SU946569A1 - Film evaporator - Google Patents

Description

(54) FILM STEAM DEVICE

  . .

The invention relates to evaporation technology, and more specifically to evaporation devices and evaporators, operating at low heat fluxes, and can be used to concentrate solutions of food and other products. ;

Evaporators are known with an ascending two-phase flow during its movement in the annular channels and evaporators with a descending film of the evaporated solution in countercurrent with the resulting secondary

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The closest to the proposed design and the effect achieved is a film evaporator, containing a vertical cylindrical body, tube sheets, installed in a body, boilers: fixed in tube sheets, step hollow inserts placed in pipes, and nozzles for input and output of the vaporized solution, heat carrier and secondary steam 2,

A disadvantage of the known evaporator apparatuses is that when the inserts are closed, the inner space of the inserts is rationally used, for example, to organize a natural

circulating evaporated liquid. In film-type apparatuses without special film flow organizers, uniform irrigation of heating pipes is difficult. Irrigation of pipes with a different distance from the injection of water (non-adjacent irrigation) leads to the fact that the liquid is cooled and the pipes are irrigated with underheated liquid to the state of saturation with liquid. At the same time, the boiling tube has a considerable economizer section with a low heat transfer rate. It is impossible to evaporate scale liquids with film organizers. Last boil.

The purpose of the invention is to intensify the process by reducing the hydrodynamic depression and organizing the film-ring evaporation mode.

The goal is achieved by the fact that in a known film evaporator apparatus comprising a vertical cylindrical body, tube sheets,

Claims (2)

 boiling tubes installed in the housing, fixed in tube grids, stepped hollow inserts placed into the pipes, and fittings for the inlet and outlet of the evaporated solution, heat carrier and secondary steam, the stepped inserts are made with a constant length of wall thickness with open upper and lower ends. Additionally, the upper ends of the inserts protrude above the tube sheet. The creation of a stepped annular channel makes it possible to maintain a high flow rate of a unidirectional two-phase film flow and to achieve high values of the heat transfer coefficient along the entire length of the pipe with small gi; equilibrium resistances. The floor insert into the pipe allows, under different thermal conditions and hydrodynamic conditions of the apparatus, for example, increasing the level of liquid over the tube sheet, to close. Circulation and ensure the normal operation of the steam generating channel. In this case, the inserts act as descending pipes. The adjacent location of the lifting and descending steam generating channels allows for uniform irrigation of all standpipe without the use of film flow organizers. At the same time, it is also important / that liquid enters the desiccant boiling tubes at the stage of saturation. The drawing shows the apparatus, about the longitudinal section. The evaporator comprises a housing 1, fittings 2, a tube grid 3, boiling pipes 4, stepped hollow inserts 5, held on brackets 6 and centered using clamps 7. The insert is placed in the heating pipe 8, which is fixed in the upper 3 and lower 9 tube sheets. The bottom cover 10 has a fitting 11 for evaporating solution. During 5 hours of operation of the apparatus, the initial solution in a state of saturation supplies it to the supra tube space. During steam formation in boiling tubes 4, due to the higher vapor content of the biphasic vapor – liquid mixture, the flow rate and the biphasic flow occur in the annular channels and the film downstream, antidirectional with the vapor, the liquid flows in the tubes without inserts 5. The evaporated solution is discharged from the subtubing space. Tests of the industrial model of an evaporator make it possible to find optimal operating conditions characterized by a high heat transfer coefficient and a hydrodynamic depression mesh; confirm the feasibility of using the device at low and medium heat fluxes, which is advantageous for the operating conditions of multi-unit evaporation stations and the use of low-grade secondary thermal resources to establish that the adjacent symmetric arrangement of coaxial stepped hollow inserts in the part of the boiling tubes and the semi-overturned film mode of descending steam generating channels allow to create circulation in the apparatus of motion boosters and to organize a fairly uniform irrigation of the standpipes with the SRI thermal saturation of the solution is evaporated; reduce the size of the apparatus and reduce the residence time of the solution in the high temperature zone, i.e. preserve the quality and quantity of the processed product, etc. Claim 1. Film evaporator comprising a vertical cylindrical body, tube grids installed in the hull, boiling tubes fixed in tube grids, stepped hollow inserts placed in tubes, and fittings for inlet and outlet of the evaporated solution, heat carrier and secondary vapor , characterized in that, in order to intensify the process by reducing the hydrodynamic depression and organizing the film-ring evaporation mode, the step inserts are made with a constant thickness a wall with open upper and lower ends. 2. An apparatus according to claim 1, characterized in that the upper ends of the inserts protrude above the tube sheet. . Sources of information taken into account in the examination 1.Patent Czechoslovakia 119220, cl. 12a, 2, 1966. 2. US patent I 2117337, cl. 159-27, 17.05.38.