Air Sealing 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 within the condenser, the entry of steam and water 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, sewage 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, thus破坏ing the vacuum of the condenser, 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 oxygen content in the condensed water, which exacerbates corrosion of the thermal equipment and piping. The presence of air also increases the thermal resistance in the heat exchanger, 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 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 operation of the unit to ensure safe and economic operation. The main equipment for vacuum extraction of the condenser 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 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 essentially the same principle; 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, since they all use slide parameter startup methods, there is no possibility of having 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...1.2-1.6MPaThe steam ejector vacuum pump under pressure is clearly uneconomical, and to recover the working substance, 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, expansion pipe, 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 blow-off pump is collected into a condenser via exhaust pipes, which is connected to the working chamber of the water jet vacuum pump. Water from the water jet tank, sourced from recirculating water or deep wells, is pressurized by the water jet pump (one in operation, one standby) and then fed into the vacuum pump. The high-speed water jet emitted from 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