Vertical pump and urea synthesis plant

A vertical pump, comprising:

• a rotary shaft;
• multi-stage impellers configured to rotate with the rotary shaft;
• a casing accommodating the multi-stage impellers;
• a mechanical seal provided in a penetration part of the casing for the rotary shaft;
• a balance sleeve for at least partially balancing a thrust force of the rotary shaft, the balance sleeve being positioned between a final stage impeller of the multi-stage impellers and the mechanical seal in the penetration part for the rotary shaft;
• an intermediate chamber provided between the rotary shaft and the casing and provided on an opposite side of the multi-stage impellers across the balance sleeve in an axial direction of the rotary shaft, the intermediate chamber communicating with an intermediate stage impeller among the multi-stage impellers;
• a low pressure chamber provided between the rotary shaft and the casing and provided adjacent to the mechanical seal in the axial direction, the low pressure chamber communicating with a low pressure side compared to the intermediate chamber;
• and
• a partition wall part dividing the intermediate chamber and the low pressure chamber.