Design of one Operation Unit - Essay Example

The technology currently accounts for more than 20% of air separations. In cryogenic distillation applied in this design, air is liquefied, and then fractionally distilled, separating the air into its constituents primarily nitrogen, oxygen and argon. This is a complex process that is the most common and efficient method of large scale oxygen production. It is also the most efficient method of storing oxygen. Liquid oxygen storage is six to eight times more efficient than high pressure cylinders.

The complexities and cool down requirements highly favour continuously operating production plants; this is not usually the mode of operation for field medical facilities. Liquid oxygen can be stored, but there is a loss rate that is dependent on the size of the container, the amount of liquid oxygen in the container, and the ambient temperature. Liquid oxygen cannot be stored for long term use. It is a simple matter to safely fill high pressure oxygen cylinders using liquid oxygen. Cryogenic air separation is currently the most efficient and cost-effective technology for producing large quantities of oxygen, nitrogen, and argon as gaseous or liquid products.

An air separation unit using a conventional, multi-column cryogenic distillation process produces oxygen from compressed air at high recoveries and purities. Cryogenic technology can also produce high-purity nitrogen as a useful by product stream at relatively low incremental cost. In addition, liquid argon, liquid oxygen, and liquid nitrogen can be added to the product slate for stored product backup or byproduct sales at low incremental capital and power costs. Capacity and product specification The designed system comprises of 3 columns with a length of 1 meter each.

Its ID is 3cm. The system is equipped with an automated control system for regulation of each cycle’s time to monitor and record rate of flow, system pressure, and temperatures of the columns. The designed system can be applied to an extensive range of absorbents and pressures in facilitating the adsorption process. The targeted optimal rate of flow of oxygen to be produce by the system is 80 lit/min. design specifications are illustrated in the tables below, Capacity table: Theoretical Model Fix layer and dynamic regime adsorption is often characterized by continuous fluid flow phase going via an adsorbent layer within a time variable process (Nexant Inc., 2010). This is theoretically represented in the diagram below: At the process start, free adsorbent layer volume is considered as filled up with a given component A which cannot be absorbed and further, the solid is “clean”, and does not have any absorbing component B.

Other assumptions made are that the gas is ideal; the absorbent layer has constant temperature, the section has constant speed, and that there is an insignificant pressure drop in the layer. This process is represented in a mathematical model which incorporates multiple equations referring to adsorbed component in volume element of height, fluid phase, and solid and the balance equation. These equations are illustrated hereafter, Product stands for mass transfer coefficient per absorbent layer’s unit volume.

The first two equations can be simplified using a modified time variable as follows, The equations can be solved simoultaneously with knowledge of limit conditions: At the start, adsorbed component concentration is zero at any point in the adsorption