Complete set of AC/DC electric desalting & dehydration equipment

Description：

The complete set of AC/DC desalting and dehydration equipment is an electric desalting technology jointly developed by our company and Sinopec Luoyang Petrochemical Engineering Company. The technology adopts a single-phase half wave rectifier DC power supply equipment integrating step-up and rectification to transmit positive and negative DC power to the positive and negative plates in the electric desalting vessel. In the electric desalting vessel, the positive and negative electrodes alternate from left to right along the axis, and variable pole spacing mesh electrode plates are suspended. By changing the electrode plate structure and electrode distance, the DC weak electric field, DC medium electric field and DC strong electric field can be obtained. The strong DC electric field has network structure, which has a uniform electric field distribution, which is convenient for small water droplets to reach the electrode plate and coalesce to improve the desalting and dehydration rate.

Advantages：

AC/DC desalting equipment adopts single-phase half wave rectification power supply equipment. The DC voltage on the positive and negative plates is half sine waveform, but due to the capacitance between the plates, the potential on the plates will continue to discharge when it reaches the peak. Voltage waveform on positive and negative plates. Due to the alternating voltage on the positive and negative plates, an alternating electric field is formed between the end plate at the lower end of the plate and the oil-water interface, which can prevent corrosion caused by a single DC electric field. Its electric field strength is generally designed as a weak electric field, which can make some water droplets of larger particles in the emulsion coalesce and remove in the electric field. After removing large water droplets, the emulsion moves upward and passes through DC weak electric field, DC medium electric field and DC strong electric field in turn. When the emulsion passes through the DC electric field, the salt water droplets in the emulsion also produce dipolarity under the action of the electric field force, and the adjacent water droplets also attract each other and coalesce. Due to the vertical arrangement of the electrode plates, the position of the water droplets that produce even polarization in the DC electric field is unbalanced, and the water droplets move towards the positive and negative plates under the action of the electric field force, that is, a horizontal "electric pulse" phenomenon is produced. The sedimentation of emulsion and water droplets moves upward and downward, which greatly increases the probability of collision and coalescence of water droplets compared with AC electric field. After passing DC weak electric field and medium electric field, most salt containing droplets in the emulsifier have been removed, leaving only smaller salt containing droplets. Because the  DC strong electric field formed by our company's electrode plate is a network structure, all small water droplets gather on the electrode plate, or after reaching the electrode plate to obtain charge, they accelerate to the electrode plate with opposite polarity, collide and coalesce with water droplets, which is the reason why the desalting and dehydration effect of our company's technology is higher than that of other technologies.

In addition, the positive and negative plates in the DC power supply circuit are half wave voltage, and the circuit is not directly formed between the two plates. The DC voltage on each group of electrodes is only 45% of the AC voltage. There is conductive current between the plates only during the discharge process, which greatly reduces the power loss, which is only half of the normal full wave rectification form. However, there is a certain capacitance between the electrode plates, and the decline of the positive and negative electrode plates actually has a delay phenomenon. Therefore, there is an electric field between the electric plates. This is also the essential reason why AC/DC desalting equipment saves more power than AC desalting equipment.

5 million tons / year complete set of AC/DC electric desalting equipment for PetroChina North China Petrochemical Company