Planning of Power Supply System and Electrical Equipment Configuration in Chemical Enterprises

Technical product version Planning of power supply system and electrical equipment configuration in chemical companies Anwei Yi/./ Next to the mother 1 out of 2 out of 3 out of N Chemical production continuity and toxic, hazardous, flammable, explosive and other characteristics determine its power supply The importance of It is known to classify chemical power as Class A load in the power system. How to arrange our power system within a chemical company so that it can achieve maximum safety and reliability and economy is the main content discussed in this article.

1 Arrangement of one-time line-in system Arrangement of one-into-two 2 main transformers Depending on the layout of the incoming line, we can select multiple master transformers on our double busbars. The purpose of doing so has the following aspects: Long-term engaged in corporate electrical management.

(Tianjin Soda Plant, Tianjin 300450) At present, the vast majority of chemical companies use dual power supply lines, inner bridges or outer bridges. This arrangement has many advantages, the most prominent being less investment and flexible methods. However, there are great restrictions on the number of main transformers, which is not only detrimental to the economic operation of the company (as will be explained later), but also limits the maintenance methods and the future development of the company. It is recommended to use a double bus configuration. If possible, dual buses with bypass buses are preferred. As shown. 2.1 Minimize operating costs.

We know that there are capacity charges for electricity tariffs. At a transformer load of 80%, the capacity charge accounts for about 10% of the total electricity charge. We reduced the capacity of the main transformer to reduce the operating cost of the transformer, and also reduced the cost of spare capacity (can be prepared for N 1). 2.2 Increased reliability. The overall power supply reliability of the enterprise has been improved. Since the load of a single transformer is small, the loss caused by the failure of one main transformer is correspondingly small.

2.3 Improve the completion rate of large, medium and minor repairs of the main transformer. Since N can be prepared for 1, each main transformer has sufficient repair time.

2.4 The maintenance is convenient, and the equipment (knife switches, switches, transformers) of the primary system can be arranged for maintenance without affecting the power supply.

2.5 The development of the enterprise is not limited by the capacity of the main transformer.

2.6 Increased utilization of the main transformer. The larger the company's electricity load, the more independent the chemical production system, the stronger the superiority of this configuration. When N is greater than 4, the superiority will be clearly apparent. According to the above objectives, we should follow the following principles when selecting the capacity of the main transformer: A single system (branch) must be independently zoned. That is, when a main transformer fails, it can only affect the production of one system (branch), and cannot affect the entire chemical production. In the key branches of the production that affect the entire chemical system, it may be considered to install a self-injection device on the secondary side of the main transformer.

The capacity should be considered in the same way to prepare for each other.

When wiring the power distribution room, sufficient outlet intervals should be reserved and sufficient control intervals should be reserved in the control room.

The capacity should not be too large, generally considering the company's overall power load of 25% ~ 35% is appropriate.

When the pressure device reaches 2 or more, 2 devices can be considered. 1. When N devices are reached in the future, one standby device can still be reserved. 3 The configuration of the secondary bus of the main transformer In the chemical industry, there are more medium-voltage motors (6 kV). The 6 kV buses of most companies are single-bus segmented. According to the principle of the incoming line arrangement and the main transformer configuration described in this paper, it is obvious that the arrangement of single bus bar segments is not suitable. It is recommended to use a single bus with the bypass bus arrangement.

As shown.

It should be noted that the main considerations of this type of connection for low-voltage transformers are as follows: (1) To provide necessary lighting power and to inspect the power supply when the whole plant is shut down for maintenance. (2) When the 6kV bus is in overhaul or fault, it provides the necessary lighting and process power for the craft workshop. For larger companies in the factory area.

5 Control, measurement and configuration of relay protection 5.1 There are no problems with the loop of the control loop. This article does not repeat them. For the control circuit of the 6kV motor, according to our operating experience, when the distance between the motor and the power distribution room (control cable length) is 300-400m, the control operation is no problem. When the distance between the motor and the power distribution room exceeds 500m, it is recommended to add a 6kV secondary power distribution room on the motor.

5.2 Measurement loop When the distance between the motor and the power distribution room exceeds 100m, in order to reduce the secondary burden of the CT at the motor control cabinet of the distribution room and improve the measurement accuracy, it is recommended to add CT on-site measurement at the motor. 5.3 Relay Protection Configuration The current microcomputer protection is a mature technology and it is recommended to adopt such technologies. However, special attention should be paid to the fact that the selected microcomputer protection manufacturers must be unified, otherwise it will cause great trouble for our production management and telemetry work.

4 Summary 4.1 The advantages of the main line-out configuration of this line entry: flexible operation mode, convenient overhaul, low operating cost, high overall reliability, and large room for enterprise development. However, there are also obvious shortcomings: Due to the large size of the power distribution equipment, the area is large, and the cost of the civil works invested once is high.

4.2 If the transformer secondary meters use 6kV outlet line, the whole plant only needs to be on-duty personnel in the total landing substation, while other 6kV distribution rooms do not need to be on-duty personnel. This can also greatly reduce the company's electrical operating personnel, but it also greatly increases the total drop station 6kV cable feed.

4.3 If the transformer secondary uses 35kV outgoing line (incoming line voltage is above 110kV), although it can reduce the output of 6kV cable, several 35kV substations are required. If a 35kV substation does not have on-duty personnel, a series of remote control and telemetry devices are also required. This configuration is suitable for the configuration of 6 low voltage (380V) devices. As mentioned earlier in the 380V bus, single busbars can be used instead of complex busbars. However, it is very necessary to install some devices for larger capacity motors or more important motors.

6.1 Anti-wrenching devices should be installed at the important motor to prevent the motor from being cut off when the voltage fluctuates (important motor refers to the motor that is very important in process production).

6.2 In the motor or water pump that requires speed regulation, the frequency converter shall be installed in the fan to facilitate the speed regulation and energy saving in the future production.

6.3 The soft starting device should be installed at the large-capacity motor to facilitate the improvement of power supply quality and prolong the service life of the motor and mechanical parts. (In the power supply network with large system capacity, 8% to 10% of the motor capacity of the power transformer is achieved. Can be considered to be a larger capacity motor. The proportion of the area where the system capacity is small should be adjusted downwards.

6.4 For motors that are extremely important, such as personal safety and public safety, they should be equipped with >Industry news. Manufacturing success. Nanjing Yangzi Petrochemical Company's chemical plant The original 6 650M2 large heat exchangers HE-302 were imported from foreign machines. Its frequent leakage has brought great impact on the circulating water system and has become a “killer” that restricts the production of chemical plants. For this reason, the plant had imported one and the same type of heat exchanger from Germany and Italy, respectively, to be replaced, but the difficulty has not yet been solved.

Through deep investigation and research, the leakage of the heat exchanger is caused by the unreasonable original design caused by vibration of the tube bundle, resulting in long-term fatigue of the tube bundle resulting in fracture. In this regard, the plant cooperated with the design institute of Yangzi Company to redesign and modify the structure of the heat exchanger, strictly control the material selection, and ensure the manufacturing quality of the heat exchanger. In May 2000, China's first large-scale heat exchanger with a heat-exchange area of ​​650 M2 was officially installed and put into operation. All technical performance indicators were better than those of imported DC motors or UPS.

Special attention should be paid to: When selecting frequency conversion equipment and soft-start equipment, it is necessary to select devices with current protection, overheat protection, voltage protection, and anti-voltage fluctuation. Since the frequency conversion device and the soft start device are all thyristor devices, any type of self-injection device has no meaning to it.

7 DC System Configuration The importance of the DC system as the last security power source in the power distribution system is obvious. Often we are considering the battery capacity, and only the designed value of the DC power distribution device. In June 2001, the second 650M2 heat exchanger optimized on the basis of the first heat exchanger was also installed and used to fill the gap in the development of large-scale heat exchangers in China and ensured the long-term stable operation of the PTA plant. , can save 1.4 million US dollars. The plant is preparing to gradually replace the other four heat exchangers. At present, the HE-302 650M2 large heat exchanger has passed the technical appraisal of Sinopec Group Corporation.

(Wang Zhenhai) Corrosion and Treatment of the Inner Wall of the Jacket The ammonia plant of the First Chemical Fertilizer Plant of Sichuan Chemical Industry Group Co., Ltd. has been operating since the start of production. During the process of operation, water jackets in various locations have been found to emit a certain amount of “red water”. After sampling and analysis, the pH of the drained water was only 5.1, and the conductivity was as high as 62 (xs/cm, p. This indicates that a large amount of corrosive substances such as iron ions were generated, which seriously affected the stable operation of the production equipment and considered the needs of the power system. This ignores the need for process systems and instrumentation systems, which not only results in a waste of duplicate investment, but also does not guarantee the security of small-capacity DC systems.It is recommended to build two (even larger) batteries at the total drop station. The group is sent to a number of local areas within the plant through DC feeders. A UPS unit with corresponding capacity is set up outside the local area. The UPS unit supplies the instrument control, and important motor and plant lighting.

In terms of power allocation, it should be the benevolent who sees wise men. The comments I have made are for the sole purpose of my peers and I welcome my colleagues' opinions and opinions. Service life.

After repeated analysis and analysis, the possibility of infiltration of the process medium was eliminated, and it was determined that the water quality was acidic.

In order to eliminate the acid corrosion of the water jacket and prolong the service life of the equipment, it was decided to increase the PH value of the influent to make it alkaline. Because the water jacket is mainly used process condensate, in order to save money and reduce process costs, the plant uses a standby ammonia pump for ammonia pump, and the other with a 1/2 pipe, direct dilute ammonia water to water jacket water supply manifold . In order to facilitate the control of the water supply index, an on-line PH meter is set up on the water supply mains to continuously monitor the pH value of the feed water to ensure that the feed water is weakly alkaline (pH is about 8.5). The entire investment cost is very low, just buy an online PH meter.

The corrosion of equipment has been greatly reduced, the safety of equipment of several tens of millions of yuan has been protected, and it has contributed to the improvement of domestically-manufactured equipment. It has certain advancement and economic benefits.