Steam compressor

The invention relates to a steam compressor, and mainly solves the problem of equipment faults caused by emulsification of lubricating oil in a transition box or pollution of volute steam due to weaker tightness of a traditional steam compressor. The steam compressor comprises a base, a motor, a shell, a volute, a transition box and a main shaft; a separation plate is arranged between the shell and the volute; the main shaft penetrates through the transition box and the separation plate to connect with a blade shaft; an accommodating cavity is formed between the separation plate and the transition box; a sealing ring is arranged between the separation plate and the transition box, and coats the main shaft; two end surfaces of the sealing ring are respectively matched with the separation plate and the transition box; a first spiral groove and a second spiral groove are formed in the sealing ring; and a sealing cavity is formed between the sealing ring and the transition box. The steam compressor adopts a sealing structure, solves the leakage problem of the volute and the transmission box of the compressor, effectively improves the production efficiency, and prevents emulsification of the lubricating oil in the transition box, pollution of steam in the volute by the oil and leakage of precious gas or poisonous and flammable gas.