Preparation method and skid block of micro-negative pressure and high concentration ammonia water

The invention discloses a preparation method of a micro-negative pressure and high concentration ammonia water. According to the preparation method, ammonia-containing steam exhausted from an ammonia still enters an ammonia-containing steam concentration unit first and is condensed and cooled with circulating cooling water; one part of the ammonia-containing steam is cooled as weak aqua ammonia and returns to the top platform the ammonia still; the other part of the uncondensed and un-cooled high concentration ammonia-containing steam enters a high-concentration ammonia water preparation unit; meanwhile, the high-concentration ammonia water preparation unit is stably operated under the pressure of -10-5kPa; the water from a tail gas washing and water replenishing unit enters the high-concentration ammonia water preparation unit and is used for cycle absorption to form high concentration ammonia water which is then discharged into an ammonia water tank. The operation temperature of the preparation method is lowered; the operation gas speed is increased; the resistance of the still is reduced and ammonia can easily escape from waste water; the mass transfer efficiency is improved; not only can ammonia water the concentration of which is above 20% be obtained, and also the energy consumption is remarkably reduced; the pressure stabilization of the ammonia still system is realized; the ammonia still process is safe and stable and the ammonia leakage does not occur within the whole device zone.