Recovery from oxidant scrubbers

Fig. 6 Magnesium oxide regeneration and sulfur dioxide recovery section for a magnesium oxide scrubber. (From Ref.. )...

In methanol synthesis purge recovery, a water scrubber is also used with a similar purpose, and it too pays for itself in recovered methanol. The meth-anol/water mixture is simply sent to the existing crude methanol distillation column. Hydrogen recovered from this purge can result in energy savings or if additional carbon oxide is available, it can be used to obtain increased methanol production. PRISM separators have operated on stoichiometric as well as non-... 

A furnace similar to the Tomlinson kraft recovery furnace is used for the combustion of magnesium-based sulfite spent liquors. In this case, however, no smelt is obtained instead the base is completely recovered as magnesium oxide in dust collectors the sulfur escapes as sulfur dioxide and is absorbed from the combustion gases in scrubber towers. However, because magnesium hydroxide has a very low solubility in water, a complete recovery of sulfur dioxide meets difficulties. 

The raw gas from the partial oxidation contains soot, about 0.8 wt% of the hydrocarbon feed. Soot particles together with ash are removed mainly in the venturi scrubber downstream of the quench. The soot slurry from quench and venturi is sent to the metals ash recovery system (MARS) Figure 58. First the soot slurry is flashed to atmospheric pressure and then filtered, leaving a filter cake with about 80 % residual moisture. The filter cake is subjected to a controlled combustion in a multiple hearth furnace. Under the conditions applied, a metal oxide concentrate containing 75 wt% of vanadium, together with some nickel and iron, is obtained which can be sold to metal reclaimers. The MARS ist practically autothermal as the heat of combustion is sufficient to evaporate the moisture of the filter cake. 

Gases leaving the downdraft condenser are passed through a bubble-plate or packed water scrubber, where additional absorption of NO takes place. Laboratory studies [M2] indicate that the nitrogen oxide content can be reduced to from 0.1 to 0.5 percent with a residence time of 2 min in the condenser and water scrubber. The design of scrubbers for recovery of nitrogen oxides is described in standard texts, e.g., [P5]. 

DISPOSAL AND STORAGE METHODS can dilute, neutralize, or precipitate out phthalate salts for recovery dissolve in flammable solvent, such as alcohol, and atomize in suitable combustion chamber equipped with afterburner and scrubber liquid may be absorbed in dry earth, sand, or vermiculite, and placed in a sanitary landfill store in a cool, dry location separate from acids, strong oxidizers, alkalies, reducing agents, and moisture. 

A carbon dioxide sensor for monitoring levels in a closed exhalation anesthesia system was developed by Jordan (23). 7,10-dioxa-3,4-diaza-l,5,12,16-hexadecatetrol was prepared by mixing monoethanolamine, often used as a CO2 scrubber, with ethylene gylcol diglycidyl ether in a 2 1 ratio and was used as a coating. The respone was 391 Hz for 10% CO2, exposure time less than 30 sec, and complete recovery in less than 60 sec. No interferences were reported from nitrous oxide, halothane, or oxygen tested at normal anesthesia concentrations. 

Research and development efforts were focused on addressing several of the problems of the day. Sulfur oxides (SOx) were becoming more stringently controlled, and stack gas scrubbers or use of hydrodesulfurized gas oil feed were expensive options, so catalyst makers developed new products that worked in conjunction with a Claus unit to first reduce the sulfur to hydrogen sulfide and then recover it as elemental sulfur. Carbon monoxide, formed at the higher regenerator temperatures resulting from improved zeolite catalysts, needed to be oxidized to improve heat recovery, and additives were developed to accomplish this. Metals tolerance and octane improvement were needed as well, and producers vied with each other to address the needs of the market (85). 

Tokyo Electric-Mitsubishi Heavy Industries Process. The Tokyo Electric-Mitsubishi Heavy Industries (MHI) process is a wet oxidation-absorption system developed jointly by Tokyo Electric Power and MHI. This process was developed for treating clean flue gas (no SO,). The NO, is oxidized by O3 to N2O5, absorbed in H2O to form 8-10% HNO3, and then concentrated to a 60% acid solution in the byproduct recovery section. A calcium sulfite scrubber removes any excess ozone from the flue gas. In December 1974, a 33.3 MW q jv plant began operating. No operating results or costs have been published (Faucett et al., 1978). 

FIGURE 11.2 Scheme of the installation for the gas-phase oxidation of hydrocarbons used by the Celanese firm [263] (1) mixer, (2) heater, (3) reactor, (4) formaldehyde scrubber, (5) water scrubber, (6) distillation coiumn, (7) heat exchanger. (I) Hydrocarbon gas (11) air (111) cycle gas (IV) gas for the hydrocarbon recovery unit (V) gas for light products purification unit (VI) recycled formalin solution (VII) crude formalin for purification (VIII) formaldehyde from chemical products purification unit (IX) caustic soda to adjust the pH value. 

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