Optimization of Operation Mode of ACS4000 Air Compressor System Zheng Peihui (Fujian Nanzhi Paper Co., Ltd., Nanping 353000, Fujian) The paper 5 air compressor needs to maintain the compressed air pressure between 0.68 and 0.75 MPa due to the production process requirements. In the past, the six air compressors of the Nanzhi 5 paper machine were all in the local sequence control mode. Usually six air compressors were running, at least two of them were in the loading state and four were in the idle unloading state. This consumes a large amount of idling power and reduces the service life of the equipment, which brings great difficulties to everyone. The introduction of the Ingersoll Rand ACS4000 air compressor centralized monitoring system solves the above technical problems.
1 The centralized monitoring system's structural system mainly includes: upper computer and centralized control cabinet. As shown in the figure, the upper management computer is added, and the central controller and the upper computer are effectively linked to perform parameter exchange and realize the operation control. The system realizes real-time online detection parameters, acceleration/unloading, sequence start shutdown, fault alarm and other functions under operating conditions. The operating parameters are displayed and stored with a good screen interface, which successfully guarantees the normal supply of gas in the production workshop.
The control programs of the system are all integrated in the PLC of the centralized control cabinet (the hardware composition of the centralized control cabinet is shown in Table 1). The failure of the upper computer during normal operation will not have any impact on the stable operation of the system. The control strategy of the system mainly includes three parts: pressure control, sequential timing rotation, and fault linkage.
1.1 Pressure Control Before the system is linked to operate, the user needs to set the appropriate upper and lower pressure values ​​on the upper computer, and the system pressure will be controlled within the range set by the user. The system pressure is selected as the parent pipe outlet gas pressure of the last gas tank.
1.2 Order Timing The so-called order refers to the start and stop priority assigned to each air compressor in the air compressor unit when defining the control strategy. The so-called timed rotation means that the running sequence will automatically switch to another sequence after the set time, thus balancing the running time of the unit, which is conducive to maintenance and prolonging the service life of the unit. For the order rotation time, the order can be selected from the upper computer and downloaded to the main control PLC.
1.3 Fault chain fault machine will automatically stop, and there will be sound and light alarm on the control cabinet, and the alarm information will also be displayed on the host computer. Taking into account the characteristics of continuous air supply, the failure of the cold dryer does not close the corresponding air compressor.
Table 1 Schneider Premium hardware components Order No. Remarks Order No. Remarks CPU, dual-slot isolated interface converter 2 Host computer operation and function On the computer WinXP interface you can download the control program, you can carry on the air compressor on the host computer Remote operation and modification of related parameters (such as opening machine, whether to participate in linkage operation, adjustment of pressure belt, master-sequence machine setting, running time setting, running number setting, automatic/manual switching, etc.); you can vividly The interface obtains the operation monitoring of the equipment under the online state; the trend curve of important parameters such as pressure and temperature can be obtained through the interface at any time, and the relevant important data is recorded in the database; the diachronic alarm signal can be viewed at any time to facilitate the maintenance personnel. Look for faults.
3 Add/Unload Control Mode In the centralized monitoring system, each air compressor is set to host, backup 1, backup 2, backup 3, backup 4, and standby 5. When it is necessary to reset the air compressor main and standby In the order, please click the ''Empty' button), then clear all the master and backup settings, then click on each air compressor master and backup button, do not point two main and standby buttons on a single air compressor at the same time.
3.1 When there is a load request (1) Case 1: The host is not loaded, then it is loaded first. After the set load time, if there is still a load request, the backup 1 is loaded.
(2) Case 2: When the host is loaded, the system checks whether the standby 1 is loaded. If it is not loaded, the standby 1 starts loading. Cycle through them until the standby 5 is also loaded.
3.2 When there is an unloading request, the standby device 5 is first uninstalled. After the set uninstallation time, the standby device 4 is unloaded until the standby device 1. When the system is in the normal running state, that is, without the paper break signal, the host remains in the loaded state.
4 The actual operation mode of the air compressor The paper machine does not exceed 100m3/min when the paper is cut without paper. The air volume of each air compressor is 40m3/min, so that there is no broken paper. When only 2~3 air compressors are running and idling, the rest of the machines are in the standby state. When the paper machine breaks the paper, the dryer, calendering and coiling paper blowing device are put into use. At this time, the gas consumption is as large as 230m3/min, so it is necessary to simultaneously load the 6 machines at the same time to achieve Production of fast gas requirements. Shown is the control program flow.
4.1 Normal sequence control mode without break signal At this time, the ''system pressure value kPa* of the tank outlet' is adjusted by the 'normal pressure zone'. The system pressure value is taken to the last parent pipe outlet pressure value in the tank. Control system The compressed air main pipe pressure will be continuously detected, the number of air compressors put into operation will be automatically controlled according to the pressure change, the control program flow chart and the corresponding standby air compressor start/stop and add/unload.
(1) When the system pressure is lower than the lower limit of the normal pressure zone, the system will issue a load request. At this time, according to the active/standby sequence, an air compressor is started. If the air compressor to be started is in the stop state, then Start the air compressor first, wait 15s (Y~A start time), the air compressor is loaded.
(2) When the system pressure is higher than the high limit of the normal pressure zone, the system will issue an unloading request, and then uninstall in the active/standby order.
4.2 Control method when there is a paper break signal When the central controller detects the paper break signal, the system will automatically modify the normal/loading pressure band of the six air compressors, and immediately give each air compressor a Load instructions to ensure fast qi. At this time, the "system pressure value kPa*" of the tank outlet is "adjusted", and the normal sequence control mode is immediately invalidated. The system controls the air supply according to the user's preset paper break pressure belt to meet the special requirements of the user. When the paper machine is not broken, the normal sequence control mode is automatically restored.
4.3 Air compressor shutdown control mode When the air compressor fails, we need to stop the maintenance, we can set the air compressor to the "overhaul" state on the host computer, and do not participate in the system linkage operation control (that is, the normal sequence control mode And the control mode of the paper break state), the emergency stop button can also be pressed at the site, the air compressor will be automatically skipped when the system detects, and the linkage operation control is not involved, so as to ensure that the other machines can be controlled in sequence. . At this time, the air compressor cannot be manually operated on the on-site panel, and the machine will not be suddenly activated to ensure the safety of the person and equipment.
4.4Local Local Control Mode When the air compressor is set to Local mode, it means that the air compressor is not in the maintenance state. At this time, the operator can manually start, load, unload and stop. In the Local mode and the unchecked state, after the system restores the Host's set time from Local, the system automatically restores the local state of the air compressor to the Host state linkage.
5 After the actual operation effect centralized monitoring system is used, there is no local order control mode. When the paper is broken, the interval between each air compressor is longer, and the air supply cannot be quickly calibrated. The gas supply often cannot meet the production demand. Nowadays, the system is stable and can meet the special gas supply requirements of the papermaking workshop, and it also contributes a lot to the power saving.
When the system is not put into use, 6 air compressors are added/unloaded, at least 2 of which are in the loading state and 4 of which are in the idle unloading state, and the energy consumed by each air compressor during the idle unloading is *h. The paper machine usually takes a short time to break the paper. After the system is put into use, there are often three air compressors in the standby state. Taking the ideal paper state as an example, the energy consumed by the three air compressors in one year is :(3x110x24x365)=2890800 kWh, nowadays it is calculated at an average of 0.4 yuan per kWh, saving 1.15 million yuan per year for the enterprise, and the total investment of the Ingersoll Rand ACS4000 air compressor station centralized monitoring system is 180,000 yuan. Renminbi, which means that the cost can be recovered two months after the system is put into use. This kind of economic benefit is not only enhances the competitiveness of enterprises in the market, but also has great significance for our country with lack of energy.
6 Conclusion After the centralized monitoring system is put into use, although it can meet the needs of production gas supply, but because the loading and unloading operations are frequently alternated, the order of starting the standby machine is also more frequent, which makes the pressure and current fluctuation of the air compressor are very large. The impact of the piston and the power supply on the cabinet will affect the service life of the air compressor itself. Therefore, if the economy is willing to do so, the air compressor system can introduce AC variable frequency control technology to achieve stepless speed regulation of the air compressor. This has great benefits in reducing noise, improving the surrounding environment, and extending the life of the air compressor.
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