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EDL (Envitech Distribution Limited), PM Tower, 5th fl, 731 Asok Din Daeng, Din Daeng, Bangkok 10400. Phone: 026428919, Fax: 026428920, Mobile: 66 1977 6262 Email: [email protected], web site: www.scalewatcher.com

EDL (Envitech Distribution Limited) Boiler System Water Treatment.

Introduction. Since 1989 equipment is being manufactured to prevent mineral scale precipitation by using a coil wrapped around the liquid carrying pipe. Mineral ions in the liquid will be affected by the generated magnetic and electric field, starting precipitation (crystal growth) in the bulk of the liquid, rather than on pipe walls or other surfaces. These crystals will go down the drain or stay suspended in the liquid in case of a circulation system like cooling towers or heat exchangers. Good results have been achieved in shell and tube heat exchangers, small and large cooling towers, condensers and compressors in power plants, steam boilers, process water etc... Existing mineral scale layers are gradually removed, decreasing the temperature differential for cooling towers and heat exchangers. Often a payback time of less than two years is achieved. Advantages of Scalewatcher:

1. No plant shutdown for installation. 2. No chemicals needed. 3. No maintenance of the equipment. 4. Low power consumption. 5. Capital equipment will last longer.

Other beneficial effects of the treatment: 1. Prevents corrosion in pipework. 2. Prevents settlement of zebra mussles (shell fish) in plants using sea or river water for cooling purposes. 3. Bacterial counts in cooling systems will be less due to the fact that the breading ground (scale layers) for bacteria is removed. 4. Reddish water and rust (Fe203) in iron pipes will disappear replaced by a thin black layer of magnetite (Fe304).

The product is sold under the trade name Scalewatcher in major parts of the world and is produced in the Netherlands for Europe and the Middle East, the United Kingdom, the United States of America for North America and in Vietnam for the South East Asian market.


How It Works

Scalewatcher´s patented technology works by producing a complex frequency modulated waveform. Reacting to the varying applied field the Scalewatcher creates an induced electric field inside the pipe whereby the crystal growth of scaling minerals in the water is promoted. Crystals remain suspended in solution and no longer contribute to the build-up of hard pipe wall deposits. Existing scale layers are softened and loosened scale crystals are removed from the system by the water flow. The Lorenz Force F=q.E+q.vxB N describes the total force on charged particles and ions in a magnetic and/or electric field. Scalewatcher: F=q(E + vxB) Magnet: F=q.vxB Newton Where: F = the Lorenz Force expressed in Newton q = the charge of a particle or ion expressed in Coulomb E = the electric field strength in Volt/meter v = the velocity of the particle or ion expressed in meter/second B = the magnetic induction expressed in Tesla. F, E, v and B are all vectors.

So the incoming particles and ions in the water are subject to this Lorenz Force.

Particles in the water have by nature a negative charge and have an electric double layer of positive and negative ions around them. This stable situation can be distorted by heat, ultra sonic sound, chemicals and also an electric and/or magnetic field such as created by Scalewatcher. The distortion may change the particle into a nucleation site. Positive and negative ions in the bulk of the water will attach to it forming a crystal. The so formed crystals will float with the water down the drain. A side effect of forming crystals out of dissolved carbonate scales is that small CO2 bubbles are formed. These bubbles will soften the existing old scale layers and will then gradually dissolve in the water.


THE BENEFITS OF INSTALLING SCALEWATCHER ON BOILER SYSTEMS

Fire Tube Boilers

Boiler Water Treatment

Management's Responsibility

There is a definite legal and moral responsibility on the part of the management to ensure reliable, continuous and efficient operation of the steam boiler and to ensure that no damage to equipment or physical hazard occurs.

Water, contains many impurities and the design and operation of modern steam boilers is such that proper feed water treatment is an absolute necessity.

Boiler Scale and Deposits

Boiler scale is caused by impurities being precipitated out of the water directly on heat transfer surfaces or by suspended matter in water settling out on the metal and becoming hard and adherent. The evaporation in the boiler causes impurities to concentrate.

In untreated boiler water, the formation of scale is like a "back to nature" movement. As minerals are deposited out from water they form many types of crystalline and rock-like structures. The most common scale in boilers is due to carbonate deposits caused by hardness.

Carbonate scale is usually granular and sometimes very porous. A carbonate scale can be easily identified by dropping it in a solution of hydrochloric acid. Bubbles of carbon dioxide will effervesce from the scale.

Sulphates scales are harder and more dense. A sulphate deposit is brittle and does not effervesce when dropped in acid. Silica scales resemble porcelain. This scale is very brittle, is not soluble in acid, and dissolves slowly in alkali.

Iron deposits are very dark colored. They are either due to corrosion or iron contamination in the water. They are soluble in hot acid giving a dark brown solution.

Problems Caused by Scale

The biggest problem caused by scale is overheating and failure of boiler tubes. The thermal conductivity of porous boiler scale is similar to insulating brick. The scale acts as an insulating layer and prevents an efficient transfer of heat through the tubes to the circulating water. The reduction in thermal conductivity means lower boiler efficiency which in turn leads to overheating and may result in the softening, bulging or even fracturing of the boiler tubes. Boiler scale can also cause plugging or partial obstruction of circulating tubes in a water tube boiler, which again causes starvation and overheating of the tubes.


Another important aspect is that corrosion may occur under the boiler scale. In general, boiler scale causes

a. Increased fuel bill by decreasing the operating efficiency b. Thermal damage c. Unscheduled down-time d. Increased cleaning time and cleaning costs e. Reduced working life of a boiler.

Corrosion

Corrosion is one of the most serious problems in boiler operation. Dissolved oxygen and carbon dioxide are the two gases which are mainly responsible for this.

What is corrosion? Stated simply, corrosion is the reversion of a metal to its ore form. Iron, for example, reverts to iron oxide as the result of corrosion.

Corrosion takes many forms, it may produce general attack over a large metal surface or it may result in pinpoint penetration of metal. Corrosion often occurs in standby boilers due to the exposure of wet metal to the oxygen in the air.

CORROSION DAMAGE IS IRREVERSIBLE.

Magnetite

Boiler steel is often protected from the effects of corrosion by a thin layer of magnetite. This thin film is found to be most stable in the pH range 11-12 and provided the film remains intact, the underlying steel will not corrode. Dissolved oxygen constitutes the main danger to this protective sheath. An additional advantageous property of a magnetite film is its excellent thermal conductivity, i.e. heat transfer efficiency is promoted by magnetite.

Caustic Cracking

This is a special type of corrosion, often referred to as caustic embrittlement. Boiler metal failure is characterized by continuous mostly inter-granular cracks. For this type of cracking to occur

a. The metal must be under stress b. The boiler water must contain caustic, and c. There must be a leakage of steam or boiler water.

This is a particular problem in rivetted boilers and the rolled tube ends in modern boilers are also vulnerable areas of attack.

Carryover

Carryover describes the contamination of the steam with boiler water. It can be due to FOAMING when bubbles are formed on the surface and are carried out with the steam. High concentration of solids in the boiler water cause foaming, as well as soil and other contamination of the feed water.

Carryover can also be due to PRIMING when slugs of boiler water are thrown over the steam. This is often caused by excessive steam demand or rapid increase in load. In severe cases of priming top tubes can be exposed and subject to overheating. The effects of carryover can be quite serious. The steam will be contaminated; water hammer may occur; slugs of boiler water can damage machinery; dissolved or suspended solids in the boiler water will deposit in the steam and condensate system.


POOR WATER GIVES POOR STEAM

In conclusion, water impurities cause scale and steam contamination, dissolved gases in water cause corrosion. These impurities lead to scale formation and result in inefficient operation, increased fuel cost and boiler damage. To protect a boiler from thermal damage and from the irreversible damage caused by corrosion, effective boiler water treatment is an absolute necessity.

EFFECTIVE BOILER WATER TREATMENT IS A COST SAVER

Chemical deposits or scaling on the water side can represent a significant loss in efficiency, but are potentially even more serious because they are such good insulators. Since they reduce the heat transfer and thereby increase the gas side metal temperature this can result in premature tube failure. Even a thin layer of scale causes a marked increase in tube temperature and an accompanying decrease in expected life. Water-side deposits are caused by chemical compounds found in raw water. The tendency to form scale deposits can be controlled through an active water treatment program (Scalewatcher) prescribed by specialists that is strictly followed to prevent efficiency loss and premature equipment failure.

Mineral impurities in boiler water can also cause other operating problems, for example foaming and the consequent moisture carryover into the steam line. Most processes specify dry steam because this moisture carried over contains mineral impurities that cause fouling of downstream steam heating equipment.

Blow down is the periodic or continuous water removal used to control the buildup of dissolved solid levels in the boiler, thereby preventing scaling and water carryover. During the blow down process, a controlled amount of high-solids bearing boiler water is discharged to the sewer and replaced with feed water. Blow down is controlled to limit the desired "dissolved solids" level.

After installing Scalewatcher for your boilers expect the following results:

1. Reduced chemical costs. 2. Reduced fuel costs. Scaled surfaces represent a loss of heat transfer and increased fuel consumption.

Scale efficiency relationship table – based on pure calcium and magnesium scale: 3. Reduced maintenance costs. Extended shutdown intervals. 4. Improved fuel consumption due to increased boiler efficiency. 5. Improved water consumption – less blow down. Initially the need to blow down will be increased as

Scalewatcher is de-scaling, this is represented by a higher than normal TDS reading. 6. Scalewatcher is environmentally friendly. 7. No shutdown required for installation. 8. Scalewatcher power consumption is very low – approx. 5 Watts/Hr for boiler applications. 9. Scalewatcher has a 5 years warranty with an expected 20 plus years of trouble free operation, this

represents 18 plus years of savings after the R.O.I. (Return on Investment) 10. Return on investment usually up to two years.

Thickness of scale mm Loss of Efficiency 0.4 4% 1.5 11% 3.0 18% 4.5 27% 6.0 28% 10.0 48% 12.0 60%


Fire Tube Boiler :- In fire tube boilers , the flame and hot gases are confined with in tubes arranged in a bundle with in a water drums. Water circulates on the outside of these tubes. As the water changes to steam , it rises to the top of boiler drum and exits though a steam header. The fire tube boilers have a capacity restriction up to 20 kg/cm2 pressure because of design limitation.

Water tube boiler:- The water tube boiler differs from the fire tube boiler in that the flame and hot combustion gases flow across the outside of tubes and water is circulated within the tubes. Combustion of fuel occurs in a furnace and some of the water tubes usually form the furnace walls . In a simple water tube circuit steam bubbles form on heated side of tubes . The resulting steam water mixture has a density below that of cooler water on the unheated side and rise, creating a circulation through the system . The steam bubbles rises until they reach the steam drum where steam is released from the water into vapor space.

Boiler scale creates a problem in boiler operation because scale typically possesses a low thermal conductivity (relative to a clean metal surface). The presence of scale is equivalent to having a thin film of insulation across the path of heat transfer from the furnace gases to the boiler water. This heat-insulating material retards heat transfer and causes a loss in boiler efficiency. Stack gas temperatures may increase as the boiler absorbs less heat from the furnace gases.

Heat transfer may be reduced as much as 10%-12% by the presence of scale. A scale approximately 1/8-inch thick may cause an overall loss in boiler efficiency of about 2%-3% in fire tube boilers as well as in the convective sections of water-tube boilers. Even more important than the heat loss is that scale can cause overheating of the boiler tube metal and can result in subsequent tube failures. Costly repairs and boiler outages are the result of such a condition.

Scale formation in boilers can be controlled by Scalewatcher in combination with the proper operation and maintenance of all make-up and feedwater pretreatment systems. Scalewatcher maintains solubility of scale-forming solids within the boiler.

Typical Plant Layout and Scalewatcher Positioning


After 3 months Scalewatcher is progressing in a Fire Tube Boiler – removing scale and forming a black

magnetite layer.

Pipe after Scalewatcher Unit at First Apparel (Thailand) Co., Ltd. Pipe before Scalewatcher Unit

Why do we recommend Scalewatcher Units are fitted as shown in the “Typical Layout” above.

1. Scalewatcher Units are physically protecting the majority of the system from scale build up. 2. The Scalewatcher unit before the sand filter will assist the softener to remove the maximum

amount of hardness. (Softeners remove hardness but why do we still see scale build up?) 3. The Scalewatcher on the condensate return is essential because with most boilers that

operate with a high TDS carryover to the steam system is prevalent.

Boiler scaling is very expensive to control. The easiest control is minimal or no chemical usage. The less chemistry you put into your boiler, the longer it will operate problem free and the lower your costs are. Using a pure water feed with minimal or no chemical additions, you will:

1. Minimize chemical costs

2. Greatly decrease the frequency of blowdown in your feed and bleed.

For example: If your capacity is 1000 gallons and the feedwater is at 200 ppm, evaporating 50% and refilling, then blow down at 1200ppm, you get about 10 cycles (each cycle adds 100 ppm). If you put 5 ppm in, you get 478 cycles (each cycle adds 2.5 ppm).

If you purge 1000 gallons, per blowdown, that is a savings of 46,800 gallons over one 1200 PPM cycle!

1. Reduce maintenance and downtime 2. Extend boiler life


Boiler feedwater costs are associated with the following parameters

• pH • Hardness • Oxygen and carbon dioxide concentration • Silicates • Dissolved solids • Suspended solids • Concentration organics

Usual treatments include:

1. Water softening for hardness. Calcium and Magnesium (hardness ions) are removed by the softening process. Ca and Mg are exchanged for sodium ions on an ion exchange resin. Hardness in water causes scale. Scale is usually Calcium and/or Magnesium carbonate that precipitates out as the ions are concentrated in the boiler. Scalewatcher assists softeners to further reduce hardness.

2. Pre evaporation, a membrane process or deaerator can be used to remove Oxygen and CO2 down to very low levels for high pressure boilers. Scalewatcher forms a thin film of magnetite on boiler water side surfaces protecting against corrosion and improving heat exchange.

3. Silicates cause another type of scaling and can be removed with ion exchange or a membrane process. Membrane systems are preferred where dissolved ion concentrations are high because of operating cost considerations. High silicate levels are difficult and may require co-precipitation with other ions or high temperature caustic regeneration of ion exchange system. Scalewatcher prevents silica scaling forming.

4. Dissolved solids can be removed by ion exchange or Reverse Osmosis membrane processes. The results are similar with ion exchange able to remove practically all the ions and RO able to get very close with lower operating and maintenance costs. With high TDS concentrating, a combination of the two can be very cost effective. The advantage of removing dissolved solids is that you can greatly increase the time between blowdowns as the makeup water is almost void of solids. It takes much longer to get to the concentration when the boiler should be blown. Initially Scalewatcher increases the TDS due to existing scale removal.

5. Suspended solids are removed by filtration. Normally, you would want a backwashing filter followed by a fine cartridge filter for the best results. The backwashing filter can take high solids loadings before flows are reduced and is self cleaning. The polishing filter makes sure any residual material does not get through. Scalewatcher protects the internals of the filtration system from scale thereby increasing the lifespan of the filters and polishers.

6. Concentration of organics is less of a problem in a properly designed feedwater system because much less chemistry is required to maintain the boiler. It is much easier to balance the system, and in some systems, no oxygen scavenger is required. Scalewatcher’s action of converting Fe203 into Fe304 means that less 02 scavenger is required.


Water Softener

Fire Tube Boiler

How to Evaluate Scalewatcher Performance for Industrial Boilers Introduction: Industrial Boiler systems vary with each different process. The one area where these process systems remain fairly constant is the “Water Chemistry”. ScalewatcherTM is not responsible for the water chemistry in any process plant, however, ScalewatcherTM can advise from previous experience what the process operators should observe after the installation of Scalewatcher. Water test kits are available on the market and are inexpensive and easy to use if instructions are followed properly. Evaluation Preparation:

Before Scalewatcher installation:

1. Carry out the recommended water tests for your boiler and record. 2. Record your system temperatures. 3. Record your boiler make-up water usage. 4. Take photos of the problem areas e.g. piping, boiler internals. Record scale thickness and observe rusted

areas if any.


Evaluation Duration:

What you should expect to observe and recommendations:

1. More than normal increase in boiler water TDS. This is the first indication that Scalewatcher is working to remove existing scale. Recommendation is to blowdown until the desired TDS level is achieved. Reduce scale inhibiting chemicals.

2. Increase in boiler water PH. Recommendation is to reduce your PH chemical injection. 3. Increase in Chlorides if the system is using chlorine injection. Reduce the chlorine chemical injection if

possible. 4. Other parameters from water test results (e.g. alkalinity) should be treated as above to keep the boiler

water within the desired limits at all times. Evaluation Completion:

1. Take photos at the same areas before Scalewatcher installation. At the least it should be observed that the

scale thickness has dramatically reduced and is soft. 2. TDS will level out if descaling is complete. 3. Evaluate chemical water tests. 4. Less blowdown required. 5. In steel pipe systems and boiler internals it may be observed that previously rusty areas will have been

converted to black magnetite.

SCALE THICKNESS IS RELATED TO TIME TAKEN TO CLEAN THE SYSTEM - THE NORMAL EVALUATION PERIOD IS RELATED TO SCALE REMOVAL PROGRESS.


R.O.I. (Return On Investment) calculations: 1.) Cost before scale watcher installation

Washing filter system. Sand filter, washing 2 time/day by water = ……….$$$$/time x 2 x 30 days/month

= ……… $$$$/month Carbon filter, washing 2 time/day by water = ……….$$$$/time x 2 x 30 days/month = ……….$$$$/month Resin filter, washing 2 time/day by salt water = ………. $$$$ x 2 x 30 days/month = ……..…$$$$/month

Total operation cost = $$$$/month

Chemical cost for boiler Chemical for prevent scale in the boiler = …….. …kg/month x …..$$$$/kg = ……….. $$$$/month

Chemical for prevent corrosion in the boiler = ………...kg/month x …….$$$$/kg = ………....$$$$/month

Total of chemical cost = $$$$/month

Annual cost for cleaning steam boiler Annual cost for cleaning steam boiler average = ……….. $$$$/month

Grand Total cost = ………A…… $$$$/month

Cost after scale watcher installation

Scalewatcher investment 2 sets = D $$$$. Washing filter system

Sand filter, washing 2 time/day by water = ……....$$$$ x 15 days/month = ……... $$$$ Carbon filter, washing 1 time/day by water = ………$$$$/day x 30 days/month = ……... $$$$ Resin filter, washing 1 time/2 day by salt water =……….$$$$ x 15 days/month = ………$$$$ Total cost = $$$$/month.

Grand Total cost = ………B…….$$$$/month

The comparison before and after installing Scalewatcher - after installation your cost saving is about = A – B = …….C $$$$/month. Therefore, payback is within = D/ C = ……E…months. Profit after 20 Years Scalewatcher life expectancy = (20 - E/12) x (C x 12).


Scalewatcher (Thailand) Co. Ltd. 731 PM Tower 5th. Floor Asok-Dindaeng Rd, Dindaeng Bangkok 10400 Tel: 02 6428919 Fax: 02 642 8920 Email: [email protected] Website: www.scalewatcher.com

BOILER WATER ANALYSIS SHEET

Company: Sample No: Sample Date: Report No: Report Date:

Result Parameter @ 250C

Boiler 1 Boiler 2 Boiler 3 Boiler 4 CondensatePH Conductivity (us/cm) Total Dissolved Solids (ppm as NaCL) Total Hardness (ppm as CaCO3) Ca-Hardness (ppm as CaCO3) Mg-Hardness (ppm as CaCO3) M-Alkalinity (ppm as CaCO3) P-Alkalinity (ppm as CaCO3) Bicarbonate (ppm as CaCO3) Total Iron (ppm as Fe) Chloride (ppm as Cl) Residual Chlorine (ppm as Cl2) Turbidity

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