Special Electro-Hydraulic Valve for Hydro-Viscous Drive Used in Thermal Power Generation Plant

When applied on the pulverized coal blowers or water-feeding pumps which are driven by huge electrical motors in one thermal power generation plant, acting as a kind of the soft start-up device, hydro-viscous drive (HVD) can help to save a lot of energy. The principle and structure of HVD is introduced in the paper. Through theoretical analysis of the HVD set start-up steadiness, the conclusions were obtained that the non-linearity of the pressure performance curve and dynamic pressure instability of the pilot-operated electro-hydraulic pressure relief valve, which is used for the HVD speed regulating purpose and usually works within micro flow-rate and low oil pressure state, are the main causes of the poor start-up steadiness. So a special speed regulating valve for HVD set is developed, with which the start-up steadiness of HVD set is much improved.