DE2111942A1 - Regenerating gas adsorber - Google Patents

Abstract

In adsorption drying of gas for further prepn. in low-temp. plants, a portion of the flow leaving the adsorber is branched to regenerate the adsorber which has received moisture, a second portion being branched to cool the regenerated adsorber. The gas stream humidified by this regeneration is dried in an auxiliary adsorber to the dew-point of the main gas flow leaving the main adsorber, then rejoins this flow.

Description

Process for adsorptive drying of gases for further processing the same gases in cryogenic systems The invention relates to a method for adsorptive drying of gases for further processing of the same gases in low temperature systems, in which a partial flow of the gas flow after the adsorption is used to regenerate the in the adsorption period illite moisture-laden dCjorber and a partial flow to be diverted to the cooling of the regenerated adsorber.

hs a method for adsorptive drying of gas is known at from which a partial flow is branched off from the main gas flow after drying. This Partial flow is passed through a regenerated adsorber to bring it to operating temperature to cool, then heated and placed in a moisture-laden adsorber, which served to absorb water in the previous adsorption period, whereby the adsorber is regenerated and the partial gas flow dis absorbs moisture. The partial gas flow is then cooled and passed into a suasserabscheider, whereupon it is fed back to the main gas flow.

A method for adsorptive drying of gas is known which branched off a partial flow from the main gas flow before drying, through a regenerated adsorber out to cool it to operating temperature, then heated and placed in a moisture laden @dsorber used in the previous Adsorption period used to absorb water, is passed, with the adsorber is regenerated and the partial gas flow absorbs the moisture. After that, the Gas partial flow cooled and passed into a water separator, whereupon he again the Main gas flow is fed before drying.

in another known process for adsorptive drying &. of gas, a partial flow is branched off from the main gas flow before drying, heated and placed in a moisture-laden adsorber in the previous one Adsorotion period was used for water uptake, conducted, with the moisture desorbed from the absorber and absorbed. Then the partial gas flow is cooled, passed into a water separator and then back to the main gas flow before drying; fed. After drying, the main gas flow becomes a further partial flow branched off into another adsorber that was previously in the desorption period heated, is passed to cool it. Then the partial gas flow self-cooled and, like that, fed into the main gas flow after it has been dried.

Also known is a method for adsorptive drying of Gas in which a partial flow is diverted from the main gas flow after drying and into another adsorber that was previously heated in the desorption period, is conducted to cool it. The regeneration takes place by supplying heat another gas flow that flows through cooler, water separator, fan, heater and the adsorber to be regenerated is conducted in a closed circuit.

The main part of all the procedures mentioned is a relatively high dew point of the main gas flow, since the partial gas flow used for the generation, the pressure and temperature with water vapor according to the water separation is saturated, fed back to the main gas flow or

through the use of the moist partial gas flow for rendering only an incomplete desorption of the .asaer is achieved will. Around To remove the residual moisture from the adsorber, higher absorption temperatures are required and thus a @@@@@ srar ensrgie effort required.

@er @invention is based on the call, a process for el @ erptive Developing drying of gases, with an extremely low dew of the dried Gases to ensure a long operating time of the downstream low-end @@@ door system is achieved. The process should be so old that the cold the residual gas fraction of the downstream cryogenic system in an economical way can be used.

According to this, the task is solved in that the währea @@ of the regeneration humidified partial gas flow in an additional adsorber except for the of the adsorption present T @ uppunkt of the gas @ a main stream dried and then again is added to the dry gas main stream.

The drying process is expediently carried out during the re-generation humidified gas partial flow uses two additional adsorbers, their ßbetrieb alternately he follows. the two additional adsorbers can with a cold residual gas fraction the downstream cryogenic system, preferably with a nitrogen fraction, regenerated and cooled. An expedient embodiment of the procedure provides before that the to regenerate the loaded adsorber and to cool the regenerated Adsorbers used partial gas flows in mutual heat exchange on a medium one The temperature is increased and then cooled to the temperature of the main gas flow be, upstream; s ;; ice with the cold residual gas fraction of the downstream cryogenic system.

Advantageously, the individual flow rates are determined with the help of Pressure regulators set.

The advantage of the method according to the invention is that very large amounts of gas, for example 100,000 Nm3 / h, in a very economical manner for the further processing of the dried gas in a cryogenic separation plant required, extremely low dew point -70 ° C to -80 ° C. It is particularly noteworthy that the adsorbers used to desorb and cool down Gas partial flows can be fed back into the main flow with almost no loss and that the otherwise usual gas losses when releasing the loaded adsorber avoided as the operating pressure during desorption corresponds to that of oil absorption.

The process is particularly profitable because the cold of the waste nitrogen @ reaction from the downstream low-temperature separation system for heat exchange in an economical way is used in the drying plant. The developed procedure in connection with the specified switching intervals also enables continuous Operation of the furnace for heating the regeneration gas, which due to its large Dimensions are only shut down for certain periods of time under difficult circumstances then started again;,! can ground, The method is particularly suitable for the drying of natural gas.

The invention will be closer to an embodiment below In the accompanying drawing, Fig. 1 shows a diagram of the process Fig. 2 the sequence of the work steps Fig. 3 the tamper @ turv @ r flow of the @ work steps.

The natural gas is through the raw gas inlet line 1 in the first and second adsorber 2 and 3 passed, in which it is by adsorption with conventional adsorbents, preferably synthetic zeolites, dried. In the most considered example the natural gas is dried simultaneously in two adsorbers operated in parallel. In principle, however, it is possible to use only one adsorber for this drying, The natural gas streams dried in the first and second adsorbers 2 and 3 decompose in the Raw gas outlet line 4 combined. At the first junction 5, part of the dried natural gas via the regeneration gas line 8 and removed from the second Branch 7 is again divided into two partial flows. Part of the gas is through the cold gas line 8 and the first pressure regulator 9, the latter determining the quantity ratio of the dry natural gas partial flows to warm up or cool down the adsorbers, to the cooler 10, in which it is brought to a temperature by heat exchange with a cooling medium is cooled from 5 to 10 ° C.

According to the invention, the cold medium is used as the cooling medium; Nitrogen fraction produced by the cryogenic system is used.

The cooled dry raw gas is through the cold gas line 8 in the third adsorber 11 passed, which in the previous desorption period with hot gas was charged. When flowing through the third adsorber 11, the cold raw gas heated and the adsorber cooled down, e.g. from 25,000 to 3,000.

The now heated raw gas leaves the third adsorber 11 via i £ -ltgasaustritbsleitung 12, passes the heat exchanger 13 and is then passed into the first cooler 14 and cooled down here to a temperature of approx. 3000. Again serves as a cooling medium the cold waste nitrogen fraction. The cooled gas is then transferred to the first Integration 15 in the Main flow of dried natural gas in the raw gas outlet line 4 fed in. With the second pressure regulator arranged in the raw gas outlet line 4 13 the pressure difference required for the feed is set.

The other part of the dried raw gas comes from the second branch 7 stirred into the furnace 18 via the hot gas line 17 and heated to the regeneration temperature, for example 25000, heated and opposite to the previous loading direction passed through the fourth adsorber 19 to be heated. With the resulting When the adsorbent bed is heated, the adsorptively bound water is desorbed and with the gas from the adsorber / discharged. The now moist gas is discharged through the hot gas outlet line 20 passed into the heat exchanger 13, in which the gas flows by heat exchange 20 and 12 is achieved that both streams the heat exchanger with a middle constant temperature, for example 140 ° C, leave. The one from the fourth adsorber 19 passed through the heat exchanger 13 regeneration gas partial flow is then in the second cooler 21 performed, also by exchange with the cold nitrogen fraction cooled and condensed in the water separator 22 by the temperature increase water freed.

To the extremely low dew point in the first and second adsorber 2 and 3 to be able to maintain a dried raw gas stream from -70 ° C to -80 ° C, the gas flow leaving the separator 22 is passed into the additional adsorber 23 and here again by means of conventional adsorbents, preferably synthetic zeolites dried. This dried gas stream is in the main stream of the dried Natural gas fed to the second connection 24.

To ensure continuous drying of the separator 22 leaving Regeneration gas stream to enable, the additional @ dsorber 25 is available, which alternates with the additional adsorber 23 is operated, i.e. while the additional adsorber 23 is being loaded, for example, the additional adsorber 25 is regenerated. @Waste nitrogen is used for regeneration the @ ieftemperaturtren @ system through the nitrogen line 25 by means of a fan 27 a heater 28 to; e leads, in which the nitrogen to regeneration temperature, for example 250 ° C, is heated. The warm gas is used for desorption in the additional adsorber 25 out, and then blown through the nitrogen outlet line 29 into the open. Afterward is used to cool the heated additional wheel -:.: o, over 25 through the nitrogen line 26 incoming nitrogen fraction bypassing the fan 27 directly into this @isorber given, after which it is also blown through the nitrogen outlet line 29 into the open will.

In the example considered above (FIG. 1) there are four adsorbers 2; 3; 11; 19 are available for drying the wrd gas.

wiese four adsorbers are operated alternately, so that each of the Adsorber by switching the work stages adsorbing (drying), desorbing by supplying heat with hot gases and cooling down to operating temperature, whereby Load two adsorbers each and the other two cooled or heated .. earth.

For the purpose of continuous operation of the heating for the regeneration gas The furnace 18 used are the working stages of all adsorbers with respect to one another in terms of time offset by T / 2, where T is the loading time of an adsorber. The duration of heating and The cooling period is T / 2 in each case. This ensures continuous operation of the furnace 18 possible.

The relationship between the work stages of the individual adsorbers 9 3; 11; 19 is in Fi. 2 shown. The digits 2; 3; 11; 19 in Fig. 2 correspond to the in Fig. 1 shown adsorbers.

The horizontally hatched sections represent the heating period and the vertically hatched sections represent the cooling period.

The non-dashed sections represent the adsorption period. In Fi. 3 is the temperature profile from the idsorbers 2; 3; 11; 19 exiting Regeneration gas flows (warm and cooling gas) shown schematically. On the abscissa is the time in sections of T / 2, for example 4 hours, plotted and on the ordinate is the temperature of the regeneration gas streams when leaving the adsorber in 00. The cooling period is shown as a dashed line and the heating period is shown in solid lines.

Using the Fi ». 2 and 3, the sequence of the work stages in the above Example are explained in the following korm.

If the natural gas coming through the raw gas inlet line 1 is in the The first and second adsorbers 2 and 3 are dried, the third adsorber 11 becomes cooled and the fourth adsorber 19 charged with hot gas. At time T / 2 is the loading of the first adsorber 2 ended. The previously to be dried in the adsorber 2 Raw gas partial flow is now passed through the third adsorber 11, while the first Adsorber 2 is charged with hot gas and the fourth adsorber 19 is cooled. The second adsorber 3 continues to be loaded. At the point in time T, the loading is carried out in an analogous manner of the second adsorber 3 ended, and the fourth adsorber 19 now with the one to be dried Raw gas partial flow is charged, the first adsorber 2 is cooled and the second adsorber 3 charged with hot gas. The third ad before 11 is loaded further. This switchover the Ädsorbor is continued analogously over the entire operating period: it continues, with each individual adsorber according to the loading time T in the time. T / 2 heated and in time / 2 back to iidsorption temperature, for example 30 ° C, cooled will.

As a special variant of the process in conjunction with a It is possible to use the heat exchanger 13 and the two To combine coolers 14 and 21 in an appropriately sized heat exchanger.

This then results in hot gas, cooling gas and the waste nitrogen fraction the downstream low-temperature decomposition system in heat exchange with each other.

What is more, in certain applications it is beneficial to use Carry out desorption of the adsorber in the same flow direction as the loading, while the cooling takes place against the previous direction of flow.

Claims (5)

Claims iq Process for adsorptive drying of gases for further processing the same gases in cryogenic systems, each from the gas stream after adsorption a partial flow for regenerating the moisture loaded in the adsorption period Adsorber and a partial flow for cooling the regenerated adsorber are branched off, characterized in that the partial gas flow humidified during regeneration in an additional adsorber except for the dew point of the after adsorption Main gas flow is dried and then added again to the main dry gas flow will. 2. The method according to claim 1, characterized in that for drying two additional adsorbers are used for the partial gas flow humidified during regeneration are operated alternately. 3. The method according to claim 2, characterized in that the two Additional adsorber with a cold residual gas fraction from the downstream low-temperature system, preferably with a nitrogen fraction, regenerated and cooled. 4. The method according to any one of claims 1 to 3, characterized in that that the to regenerate the loaded adsorber and to cool the regenerated Adsorbers used partial gas flows in mutual heat exchange on a medium Brought to temperature and then cooled down from the temperature of the main gas flow, Preferably with the cold residual gas fraction of the downstream low-temperature system. 5. The method according to any one of claims 1 to 3, characterized in, that the individual flow rates are set with the aid of pressure regulators.