weaker side of the membrane more concentrated. This is called osmosis.
As the water molecules flow through the membrane, increases the amount of water on the side of the membrane concentrate and pressure, called pressure head. Once the increased pressure load to a level that the water flow can not occur through the membrane, the system is in balance. The pressure at this stage is called osmotic pressure. Is proportional to the concentration of dissolved solids in the more concentrated solution.
According to Van't Hoff's equation for calculating osmotic pressure
(Symbol P) ...
PV = nRT = (g / m) or RT
P = (g / m) RT / V, where
R = universal gas constant, 0.0821 atm • L / (mol • K)
T = absolute temperature K (Kelvin)
g = weight of the solute in grams
V = volume of solution, Liter
m = molecular weight of the solute, if nonionic
n = moles
P = osmotic pressure, atmospheres
Using this equation, and its application to an aqueous solution of 1,000 mg / L. dissolution of ionic solids such as CaCO3, we osmotic pressure of 7.2 psi [50 kPa] at 77 ° F.
In general, the average osmotic pressure of about 1 psi [6.9 kPa] per 100 mg / L. dissolved solids.
To apply pressure to the concentrated side of the membrane, which can reverse this process. molecules of pure water (and dissolved gas molecules) may be forced to take sides to dilute the concentrate side.
This is the whole or a process of reverse osmosis "RO" in a nutshell. Water purification occurs when water molecules are concentrated flows through semi-permeable membrane to dilute side.
To overcome the osmotic pressure, forcing water molecules to a stream, you must apply pressure. Net driving pressure to be defined as follows:
NDP = supply pressure permeate + OP (usually negligible) - permeate pressure - flow UP
OP = osmotic pressure
The flow through a reverse osmosis membrane is proportional to the NDP.
For reasonable rates of permeate flux and to minimize membrane fouling, pressure must be applied very broadly that the calculated P. Usually about 200 to 450 psi [1.4 to 3.2 MPa]. This high pressure requires specific design considerations of RO trains, and the elements.
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As a leader in the development of reverse osmosis (RO) systems, Layne Christensen Company has the technical expertise to design and construct a reverse osmosis system for all your water needs.
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