Coal gas vacuum potassium carbonate desulfurization and alkali-washing apparatus and method

The present invention relates to the field of coke oven gas desulfurization and discloses a coal gas vacuum potassium carbonate desulfurization and alkali-washing apparatus and a coal gas vacuum potassium carbonate desulfurization and alkali-washing method. The apparatus comprises a desulfurization tower, a rich liquid tank, an alkali-washing liquid supply system and a rich liquid desorption system, wherein the alkali-washing liquid supply system comprises an alkali-washing solution tank and a KOH solution storage tank. The method comprises: mixing desalted water with a KOH solution to prepare an alkali-washing solution; adding the alkali-washing solution into an alkali-washing section of the desulfurization tower and performing coal gas washing on the alkali-washing solution; returning the recycled absorbing liquid to an alkali-washing solution slot to mix with with the supplemented desalted water and KOH solution; introducing excessive absorbing liquid into the rich liquid tank through an absorbing liquid production tube and then introducing excessive absorbing liquid into the rich liquid desorption system to desorb with the rich liquid at an absorption section to form a lean liquid; and returning the lean liquid to the absorption section of the desulfurization tower for recycling. The whole flow realizes the internal recycle of desulfurization and alkali-washing, not only has relatively high desulfurization efficiency, but also avoids adverse effects,due to the fact that the alkali-washing section absorbing liquid enters a biochemical waste water treatment system, on production and operation of the system.