DD141413A1 - METHOD FOR DRYING HYDROGEN-CONTAINING GASES IN PETROLEUM PROCESSING EQUIPMENT - Google Patents

Abstract

The invention relates to a method for drying Hydrogen-containing gases during start-up or in the Activation of catalysts in oil processing plants, especially in catalytic reforming, using of molecular sieves with the aim of the regeneration temperatures for the Molecular sieves while maintaining the adsorption capacity lower. With the method according to the invention, the regeneration. gradually at different temperatures and pressures a possibility is shown, with a simple one Solution and low technical effort drying the to carry out hydrogen-containing gases.

Description

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Process for drying water-containing gases in petrochemical plants · _r. -. . '; _i

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Field of application of the invention \ mg

The invention relates to a method for drying hydrogen-containing gases during start-up or in the activation of the catalysts in petroleum processing plants, for. As in the catalytic reforming, using molecular sieves.

Characteristic of the known technical solutions

It is known that the requirements for the water vapor content in hydrogen-containing gases used in catalytic processes of petroleum processing, such. B. reforming processes are present, were constantly increased. Thus, US Pat. No. 3,705,094 claims less than 10 ppm of water in the circulating gas, and DD-WP 122101 assumes that the process takes place in an environment which is substantially anhydrous. Of particular importance is the water vapor content during startup processes, be it the first use of catalysts or during and after the reactivation of the catalysts, which are required after different maturities. In order to avoid damage to the catalysts, it is possible to adjust the temperature required for the desired product quality only after lowering the water vapor content in the hydrogen-containing gas.

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There are various methods for lowering the water vapor content in the process gases during the starting processes. One possibility is that a portion of the hydrogen-containing gases is constantly discharged from the circuit. However, this procedure has the disadvantage that the amount of gas that can be discharged is limited, so that the water vapor content can be reduced to the required values of sometimes less than 50 ppm of water only after a long time, and can be adjusted only to a limited extent.

Other processes remove the water vapor from the process gases of petroleum processing by adsorption, for example on alumina, silica gel or molecular sieves. The use of aluminum oxide or silica gel has the disadvantage that the capacity of these adsorbents is low and so low water vapor contents, as required during startup or during and after the reactivation of the catalysts in reforming plants, can only be achieved with great technical effort.

Also known are processes which use molecular sieves for the drying of gases. Such a process is described in DD-WP 70 555. However, some applications of the process are counteracted by the high temperature of more than 250 C required for the regeneration of the molecular sieves and which can only be achieved with v / -end means for heating the regeneration gases, which in turn are difficult to fit into existing equipment, if only low water vapor contents can be permitted in the process gases to be dried, as is the case when starting up petroleum processing plants · These problems occur especially when new catalysts are to increase the efficiency of existing plants and the existing technical system supplements them necessary equipment is not possible or only with great effort

Object of the invention

The aim of the invention is an economical process for the drying of hydrogen-containing gases during the first start-up or during and after the catalyst reactivation in the catalytic! Petroleum processing, z. As in the catalytic reforming, which eliminates the disadvantages of known drying methods using molecular sieves, in whole or in part.

Presentation of the nature of the invention

The invention is based on the object at start-up or in the activation of the catalysts in petroleum processing plants, for. As reforming plants to dry the hydrogen-containing gases using molecular sieves and to avoid the disadvantages of known methods, which consist in that high molecular sieve capacities, which allow ei'zusteilen the low water content e in the hydrogen-containing gases, only with high Regeneration temperatures are reached. The high regeneration temperatures can be achieved in many applications only with unacceptably high technical complexity. Surprisingly, it has been found that the drying of hydrogen-containing gases with molecular sieves at 1 to 3 MPa and 10 to 60 C can be carried out when the molecular sieves are regenerated in stages at temperatures below 200 ⁰ C. This gives them an adsorption capacity which is sufficient to set the required low water vapor contents for start-up operations in petroleum processing plants.

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Conveniently, the regeneration of the molecular sieves is carried out so that in a first stage, the hydrous molecular sieve with a substantially dry gas stream consisting of air, nitrogen or other non-absorbable gases or mixtures of these gases with one another, at 0.1 to 1.0 MPa and 70 ⁰ C is as long-heated until the Wasserdampfpartiäldruck Adsorberausgang at approximately the V / asserdampfpartialdruck on Adsorbereingang equal ·

In a zweiten.Stufe, is to further reduce the water content of the molecular sieves, a substantially dry gas stream consisting of air, nitrogen or other gases or mixtures thereof nichtsorbierbaren heated to less than 200 ⁰ C at 0.1 to 1.0 MPa and passed through the molecular sieves until the water vapor partial pressure at the adsorber outlet approximately matches the water vapor partial pressure at the adsorber inlet.

The third and final stage of regeneration of the molecular sieves is carried out in such a way that while maintaining a low gas flow of air, nitrogen or other nichtsorbierbaren gases or mixtures thereof with less than 200 ⁰ C, a vacuum of 5 to 50 kPa is applied to the dryer system and thereby a further reduction of the water content is achieved on the molecular sieves.

In setting the individual regeneration stages, the process is so flexible that the following stage can already start, before a complete equalization of the partial vapor partial pressures has been established in the preceding one.

Ausführungsbe! Game

On the hand of * Pig. 1 describes the technological process of gas drying.

Into the adsorber 1, which is filled with type 5A molecular sieve, is passed through line 8 a non-absorbable regeneration gas, eg air, which is essentially anhydrous, in which the valves 7 and 17 are opened. The flow of regeneration gas previously passed through a heat exchanger 2 and heated at 0.1 MPa at 70 ⁰ C · the water vapor partial pressure is in the regeneration gas to the valve 17 determined by conventional methods ·

After reaching approximately the same values in the lines 8 and 18, the temperature of the regeneration gas at 0.1 MPa to 170 ⁰ C is set and the gas stream until reaching approximately matching values for the Y / asserdampfpartialdruck in the lines 8 and 18 maintained "Thereafter by closing the armature 17 and opening the armature 15 to the adsorber 1 made a connection to the line 16 to the vacuum generator 16 and a negative pressure of 0.02 MPa applied, being set by the armature 7, a small flow of the regeneration gas air to a to achieve further lowering of the water content of the molecular sieve

For inerting the dryer system, the valves 7 and 15 are closed and passed through line 6 nitrogen at 0.6 MPa and 25 ⁰ C via the valve 5 in the adsorber simultaneously with the setting of less than 0.5 vol .-% oxygen the cooling of the molecular sieve is carried out below 40 ^° C.

The flushing out of the purge gases takes place via the fittings. 9 and 11 and the line 12 · Thereafter, the valves 5 and 11 are closed and kept the adsorber 1 ready for the drying phase.

In the drying of hydrogen-containing gases during the startup of the reforming system, the valves 3 and 9 are opened and the valve 19 is closed * This is through the line 4, the hydrogen-containing gas, eg. B · circulating gas, conducted at 2.0 MPa and 40 ⁰ C through the adsorber 1, and first discharged as a purge gas via line 12 ·

If the hydrogen-containing gas in the line 10 has a water content of less than 50 ppm, the fitting 13 is opened and the fitting 11 is closed, whereby the dried hydrogen-containing gas is fed through the line 14 into the reforming plant for the hydrogen-containing gas has a water content of less than 50 ppm, the dryer 1 is removed by opening the valve 19 and closing the valves 3 and 13 from the circulation and the hydrogen-containing gas from the line 4 is given directly via line 20 to the reforming plant, After this drying phase, the inerting of the adsorber 1 and the renewed regeneration follow.

It is a feature of the process of the invention that the regeneration of the molecular sieves is carried out in three stages. This gives the advantage that the regeneration temperature can be below 200 ⁰ C to set the required high adsorption capacity of the molecular sieves · Thus, the inventive method can be advantageous for adjusting the low moisture contents in the hydrogen-containing gases, as used in petroleum processing

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For example, in order to be able to set the desired high reformate qualities in reforming plants within a very short time, it is achieved that the process according to the invention makes it possible to use molecular sieve drying for those cases in which it is not or only With high technical complexity is possible, high temperatures for molecular sieve regeneration. apply "

Claims (1)

He thinks of late Process for the drying of hydrogen-containing gases during start-ups or in the activation of the catalysts in petroleum processing plants, preferably catalytic reforming using molecular sieves, characterized in that the regeneration of the molecular sieves using the media present in the plants in a multi-stage process in which the Molecular sieve at pressures of 0.1 to 1.0 MPa, preferably 0.1 to 0.3 MPa, is heated to temperatures of 70 ⁰ C until the partial pressure of water vapor at the Adsorberausgang approximately "corresponds to the water vapor partial pressure at the Adorber input, then at the same pressures Temperatures below 200 ⁰ C is heated, this temperature is maintained until the water vapor partial pressure of the regeneration media at the adsorber inlet and Adsorberausgang is approximately equal and the further reduction of the water content of the molecular sieves by desorption in a vacuum of 5 to 50 KPa, preferably from 10 to 30 KPa. For this / I page drawing