Jet vacuum pump

Product Details

I. Features

During the startup process of the unit, when the boiler ignites and the steam turbine is heated, more steam will enter the condenser. If a certain vacuum is not established in 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 up. Condenser and some low-pressure equipment (like condensate pumps, drainage pumps, and some low-pressure heaters, etc.) are in a vacuum state internally during normal operation.    Due to the lack of tightness in the pipeline and casing, air can leak in, thereby破坏 the vacuum of the condenser and endanger 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 to rise, which in turn intensifies the corrosion of thermal equipment and pipelines. 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 power consumption of the plant. Therefore, it is necessary to continuously extract the air from the condenser during operation.

In summary, the vacuum system's purpose is:①Establish condenser vacuum at the initial 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 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 quickly. Jet vacuum pumps can be divided into steam jet vacuum pumps and water jet vacuum pumps based on the working medium, with both having fundamentally the same principles but differing only in the working medium. The working medium of a steam jet vacuum pump is pressurized steam, while for a water jet vacuum pump, it is pressurized water. Small capacity units often use steam jet vacuum pumps. For high-parameter, large-capacity units, due to the use of slide parameter start-up methods, there is no possibility of having an adequate steam source to supply the steam jet vacuum pump before the unit starts up, plus the need to throttle high-pressure steam1.2-1.6MPaPressure steam injection vacuum pumps are clearly uneconomical, and to recover the working fluid, a steam injection cooler must also be installed, 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, diffuser, and check valve, etc.

Water Jet Vacuum Pump System. It consists of a water jet vacuum pump, water jet pump, water jet tank, and connecting pipes. The exhaust from each low-pressure heater, condensate pump, and blowdown pump is 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 water jet tank, sourced from circulating water or a 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. This mixture is then expanded and returned to the water jet tank.

ThreeModel Description

Section 4: Product and Component Matching Table