The first stage of spraying liquid supplement in the first recovery operation area of Beiying Coking Plant is directly taken from the mechanized clarifier, after the spraying liquid is operated in the initial cooler, the condensate directly returned to the mechanized clarifier, four liquid filling positions are set vertically in the middle and lower part of the clarifier. The original intention of the design is to adjust the opening and closing of the make-up valve to replenish the spraying liquid according to the change of the oil-water layer height in the mechanized clarifier, however, the height of oil and water layer stably and intuitively can not measured, the actual production, which leads to the excessive proportion of ammonia water added by spraying liquid of primary cooler, and the effect of naphthalene washing of the primary cooler is poor, and it brings large heat load to the primary cooler, which affects the temperature control after the primary cooler. In view of the control defects of primary cooler one-stage spraying in actual production, the process route of condensate in primary cooler was improved to reduce the heat load of the primary cooler and stabilize the ratio of the spraying liquid.