METHOD FOR PRODUCING AN ADSORPTION AGENT FOR TREATING COMPRESSED GAS AND AN ADSORPTION DEVICE PROVIDED WITH SUCH AN ADSORPTION AGENT

Abstract

A method for manufacturing an adsorption agent for treating compressed gas, which includes the steps of providing a monolithic supporting structure; producing a coating suspension that includes an adsorbent; applying the coating suspension on the supporting structure to form a coating; applying a thermal treatment to the coated supporting structure in order to sinter the coating.

Claims

1-25. (canceled)

26. A gas compressor system comprising: an air compressor; and an adsorption device provided with an adsorption agent obtained with a method comprising the following steps: providing a monolithic supporting structure, wherein the monolithic supporting structure contains between 200 and 1200 cells per square inch (CPSI); choosing an adsorbent based on a treatment for drying the compressed gas from a compressed gas system, wherein the adsorbent is at least a drying agent that adsorbs moisture in the compressed gas from the compressed gas system; producing a coating suspension that comprises the adsorbent, wherein for the production of the coating suspension the adsorbent is selected which comprises a hydrophilic zeolite; applying the coating suspension on the supporting structure to form a coating; applying a thermal treatment to the supporting structure with the coating, in order to sinter the coating; wherein the applying the coating suspension on the supporting structure comprises the step of flushing or perfusing the supporting structure with the coating suspension; wherein the perfusion of the supporting structure is done from bottom to top in the opposite direction to gravity; wherein the perfusion is realized by a pump that pumps the coating suspension upwards through the supporting structure; wherein coating material is removed after the perfusion of the supporting structure with coating suspension; and wherein the removal of surplus coating material is realized by reversing the operation direction of the pump.

27. A method for manufacturing an adsorption agent comprising the following steps: choosing an adsorbent based on a treatment for drying compressed gas, wherein the adsorbent is at least a drying agent that adsorbs moisture in the compressed gas from a compressed gas system; producing a coating suspension that comprises the adsorbent, wherein the adsorbent comprises a hydrophilic zeolite; applying the coating suspension to a supporting structure to form a coating; and sintering the coating by a thermal treatment; wherein said applying comprises perfusing the supporting structure with the coating suspension, said perfusing is done in the opposite direction to gravity, and said perfusing is realized by a pump that pumps the coating suspension upwards through the supporting structure; and further comprising removing a portion of the coating material after the perfusing, wherein the removing is realized by reversing the operation direction of the pump.

28. A method for drying a compressed gas from an air compressor comprising the steps of: manufacturing an adsorption agent according to claim 27; providing the adsorption agent in a drying device comprising at least two vessels; drying the compressed gas from a compressed air compressor by guiding the compressed gas through the drying device, wherein a drying efficiency of the drying device is increased at least three folds using the adsorption agent.

29. The method according to claim 27, wherein for the production of the coating suspension one or more of the following materials are selected for an adsorbent: a zeolite, silica gel, activated alumina, activated carbon, metal-organic frameworks, carbon molecular sieve (CMS), an impregnated adsorbent and a hybrid adsorbent.

30. The method according to claim 27, wherein the adsorbent comprises faujasite zeolite type X.

31. The method according to claim 27, wherein the step of producing the coating suspension comprises the following sub-steps: providing a solvent; adding the adsorbent to the solvent to form a mixture; and adding a binder material to the mixture.

32. The method according to claim 31, wherein after the addition of the adsorbent to the solvent and the mixing of the adsorbent with the solvent, the adsorbent particles are reduced in size by wet milling.

33. The method according to claim 32, wherein the particle size of the adsorbent is reduced in size until D.sub.50 is less than 10 μm.

34. The method according to claim 31, wherein one or more of the following inorganic binder materials are selected as a binder material: colloidal silica; alumina; and/or clay.

35. The method according to claim 31, wherein one or more of the following organic binder materials are selected as a binder material: methyl cellulose; polymers such as acrylic resins, vinyl resins and similar; and/or a material of the cellulose group.

36. The method according to claim 27, wherein said removing comprises applying one or more pressure pulses of a purge gas through a channel of the supporting structure.

37. The method according to claim 27, wherein the thermal treatment comprises three phases: increasing the temperature during the first time interval t.sub.1-t.sub.0; keeping the temperature constantly high at a value above 400° C. during a second time interval t.sub.2-t.sub.1; decreasing the temperature back to ambient temperature during a third time interval t.sub.3-t.sub.2.

38. The method according to claim 37, wherein the temperature is kept constant during the second time interval t.sub.2-t.sub.1.

39. The method according to claim 27, wherein the step of producing the coating suspension comprises the addition of one or more additives.

40. The method according to claim 39, wherein the one or more additives contain one or more of the following agents: an additive to affect the acidity (pH value); and an additive to counteract foam formation.

41. The method according to claim 40, wherein the additive to affect the acidity consists of hydrogen chloride or ammonia.

Description

[0026] With the intention of better showing the characteristics of the present invention, a few preferred variants of a method according to the invention for manufacturing an adsorption agent for treating compressed gas are described hereinafter by way of an example, without any limiting nature, with reference to the accompanying drawings, wherein:

[0027] FIG. 1 schematically shows a possible embodiment of a method according to the invention for manufacturing an adsorption means;

[0028] FIG. 2 shows a possible temperature variation that could be applied in a method according to the invention.

[0029] FIG. 1 shows a block diagram whereby each block presents a step of the method according to the invention and whereby in some blocks a number of sub-steps are distinguished between.

[0030] Essentially the method according to the invention for the manufacture of an adsorption agent for treating compressed gas consists of a step 1A of providing a monolithic supporting structure and a step 1B consisting of the production of a coating suspension that contains an adsorbent.

[0031] In the next step 2 the aforementioned coating suspension is applied to the aforementioned supporting structure to form a coating and, finally, in step 3 a thermal treatment is applied to the resulting supporting structure with the coating obtained after step 2, in order to sinter the aforementioned coating in order to finally obtain an improved adsorption agent.

[0032] According to a preferred, but not necessary, characteristic of the invention a ceramic structure that contains cordierite, for example Celcor© by Corning, is selected for the monolithic supporting structure.

[0033] Alternatively, according to the invention, other materials can also be used for the manufacture of the supporting structure concerned, such as: [0034] other ceramic materials such as mullite, γ- or α-alumina or silicon carbide (SiC); [0035] metal foil; [0036] a fibre structure, for example based on glass fibre, ceramic fibre or other fibres, or a mixture of different types of fibres; or [0037] a polymer.

[0038] It goes without saying that the aforementioned list is not exhaustive and the use of other materials is not excluded.

[0039] According to the invention, it is not excluded either that the monolithic supporting structure is made of a combination of two or more of the aforementioned and/or other materials.

[0040] According to a preferred characteristic of the invention the material from which the supporting structure is made preferably contains between 200 and 1200 CPSI (cells per square inch), and more preferably between 350 and 450 CPSI.

[0041] The wall thickness of the supporting structure is preferably between 2 and 11 mil (milli-inch), and more preferably between 3 and 9 mil, and even more preferably between 5 and 7.5 mil. In a most preferred embodiment, the wall thickness is between 6 and 7 mil, preferably approximately 6.5 mil.

[0042] The porosity of the wall of the supporting structure is preferably greater than 5%, and more preferably greater than 10%, and even better greater than 20%.

[0043] The cells formed preferably have a square shape, but can present other shapes such as triangular, sinusoidal, circular, hexagonal and similar.

[0044] Step 1B of the production of the coating suspension preferably comprises the following sub-steps: [0045] a first sub-step 1BX of providing a solvent; [0046] a second sub-step 1BY of the addition of an adsorbent to the aforementioned solvent to form a mixture; and [0047] a third sub-step 1BZ of the addition of a binder material to the aforementioned mixture.

[0048] In sub-step 1BY preferably one or more of the following and/or other materials are selected as an adsorbent: [0049] a zeolite, preferably a hydrophilic zeolite, but a hydrophobic zeolite is also possible—this zeolite can be faujasite zeolite type X for example, for example Zeolum F9 of Tosoh, or a mixture of zeolite type X and A; [0050] silica gel; [0051] activated alumina; [0052] activated carbon; [0053] metal-organic frameworks; [0054] carbon molecular sieve (CMS); [0055] an impregnated adsorbent; and [0056] a hybrid adsorbent.

[0057] The above list is not exhaustive and other materials are also possible according to the invention. The choice of adsorbent depends on what treatment the gas to be treated must go through, such as drying or the selective removal of other molecules such as oxygen or carbon dioxide for example, when using the adsorption means in a nitrogen generator or similar, whereby the gas to be treated can be compressed air for example.

[0058] The distribution of the particle size of the adsorbent is preferably such that D.sub.50 is less than 10 μm and more preferably less than 4 μm.

[0059] The aforementioned binder material that is added in the third sub-step 1BZ preferably contains an inorganic binder material such as: [0060] colloidal silica, for example Ludox-AS 40 of Grace Davison; [0061] alumina; and/or [0062] clay.

[0063] Moreover, if need be use can be made of an organic binder material such as: [0064] methyl cellulose; [0065] polymers such as acrylic resins, vinyl resins and similar; and/or [0066] a material from the cellulose group.

[0067] According to a possible characteristic of the invention, step 1B of the production of the coating suspension comprises the addition of one or more additives, such as an additive to affect the acidity (pH value), for example hydrogen chloride (HCl) to decrease the pH or ammonia (NH.sub.3) to increase the pH, and/or an additive to counteract foam formation. For example, but not strictly necessary, the pH value is brought between 9 and 11 and more preferably between 9.5 and 10.5.

[0068] The second sub-step 1BY of the addition of an adsorbent to the aforementioned solvent to form a mixture preferably comprises: [0069] the introduction of the adsorbent in powder form into the solvent [0070] the mixing of the adsorbent and the solvent during or after the introduction of the adsorbent in the solvent.

[0071] According to an additional preferred aspect of the invention, after mixing the adsorbent in the solvent, the adsorbent particles are reduced in size in order to obtain the aforementioned preferred particle size, for example by wet milling. Examples of wet milling are attrition milling, roll milling or immersion milling.

[0072] The coating suspension obtained after step 1B is preferably a shear thinning liquid, which upon the action of shear stress presents a reduced viscosity.

[0073] Step 2 of the method according to the invention, consisting of the application of the aforementioned coating suspension on the aforementioned supporting structure, preferably consists of flushing or perfusing the supporting structure with the coating suspension concerned.

[0074] Preferably the perfusion of the supporting structure is done from bottom to top or in other words in the opposite direction to gravity, for example by pumping means provided to this end that either pump the coating suspension upwards through the supporting structure or sucks up the coating suspension through the supporting structure, preferably until all channels through the supporting structure have been filled with coating material.

[0075] Then the pumping means can be switched off in order to let the surplus coating material flow out of the channels. Alternatively the operating direction of the pumping means concerned can be reversed such that an active evacuation of surplus coating material from the channels is obtained.

[0076] According to a particular preferred aspect of the invention, a part of the surplus coating material can be evacuated from the supporting structure by applying one or more pressure pulses of a purge gas through the channels of the supporting structure. An example of such a purge gas is air.

[0077] Good results are obtained in particular when using a shear thinning coating suspension with such active evacuation of the channels in the supporting structure.

[0078] After any removal of surplus coating material the coated supporting structure may be left to dry, for example in ambient conditions, until the solvent has largely evaporated. When water is used as a solvent, for example, this drying can be done in the surrounding air.

[0079] In a last step 3 of the method according to the invention the resulting supporting structure with coating, as obtained after step 2, is subject to a thermal treatment in order to sinter the coating.

[0080] During this thermal treatment the aforementioned resulting supporting structure is exposed to a temperature of preferably more than 400° C., and even more preferably more than 500° C., and in a most preferred embodiment a temperature of 550° C.

[0081] Of course numerous variant temperature variations may be applied during this thermal treatment. A non-limiting example is shown in FIG. 2, whereby the horizontal axis shows the time expressed in hours, while the vertical axis indicates the temperature expressed in degrees Celsius.

[0082] At the start time t.sub.0 of step three, the temperature is equal to the ambient temperature, in this example 20° C.

[0083] The temperature is raised slowly, in this case at a rate of 50° C. per hour, and in this example for a period of 10 hours 36 minutes. At time t.sub.1, i.e. 10 hours and 36 minutes after time t.sub.0, in this case the temperature will consequently have risen to 550° C.

[0084] Preferably the period of increasing temperature is followed by a period in which the temperature is kept constantly high, preferably above 400° C. and better above 500° C. In this non-exhaustive example the time interval in which the temperature is kept high is 1 hour. At the end of this time interval in which in this example the temperature is kept at 550° C. for 1 hour, the temperature will be reduced again, in this example at a higher rate than the temperature increase at the beginning of the heat treatment. The temperature can be decreased for example at a rate of 150° C. per hour, which in the example shown means that the time interval between t.sub.2 at the end of the period in which the temperature is kept practically constantly high, and t.sub.3 at the end of the temperature decrease to ambient temperature (in this example 20° C.), is only 3 hours and 32 minutes.

[0085] Starting with an ambient temperature of 20° C. and by adhering to the temperature variations as shown in FIG. 2 by way of a non-limiting example, the entire step 3 of the heat treatment will thus take 15 hours and 8 minutes.

[0086] As a method according to the invention yields a coating material with a very high mass density of adsorbent material and with a very good adhesion to the supporting structure (250 kg per cubic metre or more), such an adsorption agent obtained with the method according to the invention is extremely suitable for application in a drying device for drying compressed gas, as the increased dryer efficiency even enables the flow rate of gas to be dried that is guided through the drying device to be tripled. In other words, for the same flow rate of gas to be dried, a substantially smaller drying device can be used, which presents important ecological and economic benefits.

[0087] In order to be able to make the layer thickness bigger, according to a preferred aspect of the invention, the steps of applying the coating suspension and the thermal treatment of the whole of the supporting structure with the coating thereon is repeated one or more times, until the desired coating thickness on the supporting structure is reached.

[0088] The invention relates to a method for manufacturing an adsorption agent, either in the form of a drying agent for the adsorption of moisture or in the form of a different adsorption agent that can be used for selective adsorption, for example, such as in nitrogen generators or similar, because the adsorption agent is able to adsorb certain gas molecules such as oxygen, carbon dioxide and similar. By removing such gas molecules from compressed air for example, as is known, nitrogen can be generated.

[0089] The present invention is by no means limited to the embodiments described as an example and shown in the drawings, but a method according to the invention for manufacturing an adsorption agent can be realised in many ways, without departing from the scope of the invention.