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, deaerating pumps, and some low-pressure heaters, etc.) are in a vacuum state internally during normal operation.    Due to the loose piping and casing, air leaks in, thus破坏ing the vacuum of the condenser and threatening the safe and economic operation of the steam turbine. At the same time, the partial pressure of air in the condenser increases, causing the dissolved oxygen content of the condensate water to rise, which further intensifies corrosion of the thermal equipment and piping. The presence of air also increases the heat transfer resistance in the absorber, affecting the cooling of the steam turbine exhaust by the circulating cooling water, increasing the factory's power consumption. Therefore, it is necessary to continuously remove air from the condenser during operation.

In summary, the vacuum system's function is:①Establish condenser vacuum at the early stage of unit startup②Maintain the condenser vacuum during normal unit operation to ensure safe and economic operation of the unit. The main equipment for vacuum extraction of 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 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 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 similar principles but differing 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 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 enough steam supply for the steam jet vacuum pump before the unit starts. Moreover, it is necessary to use throttling from high-pressure steam to1.2-1.6MPaPressure steam ejector vacuum pumps are obviously very uneconomical, and to recover the working fluid, a steam ejector cooler must also be installed, which complicates the thermal system. Therefore, Currently, large-capacity units in our country all use 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 Vacuum System. It consists of a water jet vacuum pump, water jet pump, water jet tank, and connecting pipes. The exhaust gases from each low-pressure heater, condensate pump, and 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 backup) 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, after expansion, returns to the water jet tank.

III.Model Description

Section 4: Product and Equipment Matching Table