When is the appropriate time to introduce the primary seal air in a centrifugal compressor?

It can be introduced simultaneously with the gas being conveyed, but do not start operation until the pressure reaches the level required for sealing, in order to prevent damage to the sealing surfaces.

It should be injected before startup; as long as the pressure behind the pressure relief valve is properly controlled, not much nitrogen will enter the cylinder. The nitrogen consumption of typical units is around 5 M3/H

If it is not installed in advance, process gas will leak out during the compression of the solid gas, posing a danger

Sealing gas is supplied when performing nitrogen purging or solid-gas ramming at 3KG in centrifugal compressors.

It must be put into operation before lubricating oil is supplied to the system; otherwise, when the lubricating oil enters the dry gas seal, it will damage the seal, as the sealing surfaces of the dry gas seal do not allow any impurities to get in!

20 minutes before the startup of the unit’s oil pump, the isolation gas is brought online to operate normally. 20 minutes before the compressor starts up and pressurizes, the primary seal gas is activated to operate normally, and 5 minutes before startup, the secondary seal gas is put into operation; furthermore, the pressure of the secondary seal gas shall not exceed that of the primary seal gas

The sequence for putting the dry gas seal system into operation is as follows: before the unit starts operating with oil, isolate air is introduced to prevent lubricating oil from entering the dry gas seal system and contaminating the seal surfaces； Before pressurization, the first-stage seal of the unit is used; its pressure is controlled by the pressure difference between the first-stage seal and the balance line. Generally, the pressure of the first-stage seal is kept 0.2 MPA higher than the pressure in the balance line. The gas for the second-stage seal And the flare line for the first-stage seal come into operation before the compressor is started

Before starting the lubricating oil, turn on the isolation air (compressed air) first; otherwise, it won’t work. . . . . . . . Think for yourself.

Sealing gas is introduced before filling with the process gas to prevent impurities carried in the process gas from entering the sealing surface.

Before the unit is put into operation, it is purged with nitrogen. In fact, it’s not necessary to use a gas seal; the purpose of using nitrogen is to prevent the leakage of toxic and harmful gases. At this point, nitrogen poses little risk, so it’s important but not urgent. It just needs to be put into use before you introduce process gas into the compressor. If it is a startup unit that uses nitrogen circulation for heating, then it can be put into operation after being pressurized with nitrogen

The person on the 8th floor covered it quite comprehensively.

Isolation gas should be introduced before oil transportation, while sealing gas is introduced at the compressor’s intake stage. 6# peijie_jun

1. Activate the rear isolation 10 minutes before starting the oil pump. 2. Introduce the secondary seal gas before trial running. 3. Introduce the primary seal gas before connecting to the gas supply

The sequence for putting the gas seal system into operation is as follows: After introducing isolation gas for at least 10 minutes, the unit’s oil system can be activated, in order to prevent lubricating oil from entering the dry gas seal system and contaminating the seal surfaces. The pressure of the isolation gas supply is 0.43 MPA; after passing through the pressure regulator, this pressure is reduced to 0.14 MPA； Before pressurization, the unit utilizes a primary seal, whose pressure is controlled by the pressure difference in the balance tube; generally, the pressure of this primary seal is kept 0.3 MPA higher than the pressure in the balance tube. Once that is in place, a secondary seal is activated, with its gas pressure ranging from 0.43 to 0.6 MPA. If the unit is not in a hurry to start up, gas can leak into the cylinder through the primary dry gas seal, thereby maintaining the pressure required for starting the unit.

Isolation gas is introduced 30 minutes before oil circulation, and primary sealing gas is supplied before starting up. The normal gas consumption rate is 5 m3/h; (the primary sealing gas in this factory is nitrogen along with process gas.) When connecting the gas supply to the system, it is switched to process gas, with the gas consumption rate controlled at 7 m3/h. The secondary sealing gas should be activated 5 minutes before starting the machine to ensure normal operation; moreover, the pressure of the secondary sealing gas must not exceed that of the primary sealing gas. It should be turned on before startup, and as long as the pressure is properly controlled using the pressure regulator, not much nitrogen will enter the cylinder. The nitrogen consumption of such machines is generally around 5 M3/H