Summary:To quantify the energy consumption of spinning mills, we took the 115,200 spindles集聚spinning production line as an example, detailing the process flow and equipment configuration. We compiled the total installed power of main and auxiliary machines, air conditioning, dust removal, refrigeration, and lighting equipment across various processes. We conducted tests on the actual total power during production and analyzed the rated power and measured power occupancy of various equipment, identifying the causes of inefficient energy consumption and proposing energy-saving technology transformation projects. We proposed a series of measures, including using variable-frequency control for air conditioning fans, employing a constant pressure variable flow system for dust removal and precision combing systems, correlated control for cotton blowing fans of the spinning frame with a single fixed monitoring system, optimizing the frequency of the集聚spinning vacuum fans, and peak shaving electricity usage, among others. By implementing these comprehensive energy-saving measures, the mill is expected to save 3.194 million kW?h of electricity annually, achieving a 5.7% comprehensive energy-saving target.
Keywords:Textile mill; Energy consumption; Quantitative analysis; Main and auxiliary machinery; Air conditioning and dust removal; Rated power; Measured power
0. Introduction
Modern textile factories are continually advancing towards large-scale production, equipment automation, and high-speed operation. The installed power per 10,000 spindles exceeds 1,100kW, characterized by continuous operation and high load factor. The installed power of air compressors, air conditioning dust removal, and cotton picking equipment is high, leading to significant electrical load and increased actual energy consumption. During the operation and management process, analyzing and statistically reviewing the installed power and actual energy consumption of each process equipment identifies areas with potential for energy-saving improvements. Implementing mature energy-saving technologies and effective management measures reduces unnecessary energy consumption, which is an effective approach to energy conservation and efficiency improvement. This study, based on the specific conditions of a newly constructed modern 115,200 spindles集聚纺纱 production line, clarifies the installed power and actual power ratio of the air conditioning and dust removal equipment in the spinning workshop through statistics of main and auxiliary machinery installed power, actual energy consumption testing, and energy use analysis. It identifies areas for energy-saving operation management and discusses several effective energy-saving measures.
Analysis of Energy Consumption on Spinning Production Line
The energy consumption in spinning workshops primarily includes main machine production, auxiliary air conditioning and dust removal, air compression and refrigeration, and lighting. The specific energy consumption varies depending on the main machine equipment in the workshop. For analysis, let's take a 115,200 spindles集聚spinning production line as an example.
1.1 Process Flow and Equipment Configuration
The spinning production line is designed with a capacity of 115,200 spindles, featuring a new domestic machine as the main unit. It primarily produces medium and fine-count combed cotton yarn. The process flow and equipment configuration are as follows.
JWF1012 reciprocating cotton picking machine (3 units) → FA103B twin-axial flow opener (3 units) → JWF1102 single-axial flow opener (3 units) → JWF1026-160-10 multi-bin blending machine (4 units) → JWF1124C-160 single roller carding machine (4 units) → JWF016 fiber separator (4 units) → JWF1054 dust removal machine (4 units) → JWF1204B carding machine (50 units) → JWF1313 doubling machine (12 units) → JWF1383 doubling and winding machine (6 units) → JWF1278 comber (35 units) → JWF1312B doubling machine (12 units) → JWF1458A roving frame (18 units) → JWF1566JM spinning frame 1200 spindles (96 units) → VCRO-E automatic winding machine 72 spindles (26 units).
The auxiliary equipment includes 9 sets of dust removal systems for cleaning and combing, 4 sets of precision carding cotton picking systems, 4 sets of pre-spinning air conditioning systems, 8 sets of fine yarn air conditioning systems, and 2 sets of winding air conditioning systems. There are 3 air compressors, with two in use and one in reserve, designed for a gas supply volume of 64.4 Nm3/min and a pressure of 0.85 MPa. The workshop covers an area of 40,986 m2. The main workshop is constructed with a light steel gate-shaped structure, while the auxiliary buildings are framed with reinforced concrete. The factory is located in a certain area of Henan Province.
1.2 Main and auxiliary machine installation power
According to the equipment nameplate, the installed power of the equipment is counted, and the total installed power of the main and auxiliary equipment by process is shown in Table 1.
Table 1: Overview of Main and Auxiliary Machine Equipment Installation Power by Process
Figure 1 reveals that with the inclusion of refrigeration equipment, the total installed power is 13,550.6kW, with the power distribution as follows: main unit 73.2%, air conditioning 14.0%, dust removal 4.2%, air compressor 2.1%, refrigeration 5.0%, lighting 1.5%. Due to the continuous increase in the level of automation of textile equipment in recent years, the installed power of the cleaning and carding process has significantly improved. Calculating by main and auxiliary machines, the main equipment in the workshop accounts for 73.2% of the installed power, air conditioning equipment accounts for 14%, dust removal equipment accounts for 4.2%, and air compressor-refrigeration equipment accounts for 7.1%. By process, the cleaning and carding process accounts for 11%, the fine and thickening process accounts for 12.7%, the spinning process accounts for 58.7%, and the winding process accounts for 10.1%. Since refrigeration equipment operates during the peak summer months, by classifying equipment based on year-round operation, the main equipment accounts for 77% of the installed power, air conditioning and dust removal account for 18.2%, and apart from the main equipment, air conditioning and dust removal are major energy consumers.
1.3 Actual Energy Consumption of Main and Auxiliary Machines
Based on the specific characteristics of equipment across various spinning processes, there are differences in the safety factor and load factor of the equipment's power rating, leading to a significant disparity between the installed power of the equipment and its actual energy consumption. The measured electricity usage of individual equipment during operation truly reflects the actual energy consumption of the equipment. Taking the normal full-load production of fine denier spun yarn in the workshop as a basis, from January to June 2020, we conducted actual measurements and statistics of the total electricity usage in the workshop and the electricity usage of the air conditioning and dust removal system, as shown in Table 2.
Table 2: Total Electricity Consumption and Air Conditioning Dust Removal Electricity Consumption in Workshop
From Table 2's electricity consumption statistics, it is evident that without the refrigeration unit, the main engine's installed power is high, resulting in a lower load factor compared to air conditioning and dust removal equipment. The actual power consumption of the main engine does not match the installed power ratio. The air conditioning system utilizes automatic temperature and humidity control technology. The electricity consumption of the workshop air conditioning system still accounts for 13% to 13.9% of the total workshop electricity consumption during normal months, slightly less than the installed power ratio of 14.7%. The dust removal system, operating at industrial frequency, consumes 6.5% to 6.9% of the total workshop electricity, which is greater than the installed power ratio of 4.4%. Without refrigeration, the air conditioning and dust removal electricity consumption takes up 18.5% to 20.7% of the total workshop electricity consumption, indicating that the electricity consumption of the air conditioning and dust removal system is significant and should not be overlooked, making it an essential part of energy-saving operation management.
To further analyze the energy consumption of dust removal equipment and the main service unit, power ratings of the cleaning, carding, and fine combing main equipment, as well as the power ratings of the auxiliary dust removal equipment, were statistically compiled. Under the condition of all main equipment in the workshop being fully operational and the dust filtration equipment running normally, the corresponding actual power consumption was measured, as shown in Table 3.
Table 3: Comparison of Installation and Actual Power Consumption of the Pre-spinning Main Unit and its Dust Filtration Equipment
From Table 3, it is evident that the installation power of the main equipment is higher than that of the dust-filtering equipment. The main equipment's installation power accounts for 61.4% to 70.8%, while the auxiliary dust-filtering equipment's power occupies 29.3% to 38.6%. However, the actual power consumption ratio of the main equipment is only 41.3% to 53.3%, with a load factor of 0.374 to 0.435. Due to the direct operation of the dust-filtering equipment with the designed auxiliary fan parameters, the actual power consumption ratio of the dust-filtering equipment is 46.7% to 58.7%, and the equipment load factor ranges from 0.791 to 0.983. This indicates that the load factor of the dust-filtering equipment is high, with an increased actual power consumption ratio, leading to higher energy consumption, and thus requires energy-saving operation and management.
Major Energy-Saving Measures Research
2.1 Energy-efficient Air Conditioning Systems
Air conditioning system energy consumption is a significant consumer after the main equipment. Since the air conditioning system is designed and matched under the condition of fully operational workshop equipment, high heat generation, and high outdoor temperature and humidity parameters in summer, it is necessary for the system to adjust in real-time with the changes in workshop load. An accurately algorithmic automatic control system for air conditioning is highly beneficial. While ensuring stable workshop temperature, humidity, and air flow, energy-saving adjustments should be a major consideration. Utilizing suitable outdoor fresh air can reduce the operating frequency of fans and pumps, aiming for energy conservation and cost reduction. During the air conditioning adjustment process, the automatic control system uses enthalpy comparison to prioritize fresh air cooling capacity and implement segment-wise accurate energy-saving control measures. In the adjustment of pumps and fans, the sequence of operation should be differentiated; when a speed reduction is needed, the high-power motor should be reduced first, followed by the low-power motor. Conversely, when increasing speed is required, start with the low-power motor and then the high-power motor to save on energy consumption. To analyze the energy consumption of variable frequency fan speed control, taking a 30kW axial flow fan as an example, energy consumption at various frequency segments was measured, with the actual energy consumption detailed in Table 4.
Table 4: Comparison of Measured Energy Consumption at Different Frequencies of the Wind Turbine
Figure 4 indicates that for each 1Hz decrease in frequency, the wind turbine's measured power decreases by 1kW to 1.6kW, adhering to the fundamental rule that wind turbine power is proportional to the cube of the rotational speed. Under low-speed operation during winter, the power consumption can even drop to 50% of the original wind turbine's energy consumption. Although the wind turbine's energy consumption decreases with lower frequency, the operating frequency should not be below 35Hz to avoid significantly reducing the airflow volume and pressure, which would impact the workshop's air flow organization and ventilation. The 35Hz to 45Hz range in Table 4 represents the wind turbine's standard operating frequency, which is between 70% and 90% of the rated frequency, demonstrating significant energy-saving effects.
2.2 Dust Removal System Energy Efficiency
Designers typically base their dust removal and exhaust air volume, as well as pressure parameters, on the manufacturer's specifications for the main equipment. They then appropriately multiply these by a safety factor to determine the air volume and pressure of dust removal equipment and fans. In actual operation, most systems exhibit a higher air volume and pressure than necessary, leading to increased unnecessary energy consumption. As shown in Table 3, the actual energy consumption of dust removal equipment is nearly equal to the actual power consumption of the main equipment, which is an issue that cannot be ignored.
By utilizing a constant-pressure variable-flow control adaptive dust removal system, the operation of dust removal and cotton collection equipment can be adapted to different types and operating conditions through maintaining the negative pressure at the main air intake. This approach can enhance the overall energy efficiency of the dust filtration system. Modification with a constant-pressure variable-flow adaptive control system can reduce the actual power consumption of the main fan in the cleaning and combing dust removal system by over 25% while the main machine is operating normally. Reducing the unnecessary energy consumption of the dust and cotton collection system is an effective method for energy-saving transformation of the dust filtration and cotton collection system.
Additionally, closely manage the start and stop times of auxiliary equipment like dust filters and cotton collectors, ensuring they align with the main equipment in the workshop. This will reduce unnecessary energy consumption of auxiliary equipment and prevent electricity waste. Implement interlock control between main and auxiliary equipment to synchronize their operations, achieving a sequential start and stop through the interlock circuit. This approach minimizes electricity waste caused by premature start-up or delayed shutdown of auxiliary equipment.
For this case, if the dust removal and precision carding cotton collection system is modified to a constant pressure variable flow, based on the actual energy consumption of the dust removal system as shown in Table 3, and calculated with conservative data for a 15% energy saving, this workshop can save 45,000 kW·h of electricity per month, totaling 540,000 kW·h annually.
2.3 Fine Denier Cotton Absorption Blower Energy-Saving Test
Fine Denier Cotton Absorption Fans typically operate at a rated frequency of 50Hz, running at high speed regardless of the number of broken ends. Referring to the energy-saving transformation experience of fine denier cotton absorption fans, by utilizing the main spindle monitoring device and linking it with the cotton absorption fan inverter, the operating frequency of the cotton absorption fan can be controlled based on the number of broken ends to achieve energy-saving and cost reduction. Taking a 1070-spindle 118# fine denier machine as an example, with a cotton absorption fan of 7.5kW, spinning variety JC9.8tex, spindle speed of 20,000r/min, and yarn drop length of 5717m. By linking the single spindle monitoring device to control the cotton absorption fan inverter, the fan's operating frequency is controlled, setting the low-frequency to 35Hz. During normal frequency operation, the reduction in broken ends is 50, with each frequency segment running for 6 hours. The energy consumption test results of the cotton absorption fan under the production conditions of the workshop are shown in Table 5.
Table 5: Energy Consumption Tests of Cotton Absorbing Fan at Different Frequencies
Figure 5 indicates that the actual power consumption is high at 50Hz, reaching 4.84kW. Under the premise of meeting the process requirements, by using the technology of linking the frequency of the exhaust fan to the single-spindle monitoring, and controlling the variable frequency converter of the exhaust fan based on the number of broken ends of the spinning machine, the actual power of the exhaust fan is significantly reduced. Under the condition of maintaining a small negative pressure of 450Pa at the cotton intake port of the flute, after long-term operation tests, the measured power of the exhaust fan is 2.40kW, which is a reduction of 2.44kW compared to the 50Hz operation. Considering factors such as variety, blending of cotton, condition of the cotton intake pipe, and cleaning of the wind box, the low-frequency setting for the exhaust fan is set at 40Hz, and the small negative pressure at the cotton intake port of the flute is set at 600Pa. Tests were conducted on multiple spinning machines of different varieties, and the daily power consumption per machine is shown in Table 6.
Table 6: Energy-saving comparison after linking cotton-picking fans of different varieties with single-spindle monitoring
Figure 6 reveals that by implementing single spool linkage technology in the cotton blowing fan, each spinning frame can achieve an average daily energy saving of 45.25 kW·h, resulting in a total energy saving of 4344 kW·h for the entire workshop. This translates to an annual energy savings of 1.52 million kW·h.
2.4 Energy-saving Test of集聚纺Negative Pressure Fan
Fine yarn cluster spinning vacuum fans operate under high vacuum values, which not only results in higher energy consumption but also leads to long-term full-load operation of electrical equipment, significantly shortening their service life and increasing maintenance workload. Through extensive testing, by adjusting the vacuum value appropriately, the operating frequency of the vacuum fans can be reduced while still meeting production process requirements, achieving the goal of reducing load and consumption. A frequency adjustment test was conducted on 10 cluster spinning vacuum fans of two types to meet production process requirements. The fine yarn machine 301#~305# spun JC11.8tex, and 208#~212# spun JC9.8tex. The specific energy consumption comparison is shown in Table 7.
Table 7: Comparison of Frequency Regulation Tests for Negative Pressure Fans in集聚纺
Figure 7 indicates that by adjusting the frequency of the集聚纺风机, the test machine can achieve an average power reduction of 1.5 kW per unit while meeting normal production requirements. If implemented across the entire workshop, the power reduction could reach 144 kW, resulting in a total annual energy saving of 1,134,000 kWh.
2.5 Peak Electricity Demand Avoidance Through Scientific Scheduling
National Grid power supply generally employs a peak-off-shoulder-valley electricity price ladder, with each period occupying 8 hours. The peak price is 1.5 times the shoulder price, while the valley price is only half. The cleaning and combing section typically has high production capacity, focusing mainly on "ensuring supply." By utilizing the low-price valley and shoulder periods, it increases stockpiling in the preliminary spinning stage, reduces peak operation hours, and saves electricity costs. Taking this workshop as an example, the cleaning and combing unit's actual power is 788.2kW. If the peak and shoulder periods are each reduced by 1.5 hours of operation daily, the daily electricity consumption can be reduced by 1182.3kW?h in the peak and shoulder periods respectively, saving 397,300 yuan in electricity costs annually.
3. Ankeai Building Energy Consumption Analysis System
3.1 Overview
The Acrel-5000web Building Energy Consumption Analysis System is a user-end energy management analysis system. It builds upon the electrical energy management system by adding centralized collection and analysis of water, gas, coal, oil, heat (cooling) energy, etc. By segmenting and statistically analyzing all energy consumption at the user end, it presents the usage and consumption of various types of energy to management or decision-makers through intuitive data and charts, facilitating the identification of high-energy consumption points or inefficient energy consumption habits. This effectively saves energy and provides accurate data support for users to further implement energy-saving renovations or equipment upgrades. Users can carry out energy calculations according to national regulations, analyze the current situation, identify issues, explore energy-saving potential, propose practical measures, and submit energy calculation reports to departments responsible for energy conservation at or above the county level.
3.2 Application Sites
System design, construction, and operational maintenance for energy consumption monitoring and management in various industries such as public buildings, corporate groups, industrial parks, large-scale properties, schools, hospitals, and enterprises.
3.3 System Function
3.3.1 System Overview
Platform operational status, monthly energy consumption calculations, map navigation, hourly and monthly energy consumption curves, and year-on-year comparison of daily and monthly energy consumption are displayed in a rolling manner.
3.3.2 Energy Consumption Overview
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3.3.3 Energy Consumption Statistics
The company has implemented a daily, monthly, and annual reporting system for energy consumption statistics based on building, regional, sub-item, and branch structure. It supports exporting report data to Excel and allows for the generation of bar charts from selected building data.
3.3.4 Reimbursement Rate Statistics
The report on the composite rate provides daily, monthly, and annual statistics of peak, off-peak, flat, and valley electricity consumption and cost for different branches under a single building. It supports data export to Excel.
3.3.5 Year-on-Year Analysis
Energy consumption data for buildings, sub-items, regions, and branch roads is analyzed on a year-on-year basis through a combination of graphical representations and reports, with daily, monthly, and annual breakdowns.
3.3.6 Energy Flow Diagram
The Energy Flow Diagram showcases the energy flow from source to end in a single building during a specific period, supporting views in both raw values and normalized values.
3.3.7 Nighttime Energy Consumption Analysis
The nighttime energy consumption is statistically compared in terms of tables, curves, and pie charts for the selected branch circuits' energy usage during working hours and non-working hours, supporting report export.
3.3.8 Equipment Management
Equipment management includes functions such as equipment types, inventory records, and maintenance logs. It assists users in managing equipment rationally to ensure smooth operation.
3.3.9 User Report
Users report that the system automatically calculates the monthly usage trends of various energies for selected buildings, along with simple energy consumption analysis results. A separate analysis of energy consumption with compound tariffs is provided for electricity usage, and the report is editable.
Conclusion
Through statistical analysis of the installed power of auxiliary machinery in spinning mills and measurements of the power consumption for main machines and air conditioning/dust removal systems, it was found that the installed power of the new air conditioning and dust removal system for spinning (excluding refrigeration) accounts for 18.2% of the total installed power in the mill. Under the automatic control system for air conditioning, the average actual power consumption takes up 20.2% of the total power in the mill, making the air conditioning system a crucial part of energy-saving management. Actual power consumption tests and statistics for the dust removal system of the cleaning and combing unit and the cotton picking system of the precision carding unit revealed that the actual power consumption of the dust removal and cotton picking systems accounts for 46.7% to 58.7% of the total power consumption. The energy-saving measures for the auxiliary machines of the cleaning and combing unit and the precision carding unit should also be given due attention.
For modern spinning mills, the adoption of mature energy-saving technologies, such as the use of constant-pressure variable-flow speed control in dust removal and carding cotton collection systems, and single-spindle correlation technology for controlling the operating frequency of fine yarn cotton extraction fans, has optimized the frequency of fine yarn concentration spinning fans. Scientific scheduling for processes like pre-spin carding, taking full advantage of peak, off-peak, and valley electricity prices, and adjusting production timing nodes, has yielded significant energy-saving effects. Taking our research-based enterprise as an example, implementing these technologies and management measures can achieve an annual electricity saving of 3.194 million kWh for the entire factory.
The company has achieved a comprehensive energy-saving effect of 5.7% with a power consumption of kW·h.
Reference
Gao Long, Zhou Yide. Modern Textile Air Conditioning Engineering [M]. Beijing: China Textile Press, 2018: 41-56.
Zhao Rongyi, Simplified Air Conditioning Design Manual [M]. Beijing: China Architecture & Building Press, 1998: 59-60.
Zhao Nannan, Wang Suying, Zhou Yide, Wang Chao gen. Quantitative Analysis of Energy Consumption in Modern Spinning Mills and Energy-saving Measures[J].
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