Feed cooling

A final mode of heat transfer in tubular reactors is the feed-cooled reactor, where the hot products from the reactor are cooled by the feed before it enters the reactor. As shown in Figure S-22, the cold feed in the jacket is preheated by the reaction in the inner tube or a heat exchanger is used for this purpose before the reactor. Temperature profiles for feed cooling are shown in Figure 5-22. 

Figure 5-22 Temperature profiles in a wall-cooled reactor with countercurrent feed cooling.

The temperature of Ihe cooling medium shonld be at least as cool as the feed. Cooling should proceed until the bed has cooled to within a reasonable range (20°C) of the adsorption conditions. 

This type of unit features the main steps encountered in partial condensation. The available gas mixture, previously dried on molecular sieves, is cooled to around — 120 C by heat exchange in a series of piaicexchangers operating in countercurrent flow on the cold purified products, and is then introduced at the bottom of a tray column with a downflow of liquid methane. The operation takes place at a pressure of abont 1.6.10 Pa absolute. It yields hydrogen with a purity better than 98.5 per cent volume, and which contains less than 10 ppm of CO. After expansion and partial vaporization, the extract feeds a distillation colnmn operating at 0.2. 10 Pa absolute, which separates the carbon monoxide at the top with a yield of at least 80 per cent at a purity over 99 per cent volume, and liquid methane at the bottom. This methane provides reflux to the scrubbing column and partly to the feed cooling uuiL... 

Improvements in the removal of water and carbon dioxide from the feed air to an air separation plant also reduced costs. The feed air to a cryogenic air separation plant must be dehydrated and the carbon dioxide removed otherwise, as the feed cools to cryogenic temperatures, these contaminants will condense, freeze, and plug heat exchanger passages, thereby shutting down the plant. 

Raw water and treated water (for process, boiler feed, cooling tower make-up). Catalyst for replacing at least 15-20 % of the quantity required for full replacement. 

Reflux vessels feed cool liquid to columns and vessels. Therefore, during an emergency, the reflux system will generally be kept in operation to ensure that heat continues to be removed. The reflux vessel and its associated pumps and piping should be protected against external fire, either with fireproofing or water sprays. 

Power (kW-hr/barrel of feed) Cooling water (gal/barrel of feed)... 

Solution Feed cool air throug i diaphragms. No rotating components affected, just the diaphragms. Rows 3 and 4 had compressor delivery air, row 5 had intermediate stage compressor air from bleed valve. 

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