CLIAMS:1. A method for providing zero attrition in a pressure swing adsorption system, said method comprising the following steps:

• installing an apparatus on the adsorption bed of a pressure swing adsorption system;

• filling adsorption pellets in a hopper of said apparatus, through an opening in the upper portion of said hopper;

• determining the purity level of the affinity gas and/or particle escape during the adsorption phase in the form of particle dust exiting said pressure swing adsorption system;

• opening at least one valve of said apparatus and ejecting the adsorption pellets into the adsorption bed of said pressure swing adsorption system, in case where the purity level of the affinity gas falls below the predetermined level and/or particle dust exits said pressure swing adsorption system;

• re-filling adsorption pellets in said hopper of said apparatus, through the upper portion of said hopper.

2. An apparatus for providing zero attrition in a pressure swing adsorption system, said apparatus comprising:

• a hopper adapted to hold adsorbent pellets, said hopper comprising an upper portion extending into a lower portion in an operative vertical configuration, wherein the average diameter of said upper portion is more than the average diameter of said lower portion;

• a first flange attached to the open top of said upper portion of said hopper;

• a second flange attached to the open bottom of said lower portion of said hopper, wherein said second flange is adapted to be fitted to a complementary flange on a pressure swing adsorption system, to continuously feed adsorption pellets into said pressure swing adsorption system;

• a plurality of valves mounted on said second flange and adapted to eject the adsorption pellets into said pressure swing adsorption system. ,TagSPECI:TECHNICAL FIELD
The present disclosure relates to solid – gas adsorption and in particular to pressure swing adsorption units.

BACKGROUND
Adsorption is a phenomenon in which molecules in fluid phase are attracted to the surface of a solid, commonly referred to as an adsorbent. Adsorbents are generally porous materials having a large surface area per unit mass. This phenomenon is usefully implemented in the separation of a particular gas from a mixture of gases, under pressure, using suitable adsorbent materials. This phenomenon is more commonly used in pressure swing adsorption (PSA). The adsorbent could be of any type like carbon molecular sieve, silica, zeolite and the like.
PSA-based processes rely on the fact that under high pressure, gases tend to be attracted to solid surfaces, or get "adsorbed". The higher the pressure, the more is the gas adsorbed; when the pressure is reduced, the gas is released, or desorbed. The PSA process can be used to separate gases in a mixture using suitable adsorbents, as different gases tend to be attracted to different solid surfaces, either more or less strongly.
In a typical PSA system, a multi component gas at a high pressure is passed through multiple adsorption beds so as to adsorb one strongly attracted component, also referred to as affinity gas, and to pass on the other components of the gaseous mixture. For example, in order to remove oxygen from a mixture of gases, the mixture is forced under high pressure into a tank filled with zeolite as the adsorbent material. Similarly, in order to remove nitrogen, the mixture is forced into a tank filled with carbon molecular sieves. Both of these adsorbing materials capture the gas that has affinity for them onto their porous surface. When the bed reaches the end of its capacity to adsorb the affinity gas (saturation), it can be regenerated by reducing the pressure, thereby releasing the adsorbed affinity gas. It is then ready for another cycle of producing an environment enriched with the desired affinity gas.
The extracted gases are used in various applications. Nitrogen enriching PSA systems, for example, mainly cater to the needs of process units, utilities and offsite facilities in an onshore gas terminal. The growing nitrogen demand requires the development of highly efficient separation processes for nitrogen production from various feed mixtures. However, ever since the inception of this technology, the adsorption/desorption units of the PSA units endure continuous adsorbent attrition during operation. As the pellets of the adsorbents become fine dust powder, they tend to escape into the ambient air during desorption phase, posing serious environmental and health concerns. Further, a bulging of the filtration systems is also witnessed. To cope with the attrition of the adsorbents and to keep the process smooth, a fresh quantity of adsorbent stock is always required to be kept on standby. Particle attrition in adsorption column is commonly attributed to the quality of particle and design of adsorption chambers.

OBJECTS

Some of the objects of the present disclosure, which at least one embodiment discussed herein satisfies, are as follows:
It is an object of the present disclosure to provide an arrangement that continuously makes up for adsorbent attrition in a PSA unit during operation without the need to dust off adsorbent pellets.
It is also an object of the present disclosure to stop fluidization of the adsorbent particles in the fluidized bed of the PSA unit.
It is an object of the present disclosure to maintain the purity of the resultant affinity gas to above 99.6%
It is an object of the present disclosure to cause negligible loss of adsorbent particles into the ambient.
Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.

Brief Description of the Drawings

The subject matter of the present disclosure will now be explained in relation to the accompanying non-limiting drawings.
Figure 1 Illustrates a hopper arrangement for placement on the PSA adsorption bed, in accordance with an embodiment of the present disclosure.

Detailed Description
The disclosure will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The subject matter of the present disclosure overcomes the drawbacks in the state of the art by providing a continuous flow of adsorbent pellets in the fluidized bed of a PSA unit. The above mentioned objectives are fulfilled by providing a novel hopper arrangement as disclosed herein.
As shown in FIGURE 1, the hopper arrangement 100 comprises a cylindrical unit (102a and 102b), having an upper portion 102a extending into a lower portion 102b in an operative vertical position. The hopper arrangement 100 has a thickness sufficient to bear the load of the adsorbent pellets 104 fed through it. The present invention is not restricted to the position of the hopper arrangement. In an embodiment, the average diameter of the upper portion 102a is more than the average diameter of the lower portion 102b and gives the hopper an inverted bottle appearance with its neck attached to the PSA unit. The open top of the upper portion 102a extends outwardly from the vertical at its uppermost end 105a and has a first flange 106 attached thereto, for example, by welding. Likewise the open bottom of the lower portion 102b extends vertically from the vertical at its lowermost end 105b and has a second flange 108 attached thereto. The first and the second flanges have threaded holes 110 and 112. The first flange 106 is bolted to a dummy flange 114 from above through threaded holes 110. In an embodiment, a total of 8 holes are provided on the first flange 106. Further, the second flange 108 is bolted on top of an adsorption bed of a PSA unit (not shown), through threaded holes 112.
In an embodiment, the diameter of the uppermost end 105a of the upper portion 102a is about 230mm and the first flange 106 attached to the uppermost end 105a has a diameter of about 1000mm. Further, the diameter of the lowermost end 105b of the lower portion 102b is about 50 mm, while the second flange 108 attached to the lowermost end 105b has a diameter of about 170mm.
In an embodiment, the hopper arrangement 100 has a length L of about 600mm, in which the upper portion 102a has a length L1 of about 460mm or more while the length L2 of the lower portion 102b is at least 140mm. The upper portion 102a takes feed of the adsorbent pellets 104 from the open uppermost end 105a and buffers the same inside the whole of the length L of the hopper arrangement 100. The adsorbent pellets 104 are ejected into the PSA bed through the open end of the lower portion by opening a valve (not shown).
In operation, the hopper arrangement can be installed operatively above or to the side or on the adsorption bed of the PSA unit. The hopper arrangement 100 is filled with the adsorbent pellets 104. The adsorbent pellets 104 are stored inside the whole of the hopper arrangement 100 as a buffer stock and remain ready to be fed into the adsorption bed. If during the adsorption process inside the PSA unit, the adsorbent pellets present in the adsorption bed are used up or their pores are filled with gas or are filled with particle dust, all of which may cause the level of affinity gas purity to go down, the valve in the hopper arrangement 100 opens and the adsorbent pellets 104 flow into the PSA unit via the lowermost end 105b. In this way, a continuity of the adsorbent pellets in the adsorption bed is maintained and the fluidization of the adsorbent particles in the adsorption bed is almost eliminated. This also helps to maintain the purity of the resultant affinity gas, from the exit of the PSA unit, to above 99.6%.

Technical Advancements and Economic Significance
The hopper arrangement, in accordance with the present disclosure described herein above, has several technical advantages including but not limited to the realization of:
• Continuous flow of adsorbent pellets in the pressure swing adsorption unit;
• Elimination of adsorbent dusting; and
• Increase in the purity of the resultant affinity gas to above 99.6%.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.