Product Details

I. Features

During the unit start-up process, when the boiler ignites and the steam turbine is heated, more steam will enter the condenser. If a certain vacuum is not established within the condenser, the entry of steam and water into the condenser 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, deaeration pumps, and some low-pressure heaters, etc.) are in a vacuum state internally when operating normally.    Due to the loose piping and shell, air leaks in, which damages the vacuum of the condenser and endangers the safe and economic operation of the steam turbine. At the same time, the partial pressure of air in the condenser increases, leading to a higher dissolved oxygen content in the condensate, thereby exacerbating corrosion of the thermal equipment and pipelines. The presence of air also increases the heat transfer resistance in the steam absorber, affecting the cooling of the steam turbine exhaust by the circulating cooling water, and increasing the factory's electricity consumption. Therefore, it is necessary to continuously remove air from the condenser during its operation.

In summary, the vacuum system's purpose is①Establish condenser vacuum in the initial stage of the unit startup②Maintain the vacuum in the condenser during normal operation of the unit to ensure safe and economic operation. The main equipment for condenser vacuum extraction includes vacuum pumps and vacuum ejectors. The water jet vacuum ejector system is widely used in domestic large and medium-sized units due to its simple system and reliable operation.

Section 2: 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 different working media. The basic principle of these two types of pumps is the same; the only difference is the working medium. The working medium of the steam jet vacuum pump is pressurized steam, while for the water jet vacuum pump, it is pressurized water. Small capacity units often use steam jet vacuum pumps. For high parameter, large capacity units, since they all use slide parameter start-up 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 to1.2-1.6MPaThe steam jet vacuum pump under pressure is clearly uneconomical, and to recover the working fluid, a steam jet cooler also needs to be installed, which complicates the thermal system. Therefore, Currently, our country's large capacity units all utilize steam ejectors, which are primarily composed of working water inlet, working nozzle, mixing chamber, diffuser, 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, 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. This mixture is then expanded and returned to the water jet tank.

ThreeModel Description

Section 4: Product and Equipment Matching Table