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An electric boiler is a device that uses electrical energy to boil water instead of fossil fuels used in traditional gas or oil boilers. [1]
| | This article needs additional citations for verification .(August 2017) |
An electric boiler is a device that uses electrical energy to boil water instead of fossil fuels used in traditional gas or oil boilers. [1]
There are different types of electric boilers. These three classifications are: classic, ionic, or induction. These classifications are determined based on the boiler's power output, energy performance, model type, energy consumption, and energy efficiency. [2]
In a residential setting, an electric boiler is often used as a backup to a house's heating system. During the colder months, heating and hot water is used more frequently. This type of boiler will provide additional heating and hot water to a home. [3]
Some types of boilers aren't used for heating, but for other purposes. A boiler could be used as a household appliance or to produce steam for an industry.
An electric steam boiler is intended to produce steam for process industry or other uses, such as drying, heat treating, and others. These are generally permanently installed systems with connections to a water supply and piping to transport product steam to the point of use. In places where electric power is relatively low cost compared to fossil fuels, it may be economically practical to use an electric boiler for steam central heating. For example, in Winnipeg, Canada, during the Second World War, large central electric steam boilers were used for a district heating system, using surplus hydroelectric power. The intent was to conserve coal fuel for more critical wartime needs.
Electric boilers may rely on immersion heater resistance heating elements to heat water, or may use electric current passing directly through the water as an electrode boiler. [4]
A boiler will have five key parts: a burner, combustion chamber, heat exchanger, exhaust stack, and controls. A burner gives off heat that is necessary to heat up the water. A combustion chamber holds the burners and is in charge of the combustion process. A heat exchanger brings the heat from the burner to the water. Its job is to bring heat to the water without having contact with the water, similar to boiling water in a pot. An exhaust stack takes the hot gases and transfers them away from the boiler. Boiler controls are there to make sure the hot water or steam is produced in a safe way. [5]
In addition to these five key parts, a boiler also has a firebox, refractory, and return lines. A firebox contains the flame, created from the fuel and air. A refractory or refractory materials, is used to make sure the fire stays contained by closing any gaps in the firebox. Return lines are used when the water is cooled down. When the water is cooled, the return lines bring the water back to reheat. [6]
Even the tabletop appliance will have a control switch or at least an over temperature cut out to prevent fire if the appliance is started with no water in it. Larger installations have more elaborate controls to ensure that sufficient water supply is available to prevent burn out of the heating elements. These may include interlocks, pressure switches or other measures. [4]
A boiler is a pressure vessel and industrial boilers are constructed, operated and inspected in accordance with local regulations to reduce the risk of explosion. For example, permanently installed pressure relief valves will operate if a control malfunction results in excessive pressure in the boiler.
Normally resistance heating elements are insulated from the water going through the boiler; sensitive ground fault leakage current detection may be installed to alarm or shut off power if an insulation failure is detected. Electrode boilers put the water supply in direct contact with the electrical supply; current collectors or other features may be provided in piping to prevent dangerous electrical hazards on connected piping.
Any dissolved minerals in the water will be concentrated by the evaporation and will tend to form a scale coating heating surfaces. Even potable water may contain enough minerals to eventually clog or scale a boiler. Household appliances can be cleaned readily, but permanent boiler installations require control of make-up water supply chemistry to reduce scaling.
Electric heating is generally highly efficient; since there is no stream of waste combustion gases emitting from the boiler, nearly all the purchased energy appears in the product hot water or steam in useful form. This high efficiency even in small sizes partly offsets the generally higher cost of electric energy compared to fossil fuels. An electric boiler can be placed in operation quickly, as there is no furnace to reach high temperatures. [4] Environmental impact is displaced to the source of the grid electricity; however, if fossil fuel is being consumed to make electricity, overall efficiency will be lower than direct use of the fuel.
Operationally, an electric boiler is a convenient process unit that is easy to control and that requires no space for fuel storage nor for an exhaust gas stack. There is no blower for combustion air and only minimal pumps required for operation, so the boiler is quiet. [4]
A boiler is a closed vessel in which fluid is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation, cooking, and sanitation.
A furnace, referred to as a heater or boiler in British English, is an appliance used to generate heat for all or part of a building. Furnaces are mostly used as a major component of a central heating system. Furnaces are permanently installed to provide heat to an interior space through intermediary fluid movement, which may be air, steam, or hot water. Heating appliances that use steam or hot water as the fluid are normally referred to as a residential steam boilers or residential hot water boilers. The most common fuel source for modern furnaces in North America and much of Europe is natural gas; other common fuel sources include LPG, fuel oil, wood and in rare cases coal. In some areas electrical resistance heating is used, especially where the cost of electricity is low or the primary purpose is for air conditioning. Modern high-efficiency furnaces can be up to 98% efficient and operate without a chimney, with a typical gas furnace being about 80% efficient. Waste gas and heat are mechanically ventilated through either metal flue pipes or polyvinyl chloride (PVC) pipes that can be vented through the side or roof of the structure. Fuel efficiency in a gas furnace is measured in AFUE.
A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney effect. The space inside a chimney is called the flue. Chimneys are adjacent to large industrial refineries, fossil fuel combustion facilities or part of buildings, steam locomotives and ships.
Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated to steam have many uses.
A combined cycle power plant is an assembly of heat engines that work in tandem from the same source of heat, converting it into mechanical energy. On land, when used to make electricity the most common type is called a combined cycle gas turbine (CCGT) plant, which is a kind of gas-fired power plant. The same principle is also used for marine propulsion, where it is called a combined gas and steam (COGAS) plant. Combining two or more thermodynamic cycles improves overall efficiency, which reduces fuel costs.
Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time.
A central heating system provides warmth to a number of spaces within a building from one main source of heat.
A fire-tube boiler is a type of boiler invented in 1828 by Mark Seguin, in which hot gases pass from a fire through one or more tubes running through a sealed container of water. The heat of the gases is transferred through the walls of the tubes by thermal conduction, heating the water and ultimately creating steam.
A high pressure watertube boiler is a type of boiler in which water circulates in tubes heated externally by fire. Fuel is burned inside the furnace, creating hot gas which boils water in the steam-generating tubes. In smaller boilers, additional generating tubes are separate in the furnace, while larger utility boilers rely on the water-filled tubes that make up the walls of the furnace to generate steam.
In a steam engine, the firebox is the area where the fuel is burned, producing heat to boil the water in the boiler. Most are somewhat box-shaped, hence the name. The hot gases generated in the firebox are pulled through a rack of tubes running through the boiler.
A heat recovery steam generator (HRSG) is an energy recovery heat exchanger that recovers heat from a hot gas stream, such as a combustion turbine or other waste gas stream. It produces steam that can be used in a process (cogeneration) or used to drive a steam turbine.
A thermal power station, also known as a thermal power plant, is a type of power station in which the heat energy generated from various fuel sources is converted to electrical energy. The heat from the source is converted into mechanical energy using a thermodynamic power cycle. The most common cycle involves a working fluid heated and boiled under high pressure in a pressure vessel to produce high-pressure steam. This high pressure-steam is then directed to a turbine, where it rotates the turbine's blades. The rotating turbine is mechanically connected to an electric generator which converts rotary motion into electricity. Fuels such as natural gas or oil can also be burnt directly in gas turbines, skipping the steam generation step. These plants can be of the open cycle or the more efficient combined cycle type.
A pellet stove is a stove that burns compressed wood or biomass pellets to create a source of heat for residential and sometimes industrial spaces. By steadily feeding fuel from a storage container (hopper) into a burn pot area, it produces a constant flame that requires little to no physical adjustments. Today's central heating systems operated with wood pellets as a renewable energy source can reach an efficiency factor of more than 90%.
Condensing boilers are water heaters typically used for heating systems that are fueled by gas or oil. When operated in the correct circumstances, a heating system can achieve high efficiency by condensing water vapour found in the exhaust gases in a heat exchanger to preheat the circulating water. This recovers the latent heat of vaporisation, which would otherwise have been wasted. The condensate is sent to a drain. In many countries, the use of condensing boilers is compulsory or encouraged with financial incentives.
Economizers, or economisers (UK), are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid. The term economizer is used for other purposes as well. Boiler, power plant, heating, refrigeration, ventilating, and air conditioning (HVAC) may all use economizers. In simple terms, an economizer is a heat exchanger.
Forced-air gas heating systems are used in central air heating/cooling systems for houses. Sometimes the system is referred to as "forced hot air".
A boiler or steam generator is a device used to create steam by applying heat energy to water. Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure but, at pressures above this, it is more usual to speak of a steam generator.
A wood-burning stove is a heating or cooking appliance capable of burning wood fuel, often called solid fuel, and wood-derived biomass fuel, such as sawdust bricks. Generally the appliance consists of a solid metal closed firebox, often lined by fire brick, and one or more air controls. The first wood-burning stove was patented in Strasbourg in 1557. This was two centuries before the Industrial Revolution, so iron was still prohibitively expensive. The first wood-burning stoves were high-end consumer items and only gradually became used widely.
Tankless water heaters — also called instantaneous, continuous flow, inline, flash, on-demand, or instant-on water heaters — are water heaters that instantly heat water as it flows through the device, and do not retain any water internally except for what is in the heat exchanger coil unless the unit is equipped with an internal buffer tank. Copper heat exchangers are preferred in these units because of their high thermal conductivity and ease of fabrication. However, copper heat exchangers are more susceptible to scale buildup than stainless steel heat exchangers.
An industrial furnace, also known as a direct heater or a direct fired heater, is a device used to provide heat for an industrial process, typically higher than 400 degrees Celsius. They are used to provide heat for a process or can serve as reactor which provides heats of reaction. Furnace designs vary as to its function, heating duty, type of fuel and method of introducing combustion air. Heat is generated by an industrial furnace by mixing fuel with air or oxygen, or from electrical energy. The residual heat will exit the furnace as flue gas. These are designed as per international codes and standards the most common of which are ISO 13705 / American Petroleum Institute (API) Standard 560. Types of industrial furnaces include batch ovens, metallurgical furnaces, vacuum furnaces, and solar furnaces. Industrial furnaces are used in applications such as chemical reactions, cremation, oil refining, and glasswork.