Industrial Reverse Osmosis - Designing Reverse Osmosis Equipment in Power Generation Facilities

In a power plant, industrial Reverse Osmosis equipment (RO) is used almost exclusively in the boiler water pre-treatment area. Since most power boilers tend to operate at elevated pressure (>700 psig [4.8 MPa]), boiler feed water quality is very stringent. As a result, industrial Reverse Osmosis Equipment in this application is invariably followed by some type of demineralization (demin) polishing equipment, designed to reduce feed water dissolved solids, especially silica, to very low levels. Industrial Reverse Osmosis equipment, by itself, is incapable of providing the boiler feed water quality demanded by higher pressure power boilers.

osmosis water filter

Because the polishing demineralization equipment in a power generation facility will be sized upon the expected industrial Reverse Osmosis equipment performance (permeate water quality and quantity), any problems with the Reverse Osmosis equipment operation can have drastic effects on the demin performance. Poor demin performance can cause costs to increase sharply, through increased regenerations and acid/caustic usage.

OSMOSIS

 Further downstream, the impact of poor industrial Reverse Osmosis equipment performance on the power generation boilers can be severe, ultimately leading to plant de-rating, and even boiler and turbine damage.

Understanding Reverse Osmosis Design for a Power Generation Facility There are four main components of an industrial Reverse Osmosis equipment system: Element, Array (Train), Stage, and Pass.

The industrial Reverse Osmosis Element is the building block of any RO equipment system. It is the individual component, where the RO process occurs.

There are four main designs for the elements:

Spiral Wound - Most common design for water purification Hollow Fiber - Very large membrane surface areas are possible in this design. Used in seawater desalination Large Tube - Similar to a shell-and tube heat exchange in appearance and design. Used in special wastewater treatment and food processing applications Flat Plate - Similar to a plate-and frame heat exchanger. Used in food processing applicationsRegardless of the element design, high pressure and flow is needed to force pure water through the RO membrane to become permeate. Because of the high pressures needed, each element must be designed so that the internal structures can withstand a feedwater pressure of several hundred psig.

The number of elements needed will be determined by the amount of the final product needed daily.

 The industrial RO equipment Array is simply the way in which the elements are grouped together, in series or parallel.

Industrial Reverse Osmosis - Designing Reverse Osmosis Equipment in Power Generation Facilities

OSMOSIS

Industrial Brackish Water Reverse Osmosis Systems

b>Introduction
In December 2008, Pure Aqua successfully supplied a skid-mounted Industrial Brackish Water Reverse Osmosis (BWRO) system to produce 50m3/hr product at 77°F using (42) 8"x40" FILMTEC LE-440i membrane elements, (6) FRP pressure vessels 7 elements per each vessel, SS multistage pump, PLC based controls and a digital conductivity and ORP read out, 380V/3ph/50Hz.

osmosis jones dvd

Systems and Process
Feed water to the system is from bore-well with raw water TDS of about 2451 PPM. The system design was based on high rejection TFC spiral wound membranes. The Brackish Water Reverse Osmosis system was selected from our RO-500 Series, model number BW-320K-6780-3. The Brackish Water Reverse Osmosis (BWRO) unit consists of 5-micron cartridge filters to reduce feed water Silt Density Index (SDI) and to limit the SS to 5-micron size and advanced PLC control panel with touch panel screen. Pre-treatment and post-treatment includes the following:

OSMOSIS

*Antiscalant dosing to minimize the precipitation of sparingly soluble sulfate
*Multimedia filters to remove suspended solids and reduce turbidity
*Carbon filters
*Cartridge filter with 0.2 micron cartridges
*Filter feed and backwash pumps
*Post UV system

Plant Design Summary
*Application: Bottling
*Total Plant Design Capacity: 1200 m3/day
*Product TDS: General Use = less than 240PPM
*Chemical Treatments: Antiscalant
*Feed TDS: 2451 PPM
*Maximum Pressure: 300psi
*System Recovery: 65%
*Feed SDI: Less than 3

Performance
From a feed TDS of about 2451 PPM at a temperature range of 19°C and 28°C, the BWRO skid produces 50 m3/hour of drinking water with TDS less than 240 PPM matching WHO standard for drinking water.

==> Dubai Sports City
Industrial Reverse Osmosis Waste and Processed Water

Introduction
In the Middle East, fresh water is becoming more and more difficult and expensive to obtain. As a result countries are investing in alternatives in water pufication such as reverse osmosis and desalination. In May 2007, Pure Aqua successfully supplied a water treatment package consisting of a Reverse Osmosis System to produce 200 gpm of product from 250 gpm feed, antiscalant chemical dosing, prechlorination chemical dosing, acid injection dosing, and dechlorination dosing systems.

Systems and Process
Feed water to the system is processed water with raw water TDS of about 1,500 PPM. The system design was based on high rejection TFC spiral wound low fouling membranes. The Reverse Osmosis system was selected from our RO-500 Series, model number BW-360K-8680-3. It produces 200 gpm of drinking water with TDS less than 100 mg/L. The Reverse Osmosis unit consists of 5-micron cartridge filters to reduce feed water Silt Density Index (SDI) and to limit the SS to 5-micron size. TFC spiral wound membranes have a recovery rate of 80% with an advanced microprocessor control panel and cleaning system.

Performance
From a feed TDS of about 1,500 mg/L at temperature range of 27°C, the system produces 200gpm of high quality water at less than 100 ppm. The water produced will be used in the water park area of the Sports Center in boating areas, pools and water slides.

==> Salam, Dubai UAE
Industrial Brackish Water Reverse Osmosis System

Introduction
The Industrial Brackish Water Reverse Osmosis Unit was manufactured and supplied by Pure Aqua in January 2008 for a major water treatment company in Dubai. The BWRO Unit is capacity of 90,000GPD product water.

Systems and Process
Feed water to the system is processed water with raw water TDS of about 2450 PPM. The system design was based on high rejection TFC spiral wound low fouling membranes. The Reverse Osmosis Unit was selected from our RO-400 Series, model number BW-87K-2680. It produces 63 gpm of drinking water with TDS less than 50mg/L. The BWRO Unit consists of 8"x40" Hydranautics ESPA2 membrane elements, Codeline 8" diameter FRP side ported pressure vessels, controlled by microprocessor with digital TDS read out, hi/low tank level switches, hi/low pressure switches, SS multistage pump and inlet shut off valve.

Performance
From a feed TDS of about 2,450mg/L at temperature range of 25 °C, the system produces 90,000gpd of high quality water at less than 50ppm. Since the time of its start-up in January 2008, the plant has been running smoothly with minimal troubleshooting.

Industrial Brackish Water Reverse Osmosis Systems

OSMOSIS

Industrial Reverse Osmosis - 5 Parameters to Consider When Specifying Industrial Reverse Osmosis

In a power generation facility where the products are electricity and steam to provide the energy to produce that electricity, uninterrupted steam production is vital to the facility. It follows logically then that an uninterrupted source of boiler quality feed water is also vitally important. Frequently these days this means the installation and operation of a Reverse Osmosis (RO) system. The use of RO in power generation facilities has become increasingly common over the last 15 years, especially in newly built facilities. Reverse Osmosis retrofits to the boiler water pre-treatment systems of large, older power generation facilities are common as well, irrespective of the fuel source. This article presents 5 operational parameters for your consideration prior to purchasing a RO system for your Power Generation facility.

osmosis jones dvd

Industrial Reverse Osmosis Parameter #1: The Cost of Wastewater Treatment

OSMOSIS

Wastewater treatment or disposal costs are continually increasing. For those plants where the cost is becoming punitive, it might make more economic sense to design the wastewater RO system with additional stages to reduce wastewater to the minimum possible amount. In some "zero discharge" power generation facilities specialized Reverse Osmosis systems and other equipment such as crystallizers may be required. To provide an example of just how dramatically multi-staging can reduce wastewater volume consider that a 400 gpm, 400 micromho stream can be reduced to just 7.5 gpm with a 3-Stage system! The conductance of course increases dramatically along the way rising from 400 micromho to 21,320 micromho!

Industrial Reverse Osmosis Parameter #2: Choose Either Cellulose Acetate (CA) or Polyamide Composite (PA) RO Membranes Cellulose Acetate and Polyamide Composite membranes vary widely in the way their physical and chemical resistance. Fluid temperature, pH and chlorine resistance are just 3 examples of fluid characteristics that would make you favor one over the other. Operating pressure is another. CA membranes can operate at significantly higher pressures (greater than 450psi) vs. PA membranes (300psi maximum). Chlorine residual content, common in most municipal water system streams, can be tolerated just fine by CA membranes but must be neutralized by chemical means or be removed by activated carbon filtration if PA membranes are being used. A complete detailed comparison of CA and PA membrane types is contained within the white paper referenced below.

Anticipate the Maintenance Requirements of the RO System

Fouling of RO membranes will occur. Prevention is by far the best way of approaching this issue. Pre-treating the RO feed water for common foulants will reduce the maintenance burden and will ensure longer RO runs between cleaning or membrane replacement.

Industrial Reverse Osmosis Parameter #3: Prevent scaling of the RO membranes by hardness, strontium, or barium.

The three most common means of preventing scale build up in Power Generation RO systems are; feeding acid to control pH, installing a softener ahead of the RO system and feeding an antiscalant.

Industrial Reverse Osmosis Parameter #4: Prevent microbiological fouling of the membrane.

While generally not as damaging as mineral scale, microbiological fouling can significantly reduce the efficiency of a Reverse Osmosis system. Again, preventing fouling is a far more effective strategy than fouling remediation. Microbiological fouling of Reverse Osmosis systems is generally done by controlling the MB content in the RO feed water to a specified maximum using a biocide.

Industrial Reverse Osmosis Parameter #5: Prevent non-microbiological organic fouling of the RO membrane.

This is most successfully done by controlling the COD of the RO feed water. If the RO feed water is plant service water and uncontaminated (or does not contain recycled water or waste water) then the COD is almost always color or decaying vegetation. Both can be removed through proper upstream clarification or an anion exchanger. If the RO feed water contains a recycled or waste component, then the COD can be almost anything. In this case, proper upstream treatment using secondary (biological) treatment of the waste or recycled stream will be needed to reduce the COD to levels such that non-biological organic fouling of RO membranes does not occur.

Industrial Reverse Osmosis - 5 Parameters to Consider When Specifying Industrial Reverse Osmosis

OSMOSIS