Product Details

I. Features

During the starting process of the unit, when the boiler ignites and the steam turbine warms 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 develop positive pressure, damaging the equipment. Establishing vacuum in the condenser is an indispensable condition for the steam turbine to start. The condenser and some low-pressure equipment (like condensate pumps, deaeration pumps, and some low-pressure heaters, etc.) are in a vacuum state internally during normal operation.    Due to the loose piping and shell, air leaks in, thereby destroying the vacuum of the condenser and posing a risk to 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, which exacerbates corrosion of the thermal equipment and piping. 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, thereby increasing the factory's electricity consumption. Therefore, it is necessary to continuously remove air from the condenser during operation.

In summary, the vacuum system's purpose is:①Establish condenser vacuum in the early stage of unit start-up②Maintain the condenser vacuum during normal unit operation to ensure safe and economic operation of the unit. 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 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 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. Moreover, it is necessary to throttle high-pressure steam to1.2-1.6MPaPressure steam jet vacuum pumps are clearly uneconomical, and in order to recover the working fluid, a jet cooler must also be installed, which 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, 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 drain 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, thereby extracting the gas-vapor mixture from the condenser. This mixture is then expanded and returned to the water jet tank.

III.Model Description

Section 4: Product and Equipment Matching Table