Gas-sealed vacuum pump

Product Details

I. Features

During the boiler startup process and when the steam turbine is warmed up by the incoming steam, 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 develop positive pressure, damaging the equipment. Establishing a vacuum in the condenser is an indispensable condition for the steam turbine to start up. 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 pipes and casings, 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 thermal equipment and pipelines. The presence of air also increases the heat transfer resistance in the vacuum receiver, affecting the cooling of the steam turbine exhaust by the circulating cooling water, increasing power consumption. Therefore, it is necessary to continuously remove the air from the condenser during its operation.

In summary, the vacuum system's function is①Establish condenser vacuum in the early stage of unit startup②Maintain the condenser vacuum during normal operation of the unit to ensure safe and economic 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 the basic principle of both being the same; the only difference is 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, due to the use of slide parameter startup methods, there is no possibility of sufficient steam supply for steam jet vacuum pumps before the unit starts up. Additionally, it is necessary to use throttling from high-pressure steam to...1.2-1.6MPaThe steam jet vacuum pump under pressure is obviously very uneconomical, and it also requires the installation of a steam jet cooler for the recovery of the working fluid, which complicates the thermal system. Therefore, Currently, our country's large capacity units all utilize water jet vacuum pumps, which are mainly composed of working water inlet, working nozzle, mixing chamber, expansion tube, 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 spare) 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.

Section 3:Model Description

Section 4: Product and Equipment Matching Table