In order to meet the requirements of flexibility of production and operation, calculation and selection, as well as actual production, chemical enterprises design. Many industrial pumps are in the condition of "big horse pulling car" due to the change of raw material property and product scheme adjustment, which results in the waste of electric energy. 80% of the electricity consumption of petrochemical enterprises is used in the driving of industrial pumps. The key to reduce the cost is to save energy and reduce the consumption of industrial pumps.

In order to meet the requirements of production flexibility, change of raw material properties and adjustment of product scheme, most of the industrial pumps in petrochemical enterprises are in the working condition of "big horse pulling small car", resulting in waste of electric energy. Based on the analysis of the energy-saving technology and its implementation effect of various pumps, this paper expounds the implementation method, energy-saving effect, advantages and disadvantages of the excess head control technology and frequency conversion speed regulation technology of pumps in the petroleum industry.

Excess head control technology of delivery pump

1. Cut the outer diameter of impeller

When the flow or lift exceeds 3% - 5% of the required amount, the outer diameter of the impeller can be cut to reduce its flow, lift and power (the characteristic curve moves down). Within a certain cutting limit, it can be considered that the installation angle of the blade out of El is constant and the flow is similar, and the performance parameters after cutting can be converted according to the similar principle.

2. Outlet throttling

The most commonly used and simple regulation method is to increase the loss of pipeline system and reduce the flow when the outlet valve is closed, but the head loss is large and the power reduction is little, which is not suitable for the pump with too large flow regulation requirements, especially for the pump with steep drop head performance curve, which is even less economical. Generally, the opening of the valve should not be less than 50%, otherwise, the pump is too large.

3. Bypass regulation

The outlet pipeline of the pump is provided with a bypass to return part of the liquid to the inlet or suction tank of the pump. The operating point of the pump changes to the aspects of large flow and low lift, i.e. the actual pumping capacity is larger than the required capacity, which will not cause liquid overheating, cavitation and vibration due to the flow rate lower than the minimum continuous flow. But increase the power consumption, and the liquid return to the pump inlet, so that the liquid temperature has increased, generally not suitable for centrifugal pump to regulate the flow, the most suitable for the vortex pump, because the power of the vortex pump decreases when the flow increases.

4. Inlet throttling

The head loss of inlet throttling is less than that of outlet throttling, but it may cause cavitation and evacuation. For multi-stage pumps, the axial force may even change suddenly and damage the components, so it is generally not used. However, for 121 places of the second pump in series operation, due to the large margin of suction pressure, it can be used.