FI87735B - OVER ANCHOR ORDER FOR OPENING WITH GASER FRAON - Google Patents

Abstract

Liquids, especially spinning baths, are degassed by multi-stage expansion, heating of the liquid to be degassed, preferably by 1 DEG to 2 DEG C, being carried out between two successive expansion stages; in the case of aqueous liquids, this heating can be effected by waste energy. <IMAGE>

Description

1 87735

The invention relates to a method according to claim 1 for removing gases from liquids.

The invention further relates to a multi-stage pressure reducer according to claim 5 for use in carrying out the method.

Gases dissolved or insoluble in liquids are mainly removed from liquids under reduced pressure. Generally, liquids are sprayed for this purpose into a vacuum chamber. As a result of the pressure drop, a large part of the gases contained in the liquid are released. As the pressure decreases, more and more gas is released.

This process reaches its limit value; when the pressure prevails in the chamber is 20, at which the liquid boils at its current temperature. In order to efficiently degas the liquid, it is considered optimal that the degassed liquid be cooled to a temperature of 1 to 2 ° C below its boiling point at the respective pressure. At the same time, a large amount of liquid is evaporated. The steam generated in this case simultaneously acts as a carrier for the released gas. As a result, the partial pressure of the gas or gases released from the liquid is simultaneously reduced to the possible minimum of 30 under the prevailing conditions.

The disadvantage of this method is that the total amount of gas released from the liquid is included in the exhaust steam which carries the gas with it. This makes it difficult both to recover the gas or gases released from the liquid and to recover or continue the vapor phase.

2 87735 To assist in this situation, degassing of liquids is also carried out in two stages, and in particular when the pressure is reduced at a given vacuum after the liquid has been cooled to below 1 to 2 ° C below its boiling point. In this two-step process, the pressure of the gas-containing liquid is reduced in the first depressurization step to such an extent that a significant part of the gases contained in the liquid is released without the liquid still significantly evaporating. This then means that the amount of gas carried by the cooling steam in the next second depressurization step is substantially lower than in the one-stage process, so that the condensation of the steam generated in the second depressurization step can take place under much more favorable conditions and especially in much smaller plants.

To clarify the circumstances, the removal of gas from spinning solutions used in the staple fiber industry is explained.

20 In addition to a considerable amount of air, such spinning solutions also carry hydrogen sulphide and carbon disulphide in large quantities. Both hydrogen sulphide and carbon disulphide must be virtually completely removed before the spinning solution is returned to the spinning process or the spinning solution is removed.

25 The gases must therefore be carefully removed from the spinning solutions before the solutions can be removed or returned. Generally, the vapors removed with these gases must be removed. Given the relatively large amounts of spinning solution used in existing plants, this means in practice that the optimal cooling of the spinning solution for degassing at only 1 to 2 ° C corresponds to a process heat loss of 1 to 3 tons of steam / h per spinning machine.

In view of this state of the art, it is an object of the invention 35 to provide a method and an apparatus for carrying out this method, whereby the same removal efficiency as known methods is achieved with lower energy consumption.

To solve this object, the invention provides a method having the features of the characterizing part of claim 1. The equipment used to carry out this method, in particular the multi-stage pressure reducer, has the features set out in the characterizing part of claim 5.

The method and apparatus according to the invention are preferably used for the removal of gases from spinning solutions used in the staple fiber industry.

Thus, the essential idea of the invention is to carry out a multi-stage degassing of liquids, in particular dilute aqueous solutions, in at least three stages, so that the energy required for cooling at Heating to 2 ° C can take place with low-cost process heat that can hardly be used elsewhere, for example with exhaust steam from an evaporator or some other low-energy exhaust steam, for which cooling water must otherwise be used for its final compaction.

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According to an embodiment of the invention, this three-stage degassing process is preferably carried out by degassing the liquid in a first stage under reduced pressure, where significant evaporation of the liquid does not yet occur, in particular boiling evaporation of the liquid, so that the gases released in this first stage are so dry that they can be removed directly or possibly after cooling with a standard air pump or vacuum pump. In this case, in particular in this embodiment of the method, the pressure of the liquid to be degassed or degassed is reduced in the second depressurization stage after heating during high evaporation, preferably boiling evaporation, to such an extent that it achieves at least substantially and without uneconomic technical costs. the temperature it initially has before depressurizing in the first depressurization step. Thus, in this embodiment of the invention, a liquid is provided which has practically the same temperature as the fed liquid, but from which the gases contained therein have been virtually completely removed with very little energy consumption. The phrase "virtually completely" means 10 that the residual gas content of the liquid is no more than 5% of the starting gas content.

According to another embodiment of the method according to the invention, the steam-gas-15 mixture formed in the last depressurization step is fed to a condenser, preferably a surface condenser, which maintains the required vacuum by means of an air-exchange steam jet device.

20 The gases released during this condensing can be easily removed directly by means of an air pump or a vacuum pump.

The invention is explained in more detail below by means of one exemplary embodiment. Figure 1 schematically shows an apparatus used for carrying out the method according to the invention 25.

An apparatus for removing gases shown by way of example in Figure 1 The staple fiber spinning solutions consist of a multi-stage pressure reducer 3, two surface condensers 14, 18, 30, a steam jet device 17 and a vacuum pump 19.

The three-stage depressurizer 3 consists of a first depressurization chamber or a depressurization stage 4, ·, ·; a downstream heating chamber or heating step 35 5 and a downstream second depressurization step 6.

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A spinning solution containing gases at a temperature of 33 ° C is sprayed through the inlet nozzle 1 and the spray nozzle 2. The pressure of the first depressurization stage is set at 80 mbar. At this temperature and pressure, no significant evaporation of the aqueous spinning solution still occurs. In view of the increase in the boiling point of 3 ° C caused by the salts contained in the solution in this example, the spinning solution would only boil at a pressure of 42.2 mbar, and in the first depressurization step 10 the pressure is adjusted to 80 mbar.

On the other hand, a pressure of 80 mbar is enough to remove most of the air, hydrogen sulphide and carbon disulphide that accompany the spinning solution liquid. At this pressure of 80 mbar 15, 70-80% of the gases accompanying the spinning solution are released.

The spinning solution sprayed into the chamber of the first depressurization step 4 is collected in a collecting base 23 which separates the chamber of the first depressurization step 4 from the next chamber 5, namely the heating step of the depressurizer. The base 23 is made as a perforated plate through which the spinning solution liquid flows finely into the chamber of the heating step 5. Inexpensive heating medium 25 is then fed into the chamber of the heating step 5 via the inlet line 7, in the embodiment described here, exhaust steam from the evaporation plant, which is not substantially warmer than 34 ° C, most often 35-36 ° C.

«30 The pressure in the chamber of heating step 5 is maintained at 45 mbar, which corresponds to a spinning solution temperature of 34 ° C (note the increase in the boiling point of the spinning liquid of 3 ° C).

In the heating step 5, the pressure of the spinning solution 35 heated by at least 1 ° C is reduced, after the solution has passed from the bottom of the heating step 5 through the nozzle 11 to the chamber of the second depressurization step, to a pressure of 42.5 mbar. In this case, as a result of the "heat loss" caused by boiling, the initial spinning solution temperature of 33 ° C is again obtained, i.e. the temperature at which the spinning solution liquid is fed via the inlet nozzle 1 to the pressure reducer. Under these conditions, however, in the chamber of the second depressurization stage 6, strong evaporation of the body fluid, here water, takes place. In this case, the residual amounts of the gases still present in the spinning solution, in particular hydrogen sulfide and carbon disulphide, are released and removed with the steam. At the discharge nozzle 12 of the pressure reducer 3, the coil solution 10 removed from the second pressure reduction stage 6 contains at most 5% of the gases entering through the inlet nozzle 1.

The steam released in the second depressurization stage 6 through the outlet line 13 branching from the steam space of the second depressurization stage 6 and the residual amounts of hydrogen sulfide and carbon disulphide enter the outlet condenser 14 connected to the outlet line via a condenser 14.

20

Ventilation and maintenance of a pressure of 42.5 mbar in the chamber of the second depressurization stage 6 is provided by a ventilation steam jet device 17 connected after the ____ of the surface condenser 14. In this steam jet device 17, a 42.5 mbar steam-gas mixture drawn from the second depressurization stage 6 is compressed to, for example, 80 mbar. The steam-gas mixture thus compressed can then be fed at this pressure of 80 mbar by connecting a second surface condenser 18 to a vacuum air pump 19, from which the mixture leaves at atmospheric pressure. The gas mixture is then fed via line 20 to a hydrogen sulphide and carbon disulphide recovery plant.

In order to condense the maximum amounts of steam still carried by the exhaust gases, the cooling water required by the surface condenser 14 is preferably fed first via line 21 as shown in Fig. 1: to the surface condenser 18, from which it then flows through line 15 to the condenser 7 connected in front of the condenser. In this way, the required cooling water can be used optimally.

The gases 5 removed from the first depressurization stage 4 are also led via an exhaust gas line 22 to a surface condenser 18 connected to it, from where they, after cooling, are sucked out by means of an air pump 19 and conveyed at atmospheric pressure to a recovery line 20.

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Claims (6)

8 87735 A method for removing gases from gaseous liquids, wherein the pressure of the liquid is reduced in two steps and the liquid is heated between the two steps, characterized in that in the first step the pressure of the liquid is reduced so that no boiling evaporation occurs, but a large proportion of dissolved and insoluble the gases are separated from the liquid, 10 that in the second stage the liquid is heated to 1-2 ° C, and that in the third stage the pressure of the liquid is reduced to such an extent that the liquid reaches its initial temperature as a result of the boiling caused by the depressurization. 2. The first patent claim 1, which is incorporated herein by reference in its entirety. Method according to Claim 1, characterized in that the liquid is heated with exhaust steam. 3. A patent according to claims 1 or 2, which comprises a charge of 25 hours and a third of the three-way capacitors, the capacitors of the external capacitors are connected to the power supply. stor 30 i därefter anordnad andra yt- eller blandningskondensator, varefter ännu förekommande gaser mätäs direkt account en luft-pump. A method according to claim 1 or 2, characterized in that the steam-gas mixture released in the last depressurization step is fed to a surface or mixing condenser, the vacuum required in the condenser is maintained by means of a degassing steam jet device, and the steam is or in a mixing condenser, after which the remaining gases are fed directly to the air pump. 4. The invention is further adapted to a patent according to claims 1 to 35 3, which can be used as a spin-off for a staple fiber. 10 87735 Method according to one or more of Claims 1 to 3, characterized in that the gaseous liquid is a staple fiber spinning solution. 30 5. Test arrangements for the operation of a gas chamber and a gas chamber (3), for which the three-chamber chamber (4) and the upper chamber (5) have been used. tricks of the chamber (6), the chamber of the chamber (23, 11) of the chamber (17, 19) of the chamber (17, 19) of the chamber of the tram 7) 10 for the upstream energy accounts. A multi-stage pressure reducer for removing gases in liquids, characterized in that the pressure reducer (3) consists of three chambers in the following order, namely a first pressure reduction chamber 35 (4), a heating chamber (5) and a second pressure reduction chamber (6). means (23, 11) known per se for transferring liquid from one chamber to the next chamber, means (17, 19) for generating negative pressures in the pressure relief chambers and a joint (7) for introducing heating energy into the heating chamber. Pressure reducer according to Claim 5, characterized by 5 vacuum lines (22) which connect the gas space of the first pressure reduction stage (4) directly or interposed via a condenser (18) to a pressure relief pump (19). 10 1. Förfarande för avlägsnande av gaser frän vätskor in- nehällande gas, varvid vätsketrycket sänks i tvä steg och Vätskan mellan dessa tvä steg uppvärms, kännetecknat av att i det första steget Vätsketrycket sänks sä mycket, att kokn from 15 to 15 ° C, at least 1 ° C, at least 1 ° C, at least 2 ° C, at least three minutes, at the same time as the total of 1 to 2 ° C, ler sin ursprungliga temperatur. 20 6. A recording system according to claim 5, which comprises a transverse circuit (22), for which a three-sided pump (4) is provided directly or via 15 side-by-side pumps (18) to a three-sided pump (19).