Low-temperature methanol washing HCN control

First, let’s examine the absorption of the various components of the changing gas in methanol: the approximate absorption coefficients of different gases in methanol at a partial pressure of 0C and 1 bar. The dimension of the absorption coefficient is Nm3/(m3·20°C·bar). Gas composition, absorption coefficients: HCN 2000, NH3 400, H2S 30, COS 20, CO2 6, CH4 0.5, CO 0.2, N2 0.15, H2 0.1. It should be noted that the solubility of CO, N2, and H2 is practically independent of temperature, whereas the solubility of other gases increases as the temperature decreases. A notable consequence of this fact is that the loading of a specific gas component in liquid methanol is almost proportional to its partial pressure in the gas phase. It is easy to see that the above figures also mean that: 1. In the thermal regenerator, COS and CO2 are easier to remove than H2S and even HCN. 2. The extremely high solubility of HCN and NH3 allows them to be removed in the pre-washing section of the absorption tower using a solvent at a very low flow rate. After understanding the above information, proceed with the process. The pre-washed methanol that has absorbed HCN is heated and then fed into the thermal regeneration tower, where it is vaporized under the action of methanol vapor; thereafter, it accumulates at the bottom of the thermal regeneration reflux tank through condensation. To avoid corrosion, the HCN content in thermoregenerated methanol should be kept below 50 mg/l.

Is the second floor the Lu Zi craft shop? Part of the hydrocyanic acid is removed in the ammonia scrubber and discharged through wastewater to the sewage treatment system; the rest is likely expelled through methanol waste at the top of the thermal regeneration tower. Of course, there is also circulation within the system, and to control this circulation it is necessary to regulate the amount of water used in the ammonia scrubber, the amount of methanol used for pre-washing in the absorption tower, and the amount of methanol waste discharged

Thermoregenerative lean methanol controls HCN at 50 mg/l

It’s probably difficult for ordinary companies to analyze HCN; even the institutions nearby are unable to do it, claiming that monitoring is required. In fact, many institutions simply cannot conduct such analyses. Which units can produce it? Please advise on the method.

The friend on the 2nd floor analyzed it very thoroughly: one method is to remove it through the ammonia washing tower, and accumulation tends to occur in the thermal regeneration tower. A portion can be removed through the wastewater from the methanol-water separation tower; in addition, a portion can be removed along with ammonia by replacing some of the methanol.

HCN content: <5 ppm, 5–20 ppm; after neutralization with alkali, it is incinerated； >20ppm, main scrubber tower with pre-scubbing section.