Linde’s requirements for HCN
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“Both companies have relatively mature technologies and extensive engineering experience; they do not engage in unfair competition, but rather share the patent fees. Ruchi process: Absorption in H2S and CO2 separation towers ； Three-stage pre-cooling of the feed gas; the ammonia cooling process is complex ； A shell-and-tube heat exchanger is used, as it has low requirements for HCN and is easy to clean ； The process is relatively complex, it consumes a large amount of cooling capacity, and has high electricity consumption. Linde process: Segmented absorption of H2S and CO2 in separate towers ； Primary pre-cooling of the feed gas; ammonia cooling is simple ； A coil-type heat exchanger is used, as there are high requirements for HCN and such heat exchangers are difficult to clean ； The process is relatively simple, with low cooling energy consumption. ” Why is it said that Linde has high requirements for HCN! And Lurgi doesn’t have high requirements for HCN?
Under normal conditions, both parties have the same requirements regarding HCN; the lowest section of the absorption tower is used for removing NH3 and HCN. If the HCN content in the feed gas is particularly high, the design of the thermal regeneration system tower will differ (in such cases, the methanol/water separation tower will be designed as a partitioned tower).
The person who can provide the specific values for Linde and Lurgi’s requirements regarding HCN, including those for NH3, COS, etc
Please ask that expert to come and talk; I want to learn * it too.
As stated in a document, Global Process: The HCN concentration in recycled methanol is below 50 mg/l, while the NH3 concentration is kept below 20 mg/l
Linde’s low-temperature methanol washing technology takes into account the fact that NH3 generates ammonium sulfide during methanol washing, which reduces the quality of the CO2 product. Therefore, an ammonia content above 50 ml/m3 requires the addition of a wash tower upstream. Due to the high solubility of NH3 in water, the NH3 content reaching the methanol washing section after washing is significantly reduced. The ammonia-containing wastewater after washing is sent to the condensate flash tank of the shift system for treatment. HCN will accumulate in the circuit and cause corrosion. Due to the very low solubility of HCN in water and its high solubility in methanol, HCN is extracted from the alcohol/water separator after being sprayed into methanol and sent directly to the alcohol/water separation tower. When the HCN content in the feed gas reaches 20 ml/m3, it is necessary to add NaOH to the alcohol/water separation tower to treat the HCN, converting it and dissolving it in water, which is then sent to the water treatment system. The Luchi low-temperature methanol washing technology takes into account the high total levels of HCN, NH3, and higher hydrocarbons in the syngas outlet; it is difficult to absorb all of the HCN by using a separate water washing tower and adding only a small amount of methanol to prevent water from freezing (as too much methanol would be required to achieve complete absorption). For gasification processes with high levels of HCN, NH3, and polymeric hydrocarbons, Luchi divides the desulfurization tower into two sections: a pre-washing section and a main washing section. In the pre-washing section, HCN, NH3, and polymeric hydrocarbons are absorbed using a small amount of subcooled carbon-rich methanol solution. The use of a floating valve tower ensures high efficiency in the absorption of HCN, NH3, and polymeric hydrocarbons, resulting in complete treatment. Polymer hydrocarbons are separated in an extractor using water as the extractant, yielding a naphtha byproduct. Methanol containing water, HCN, NH3, a small amount of polymer hydrocarbons, CO2, and H2S+COS are stripped in an azeotropic tower; the HCN, NH3, polymer hydrocarbons, CO2, and H2S+COS obtained from this stripping process are sent to a sulfur recovery unit. The methanol-water solution containing HCN is sent to the methanol-water tower at the bottom of the azeotropic tower, treated with NaOH, and then sent to the water treatment system.
What kind of valves are generally used in the HCN process? Are there any special requirements for pipes and valves?