chimney |
celery |
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times more probable under chimney 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under celery (words not in the model) | |
A chimney'" is a structure for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. 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 a "flue". Chimneys may be found in buildings, steam locomotives and ships. In the US, the term smokestack'" (colloquially, "'stack'") is also used when referring to locomotive chimneys. The term "'funnel'" is generally used for ships' chimneys and sometimes to refer to locomotive chimneys.. Chimneys are tall to increase their draw of air for combustion and to disperse pollutants in the flue gases over a greater area so as to reduce the pollutant concentrations in compliance with regulatory or other limits. History. Romans used tubes inside the walls to draw smoke out of bakeries but real chimneys appeared only in northern Europe in the 12th century. Industrial chimneys became common in the late 18th century. The earliest extant example of an English chimney is at Conisborough Keep in Yorkshire, which dates from 1185 AD. Chimneys have traditionally been built of brick, both in small and large buildings. Early chimneys were of a 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 eighteenth and nineteenth 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. Due to brick's limited ability to handle transverse loads, 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. In fact, many modern high-efficiency heating appliances do not require a chimney. Such appliances are typically installed near an outside wall, and a noncombustible wall thimble allows vent pipe to be run directly through the outside wall. Industrial chimneys are commonly referred to as flue gas stacks and are typically external structures, as opposed to being 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 it with ductwork. Today the use of reinforced concrete has almost entirely replaced brick as a structural component 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 300 metre chimney at Sasol Three consists of a 26 metre 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 legislative or safety requirements. Chimney tops. A chimney pot is placed on top of the chimney to inexpensively extend the length of the chimney, and to improve the chimney's draft. A chimney with more than one pot on it indicates that there is more than one fireplace on different floors sharing the chimney. A chimney cowl is placed on top of the chimney to prevent birds and squirrels from nesting in the chimney. They often feature a rain guard to keep rain from going down the chimney. A metal wire mesh is often used as a spark arrestor to minimize burning debris from rising out of the chimney and making it onto the roof. Although the masonry inside the chimney can absorb a large amount of moisture which later evaporates, rainwater can collect at the base of the chimney. Sometimes weep holes are placed at the bottom of the chimney to drain out collected water. A chimney cowl or wind directional cap is helmet shaped chimney cap that rotates to align with the wind and prevent a backdraft of smoke and wind back down the chimney. An H-style cap'" (cowl) is a chimney top constructed from chimney pipes shaped like the letter H. It is an age old method to regulate draft in situations where prevailing winds or turbulences cause down draft and backpuffing. Although the "'H cap'" has a distinctive advantage over most other downdraft caps, it fell out of favor because of it bulky looks. It is found mainly in marine use but has been gaining popularity again due to its energy saving functionality. The "'H-cap stabilizes the draft rather than increasing it. Other down draft caps are based on the Venturi effect, solving downdraft problems by increasing the up draft constantly resulting in much higher fuel consumption. A chimney damper is a metal spring door placed at the top of the chimney with a long metal chain that allows you to open and close the chimney from the fireplace. In the late Middle Ages in Western Europe the design of crow-stepped gables arose to allow maintenance access to the chimney top, especially for tall structures such as castles and great manor houses. Chimney draught or draft. When coal, oil, natural gas, wood or any other fuel is combusted in a stove, oven, fireplace, hot water boiler or industrial furnace, the hot combustion product gases that are formed are called flue gases. Those gases are generally exhausted to the ambient outside air through chimneys or industrial flue gas stacks (sometimes referred to as smokestacks). The combustion flue gases inside the chimneys or stacks are much hotter than the ambient outside air and therefore less dense than the ambient air. That causes the bottom of the vertical column of hot flue gas to have a lower pressure than the pressure at the bottom of a corresponding column of outside air. That higher pressure outside the chimney is the driving force that moves the required combustion air into the combustion zone and also moves the flue gas up and out of the chimney. That movement or flow of combustion air and flue gas is called "natural draught draft", "natural ventilation", "chimney effect", or "stack effect". The taller the stack, the more draught or draft is created. Designing chimneys and stacks to provide the correct amount of natural draught or | "Apium graveolens" is a plant species in the family Apiaceae commonly known as celery'" (var. "dulce") or celeriac'" (var. "rapaceum") depending on whether the petioles or roots are eaten. Taxonomy. Celery was described by Carolus Linnaeus in Volume One of his "Species Plantarum" in 1753. The closely related "Apium bermejoi" from the island of Minorca is one of the rarest plants in Europe with only 60 individuals left. Uses. "Apium graveolens" is used around the world as a vegetable, either for the crisp petiole (leaf stalk) or the fleshy taproot. In temperate countries, celery is also grown for its seeds. Actually very small fruit, these "seeds" yield a valuable volatile oil used in the perfume and pharmaceutical industries. They also contain an organic compound called apiol. Celery seeds can be used as flavouring or spice either as whole seeds or, ground and mixed with salt, as celery salt. Celery salt can also be made from an extract of the roots. Celery salt is used as a seasoning, in cocktails (notably to enhance the flavour of Bloody Mary cocktails), on the Chicago-style hot dog, and in Old Bay Seasoning. Celery, onions, and bell peppers are the holy trinity of Louisiana Creole and Cajun cuisine. Celery, onions, and carrots make up the French mirepoix, often used as a base for sauces and soups. Celery is a staple in chicken noodle soup. Celery is an important ingredient in Indian cuisines including in Indian Curry. Celery is widely eaten by guinea pigs, dogs, horses, birds, squirrels, and small rodents. Medicine. The use of celery seed in pills for relieving pain was described by Aulus Cornelius Celsus ca. 30 AD. Nutrition. Celery is valuable in weight-loss diets, where it provides low-calorie fiber bulk. Celery contains androstenone, not androsterone. Bergapten in the seeds can increase photosensitivity, so the use of essential oil externally in bright sunshine should be avoided. The oil and large doses of seeds should be avoided during pregnancy: they can act as a uterine stimulant. Seeds intended for cultivation are not suitable for eating as they are often treated with fungicides. There is a common belief that celery is so difficult for humans to digest, that it has negative calories because human digestion burns more calories than can be extracted. Allergies. Although many people enjoy foods made with celery, a small minority of people can have severe allergic reactions. For people with celery allergy, exposure can cause potentially fatal anaphylactic shock. The allergen does not appear to be destroyed at cooking temperatures. Celery root—commonly eaten as celeriac, or put into drinks—is known to contain more allergen than the stalk. Seeds contain the highest levels of allergen content. Celery is amongst a small group of foods (headed by peanuts) that appear to provoke the most severe allergic reactions (anaphylaxis). Exercise-induced anaphylaxis may be exacerbated. An allergic reaction also may be triggered by eating foods that have been processed with machines that have previously processed celery, making avoiding such foods difficult. In contrast with peanut allergy being most prevalent in the US, celery allergy is most prevalent in Central Europe. In the European Union, foods that contain or may contain celery, even in trace amounts, have to be clearly marked as such. History. Zohary and Hopf note that celery leaves and inflorescences were part of the garlands found in the tomb of Tutankhamun, pharaoh of ancient Egypt, and celery mericarps dated to the 7th century BC were recovered in the Heraion of Samos. However, they note "since "A. graveolens" grows wild in these areas it is hard to decide whether these remains represent wild or cultivated forms." Only by classical times is it certain that celery was cultivated. M. Fragiska mentions an archeological find of celery dating to the 9th century BC, at Kastanas; however, the literary evidence for ancient Greece is far more abundant. In Homer's "Iliad", the horses of Myrmidons graze on wild celery that grows in the marshes of Troy, and in "Odyssey" there is mention of the meadows of violet and wild celery surrounding the cave of Calypso. Cultural depictions. A chthonian symbol, celery was said to have sprouted from the blood of Kadmilos, father of the Cabers, chthonian divinities celebrated in Samothrace, Lemnos and Thebes. The spicy odour and dark leaf colour encouraged this association with the cult of death. In classical Greece celery leaves were used as garlands for the dead, and the wreaths of the winners at the Isthmian Games were first made of celery before being replaced by crowns made of pine. According to Pliny the Elder ("Natural History" XIX.46), in Archaia the garland worn by the winners of the sacred contest at Nemea was also made of celery. Celery is eaten at the end of each adventure by the Wonder Pets in the American animated children's television series. Cultivation. "Apium graveolens" grows to 1 m (3 ft) tall. The leaves are pinnate to bipinnate leaves with rhombic leaflets 3-6 cm long and 2-4 cm broad. The flowers are creamy-white, 2-3 mm diameter, produced in dense compound umbels. The seeds are broad ovoid to globose, 1.5-2 mm long and wide. In North America, commercial production of celery is dominated by a variety called Pascal celery. Gardeners can grow a range of cultivars, many of which differ little from the wild species, mainly in having stouter leaf stems. They are ranged under two classes, white and red; the white cultivars being generally the best flavoured, and the most crisp and tender. The wild form of celery is known as "smallage". It has a furrowed stalk with wedge-shaped leaves, the whole plant having a coarse, earthy taste, and a distinctive smell. With cultivation and blanching, the stalks lose their acidic qualities and assume the mild, sweetish, aromatic taste particular to celery as a salad plant. The plants are raised from seed, sown either in a hot bed or in the open garden according to the season of the year, and after one or two thinnings out and transplantings they are, on attaining a height of 15-20 cm, planted out in deep trenches for convenience of blanching, which is affected by earthing up to exclude light from the stems. In the past, celery was grown as a vegetable for winter and early spring; because of its antitoxic properties, it was perceived as a cleansing tonic, welcomed after the stagnation of winter. Harvesting and storage. Harvesting occurs when the average size of celery in a field is marketable; due to extremely uniform crop growth, fields are harvested only once. Petioles and leaves are removed and harvested celery are packed by size and quality (determined by color, shape, straightness and thickness of petiole, stalk and midrib length and absence of disease, cracks, splits, insect damage and rot). Under optimal conditions, celery can be stored for up to seven weeks between 0 to 2°C (32 to 36°F). Inner stalks may continue growing if kept at temperatures above 0°C (32°F). Freshly-cut petioles of celery are prone to decay, which can be prevented or reduced through the use of sharp blades during processing, gentle handling, and proper sanitation. |