A condenser is the equipment or equipment item used to condense (changing the physical state of a substance from its gas to its liquid form). In the laboratory, condensers are generally used in procedures involving organic liquids carried into the gas state by heating, with or without lowering pressure (applying vacuum) - although applications in the field of inorganic and other chemistry exist. While condensers can be applied to a variety of scales, in research, training, or discovery laboratories, most often use glasses designed to pass a steam stream over an adjacent cooling chamber. In its simplest form, such a condenser consists of a single glass tube with outside air which provides cooling. A further simpler form, the Liebig condenser type, involves a concentric glass tube, an inner passage of hot gas, and an outer space, "ported" through which the coolant passes, to reduce the internal gas temperature. , to pay for condensation.
Depending on the application (separated chemical components, and required operating temperature) and process scale (from very few microliters to processing of a multi-liter scale), different types of condensers and cooling means are used. In addition to the difference in temperature and heat capacity of the coolant (eg, air, water, aqueous organic co-solvent), the size of the cooling surface and the manner in which the gas (steam) and condensation of the liquid state come into contact are essential. in the choice or design of the condenser system. At least since the 19th century, scientists have sought creative designs to maximize the surface area of ​​vapor-liquid contact and heat exchange. Many types of laboratory condensers - Liebig and Allihn are simpler, rolled Graham type, simple cold finger condenser type and Dimroth, etc. - now common, have evolved to meet the practical needs of larger cooling surfaces and controlled boiling and condensation in various procedures involving distillation, and furthermore very much the material for simpler condenser "packing" to increase surface area (eg , glass, ceramics, and metal beads, rings, wool, etc.) have been studied and applied.
Likewise, the configuration of laboratory equipment involving numerous and varied condensers, to cover low and high boil solvents, simple and complex separations, etc. Several types of general processes based on changes in the physical state provided by the condenser can be easily explained, including simple evaporation or solvent removal (the mass removal of all volatiles to leave concentrated solutes present in the evaporated original solution) , the reflux operation (where the objective is to accommodate all volatiles while providing the constant process temperature specified by the boiling point of the solvent system used), and the separation/distillation operation where high theoretical plates provide selective delivery of one or more volatile components of a complex "mix" in a controlled way). The direction of the vapor and condensate flow in the selected condenser lab for each of these may vary (for example, being opposite in the reflux procedure, and concurrent in many simple distillation procedures), such as the optimal flow direction for the coolant, etc. In all processes, the choice of condenser/design requires that the heat entering the vapor never exceeds the condenser and cooling mechanisms; In addition, the thermal gradient and material flow formed during the gas-liquid transition are important aspects, so as the scale of the process from laboratory to pilot plant goes on, the design of the condenser system becomes an appropriate engineering science.
Video Condenser (laboratory)
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The condenser is a piece of equipment or apparatus which can be used to condense, that is, to change the physical state of a substance from its gas to its liquid form; in the laboratory, is generally used in procedures performed with organic liquids carried into the gas state through heating or vacuum applications (pressure is lowered), although the process often involves at least a trace amount of water in the general inorganic component, and may involve other inorganic substances. as well. Condensers can be applied on a variety of scales, from micro scale (very small microliters) to process scales (many liters), using laboratory glasses and sometimes metalware that complete steam cooling produced by boiling (through heating or vacuum applications).
In its simplest form, the condenser may consist of a single tube of glass or metal, in which the flow of external air produces cooling. In a further simpler form, the condenser consists of a concentric glass tube, with a tube through which hot gas begins to pass through a long run of apparatus. The second tube defines the outer space through which air, water, or other coolant may pass to reduce the temperature of the gas to pay for condensation; therefore, the outer tube (or, as the design becomes more complex, the outer cooling chamber) has an inlet and outlet to allow coolant in and out.
The special requirement that components in a "fractionated" solution (divided into component fractions) has different boiling points, and the various demands of heat exchange for various chemical processes using condensers has led to the design of vast varieties, with general design themes being the creative way in which :
- first, the surface area for the vapor-liquid interaction and heat exchange may be increased (leading to an increase in the number of theoretical plates, the metrics associated with the efficiency of the apparatus in separating the components with smaller boiling point differences), and second, the way to control common difficulties experienced in real distillation (such as "flooding and channeling", see below).
This combination has taken the concept of a simple condenser through a simple change (eg, addition, in a Allihn type condenser, from "bubbles" or undulations to an inner steam tube straight from a simple Liebig design), so diethyl ether (bp,.35 Â ° C), can be accommodated), in many unique condenser configurations, type "packets" of steam rooms, and applied cooling media and mechanisms (see below). In this design arrangement, the direction of vapor and condensate flow depends on the specific application (for example, being opposite in the reflux procedure, and simultaneously in many simpler distillation procedures); the same is true for the optimal flow direction for coolant fluids (air, water, ethylene glycol co-solution, etc.) relative to the direction of the vapor stream. Note, while traditional cooling, air and cold tap water, are often used without recirculation (ie, allowed to exit into the atmosphere or disposal, respectively), larger scale operations and urban and other regulations make recirculation engineering necessary, required for special cooling fluids, such as low temperature alcohols and co-solutions.
Designing and maintaining systems and processes using condensers requires that the heat of the incoming steam never overloads the capability of the selected condenser and cooling mechanism; also, the thermal gradient and material flow defined are important aspects, and as the scale of processes from the laboratory to the pilot plant and beyond, the design of the condenser system becomes the proper engineering science.
The use of condensers in chemical procedures - when not carried out at constant pressure and lowered by careful vacuum control - must involve temporary fluctuating pressure within the equipment, thus isolating the equipment while allowing it to be open rather than closed systems into practical issues; This is especially true, when chemical reactions are carried out that are sensitive to air or moisture. If a reaction or process using a condenser can not be left open to the atmosphere, the insulation is achieved in the simplest way through a drying tube (dry-mounted tube) or other special wrapping tube, allowing the gas to flow, and thus equalizing the pressure, but preventing entry substances that damage the ongoing chemical; Alternatively, the apparatus may be released via a "bubbler" which prevents the entry of the laboratory atmosphere either by allowing the internal volume to push and pull against the volume of the rejecting liquid (eg, mineral or silicone oil), or by maintaining positive pressure from the inert gas, "blanketing" eg, nitrogen or argon) that exit through the same fluid volume. Such an attachment during the tube and bubbler can be direct, or indirect through the gas/vacuum and manifold paths.
Practically, in modern milliliters for liter-scale laboratory operations involving condensers, the apparatus pieces are often held tightly together by complementary, tapered "inner" and "outer" "joints" ground to produce very tight connections (plus those required by PTFE ring or arm), or uniquely formulated oils or waxes; more and more, other means of glass joints, such as threaded fittings with adapters, are used (some of which are also used at various process scales.
Maps Condenser (laboratory)
Sample process
The condenser is often used in reflux, in which the hot solvent vapor of the heated liquid is cooled and allowed to re-drip. This reduces the loss of the solvent which allows the mixture to be heated for a long time. The condenser is used in distillation to cool the hot vapor, condensing it to a liquid for separate collection. For fractional distillation, air condenser or Vigreux is typically used to slow the rate at which steam rises, providing better separation between different components in the distillate. For micro distillation, the apparatus includes a "pot", and the condenser fuses into one piece, reducing the retaining volume, and obviating the need for a ground-glass connection that prevents contamination by fat and inhibits leakage.
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The simplest type of condenser consists of a single tube in which the steam heat is applied to a glass wall, which is only cooled by air; such as air condenser is often used for high boiling liquid condensation (ie, for distillation at high temperatures, well above 100 ° C), where columns can be used with or without packing (see below). Historically, the retort that appears in the illustrations of alchemical practice is a device that is essentially an unpacked air condenser. Liebig condensers are often used as air condensers, with air circulation rather than coolant (see next section).
A Vigreux column , named after the French glass blower, Henri Vigreux (December 16, 1869 - October 25 1951), is a type of air condenser in which a glass blower has modified a simple tube to include a downward indented indentation, thus dramatically increasing the surface area per unit length of the condenser; Vigreux columns were invented in 1904. Such columns are often used to add the theoretical plates required in fractional distillation, and present additional costs for their manufacture, which may include designs with or without outside glass cylinders (jackets), open to air or allow for fluid circulation , or, to assist in isolation, an outdoor vacuum jacket.
A Snyder Column is a highly air-cooled column used in certain fractional distillation. It is a single glass tube with a series of circular curves/restrictions on the cylindrical wall (eg, 3 or 6) where the remainder, inverted, equal amounts of a tear-shaped, empty, glass plug; above any point where an inverted teardrop is located, the cylinder has a further Vigreux-type indent, in this case serves to limit how high the glass stopper can be raised (by the steam stream) above its resting place, where, when it is not raised , it closes the circular opening created by a circular curve. This floating glass stopper acts as a check valve, closes and opens with a steam stream, and improves the vapor-condensate mixing. A standard application of the Snyder column, as a condenser/fractionation column above the Kuderna-Danish concentrator, is used to efficiently separate low-boiler extraction solvents such as methylene chloride from boiling extract components but higher than boiling (for example, after extraction of organic contaminants in the soil).
Further air condenser is a Widmer column, developed as a doctoral research project by student Gustav Widmer at ETH in the early 1920s, a type of complex air condenser that incorporates Golodetz-type concentric tubes and Dufton-glass-and-spiral-shape rods at its center (see figure).
The fluid-cooled type
Liebig Condenser
The condenser, known as the Liebig type, the most basic circulating refluxed-fluid design, was discovered by several researchers working independently; However, the earliest laboratory condenser was discovered in 1771 by the Swedish-German chemist Christian Weigel (1748-1831). The Weigel condenser consists of two coaxial tin tubes, which join at the lower end and open at the upper end. Cold water comes in, through the inlet, the bottom end of this jacket and spills out from the top end of the open jacket. The glass tube carries steam from the distillation flask through the inner tin tube, not in contact with the cooling water. Weigel then replaced the inner tin tube with a glass tube, and he made a clamp to hold the condenser. In 1791, German chemist Johann Friedrich August GÃÆ'¶ttling (1753-1809), who was a former pupil of Weigel, sealed the two ends of the Weigel condenser. The German chemist Justus Liebig (1803-1873) removed the inner walls of the Weigel condenser, placing, in direct contact with the jacket cooling water, the glass tube carrying steam from the distillation gourd. He was also replaced, with glass, the outer wall of the Weigel condenser. And he uses a rubber hose instead of a metal tube to bring water to and from the condenser.
The design was popularized by von Liebig so it consisted of an inner straight tube surrounded by an external straight tube, with an outer tube having a port for fluid inlet and outflow, and with two tubes sealed in several modes at the end (finally, by inflatable glass seal rings ). Its simplicity makes it comfortable to manufacture and inexpensive to produce, higher heat capacity than circulating water (vs. air) allows it to maintain a constant temperature in the condenser, and hence the Liebig type proves to be a more efficient condenser - is able to condense fluid from a stream that greater than the steam that enters - and therefore replaces the retort and air condenser. The added benefit of the simplicity of the inner tube design directly from this type of condenser is that it can be "packaged" with a material that increases the surface area (and so the number of theoretical plates of the distillation column, see below), for example, plastic, ceramics, and metal beads, rings, wool, etc. See Fractional Distillation.
Western Condenser
The variant of the Liebig condenser has a sleeker design, with cones and sockets. Narrowed cooling jackets may make cooling more efficient with respect to cooling consumption.
Condenser Allihn
Allihn condenser or "bulb condenser" or just "condenser reflux" is named after Felix Richard Allihn (1854-1915). Allihn condenser consists of long glass tube with water jacket. A series of bulbs on a tube increases the surface area at which the vapor constituents can condense. Ideally suited for laboratory scale reflux.
Davies condenser
The Davies condenser, also known as a double surface condenser, is similar to a Liebig condenser, but with three concentric glass tubes instead of two. Coolant circulates well outside the jacket and central tube. This increases the cooling surface, so the condenser can be shorter than the equivalent Liebig condenser.
Condensor Graham
The Graham condenser (also Grahams or Range Inside condenser) has a cooled jacketed spiral coil that runs the length of the condenser that serves as the steam/condensate line. This is not to be confused with "coil condenser". The inner circular condenser tube will provide more surface area for cooling and for this reason is most advantageous to use but the disadvantage of this condenser is because the vapor becomes viscous, it tends to move it into the vapor to evaporate which will also cause the flood of the solution mixture.
Condenser coil
The coil condenser is basically "Graham condenser" with an inverted cooling/vapor configuration. It has a spiral coil that runs the length of the condenser through which the coolant flows, and the cooling coil is jacketed by a steam/condensate path.
Dimroth condenser
A Dimroth condenser, named after Otto DimRoth, is somewhat similar to "coil condenser"; it has an internal double spiral through which the cooler flows so that the inlet and cooler outlets are both at the top. Steam drains the jacket from bottom to top. The dimroth condenser is more effective than conventional coil condensers. They are often found in rotary evaporators.
Spiral condenser
The spiral condenser has a spiral condensing tube with both inlet and outlet connections at the top, on the same side. See DimRoth condenser.
Condenser Friedrichs
A Friedrichs condenser (sometimes incorrectly referred to as "Friedrich's" condenser), a rotating finger condenser, was created by Fritz Walter Paul Friedrichs, who published the design for this type of condenser in 1912. It consists of a large internal cold finger, a spiral-type capillary tube dumped in a wide cylindrical housing. Coolant flows through the internal cold fingers; thus, steam rising through the housing must pass through the spiral path.
Condenser packing
During fractional distillation in the laboratory (or chemical plant), simple straight tubes can be packed with materials to increase the surface area, and therefore the theoretical number of plates; in the same way, a simple laboratory glass condensor surface area such as Liebig can be charged to improve performance. The same standard distillation packing material may be used - glass beads, rings, or helices (eg, Fenske rings), porcelain Ring Raschig or Lessing, or metal packaging of aluminum, copper, nickel, and stainless steels from most of the previous forms (eg, Lessing metal and Fenske types); glass packaging has further benefits with chemical inertia relevant to distillation of reactive chemicals (eg, hydrochloric acid), while metal packaging is easier to "condense" to "ensure uniform packaging".
The type of metal packing may extend to the packing of nickel and inconel wire (similar to Podbielniak columns), stainless steel gauze (Dixon ring), and indeed to any of the various special packaging methods used in distillation (eg, Hempel, Todd, and Stedman packing method); for example, a column full of cables of the Podbielniak function type by providing a large surface area for a vapor-liquid interaction with space such as a highly uniform capillary dispersing viscous fluid, so that the "channeling and flooding" in the column is "minimized", and giving, in one specific instance, added the number of theoretical plates 1-2 per 5 cm of packed length.
Coolant alternative
Source of the article : Wikipedia
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