Vacuum distillation unit introduce _

vacuum distillation is to make some of high boiling point compounds compounds boiling, reduce the pressure of compounds when boiling, but a lower pressure to the compound vapor pressure ( In a certain temperature) Began to boil, compounds, can be carried out on distilling technology, and in the form of vacuum carburetor is common in the laboratory. Vacuum distillation process used in the petroleum chemical industry is relatively common, compared with the distillation under atmospheric pressure, it has many characteristics, lower the boiling point. Decomposition polymer risk is small, can low temperature treatment; Easy to heat, heat loss small; The oxygen in the air, the influence of water vapor composition such as reducing xiang to volatility; Balance changes ( Such as azeotropic point disappear)

according to the different distillation system operating pressure, vacuum distillation can be divided into: (1) common vacuum distillation process of vacuum distillation, mostly in the operation of more than 104 pa pressure range. Mechanism of vacuum distillation and atmospheric distillation, atmospheric distillation unit form basically is available. (2) crude vacuum distillation pressure range of 1. O*104Pa- 2. 7 x102pa, gas flow of viscous state. In this pressure range for distillation operation is easy to implement. (3) low pressure vacuum distillation range of 2. 7*102Pa- 1. OPa gas nearly transition flow state at this time, for the vacuum distillation device type selection, design, manufacture, installation, operation and so on all have more strict requirements. (4) the accurate molecular distillation pressure range of 1. 0 - 1. 0 * 10 - 2 pa, at this point, the gas molecules and the distiller size close to the mean free path, gas was in transition flow state. 5. Molecular distillation operating pressure in 1. 33 * 10 - Under 2 pa. In the molecular distillation or quasi molecular distillation device, the flow of the gas for the free movement of molecules, that is to say, you can ignore the other molecular collision and interference of the system, at this point, the distillation process governed by evaporation from the liquid surface. Vacuum distillation unit: 1, intermittent distillation unit batch vacuum distillation device, is widely used in the lab and small batch production. Its main parts as follows: (1) retort for external pressure vessel, generally USES coil or model of the heat exchanger, heat with steam or oil. In order to improve the heat transfer condition, most of the tank with agitator, also can set up raw material preheater or forced circulation heater. Raw material heating, degassing and distillation processes are conducted in the tank. (2) usually choose column condenser tube ( The shell side of the vapor go) , rotary plate ( Steam way through) Condenser. Condenser and distillation tank is normally set separately. But sometimes it can be directly on the top of the distillation tank constitute an organic whole. Due to out of gases from the condenser (3) well including condensate temperature steam and condensate gas, some of the vacuum pump is not suitable for pumping the steam. In order to protect the vacuum water pump and to capture of distilled from material, machinery trap, trap or adsorption at low temperature is often used to trap. A mechanical trap type centrifugal ( Whirlwind, swirl plate) Type, collision, Baffle type, umbrella, baffle plate, etc. ) And the air filter type ( Wire mesh filter, dry filling type, etc. ) 。 2, yan straight distillation device such device between batch distillation device and distillation device, compared with the intermittent, it is not for a long time high temperature heating parts, high safety of heat. In addition, the capacity of the device is small, can carry on the continuous operation regularly, and have a certain degree of distillation effect. Due to its itself subject to the conditions of preheat and residence time, therefore can only be used for relative volatility is bigger, better separability. Commonly used for degassing, dewatering, solvent and deodorization etc. 3, atmospheric continuous rectification column (1) plate column used in a variety of plate tower, all can be used in the vacuum distillation. In order to reduce the pressure loss, and use effect and has no holes more pressure drop less plate type, such as injection, passing through grid, etc. (2) packing vacuum distillation tower with packed tower. Commonly used in a variety of normal pressure filler tower packing can be used in vacuum distillation. Because of pall ring packing, corrugated wire mesh packing and rolling orifice plate corrugated packing pressure loss is very small, more suitable for packing of the vacuum distillation. (3) thin film in the thin film tower tower, between liquid and vapor continuously carrying on the evaporation and condensation, which brings certain rectification effect. (4) rotating tower in order to reduce the pressure loss of plate tower and packed tower, ensure good gas-liquid contact and improve the effect of distillation, rotary vacuum distillation is presented. The general structure is cooled by a rotating with the inner cylinder and a fixed a mix of heating of the outer cylinder. Rotating cylinder speed reaches hundreds or even thousands of revolutions per minute, the effect of the centrifugal force, the condensate to fly to outer cylinder, evaporation in the resume, so repeatedly evaporation condensation for rectification. In order to strengthen the mixing effect of liquid membrane, and on the inner surface of the close to the outer cylinder set mixing blade or brush structure, etc. Rotating tower is mostly used in laboratory scale and can be used for 1 pa high vacuum distillation apparatus.