Equipment and process for reducing ammonia nitrogen indexes of coal gasification water system

Abstract

The invention relates to equipment and a process for reducing ammonia nitrogen indexes of a coal gasification water system. A graded and split steam stripping method is adopted; firstly, steam stripping is carried out on high-ammonia-nitrogen hardness-free condensate, and then the steam-stripped condensate is mixed with high-hardness grey water, so that the ammonia nitrogen indexes of the whole coal gasification water system are reduced, the steam stripping system is prevented from reducing the hardness by using alkali liquor and reversely adjusting the pH value by using acid liquor, and the operation cost and investment of the whole gasification device are greatly reduced; meanwhile, condensate generated by the high-pressure evaporation hot water tower, the low-pressure evaporation hot water tower and the vacuum flash separator enters the stripping tower in a temperature-level split manner for stripping and deamination, so that the consumption of low-pressure steam and the amount of discharged wastewater are also reduced; and finally, the steam stripping process nested in the grey water flash evaporation system, so that the ammonia nitrogen of the low-pressure grey water pipeline is reduced, the alkaline environment of the low-pressure grey water pipeline is improved, and the scaling rate of the low-pressure grey water pipeline is slowed down.

Description

technical field [0001] The invention relates to a device and a process for reducing the ammonia nitrogen index of a coal gasification water system. Background technique [0002] For coal gasification effluent, if the ammonia nitrogen value exceeds the acceptable index of the downstream sewage treatment device, the gasification wastewater needs to be pretreated to remove ammonia nitrogen. However, the total hardness in the gasification wastewater is relatively high, generally up to 1000 mg / L. If it is not treated with hard removal, it will cause serious fouling of the stripping unit and affect the normal operation of the equipment. [0003] Existing coal gasification wastewater pretreatment devices mostly use chemical hardening treatment, which is limited by the limitation of solubility balance, and it is impossible to reduce the total hardness in wastewater to a very low level, at most down to the calcium and magnesium ions corresponding to the solubility balance of wastewat...

AI Technical Summary

Problems solved by technology

Eventually, the salt content in the outgoing wastewater index will increase, which will affect the processing load of the crystallization device with high salt content;

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