Energy-saving technology for mixed-flow high-efficiency turbines in industrial cooling towers
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Energy-saving technology for mixed-flow high-efficiency turbines used in industrial cooling towers I. Name of the technology: Mixed-flow turbine technology for industrial cooling towers II. Scope of application: Renovation of mechanically ventilated cooling towers in industries such as chemicals, metallurgy, and light textiles, where gravitational potential energy can be utilized III. Current energy consumption in the production processes related to this energy-saving technology: The current electricity consumption in industrial circulating cooling systems is such that each cooling tower is equipped with an electric motor to drive the fans inside the tower. A cooling tower with a flow rate of 4500 t/h consumes approximately 1.75 million kWh of electricity per year, which corresponds to an energy consumption of 612 tce. IV. Technical details: 1. Technical principle: The driving force for the operation of the turbine comes from the gravitational potential energy of the water in the circulating cooling water system, as well as the excess head provided by the circulating water pump. During operation, the technical parameters of the cooling tower are maintained, and the energy consumption of the circulating water pump remains constant. The output shaft of the turbine is directly connected to the fan, driving it to rotate; this eliminates the previous motor-driven fan system and saves electrical energy. 2. Key technologies 1) Using the residual pressure of circulating water to drive the turbine, in place of a motor ； 2) An ultra-low speed ratio mixed-flow turbine with a speed ratio of 50, whose efficiency is increased to over 88%; the original double-row circular guide vane array is replaced by a single-row circular one, and a metal elliptical volute is designed to achieve a compact structure for the turbine, thereby meeting the requirement of limited space inside the cooling tower. 3. Process Flow Reform process: Remove the cooling tower’s reduction gearbox and motor -> Install the cooling tower’s water turbine on the foundation of the original reduction gearbox -> Install the original fan -> Connect the water inlet pipe to the turbine’s inlet -> Connect the water distributor to the turbine’s outlet. V. Main technical specifications: 1) Turbine efficiency η ≥ 88%; the dimensional design meets the requirements for operation inside the cooling tower ； 2) Noise reduced by 20% ； 3) Replacing the motor with a turbine results in a 100% power savings. VI. Application of technology: It has been applied in industries such as petroleum, chemicals, steel, and light textiles. Energy-saving upgrades have been carried out on the cooling towers of hundreds of enterprises across the country, with significant energy savings achieved. VII. Typical Users and Investment Benefits: Typical users include Daqing Petrochemical, Yangzi Petrochemical, Baling Petrochemical, Harbin Petrochemical, Cangzhou Dahuahua, Shenjiu Chemical Fibers, Yizheng Chemical Fibers, Nanjing Iron and Steel, Jinan Iron and Steel, Jiangsu Shagang, etc. 1) Harbin Petrochemical. Construction scale: Renovation of 2 counter-current mechanically ventilated cooling towers with a capacity of 4000 t/h each. Main technical upgrades: Replace fan motors with water turbines, as well as transmission shafts and reducers; the main equipment consists of two HL4000 type water turbines for cooling towers. The investment in energy-saving technical upgrades is 2.4 million yuan, with a construction period of 15 days. The annual electricity savings amount to 3.168 million kWh (based on 330 days of operation per year), which is equivalent to 1,108.8 tce; the annual cost savings in electricity expenses amount to 1.9 million yuan, with a payback period of 1.3 years. 2) Jiangsu Shagang Huaiyang Special Steel. Construction scale: Renovation of one counter-current mechanically ventilated cooling tower with a capacity of 2500 t/h. Main technical upgrades: Replace the fan motor with a water turbine, as well as the drive shaft and reducer; the main equipment is one HLW-2500 type water turbine for cooling towers. The investment in energy-saving technological upgrades is 750,000 yuan, with a construction period of 10 days. It saves 871,000 kWh of electricity per year, which is equivalent to 304.8 tce (based on electricity costs calculated over 330 days of operation per year); the annual savings in electricity costs amount to 523,000 yuan (at a corporate electricity rate of 0.6 yuan/kWh), with a payback period of 1.4 years. VIII. Promotion prospects and energy-saving potential: The total capacity of existing cooling towers across the country that can be modified to incorporate turbines is approximately 241.57 million tons. It is estimated that by 2015, 10% of these towers will have been modified, resulting in over 6,000 sets being upgraded. This would enable an annual energy savings of 2.4 million tce, with a total investment of around 7 billion yuan.
The balance of the circulating water system is calculated separately for that system. The balance in a circulating water system is primarily achieved by balancing the water supply from the cooling tower with the evaporation from the cooling tower, as well as losses due to splashing, leakage, and wastewater discharge. That is: Water replenishment amount M = Evaporation amount E + Wind-induced loss amount D + Waste discharge amount B + Leakage amount F. The water replenishment amount for a cooling tower: With the water replenishment valve closed, it should equal the amount of water that has decreased in the various tanks during the period when the valve was closed. The water loss due to wind, denoted as D, can be calculated using the following formula: (1) Water loss due to wind D – As a result of air movement, some water droplets are carried away by the air. The water loss due to wind, D, is about 0.1% of the total circulating water volume. That is: D = R * 0.1%. Using this value, it is possible to calculate the wind loss for each recirculating water system. (2) Waste water volume B: The amount of water that must be artificially discharged in order to control the concentration process caused by evaporation during the cooling water circulation. The amount of circulating water discharged from each water usage workshop is measured using the volume method, while the amount of water discharged from the backwashing filters in the circulating water area is determined based on the number of times these filters are cleaned; in this way, the wastewater discharge volume for each circulating water area can be determined. (3) The leakage amount F is determined using the previous calculation formula: Water replenishment amount M = Evaporation amount E + Wind-induced loss amount D + Waste discharge amount B + Leakage amount F. Thus, the evaporation amount E can be calculated. (4) The loss coefficient C is determined based on the formula for calculating the evaporation amount E. The formula for evaporation amount E is: E = α(R – B) t/h, where: α – Evaporation loss rate, %; α = C(T1 – T2)%; R – Circulating water volume in the system, t/h ； B---Wastewater discharge volume, t/h ； E---Evaporation volume, t/h ； T1, T2—represent the temperatures of the circulating cooling water as it enters and exits the cooling tower. The flow rate R of the circulating water in each circulation system is determined based on the cold water meters associated with that system, or through the metering devices in the various workshops that use this circulating cooling water. The temperatures of the circulating cooling water entering and leaving the cooling tower are measured on-site using thermometers. Subsequently, the temperature coefficient C is determined to check whether it falls within the range of the loss coefficient corresponding to the ambient temperature; if so, it indicates that the measured amount of water to be added is correct, and on this basis a balance diagram for the circulating water system is prepared. The loss coefficient C is related to seasonal temperatures as follows: it is 0.15–0.16 in summer (25–30 degrees), 0.06–0.08 in winter (-15–10 degrees), and 0.10–0.12 in spring and autumn (0–10 degrees). The water storage capacity is generally 1/3 to 1/5 of the circulating water volume
I wonder if you have truly researched and understood this technology
This technology is suitable for cooling water plant designs with a large margin of tolerance:
Moreover, both the newly installed circulating water systems and the frequency conversion upgrades for existing ones are highly advanced, resulting in a very small pressure margin
The key lies in the calculation of excess energy in the system; if anyone is interested, they can discuss this with me