Jet vacuum pump

Product Details

I. Features

During the unit start-up process, when the boiler ignites and the steam turbine is preheated, more steam will enter the condenser. If a certain vacuum is not established in the condenser, the steam and water entering 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, drain pumps, and some low-pressure heaters, etc.) are in a vacuum state internally when operating normally.    Due to the loose piping and casing, air leaks in, thereby destroying the vacuum of the condenser and endangering 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 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, increasing the power consumption of the plant. Therefore, air must be continuously extracted from the condenser during operation.

In summary, the vacuum system's function 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 ejectors. The water jet ejector vacuum extraction 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. The principles of these two types of pumps are essentially the same, with the only difference being 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, since they all use slide parameter startup methods, it is impossible to have sufficient steam supply for steam jet vacuum pumps before the unit starts up. Additionally, it is necessary to use throttling from 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, 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, water jet pump, water jet tank, and connecting pipes. The exhaust from each low-pressure heater, the condensate pump, and the drain pump's exhaust are collected into a condenser via exhaust pipes, which is connected to the working chamber of the water jet vacuum pump. Water from the circulating water system or deep well is boosted by the water jet pump (one in operation, one as a standby) and then fed into the water jet vacuum pump. The high-speed water jet emitted by the nozzle in the pump generates a high vacuum in the working chamber, extracting the gas-vapor mixture from the condenser. After expansion, this mixture returns to the water jet tank.

Section 3:Model Description

Section 4: Product and Equipment Matching Table