Product Details

I. Features

During the unit startup process, 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 water and steam 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, sludge 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 compromising the safe and economic operation of the 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 intensifies corrosion on thermal equipment and piping. The presence of air also increases the thermal resistance in the heat exchanger, affecting the cooling of turbine exhaust steam by the circulating cooling water, thereby increasing the factory's electricity consumption. Therefore, it is necessary to continuously extract air from the condenser during its operation.

In summary, the vacuum system's purpose is:①Establish condenser vacuum at the early stage of unit startup②Maintain the vacuum of the condenser during the normal operation of the unit to ensure the safe and economical operation of the unit. The main vacuum extraction equipment for the condenser includes vacuum extractors and vacuum pumps. The water-jet vacuum extractor 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, convenient 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 different working mediums. These two types of vacuum pumps share the same basic principle, with the only difference being the working medium. The working medium of the steam jet vacuum pump is pressurized steam, while the working medium of the water jet vacuum pump is pressurized water. Small capacity units typically use steam jet vacuum pumps. For high parameter and large capacity units, due to the use of slide parameter start-up methods, it is impossible to have sufficient steam supply for the steam jet vacuum pump before the unit starts up. Moreover, it is necessary to use throttling from high-pressure steam to...1.2-1.6MPaPressure steam injection vacuum pump is obviously uneconomical, and it also requires the installation of a steam injection cooler for the recovery of working fluid, which complicates the thermal system. Therefore, Currently, large capacity units in our country all utilize 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 System. It consists of a water jet vacuum pump, a water jet pump, a water storage tank, and connecting pipes. The exhaust from each low-pressure heater, the condensate pump, and the bleed pump 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, lifted to pressure by the water jet pump (one in operation and one standby), is 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 to extract the gas-vapor mixture from the condenser. This mixture, after expansion, returns to the water storage tank.

III.Model Description

Section 4: Product and Equipment Matching Table