Centrifugal spray drying technology in the late 1950s began to use in the domestic dairy industry, more than 40 years of history. At present there are about 5% of the dairy industry of manufacturers to adopt this technology. It promote the rapid development of China's dairy industry has played a positive role. 1 centrifugal spray drying of the birth of China's dairy industry, the first application of spray drying technology is "pressure" and "two-fluid" technology, but because of technical limitations and scale of production and other various factors, only horizontal, level, more in the form of jets, its ability to evaporate mostly in the 250kg / h or less. The mid-1960s, Anderson dairy plant installed an evaporation 350kg / h horizontal pressure spray drying equipment, the nozzle to 7; 1967 Assistance to Albania, spray drying equipment provided imitation dairy factory in southern Beijing imported from Japan in 1965 evaporation 350kg / h double nozzle, horizontal, pressure spray dryer requires evaporation 150kg / h, also dual nozzle; milk late 1960s Shanghai Jing three plants for the first time installed a vertical pressure spray dryer, which evaporation is 250kg / h, the nozzle still have not less than three. This was the emergence of multi-nozzle hot, is primarily a false theory prevailed. Many people believe that the nozzle aperture can not exceed a certain value, otherwise, the material can not be atomized. This small equipment capacity at that time, the inevitable result is a multi-nozzle, the production of small diameter nozzle, the smallest nozzle diameter is only 0.5mm, which gives the production operation, management caused many problems, but mainly so that small particles of milk, red poor tone, color, the state is not an organization of users. To solve this problem, many manufacturers, research institutes, universities in many ways to find good brew instant milk production ", have a" two-stage drying method, "" lactose recrystallization method "and the trial production, But the end result of the high cost, not suited to large-scale continuous production can not be promoted. At the same time, the emergence of centrifugal spray drying technology, and with some development, mainly due to lower time to come up with indigenous centrifugal sprayer speed, only 5000r / mim) around, because the line speed is low, the discharge of milk powder particles, prepared and better than pressure spray products in the market is relatively popular with users until the 1970s 末离 heart spray-dried milk production in a market dominated by At that time a representative of several dairy milk factory is the Songhua River, Chahayang dairy plant, dairy plant west of Beijing, Zhao Er dairy factory. 2 centrifugal spray drying of the recession in 1980 Heilongjiang Dairy machinery plant design evaporation 250kg / h single-nozzle vertical pressure spray dryer ten, 1982 in Taylor County dairy put into normal operation, after which the new, expanded dairy plant using centrifuge drying technology gradually reduced, some of the old has been using a centrifugal spray technology plant, expansion started using pressure spray technology, manufacturers do not consider the two techniques simultaneously inconvenience of management, such as Fuyu County milk crystal factory, Zhaodong dairy plant, dairy plant west of Beijing, Hulan dairies, dairy Songzhan . and some centrifugal spray technique has been used for many years in the old factory, the new pressure spray drying equipment installed after the original centrifugal spray drying equipment deactivate or simply removed, as Zhaodong dairy plant, dairy plant west of Beijing; since the late 1980s , a "centrifugal" to "pressure" phenomenon, the author of successful transformation has rich dairy, Songhua dairies, dairies and waves Songzhan dairy ranch. The emergence of these phenomena, indicating that people have come to realize "centrifugal spray" and "pressure spray", centrifugal spray drying technology in China's dairy industry has been shaken in the market, ten pressure spray drying technology has an absolute advantage, we can say "centrifugal spray" has begun to decline in China's dairy industry. Both methods pros and cons of the debate has been rarely heard, no longer hear the "centrifugation" milk good positive statement than the "pressure method" quality. This change of generation, there are many factors to analyze the reasons. The main are the following : (1) theoretical misunderstanding Denmark K · Maas 托思 with the "Spray Drying Handbook" clear that centrifugal spray drying method is suitable for the production of fine particles of the product some people because we made no high-speed centrifugal sprayer. atomized leaving a bad case of larger particles produce milk mistaken advantage centrifugal spray (2) centrifugal spray drying equipment set design non-standard from 50 - 80 years, China's dairy industry uses centrifugal spray drying equipment Almost all out of "self-taught expert" hand, there are no standard design for less investment, fast horse, centrifugal sprayer mostly "soil made" hot air dispenser variety, into the wind uneven, can not be adjusted, there are " coke powder "problem, not a few to reach design capacity, resulting in and before the process is not complete. (3) The main raw material for the production of raw milk is characterized by the nature of the milk is fresh milk, which additives such as sugar, milk powder extinction, milk and other substances are soluble, and will not form a milk mixed precipitation, the concentrated viscosity is not high, the material is also very suitable for pressure spray dried, not only with centrifugal spray ten dry. (4) as a single nozzle vertical pressure spray equipment in the early 1980s after a single nozzle vertical pressure spray drying equipment appeared, and soon to be widely used. Due to the large nozzle diameter, the particles reach or exceed its powder milk centrifugal spray particles reconstitution of the two products is almost the same, centrifugal spraying milk reconstituted good advantage is no longer unique, pressure spray drying milk punch tone poor argument has been to name. (5) lack of centrifugal spray drying method and vertical centrifugal spray drying pressure spray drying method, with the following deficiencies: I. Low evaporation intensity. Centrifugal spray atomization tower after material difference in the trajectory and hot air in the tower trajectory, causing material and hot air heat and mass transfer time is shorter than the vertical pressure spray dried to make the unit available space is less than the vertical pressure evaporation capacity Spray drying also reduces evaporation intensity, according to the measured evaporation strength is generally ≤3kg / h.M3, including recent years the introduction of centrifugal spray drying equipment. Evaporation intensity vertical pressure spray drying equipment generally ≥5kg / h.M3, which makes the effective volume of centrifugal spray drying tower with capacity of more than about a vertical pressure spray drying tower big 80%. Due to the low evaporation intensity, so that the volume devices increases, leading to a series of problems:. A material consumption of manufacturing equipment and more, the cost of equipment to improve, with the ability to centrifugal spray drying equipment than the vertical pressure spray drying equipment costs by 20 about%. b. Since the device is relatively large, to the manufacture, transportation, installation are added to the difficulties. c. Large space to install the equipment, installation of equipment of the plant also need to be increased, which increases the plant civil engineering investment. d. Equipment operation and convenient cleaning after work, had to increase the number of attachments, sweeping powder devices such as centrifuges can lift and lifting devices. Ⅱ. More powder tower wall. As the material centrifugal spray drying atomization parabolic trajectory, plus the hot air into the tower has a rotational force, the tower complete (including overhead) sticky powder and more, especially the production of sugar, powdered milk, baby formula and other products more serious. Heilongjiang dairy introduce Denmark "Nile" centrifugal spray drying equipment, tower inner diameter of 7.4m, continuous production of infant formula milk powder II, month, pink sticky wall thickness of 80mm or more, the plant thoroughly cleaned once a month, sweeping down to this part of the powder can no longer serve as grades. Ⅲ. Products have been contaminated with oil possible. Atomized material centrifugal sprayer from the structural requirements must be installed in the center of the hot air overhead dispensing device. Due to high ambient temperature, high-speed rotating centrifuge, lubricating and cooling needs, the lower end of the Seals, seals once damaged, oil will leak into the tower of the product in operation, contamination of the product, but also in the operation hard to find oil spills. Ⅳ. Milk storage period is short, fat susceptible to oxidation. Centrifugal spray drying production of milk powder contains more air, during storage, the milk fat powder readily oxidized by air within that storage period is shortened. Reconstruction 3 centrifugal spray drying equipment from the milk product structure characteristics of our point of view, China's dairy industry, milk production in the best drying equipment, it should be said that the vertical pressure spray drying equipment. Practice has been proved that if the leadership of centrifugal spray drying equipment unit is also aware of this, it would be easier to handle. Because, quot; centrifugation ", to" pressure "is feasible, it is very easy, and also has tangible benefits for feasibility in recent years there have been four dairy plants, the success of the centrifugal pressure spray dried instead of spray drying. put into normal operation, this is because there are the following reasons: (1) the same points can be universal "centrifugal" and "pressure" of two spray drying the same basic principle, all materials are atomized, and the hot air in an instant complete heat exchange and mass transfer, dried material and air separation unit for product separation. Both belong to and flow drying, atomized material and hot air drying are both top-down with the completion of the movement in the tower Most of the same process ancillary equipment, can be common as the same air filter, air heater, into the fan, exhaust fan, filtered and concentrated milk powder unit cylinders and so on, can be common. These same parts, such as the original design, selection correct and reasonable, the transformation may not need to make any changes maintain the status quo can be common. (2) less distinct points, easily transform nebulizer not the same, and the pressure centrifugal spray dryer is the fundamental difference between the different materials atomization, the former is used High-speed rotation of the centrifuge atomizing the material, the latter is by high-pressure pump pressure, the atomizing nozzle material. Different hot air distributor, because the two different nebulizer, hot air into the tower dispenser is different. centrifugal spray method using VOLUTE based, multi-use pressure spraying baffled, which is simple structure, manufacture, installation, adjustment of the inlet of uniformity than the former easy and simple. column diameter and effective height is different, because the two mist from the tower trajectory dissimilar diameter centrifugal column diameter compared with the same ability to be more pressure column was 35%; and the effective height of the former than the latter lower the effective volume of more than 40% different due to the different intensity of both evaporation, centrifugation tower with capacity. effective volume than pressure column effective large volume of more than 70% different from the effective height of the tower to the roof, centrifugal centrifugal spray tower because of the need hoisting machine, the effective height of the tower to the roof of more than 3m, and the pressure column generally no more than 2m. (3) distinct point analysis nebulizer, hot air distribution fetal two different points, the transformation can be resolved as long as the replacement for the column diameter and effective height is different than the pressure centrifugal column diameter large tower, transformed the tower wall sticky powder ratio with the ability to tower less pressure about 50%, the top almost sticky powder; if the effective height of the tower centrifugal pressure column below the effective height limit requirements, you need to use a different effective height of the tower to the roof and take the appropriate high tower .. different effective volume, very useful for the transformation after transformation, can improve productivity efficiency centrifugal tower transformation after transformation, the pressure after the tower, in addition to solving the aforementioned four deficiencies, but also can receive the following benefits: (1) dry use Because of the overhead rate is almost non-stick powder, sticky powder tower wall is reduced by 50%, viscosity pink wall easily swept away, coke problem solving, dry milk is bound to a corresponding increase in the utilization. (2) increase the rate of product grades Since the settlement of the problem of coke powder, thereby eliminating a factor and product of impurities, related to the solubility index, prompting product grade rate has increased. (3) increase production capacity due to the effective volume of the centrifugal towers than the same general capabilities pressure column more than 70% greater, transformed evaporation intensity will increase, after replacing only surmise atomizer and hot air distribution, capacity can be increased by 20%; if appropriate adjustments to other ancillary equipment, and its capacity can be increased by 50% -100%, the practice has been demonstrated. 10t milk / shift centrifugal tower transformation in Heilongjiang Province rich dairy and Songzhan dairy milk reached 20t / classes; Lindian waves ranch dairy milk 5t / class centrifugal tower, transformed evaporation reaches 3l0kg / h, equivalent to milk treatment 12.4t / classes. (4) improve the operating environment centrifugation column is operated at a temperature of generally high tower, transformed into a pressure column, the operator can operate at the ground floor, the second floor surface temperature is lower than the overhead 20-30 ℃, or history of more . From - The above can be seen, the transformation of bamboo tower centrifugal two ways - a small alteration, which requires the ability to transform after no increase or a slight increase under the premise, only the replacement of the nebulizer and hot air distributor, invest no more than 5 million, downtime can be completed in a week or so. If the big transformation, requiring the ability to increase 50 percent or twice the investment is not more than 150,000 yuan; among discontinued approximately four weeks to complete. 

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