Molecular distillation equipment
Molecular distillation is also called short range distillation. It is a relatively new liquid-liquid separation technology which has not been widely used in industrial production. Its application can solve a lot of problems which the conventional distillation technology can not solve.
Compared with conventional distillation, molecular distillation has the following characteristics:
1. Ordinary distillation is at the boiling point temperature for separation operation: molecular distillation as long as the hot and cold between the two sides to reach a sufficient temperature difference. It can be separated at any temperature. Thus, the operating temperature of molecular distillation is much lower than the boiling point of the material.
2. Common distillation has bubbling. Boiling phenomenon: molecular distillation is the free evaporation of liquid film surface. The operating pressure is very low, generally on the order of 0.1-1Pa, and the heating time is very short. Generally only 10 seconds to tens of seconds.
3. Evaporation and condensation in ordinary distillation are reversible processes. The liquid and gas phases are in a dynamic phase equilibrium, while in the molecular distillation process. Molecules escaping from the heating surface fly directly onto the condensing surface. There is no theoretical possibility of returning to the heated surface. So molecular distillation doesn't have anything that's hard to separate.
A complete set of molecular distillation equipment mainly includes: molecular evaporator, degassing system, feeding system, heating system, cooling vacuum system and control system. The core part of the molecular distillation device is the molecular evaporator, which has three main types: (1) falling film: the early form, simple structure, but because of the thick liquid film, poor efficiency, rarely used in the world; (2) Scraping film type: the liquid film formed is thin and the separation efficiency is high, but the structure is more complex than falling film type; (3) Centrifugal: centrifugal force film formation, thin film, high evaporation efficiency, but complex structure, vacuum sealing is difficult, high manufacturing cost of equipment. In order to improve the separation efficiency, it is often necessary to use multistage series to achieve multistage separation of different substances.
1. Falling film molecular distiller
The device adopts gravity to make the material on the evaporation surface into a liquid film. When the material is heated, the evaporated material can condense on the condensation surface in the opposite direction. Falling film device is an early form, simple structure, thick liquid film formed on the evaporation surface, poor efficiency, rarely used in many countries.
2. Scraping membrane molecular distillation device
In the late 80s, the research on scratch membrane molecular distillation device and process application was carried out. It takes gravity to make the material on the evaporation surface into a liquid film falling way, but in order to make the liquid film thickness on the evaporation surface is small and evenly distributed, a rotating scraper made of hard carbon or polytetrafluoroethylene is arranged in the distiller. The scraper can not only make the downstream liquid layer get sufficient agitation, but also accelerate the evaporation surface liquid layer renewal, so as to strengthen the heat and mass transfer process of the material. Its advantages are: the liquid film thickness is small, and flow along the evaporation surface; The residence time of the distilled material at the operating temperature is short, the risk of thermal decomposition is small, the distillation process can be continuous, and the production capacity is large. The disadvantages are: the liquid distribution device is difficult to perfect, it is difficult to ensure that all the evaporation surface is uniformly covered by the liquid film; Liquid flow often occurs tumbling phenomenon, the resulting fog is often splashed on the condensation surface. However, due to the relatively simple structure and low price of the device, most of the laboratory and industrial production, the device is adopted.
3. Centrifugal molecular distillation device
The device sends the material to the center of the high-speed rotating table, and expands to form a film on the rotating surface, while heating evaporation, so that it condenses with the opposite condensation surface, the device is an ideal molecular distillation device. But compared with the other two devices, it requires a high speed rotary table and a high vacuum sealing technology. Compared with the scraping molecular distiller, the centrifugal molecular distiller has the following advantages: due to the high speed rotation of the turntable, extremely thin liquid film can be obtained and the distribution of liquid film is more uniform, and the evaporation rate and separation efficiency are better; The heating time of the material on the evaporation surface is shorter, which reduces the risk of thermal decomposition of the heat-sensitive material. Material handling capacity is larger, more suitable for industrial continuous production.
Alcohol distilling equipment
Features: First, energy saving. Adopt high efficiency and low resistance plate, reduce the kettle temperature, appropriate reflux, establish a reasonable use of energy at all levels of distillation process; Try to use instrument control or microcomputer automatic control system, so that the equipment in the best load state.
Second, the production intensity is high. In ORDER TO IMPROVE THE VAPOR-LIQUID FLUX OF UNIT COLUMN SECTION, ESPECIALLY IN THE DESIGN OF MASH COLUMN, MORE ATTENTION SHOULD BE PAID TO THE RELATIONSHIP BETWEEN VAPOR-LIQUID RATIO. One of the ways to make the equipment more compact, production intensity and processing capacity can be improved, the use of high efficiency tray instead of the original old tower school (tower body is not moving).
Third, the sewage performance is good. While MINIMIZING THE CONTENT OF FIBER IN MATURE MASH, THE EQUIPMENT SHOULD ALSO BE CONSIDERED TO adapt TO the distillation of fermentation broth containing solid material, SO as TO minimize The Times of STOPPING the cleaning tower.
Fourth, the amplification effect of the tower should be fully considered. Especially for the tower equipment with an annual output of more than 15,000 tons, because the tower diameter is more than 1.5 meters, it is necessary to take active and advanced measures for the large-diameter tower equipment to reduce the reduction of separation efficiency.
Fifth, the structure is simple and the cost is reduced. The new type tray with simple structure and high efficiency is selected when the process conditions permit.
Principle of device
The device is SUITABLE FOR the recovery of dilute alcohol in pharmaceutical, food, light industry, chemical industry, etc. It is also suitable for the distillation of methanol and other dissolved coal. According to user's requirements, the device can be 30. Around dilute alcohol distilled to 90. - 95. Alcohol, finished alcohol strength requirements again high. The reflux ratio can be increased, but the yield will be reduced accordingly.
Adopt high efficiency stainless steel corrugated packing. The distillation tower body is made of stainless steel, thus preventing the phenomenon of iron filings blocking the packing and prolonging the service life of the device. All parts of the equipment in contact with alcohol, such as condenser, pressure regulator tank and cooling snake tube, are made of stainless steel to ensure that the finished alcohol is not contaminated. The distillation kettle adopts detachable U-shaped heating tube, which can be removed out of the kettle during maintenance to facilitate the cleaning of the outer wall of the heating tube and the inner wall of the distillation kettle. This device can be intermittent production, also can be continuous production.
