An oil skimmer is a device, designed to remove oil floating on a liquid surface. Depending on the specific design they are used for a variety of applications such as oil spill response, as a part of oily water treatment systems, removing oil from machine tool coolant and aqueous parts washers, collecting fats oils and greases in wastewater treatment in food manufacturing industries. Oil skimmers were used to great effect to assist in the remediation of the Exxon Valdez spill in 1989. Oil skimmers are different to Swimming pool sanitation skimmers that are designed for a related but different purpose. There are many different types of oil skimmer; each type has different design features and therefore results in different applications and use. It is important to understand the design features before employing a particular skimmer type; some factors to consider are: Oil removal flow rate: Alternative Skimmer designs have different oil removal flow rates. Volume removal rates for Oleophilic skimmer types are comparatively low.
Weir type skimmers are capable of high oil and water removal rates. ASTM F2709 standard establishes the test procedure for determining oil recovery rate. Oil removal concentration: It is a common misconception that oil skimmers remove concentrated or pure'oil'. In most situations the'oil' mixture removed is an emulsion of oil and water more like a'mousse'. Oleophilic and Non-Oleophilic skimmers can provide a more concentrated oil in the removal stream, however still collect entrained water. Effectiveness with different oils: Oleophilic and Non-Oleophilic skimmers are not effective with all oil types due to the changing nature of the attraction forces with different oils and materials. Effectiveness with chemicals in the water: Oleophilic skimmers may not work as if there are detergents, cleaners or other surfactants in the water that interfere with the oleophilic attraction. Weir skimmers are not affected by chemicals. Effects of trash and debris: Trash and debris may block or interfere with the operation of oil skimmers.
Skimming direction: Some skimmers only remove oil from one direction. In some situations, such as skimming from pits and tanks, it can be important to remove oil from all directions. Service Access: Some skimmers such as disc skimmers, or weir skimmers with skimmer mounted pumps, contain heavy serviceable items of equipment mounted on the skimmer; this may require special lifting equipment and confined space entry safety considerations before servicing. The use of skimmers in industrial applications is required to remove oils and fats prior to further treatment for environmental discharge compliance. By removing the top layer of oils, water stagnation and unsightly surface scum can be reduced. Placed before an oily water treatment system an oil skimmer may give greater overall oil separation efficiency for improved discharge wastewater quality. All oil skimmers will pick up a percentage of water with the oil which will need to be decanted to obtain concentrated oil. There are four main types of oil skimmer: weir and belt and oleophilic and non-oleophilic: Weir skimmers function by allowing the oil floating on the surface of the water to flow over a weir.
There are two main types of weir skimmer, those that require the weir height to be manually adjusted and those where the weir height is automatic or self-adjusting. Whilst manually adjusted weir skimmer types can have a lower initial cost, the requirement for regular manual adjustment makes self-adjusting weir types more popular in most applications. Weir skimmers will collect water if operating. To overcome this limitation most weir type skimmers contain an automatic water drain on the oil collection tank.. Belt oil skimmers is one of the most reliable and economical equipment removing liquid surface floating oil, low electric consumption, no need any consumable, can effective remove all kinds of floating oil, can make oil-water separation and waste oil reuse, its principle is adopt different gravity and surface tension etc characteristic, when the oil skimming belt pass water surface can absorb and take away the surface all kinds of floating oil. Oleophilic skimmers function by using an element such as a drum, rope or mop to which the oil adheres.
The oil is collected in a tank. As the oil is adhering to a collection surface the amount of water collected when oil is not present will be limited. Non-oleophilic skimmers are distinguished by the component used to collect the oil. A metal disc, belt or drum is used in applications where an oleophilic material is inappropriate, such as in a hot alkaline aqueous parts washer; the skimmer is turned off whenever there is no oil to skim thus minimizing the amount of water collected. Metal skimming elements are nearly as efficient as oleophilic skimmers; some oil skimming designs entered the Wendy Schmidt Oil Cleanup X CHALLENGE in 2011. The winning technology utilized Grooves placed on the surface of rotating discs manufactured by Elastec Inc of the USA; the revolutionary oil skimming technology won the X Prize Foundation’s Wendy Schmidt Oil Cleanup X CHALLENGE by recovering oil at a rate of 4,760 gallons per minute and an oil-to-water efficiency rate of 89.5% List of waste-water treatment technologies
An evaporator is a device in a process used to turn the liquid form of a chemical substance such as water into its gaseous-form/vapor. The liquid is vaporized, into a gas form of the targeted substance in that process. One kind of evaporator is a kind of radiator coil used in a closed compressor driven circulation of a liquid coolant; that is called an air-conditioning system or refrigeration system to allow a compressed cooling chemical, such as R-22 or R-410A, to evaporate/vaporize from liquid to gas within the system while absorbing heat from the enclosed cooled area, for example a refrigerator or rooms indoors, in the process. This works in the closed A/C or refrigeration system with a condenser radiator coil that exchanges the heat from the coolant, such as into the ambient environment. A different kind of evaporator can be used for heating and boiling a product containing a liquid to cause the liquid to evaporate from the product; the appropriate process can be used to remove water or other liquids from liquid based mixtures.
The process of evaporation is used to concentrate liquid foods, such as soup or make concentrated milk called "condensed milk" done by evaporating water from the milk. In the concentration process, the goal of evaporation is to vaporize most of the water from a solution which contains the desired product. An evaporator/evaporative-process can be used for separating liquid chemicals as well as to salvage solvents. In the case of desalination of sea water or in Zero Liquid Discharge plants, the reverse purpose applies. One of the most important applications of evaporation is in the beverage industry. Foods or beverages that need to last for a considerable amount of time or need to have certain consistency, like coffee, go through an evaporation step during processing. In the pharmaceutical industry, the evaporation process is used to eliminate excess moisture, providing an handled product and improving product stability. Preservation of long-term activity or stabilization of enzymes in laboratories are assisted by the evaporation process.
Another example of evaporation is in the recovery of sodium hydroxide in kraft pulping. Cutting down waste-handling cost is another major reason for large companies to use evaporation applications. All producers of waste must dispose of waste using methods compatible with environmental guidelines. By removing moisture through vaporization, industry can reduce the amount of waste product that must be processed. Water can be removed from solutions in ways other than evaporation, including membrane processes, liquid-liquid extractions and precipitation. Evaporation can be distinguished from some other drying methods in that the final product of evaporation is a concentrated liquid, not a solid, it is relatively simple to use and understand since it has been used on a large scale, many techniques are well known. In order to concentrate a product by water removal, an auxiliary phase is used which allows for easy transport of the solvent rather than the solute. Water vapor is used as the auxiliary phase when concentrating non-volatile components, such as proteins and sugars.
Heat is added to the solution, part of the solvent is converted into vapor. Heat is the main tool in evaporation, the process occurs more at high temperature and low pressures. Heat is needed to provide enough energy for the molecules of the solvent to leave the solution and move into the air surrounding the solution; the energy needed can be expressed as an excess thermodynamic potential of the water in the solution. Leading to one of the biggest problems in industrial evaporation, the process requires enough energy to remove the water from the solution and to supply the heat of evaporation; when removing the water, more than 99% of the energy needed goes towards supplying the heat of evaporation. The need to overcome the surface tension of the solution requires energy; the energy requirement of this process is high because a phase transition must be caused. When designing evaporators, engineers must quantify the amount of steam needed for every mass unit of water removed when a concentration is given.
An energy balance must be used based on an assumption that a negligible amount of heat is lost to the system's surroundings. The heat that needs to be supplied by the condensing steam will equal the heat needed to vaporize the water. Another consideration is the size of the heat exchanger; some common terms for understanding heat transfer: A = heat transfer area, q = overall heat transfer rate, U = overall heat transfer coefficient. The solution containing the desired product is fed into the evaporator and passes across a heat source; the applied heat converts the water in the solution into vapor. The vapor is removed from the rest of the solution and is condensed while the now-concentrated solution is either fed into a second evaporator or is removed; the evaporator, as a machine consists of four sections. The heating section contains the heating medium. Steam is fed into this section; the most common medium consists of parallel tubes but others have plates or coils made from copper or aluminium.
The concentrating and separating section removes the vapor being produced from the solution. The condenser condenses the separated vapor the vacuum or pump provides pressure to increase circulation. Natural circulation evaporators are based on the natural circulation of the product caused by the density differences that arise from heating. In an evapora
In geotechnical engineering, drilling fluid called drilling mud, is used to aid the drilling of boreholes into the earth. Used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are used for much simpler boreholes, such as water wells; the three main categories of drilling fluids are: water-based muds, which can be dispersed and non-dispersed. Along with their formatives, these are used along with appropriate polymer and clay additives for drilling various oil and gas formations; the main functions of drilling fluids include providing hydrostatic pressure to prevent formation fluids from entering into the well bore, keeping the drill bit cool and clean during drilling, carrying out drill cuttings, suspending the drill cuttings while drilling is paused and when the drilling assembly is brought in and out of the hole. The drilling fluid used for a particular job is selected to avoid formation damage and to limit corrosion. Source:Many types of drilling fluids are used on a day-to-day basis.
Some wells require that different types be used at different parts in the hole, or that some types be used in combination with others. The various types of fluid fall into a few broad categories: Air: Compressed air is pumped either down the bore hole's annular space or down the drill string itself. Air/water: The same as above, with water added to increase viscosity, flush the hole, provide more cooling, and/or to control dust. Air/polymer: A specially formulated chemical, most referred to as a type of polymer, is added to the water & air mixture to create specific conditions. A foaming agent is a good example of a polymer. Water: Water by itself is sometimes used. In offshore drilling sea water is used while drilling the top section of the hole. Water-based mud: Most basic water-based mud systems begin with water clays and other chemicals are incorporated into the water to create a homogeneous blend resembling something between chocolate milk and a malt; the clay is a combination of native clays that are suspended in the fluid while drilling, or specific types of clay that are processed and sold as additives for the WBM system.
The most common of these is bentonite referred to in the oilfield as "gel". Gel makes reference to the fact that while the fluid is being pumped, it can be thin and free-flowing, though when pumping is stopped, the static fluid builds a "gel" structure that resists flow; when an adequate pumping force is applied to "break the gel", flow resumes and the fluid returns to its free-flowing state. Many other chemicals are added to a WBM system to achieve various effects, including: viscosity control, shale stability, enhance drilling rate of penetration and lubricating of equipment. Oil-based mud: Oil-based mud is a mud where the base fluid is a petroleum product such as diesel fuel. Oil-based muds are used for many reasons, including increased lubricity, enhanced shale inhibition, greater cleaning abilities with less viscosity. Oil-based muds withstand greater heat without breaking down; the use of oil-based muds has special considerations, including cost, environmental considerations such as disposal of cuttings in an appropriate place, the exploratory disadvantages of using oil-based mud in wildcat wells.
Using an oil-based mud interferes with the geochemical analysis of cuttings and cores and with the determination of API gravity because the base fluid cannot be distinguished from oil returned from the formation. Synthetic-based fluid: Synthetic-based fluid is a mud where the base fluid is a synthetic oil; this is most used on offshore rigs because it has the properties of an oil-based mud, but the toxicity of the fluid fumes are much less than an oil-based fluid. This is important when men work with the fluid in an enclosed space such as an offshore drilling rig. Synthetic-based fluid poses the same environmental and analysis problems as oil-based fluid. On a drilling rig, mud is pumped from the mud pits through the drill string where it sprays out of nozzles on the drill bit and cooling the drill bit in the process; the mud carries the crushed or cut rock up the annular space between the drill string and the sides of the hole being drilled, up through the surface casing, where it emerges back at the surface.
Cuttings are filtered out with either a shale shaker, or the newer shale conveyor technology, the mud returns to the mud pits. The mud pits let the drilled "fines" settle; the returning mud can contain natural gases or other flammable materials which will collect in and around the shale shaker / conveyor area or in other work areas. Because of the risk of a fire or an explosion if they ignite, special monitoring sensors and explosion-proof certified equipment is installed, workers are advised to take safety precautions; the mud is pumped back down the hole and further re-circulated. After testing, the mud is treated periodically in the mud pits to ensure properties which optimize and improve drilling efficiency, borehole stability, other requirements listed below; the main functions of a drilling mud can be summarized as follows: Drilling fluid carries the rock excavated by the drill bit up to the surface. Its ability to do so depends on cutting size and density, speed of fluid traveling up the well.
These considerations are analogo
Sulfuric acid known as vitriol, is a mineral acid composed of the elements sulfur and hydrogen, with molecular formula H2SO4. It is a colorless and syrupy liquid, soluble in water, in a reaction, exothermic, its corrosiveness can be ascribed to its strong acidic nature, and, if at a high concentration, its dehydrating and oxidizing properties. It is hygroscopic absorbing water vapor from the air. Upon contact, sulfuric acid can cause severe chemical burns and secondary thermal burns. Sulfuric acid is a important commodity chemical, a nation's sulfuric acid production is a good indicator of its industrial strength, it is produced with different methods, such as contact process, wet sulfuric acid process, lead chamber process and some other methods. Sulfuric acid is a key substance in the chemical industry, it is most used in fertilizer manufacture, but is important in mineral processing, oil refining, wastewater processing, chemical synthesis. It has a wide range of end applications including in domestic acidic drain cleaners, as an electrolyte in lead-acid batteries, in various cleaning agents.
Although nearly 100% sulfuric acid can be made, the subsequent loss of SO3 at the boiling point brings the concentration to 98.3% acid. The 98.3% grade is more stable in storage, is the usual form of what is described as "concentrated sulfuric acid". Other concentrations are used for different purposes; some common concentrations are: "Chamber acid" and "tower acid" were the two concentrations of sulfuric acid produced by the lead chamber process, chamber acid being the acid produced in the lead chamber itself and tower acid being the acid recovered from the bottom of the Glover tower. They are now obsolete as commercial concentrations of sulfuric acid, although they may be prepared in the laboratory from concentrated sulfuric acid if needed. In particular, "10M" sulfuric acid is prepared by adding 98% sulfuric acid to an equal volume of water, with good stirring: the temperature of the mixture can rise to 80 °C or higher. Sulfuric acid reacts with its anhydride, SO3, to form H2S2O7, called pyrosulfuric acid, fuming sulfuric acid, Disulfuric acid or oleum or, less Nordhausen acid.
Concentrations of oleum are either expressed in terms of % SO3 or as % H2SO4. Pure H2S2O7 is a solid with melting point of 36 °C. Pure sulfuric acid has a vapor pressure of <0.001 mmHg at 25 °C and 1 mmHg at 145.8 °C, 98% sulfuric acid has a <1 mmHg vapor pressure at 40 °C. Pure sulfuric acid is a viscous clear liquid, like oil, this explains the old name of the acid. Commercial sulfuric acid is sold in several different purity grades. Technical grade H2SO4 is impure and colored, but is suitable for making fertilizer. Pure grades, such as United States Pharmacopeia grade, are used for making pharmaceuticals and dyestuffs. Analytical grades are available. Nine hydrates are known, but four of them were confirmed to be tetrahydrate and octahydrate. Anhydrous H2SO4 is a polar liquid, having a dielectric constant of around 100, it has a high electrical conductivity, caused by dissociation through protonating itself, a process known as autoprotolysis. 2 H2SO4 ⇌ H3SO+4 + HSO−4The equilibrium constant for the autoprotolysis is Kap = = 2.7×10−4The comparable equilibrium constant for water, Kw is 10−14, a factor of 1010 smaller.
In spite of the viscosity of the acid, the effective conductivities of the H3SO+4 and HSO−4 ions are high due to an intramolecular proton-switch mechanism, making sulfuric acid a good conductor of electricity. It is an excellent solvent for many reactions; because the hydration reaction of sulfuric acid is exothermic, dilution should always be performed by adding the acid to the water rather than the water to the acid. Because the reaction is in an equilibrium that favors the rapid protonation of water, addition of acid to the water ensures that the acid is the limiting reagent; this reaction is best thought of as the formation of hydronium ions: H2SO4 + H2O → H3O+ + HSO−4 Ka1 = 2.4×106 HSO−4 + H2O → H3O+ + SO2−4 Ka2 = 1.0×10−2 HSO−4 is the bisulfate anion and SO2−4 is the sulfate anion. Ka1 and Ka2 are the acid dissociation constants; because the hydration of sulfuric acid is thermodynamically favorable and the affinity of it for water is sufficiently strong, sulfuric acid is an excellent dehydrating agent.
Concentrated sulfuric acid has a powerful dehydrating property, removing water from other chemical compounds including sugar and other carbohydrates and producing carbon and steam. In the laboratory, this is demonstrated by mixing table sugar into sulfuric acid; the sugar changes from white to dark brown and to black as carbon is formed. A rigid column of black, porous carbon will emerge as well; the carbon will smell of caramel due to the heat generated. C 12 H 22 O 11 ⏞ sucrose → H 2 SO 4 12 C + 11 H 2
A centrifuge is a piece of equipment that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis of spin that can be strong. The centrifuge works using the sedimentation principle, where the centrifugal acceleration causes denser substances and particles to move outward in the radial direction. At the same time, objects that are less dense move to the center. In a laboratory centrifuge that uses sample tubes, the radial acceleration causes denser particles to settle to the bottom of the tube, while low-density substances rise to the top. There are three types of centrifuge designed for different applications. Industrial scale centrifuges are used in manufacturing and waste processing to sediment suspended solids, or to separate immiscible liquids. An example is the cream separator found in dairies. High speed centrifuges and ultracentrifuges able to provide high accelerations can separate fine particles down to the nano-scale, molecules of different masses.
Large centrifuges are used to simulate high acceleration environments. Medium-sized centrifuges are used in washing machines and at some swimming pools to wring water out of fabrics. Gas centrifuges are used for isotope separation, such as to enrich nuclear fuel for fissile isotopes. English military engineer Benjamin Robins invented a whirling arm apparatus to determine drag. In 1864, Antonin Prandtl proposed the idea of a dairy centrifuge to separate cream from milk; the idea was subsequently put into practice by his brother, Alexander Prandtl, who made improvements to his brother's design, exhibited a working butterfat extraction machine in 1875. A centrifuge machine can be described as a machine with a rotating container that applies centrifugal force to its contents. There are multiple types of centrifuge, which can be classified by intended use or by rotor design: Types by rotor design: Fixed-angle centrifuges are designed to hold the sample containers at a constant angle relative to the central axis.
Swinging head centrifuges, in contrast to fixed-angle centrifuges, have a hinge where the sample containers are attached to the central rotor. This allows all of the samples to swing outwards. Continuous tubular centrifuges do not have individual sample vessels and are used for high volume applications. Types by intended use: Laboratory centrifuges, are general-purpose instruments of several types with distinct, but overlapping, capabilities; these include superspeed centrifuges and preparative ultracentrifuges. Analytical ultracentrifuges are designed to perform sedimentation analysis of macromolecules using the principles devised by Theodor Svedberg. Haematocrit centrifuges are used to measure the volume percentage of red blood cells in whole blood. Gas centrifuges, including Zippe-type centrifuges, for isotopic separations in the gas phase. Industrial centrifuges may otherwise be classified according to the type of separation of the high density fraction from the low density one. There are two types of centrifuges: the filtration and sedimentation centrifuges.
For the filtration or the so-called screen centrifuge the drum is perforated and is inserted with a filter, for example a filter cloth, wire mesh or lot screen. The suspension flows through the filter and the drum with the perforated wall from the inside to the outside. In this way the solid material can be removed; the kind of removing depends on the type of centrifuge, for example manually or periodically. Common types are: Screen/scroll centrifuges Pusher centrifuges Peeler centrifuges Inverting filter centrifuges Sliding discharge centrifuges Pendulum centrifugesIn the sedimentation centrifuges the drum is a solid wall; this type of centrifuge is used for the purification of a suspension. For the acceleration of the natural deposition process of suspension the centrifuges use centrifugal force. With so-called overflow centrifuges the suspension is drained off and the liquid is added constantly. Common types are: Pendulum centrifuges. Though most modern centrifuges are electrically powered, a hand-powered variant inspired by the whirligig has been developed for medical applications in developing countries.
A wide variety of laboratory-scale centrifuges are used in chemistry, biology and clinical medicine for isolating and separating suspensions and immiscible liquids. They vary in speed, temperature control, other characteristics. Laboratory centrifuges can accept a range of different fixed-angle and swinging bucket rotors able to carry different numbers of centrifuge tubes and rated for specific maximum speeds. Controls vary from simple electrical timers to programmable models able to control acceleration and deceleration rates, running speeds, temperature regimes. Ultracentrifuges spin the rotors under vacuum, eliminating air resistance and enabling exact temperature control. Zonal rotors and continuous flow systems are capable of handing bulk and larger sample volumes in a laboratory-scale instrument. Another application in laboratories is blood separation. Blood separates into cells and proteins
Natural rubber called India rubber or caoutchouc, as produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds, plus water. Thailand and Indonesia are two of the leading rubber producers. Forms of polyisoprene that are used as natural rubbers are classified as elastomers. Rubber is harvested in the form of the latex from the rubber tree or others; the latex is a sticky, milky colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex is refined into rubber ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup; the coagulated lumps are processed into dry forms for marketing. Natural rubber is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has a large stretch ratio and high resilience, is waterproof; the major commercial source of natural rubber latex is the Pará rubber tree, a member of the spurge family, Euphorbiaceae.
This species is preferred. A properly managed tree responds to wounding by producing more latex for several years. Congo rubber a major source of rubber, came from vines in the genus Landolphia. Dandelion milk contains latex; the latex exhibits the same quality as the natural rubber from rubber trees. In the wild types of dandelion, latex content varies greatly. In Nazi Germany, research projects tried to use dandelions as a base for rubber production, but failed. In 2013, by inhibiting one key enzyme and using modern cultivation methods and optimization techniques, scientists in the Fraunhofer Institute for Molecular Biology and Applied Ecology in Germany developed a cultivar, suitable for commercial production of natural rubber. In collaboration with Continental Tires, IME began a pilot facility. Many other plants produce forms of latex rich in isoprene polymers, though not all produce usable forms of polymer as as the Pará; some of them require more elaborate processing to produce anything like usable rubber, most are more difficult to tap.
Some produce other desirable materials, for example chicle from Manilkara species. Others that have been commercially exploited, or at least showed promise as rubber sources, include the rubber fig, Panama rubber tree, various spurges, the related Scorzonera tau-saghyz, various Taraxacum species, including common dandelion and Russian dandelion, most for its hypoallergenic properties, guayule; the term gum rubber is sometimes applied to the tree-obtained version of natural rubber in order to distinguish it from the synthetic version. The first use of rubber was by the indigenous cultures of Mesoamerica; the earliest archeological evidence of the use of natural latex from the Hevea tree comes from the Olmec culture, in which rubber was first used for making balls for the Mesoamerican ballgame. Rubber was used by the Maya and Aztec cultures – in addition to making balls Aztecs used rubber for other purposes such as making containers and to make textiles waterproof by impregnating them with the latex sap.
The Pará rubber tree is indigenous to South America. Charles Marie de La Condamine is credited with introducing samples of rubber to the Académie Royale des Sciences of France in 1736. In 1751, he presented a paper by François Fresneau to the Académie that described many of rubber's properties; this has been referred to as the first scientific paper on rubber. In England, Joseph Priestley, in 1770, observed that a piece of the material was good for rubbing off pencil marks on paper, hence the name "rubber", it made its way around England. In 1764 François Fresnau discovered. Giovanni Fabbroni is credited with the discovery of naphtha as a rubber solvent in 1779. South America remained the main source of latex rubber used during much of the 19th century; the rubber trade was controlled by business interests but no laws expressly prohibited the export of seeds or plants. In 1876, Henry Wickham smuggled 70,000 Pará rubber tree seeds from Brazil and delivered them to Kew Gardens, England. Only 2,400 of these germinated.
Seedlings were sent to India, British Ceylon, Dutch East Indies and British Malaya. Malaya was to become the biggest producer of rubber. In the early 1900s, the Congo Free State in Africa was a significant source of natural rubber latex gathered by forced labor. King Leopold II's colonial state brutally enforced production quotas. Tactics to enforce the rubber quotas included removing the hands of victims to prove they had been killed. Soldiers came back from raids with baskets full of chopped-off hands. Villages that resisted were razed to encourage better compliance locally. See Atrocities in the Congo Free State for more information on the rubber trade in the Congo Free State in the late 1800s and early 1900s. Liberia and Nigeria started production. In India, commercial cultivation was introduced by British planters, although the experimental efforts to grow rubber on a commercial scale were initiated as early as 1873 at the Calcutta Botanical Gardens; the first commercial Hevea plantations were established at Thattekadu in Kerala in 1902.
In years the plantation expanded to Karnataka, Tamil Nadu and the Andaman and Nicobar Islands of India. India today is the
A pine is any conifer in the genus Pinus of the family Pinaceae. Pinus is the sole genus in the subfamily Pinoideae; the Plant List compiled by the Royal Botanic Gardens and Missouri Botanical Garden accepts 126 species names of pines as current, together with 35 unresolved species and many more synonyms. The modern English name "pine" derives from Latin pinus, which some have traced to the Indo-European base *pīt- ‘resin’. Before the 19th century, pines were referred to as firs. In some European languages, Germanic cognates of the Old Norse name are still in use for pines—in Danish fyr, in Norwegian fura/fure/furu, Swedish fura/furu, Dutch vuren, German Föhre—but in modern English, fir is now restricted to fir and Douglas fir. Pine trees are evergreen, coniferous resinous trees growing 3–80 m tall, with the majority of species reaching 15–45 m tall; the smallest are Siberian dwarf pine and Potosi pinyon, the tallest is an 81.79 m tall ponderosa pine located in southern Oregon's Rogue River-Siskiyou National Forest.
Pines are long lived and reach ages of 100–1,000 years, some more. The longest-lived is Pinus longaeva. One individual of this species, dubbed "Methuselah", is one of the world's oldest living organisms at around 4,600 years old; this tree can be found in the White Mountains of California. An older tree, now cut down, was dated at 4,900 years old, it was discovered in a grove beneath Wheeler Peak and it is now known as "Prometheus" after the Greek immortal. The bark of most pines is thick and scaly; the branches are produced in regular "pseudo whorls" a tight spiral but appearing like a ring of branches arising from the same point. Many pines are uninodal, producing just one such whorl of branches each year, from buds at the tip of the year's new shoot, but others are multinodal, producing two or more whorls of branches per year; the spiral growth of branches and cone scales may be arranged in Fibonacci number ratios. The new spring shoots are sometimes called "candles"; these "candles" offer foresters a means to evaluate fertility of the vigour of the trees.
Pines have four types of leaf: Seed leaves on seedlings are borne in a whorl of 4–24. Juvenile leaves, which follow on seedlings and young plants, are 2–6 cm long, green or blue-green, arranged spirally on the shoot; these are produced for six months to five years longer. Scale leaves, similar to bud scales, are small and not photosynthetic, arranged spirally like the juvenile leaves. Needles, the adult leaves, are green and bundled in clusters called fascicles; the needles can number from one to seven per fascicle, but number from two to five. Each fascicle is produced from a small bud on a dwarf shoot in the axil of a scale leaf; these bud scales remain on the fascicle as a basal sheath. The needles persist depending on species. If a shoot is damaged, the needle fascicles just below the damage will generate a bud which can replace the lost leaves. Pines are monoecious, having the male and female cones on the same tree, though a few species are sub-dioecious, with individuals predominantly, but not wholly, single-sex.
The male cones are small 1–5 cm long, only present for a short period, falling as soon as they have shed their pollen. The female cones take 1.5–3 years to mature after pollination, with actual fertilization delayed one year. At maturity the female cones are 3–60 cm long; each cone has numerous spirally. The seeds are small and winged, are anemophilous, but some are larger and have only a vestigial wing, are bird-dispersed. At maturity, the cones open to release the seeds, but in some of the bird-dispersed species, the seeds are only released by the bird breaking the cones open. In others, the seeds are stored in closed cones for many years until an environmental cue triggers the cones to open, releasing the seeds; the most common form of serotiny is pyriscence, in which a resin binds the cones shut until melted by a forest fire. Pines are gymnosperms; the genus is divided into two subgenera, which can be distinguished by cone and leaf characters: Pinus subg. Pinus, the yellow, or hard pine group with harder wood and two or three needles per fascicle Pinus subg.
Strobus, the white, or soft pine group with softer wood and five needles per fascicle Pines are native to the Northern Hemisphere, in a few parts of the tropics in the Southern Hemisphere. Most regions of the Northern Hemisphere host some native species of pines. One species crosses the equator in Sumatra to 2°S. In North America, various species occur in regions at latitudes from as far north as 66°N to as far south as 12°N. Pines may be found in a large variety of environments, ranging from semi-arid desert to rainforests, from sea level up to 5,200 metres, from the coldest to the hottest environments on Earth, they occur in mountainous areas with favorable soils and at least some water. Various species have been introduced to temperate and subtropical regions of both hemisp