Load Banks

By Ilan Toledano
Friday Jan 27, 2012 9:20pm UTC
 

Wind energy industry has becoming a large contributor of the renewable energy production because of its high energy efficiency and reliability along with its revenue growth for the U.S. Government and Government of Canada. In a wind farm, various turbine testing must be done prior and after the windmill construction in order to ensure perfect functionality during the operation. Running a wind turbine system at lower efficiency may significantly increase the organization’s project cost and, in addition, a faulty process could cause negative environmental impacts such as unnecessary energy wastes. In order to verify the functionality of the wind turbine system, a resistor load bank is usually considered to test the power generator. A load bank is a series of resistors that is used to generate a dummy electrical load in order to test the turbine’s actual performance. The generated load is used to mimic or simulate the generator’s operation in a repeatable way [1]. The applied load can be adjusted to produces various inputs (steady or unsteady) to the generator sets. In this way, malfunctioning issues and causes could be discovered during the maintenance rather than the actual operation. As a result, the chances of a power supply interruption and blackout will greatly decrease with the use of load banks.

A resistive load can be generated by convective heat. A cost effective method to generate this type of heat is to use forced-air heating which is provided by duct air heaters. The duct heater can be then used as the load bank to generate dummy loads for the wind turbine power generator. Even though a duct heater is commonly used for air duct, a large capacity air duct heater can, however, expand its capability into a resistor load bank. The basic design of a forced-air duct heater consists of multiple bended heating elements tubes attached to a supporting flange (Figure 1).

 

Figure 1 - WATTCO™ Forced-Air Process Duct Heater

The convective heat is generated from the heating elements when the forced air is made contact with the heater. The electrical connections are wired on the mounting flange while the circuit design is entirely based on the individual target application. A terminal boxing enclosure is available to protect the air duct heater from physical disturbance. To explore further about possible types of duct heaters that could be used as load banks, visit WATTCO™’s website or contact our technical representatives for additional information.

The applied load from the duct air heater can be controlled by a temperature controller which is used to adjust the applied temperature. A calibration from the applied temperature into electrical load can be used to ensure that the heater will provide the proper load for the testing. The heater temperature controller is particularly useful for testing a generator’s capacity with multiple loads. Testing a power generator with various ranges of load can fully test its stability [2]. Since the duct heater is designed to be flexible to use, it can be used for regular generator maintenance. Periodic generator tests are essential to maintain the stability and endurance of the windmill process. In addition, regular testing can reduce the amount of potential delays on large repair and replacements for the defective power generator.

In addition to the windmill system testing, an air duct heater can also be used to remove unwanted chemical build-ups of the turbine system, such as carbon accumulation, from the equipment since many organic and inorganic compounds dissociate from metallic structures at high temperature. This could be done simultaneously with the regular load testing/maintenance while minimizing the physical cleaning time.

Duct air heaters could also be used in energy industries other than in wind power generation. Any industry that requires load testing on power generator sets or batteries could use load banks to test the power system’s capability. The function is similar to the wind turbine testing which is to force the power system to perform as it is designed by applying the artificial load.

The design of the load bank air duct heater will be customized based on the target windmill’s structure and specification. Information such as the environment, generator design and load requirements of the wind turbines are essentially needed in order to build an efficient load bank that will fit to your target application. Therefore, feel free to contact WATTCO™’s technical supports for information, inquiries about the load bank design or the price quote.

 

Reference

1.        United States. Greenhouse Gas Technology Center Southern Research Institute. Test and Quality Assurance Plan. U.S. Environmetal Protection Agency, Oct. 2006. Web. Jan 4 2012. p. 1-2 to 1-4, 2-5 <http://www.epa.gov/etv/pubs/600etv07056.pdf>

2.        United States. Intertek Carnot Emission Services. Specializing in Offroad Engine Services. U.S. Consumer Product Safety Commission, July 30. 2011. Web. Jan 4 2012. p. 6 to 7

< http://www.cpsc.gov/library/foia/foia11/os/intertek2010.pdf>

Marine Heaters

By Mike Lowery
Wednesday Dec 21, 2011 2:46pm UTC

Marine Heaters

Process electric heaters can be used for many different applications, for example, cleaning, pre-heating, frost protection, etc. Unlike other types of heating equipment, an electric source is sufficient to fully operate a process electric heater. Immersion heaters can be used for small or large scale operation in an energy efficient way to provide the necessary heating. There are various types of electrical immersion heaters for marine operation: flanged, circulation and over-the-side. The selection of the immersion heater type depends on the target application’s environment and condition.

Immersion heaters are particularly useful in marine and military operation since there are many instances in a ship that requires quick heat generation. For example, a high demand of hot water is required for both cleaning and drinking. Sanitization is very important to prevent disease outbreak in the ship and hot water is the cheapest way to sterilize unwanted biological organisms. An approximately temperature of 77°C is sufficient to disinfect ship equipments such as empty vessels and tanks [1]. WATTCO™ offers a great numbers of marine heaters to provide the precise heat for marine application.

A flanged electric marine heater can be used to warm the temperature of the potable water supply tank. This is generally done by inserting the immersion marine heater into the water tank reservoir (Figure 1). Other than water application, flanged heaters can also be used to preheating different liquids, for example, such as oil tank for ship transportation.

 

Figure 1 - Flanged Immersion Heater in a Water Tank

 

A flanged marine heater consists of multiple bended metallic tubes, also known as the heating element, welded on a steel flange (Note: only one tube is attached to the flange in the illustration of Figure 1). Each heating element contains a Nickel Chromium resistor wire enclosed by Magnesium Oxide and a metallic sheath on the surface for protection (Figure 2). The coiled resistor wire generates the heat by the electrical source and the heat distributes evenly across the entire tank. A flanged immersion marine heater is designed to compactly fit in the target container.

 

Figure 2 - Components of a Heater Element Tube

If the target liquid or gas requires mobility during the marine transportation, a circulation marine heater is suitable for the application. A circulation heater offers precise heating control to sensitive liquids for long transportation. The viscosity and the state of a liquid (such as oil) may change during the course of transportation. However, by adding motion to the liquid will maintain the desired condition over the travelling time.

A circulation marine heater generally consists of a flanged heater, pump unit and a cylindrical casing (Figure 3). The liquid motion is created by using a pump which circulates the medium in a closed loop flowing pattern. The insulated steel casing protects the liquid from the environment in order to maintain the flow rate and temperature of the moving liquid. This vessel casing chamber provides the insulation which reduces the heat loss compared to standard tank heaters. The mounting (vertical or horizontal flow direction) of a circulation heater depends on the application.

Since this electric marine heater is used for precise temperature control operation, it is recommended for customers who are interested in the product to contact WATTCO™’s consultants about their target application.

 

Figure 3 - Illustration of a Circulation Heater

 

A circulation marine heater can also be used as a fresh hot water maker. Filtrated and purified seawater can be continuously heated in order to provide a large volume of hot water during high demand period, for example, in emergency time.

If the standard flanged marine heater doesn’t fit in a vessel, an Over the Side heater would be perfect to use for narrow openings. An over the side marine heater has various shapes depending on the container’s limiting open space. A particular bended over the side marine heater is illustrated in Figure 4.

 

Figure 4 - Example Application of an Over-the-Side Heater

The over the side heater is particularly efficient for precise heat control despite its smaller size. An important application of this marine heater is the frost protection. This applies for liquid containers marine transportation in cold environment. In order to prevent the target chemical liquid to freeze or crystallize, an over-the-side marine heater is recommended to protect the valuable product. Unlike other electric marine heaters, the over the side heater does not require to completely empty the liquid tank before the heater removal. 

There are virtually unlimited numbers of applications for electric marine heaters. The examples that were listed in the article only describe a small portion of many applications. For more information on the usage and specification on process electric heaters, please visit WATTCO™’s website or contact the support representative for further inquiries.

 

Reference

1.      United States. Food Safety and Environmental Services. Office of Environmental Health. Food Equipment Cleaning and Sanitizing: Water Chemistry and Quality. Arizona Department of Health Services, 24 Aug. 2011. Web. 19 Dec. 2011. <http://www.azdhs.gov/phs/oeh/fses/fecs_wcq3.htm>

 

Freeze Protection and what you need to know

By Louis Karras
Tuesday Dec 6, 2011 10:47pm UTC

Freeze Protection: With many weather conditions being unpredictable year after year, many companies look at protecting their mediums whether they be water based, or oil based from freezing through the winter months. In a study conducted by the University of California for Atmospheric Science in 2000*, it was regarded that more economic losses occur due to freeze damage in the United States than to any other weather related hazard. 

The industries that require freeze protection

The most common industries generally affected over the winter months are the Oil and Gas industry, Water treatment plants, Transportation industry, Agriculture, and Mining industry. These industries have many applications that require their product to be outside, and exposed to extreme temperature for a long period of time. With water based products it is vital to provide freeze protection, as they begin to crystallize and freeze at 0C / 32F / 273.15 K. Keep in mind, that providing a heat source alone is not always the best solution, making sure that tanks or reservoirs are properly insulated is very important to assuring that your medium doesn’t freeze.

When dealing with oil-based products however, it becomes more difficult the colder the weather temperature changes. Fuel oils (both clear Diesel fuel and dyed home heating oil) do not freeze, but rather turn into gel or a thicker wax. This process begins to occur bellow 32F, and continuously hardens the colder it gets. Once the temperature drops bellow 15F the wax or paraffin in the fuel begins to crystallize and separate from the oil, making it extremely difficult to handle or to remove from it’s container. In certain applications where these fuel oils are transported through a pipeline, it is highly recommended to insulate any piping that may be exposed to extreme temperature and winds, in order to avoid any clogged pipes.

For Motor oil, Gear oil and Hydraulic Oil each has a different freezing temperature range, for instance Motor working oil (10W30) freezes at –20F, but from 50F, to 0F the viscosity of the oil becomes more and more difficult to handle. With Gear oil and Hydraulic oil it’s freezing temperature is set for –10F and same as motor oil would become less viscous the colder it gets. However there are certain oils that do work bellow freezing temperature and those are generally the thicker kind of Motor Oil’s like 15W30, which freezes at  -55F.

The Definition of Freeze Protection 

Freeze protection means that you don’t want your tank’s temperature to go bellow 32F, or else the liquid will freeze. To best protect against freezing is to insulate your tank, this allows having a heat loss of approx.5%, versus a 35-45% heat loss without any insulation. Since your tank holds a certain amount of gallons, and you’ve decided to only use one heater, insulating your tank is a must. This will avoid having 2 different temperature zones, in your tank. Keep in mind that if your heater is on one side, heat transfer will take some time before getting to the other side, but with insulation it will get there faster. The most efficient way however is to install 2 or more heaters depending on the size of your tank.

The most difficult part in protecting your medium from freezing is determining how much power is enough. The first thing you require is to understand your tanks environment and it’s surroundings. It’s best to search through historical charts to determine how cold it can get at your location with and without the wind. However the weather is always unpredictable, and you have to keep in mind that if your tank is well insulated, and the heater is working with the proper controls then during the freeze period you should be well protected to bare the storm. In certain regions around the world the temperature will reach bellow 32F, and stay bellow 32F for a considerable amount of time, this is where the right amount of power and insulation for your tank play their most important role in protecting you against freezing conditions.

Heating Formulas 

These are the formulas that’s generally used in the heating industry to determine how many Kilowatts would be required to heat a tank filled with either Water or Oil:

 

§         [Formula for heating water in a tank]
(# Of Gallons) x (Delta Temperature in Fahrenheit) / (372) x (# hours)  = Kilowatts required

§         [Formula for heating oil in a tank]
(# Of Gallons) x (Delta Temperature in Fahrenheit) / (860) x (# hours)  = Kilowatts required

How much power do you need for Freeze protection

How much power is required to protect your Water or Oil tank? For this exercise we will use the formula above, and take into consideration that we will be heating 30,000 gallons of water. The next step is to determine the delta temperature, the ambient temperature of the water tank will start at approx. 40F and your target temperature will be 80F, that’s a Delta Temperature Rise of 40F.

We would then use the formula, (30,000 gallons) x (40F DT) / (372) x (24 hours) = 134KW/per hour. This means that for every hour that passes your 30,000 gallons of water will increment by approx. 1.66F/ per hour, for the next 24 hours. If your tank doesn’t have any insulation, and the exterior temperature of the tank were to drop bellow 32F, you would be losing up to 40% of the heat from the side wall of your tank every hour, depending on the thickness of your tank walls. With your tank being set at a target temperature of 80F, it would then drop approx. 32F every hour, and your heater would only increase the temperature by 1.66F, which means that half the tank would be frozen in approx. 2 to 3 hours. The other half of the tank where the heater is located would be preparing to crystallize, while a cavity of ice will begin to form around the heater.

This is the primary reason we recommend insulating any tank that’s exposed to the outside weather conditions. It’s the first line of defence for freeze protection, because it will shield your tank from the extreme winds and temperatures of winter. With insulation you only lose approx. 5 % if the temperature drops bellow 32F, which if we were to take the same example as above, at 80F you would lose approx. 4F from your outer walls every hour, but with a 134KW heater your increase would be approx. 1.66F for a difference of a loss in temperature of 2.34F every hour. In this example the current heater won’t provide enough heat, and would take approx. 21 to 30 hours before arriving to the freezing point, considering that weather conditions are at bellow 32F for more then 24 hours. In certain regions they would experience these types of extreme temperatures for weeks and for other locations would only experience it for few hours.   

The roles of location in freeze protection

 

The correct amount of power will be always determined by location. For example, if your tank is located in Denver, Colorado and the average temperature for the winter months is bellow 32F, you would need a heater that matches or exceeds your heat loss. Using the same example as above, you would need a 350KW heater to heat 30,000 gallons of water to a rise in temperature of 4.34F/ every hour. However if your tank was located in Tennessee where they experience freezing condition for only a few hours, then using a 170KW heater would be enough because your temperature rise every hour would be 2.2F, and would be efficient enough to maintain a working temperature for up to 72 hours, before it drops bellow the freezing point.

Controls for freezing protection

Another important addition to freeze protection is controls for your heater or heaters to manage efficiently both temperature and power output. In certain cases the amperage required to run these type of heaters is very high, that’s why it’s recommend to include a step controller, and a hi limit protection system to protect your investment from failure.  

Conclusion

As a rule of thumb, when dealing with extreme winter weather it is always better to have more power behind your heater, then to come up short and turn your tank into the worlds largest Popsicle. Remember that your first line of defence is to always insulate your tank, probably the smallest investment with most benefits.

For any further details regarding freeze protection, or if you have any questions pertaining to a project you’re currently working on and need some help, please don’t hesitate to contact me.

Best Regards and keep warm 

Louis Karras

Business Development Executive

 REFENCES

Immersion Heaters

By Ilan Toledano
Tuesday Dec 6, 2011 4:54pm UTC

Immersion Heaters

Electric immersion heaters can be used for many industrial applications at various scale size. An immersion heater is a quick way to increase the target liquid or gas temperature. They are also efficient to use in the petrochemical industry. The applications of an immersion heater range from the extracted crude oil storage to the intermediate process heating in a petrochemical refinery facility.

There are different types and configurations of immersion heater that can be used in petroleum refining processes; however they all possess a common important part: the heater elements.  A heater (or heating) element is a metallic tube that is used to heat the liquid or gas via direct contact heating. Each heating element possesses a metallic sheath material tube which encloses a Nickel Chromium resistor wire surrounded by Magnesium Oxide powders. The heater element tubes are bended and annealed to maximize the heat transfer efficiency and to fit the target application such as for oil storage tank heating.

A popular selection of WATTCO™’s electric immersion heater includes the flange immersion heater. This type of electric heater consists of a heating element tube bundle that is attached to a steel flange which is used for electrical source assembly and temperature control (See Figure 1). A flange immersion heater is the best choice for heating viscous liquid container such as a large crude oil storage tank. In the refinery process, the crude oil must be heated prior the fractional distillation for product separation [1]. The pre-heating process is generally done by a large furnace at a high temperature of approximately 370 to 425°C [1]. Before sending the crude oil to the furnace unit, the oil temperature must be high enough so that its viscosity would not lower the oil processing flow rate. A delay in moving the crude oil from the tank will eventually cause the refining process to have a longer process lead time. This problem can be solved easily by using heating elements for crude oil pre-heating. The tube length and shape of the flange immersion heater are selected based on the desired application.

 

Figure 1 - Illustration of a Flange Heater for Light Oil Application

Another variation of the immersion heater is the circulation heater (in line heater) which consists of a flange heater enclosed in a cylindrical casing (Figure 2). The unique feature of this heater is the capability of heating flowing and processing liquids. A circulation heater is designed to maintain the flow rate of the incoming liquid or gas while providing the necessary heat by the heating elements. The circulation heater can be used for intermediate processes in the refinery that require a rapid and precise temperature increase of the processing liquid. The heater elements are not limited to processing oil use only but also with various liquids such as water. In addition, the circulation heater is perfect to use for waste oil heating. Waste oil is a by-product produced either during the refinery process or from the environment. This by-product oil has lost its original function and value. However, instead of disposing the waste oil into the environment, it can be re-refined and mixed to produce valuable products and save unnecessary disposal expenses [2]. Special materials can be considered for corrosive liquids heating.

 

Figure 2 - Components of a Circulation Heater

Figure 2 – Components of a Circulation Heater

Over-the-side immersion heater can be used for heating smaller size liquid tanks. An illustration of a particular shape of an over-the-side immersion heater is shown on Figure 3. A unique feature of this immersion heater is that the side wall of the liquid tank does not require an opening for heater insertion. The heater elements can be inserted to the system simply by a top inlet of the tank (such as a nozzle). The over-the-side heater is particularly efficient for precise heat control despite its smaller size. Unlike the other immersion heaters, the over-the-side heater does not require to completely empty the liquid tank before the heater removal. An example application of an over-the-side heater includes the pre-heating of liquid tank, under cold ambient environment, in order to maintain an appropriate liquid viscosity. Various over-the-side heating elements shapes are available for selection based on the target application.

 

Figure 3 – Sketch of a Heating Process with a Over-the-side Heater

 

The wide range applications of immersion heaters can provide the necessary heating for many important processes in an oil refinery facility. If you are interested in learning how the immersion heater element can provide the necessary heat to your target application, WATTCO™’s technical consultants are always available for inquiries. For more information about immersion heaters, please refer to WATTCO™’s online catalogue.

 

Reference

1.       U.S. Environmental Protection Agency. “Chapter 5: Petroleum Industry.” AP42. 5th ed. Vol. 1. Research Triangle Park, NC: U.S. Environmental Protection Agency, 1995. 5.1-7. <http://www.epa.gov/ttnchie1/ap42/ch05/final/c05s01.pdf>

2.       U.S. Department of Energy. “Used Oil Re-refining Study to Address Energy Policy Act of 2005″ National Energy Policy Act of 2005: Section 1838: Used Oil Refining Study. Office of Fossil Energy, 2006. 5.1-1 to 5.1-5.

<http://fossil.energy.gov/epact/used_oil_report.pdf>

 

Waste Oil Heaters

By Rusty James
Tuesday Nov 29, 2011 4:29pm UTC
Figure 1 - Internal & External View of the Circulation Heater

Waste Oil Heaters

Waste oil is initially believed as an excessive synthetic product that should be disposed. Waste oil is obtained from various sources, for example, from automobiles engines, industrial lubricating oils [1], vegetables waste, etc. However, by removing the oil by-product from a production process will not only cost a heavy disposal expense but the company is also subjected to an environmental cost depending on the concentration of pollutants emitted to the environment. Instead of increasing the contaminants of the city’s water supply and harm the ecosystems, why not convert the waste oil into a free heating resource? The potential of waste oil is often underestimated and this by-product could lower a large sum of unnecessary expenses for the company [2]. Burning waste oil can recycle a very useful resource and at the same time to reduce the operating costs. Applications of recycled oil include motor oil, furnace fuel, aluminium rolling oil, lubrication, etc. [3]. Those products are obtained by the re-refining process which repeats the original refining process but instead with waste oil as the input. The essential step of the refining process is to burn the waste oil by heat.

Burning oil heater does not need expensive equipment or process to achieve. The heating process can be achieved by a single step with an electric oil heater. There are various types of fuel oil heaters that can be used for waste oil burning, for example by circulation heaters (also known as in line heaters) or immersion heaters. A circulation heater is generally recommended for oil application in production industry. This type of fuel oil heater does not only increase the liquid temperature but also increase the mobility of the fluid by the circulation flow. The circulation maintains the oil viscosity so that the liquid output from the heater continuously flows to a process pipeline.

 

The uses of waste oil heaters

Figure 1 - Internal & External View of the Circulation Heater

 

A circulation fuel oil heater consists of a cylindrical casing enrobing a flange immersion heater along with two nozzles for inlet and outlet (See Figure 1). The inlet fluid enters the waste oil heater via the threaded nozzle and the liquid is then heated by the heating elements before exiting to the process pipeline that can be joined to the fuel oil heater outlet. Insulation around the steel casing is used to prevent heat loss to the ambient environment and to ensure the maximum heat transfer for the circulating oil.

The heating source generates from the heating elements tubes which are hold by a steel flange. A heating element tube consists of a Nickel Chromium resistor wire enrobed by a protective sheath material and Magnesium Oxide powders (See Figure 2). To achieve the maximum performance of the waste oil heating, the recommended sheath material would be Incoloy™. The heating process initiates from the resistor heat dissipation and the heat distributes around the surface of the heating elements. As a result, the heat is evenly distributed to the entire fuel oil heater. As the flowing waste oil enters the heater, the heating elements increase the fuel oil temperature rapidly by direct heating, and then the heated oil exits the electric oil heater outlet stream.

 

Figure 2 - Cross Sectional View of a Heater Element Tube

 

For smaller scale waste oil heating, a single flange immersion heater can be used for oil storage tank or vessel. The heating process is similar to the circulation heater, but without the use of a steel casing, the storage tank containing the oil is directly heated by the immersion heater (See Figure 3). The immersion fuel oil heater is recommended for stationary or small volume waste oil heating.

There are other types of electric waste oil heaters to consider depending on the target industry. The shapes and materials of the electric oil heaters can be customized to fit the target application. WATTCO™’s technical consultants are always available to assist the clients to select the best heater for the desired application whether the oil heating is for small or large operation.

 

Figure 3 - Sketch of a Flange Immersion Heater for an Oil Storage Tank

Figure 3 – Sketch of a Flange Immersion Heater for an Oil Storage Tank

References

1.       U.S. Environmental Protection Agency. “Chapter 1: External Combustion Sources.” Compilation of Air Pollutant Emission Factors. 5th ed. Vol. 1. Research Triangle Park, NC: U.S. Environmental Protection Agency, 1995. 1.11-1. <http://www.epa.gov/ttnchie1/ap42/ch01/final/c01s11.pdf >

2.       DHEC Office of Solid Waste Reduction and Recycling. “Used Motor Oil Recycling” DHEC’s Office of Solid Waste Reduction and Recycling FYIs. Columbia, SC. Web. Nov. 2011. <http://www.scdhec.gov/environment/lwm/recycle/pubs/used_oil_recycling.pdf >

3.       “Managing Used Oil: Advice for Small Businesses | Common Wastes & Materials | US EPA.” US Environmental Protection Agency. 28 Sept. 2011. Web. 24 Nov. 2011. <http://www.epa.gov/osw/conserve/materials/usedoil/usedoil.htm>.

Military Heaters – November 18, 2011

By Mike Lowery
Friday Nov 18, 2011 5:40pm UTC

Military heaters – Potable water supply is an importance resource for military naval ships because of its many important applications. The potable water supply from naval ships is generally used for drinking, cooking, dishwashing, laundry, hygiene and medical purposes [1]. Large volume of water must be available at all time for long period operation. The potable water must be disinfected before use in order to maintain the safety of the ship crews; this is usually done by mechanical cleaning or chemical disinfection in a water treatment plant from ashore [1]. After the disinfection process, the potable water supply can be boiled or heated to obtain hot water supply. Hot water is an important resource to achieve health safety for the navy crews. Personal and equipment hygiene requirement is very important for naval operation in order to prevent water-borne disease outbreaks [1]. For personal hygiene, hot water can be used for dishwashing, laundry, shower, etc. For equipment hygiene, the hot water can be used to clean and sterilize containers to prevent the accumulation of unwanted bacteria. Hot water is usually obtained by applying electric heating on the potable water supply stored in a large tank (See Figure 1).

 

Figure 1 - Cross Sectional View of a Naval Ship with a Hot Water System

 

The pre-heated water supply temperature will eventually drop if there is no heating source on the tank, therefore the water tank should be kept warm during the entire marine operation. Since the water supply is normally stored in a water tank, the heating process can be done by simply using an immersion heater to maintain the warming temperature of the liquid. An immersion heater is an industrial electric heater which is designed for heating various liquid and gas of wide temperature and pressure range. The main advantage of immersion heaters is the minimal space requirement for the heating process. The heating process is done by one or multiple bundled heating elements.

A heating element tube consists of a Nickel Chromium resistor wire enclosed by a protective sheath material and Magnesium Oxide powders (See Figure 2). The sheath material selection is based on the desired target application. For example, Incoloy™ or copper is generally recommended for hot water application and stainless steel for corrosive solutions. The heater elements will warm the target liquid by direct contact heating. The heating process starts from the heat dissipation from the resistor wire and the heat distributes around the surface of the heating elements which result the liquid heating of the entire tank.

 

Figure 2 - Cross Sectional View of a Heater Element Tube

Among several types of immersion heater, the flange type heater has the best performance for hot water application. This immersion heater consists of a steel flange bundled with multiple heater elements which is mounted on the water storage tank wall (See Figure 1). A hot water temperature of 120 to 135°F is generally suitable for the marine operation [2]. The flange heater elements are able to achieve this temperature range under short period of time. In addition, a digital temperature controller can also be installed to maintain the desired temperature of the hot water at any time.

 

Figure 3 – Flange Heater Manufactured by WATTCO™

 

In marine operations, hot water is primarily consumed for hygiene, cooking and drinking. However, the hot potable water demand may increase during times of emergency. An emergency hot water unit can be utilized when hot water becomes an absolute requirement during urgent period such as for medical purposes or during events of unexpected hot water shortage. Flange heaters can be used to heat the emergency water container during event of the primary hot water unit failure. A breakdown of a hot water system generally takes a long period to repair, mainly due to the maintenance and disinfection procedure. Therefore it is recommended to have an extra hot water system installed and ready for the unexpected emergency period.

According to Department of the Navy of United States, the minimum potable water requirement for the naval ship crews is 2 gallons per man per day for cooking and drinking purposes [1]. Therefore the total volume of water supply could go as high as 100,000 gallons or more for a single naval ship depending on the number of staffs. However, regardless of the required tank size, WATTCO™ can provide the necessary heating elements for the desired hot water application. The selection and sizing of the flange and heater elements depends entirely on the target tank volume and size. Therefore it is recommended to consult WATTCO™’s supporting technicians in order to ensure the compatibility of the heater.

 

 

 

 

 

Reference

1.        USA. Department of the Navy. Bureau of Medicine and Surgery. Water Supply Afloat. By D.C Arthur. 7th ed. Washington, 2005. Http://www.med.navy.mil. Department of Defense (DOD), 2005. Web. 17 Nov. 2011. <http://www.med.navy.mil/directives/Pub/5010-6.pdf>.

2.        USA. Oak Ridge National Laboratory. Lockheed Martin Energy Research Corp. Retrofit Guide for Military Family Housing: Energy Efficient Weatherization and Improvements. By Wisconsin Energy Conservation Corporation, Dec. 1996, p.8-9. Web. 17 Nov. 2011. <http://www.wbdg.org/ccb/DOE/TECH/retrofit.pdf>.