Chimney - WikiHQ

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.

In the United States, the term smokestack industry refers to the environmental impacts of burning fossil fuels by industrial society, including the electric industry during its earliest history. The term smokestack (colloquially, stack) is also used when referring to locomotive chimneys or ship chimneys, and the term funnel can also be used.

The height of a chimney influences its ability to transfer flue gases to the external environment via stack effect. Additionally, the dispersion of pollutants at higher altitudes can reduce their impact on the immediate surroundings. The dispersion of pollutants over a greater area can reduce their concentrations and facilitate compliance with regulatory limits.

History

Industrial chimney use dates to the Romans, who drew smoke from their bakeries with tubes embedded in the walls. However, domestic chimneys first appeared in large dwellings in northern Europe in the 12th century. The earliest surviving example of an English chimney is at the keep of Conisbrough Castle in Yorkshire, which dates from 1185 AD, but they did not become common in houses until the 16th and 17th centuries. Smoke hoods were an early method of collecting the smoke into a chimney. These were typically much wider than modern chimneys and started relatively high above the fire, meaning more heat could escape into the room. Because the air going up the shaft was cooler, these could be made of less fireproof materials. Another step in the development of chimneys was the use of built-in ovens which allowed the household to bake at home. Industrial chimneys became common in the late 18th century.

Chimneys in ordinary dwellings were first built of wood and plaster or mud. Since then chimneys have traditionally been built of brick or stone, both in small and large buildings. Early chimneys were of simple brick construction. Later chimneys were constructed by placing the bricks around tile liners. To control downdrafts, venting caps (often called chimney pots) with a variety of designs are sometimes placed on the top of chimneys.

In the 18th and 19th centuries, the methods used to extract lead from its ore produced large amounts of toxic fumes. In the north of England, long near-horizontal chimneys were built, often more than 3 km (2 mi) long, which typically terminated in a short vertical chimney in a remote location where the fumes would cause less harm. Lead and silver deposits formed on the inside of these long chimneys, and periodically workers would be sent along the chimneys to scrape off these valuable deposits.

Construction

left|thumb|Chimney in [[NED University of Engineering and Technology|NED University]]

As a result of the limited ability to handle transverse loads with brick, chimneys in houses were often built in a "stack", with a fireplace on each floor of the house sharing a single chimney, often with such a stack at the front and back of the house. Today's central heating systems have made chimney placement less critical, and the use of non-structural gas vent pipe allows a flue gas conduit to be installed around obstructions and through walls.

thumb|Chimney in North London

left|thumb|Flue

Most modern high-efficiency heating appliances do not require a chimney. Such appliances are generally installed near an external wall, and a noncombustible wall thimble allows a vent pipe to run directly through the external wall.

On a pitched roof where a chimney penetrates a roof, flashing is used to seal up the joints. The down-slope piece is called an apron, the sides receive step flashing and a cricket is used to divert water around the upper side of the chimney underneath the flashing.

Industrial chimneys are commonly referred to as flue-gas stacks and are generally external structures, as opposed to those built into the wall of a building. They are generally located adjacent to a steam-generating boiler or industrial furnace and the gases are carried to them with ductwork. Today the use of reinforced concrete has almost entirely replaced brick as a structural element in the construction of industrial chimneys. Refractory bricks are often used as a lining, particularly if the type of fuel being burned generates flue gases containing acids. Modern industrial chimneys sometimes consist of a concrete windshield with a number of flues on the inside.

The high steam plant chimney at the Secunda CTL's synthetic fuel plant in Secunda, South Africa consists of a 26 m (85 ft) diameter windshield with four 4.6 metre diameter concrete flues which are lined with refractory bricks built on rings of corbels spaced at 10 metre intervals. The reinforced concrete can be cast by conventional formwork or sliding formwork. The height is to ensure the pollutants are dispersed over a wider area to meet legal or other safety requirements.

Residential flue liners

thumb|right|A chimney with two clay-tile flue liners

A flue liner is a secondary barrier in a chimney that protects the masonry from the acidic products of combustion, helps prevent flue gas from entering the house, and reduces the size of an oversized flue. Since the 1950s, building codes in many locations require newly built chimneys to have a flue liner. Chimneys built without a liner can usually have a liner added, but the type of liner needs to match the type of appliance it services. Flue liners may be clay or concrete tile, metal, or poured in place concrete.

Clay tile flue liners are very common in the United States, although it is the only liner that does not meet Underwriters Laboratories 1777 approval and frequently they have problems such as cracked tiles and improper installation. Clay tiles are usually about long, available in various sizes and shapes, and are installed in new construction as the chimney is built. A refractory cement is used between each tile.

Metal liners may be stainless steel, aluminum, or galvanized iron and may be flexible or rigid pipes. Stainless steel is made in several types and thicknesses. Type 304 is used with firewood, wood pellet fuel, and non-condensing oil appliances, types 316 and 321 with coal, and type AL 29-4C is used with high efficiency condensing gas appliances. Stainless steel liners must have a cap and be insulated if they service solid fuel appliances, but following the manufacturer's instructions carefully.

For aircraft operating near chimneys, exhausts or plumes may cause turbulence, reduced visibility, oxygen depletion, engine contamination, exposure to gaseous oxides, and icing. These effects are more pronounced in cold, calm and stable air when the plume is hot. Pilots are instructed to fly upwind away from the chimney to minimize the impact.

Maintenance and problems

A characteristic problem of chimneys is they develop deposits of creosote on the walls of the structure when used with wood as a fuel. Deposits of this substance can interfere with the airflow and more importantly, they are combustible and can cause dangerous chimney fires if the deposits ignite in the chimney.

Heaters that burn natural gas drastically reduce the amount of creosote buildup due to natural gas burning much cleaner and more efficiently than traditional solid fuels. While in most cases there is no need to clean a gas chimney on an annual basis that does not mean that other parts of the chimney cannot fall into disrepair. Disconnected or loose chimney fittings caused by corrosion over time can pose serious dangers for residents due to leakage of carbon monoxide into the home. Thus, it is recommended—and in some countries even mandatory—that chimneys be inspected annually and cleaned on a regular basis to prevent these problems. The workers who perform this task are called chimney sweeps or steeplejacks. This work used to be done largely by child labour and, as such, features in Victorian literature. In the Middle Ages in some parts of Europe, a stepped gable design was developed, partly to provide access to chimneys without use of ladders.

Masonry (brick) chimneys have also proven to be particularly prone to crumbling during earthquakes. Government housing authorities in cities prone to earthquakes such as San Francisco, Los Angeles, and San Diego now recommend building new homes with stud-framed chimneys around a metal flue. Bracing or strapping old masonry chimneys has not proven to be very effective in preventing damage or injury from earthquakes. It is now possible to buy "faux-brick" facades to cover these modern chimney structures.

Chimneys of special interest

Chimneys with observation decks

Several chimneys with observation decks were built. The following possibly incomplete list shows them.

{| class="wikitable sortable"

! Name

! Country

! Town

! Coordinates

! Year of completion

! Total height

! Height of observation deck

! Remarks

| Chimney of Beitou Refuse Incineration Plant || Taiwan || Teipei || || 2000 || 150 m (492 ft) || 116 m (381 ft) || revolving restaurant in a height of 120 metres (394 ft)

| Radio City Tower || United Kingdom || Liverpool || || 1971 || 148 m (486 ft) || 124.7 m (409 ft) || chimney for the heating system of a nearby mall

| Large Chimney of Warsaw Refuse Incineration Plant || Poland || Warsaw || || 2024 || 80 m (262 ft) || || observation deck only accessible at guided tours through the facility

| Bernard Brewery Chimney || Czech || Humpolec || || || 40.7 m (134 ft) || 33 m (108 ft) || observation deck added in 2020/21

| Dům Dětí a Mládeže v Modřanech || Czech || Prague || || 2004 || 15 m (49 ft) || 12 m (39 ft) || observation platform on chimney of the roof of a youth centre

| Chimney of Zenner Heating Building || Germany || Berlin || || 1955 || 15 m (49 ft) || 12 m (39 ft) || perhaps never in use as observation tower

Chimneys used as electricity pylon

At several thermal power stations at least one smokestack is used as electricity pylon. The following possibly incomplete list shows them.

{| class="wikitable"

! Country

! City

! Coordinates

! Name

! Height

! Year of construction

! Voltage

! Remarks

| Germany || Gelsenkirchen || || Scholven Power Station, Chimney for Units B, C, D and E || 300 m || || 220 kV ||

| Belarus || Novolukoml || || Lukoml Power Station, Chimney 1 || 250 m || 1969 || 330 kV ||

| Belarus || Novolukoml || || Lukoml Power Station, Chimney 2 || 250 m || 1971 || 330 kV ||

| Belarus || Novolukoml || || Lukoml Power Station, Chimney 3 || 250 m || 1973 || 330 kV ||

| Lithuania || Elektrenai || || Elektrėnai Power Plant, Chimney 1 || 150 m || || 330 kV || dismantled

| Lithuania || Elektrenai || || Elektrėnai Power Plant, Chimney 2 || 250 m || || 330 kV || dismantled

| Moldova || Dnestrovsc || || Cuciurgan power station, Chimney 1 || 180 m || 1964 || 110 kV ||

| Moldova || Dnestrovsc || || Cuciurgan power station, Chimney 2 || 180 m || 1966 || 330 kV ||

| Moldova || Dnestrovsc || || Cuciurgan power station, Chimney 3 || 180 m || 1971 || 330 kV ||

| Russia || Archangelsk || || Archangelsk Cogeneration Plant, Chimney 1 || 170 m || || 220 kV ||

| Russia || Saint Petersburg || || Vyborgskaya Cogenaration Plant, Chimney 1 || 120 m || || 110 kV ||

| Russia || Tobolsk || || TEC Tobolsk, Chimney 1 || 240 m || 1980 || 110 kV ||

| Russia || Tobolsk || || TEC Tobolsk, Chimney 2 || 270 m || 1986 || 220 kV ||

| Russia || Kashira || || Kashira Power Plant, Chimney 1 || 250 m || 1966 || 220 kV ||

| Russia || Energetik || || Iriklinskaya Power Station, Chimney 1 || 180 m || || 220 kV ||

| Russia || Energetik || || Iriklinskaya Power Station, Chimney 2 || 180 m || || 220 kV ||

| Russia || Energetik || || Iriklinskaya Power Station, Chimney 3 || 250 m || || 500 kV ||

| Russia || Konakovo || || Konakovo Power Station, Chimney 1 || 180 m || 1964 || 220 kV ||

| Russia || Konakovo || || Konakovo Power Station, Chimney 2 || 180 m || 1966 || 220 kV ||

| Russia || Koryazhma || || Chimney 1 of Cogenaration Plant 1 of Kotlas Pulp and Paper Mill || 105 m || 1961 || 220 kV ||

| Ukraine || Burshtyn || || Burshtyn Power Station, Chimney 1 || 180 m || 1965 || 330 kV ||

| Ukraine || Burshtyn || || Burshtyn Power Station, Chimney 2 || 250 m || 1966 || 330 kV ||

| Ukraine || Burshtyn || || Burshtyn Power Station, Chimney 3 || 250 m || 1966 || 330 kV ||

| Ukraine || Trypillia || || Trypillia Power Station, Chimney 1 || 180 m || 1968 || 330 kV ||

| Ukraine || Trypillia || || Trypillia Power Station, Chimney 2 || 180 m || 1972 || 330 kV ||

Nearly all of these structures exist in an area which was once part of the Soviet Union. Although this use has the disadvantage that conductor ropes may corrode faster due to the exhaust gases, one can find such structures also sometimes in countries not influenced by the former Soviet Union. An example herefore is one chimney of Scholven Power Plant in Gelsenkirchen, which carries one circuit of an outgoing 220 kV-line.

Chimneys used as water tower

Chimneys can also carry a water tank on their structure. This combination has the advantage that the warm smoke running through the chimney prevents the water in the tank from freezing. Before World War II such structures were not uncommon, especially in countries influenced by Germany.

Chimneys used as radio tower

Chimneys can carry antennas for radio relay services, cell phone transmissions, FM-radio and TV on their structure. Also long wire antennas for mediumwave transmissions can be fixed at chimneys.

In all cases it had to be considered that these objects can easily corrode especially when placed near the exhaust.

Sometimes chimneys were converted into radio towers and are not useable as ventilation structure any more.

Chimneys used for advertising

As chimneys are often the tallest part of a factory, they offer the possibility as advertising billboard either by writing the name of the company to which they belong on the shaft or by installing advertisement boards on their structure.

Cooling tower used as an industrial chimney

At some power stations, which are equipped with plants for the removal of sulfur dioxide and nitrogen oxides, it is possible to use the cooling tower as a chimney. Such cooling towers can be seen in Germany at the Großkrotzenburg Power Station and at the Rostock Power Station. At power stations that are not equipped for removing sulfur dioxide, such usage of cooling towers could result in serious corrosion problems which are not easy to prevent.

References

External links

CICIND – International Committee on Industrial Chimneys
Chimney Safety Institute of America
Power Station Konakovskaya GRES, at which chimneys serve as electricity pylons
Article about chimney breast removal
Chimney Maintenance Information
European Chimney Association ECA; to find further information on chimneys
National Association of Chimney Engineers; UK trade association for the chimney engineering industry
Collection of chimneys used as electricity pylons on Skyscraperpage.com