Wet non-woven fabric, with its strong adaptability to raw materials and uniform and soft products, has seen a surge in demand in hygiene products, medical protection, and other fields. However, its production characteristics of “high water and energy consumption” also pose severe challenges to energy conservation and emission reduction. Data shows that traditional wet production lines can consume 100-200 tons of water per ton of product, with drying accounting for over 50% of energy consumption. The COD (chemical oxygen demand) concentration in wastewater discharge often reaches 300-800mg/L. Under the pressure of the “dual carbon” policy, process optimization has become the core path for enterprises to reduce costs, increase efficiency, and achieve sustainable development. This article will analyze the energy-saving and emission reduction plans for wet non-woven fabric production from three dimensions: water system, energy utilization, and raw material technology.
Water System Optimization: From “Water Consuming Households” to “Recycling Utilization”
Water is the core medium of wet production, and optimizing water treatment systems is of utmost importance for energy conservation and emission reduction. In traditional production lines, processes such as fiber dispersion, web making, and equipment cleaning require a large amount of fresh water, and direct discharge of wastewater not only wastes resources but also increases environmental treatment costs. The combination strategy of “graded recycling+deep treatment” can achieve efficient circulation of water resources.
1. Classification and recycling of wastewater: Utilize according to quality and reduce fresh water consumption
Based on the differences in wastewater pollution levels, construct a “three-level recycling system” to achieve cascade utilization:
First level recycling (low pollution water): The filtered water from the papermaking process and the initial cleaning water of the equipment have low pollutant content (COD<100mg/L). After simple filtration (such as screen filtration+activated carbon adsorption), they are directly reused in the fiber dispersion process, replacing 30% -40% of fresh water. After adopting this plan, a wet non-woven fabric enterprise in Zhejiang reduced its fresh water consumption from 150 tons/ton of product to 95 tons/ton, saving over 120000 tons of water annually.
Secondary recycling (moderately polluted water): The cleaning water after fiber loosening and bonding contains a small amount of fiber debris and additives (COD 200-400mg/L). After treatment with “air flotation+membrane filtration”, it is used for non productive processes such as equipment cooling and workshop cleaning, further reducing the demand for fresh water.
Third level treatment (highly polluted water): Wastewater containing a large amount of fiber residue and chemical additives (COD>500mg/L) is treated using a combination process of “anaerobic biological treatment+MBR membrane bioreactor”. After treatment, COD can be reduced to below 50mg/L, meeting the requirements of the “Emission Standards for Water Pollutants in Textile Dyeing and Finishing Industry” (GB 4287-2012). Some of it can be used as reclaimed water to supplement the first level recovery system, achieving the goal of “zero discharge”.
2. Upgrading water-saving equipment: reducing water consumption from the source
The traditional wet screen forming machine uses continuous water spraying for screen curtain flushing, which consumes a large amount of water and has low flushing efficiency. Replace with a “pulse type high-pressure spray system”, which can reduce the amount of flushing water by 25% -30% while ensuring the cleanliness of the mesh curtain through intelligent control of spray frequency and pressure. In addition, using a combination device of “extrusion vacuum dehydration” instead of a single vacuum dehydration can increase the dewatering rate of the fiber web from 60% to 85%, reduce the amount of water evaporation in the subsequent drying process, and indirectly reduce energy consumption.
Energy utilization optimization: targeted consumption reduction, solving the pain points of “high energy consumption”
The energy consumption of wet non-woven fabric production is mainly concentrated in three stages: drying (50% -60%), motor drive (20% -25%), and heating (15% -20%). Through “waste heat recovery+intelligent temperature control+clean energy substitution”, the energy efficiency of the entire process can be improved.
1. Drying process: Waste heat recovery is the core breakthrough point
The hot air dryer is the “big head” of energy consumption, and the exhaust gas temperature discharged by traditional equipment is as high as 80-120 ℃, resulting in serious heat waste. Installing a “finned heat exchanger” at the exhaust port of the dryer can use the waste heat in the exhaust gas to preheat fresh air, which can increase the inlet air temperature by 30-50 ℃ and reduce the energy consumption of the heater. After a Jiangsu enterprise introduced this technology, the energy consumption in the drying process decreased from 280kWh/ton of product to 200kWh/ton, saving over 800000 kWh of electricity annually.
For high-end wet production lines, “heat pump drying technology” can be used to replace traditional electric heating or coal-fired heating. A heat pump absorbs low-level thermal energy from the environment, compresses it, and converts it into high-level thermal energy for drying. Its energy efficiency ratio (COP) can reach 3-4, which means that consuming 1kWh of electricity can generate 3-4 kWh of thermal energy, saving more than 50% energy compared to traditional methods. Although the initial equipment investment increases by 30% -40%, the cost can usually be recovered through energy-saving benefits within 2-3 years.
2. Motor and power system: frequency conversion transformation+permanent magnet motor upgrade
The traditional operating mode of motor equipment such as fans, water pumps, and conveyor belts in the production line is mostly “full load operation”, resulting in energy waste. Perform frequency conversion transformation on the main motor and adjust the speed in real time according to the production load: for example, when the production speed decreases from 300m/min to 200m/min, the fan speed synchronously decreases, and energy consumption can be reduced by about 40%.
In addition, replacing traditional asynchronous motors with permanent magnet synchronous motors can increase efficiency by 5% -10%. After upgrading 12 main motors, a wet process enterprise in Shandong province saved an average of 32000 kWh of electricity per month and over 250000 yuan in annual electricity bills.
3. Clean energy substitution: collaborative application of photovoltaics and biomass energy
Construct a distributed photovoltaic power station on the roof of the factory building, utilizing solar energy to provide partial power for the production line. Taking a wet non-woven fabric enterprise with an annual output of 10000 tons as an example, the annual power generation of a 10000 square meter rooftop photovoltaic power station is about 1.2 million kWh, which can meet 10% -15% of the enterprise’s electricity demand and reduce carbon emissions by about 960 tons per year.
For enterprises with conditions, “biomass fuel” can be used instead of coal or natural gas for heating. Biomass pellets made from straw, sawdust, and other materials are used as fuel, with a combustion efficiency of over 85%, and carbon emissions far lower than fossil fuels. At the same time, they can enjoy national renewable energy subsidy policies.
Optimization of raw materials and process parameters: reducing energy conservation and emission reduction pressure from the source
In addition to the renovation of water and energy systems, precise control of raw material selection and process parameters can reduce resource consumption and pollutant emissions from the production source.
1. Raw material upgrade: application of regenerated fibers and bio based fibers
Traditional wet production often uses native synthetic fibers, which not only have high raw material costs, but also result in high carbon emissions during the production process. Increasing the amount of recycled fibers (such as recycled polyester and recycled viscose) can reduce the energy consumption of primary fiber mining and processing. Data shows that for every ton of recycled polyester fiber used, 7.2 tons of crude oil can be saved and 10.9 tons of carbon emissions can be reduced. After a certain enterprise increased the proportion of recycled fibers from 20% to 50%, the carbon emissions at the raw material end per ton of product decreased by 35%.
In addition, the application of bio based fibers such as polylactic acid PLA and bamboo fiber is a future trend. Polylactic acid fiber is made from crops such as corn and sugarcane, and is completely biodegradable. The energy consumption during the production process is 30% lower than that of synthetic fibers. At present, PLA wet non-woven fabric has been applied in biodegradable wet wipes, medical dressings and other fields. Although the cost is 20% -30% higher than traditional products, it conforms to environmental policy guidance and market demand.
2. Precise control of process parameters: replace “excessive processing” with “moderate production”
By optimizing key parameters such as fiber suspension concentration, water jet pressure, and drying temperature, resource consumption can be reduced while ensuring product quality
Optimization of suspended slurry concentration: Traditional concentration is controlled at 0.5% -1%. Excessive concentration can lead to uneven web formation, while insufficient concentration can increase dehydration and drying loads. By using an online concentration monitoring system, the concentration can be stabilized at 0.8% -0.9%, which can reduce drying energy consumption by 10% while ensuring grid uniformity.
Water jet pressure grading regulation: According to the weight requirements of the product, a grading water jet process of “low-pressure pre piercing+medium pressure main piercing+high-pressure shaping” is adopted to replace the traditional single high-pressure water jet. For example, when producing a 40g/m ² wet wipe substrate, reducing the pre piercing pressure from 120bar to 80bar and maintaining the main piercing pressure at 100bar can reduce water piercing energy consumption by 20% without affecting product strength.
Drying temperature gradient control: Adopting a gradient drying mode of “low temperature high air volume+high temperature low air volume”, surface moisture is removed at a low temperature of 60-70 ℃ in the initial stage, and internal moisture is removed at a high temperature of 100-110 ℃ in the later stage. Compared with traditional constant temperature drying, energy consumption can be reduced by 15% -20%, while avoiding performance degradation caused by local overheating of the product.
Case study: Energy saving and emission reduction renovation practice of a certain enterprise
A wet non-woven fabric enterprise with an annual output of 20000 tons (mainly engaged in wet wipe substrates and medical dressings) will launch energy-saving and emission reduction renovation in 2023, investing 8 million yuan to implement the following measures:
Construct a “three-level wastewater recycling+MBR membrane treatment” system to increase the wastewater reuse rate from 20% to 65%, reduce fresh water consumption from 160 tons/ton to 60 tons/ton, save 2 million tons of water annually, and reduce wastewater treatment costs by 40%;
Install a waste heat recovery device and replace it with a heat pump dryer in the drying process, reducing energy consumption from 300kWh/ton to 180kWh/ton and saving 2.4 million kWh of electricity annually;
Motor frequency conversion renovation and photovoltaic power station construction, saving 1.5 million kWh of electricity annually and reducing carbon emissions by 1200 tons;
The usage of recycled fiber has increased from 30% to 60%, and the carbon emissions at the raw material end have been reduced by 42%.
After the transformation, the comprehensive cost of each ton of product in the enterprise decreased by 1200 yuan, and the annual profit increased by 24 million yuan. At the same time, it passed the EU ecological label certification, and the export volume of products increased by 35%, achieving a win-win situation of “environmental benefits+economic benefits”.
Challenge and Prospect: Building a Green Ecology for Wet Production
Although significant progress has been made in optimizing the production process of wet non-woven fabrics, there are still three major challenges: firstly, high-end energy-saving equipment (such as heat pump dryers and MBR membrane modules) rely on imports, resulting in high costs; Secondly, the quality stability of recycled fibers is insufficient, which affects product consistency; Thirdly, small and medium-sized enterprises face significant financial pressure and insufficient motivation for transformation. In this regard, the government, enterprises, and research institutions need to work together to:
At the policy level, increase subsidies for energy-saving renovations, establish a special fund for green manufacturing, and provide tax reductions and exemptions for enterprises that meet the standards;
Technical aspect: Strengthen industry university research cooperation, break through domestic high-end equipment and recycled fiber modification technology, and reduce transformation costs;
At the industry level: Establish an energy-saving and emission reduction standard system for wet non-woven fabrics, promote advanced cases, and form industry consensus.
In the future, with the maturity of “water energy material” collaborative optimization technology and the popularization of digital and intelligent control systems, wet non-woven fabric production will gradually achieve a green transformation of “low consumption, high efficiency, and environmental protection”, providing important support for the achievement of the dual carbon goals of the textile industry.
The energy-saving and emission reduction of wet non-woven fabric is not a single link transformation, but a full chain optimization of “water system, energy, raw materials, and process”. From the recycling of wastewater to efficient recovery of waste heat, from the promotion of regenerated fibers to precise control of process parameters, every optimization step is an important step for enterprises to move towards green manufacturing. Against the backdrop of increasingly strict environmental policies and growing demand for green products in the market, companies that optimize their processes in advance will gain a first mover advantage. Has your company initiated energy-saving and emission reduction renovations? Welcome to share your experience and confusion in the comment section!
Dongguan Liansheng Non woven Technology Co., Ltd. was established in May 2020. It is a large-scale non-woven fabric production enterprise integrating research and development, production, and sales. It can produce various colors of PP spunbond non-woven fabrics with a width of less than 3.2 meters from 9 grams to 300 grams.
Post time: Sep-02-2025