What Is Aqueous Cleaning?

Flushing water is mainly used for safety (prevention of high-temperature flammable media leaks and fires), and to increase the service life of seals and packings. Flushing water can reduce the temperature near the seal gland (some sealed auxiliary seals are not resistant to high temperatures and need to be cooled down) , Or you will finish playing soon) Take away some of the heat, and at the same time you can rinse the leaked medium.

Mechanical seals are improving

Washing water estimation method

The value of the flow of the flushing water is now related to the pump flow by most pump manufacturers:

Check the amount of flushing water

Generally take 0.1% to 1% of the pump flow rate. Take a small value when the pump delivery flow is large and a large value when the flow is small, but the minimum flushing water volume is not less than 1m ³ / h. This regulation applies to pumps with a large flow, such as pump flow Q = 6000m ³ / h, calculated as 0.1%, and the flushing water volume is 6m ³ / h. For systems running multiple pumps at the same time, the amount of water consumed should not be underestimated When the pump flow rate is small, such as the pump flow rate Q = 10m ³ / h, and the minimum flushing water volume is 1m ³ / h, it will account for 10% of the pump flow rate. After actual field verification, the value of the flushing water amount is too large. Under the condition of reducing the flushing water amount, the pump and the machine seal can operate normally. The heat generated by the mechanical seal is mainly the heat generated by the friction pair motion and the friction of the end face of the static ring The specified amount of flushing water depends on the flow of the pump, so it is larger than the actual flushing water required. It is especially not suitable for situations where the flow is below 200m ³ / h or the flow is above 2000m ³ / h.

The amount of flushing water can also be checked according to the figure on the right. The flushing water outlet temperature does not exceed 30 ° C.

Table one flushing water

As the seal shaft diameter increases and the medium pressure increases, the pump shaft speed increases, the medium temperature increases, and the amount of flushing water required increases, and vice versa.

Most of the medium conveyed by the slurry pump or desulfurization pump is lower than 70 ° C. As can be seen from the figure on the right, when the medium temperature is lower than 80 "C, the cooling water volume of the machine seal is only related to the seal shaft diameter. The flushing water volume of the pulp pump or desulfurization pump is shown in Table 1. ^[1]

Theoretical calculation of flushing water

Generally, in actual applications, the heat generated on the sealing surface is the main source of heat in the sealing cavity. On the premise of ignoring some heat, the following methods can be used to calculate the heat generated between the two sealing surfaces in frictional motion. Friction power of mechanical seal face

In the formula: P _f end face friction power, the unit is W;

fFriction factor of seal end face. For ordinary mechanical seal, f = 0.1 can be used for estimation;

p _c specific pressure of end face, unit is MPa;

v = average linear velocity of the sealing end face, the unit is m / s;

A = Seal face area. The unit is mm ² .

This power is all converted into thermal energy

In the formula: P _f thermal energy, the unit is J;

m _h flow, unit is L / min;

C _{ph specific} heat capacity, specific heat capacity of water;

t ₂ the outlet temperature of the flushing water, the unit is K;

t ₁ The temperature of the inlet of the flushing water, the unit is K. ^[1]

Flush Water Practice Accounting

(1) Because the temperature rise of the sealing surface is greater than the temperature rise of the sealed cavity, considering the heat of stirring and other uncertain factors in actual use, the amount of cooling and flushing water in actual application is more than 3 times the theoretical calculation value.

(2) When the medium temperature is lower than 80 , the flushing water volume of the machine seal is based on the data in Table 1.

(3) Considering all aspects of the site, the minimum water requirement for sealing water for mechanical seals can be adjusted appropriately according to the actual situation. If the mechanical seal is used in a bad environment, increase the amount of cooling and flushing water to ensure the normal operation of the mechanical seal. ^[1]