1. Product use and characteristics Shaft seal gas extraction heater is an important equipment in the steam turbine shaft seal system, used to pump the steam overflow from the steam turbine shaft seal, to avoid discharge into the steam engine room or into the oil system, at the same time to recover the steam waste heat, to ensure the safe and economic operation of the steam turbine unit.
    

The condensing steam turbine, pumping steam turbine and back pressure steam turbines of thermal power plants and industrial and mining enterprises have shaft sealing device to avoid steam overflow.structurally. Shaft seal is close to the bearing. Under the negative pressure of the bearing chamber. The steam from the shaft seal can easily enter the bearing seat. This is the main way of getting water in the steam turbine oil. In the steam turbine thermal system design. There are two types of shaft sealing system: open table type and closed type. Open shaft seal system is used for old steam turbines and many current medium and small steam turbines in this design mode, the shaft seal outer chamber pressure is higher than one atmospheric pressure. The leakage of steam overflows directly into the atmosphere. Steam is easy to be sucked into the bearing seat, and the operation is inconvenient, the latter type is a closed shaft sealing system. That is, in addition to the shaft and sealing steam suction and cooling device, it is mostly used in large and medium steam turbine units in China. Specifically, it is to use the suction device, suction the shaft seal outside the overflow steam, make it into the heater to heat the condensate water. At the same time, the shaft seal steam is cooled into condensed water, which is recovered by the condenser because the shaft seal outer is negative pressure, and the steam no longer overflows. However, the current steam turbine manufacturers, the production of the pumping heating device are produced according to the traditional design of each manufacturer, a wide variety of production, most of the pumping and heating two parts separate, and the pumping device is divided into shaft seal fan type, low pressure shootingWater pump type, water pump under the residual type and suction type, and add a separate shaft seal heater, the above type of device system structure is complex, operation lock. For medium and small wheel units

This product "shaft seal pumping heater" is a device that combines the two processes of shaft seal extraction and heating condensate water. It has the advantages of unique structure, simple system and stable operating condition, and because of its shaft seal pumping device is adjustable, ensures the reliability of operation, and avoids the water in the oil.

3. structure

The shaft seal heater is used in the steam turbine shaft seal system. Its main function is to use condensate water to cool the shaft seal and the valve stem of the high and medium pressure main steam regulating valve, form and maintain a certain vacuum in the steam side chamber of the shaft seal heater, and prevent steam leakage from the shaft seal end. The steam in the mixture into water to recover the medium. The heat of the steam-gas mixture is transferred to the condensed water, which improves the economy of the steam turbine thermal system. At the same time, the temperature of the mixture is reduced to the temperature allowed for the long-term operation of the shaft seal fan.

4. Product technical specification

5. Installation of the shaft seal air extraction heater

1. Thermal power system layout

The arrangement of the shaft seal extraction heater in the thermal system is shown in Figure 2. Steam turbine before and after the shaft seal escape steam interface with pipe, and make it with the shaft seal suction heater before the heating interface, shaft seal pump heater from condensation gas, directly by the exhaust pipe into the atmosphere, before and after the heater water and by a V-shaped pipe into the low tank, from the condenser to condensate pipe and the inlet pipe, outlet pipe to the low pressure heater, in order to adjust, the water pipe without the shaft seal suction heater bypass pipe.

2. Notes for installation

① The device is arranged horizontally.

② In order to facilitate hydrophobic, the device adopts the arrangement above zero meter layer, which can be installed on the heater running layer, that is, on the platform between the zero meter layer of the running layer.

③ During installation, attention should be paid to the inlet and outlet position of the cooling water, not in reverse. The inlet position of the cooling water is located on the same side with the inlet of the shaft seal, and the outlet position of the cooling water is located on the same side with the injector.

④ Attention should be paid to the height of the V pipe, its design principle is: the height of the water column of the V pipe should be greater than the height of the water column in the negative pressure of the connected container.

⑤ The air discharge outlet should be discharged directly into the atmosphere, and the pipeline discharge outlet can be arranged at the edge of the pipe outlet, with the principle of not affecting the passage of personnel.

⑥ Install a vacuum meter and a 0-100℃ temperature meter on the shaft seal steam inlet short pipe, and a 0-100℃ temperature meter for each of the inlet short pipe of cooling water.

⑦ Hydrostatic test: the product has been tested hydraulic test before the factory, but before the installation and operation should still be repeated according to the principle of the Technical Specification for Electric Power Construction and Acceptance (steam turbine unit), the water pressure of the steam chamber 0.2MPa, water pressure 1.3MPa, five minutes is qualified.