SU789715A1 - Apparatus for determination of melt crystallization temperature - Google Patents

Description

as well as low measurement accuracy due to the lack of a clearly defined horizontal section on the cooling curve, which corresponds to the crystallization time of the sample.

The purpose of the invention is to improve the accuracy of measuring the crystallization temperature and shorten the cycle time.

This goal is achieved by the fact that the device contains a node of an adjustable heat sink, located in a crystallization chamber, made in the form of two tubes, bent in the form of spirals and placed coaxially one inside the other.

The drawing shows the structure of the device.

The device contains a sampler 1, immersed in a container 2 with a melt and made in the form of hollow coaxial cylinders 3 and 4. The outer cylinder of the sampler 1 is connected by a cooling air supply pipe 5, and the inner cylinder is connected to an air supply pipe 6 for blowing. The sensing element 7 is located in the inner spiral-shaped tube 8 of the heat sink assembly. The heat sink assembly is made in the form of two coaxially arranged spiral-shaped tubes 8 and 9 located in the crystallization chamber and connected by supplying tubes 10 and 11 to a source of cooling air. Pressure gauges 12 and 13 are installed on the supply pipes 10 and 11 to control the pressure of the cooling air supplied to the heat sink assembly. The crystallization chamber of the sampler 1 is the lower internal cavity of cylinder 3, covered by cylinder 4 and filled with water.

In the initial state, sampling 1 and the heat sink assembly are disconnected from air sources (not shown). The cavities of the inner outer cylinders 3 and 4 are filled with melt. At the beginning of the measurement cycle, cooling air is supplied through the tube 5 through the tube 5, under the action of which the melt is displaced from the outer cylinder 4 into the process tank 2 and subsequently the air flows directly into the volume of the process tank 2. Simultaneously with. By this, cooling air through pipes 10 and 11 is fed into the spiral-shaped tubes 8 and 9 of the regulated heat sink assembly (conventionally shown by solid lines). At the same time, the process of cooling the sample located in the crystallization chamber begins. The design of the heat sink assembly, in which the diameter of the inner spiral tube is 0.2-0.3, and the outer diameter, 0.6-0.7 diameter of the crystallization chamber.

provides the creation of three cooling zones within the volume of the crystallization chamber: the inner (in the inner region of the spiral tube 8), the middle region (between the inner and outer tubes 8 and 9) and the outer region (between the tube 9 and the walls of the inner cylinder of the sampler 3). which have approximately the same heat sink conditions. Between these three zones, as well as within each zone, there is an intense heat exchange and convective mixing of the melt, which leads to uniform cooling of the melt sample in the volume of the crystallization chamber. Rav isomeric cooling of the sample is necessary so that the crystallization process starts simultaneously in the entire volume of the crystallization chamber. In this case, the heat of transformation is released simultaneously from the entire sample of the melt, which gives a strictly horizontal view of the crystallization shelf on the cooling curve recorded by the recorder.

The sensor is adjusted according to the type of crystallization shelf on the cooling curve, the cooling air pressure in the supply tubes. 10 and 11 are chosen so as to obtain a strictly horizontal and sufficiently long shelf by which the crystallization temperature of the melt is then determined.

When the temperature of the sample melts below the crystallization temperature,. A control device (not shown) stops the flow of cooling air into the cavity of the outer cylinder 4 and into the tubes 8 and 9 of the heat sink assembly. The cavity of the outer cylinder 4 is filled with melt from the process tank, and the heating and recrystallization of the melt sample takes place. When the sample temperature reaches higher than the crystallization temperature, a pulse of air is blown into the cavity of the inner cylinder 3 through the tubes 6, under the action of which the melt is displaced into the tank 2, replaced by a new sample of the melt into the inner cylinder 3, after which the whole measurement cycle is repeated first .

The unit for automatic connection of the proposed device to the sources of cooling air is realized on the basis of a KEP-12U command electropneumatic device, a pulse shaper, and a KSP-4 secondary device.

The heat sink assembly of the proposed device allows you to set the optimal heat sink mode — from the inside of the crystallization chamber — by appropriately adjusting the cooling air pressure using gauges 12 and 13, at which time

Claims (1)

Claim A device for determining the crystallization temperature of a melt, consisting of a sampler made in the form of coaxial hollow cylinders, the inside of which is connected to a source of air for purging, and the outside with a source of cooling air, a heat sink unit located in the crystallization chamber and a heat-sensitive element, distinguishing - with the fact that, in order to improve the speed and accuracy of measurement, the heat sink unit is made in the form of two tubes, bent in the form of spirals and placed coaxially one inside the other goy, the diameter of the inner coil is 0.2-0.3, 0.6-0.7 and the outer diameter of the crystallization chamber and the temperature sensing element is disposed within the inner coil.