Jet vacuum pump

Product Details

I. Features

During the engine start-up process, when the boiler ignites and the steam turbine is warmed up, more steam will enter the condenser. If a certain vacuum is not established within the condenser, the entry of steam and water will cause the condenser to form positive pressure, damaging the equipment. Establishing a vacuum in the condenser is an indispensable condition for the steam turbine to start. Condenser and some low-pressure equipment (like condensate pumps, deaerating pumps, and some low-pressure heaters, etc.) are in a vacuum state internally during normal operation.    Due to the imperfect sealing of the pipeline and casing, air leakage occurs, which can destroy the vacuum of the condenser and threaten the safe and economic operation of the steam turbine. Simultaneously, the partial pressure of air in the condenser increases, causing an increase in dissolved oxygen in the condensed water, thereby exacerbating corrosion of thermal equipment and pipelines. The presence of air also increases the heat transfer resistance in the steam separator, affecting the cooling of the steam turbine exhaust by the circulating cooling water, leading to increased power consumption. Therefore, air must be continuously extracted from the condenser during its operation.

In summary, the vacuum system serves the purpose of...①Establish condenser vacuum at the initial stage of unit start-up②Maintain the condenser vacuum during normal operation of the unit to ensure safe and economical operation. The main equipment for vacuum extraction in the condenser includes vacuum pumps and exhaust blowers. The water-jet vacuum extraction system is widely used in domestic large and medium-sized units due to its simple design and reliable operation.

Section II: Structure and Working Principle of Water Jet Vacuum Pump

In modern power plants, the widely used vacuum pump is the jet vacuum pump, which boasts compact layout, simple structure, easy maintenance, reliable operation, and the ability to establish the required vacuum in a short period of time. Jet vacuum pumps can be divided into steam jet vacuum pumps and water jet vacuum pumps based on the working medium, with both having essentially the same principle; the difference lies in the working medium. The working medium for steam jet vacuum pumps is pressurized steam, while for water jet vacuum pumps, it is pressurized water. Small capacity units mostly use steam jet vacuum pumps. For high parameter, large capacity units, since they all use slide parameter startup methods, there is no possibility of having sufficient steam supply for the steam jet vacuum pump before the unit starts up. Moreover, it is necessary to use throttling from high-pressure steam to1.2-1.6MPaPressure steam injection vacuum pumps are clearly uneconomical, and in addition to that, a steam injection cooler needs to be installed for the recovery of working fluid, which also complicates the thermal system. Therefore, Currently, large-capacity units in our country are equipped with water jet vacuum pumps, which are mainly composed of working water inlet, working nozzle, mixing chamber, diffuser pipe, and check valve, etc.

Water Jet Vacuum Pump System. It consists of a water jet vacuum pump, a water jet pump, a water jet tank, and connecting pipes. The exhaust from each low-pressure heater, the condensate pump, and the bleed pump are collected through exhaust pipes and fed into the condenser, which is connected to the working chamber of the water jet vacuum pump. Water from the circulating water system or deep well is pressurized by the water jet pump (one in operation and one as a standby) and then injected into the water jet vacuum pump. The high-speed water jet emitted by the nozzle in the pump creates a high vacuum in the working chamber, extracting the gas-vapor mixture from the condenser. After expansion, this mixture returns to the water jet tank.

III.Model Description

IV. Product and Component Matching Table