The DIFHEMI is an ideal solution for the direct heating of any type of fluid among dozens of applications in the field of thermal engineering. Common applications include thermal fluid heating for molding tools, thermal traces, chemical reactors, oils or chemical storage tanks, tunnels and presses for vulcanisation of rubber. It is also well suited for the direct heating of corrosive solutions (acid and basic) and easily cracking oils and ultra-viscous oils. Direct heating of any type of gas (e.g. propane, butane and natural gas) and any type of flammable fluid (e.g. gasoline, ethanol, aviation kerosene, industrial solvents) is also a popular application for this new technology. In short, the system is suitable for use in all industrial processes that require fluids to be heated either directly or indirectly.
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Questions & Answers about DIFHEMI
What are DIFHEMI inductive fluid heaters?
DIFHEMI inductive fluid heaters (DIFHEMI is an acronym of ‘direct fluid heating by electromagnetic induction’) are of leading-edge innovative technology which is the sole property of Brascoelma; they belong to a new generation of fluid heaters which are unparalleled worldwide. They are currently the most-efficient equipment and heat any type of fluid, directly or indirectly, liquid or gaseous, at the desired temperature, flow rate and pressure. They utilise electromagnetic induction to generate heat and do not require electrical resistances of any kind, nor the use of fossil fuels. DIFHEMI inductive fluid heaters have permitted realising heating projects which would otherwise be nonviable, and since 1983 over 300 companies have used them. They have been found to be more advantageous than systems utilising resistance heating, fuel oil or natural gas, due principally to the inefficiency inherent in these latter systems of heat generation because of their requirement for constant maintenance. Precise working-temperature control, low cost, practically maintenance-free and heating any type of fluid at any temperature and pressure are some of the advantages offered by the DIFHEMI inductive electrothermal generators (or inductive fluid heaters) manufactured by Brascoelma.
Do DIFHEMI heaters contain eletrical resistences?
No, unlike conventional heaters DIFHEMI heaters do not contain electrical resistances. They utilise the principle of electromagnetic induction as the source of heat.
In DIFHEMI inductive heaters, heat is generated in the walls of the stainless-steel tubes which surround the magnetic nucleus in coil form, in a similar manner to the windings of a network transformer, and they are derived from transformer principles. The stainlesssteel tubes, heated by the Joule magnetic-induction effect, transfer all their heat to the fluids flowing within them; they do not have electrical resistances and they have a high energy efficiency exceeding 98%. From the thermodynamic and Exergetic* points of view, DIFHEMI inductive heating has been shown in practice to be greatly superior, by up to 30%, when compared with traditional heating systems.
Do short-circuits occur or does the fluid penetrate the resistences resulting in combustion of the fluid during heating, this occur in DIFHEMI?
No! Short-circuits will never occur in DIFHEMI inductive electrical heaters, nor will liquid penetration and nor will liquids be combusted while being heated. DIFHEMI
equipment operates at ZERO voltage in the coiled tubes of the heating system, offering greater safety in fluid heating, even in the case of conductive fluids such as acids or bases. There is total safety in operation, additional care not being required by virtue of the physical separation between the tubes of the coils of the heating section and the electric mains. The DIFHEMI inductive heater project was conceived with the objective of heating highly-flammable or explosive gases or fuels directly, even when operating in hazardous areas, such as petroleum platforms. The fluid circulates within stainless-steel tubes welded and tested to a pressure of up to 300 bar (4000 psi); they are consequently free from the risk of penetration. These characteristics, allied with a specific design for each client and the unique properties of durability of stainless steel tubes, make the DIFHEMI inductive fluid-heating equipment practically maintenancefree, no heating-element change being required during its working life. DIFHEMI inductive fluid heaters have permitted the realisation of heating projects which would be 2 non-viable employing other electrical means. Brascoelma’s welding procedures and Brazilian welder certificates for welding stainless steel and carbon steel are signed by a welding inspector qualified to Petrobras/SEQUI and FBTS level 2 in Brazil.
Why do DIFHEMI heaters run at zero voltage, and why is their electrothermal performance so excellent?
The concept may be summarised as being the application of voltage to the primary winding, producing heat in the tubular bundle of the secondary coil through the Joule effect because the terminals of the coil are short-circuited. Consequently, all the energy applied to the primary source is converted into thermal energy in the secondary coil, through which the fluid circulates, a fact leading to a very high exergetic efficiency of at least 98%.
What advantages do DIFHEMI heaters have over the use of electrial resistances?
The series of advantages of inductive heaters compared with electrical resistances may be defined as follows:
» Tubular format of the heating element. » High coefficient of convective heat-exchange, Exergetic* efficiency; this does not occur with the use of electrical resistances.
» Greater heat-exchange efficiency due to the low temperature of the heating element (stainless-steel-tubing wall).
» The fluid flows within the tubing and the heat is transmitted by magnetic induction, differing from the case with electrical resistances where the fluid flows externally to the resistances.
» Durability of DIFHEMI heaters’ stainless-steel tubing when compared with electrical resistances.
» Elimination of the problem of cracking, hot-spot and combustion of some fluids (fuel oils, vegetable oils, thermal fluids, etc), as occurs with the use of electrical resistances.
» Heating-element replacement does not arise, permitting continuous operation without downtime and without the risk of short-circuit or explosion, as in the case of electrical resistances.
» Economic in terms of maintenance and electrical-energy consumption (saving of 10 to 30%, depending on the process).
What is Exergetic* efficiency?
From point of view of Exergy*, the efficiency calculation takes into account the thermodynamic conditions of the environment external to the unit in which the overall
process takes place, or to the component in which a specific process is carried out. It is a novel efficiency calculation with the purpose of establishing the ratio between the loss in capacity of conversion of the quantity of energy utilised for the obtainment of the desired effect and the loss of capacity of conversion of the quantity of energy required to do so. The capacity of conversion of a given amount of energy is measured in relation to the external environment and is referred to each of its forms. This capacity of conversion is called Exergy*. The advantage in utilising Exergy* is that it brings the various forms of energy to a single basis for comparison, because the Exergy* accompanying a process has the same capacity of conversion in respect of any of them, differing from energy. That is to say, in any process the final Exergy* may be compared with the initial Exergy*. This is the basic principle of the Exegetic analysis employed in DIFHEMI heater-efficiency calculations. Consequently, Exegetic analysis is appropriate in so far as it leads to more precise results, providing conditions for improved decisionmaking in respect of changes to the designs or operating conditions of the units. It also facilitates undertaking an Exergetic* thermoeconomic analysis, identifying different options of qualities of energy and processes, leading to cost reductions.
Technically EXERGY*, or maximum work content, may be defined as ‘the maximum amount of work obtained by a system where the flow of a substance is conducted from an initial to an end state, and can be compared to Gibbs free energy’, where G = U + PV - TS, it also being a measure of the degree of allocation between the system and its environment and the standard state. Energy is a property of a system according to the first law of thermodynamics and cannot be destroyed (conservation of energy); in each conversion part is lost, that is to say the part not used to do work. According to Rant, Exergy* is the portion of energy that can be converted into another type of energy, e.g. conversion into heat or work. According variously to Rant and Kotas, ENERGY = EXERGY + ANERGY, Rant proposing the word ANERGY to refer to the portion of energy unused.
Consequently, in accordance with the foregoing equation, it may be said that energy is the sum of the portions of all the energy used (exergy) plus the anergy (the portion that cannot be used). According to Kotas, this measure refers to the maximum work performed by a system to attain equilibrium in its interaction with the environment.
How does heating take place?
Employing the principle of magnetic induction, heat is generated in the walls of the coil of stainless-steel tubes in DIFHEMI induction fluid heaters. The fluid circulating through the tubes removes the heat which is utilised in the heating process. The heating process is extremely easy and practical. The fluid to be heated coming from the pump enters the inlet tube and passes through the stainless-steel tubular bundle around the nucleuses, as in a transformer. The heat generated heats the fluid which then exits through the outlet tube. The high heat-exchange coefficient, characteristic of inductive heaters, is reflected in a lower film-temperature, i.e. the difference in temperature between the fluid and the tube wall is always very small. This in turn means durability and economy in a heating system, particularly of mineral or synthetic thermal oils. The extremely-low thermal inertia of inductive heaters, even in large-scale units, permits controlling the temperature of the fluid with a precision unachievable by any other existing type of fluid heater. The induction heating system offers the user an economic process with very-precise control and rapid response to temperature variations. The high heat-exchange efficiency between the wall of the tubes and the fluid flowing through them signifies that an inductive heater is the most electrically-efficient electrical machine in existence.
What certificates do DIFHEMI heaters possess and with international technical codes and standards to they conform?
DIFHEMI inductive fluid heaters possess the following certificates and operate in conformity with the standards below:
ISO 9001:2000 certificates from NET (no. IT-23905) and RINA (no. 6518/02/IS) (from Brazil).
SGS/CEPEL/IAF/UL/IEx/Petrobras’ Certificate of Registration and Record Classification (Brazilian Specifications)
ASME: American Society of Mechanical Engineers
ANSI: American National Standards Institute
ISO: International Organization for Standardization 4
ASTM: American Society for Testing and Materials
IEEE: Institute of Electrical and Electronic Engineers
NEMNational Electrical Manufacturers Association
IEC: International Electrotechnical Commission
AISI: American Iron and Steel Institute
OSHOccupational Safety and Health Act.
How long is a DIFHEMI inductive heater's working life?
From our practical experience, the working life of a DIFHEMI inductive heater is much longer than that of an electrical-resistance or fossil-fuel-burning heater. DIFHEMIs are based on the transformer concept. Their durability, as in the case of transformers, depends exclusively on care in operation, but also on the type of fluid, and the quality characteristics desired by a client in the initial design. We have had DIFHEMIs in use in the market for over 20 years without any maintenance. To achieve this, as with power transformers, we always advise taking normal care during operation.
What types of fluid can DIFHEMIs heat?
DIFHEMIs can heat any type of fluid. The industrial applications of DIFHEMI inductive heaters cover all industrial processes involving heating fluids directly or indirectly. Among dozens of applications, the most common are listed below. Heating thermal fluids for heating:
• mould tools.
• heat traces.
• chemical reactors.
• oil or chemical-product storage-tanks.
• rubber vulcanisation tunnels and presses.
• corrosive solutions.
Direct heating of easily-cracked ultraviscous oils, such as:
• Fuel oils of Brazilian types 1A to 9A (UN no. 3082).
• Pitch and PACs.
• Vegetable oils, etc.
Direct heating of any type of gas, such as:
• Ambient air for furnaces (ovens), driers, etc.
• Compressed air.
• Natural gas.
• Hydrogen, oxygen, nitrogen, argon, etc.
Direct heating of any type of flammable liquid, such as:
• Aviation fuel.
• Industrial solvents.
• Alcohols in general, etc.
» Heating surface-treatment baths (pickling, washing, etc).
» Chemical-product distillation and concentration.
» Pharmaceutical processes, ultrapure water.
» Pasteurisation of liquids, juices, milk, etc.
» Manufacture of resins and pigments.
» Deodorisation of food-grade oils in general.
» Biodiesel production.
» Manufacture of fibres, polyester, etc.
» Direct application in cement, glass, aluminium production, mining processes, iron pelletising, etc.
» Direct heating of highly-corrosive or high-purity fluids.
» Operations in classified and hazardous areas.
» Recycling (used) automotive oils in oil-rerefining plants.
» Heating saturated steam to generate superheated steam.
And for other direct-heating purposes, such as:
· Hot water for buildings, plants, laundries and car washes.
· Thermal fluids.
· Steam generation or steam superheating.
· Ordinary and pure water, and ultrapure liquids.
· Pasteurisation of wastewater (sewage, industrial).
· Gas drying in general (nitrogen, hydrogen, ambient air and pressurised air, etc).
· Drying transformer oils.
What are the advantages of DIFHEMIs in comparison with other fluid-heating systems?
A group of engineers in the heating field declared DIFHEMI inductive fluid heaters to be one of the most-important ideas developed in the decade of the 80s. Today they are an incontestable reality, having demonstrated their versatility in heating any type of fluid with a proven overall efficiency of 98%. This makes inductive fluid heaters one of the most efficient electrical machines developed, verifiably approved and utilised at more than 300 clients, with over 1000 units sold.
Due to their innumerable unbeatable applications in the field of electrothermy, the use of inductive fluid heaters has resulted in immediate savings in processes using electrical energy, when compared with energy from fossil-fuel combustion or even when compared with the use of electrical resistances. Some advantages are described below.
» Total safety in operation, additional care not being required by virtue of the physical separation between the heater and the electric mains.
» The system runs dry, being cooled naturally.
» The system does not generate flames or sparks and can directly heat highlyflammable gases and fuels.
» The entire heating element operates at zero voltage, offering greater safety in heating any type of fluid, even conductive fluids.
» Inductive heaters, DIFHEMI, offer improved efficiency when compared with heating systems employing electrical resistances, fossil fuels, or even in steam generation.
» Their tubular heating-elements permit highly-efficient heat exchange with high heattransmission coefficients and, consequently, with low fluid/wall temperature differences.
» The high heat-exchange efficiency between the tubes’ wall and the fluid flowing through them signifies that inductive heaters are the most electrically-efficient electrical machines in existence.
» The high heat-exchange coefficient, characteristic of inductive heaters, DIFHEMI, is reflected in a (wall) film temperature which is always low, i.e. the temperature difference between the fluid and the tube wall is always very small, this in turn means durability and economy in mineral or synthetic thermal-oil heating systems.
» The extremely-low thermal inertia of inductive heaters, DIFHEMI, even in large-scale units, permits temperature control of the fluid with a precision unachievable by any other type of existing fluid heater.
» The system of heating by induction permits users to obtain an economic process with very-precise control and rapid response to temperature variations.
» Among their innumerable possible applications DIFHEMI inductive heaters have been shown to be absolutely the most-efficient and safest equipment for heating ultraviscous fuels, petroleum, pitch, and rubber-production tunnels.
» Because they do not contain moving parts or electrical resistances, their construction signifies that they are practically maintenance-free. Conventional systems, with electrical resistances and steam boilers, lead to high maintenance costs together with downtime.
» They are limited solely by the type of fluid and are capable of operating at high temperatures and pressures.
· Modular application
» Inductive heaters are the most-compact units in comparison with other fluid-heating systems, leading to a saving of physical space together with great ease of installation.
» Their characteristics permit modularity in application, simplifying and/or taking advantage of an existing layout, and the modularity may be in terms of production
sector or each specific unit.
Can DIFHEMI heat water and also function as steam generators?
Yes, indeed, water being a fluid. DIFHEMIs can both heat residential domestic water and produce steam and replace boilers with any type of heat source, always provided that the cost/benefit ratio so permits. They can also produce high-temperature superheated steam downstream from any type of boiler. Superheated-steam production by DIFHEMIs it is much less expensive than by means of other processes. A further important application of DIFHEMIs is in heating pure and ultrapure water for pharmaceutical or industrial purposes requiring this type of water.
Are DIFHEMI heaters' tubes protected from aggressive solutions and pure water at high temperatures?
Yes. The internal circuit, i.e. the tubes through which pure water or any other solution (acid or alkaline) flows are internally coated with materials, of Teflon or similar, resistant to these fluids. The decision to provide specific protective materials is generally taken by our engineering department during the design phase, unless a client requires the stainless-steel tubes to be coated, or otherwise, with protective layers or, alternatively, that other materials be used. They are capable of heating any aggressive acid or alkaline solution and are widely utilised for thermochemical processes.
What are the advantages of using DIFHEMIs to procedure hot water?
Depending on the case in point, and where electrical resistances and fuel combustion are not indicated, they are employed in e.g. residential buildings, swimming pools, laundries, car washes, food and pharmaceutical industries. With the objective of cost reduction, and depending on the power, DIFHEMI heaters can be coupled to wind turbines and/or solar panels.
What advantages do DIFHEMI heaters offer in steam production compared with fossil-fuel boilers or those with electrical resistances?
DIFHEMI inductive heaters offer the best conditions for the generation of steam without the pollutant emissions from heat-generating boilers based on fossil-fuel combustion.
Employing DIFHEMIs to directly heat the water, entering the system at ambient temperature through the inlet and exiting in the form of steam at the desired temperature and pressure through the outlet, increases productivity and reduces other operating costs, together with those of implementation. There are innumerable advantages in using DIFHEMIs and some of the most important are mentioned below.
· As a result of the Kyoto protocol**, steam boilers heated by combusting fossil fuels, gas, oil, pitch, coal, etc..., generate pollutants whose particulates, such as dust (heavy and alkaline metal oxides), and the gaseous materials CO, NOx, VOC, SO2 and PCDD/F require specific filters, these on occasion being more expensive than the boilers themselves (this without taking into account that the majority of them are carcinogenic).
(**) 1997 Kyoto Protocol to control the production of harmful gases, such as dioxins, furans, NOx, VOC, PCDD/F 1/96/CE and CO/CO2, legitimising an economically-viable mechanism for large international polluters to reduce GHG emissions, inventorying emissions by means of CER credits issued where there is a demonstrable reduction in the emission of gases causing global warming; these certificates are issued by regulatory environmental protection agencies. Companies which achieve a reduction in the emission of greenhouse gases may profit from the sale of these carbon credits.
· DIFHEMI heaters do not require filters because they do not burn any fuel.
· Because of the hazard of explosion it is a requirement that steam boilers heated by fossil fuels be installed in an exclusive boiler house or cabin, the plant of which must satisfy government regulations in the environmental, fire-safety, Ministry of Employment, municipal and other fields (without even considering the time required for this).
· DIFHEMI heaters are exempt and do not require any of these governmental approvals, nor do they require to be specifically registered with any public body; in addition to these savings, companies may also generate profits by selling the carbon credits to polluting companies.
· Boilers require an extensive pipework network, greatly increasing the cost of investment and maintenance due to the fact that they have to be installed remotely from the point requiring the heat or the production machinery (the boiler house must be isolated from other buildings).
· DIFHEMI heaters do not require a pipework network because they can be installed very close to the point where the steam is required.
· Boilers require constant monitoring because of their hazardousness and have very high operating costs with diverse outgoings such as those below arising from:
» administrative workforce for the constant issue of operating reports.
» supervision by engineers, production and safety technicians.
» the purchase of diverse consumables and parts for maintenance.
» many outgoings in terms of maintenance and purchase of accessories.
» outgoings in terms of feed-water treatment.
· Due to their design DIFHEMI heaters do not present an explosion hazard as in the case of boilers. 8
· DIFHEMI heaters do not require any specific monitoring because they operate automatically, all parameters being PC-controlled.
· DIFHEMI heaters have almost-immediately-available heat once energised due to their extremely-low thermal inertia, eliminating the long periods of heating required for boilers to attain their operating temperature. On connecting the water to the inlet tube at any desired temperature and pressure steam is immediately observed at the outlet tube, and they can additionally produce superheated steam.
· DIFHEMI heaters provide overall energy savings due to their high thermal efficiency of 98%.
· DIFHEMI heaters eliminate all costs of boiler maintenance, installation and associated contracts.
· DIFHEMI heaters eliminate water treatment and economise on water consumption, less condensate being produced.
· DIFHEMI heaters do not generate noise when producing steam; they are totally silent.
· DIFHEMI heaters are easy to install, they come with a supporting base which solely requires bolting to the ground and their connection to the short steamtransportation pipework is extremely easy. They have one of the lowest installation costs for heaters in the world.
· DIFHEMI heaters save space in your factory due to their compact construction.
· DIFHEMI heaters do not require a maintenance or operating logbook, as is the case with boilers. It is not a matter of a pressure vessel. · Because they are installed very close to the point of use there are no steam leaks (losses) in the DIFHEMI heater pipework network.
· DIFHEMI heaters do not require the use of the additives employed to treat fuel oil as in the case of in boilers.
· DIFHEMI heaters offer fluid-temperature precision and uniformity during the entire process because the temperature in the system is maintained constant and regulated.
· The working pressure of DIFHEMI heaters is equivalent to the inlet pump pressure.
· DIFHEMI heaters offer total safety for the operator, for the factory itself, and for the entire process.
· DIFHEMI heaters have the advantage of thermal savings through the elimination of steam-transportation pipework.
· DIFHEMI heaters do not require maintenance contracts for either the unit itself, oil-storage tanks, hydraulic system, fuel-injector nozzles, pressure tank or pressure adjustments to Brazilian standard NR13, nor do they require boiler-operator shifts covering the 24 hours.
· Against a client order, DIFHEMI heaters may be used downstream of the steam outlet from other types of boiler to obtain superheated steam.
· The majority of these advantages are also valid in comparison with boilers and electrical resistances.
In addition to water, what other fluids can be heated by DIFHEMIs?
As noted above, DIFHEMIs can heat any type of fluid, liquid or gaseous. One of the major applications is in heating thermal oil used for any type of activity where heat transfer is necessary to heat another fluid by means of heat exchangers. The fact of the thermal oil being heated by a DIFHEMI brings innumerable advantages, such as those referred to above in the heating of other fluids, when compared with electrical 9 resistances. Due to their advanced design DIFHEMIs do not cause surface microcombustion of the thermal oil with premature carbonisation and hot-spots, as occurs when electrical resistances or other sources of heat are used, this leading to an increase in the consumption of thermal oil and lowering its quality. The use of a DIFHEMI extends the working life of the thermal oil, maintaining its properties constant for a much-longer period.
Can any type of oil be heated, or solely thermal oil?
As noted above, DIFHEMIs are capable of heating any fluid and, consequently, any type of oil, such as food-grade oils and animal fat from any source, being principally recommended for deodorising any type of oil. Please see the possible applications of DIFHEMI heaters in the answer to the previous question.
Can I heat thermal oil directly, avoiding passing it through a heat exchanger?
Certainly. For diverse reasons, in some cases heating the final fluid must be carried out through the process referred to as ‘indirect heating’, passing it through a heat exchanger. However, in the majority of cases we inform our clients that, whenever possible, they should heat the final fluid directly by the DIFHEMI, this being referred to as ‘direct heating’, because this will lead to a great saving in energy and space, together with increased safety, without mentioning maintaining the quality of the thermal oil.
Can orange juice, milk or other products be pasteurised directly, without heat exchanges?
Absolutely. Our engineering department will recommend the use of special stainlesssteel tubes for food-grade purposes for DIFHEMIs carrying-out pasteurisation. You can pasteurise any food-grade liquid, juice, etc..., even milk. If required, we can also provide the pasteurisation assembly with the cooling phase.
What tests are DIFHEMI heaters subjected to?
In order to ensure the quality of DIFHEMI inductive fluid heaters, and their perfect operation following installation, Brascoelma-developed tests, based on Brazilian ABNT standards, are carried out in our own laboratory.
The principal tests are:
» Penetrant liquid tests on all stainless-steel tubing welds during the manufacturing phase, Section III, Volume 3, JIS Z 2343. » Hydrostatic test at 1.5 x working pressure.
» X-ray of stainless-steel welds (at the client’s request).
» Operating test with low voltage and power applied to the inductive heater.
» Measurement of the power factor of the unit.
» Measurement of the final power of the heater.
» Measurement of the electrical resistance of the inductive windings, and calculation of losses to determine their electrical performance.
» Megohmmeter measurement of insulation resistance between the inductors and the earthed tubular coils.
» Application of 2500 volts for one minute between the inductive winding and the heating coil plus ground (for voltages of up to 690 volts).
» Functional tests of the electronic panel and thyristor triggering.
» Visual and dimensional inspection. Brascoelma’s welding procedures and Brazilian welder certificates for welding stainless steel and carbon steel are signed by a welding inspector qualified to Petrobras/SEQUI and FBTS level 2 in Brazil.
In addition, against an order from the client, units may be subjected to tests for utilisation in classified areas with a certificate issued by a competent certifying body and validated by INMETRO (Brazil). Brascoelma warrants its product for two years from manufacture.