DE3727164A1 - Process for the generation of low absolute pressures for the processing of oils and fats - Google Patents

Abstract

Process for the generation of low absolute pressures for the treatment of oils and fats, in which exhaust steam from the process, which contains oil and fat components, fatty acids and/or tallow as well as steam, is deposited by co-condensation using essentially circulated cooling fluid and cooled down before reuse in the co-condensation. The cooling fluid is cooled down by partial evaporation (flash evaporation). The cooling fluid itself is eventually generated by condensation of the exhaust steam from the process and essentially consists of water and of oils, fats, fatty acids and/or tallows which are emulsified and/or suspended in the water. The partial evaporation of the cooling fluid prevents the removal of heat being impeded by crystallised fat layers on the surfaces of the heat-transfer devices normally used. At the same time, the partial evaporation results in a condensate which is virtually completely free of oils and fats as waste water which does not pollute the environment. It is additionally possible to carry out the deposition of the oils, fats, fatty acids and/or tallows only after the cooling down. The condensation of the steam from the partial evaporation is carried out at temperatures above 0@C in continuous operation. If the process is applied at temperatures just above 0@C, there are advantages in the good effect of the deposition of the oils and fats and ... Original abstract incomplete. <IMAGE>

Description

The invention relates to a method in the preamble of claim 1 type for generating lower abso luter pressures for the treatment of oils and fats.

In known methods of the type in question the treatment of vegetable and animal oils and fats, e.g. in physical refining, in deodorization and by distilling the fatty acids by distillation, low absolute pressures between 0.1 and about 60 mbar turns. In this process, water vapor is injected to to reduce the partial pressure for the organic components and also the selective effect of water on steam pressure of the individual organic components. The process evaporation to be extracted at low absolute pressures holds oils, fats, fatty acids, sebum and / or water vapor similar components. To the organic components of this To get back steam as much as possible, it is common to send the process steam through vapor washers, the are loaded with an absorption liquid, the norma usually consists of related oils.

In the upper part of this pressure range between about 40 and 60 mbar known processes, it is common the raw or pre-cleaned process steam directly in mixing condensers that are cooled with cooling water and with a gas designed according to the condensation pressure suction pump are equipped.  

At the lower pressures between 0.1 and about 40 mbar it is known to use steam jet compressors to do this Vapor mixture to compress to a pressure at which the Steam mixture at a temperature above 0 ° C can be settled. Mixing capacitors are used be cooled with water. With mixed condensation, the Cooling water flow the condensate of the steam mixture and given if the motive steam of the steam jet compressors is on.

In order to reduce environmental pollution, it is known from the Cooling water flow and the condensate of the steam mixture the oil and remove fat as much as possible before this as Process wastewater is directed into the sewage system.

In a known further development of the method of the type concerned, the coolant flow after the fat separation and recooling in the circuit is returned to the mixed condensation for reuse and thereby to a flow of coolant enriched with oil and fats. The excess cooling water formed in the liquid phase from the condensate of the steam mixture - contaminated with oils, fats, fatty acids and / or tallow - is separated from the circuit. When the cooling liquid circuit is recooled, surface heat exchangers are used that allow the heat-absorbing cooling medium to be kept completely free of oils and fats. The pressure in the mixing condensate can be reduced by cooling the flow of coolant back through a chiller of any type to a temperature never lower. This measure can save energy. The invention relates to methods of this type, in which the coolant flow is circulated.

This known method has the disadvantage that in the heat exchangers used for recooling crystalline fixed or solidified layers of fat on the heat transfer form areas, which a cumbersome exchange operation of require at least two cooling devices. The each  loaded cooler must by heating and melting the fat layer to be regenerated. There is also the disadvantage that oils, fats, fatty acids and / or tallow only upstream can be deposited in front of the surface coolers, so not as effectively as possible downstream behind them Coolers at the lowest temperature, which is in the cycle occurs, otherwise the formation of layers of fat in the coolers is reinforced.

DE-OS 23 17 451 is a method and a front direction for the separation of fat material from vapors known, in which a part of the ent in the steam holding oils and fats can be separated. Before the mixing condensation becomes a coolant in such a small size Mass flow injected into process waste that through that partial evaporation a cooling of the process evaporation to the water vapor saturation point. This condenses part of the organic components of the process waste, and the condensate drops formed can be connected in a downstream Droplet separators are partially separated. This will the contamination of the downstream mixed condensation used cooling water reduced. A complete cleaning of the cooling water flow, however, cannot be reached in principle.

The invention has for its object the disadvantages to avoid the known method of the type concerned, thus the formation of crystallized or solidified fat to avoid layers on heat transfer surfaces and the Possibility to create a largely of oils at the same time and grease free condensate, which is good for the environment not burdened table.

The object underlying the invention is achieved by solved the teaching specified in the characterizing part of claim 1.

The invention is based on the basic idea, by users partial evaporation of the coolant instead the cooling down in surface heat exchangers heat dissipation through crystallized layers of fat avoid.  

In the partial evaporation, a vapor mixture is surprisingly obtained which consists almost entirely of water vapor and only consists of traces of oil and fat, which remain liquid even at low temperatures down to 0 ° C during the condensation. These oil and fat components therefore do not hinder condensation of the vapor mixture in a surface condenser. After the condensation, these small amounts of organic constituents can be separated from the water in a simple manner , if necessary at all. With this procedure, the cooling water should not be exposed to oil and fat components.

It is also possible that from partial evaporation Steam mixture obtained with traces of oil and fat to precipitate in a mixed condensation with cooling water. The low oil and fat contents are due to the mixture diluted with the cooling water so largely that this is not considered Environmental pollution.

There are special advantages if the partial ver vaporization of the coolant and also a separation of the oils and greases from the coolant circuit to one Temperature just above 0 ° C, preferably between 0 ° and 20 ° C be performed. On the one hand you get a steam that shows extremely low traces of oil and fat components, and on the other hand, the separation of oils and fats takes place from the coolant more effectively than with higher ones Temperatures.

Furthermore, it is in the application of partial ver steaming possible, the separation of oils, fats, fatty acids and / or tallow from the coolant circuit only current downward after its recooling. Here is the The highest possible effect of the separation is guaranteed because of this point of the cycle the lowest temperature and highest Concentration of the substances to be separated is present.

Based on the drawings, the invention is to Ausfü tion examples are explained in more detail.

Fig. 1 shows a first device for the implementing of the method according to the invention,

FIG. 2 shows a modification of the device according to FIG. 1,

Fig. 3 shows a modification of the apparatus of Fig. 2,

Fig. 4 shows another modification of Figs. 2 and

FIG. 5 shows a modified embodiment of FIG. 4.

In Fig. 1, a process engineering apparatus 1 for the treatment of oils and fats, which can be a damper for physical refining or for deodorization or also an apparatus for distillative fractionation for fatty acids, is acted upon by strip steam with a line 2 . After the absorption of undesirable oil and fat components, fatty acids and / or tallow, this process vapor stream is passed through a line 3 directly into a mixing condenser 4 . Cooling liquid is injected into the mixing condenser 4 through a line 5 and condenses the process vapor entering through the line 3 . The non-condensing gaseous components are discharged to a gas suction pump 7 through a line 6 .

The mixture of cooling liquid and condensate enters an evaporator 8 through a nozzle 9 . Here, the cooling liquid is cooled back by partial evaporation and then flows through a barometric downpipe 10 into an open downpipe box 11 . If too much cooling liquid should occur, this flows through the overflow pipe 12 . Missing coolant can be supplemented with water through a line 12 a . On the surface of the fall water box 11 , a layer 13 of oil and Fettbe constituents, fatty acids and / or tallows accumulates, which can be skimmed in any way, for example with hand tools. The cooling liquid is fed through a line 14 to a pump 15 , which conveys it back to the mixing condenser 4 .

The ge formed in the partial evaporation in the evaporator 8 corresponds in terms of mass essentially to the liquid excess caused by the inclusion of the condensate from the process evaporation stream in the mixing condenser 4 . This steam, which contains very little oil and fat, is discharged from the evaporator 8 through a line 16 into a surface condenser 17 , which is fed through a line 18 with a suitable coolant, such as air, water or cooling brine. The coolant flows through a line 19 after use. The clean condensate formed is withdrawn from the condenser 17 through a line 20 and discharged practically without environmental pollution. A line 21 leads the non-condensable portions from the condenser to a gas suction pump 22 .

To effect the partial evaporation of the cooling liquid flow, the pressure in the evaporator 8 and in the condensation space of the surface condenser 17 is kept lower than the pressure in the mixing condenser 4 .

Due to the constant absorption of the condensate from the process evaporation in the mixing condenser 4 , by the partial evaporation in the evaporator 8 and by the separation of oils and fats from the fallwater tank 11 , the cooling liquid changes its composition within the circuit and after a few hours only consists of parts that originate from the process of evaporating steam - even if the operation was first started with water.

Fig. 2 shows a modification of the device of FIG. 1, the same parts are provided with the same reference numerals. Process engineering apparatus 1 is supplied with strip steam for the treatment of oils and fats through line 2 . The process vapor formed here flows under low absolute pressure through a line 23 into a vapor scrubber 24 and partially cleaned further through a line 25 in a steam jet compressor 26th This is supplied with motive steam through a line 27 and compresses the process steam to the condensation pressure in the mixing condenser 4 . The mixture formed from the process vapor and the motive steam enters the mixing condenser 4 through the line 3 . This is supplied with coolant through line 5 . The non-condensable gases and vapors flow through line 6 to the gas suction pump 7 .

The sum of condensate and cooling liquid enters the evaporator 8 through the nozzle 9 . Here, the cooling liquid flow is partially evaporated due to the lower pressure compared to the pressure in the mixing condenser 4 . The rest flows through the barometric downspout 10 into the downwater box 11 . If there is too much liquid in the circuit, it flows out under an intermediate wall 28 through a weir 29 . Missing water can be replaced by line 12 a . A layer of oils and fats forms on the surface of the falling water box 11 , which is lifted out of the liquid by a conveyor belt 30 and conveyed over the container edge into a collecting box 31 . The main liquid stream partially cleaned in this way flows through line 14 to the pump 15 , which cools the liquid stream cooled by the partial evaporation to the required temperature back through line 5 to the mixer condenser 4 .

After the vapor formed in the evaporator 8 has been freed from liquid residues by a droplet separator 32 , this flows through the line 16 into a tube bundle upper surface condenser 33 , the heat flow downstream as a downflow evaporator for the through lines 34 , 35 , 36 and 37 for distribution to the United Pipe bundle injected refrigerant works. The refrigerant vapor is through a line 39 leads to a compression or absorption refrigerator, not shown, and comes from there in the circuit after condensation as condensate back through line 34 . The bundle condenser 33 formed in the tube condensate of the vapor from the evaporator 8 flows through a down pipe 40 into a down water box 41 from which it can be discharged through an overflow 42 practically clean without polluting the environment.

The tube bundle condenser 33 is advantageously operated so that the incoming steam through line 16 is just above 0 ° C, for example at 0.5. . . 8 ° C is precipitated. This allows a pressure of 6.3 in the evaporator 8 . . . 11 mbar are generated, which leads to a coolant temperature of 1. . . 9 ° C after the partial evaporation.

With little effort can be kept relatively large in the recooling by partial evaporation of the cooling liquid circuit stream, so that its warming up in the mixing condenser 4 and its cooling in the evaporator 8 to very small temperature differences of, for example, 1st . . Have 4 K reduced.

This makes it possible to reduce the pressure in the mixing condenser 4 to 1.5. . . Lower 4 mbar above the pressure in the evaporator 8 . Such a low pressure in the mixing condenser 4 of about 8. . . 15 mbar leads to low energy consumption in the upstream compressor, here the steam jet compressor 26 .

Fig. 3 shows a modification of the device of FIG. 2, corresponding parts are seen with the same reference numerals ver. In the process engineering apparatus 1 shown in FIG. 3, the stripped steam blown through line 2 is loaded with undesirable oil and fat components and flows as process evaporation through line 43 into the steam jet compressor 44 , which is acted on by line 45 with motive steam. This steam jet compressor is connected upstream of the steam jet compressor 26 , which further increases the pressure by means of the propellant steam entering through line 27 , except for the condensation pressure in line 3 in the mixing condenser 4 . This mixing condenser is equipped with cascade internals 46 , through which the cooling liquid supplied through line 5 flows down. The non-condensable, gaseous components are discharged through line 6 and an orifice 47 into line 16 .

The cooling liquid from the mixing condenser 4 passes through the nozzle 9 into the evaporator 8 . The vapor formed by partial evaporation is transferred through line 16 to a mixing condenser 48 which is fed with local cooling water through line 49 . After the condensation of the steam, this cooling water flows out through line 50 .

The uncondensed portions of the steam flow are passed through line 51 into a steam jet compressor 52 , which receives the required motive steam through line 53 . From the outlet of the steam jet compressor 42 , a line 54 leads into a mixing condenser 55 , which is supplied with cooling water from the line 56 branched off from line 49 . Cooling water and condensate flow out through line 57 . The uncondensed gases and vapors flow through line 58 to a water ring vacuum pump 59 used as a gas suction pump, which is connected to the atmosphere through line 60 .

The unevaporated portion of the cooling liquid is collected under the evaporator 8 in a closed separating tank 61 . A layer 62 of fat and oil is deposited on the surface of the water and is conveyed by a conveyor belt 63 , which is equipped with ribs 64 , over a container wall 65 into a collecting box 66 . A screw 67 is attached in the bottom area thereof and conveys the solidified and crystallized fats and oils to a displacement pump 68 . This expels the fats and oils through line 69 from the closed separation container 61 . The closed design of the separator prevents air from entering. In this way, a saturation of the coolant flow with air and a correspondingly high load on the steam jet compressor 52 and the water ring pump 59 is avoided.

The recooled main coolant flow flows through line 14 via pump 15 and line 5 back to the mixing condenser 4 . Through line 5 a part of the cooling liquid stream may be diverted if located too much thereof accumulates in the circuit, or water may be added if defect occurs.

Fig. 4 shows a modification of Fig. 1, corre sponding parts are provided with the same reference numerals. In Fig. 4, the process exhaust stream is fed through line 70 to a radial compressor or radial fan 71 which is driven by a motor 72 . Here, the pressure of the process vapor is increased so far that its condensation in the mixing condenser 4 can run above 0 ° C. The mixing condenser 4 is fed through the line 5 with cooling liquid. In the evaporator 8 , the mixture of cooling liquid and condensate flows through the nozzle 9 . The portion that does not evaporate flows through the downpipe 10 into the closed decanter 99 , which is completely filled with cooling liquid. Oils and fats accumulate in the upper hood 100 and are discharged continuously or in batches from time to time through the line 10 . A small part of the aqueous phase of the cooling liquid can also be removed from the circuit.

The recooled cooling liquid passes through line 14 to pump 15 , which supplies the mixing condenser 4 through line 5 . The non-condensable gas flowing out of the mixing condenser through line 6 is also discharged through an orifice 73 into a line 16 , which feeds the steam generated during partial evaporation in the evaporator 8 to a radial compressor 76 which is driven by a motor 77 . The compressed steam continues to flow through line 78 into surface condenser 17 , to which cooling water is supplied through line 18 and which flows off again through line 19 . The condensate of this steam flows through the hot well 79 and further through the line 80 with virtually no pollution of the environment.

From the hot well 79 , the non-condensed gases and vapors are passed through line 21 to the gas suction pump 22 of any design. Line 81 connects to the atmosphere.

Fig. 5 shows a further modified embodiment, and corresponding parts are provided with the same reference numerals. In Fig. 5, process evaporation is fed through line 82 to a rotary displacement compressor 83 , which may belong to the class of screw or roots compressors. The compressed to the condensation process vapor reaches ge through line 3 in the mixing condenser 4 , which he receives the required cooling liquid from line 5 . The non-condensing gas and vapor components flow through line 6 and through orifice plate 73 into line 90 .

In this case, the mixing condenser 4 and the evaporator 87 are separated, and the fallwater box 11 , in which the oils and fats are separated, is arranged between these two apparatuses.

From the mixing condenser 4 , the cooling liquid and the condensate flow through a down pipe 84 in the open case water box 11 , the liquid content of which is kept constant by the overflow pipe 12 and the feed line 12 a . The settling layer 13 of fat and oil can be skimmed off in any way. The coolant flow flows through line 14 to a pump 85 which conveys it through line 86 into an evaporator 87 . After the partial evaporation taking place there, the cooling liquid flows through line 88 to pump 89 and is injected again through line 5 into the mixing condenser 4 .

The vapor formed in the evaporator 87 by partial evaporation from the cooling liquid stream flows through line 90 into a steam jet compressor 91 , which is supplied with motive steam through line 92 . The vapor compressed there is then passed through line 93 into a mixing condenser 94 , to which cooling water through line 95 is applied. Cooling water and condensate flow practically clean through a downpipe 96 . Through line 97 , the non-condensed gas and steam components are fed to a gas suction pump 98 , which is connected to the atmosphere.

.. And thus the deposition of fats and oils and the generation of the vapor by partial evaporation of the cooling liquid - - with the method embodiments according to Figures 4 and 5 of the circulation of the cooling fluid flow can be carried out just above 0 ° C, although no compression and Absorption chiller is applied. In this temperature range, on the one hand, a high effect in the oil and fat separation from the coolant in the container 99 ( FIG. 4) and in the fall water tank 11 ( FIG. 5) can be achieved and, on the other hand, by the partial evaporation of the coolant in the evaporator 8 ( Fig. 4) and in the evaporator 87 ( Fig. 5) achieve a particularly low content of oil and fat components in the steam.

Claims (15)

1. A process for generating low absolute pressures for the treatment of oils and fats, in which oil and fat shares, fatty acids and / or tallow and water vapor ent process evaporation essentially completely by mixed condensation with essentially circulated, mainly from water and from cooling and emulsifying oils, fats, fatty acids and / or tallows emulsified and suspended therein, which is essentially obtained by condensation of the process vapor, which can be at least partially freed from oil and fat components before being reused in the mixed condensation and by Heat extraction is cooled back, characterized in that the cooling liquid is cooled back by partial evaporation and the steam formed is condensed in preferably continuous operation at temperatures above 0 ° C. 2. The method according to claim 1, characterized shows that the low absolute pressures in the Range from 0.1 to about 60 mbar. 3. The method according to claim 1, characterized records that the partial evaporation of the cooling liquid and the condensation of the resultant Steam at temperatures just above 0 ° C, preferably between 0 and 20 ° C.   4. The method according to claim 1, characterized in that the steam generated by partial evaporation of the cooling liquid is precipitated in a subsequent mixing condenser ( 48 ), which is acted upon by cooling water. 5. The method according to claim 4, characterized in that the cooling water from the Mischkonden sator (48) cooled down by heat extraction, for example in a cooling tower and is recirculated essentially in a circuit for mixing condenser (48). 6. The method according to claim 1, characterized records that the by partial evaporation of the Coolant generated steam in a surface condenser sator is deposited, which is cooled by cooling water becomes. 7. The method according to claims 1 and 3, characterized characterized in that by partial ver Evaporation of the cooling liquid produces steam at temperatures just above 0 ° C in a surface condenser hit by low temperature cooling brine is cooled. 8. The method according to claims 1 and 3, characterized characterized in that by partial ver Evaporation of the cooling liquid produces steam at temperatures just below 0 ° C in a surface condenser is struck, the heat flow downstream as a refrigerant evaporator of a compression refrigerator works. 9. The method according to claims 1 and 3, characterized characterized in that by partial ver Evaporation of the cooling liquid produces steam at temperatures is condensed in a condenser just above 0 ° C, the heat flow downstream as a refrigerant evaporator of a ge  closed absorption chiller works. 10. The method according to claim 1, characterized records that the by partial evaporation of the Vapor generated by liquid coolant through single or multi-stage Steam jet compressors compressed and in a mixing or Surface capacitor is condensed. 11. The method according to claim 1, characterized records that the process exhaust stream upstream from the mixed condensation in the coolant by or multi-stage compressors from the pressure during treatment the oils and fats down to the mixed condensation pressure is compressed. 12. The method according to claim 11, characterized records that as single or multi-stage compressors Steam jet compressors are used, their motive steam mixes with the process evaporation and with this ge together through the mixed condensation in the coolant is put down. 13. The method according to claim 10, characterized records that as single or multi-stage compressors Radial compressors or rotary lobe compressors are used will. 14. The method according to claim 1, characterized records that the separation of oils, fats, fats acids and / or tallow from the coolant flow down after that caused by partial evaporation Recooling of the coolant flow takes place. 15. The method according to claim 1, characterized in that the mixed condensation with the cooling liquid is carried out in a mixing condenser ( 4 ) which is arranged above an evaporator ( 8 ), preferably forms a common container with this.