Blow Room and Carding Filter's Exhaust Air Reuse for Significant Energy Savings

Blow Room and Carding Filter's Exhaust Air Reuse for Significant Energy Savings Abstract This paper explores the potential energy savings achievable in spinning mills by reusing the exhaust air from Blow Room and Carding department filters, which is typically wasted. Current mill designs rely on large air-conditioning systems that expel significant amounts of hot exhaust air, leading to increased energy costs. This research highlights how reusing this hot air can save a considerable amount of energy by reducing the load on supply fans and optimizing air circulation throughout the mill. The study suggests that altering the plant’s design can allow for year-round utilization of this hot exhaust air, resulting in substantial cost savings in energy consumption. 1. Introduction Efficient air management is crucial in spinning mills for maintaining optimal working conditions and ensuring smooth production processes. However, many mills overlook the potential for reusing exhaust air, particularly from Blow Room and Carding department filters, which can significantly reduce energy consumption. This paper discusses how reusing hot exhaust air from these areas can help mills save energy by reducing the need for additional supply fans and balancing air pressure within the plant. In most spinning mills, supply and return fans are designed based on the required air changes per hour. However, Blow Room and Carding departments typically have around 50 kW of supply fans installed, while the filters in these departments extract around 200 kW of air, creating an air imbalance that must be compensated by additional supply fans. 2. Problem with Current Air Management Systems In typical air-conditioning systems, the 200 kW of air extracted by Blow Room and Carding filters is expelled via rotary filters, leaving only 50 kW of supply fans to compensate for the air loss. This creates a vacuum, which forces the remaining supply fans in the mill to balance the department's air. The result is an energy-intensive system that requires additional fans to make up for the loss of air. During the summer, mills exhaust the hot air produced by Ring, Compact, and Auto Cone motors. This air, while dry, is wasted, and supply fans must compensate by bringing in external air, adding to energy consumption. However, this hot, dry air can be reused within the mill, providing an opportunity for significant energy savings. 3. Proposed Solution: Reusing Hot Exhaust Air The key to reducing energy consumption lies in reusing the hot exhaust air produced by filters and motor ventilation systems. Normally, this air is only reused in winter to increase the department’s temperature. However, this study shows that by altering the design of the plant, this hot exhaust air can be utilized year-round, saving substantial energy costs. Table 1 below shows the characteristics of the return fan air: Parameter Dry Bulb Temp (°F) Wet Bulb Temp (°F) Relative Humidity (%) Return Fan Air 104 85 44 This reuse of hot air saves only heating costs in winter because the air is supplied through the supply fan. The current design channels this hot air through the back of the supply fan, but a redesign could allow mills to save on supply air costs throughout the year. 4. Overcoming Common Objections One common argument against reusing hot exhaust air is that it must be water-treated before reintroduction into the department to ensure clean air. However, observations show that in winter, only 20% of the pump sprays water, meaning that 80% of the hot air enters the department without any water treatment. Therefore, this hot air can be reused even in summer, with the option of treating it with water as needed. 5. Energy-Saving Potential By reusing hot air from Blow Room and Carding filters and motor ventilation systems, mills can avoid the need for additional supply fans, which would typically require around 156 kW of energy. Additionally, this reuse reduces the load on the mill’s air-conditioning system, further lowering energy consumption. The cost savings from implementing this strategy can be substantial, particularly when applied year-round, rather than only in winter. 6. Conclusion Reusing the exhaust air from Blow Room and Carding filters, as well as motor ventilation systems, presents an effective method for reducing energy consumption in spinning mills. By modifying the design of the air-conditioning system to utilize this hot air throughout the year, mills can achieve significant cost savings in energy usage. This research demonstrates that the perceived need for water treatment of this air is not as critical as previously thought, and reusing this exhaust air can provide an efficient, sustainable solution for reducing operational costs. 7.