technology selection tools for boiler feedwater applications (us

Water Technologies & Solutions technical paper

Find a contact near you by visiting www.suezwatertechnologies.com and clicking on “Contact Us.” *Trademark of SUEZ; may be registered in one or more countries. ©2017 SUEZ. All rights reserved. TP1165EN.docx Jun-08

technology selection tools for boiler feedwater applications (US Units) Authors: Robert Gerard and Roch Laflamme, SUEZ

introduction SUEZ Water Technologies & Solutions offers a wide range of technologies to help customers improve performance and reduce operation costs in a broad range of applications. This wide range of technologies provides an interesting challenge when trying to find the best series of unit operations to address an application. This is particularly true in view of the need to treat feedwaters that widely vary in contaminants and cost in different locations around the world. When considering environmental factors such as water conservation, wastewater reduction and when including infrastructure and labor costs in the evaluation, the analysis of the project can become complex and time consuming.

To address these issue for one specific application: the production of boiler feed water, we have developed a range of tools that allow for a quick but thorough evaluation of key factors for both new projects as well as system upgrades. These tools allow evaluation of Pretreatment options, Softening, Ion Exchange (IX), Ultrafiltration (UF), Reverse Osmosis (RO), Electrodialysis Reversal (EDR), Electrodeionization (EDI) and Thermal Evaporation and various combinations thereof. In this paper the capital and operating costs of several combinations of these unit operations are compared. The product water in all cases is high purity water to feed a high-pressure boiler or to be directly injected into a gas turbine.

The tools are designed to be used in the planning stage of a new project or system upgrade. Starting with a range of key inputs and assumptions they provide detailed information on capital and operational costs. A payback time is calculated for a system upgrade with limited input data being

required. For new systems the tools provide a comprehensive comparison of alternative system designs, without the need for a detailed design of each option. Early in the process it will become clear which technologies are most attractive, depending on the feed water analysis and site-specific factors, including input costs, and operating conditions. The result allows the utility manager or application engineer to come to a comprehensive and definitive conclusion in a matter of hours.

The tools that we have developed include:

1. Addition of a RO unit to an existing Softener, to feed a low- or medium-pressure boiler.

2. Addition of a RO unit in front of an existing conventional Demin system using Ion Exchange technology, to feed a medium- or high-pressure boiler.

3. UF plus RO to replace an existing Hot Lime Softener, to feed a medium- or high-pressure boiler.

4. RO plus EDI versus Ion Exchange, to produce high purity water to feed a high-pressure boiler.

assumptions This paper will focus on the last tool: RO plus EDI versus IX for new projects. Life cycle costs of various combinations of these technologies will be evaluated. A sensitivity study is carried out to determine the precise effect of feed and waste water cost, feed water salinity (TDS), energy, and chemical (caustic) costs on the total cost to produce high purity water. The tool provides guidance as to what combination of technologies is most attractive for a new boiler feed water project.

While economic comparisons between membrane technology and ion exchange have been conducted in

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various papers [1-3], most of these comparisons date back 5 to 10 years. Changes in chemical and water costs, and new technical developments in low energy membranes and more efficient IX, and addition of new technologies such as EDI, make it necessary to update and expand these comparisons.

In this evaluation, typical North American and European designs, feed waters, and input costs have been used. Pretreatment to the RO or IX systems is not considered, as it is assumed that the water has limited suspended solids (SDI < 3) for all system designs. In any case there would be little difference in this pretreatment, so the impact on economics is modest. Of course, the addition of an ultrafiltration system, clarifier or multimedia filter must be considered if the feed water has a high fouling potential. This paper is focused on the demineralization steps.

system design All designs are assumed to contain industrial grade equipment using a conservative design philosophy. In all cases, multiple trains are considered with an N+1 redundancy for the IX systems. The RO and E-Cell* EDI systems are designed with a minimum flow rate of 2 x 80% design flow for the smaller flows and N+1 redundancy for the larger flows. Feed water and product water storage are not considered. Storage tanks and distribution pumps between unit operations are included, when required. All systems are designed to achieve a final product water quality of < 0.1 µS/cm conductivity with silica and sodium levels each < 10 ppb. Equipment installation and commissioning costs are included in the total capital costs, using a percentage of the total equipment cost.

Design 1 is a traditional co-current regenerated ion exchange system. It contains a Strong Acid Cation vessel followed by a Decarbonator to remove CO2 (when required) and a Strong Base Anion system. Mix Bed ion exchange is used for polishing. Co-current flow is the simplest IX design. Resin is regenerated in the same downward direction as the service flow.

Design 1: Co-current Ion Exchange (CFR) or Design 2: Counter-current Ion Exchange (RFR)

Design 2 is similar to Design 1 but with a packed bed, counter-current regenerated ion exchange system. In these systems, regenerant is applied in a direction opposite to the service flow. This has the advantage of providing better water quality, higher chemical efficiency, and reduced wastewater flow (higher water recovery). Most new IX systems are of the counter-current design. For both IX options we applied a safety factor of 0.85 for cation and 0.8 for anion resin to simulate a 5 years operating period.

Design 3: Reverse Osmosis + Mixed Bed (RO-MB)

Design 3 is a Reverse Osmosis system followed by a Decarbonator (when required) and a MB polishing unit. The RO is equipped with standard medium pressure membrane elements. The mixed bed unit requires a chemical regeneration facility, bulk storage tanks, and neutralization facilities similar to design 1 and 2.

Design 4: Softener + Reverse Osmosis + E-Cell Sof-RO-EDI)

Design 4 is a sodium cycle ion exchange softener (when required) followed by a RO and final polishing by an E-Cell EDI system. Softening the RO feed water results in several advantages for RO operation: reduced fouling, higher recovery, higher specific flux and the option to raise feed pH to reduce CO2 levels in the permeate. The concentrate of the E-Cell unit is recirculated back to the front of the RO.

Design 5: Reverse Osmosis + Decarbonator + Softener + E-Cell (RO-Sof-EDI)

Design 5 is similar to design 4 except that the softener is moved to a position after the RO. Softening the RO feed water requires a considerable amount of salt for softener regeneration if the feed water hardness is

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high. The softener must be sized to accommodate the full RO feed flow rate. While a softener before the RO results is a stable RO operation, the resulting operating and equipment costs can make RO permeate softening economically more attractive. In design 5 an antiscalant is used to allow RO operation on feed waters containing high hardness and / or silica. If the RO permeate produces a water quality with a total hardness of less than 1 ppm (as CaCO3) there is normally no need for a softener. A Decarbonator or gas transfer membrane unit might need to be added to reduce the level of CO2 in the E-Cell feed water.

Design 6: Double Pass Reverse Osmosis + E-Cell (2RO-EDI)

Design 6 considers the use of double pass RO. Permeate of the 1st RO is used to feed the 2nd RO. Caustic can be dosed between the passes to convert CO2 to Bicarbonate to reduce the CO2 level in the 2nd

pass RO permeate. Final polishing is accomplished with an E-Cell unit. The double pass design provides great flexibility in the salinity of the feed water that can be tolerated (i.e. up to 10,000 ppm or higher).

tool limitations The technology selection tool evaluates all of the above-mentioned options for any given feed water analysis. It is important to point out that it is not a final design tool for each unit operation. The objective of this tool is to help determine which is the most attractive design in terms of capital and operating costs. Once the most attractive design is established, detailed optimization design calculations are required for each unit operation. Default parameters are provided for all input data, based on industry standards. These numbers can be changed to reflect local costs and conditions.

The costs for installation and commissioning are expressed as a percentage of the capital cost. For the Base Case, 40% was used for the ion exchange designs and 25% for the membrane designs. These numbers can also be changed to reflect local conditions.

feedwater analysis and base case operating data Table 1 provides the water analyses used for the comparisons. Case 1 is a low TDS water, at 48.8 ppm as CaCO3 (0.98 meq/l), which is typical in the Northern parts of Europe or North America. In Case 2 to 5 salinity gradually increases to 488.9 ppm as CaCO3 (9.78 meq/l). Case 5 could be a typical well water in a coastal area with some seawater intrusion. Case 4, with a feed water TDS of 292.7 ppm as CaCO3 (5.85 meq/l), is the base water analysis used for the initial evaluations prior to the sensitivity studies.

Table 1: Feed Water Analysis in ppm ion (mg/l), (case 4 is the base case)

Ion ppm (mg/l)

Case 1

Case 2

Case 3

Case 4

Case 5

Ca 7.5 15 30 45 45

Mg 2 4 8 12 12

Na 10 20 40 60 150

Cl 12.7 25.4 50.8 76.2 215.3

SO4 10 20 40 60 60

HCO3 25 50 100 150 150

SiO2 5 10 10 10 10

PH 7.1 7.1 7.1 7.1 7.1

Conductivity µmhos

103 206 398 590 918

TDS (ppm as CaCO3)

48.8 97.6 195.2 292.7 488.9

TDS (meq/l)

0.98 1.95 3.9 5.85 9.78

TDS (total ppm)

72.2 144.4 278.8 413.2 642.3

All other operating conditions for the base case are listed in Table 2.

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Table 2: Base Case Operating Conditions

Operating conditions

IX- Regenerant dosage H2SO4 (100%) NaOH (100%)

Co-current (CFR) 6 lb/ft3 5 lb/ft3

Counter-current (RFR) 5 lb/ft3 4 lb/ft3

Mixed Bed 8 lb/ft3 8 lb/ft3

RO Feed Pressure ( psi ) With SUEZ PRO membranes

Design 3 (RO one Pass) 230.8

Design 4 (RO one Pass) 302.8 Includes E-Cell

Design 5 (RO one Pass) 230.8

Design 6 (RO two Pass) 253.8 / 390.3 Includes E-Cell

Base cost

H2SO4 (100%) $0.05 $/lb

NaOH (100%) $0.18 $/lb

Feed water $0.76 $/Kusg

Waste water $0.19 $/Kusg

Electricity $0.06 $/KWh

Fuel cost $8.50 $/MM BTU

Salt cost $0.04 $/lb

Equipment Amortization 20 years

Interest Rate 7.0% / year

Water Temperature 59o F

In addition to the Capital Expenditures (Capex) and Operating Expenses (Opex) the tool allows the user to estimate and enter various cost savings that are site-specific. Several of these potential savings are listed in table 3. The tool starts with estimates for these site-specific savings that can be adjusted. For the Base Case savings for the membrane designs versus the IX designs are shown in Table 3. Site-specific savings may be taken into account when calculating the overall cost to produce water. Data is provided with and without these site-specific savings.

The system flow rates that have been evaluated are 110, 242, 440, 1100 and 2642 usgpm, which cover the flow rate of most industrial boiler systems.

The flow rate of 440 usgpm is used for the sensitivity analysis.

Table 3: Estimated Site Specific saving, Membrane versus IX design

Capital Cost – Estimated Site Specific Saving Value ($)

Smaller building size in foot print and height 176,115

Reduced commissioning time required 17,612

No contamination dikes required around chemical storage

14,089

Environmental reporting of chemicals eliminated or reduced

5,00

Truck chemical loading station and dedicated drains with pump to neutralization system are eliminated

16907

Acid and Caustic proof concrete, tiles, grout etc. not required

9,862

Total 239,585

Operating Cost - Estimated Site Specific Saving

Value ($)

Cation, resin cleaners will not be required 5,520

Anion, resin cleaners and or brine squeeze will not be required

4,590

Neutralization tank associated problems eliminated

3,000

More consistent water quality, reduced chance for silica breakthrough, resulting is less scaling in boiler and/or turbine

8,806

Safety improvements for Operators, Reduction in hazardous chemicals

5,000

Reduce damage / maintenance due to corrosion from acid fumes

2,000

Maintenance cost reduction on demin system, valves, pumps, others

8,806

Labor savings in possible personnel reallocation

44,029

Total 81,480

results of comparison Fig. 1 shows the capital plus installation costs for the various designs listed above, at a flow rate of 440 usgpm using the base case operating conditions listed in table 1 and 2. For the membrane options the capital site-specific savings from table 3 are shown. Significant reductions can be obtained if site-specific savings exist.

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Figure 1: Capital and Installation Cost for Base Case

Fig. 2 shows the annual operating cost for the same system designs. Equipment financing cost are included and site-specific savings for capital and operation are shown.

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Figure 2: Annual Operating Cost for Base Case

Fig. 3 shows the cost per produced 1,000 usg (Kusg) of high purity water. For the base case with relatively high TDS of 293 ppm as CaCO3 (5.85 meq/l), the membrane designs (3 to 6) show a lower cost than the ion exchange designs 1 and 2. Option 3 (RO+MB) shows the lowest cost when site-specific savings are not credited. If site-specific savings are taken into account option 4 and 5 become more attractive. For option 3 the total site-specific savings add up to $0.27 per Kusg and for option 4 to 6 the figure is $0.45 per Kusg.

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Fig. 3: Produced water cost per Kusg for base case

Fig. 4 provides a detailed breakdown of the total cost to produce water. Water cost includes the feed water plus the cost to dispose of the wastewater. For the IX options, the chemicals cost includes the acid and caustic for regeneration, plus the cost for neutralization and resin cleaning. Energy cost includes the pressure for the booster pumps, the decarbonator fan and the heating of the caustic solution. The equipment consumables are the cost of resin replacement.

For the membrane designs, the cost for chemicals include caustic dosing, antiscalant, de-chlorination, softener salt and RO cleaning chemicals. The equipment consumables costs include the replacement costs for cartridge filters, RO elements and E-Cell stacks. Energy costs includes the decarbonator fan, high pressure pumps for the RO and booster pumps. Site-specific savings are not included in this breakdown. Note that in all of the following information, site-specific savings are no longer included unless mentioned otherwise.

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Fig. 4: Cost breakdown $/1000 Kusg

The base case assumes a relatively low water and waster water cost of $0.76/1000 usg and $0.19 /1000 usg respectively. Despite this low water cost it represents a significant portion of the overall cost in all cases. For the IX designs water cost is lower due to the higher recovery compared to the membrane designs. Energy consumption is higher for the membrane designs but chemicals consumption is lower compared to the IX designs.

Figs. 5 to 7 show the capital and operating cost numbers for the base case TDS of 293 ppm as CaCO3 (5.85 meq/l). Fig. 5 shows the effect of system flow rate. Note the effect on operating cost is quite small for all system designs.

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Fig. 5: Operating cost - $/1000 usg

On the other hand, the capital cost per installed usgpm declines when the flow rate increases as is shown in Fig. 6. This effect is more pronounced for the IX designs. The reason is that the cost of the peripheral equipment for IX is not very depended on the flow rate and the cost of the IX vessels per installed usgpm declines significantly with increasing vessel diameter. For the membrane options, the cost is more linear with flow rate.

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Fig. 6: Capital & Inst. cost per usgpm installed

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Fig. 8: Cost per 1000 usg versus TDS for 440 usgpm

Fig. 7 shows the combined number of financed (capital with installation) cost and operating cost.

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Fig. 7: Total operating cost $/1000 usg

Figs. 8 and 9 show the effect of feed water TDS on water cost at the base case of 440 usgpm and at the highest flow rate of 2642 usgpm, respectively.

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The point at which the membrane designs become more attractive than the IX designs (the cross-over or “break-even” point) shifts towards higher TDS levels with increasing flow rate. Note the position of the arrows dropping down to the x-axis for the most efficient IX design 2.

For the highest cost membrane design 6 (2RO-EDI) the break-even point is at TDS 210 ppm as CaCO3 (4.2 meq/l) for a 440 usgpm flow rate and at TDS 275 ppm as CaCO3 (5.5 meq/l) for a 2642 usgpm flow rate.

The break-even points for the different designs also shift relative to each other with increasing flow rate.

The reason is that the cost lines are not smooth curves. This is caused by the need for additional equipment at higher feed water TDS levels.

At a higher CO2 level a decarbonator is often needed and a softener might be required when feed water total hardness increases.

This additional equipment obviously affects the water cost.

Fig. 10 provides a close up view of the membrane options at a flow rate of 110 usgpm. It shows that the membrane options are more attractive for all designs at a TDS levels above 75 ppm as CaCO3 (1.5 meq/l).

Design 4 (softener+RO+E-Cell) shows a steep increase in cost between TDS 100 and 200 ppm as CaCO3 (2 and 4 meq/l) due to the need for a softener equipment and the additional operating cost for salt.

Design 5 (RO+softener+E-Cell) requires a softener and decarbonator equipment but the salt consumption is less and therefore the increase is not as steep.

As a result design 4 is lowest cost up to TDS of 300 ppm as CaCO3 (6 meq/l) and design 5 is lowest cost above TDS of 300 ppm (6 meq/l).

At a low flow rate the E-Cell options (design 4 and 5) are lower cost than the option with MB (design 3) for the entire TDS range.

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At higher flow rate this changes as is shown in fig. 11. Above a TDS of 150 ppm as CaCO3 (3 meq/l) the MB option is more attractive than the E-Cell options at a flow rate of 1100 usgpm.

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Important to realize is that the site-specific savings are not included in any of these graphs. The difference in site-specific savings for design 4 and 5 with design 3 is $0.15/1000 usg for the base case at 1100 usgpm, which would make the net cost of the E-Cell and MB options equivalent at 1100 usgpm.

sensitivity analysis: effect of utility costs, chemical costs and membrane selection on produced water cost The previous graphs are all based on the base case operating conditions listed in table 2. The actual cost for electricity, water, wastewater and chemicals will have a significant impact on the final water cost and the break-even point of membrane versus IX options.

The cost of NaOH has the largest impact on the chemical cost. The cost of NaOH has more than tripled in most geographies since 2004. The resulting effect on the Ion Exchange options is considerable.

Figure 12 shows the result of varying the cost of NaOH from $ 0.18 to 0.36 per lb, for a 100% solution. This represents the current range in NaOH costs worldwide. For comparison, data is provided for the lowest NaOH cost reported in 2004, which was $0.045/lb.

The effect of NaOH cost for the membrane options is small. For this reason, and for simplicity only the $ 0.27/lb cost numbers are shown. Comparing the lowest cost IX design 2 with the highest cost membrane design 6 the break-even point ranges from TDS of 135 to 225 ppm as CaCO3 (2.7 to 4.5 meq/l).

For all other membrane designs the break-even point is at TDS 75 ppm as CaCO3 (1.5 meq/l) or below as is shown in table 4 for a NaOH cost of $ 0.27/lb.

In 2004 with caustic pricing at $0.045/lb the break-even point would have been at TDS of 340 ppm as CaCO3 (6.8 meq/l) for design 6. This remarkable difference clearly demonstrates that the effect of caustic pricing on the operating cost of an IX system is enormous.

This is one of the reasons why there has been a clear shift towards membrane technology during recent years, not only for high TDS waters, but now, for the first time, also for low TDS waters.

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Fig. 12: Effect of NaOH costing on water cost for 440 usgpm

Table 4: Break-even point at varying NaOH cost comparing membrane designs vs. design 2

Break-even point TDS PPM as CaCO3

NaOH Cost ($/lb) 0.18 0.27 0.36

Design 3 110 75 <50

Design 4 60 <50 <50

Design 5 110 75 50

Design 6 225 160 135

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The cost of electricity has also increased over the last 5 years and this will affect mainly the membrane designs, since they operate at high pressure. The effect of energy is most significant for the double pass RO design 6.

Table 5 shows a range of 50 to 160 ppm TDS as CaCO3 (1.0 to 3.2 meq/l) for design 4 and 5.

Table 5: Break-even point at varying electricity cost of membrane designs vs. design 2


Electricity Cost ($/KWh)

0.04 0.06 0.09 0.12

Design 3 95 100 115 135

Design 4 50 60 90 125

Design 5 95 110 135 160

Design 6 160 215 285 310

Fig. 13 compares design 2 and 6 showing a break-even range of 160 to 320 ppm TDS as CaCO3 (3.2 to 6.4 meq/l) for an electricity cost of $ 0.04 to 0.12/kWh.

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Design 6 Elect. $0.12/kWh

Fig. 13: Effect of Electricity cost on water cost for 440

usgpm flow rate

Fig. 14 provides the cost of produced water with a raw water cost ranging from $ 0.19 to 3.79 / 1000 usg for

options 2 and 6. The wastewater cost is kept constant in this graph at the base case value of $0.19/1000 usg.

The membrane options operate at a lower recovery than the IX options and therefore the impact of an increase in raw water cost is more pronounced for the membrane options.

The break-even point varies from TDS of 180 to 340 ppm as CaCO3 (3.6 to 6.8 meq/l). The break-even range for the other designs is shown in Table 6.

Fig. 14: Effect of Raw Water cost on produced water

cost for 440 usgpm flow rate

Table 6: Break-even point at varying raw water cost of membrane designs vs. design 2


RW Cost ($/1000 usg) 0.19 0.76 1.89 3.79

Design 3 50 100 160 250

Design 4 <50 70 100 200

Design 5 65 110 185 280

Design 6 180 215 285 340

The impact of the waste water cost is less dramatic on the produced water cost than the raw water cost but if both the raw water cost and waste water cost increase simultaneously the effect is large as is shown in fig. 15.

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Fig. 15: Effect of Raw Water and Wastewater cost on

produced water cost for 440 usgpm flow rate

Table 7 shows a TDS range of 170 to 400 ppm as CaCO3 (3.4 to 8.0 meq/l) comparing design 2 and 6.

Break-even point TDS PPM as CaCO3 RW + WW Cost ($/1000 usg) 0.19 0.764 1.89 3.79

Design 3 50 135 245 320

Design 4 <50 100 175 290

Design 5 60 150 265 340

Design 6 170 265 340 400

Table 7: Break-even point at varying raw water and wastewater cost of membrane designs vs. design 2

The final parameter analyzed is the selection of the membrane type in the RO. The base case is using SUEZ PRO elements, which are medium operating pressure, and medium rejection elements. A comparison was made with PRO LE elements, operating at lower pressure and lower rejection and PRO HR elements operating at higher pressure and higher rejection.

Fig. 16 compares design 3 (RO+MB) and 4 (Softener+RO+E-Cell). Up to a TDS of 225 ppm as CaCO3 (4.5 meq/l) design 4 with PRO HR is more attractive than the other designs. The main reason is that the softener is not required up to this TDS due to the higher rejection of hardness. The reduction in capital cost and reduced salt consumption make up for the increased energy cost. Above TDS of 225 ppm

as CaCO3 (4.5 meq/l) PRO HR in combination with design 3 is most attractive.

In this range the increase in energy consumption of the PRO HR makes up for the reduced regeneration chemical requirement of the polishing MB. The break–even point for all membrane types is less than 105 ppm (2.1 meq/l) when comparing to design 2. The design 4 with the PRO-LE membrane is shown as a dotted line above a TDS of 300 ppm (6 meq/l) because the RO product water quality at this point is no longer acceptable to the E-Cell unit.

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Fig. 16: Effect of membrane selection on produced

water cost for 440 usgpm flow rate


Membrane Type PRO LE HR

Design 3 105 90 95

Design 4 60 20 55

Design 5 110 85 105

Design 6 215 150 200

Table 8: Break-even point at different RO membrane types of membrane designs vs. design 2

In Fig. 17 both membrane type and electricity cost are varied for design 2 and 6. As expected the effect of energy cost is less pronounced in design 6 for the PRO-LE membrane. In a double pass RO arrangement this membrane is preferred over the PRO element. The average savings using PRO-LE over PRO add up to $ 0.284 / 1000 usg at an electricity cost of $ 0.06 kWh and to $ 0.57 / 1000 usg at an electricity cost of $0.12 / kWh. The water quality out of a PRO-LE double pass RO is acceptable for the E-Cell over the entire TDS range that was evaluated.

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sgDesign 2 - Electr. $ 0.06/kWh Design 2 - Electr $ 0.12/kWh

Design 6 - PRO - Electr. $ 0.06/kWh Design 6 - PRO - Electr. $ 0.12/kWh

Design 6 - PRO LE - Electr. $ 0.06/kWh Design 6 - PRO LE - Electr. $ 0.12/kWh

Fig. 17: Effect of membrane selection and electricity cost

on produced water cost for 440 usgpm flow rate

Important to realize is that Figs. 16 and 17 only apply to a flow rate of 400 usgpm and the base cost for water, waste water and NaOH. If additional parameters are varied, the conclusion as to which design is most attractive might change.

conclusions 1. Selection of the right technology to produce a high

purity boiler feed water requires careful analysis of all the parameters affecting capital and operating costs.

2. It has always been helpful to develop “rules of thumb” to guide engineers in the choice between membrane- and ion exchange-based demineralization systems. In the last 5 years this has become increasingly difficult. Due to the availability of many new products and design options, and because of radically higher energy, chemical and water costs, the old “rules of thumb” no longer apply.

3. Conditions favorable for the membrane designs are:

• High feed water TDS

• Low product water flow

• High chemical costs (particularly NaOH)

• Low water and wastewater costs

• Low electricity cost.

4. If one or more of the last 4 conditions apply, the break-even point favoring the membrane designs versus ion exchange could be as low as TDS of approx. 50 ppm as CaCO3 (1.0 meq/l) or 100 µS/cm conductivity.

5. For the TDS range and parameters that were evaluated, membrane options are always more attractive than ion exchange above a TDS of approx. 400 ppm as CaCO3 (8 meq/l) or 750 µS/cm conductivity.

6. Below 400 ppm (8 meq/l) a detailed analysis is often required. This can only be achieved using a tool that considers all parameters.

7. Site-specific savings can play an important role in technology selection. These savings generally favor membrane options.

8. The use of high rejection RO membrane elements is attractive if they allow operation of the E-Cell EDI designs without a softener. In a double pass RO design, use of low energy membranes provide the lowest produced water cost.

9. In all membrane designs it is important to optimize recovery since water and wastewater costs are significant. In this analysis design 4 (Softener+RO+E-Cell) provides the lowest cost in most situations due to the ability to operate at higher recovery.

10. The use of E-Cell EDI technology after RO is attractive versus Mixed Bed at most flow rates. When site-specific savings apply the membrane options with E-Cell produce the lowest cost water at flow rates from 110-1100 usgpm and above.

references 1. P.A. Newell, S.P. Wrigley, P. Sehn and S.S.

Whipple, An Economic Comparison of Reverse Osmosis and Ion Exchange in Europe, Ion Exchange Developments and Applications, p. 58-66, Proceedings of IEX ’96, Royal Society of Chemistry

2. S. Whipple, E. Ebach and S. Beardsley, UltraPure Water, October 1987

3. Beardsley, S., Coker, S., and Whipple, S., “The Economocs of Reverse Osmosis and Ion Exchange”, paper presented at WATERTECH ’94, Nov 9-11, 1994

TP1165EN.docx

4. Rohm and Haas, IXCalc Ion Exchange Design Software

5. Owens DL, “Practical Principals of Ion Exchange water treatment”, Tall Oaks Publishing Inc., 1985

6. BetzDearborn Handbook of Industrial Water Conditioning, 9th edition 1991

7. R. Gerard, H. Hachisuka, M. Hirose, Desalination 119 (1998) 47-55

8. Strathmann H., “Membrane and Membrane Separation Processes” Ellmann’s Encyclopedia of Industrial Chemistry, (2005), http://mrw.intersience.wiley.com [2008-2-15]

9. Bornak W, “Ion Exchange deionization for industrial users”, Tall Oaks Publishing Inc., 2003

10. Water conditioning manual, Dowex ion exchange resins, 1985

11. Kunin Robert, Amber-hi-lites Fifty years of ion exchange technology, Tall Oaks Publishing Inc., 1996

12. Paul Tan, Optimizing a high-purity water system, Tall Oaks Publishing Inc., 2007

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appendix a: technology selection tool printout for blue case

Raw water analysis Fill in yellow cells Select the unit system you want to use: 1 1=US , 2=Metric Euro € , 3= Metric $Equipment selection for Demin system, Mixed Bed, RO, Softener & E-Cell

PPM PPM / mg/l meq/l System criteriaions mg/l ion as CACO3 Please enter the average High Purity Water Production 440.3 usgpm

Calcium 45.00 112.5 2.25 The system calculation takes into account that one unit is always on standby Magnesium 12.00 49.4 0.99 ( Demin train, Mixed bed, Softener, RO & E-cell ) Sodium 60.00 130.80 2.62 A decarbonator will be selected if flow > 99 usgpm and M alk (as CaCO3) > 59 ppm Potassium 0.00 0 0.00 Decarbonator will be in place? 1 1 = Yes, 0 = No Type 1 Iron Fe+2 0.00 0.00 0.00 Regeneration effluent will be neutralised? 1 1 = Yes, 0 = No Mangenese Mn+2 0.00 0.00 0.00 What kind of acid will be used? 2 1 = HCl, 2 = H2SO4

Lead 0 0.00 0.00 Demin system: capacity based on Rohm & Haas resin SAC IR1200, SBA IRA4200 Barium 0 0.00 0.00 Regenerants dosage CFR Acid 6.0 lb/ft3 Caustic 5.0 lb/ft3 Strontium 0 0.00 0.00 Regenerants dosage RFR Acid 5.0 lb/ft3 Caustic 4.0 lb/ft3 Aluminium 0 0.00 0.00 Regenerants pricing Acid 0.05 $/lb Caustic 0.18 $/lb Chloride 76.2 107.40 2.15 Resin life expectation Cations 6 years Anions 4 years Sulfate 60.0 62.36 1.25 Water cost Raw water 0.76 $/Kusg Waste 0.19 $/Kusg HCO3- M Alkalinity 150.0 123.0 2.46 Safety factor for resin capacity SAC 0.85 SBA 0.80 Fluoride 0.00 0.00 0.00 Mixed Beds system : Nitrate 0.00 0.00 0.00 Regenerants dosage Acid 8.0 lb/ft3 Caustic 8.0 lb/ft3 pH 7.10 Resin life expectation Cations 5 years Anions 5 years Silica 10.00 8.30 0.17 Equipment Ammortization Period, months 240 7% CO2 19.49 22.21 0.44 Equipment installation cost express as % of capital cost Demin 40% RO + EDI 25% Calculated TDS 413.12 RO to MB or Softener one pass % Recovery 75% PSI increase 230.80 psi Conductivity mmhos 590 Softener to RO - one pass % Recovery 85% PSI increase 302.80 psi TOC - ppm 1.10 Two pass - RO - fisrt pass % Recovery 75% PSI increase 253.80 psi NTU - Turbidity 1.2 Two pass - RO - second pass % Recovery 85% PSI increase 390.35 psi TSS - ppm 1.0 Select the type of RO membranes to be used 1 Pro RO 365 Pump efficiency % 65%

292.720 5.85 AVERAGE water temperature 59.0 F Motor efficiency % 95%292.708 5.85 Anion regen, energy cost Fuel Cost, $/MM BTU 8.50 0.06 $/Kwh0.00% MK-3 System Parameters E-cell Energy consum. 1-Pass 0.760 KWh/Kusg

76.18 Stack life expectation 7 years Energy consum. 2-Pass 0.380 KWh/Kusg

292.720 5.85 Rectifier efficiency % 70% 40% - 95% Target Resistivity (Mohm.cm)324.322 6.49 Rectifier DC output (Volts) 300 300 or 400 VDC 10 1-18 MW cm

Water source City

Charge balance

TECTEA

Interest Rate, %

Adjusted Chloride value to be enter in cell C20

Total CationTotal Anion Electricity cost

Apendix A: Technology Selection Tool Printout for Base Case

Capital & Operating Cost evaluation RO-EDI versus Demin - Mixed bed

G E W ater & ProcessTechnologies

Options Systems

Annual Operating cost only

$/1000 usg produced

Option -1- Conventional demin system ( CFR ) follow by mixed bed 1,981,300 $ 847,100 $ 662,800 3.66 $

Option -2- Amberpack demin system ( RFR ) follow by mixed bed 1,949,500 $ 729,400 $ 548,000 3.15 $

Option -3- RO system ( 1 Pass ) followed by Mixed Bed 1,347,000 $ 515,800 $ 390,500 2.23 $

Option -4- Softener - RO system ( 1 Pass ) followed by E-cell 1,100,300 $ 538,900 $ 436,500 2.33 $

Option -5- RO system ( 1 Pass ) - Softener followed by E-cell 1,152,900 $ 537,500 $ 430,200 2.32 $

Option -6- RO two pass system followed by E-cell 1,347,000 $ 651,360 $ 526,060 2.81 $

Option # colored in red : This option is not recommended, ( TDS going into the E-Cell is too high )

Including the site specific savings impact on Capital & Operating Cost

Options Systems

Annual Operating cost only

$/1000 usg produced

Option -1- Conventional demin system ( CFR ) follow by mixed bed 1,981,300 $ 847,100 $ 662,800 3.66 $

Option -2- Amberpack demin system ( RFR ) follow by mixed bed 1,949,500 $ 729,400 $ 548,000 3.15 $

Option -3- RO system ( 1 Pass ) followed by Mixed Bed 1,299,083 $ 454,304 $ 333,464 1.96 $

Option -4- Softener - RO system ( 1 Pass ) followed by E-cell 860,715 $ 435,120 $ 355,020 1.88 $

Option -5- RO system ( 1 Pass ) - Softener followed by E-cell 913,315 $ 433,720 $ 348,720 1.87 $

Option -6- RO two pass system followed by E-cell 1,107,415 $ 547,580 $ 444,580 2.37 $

Capital cost + installation cost

Annual Operating cost including project cost & financing

Annual Operating cost including project cost & financing

Capital cost + installation cost

TP1165EN.docx

Capital & Operating Cost evaluation RO-EDI versus Demin - Mixed bedSystems

Option -1- Conventional demin system ( CFR ) follow by mixed bedOption -2- Amberpack demin system ( RFR ) follow by mixed bedOption -3- RO system ( 1 Pass ) followed by Mixed BedOption -4- Softener - RO system ( 1 Pass ) followed by E-cellOption -5- RO system ( 1 Pass ) - Softener followed by E-cellOption -6- RO two pass system followed by E-cell

Capital & Installation cost with site specific savings included

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

1 2 3 4 5 6Options

Reduced Capital & Inst. cost Site specific savings on Capital & Inst.

Annual operating cost with site specific savings included

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1 2 3 4 5 6Options

Net annual operating cost Annual financing costAnnualized Site specific savings on Capital & Inst. Annualized Site specific savings on Operation

Cost to produce high purity water cost/1000 usg or cost/m3

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

1 2 3 4 5 6Options

Net operating cost Annualized Site specific savings on Operation Annualized Site specific savings on Capital & Inst.

TP1165EN.docx

Capital & Operating Cost evaluation RO-EDI versus Demin - Mixed bed

SystemsOption -1- Conventional demin system ( CFR ) follow by mixed bedOption -2- Amberpack demin system ( RFR ) follow by mixed bedOption -3- RO system ( 1 Pass ) followed by Mixed BedOption -4- Softener - RO system ( 1 Pass ) followed by E-cellOption -5- RO system ( 1 Pass ) - Softener followed by E-cellOption -6- RO two pass system followed by E-cell

TP1165EN.docx

TP1165EN.docx

Option -6- RO two pass system followed by E-cell

GE PRO-450-PRE-FRP-60 usgpm GE PRO-300-PRE-FRP-60 usgpm 463.5 High Purity Treated # of units 545.2 # of units 463.5 usgpm Water produced

Water Tank 2 Permeate 1 2 Permeate 2 440.3 usgpm631.3 Recirc. 2

usgpm Conc. GEMK3-153.0%13.90 2.00%

First pass Second pass usgpm 9.27RO in with recirc. % Recovery 25% Reject NaOH inj. % Recovery usgpm Reject electrolyte to waste

727.0 75% 181.7 usgpm 85% 191.02 Total Reject RO + E-Cellusgpm Pump Pressure in 390.35 psi Conc. recir. 15% 30.3%

253.80 81.8 usgpmpsi

Equipment selection Capital cost Annual Operating cost Cost $/1000 usg producedRO system # of units Cost Water cost 270,200 $ 1.168 $

-raw water 251,200 $ 1.085 $ Chemical injection skid ( 2 products ) 1 8,000 $ -Waste water 19,000 $ 0.082 $

First Pass RO Treated water pumps electricity 9,380 $ 0.041 $GE PRO-450-PRE-FRP-60 2 422,300 $ RO Fisrt pass Power Cost 68,600 $ 0.296 $

caustic pump skid 1 4,000 $ RO Second pass Power Cost 79,100 $ 0.342 $Second Pass RO RO Power Cost 147,700 $ 0.638 $

GE PRO-300-PRE-FRP-60 2 306,300 $ RO chemicals cost (antiscalant + dechlore) 20,200 $ 0.087 $CIP skid for RO cleaning 1 10,800 $ RO 2- Caustic injection cost 8,680 $ 0.038 $

E-Cell Membranes chemical cleaning cost 12,100 $ 0.052 $GEMK3-15 2 326,200 $ Membranes replacement cost 28,700 $ 0.124 $

Cartridge filters replacement 7,300 $ 0.032 $Total equipment 1,077,600 $ E-Cell Power Cost 5,300 $ 0.023 $

Installation cost 269,400 $ E-Cell replacement Cost 16,500 $ 0.071 $Total equipment + installation 1,347,000 $ Total annual operating cost 526,060 $ 2.273 $

Annualized project Equipment Cost 125,300 $ 0.541 $Total annual oper. including Project cost 651,360 $ 2.815 $

All calculations are done pre-tax. No credit is calculated for the decreased tax effect of the depreciation stream. For full accounting of the project, after-tax, consult your customer accounting department for their incremental tax rate and treatment of depreciation.

RO reject to waste

TP1165EN.docx

Other Benefits of using RO/E-Cell technologies versus Demineralizers that can possibly be translated into Capital SavingsSite specific savings, has to be validated by the Customer, all may or may not apply.

Value176,115 Smaller building size in foot print and height

17,612 Reduced commisioning time required

14,089 No contamination dikes required around chemical storage5,000 Environmental reporting of chemical eliminated

16,907 Truck chemical loading station and dedicated drains with pump to neutralization system are eliminated0 You can enter here others benefits that are not listed0 You can enter here others benefits that are not listed0 You can enter here others benefits that are not listed0 You can enter here others benefits that are not listed

9,862 Acid and Caustic proof concrete, tiles, grout etc. not required0 You can enter here others benefits that are not listed

239,585 Total $ claimed for other annual benefits 22300

Other Benefits of using RO-E-Cell technology versus Demineralizers that can possibly be translated into Operating SavingsSite specific savings, has to be validated by the Customer, all may or may not apply.

Value5,250 Cation, resin cleaners and or brine squeeze, will not be needed

4,590 Anion, resin cleaners and or brine squeeze, will not be needed anymore

3,000 Neutralization tank associated problems, maintenance cost + time delay0 More consistent water quality, reduced chance for silica breakthrough resulting is less scaling in boiler or turbine

5,000 Safety improvements for Operators, Reduction in hazardous chemicals8,806 ecomagination - less "salts" discharged to the environment, no need to desalt downstream!!

0 Value of "bad" regenerations that have to be repeated2,000 Reduced damage / maintenance due to corrosion from acid fumes

0 You can enter here others benefits that are not listed8,806 Maintenance cost reduction on demin system, valves, pumps, others

44,029 Labor savings in possible personnel relocation or reallocation81,480 Total $ claimed for other annual benefits

technology selection tools for boiler feedwater applications (us

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