Simply stated, the method quickly separates the volatile from the less volatile components using indirect heat transfer and mechanical agitation of the flowing product film under controlled conditions.The separation is normally made under vacuum conditions to maximize the temperature difference while maintaining the most favorable product temperature, as well as to maximize volatile stripping and recovery. CONSTRUCTION AND OPERATION OF EVAPORATORS. Tube – Tube dalam Horisontal Tube Evaporator merupakan tempat masaknya … All horizontal tube evaporator wholesalers & horizontal tube evaporator manufacturers come from members. Frequently, a tubular and agitated thin-film evaporator combination is the optimum solution (6). Wuhan Qiaoxin Refrigeration Equipment Co., Ltd. Evaporators are used in a wide range of processes, including pharmaceuticals, foods and beverages, pulp and paper, chemicals, polymers and resins, inorganic salts, acids, bases, and a variety of other materials. d. Rising /Ascending / climbing film evaporator, (2) Flat heating surface: plate evaporator. The concentrate is drained or pumped out of the tank through a nozzle (C). A continuous, horizontal tube evaporator is fed with a 50% caustic soda solution at 65°F and the product is continuously discharged at 230°F. The process should make a quality product with a good yield and minimum waste. The heating medium flows between every other plate. [Fig. Adequate velocities are needed to produce sufficient heat-transfer coefficients with-out exceeding limitations on pressure drop, erosion and entrainment. Various mechanisms such as inverted U-tube, spiral, baffle, centrifugal type are adopted for such separation. If the product is temperature-stable, then hot oil heating may allow higher temperatures and overcome the lower heat-transfer coefficient. The advantages of using a forced-circulation evaporator are: The primary disadvantages of forced circulation are: Typical applications where forced circulation should be used are sodium sulfate, urea, sodium chloride, ammonium sulfate, magnesium chloride, citric acid and caustic potash. A vertical gas flow, horizontal tube, natural or assisted circulation HRSG is shown schematically in Fig. Figure 4. There are four rows of tubes and each row has 12 tubes installed in four pass arrangements. ☆ Choose quality horizontal tube evaporator manufacturers, suppliers & exporters now - EC21 Evaporator film aduk Faktor Yang Mempengaruhi Evaporasi. The gaskets confine the fluids and prevent them from escaping into the atmosphere. The condenser is therefore the main vacuum pump and additional vacuum pumps such as steam jet air suction pumps, liquid seal pumps and others have only the purpose of removing non-condensable gases and thus maintaining the vacuum. Horizontal Tube Falling Film Evaporator for produced water. A gasketed plate-and-frame evaporator may be operated in arising-film, falling-film, or rising/falling-film mode. The vapour is removed from the top of the chamber and the product circulation is by natural circulation over the heating coil. We shall discuss here the most important types of evaporators which are of interest to the dairy industry. It can be built as a large single unit, partially due to the high heat-transfer performance exhibited undermost conditions, and partially because of the simplicity and low cost of construction. The horizontal tube falling film evaporator when compared with the vertical version not only has lower power consumption, reduced equipment height requirements, and smaller heat transfer temperature difference due to the high heat transfer coefficient and low … The advantage is it require small headroom and ability to arrange the bundle. Agitated thin-film, or wiped-film, evaporators are well-suited for processing difficult-to-handle materials. A rising/falling-film evaporator combines the advantages of both the rising-film and falling-film designs. The heating medium is steam. It looks very much like the forced circulation HRSG mentioned previously, with the primary difference being the elevation of the steam drums. The evaporator receives refrigerant from the thermostatic expansion valve or orifice tube as low pressure, cold atomized liquid. Leakage can be avoided by selecting the proper gasket for the application and following proper assembly procedures (5).  They are relatively low cost. The tubes are fabricated with special outside and inside profile to enhance heat transfer. (4). The combination of short residence time, narrow residence time distribution, high turbulence, and rapid surface renewal permits the agitated thin-film evaporator to successfully handle heat-sensitive, viscous and fouling materials. There are many types and variations of evaporators,and the best for a particular application depends on the product characteristics and desired results. In order to get a better understanding of distribution characteristics of the dynamic and heat transfer performance in a horizontal-tube evaporator, a numerical calculation was developed to simulate the internal film condensation and external falling film evaporation in a tube bundle. Condensate is removed from any convenient place on the bot-tom of the tubesheet (such as C), and the non-condensed gases are usually vented from somewhere near the upper tubesheet(e.g.,D). This type of unit is known as the Roberts evaporator in Europe and is the calandria evaporator in the United States. Continuity of operation – Batch and continuous. The heating medium flows inside the tubes of a horizontal tube evaporator. The evaporators can be classified in various ways depending on the construction of the evaporator, the method of feeding the refrigerant, the direction of circulation of the air around the evaporator, etc. The exact positions of the feed (F) and discharge (C)are variable, but the positions shown in Figure 3 are fairly typical. Figure 8. Speak with one of our process experts to find your solution today! The principal advantage of horizontal tube evaporators lies in the relatively small headroom they require. Separators provide a means for separating the vapour from the liquid with minimum liquid carry-over. Circulation is created by the difference in specific gravity between the bulk liquid and the heated liquid and vapor generated inside the tubes.The highest heat-transfer coefficients are achieved when the level is only about half-way up the tubes. Type of heat exchanger – Tube type, plate type, scraped surface etc. 2.5 (b)], Lesson 1. Our engineers can arrange laboratory and pilot-scale test to evaluate customer products and develop processes. Continuous washing by the bow waves minimizes fouling of the thermal wall, where the product or residue is most concentrated. The evaporator tube is called horizontal because the tubes are arranged horizontally. In the lower portion of the tubes, the feed is heated to its boiling point. The tubes may range from 1 in. The vapors from the rising-film pass aid in the distribution of liquid on the tubes, and increase the velocity of the liquid, which increases heat transfer. He earned his BChE at North Carolina State Univ., is member of AIChE, and is a registered professional engineer in North Carolina. Tubular evaporators are the first choice where they are applicable. Advantages of the short-tube vertical evaporator include: However, heat transfer depends greatly on the effect of viscosity and temperature, it is not for use with temperature-sensitive materials, and it is unsuitable for crystalline products unless agitation is provided. The rising-film and the falling-film evaporators are sometimes combined into a rising/falling-film evaporator to incorporate the advantages of both (Figure 6). To optimize the heat transfer and maintain low bulk temperatures, plate evaporators are often operated under reduced pressure. The liquid is in the tubes and the heating medium outside the tubes. In such cases, the choice may be dictated by such factors as capacity, small batch production, past plant experience, available space, operator requirements, utility requirements, maintenance required, and/or cost. The long-tube falling-film evaporator (Figure 5) is a variation of the long-tube rising-film evaporator, in which the equipment is turned upside down so the tubular heat exchanger is on top of the vapor/liquid separator section.Feed enters at the top of the evaporator, where specially designed distributors evenly distribute the feed into each of the tubes. It may require more cleaning time, but it is typically a low-maintenance system. In addition, staging or vapor recompression for energy recovery are not practical. Good quality horizontal tube evaporator from horizontal tube evaporator manufacturer, Buy horizontal tube evaporator online from China. Machine can expansion 6Tubes, 8Tubes or more tubes in one shot. When this type of evaporator is used with a product that can deposit salt or scale, it is customary to operate with the liquid level appreciably higher than optimum and usually above the top tubesheet (3). horizontal tube evaporator. The properties of the concentrate may change as the solids concentration increases. The increased velocity of liquid in the tubes (typically in the range of 4–10 ft/s) may also reduce or eliminate any potential fouling, thereby maintaining capacity and reducing downtime. One of the more useful types of evaporators for difficult-to-handle materials is the agitated thin-film evaporator(Figure 8). Flash Evaporation. This article first explains the process requirements that an evaporator must meet, and discusses the critical operational and product characteristics and their effects on evaporator selection. The majority of thin-film evaporators in operation today are of the vertical, cylindrical, fixed-clearance rotor design.The feed enters the unit above the heated zone and is distributed evenly over the inner circumference of the body wall by the rotor (Figure 9). Evaporation differs from drying in that the residue is a flowable liquid instead of a solid. 2.5 (a)] , [Fig. 2. The Hairpin Tube End Horizontal Expander machine is suitable for coil tube both Hairpin Tubes End at Left Angle or Right Angle direction (see below photo) and Straight Tube End . The falling-film evaporator is a variation of the long-tube rising-film design, in which the tubular heat exchanger is on top of the liquid/vapor separator. 5. Any increase in the viscosity of the concentrate will reduce the overall heat-transfer coefficient. Evaporator tabung horizontal. To investigate the falling film heat transfer coefficient, evaporator is designed with horizontal tubes arranged in staggered manner. Horizontal tube evaporators are not suitable for salting or scaling liquids, and they have smaller capacity than other evaporators. This can be accomplished by a combination of minimizing the volume of product in the evaporator at anyone time, minimizing the time in the evaporator, and reducing the product’s bulk boiling temperature by operating the evaporator at reduced pressures. The heat is supplied by condensation of steam in one side of a metal surface and the liquid material to be evaporated on the other side. In case of horizontal film evaporation the liquid to be vaporised is distributed evenly on the top of a horizontal tube bundle. Volatile components evaporate rapidly. Wholesale Horizontal Tube Evaporator ☆ Find 59 horizontal tube evaporator products from 22 manufacturers & suppliers at EC21. Progress,75(1), pp.52–58 (Jan. 1979). In a falling-film evaporator, it can improve the liquid loading at the bottom of the tube, allowing higher distillate-to-feed ratios. Many foods, pharmaceuticals, chemicals and resins are heat- or temperature-sensitive and require either low heating temperatures or a short residence time exposed to the heat, or both. horizontal tube evaporator working video youtube, Working Principles - Fallfilmverdampfer. Lack of wall wetting and fluid velocity may cause serious fouling and salting of solids on the heat transfer surfaces, causing reduced heat transfer and possible product quality degradation as a result of hot spots on the heating surface. In general, there must be enough liquid passing through the evaporator to keep the heat-ed walls wetted. Consideration must be given to the vapor velocity in the evaporator tubes and heating jackets. This website uses cookies to ensure you get the best experience on our website. Units consist of short tubes, 4-6 ft long, and 2-4 in. Explanation of horizontal-tube evaporator . Laju evaporasi air garam lebih kecil dibandingkan di wilayah air tawar, hal ini berkaitan dengan kenaikan massa jenis air. Heat-transfer coefficients can be improved and fouling reduced by placing an agitator into the tank(stirred batch). Selecting Evaporators for Process Applications, Be designed to effectively transfer heat at a high rate with minimum surface area to be cost-effective for installation,operations and maintenance, Effectively separate the vapor from the liquid concentrate, Meet the conditions required by the product being processed, Produce a product that meets the required quality, Be energy efficient, where possible making effective use of steam with multiple-effect evaporation or vapor recompression, Minimize fouling of heat transfer surfaces, Be constructed of materials that are adequate to minimize corrosion, Suitable for liquids that have a moderate tendency to scale, since the product is on the tube side, which is accessible for cleaning, Fairly high heat-transfer coefficients can be obtained with thin liquids (up to 5–10 cP), Relatively high heat-transfer coefficients due to partial two-phase flow, Higher pressure drop through the tubes than in a falling-film evaporator, Hydrostatic head at the bottom of the tubes may increase product temperature and cause temperature-sensitivity problems, Power consumption for the circulating pump, A longer holdup of the product within the heating zone (3), Good heat-transfer coefficients at reasonable temperature differences, Generally not suited for salting or scaling materials, Good heat transfer over a wide range of services, Generally unsuited for salting or severely fouling fluids, Well adapted to evaporating heat-sensitive, viscous and foamy materials, Short residence time in the heated zone, measured in seconds to minutes, High heat-transfer coefficients due to the turbulence imparted by the rotor, Ability to handle high solids concentrations and viscous materials, Less product decomposition, resulting in higher yields, High recovery because of the “squeezing” of residues by the rotor (7), Purification of sensitive organic chemicals, such as natural oils, fatty acids, isocyanates, herbicides and insecticides, Concentration of foods and pharmaceuticals, such as lecithin, enzymes, fruit and vegetable purees, biological solutions, vegetable and plant extracts, and fermentation broths, Recovery of valuable resources from waste streams, such as solvents from paints, purification of used motor oil, glycerin from crude streams, and volume reduction of inorganic salt streams, Devolatilization of thermoplastics, acrylic resins, phenolicresins, silicone polymers, polyester and nylon, hazardous waste minimization for disposal,e.g.,radioactive waste stream, Start-up time for the process to maximize onstream time and minimize loss of product during process stabilization, Minimum hold-up of product at shutdown to minimize loss of product, Short residence time to minimize product loss due to degradation, Prevention of fouling that causes loss of onstream time for cleaning, The ability to squeeze valuable products from the concentrated residues where the distillate is the product, which reduces waste and the need for recycle (or a second stage) to recover additional product, Ability to strip volatiles to low levels in the concentrate (mass transfer) where the concentrate is the product, McCabe, W. L., and J.C. Smith,“Unit Operations of Chemical Engineering,” McGraw-Hill, New York, NY, pp.533–538 (1958), Kern, D. Q., “Process Heat Transfer,” McGraw-Hill, NewYork, NY, pp. Fig_2.1.SWF, A simple unit, not used to a great extent on new installations, is the horizontal tube evaporator. 2. The horizontal tube evaporator is the only type of chemical evaporator in which the heating medium is inside the tubes. At some distance further up, bubbles form on the tubes and boiling begins, increasing the linear velocity and the rate of heat transfer. A batch evaporator is one of the simplest designs. The simplest, and one of the oldest, designs is the batch evaporator (Figure 1). Loss of film integrity, as it can occur at strongly reduced feedrates in falling film evaporators but also in vertical thin film evaporators, is not possible in horizontal thin film evaporators. Tubes are rolled between two tubesheets and steam is introduced as shown in Figure 3. Circulation and heat transfer in this type of evaporator are strongly affected by the liquid level (3).Boiling in the tubes induces circulation past the heating surface. In the next evaporator, the heating chamber is formed by the horizontal tubes, which are supported by two plates. In natural circulation units, circulation of the liquid is brought about by convective currents arising from the heating surface. Vertical shell-and-tube heat exchanger, with a laterally or concentrically arranged centrifugal separator. A properly designed evaporator must, at a minimum: Critical operational and product characteristics of the solution to be evaporated have a major effect on the selection of the evaporator type most suited for the application. Batch evaporation is not well-suited for temperature-sensitive products. The volume held in the plate evaporator is very small compared to the large available heat-transfer surface. They have very low headroom. The vapour is removed after last calandria by condensation either by condensing on water cooled surfaces or by condensing through direct contact with cooling water. The simplest evaporator as shown in following figure, consists of an open pan and kettle in which liquid is boiled. Product characteristics such as high viscosities or heavy solids gives some direction. The long-tube vertical, or rising-film, evaporator (Figure 4) is one of the most widely used tubular evaporators. Reduction below the optimum level results in incomplete wetting of the tube wall,with a consequent increase in fouling tendency and a rapid reduction in capacity. Eng. Advantages of an agitated thin-film evaporator are: A disadvantage is its higher cost compared to standard evaporation equipment. (Fig. These evaporators are inexpensive and simple to operate, but the heat economy is poor. One principal use of the short-tube vertical evaporator is the concentration of sugar cane juice. 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