Sunwoele high-voltage VFD (Variable-frequency Drive) energy-saving retrofit plan

1.Project background

Hainan Cracking 1# has two fans, respectively 400kw (pilot)/314kw (drum) -6kv. The drive motors of these fans are designed according to the maximum rated load, but the fans can operate at the maximum rated load for very little time in a year. Among them, the two fans in unit 1 # operate at 60% of the time throughout the year. on the load segment.

Due to the influence of design and manufacturing technical conditions, the output power of the main electrical equipment of the power plant such as blowers, induced draft fans, water supply pumps and other high-energy-consuming equipment cannot change with changes in the group load. In order to meet the load's requirements for changing air volume, we Traditional technology has always used the method of adjusting the opening of the air duct baffle. This method can change and adjust the air volume, but cannot adjust the speed of the drive motor and save energy proportionally, resulting in a large waste of energy in industrial production and an increase in production costs. A large part of the energy is consumed in throttling losses. Therefore, technological transformation of existing equipment will undoubtedly promote technological progress in the cracking industry, reduce costs, and improve the overall competitiveness of Chinese petroleum companies.

2. Overview of site conditions and modification requirements

2.1 Overview of site conditions

4#’s existing blower motor parameters are as follows:

Fan name Motor model Rated voltage Rated current Rated power Power factor Rated revolutions

Induced draft fan YB450M2-6W 6kV 48.7A 400kW 0.85 990 r/m

Blower YB450S3-6W 6kV 38.3A 315kW 0.85 990 r/m

In order to reduce production costs, reduce energy consumption, and adapt to China's "Tenth Five-Year Plan" requirements for energy conservation and comprehensive utilization of resources, adopt the economic growth model of low consumption, low emissions, and high-efficiency sustainable development concepts, and apply frequency conversion energy-saving technology to transform Technical shortcomings of traditional crafts. Our unit applied to put the work of tapping the potential of energy saving and reducing consumption on the agenda, starting with technological transformation, and seeking ways and means to save energy and reduce consumption.

In view of the above phenomenon of energy waste, the use of high-voltage variable frequency speed regulation technology to carry out technical transformation of the driving power supply of electrical equipment in the cracking field is an effective way for our unit to save energy, reduce consumption and improve the competitiveness of bidding on the Internet.

2.2 Transformation requirements

1. Process requirements: According to the load demand, stepless continuous speed regulation of 0 ~ 50Hz is achieved.

2. Control mode requirements: remote control and local manual control.

3. Advanced requirements: The system design should be able to meet the various data transmission, online monitoring and data processing functions required by future digital oil fields;

4. Reliability requirements: On the premise of high reliability of the system itself, VFD (Variable-frequency Drive) bypass automatic switching and manual automatic switching should be added;

5. Adaptability requirements: The system design should be able to meet the fluctuations in air volume caused by changes in oil production in the next 3-5 years, that is, the system's adjustment margin for air volume must be large enough.

6. Energy saving requirements: It is required that the total investment recovery period of the renovation shall not exceed three years.

7. Safety requirements: The system has various electrical protection functions and meets on-site anti-corrosion and other requirements;

8. Environmental protection requirements: Meet the common standards for harmonic pollution of power grids in China and abroad.

3. Implemented transformation plan

3.1 VFD (Variable-frequency Drive) selection plan

Since the specific plan implemented for high-voltage frequency conversion transformation is directly related to the selection of VFD (Variable-frequency Drive), our company first conducted a selection inspection of VFD (Variable-frequency Drive). After careful and careful comparison, finally Italian Senno product - high-voltage VFD (Variable-frequency Drive) has won our recognition for its excellent quality, complete technical performance and thoughtful after-sales service.

3.2 Main loop plan

Based on the importance of the fan load in our company, we decided to adopt a one-to-one variable frequency control scheme, which is a VFD (Variable-frequency Drive) with a fan motor. In order to increase the reliability and safety of operation, a power frequency bypass circuit is added. The specific design plan is shown in Figure 1:

Figure 1: Primary main circuit wiring diagram

Figure 2: Structural diagram of high-voltage variable frequency speed regulation system

QF is the user's vacuum circuit breaker, and QS1, QS2, and QS3 are three high-voltage isolation knife switches. Between QS1 and QS2 is the high-voltage VFD (Variable-frequency Drive), and QS3 is the bypass knife switch. When the motor needs to run with variable frequency, QS3 should be opened first, then the QS1 and QS2 knife switches should be closed, and finally the vacuum circuit breaker QF should be closed to energize the VFD (Variable-frequency Drive) and start the VFD (Variable-frequency Drive) to drive motor. When the motor needs to run at power frequency, the QS1 and QS2 knife switches should be opened, the QS3 bypass knife switch should be closed, and finally the vacuum circuit breaker QF should be closed to directly drive the motor to run at power frequency. This operating mode is a backup operating mode that uses power frequency to ensure equipment operation under special circumstances such as VFD (Variable-frequency Drive) failure or maintenance.

The above scheme is a typical manual bypass scheme, which requires that QS2 and QS3 cannot be closed at the same time, and safety interlocking is achieved mechanically.

In order to protect the faulty VFD (Variable-frequency Drive), a trip command is issued when the VFD (Variable-frequency Drive) fails, and the on-site