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Liquid Distributor with Floating, Slotted Tubes

IP.com Disclosure Number: IPCOM000019389D
Publication Date: 2003-Sep-12
Document File: 4 page(s) / 307K

Publishing Venue

The IP.com Prior Art Database

Abstract

Packed distillation columns require uniform liquid distribution within the packing for optimum performance. Typically, liquid distributors, whose main function is to irrigate the packing uniformly above a packed section, consist of a Primary Distributor and a Secondary Distributor. The Primary Distributor (or "Pre-distributor") takes liquid from a collection pot and feeds it to the Secondary Distributor, which irrigates the packing directly. Typically, liquid is transferred from both the Primary and Secondary Distributors by means of a plurality of holes, orifices, slots, or weirs. Because the flow rate of liquid through or over holes, orifices, slots, or weirs depends on the liquid level on their upstream side, the liquid level must be approximately constant to achieve uniformity of irrigation.

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Liquid Distributor with Floating, Slotted Tubes

Packed distillation columns require uniform liquid distribution within the packing for optimum performance. Typically, liquid distributors, whose main function is to irrigate the packing uniformly above a packed section, consist of a Primary Distributor and a Secondary Distributor. The Primary Distributor (or “Pre-distributor") takes liquid from a collection pot and feeds it to the Secondary Distributor, which irrigates the packing directly. Typically, liquid is transferred from both the Primary and Secondary Distributors by means of a plurality of holes, orifices, slots, or weirs. Because the flow rate of liquid through or over holes, orifices, slots, or weirs depends on the liquid level on their upstream side, the liquid level must be approximately constant to achieve uniformity of irrigation.

In practice, the liquid head in a Primary or Secondary Distributor may vary across the cross-section of the column. Common cases in which this would occur include that of an improperly installed distributor, such that one side of the distributor is located higher in the column than the other, or the case of a wide column, in which liquid level gradients are created as the liquid flows out from the center of the distributor toward the column wall. An extreme example is the case of a shipboard column installation, in which the column may be expected to tilt from side to side by as much as 30 from vertical on a periodic basis. If a shipboard column were fitted with a conventional liquid distributor relying on liquid level above an orifice for uniform irrigation of the packing, the liquid level and flow rate variations across the distributor would be substantial. Column performance would suffer as a result. One potential solution to this problem would be to use very large liquid levels or high liquid pressures (attainable with a pump) to minimize the percentage variation in head as the column tilts. However, columns containing pumps or high liquid levels in a distributor are costly both to build (because they require pumps and subcoolers or taller columns and extra vessels) and to operate (because the higher volume of liquid means the column is less responsive to changes in process conditions).

One solution to the problems which arise when the liquid level in the distributor is not uniform is to make the liquid flow rate through the distributor orifices independent of the liquid level. To achieve this, a floating, slotted tube system is proposed, as shown in Figure 1. This system consists of a bottom tube fixed to the floor of a Primary or Secondary distributor, extending down below the floor and projecting above the floor vertically, and a slotted top tube, fitted with a float. The bottom tube should extend downward to a point just above the top of the packing when installed in a Secondary Distributor, thereby maintaining the irrigated location across any distance between the distributor and the packing....