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The copper electrolysis process is a mature traditional technique, and the process conditions used by different manufacturers are generally similar; however, there are significant differences in energy consumption within the factories. The company has successively built five electrolysis workshops, continuously improving their design with an emphasis on energy conservation, which has laid the foundation for reducing energy consumption in production. The consumption of cathode copper vapor and direct current has decreased from 800 kg/t and 330 kwh/t at the beginning of plant operation to 380 kg/t and 272 kwh/t today; the vapor consumption has dropped by 52.5%, while the direct current consumption per unit volume has decreased by 17.6%. When designing the electrolysis plant, measures were taken in the following main areas: 1. Temperature control: In the process of copper electrolysis, the electrolyte plays a role in mass and heat transfer as well as in electrical conduction. Maintaining a certain temperature of the electrolyte is a basic requirement of the production process, with the temperature generally kept between 55°C and 65°C. There is a large temperature difference with the environment, resulting in rapid heat loss and high steam consumption. To reduce the heat loss from the electrolyte, we have taken the following measures: 1. Provide comprehensive insulation for the electrolyzer. The electrolyzers used by our company are made of reinforced concrete with a fiberglass lining; their average wall thickness is 90 mm. During normal operation, the temperature of the electrolyte inside the electrolyzer is 60°C, while the temperature of the outer wall reaches 40°C, resulting in rapid heat loss. Subsequently, the bottom and both ends of the electrolyzer were insulated using polyurethane insulation material, with an insulation thickness of 40 mm; after insulation, the surface temperature of the insulation layer was roughly the same as the ambient temperature ； For the groove surface area, many different covering materials were tested. By comparing their thermal insulation properties, heat resistance, and water permeability, a woven fiber fabric proved to be the most suitable option – it allows water to pass through, is resistant to heat, and has a long service life. Electrolyzers that adopt external wall insulation, pipeline insulation, and trough surface covering measures achieve significant energy-saving effects. 2. Insulation for the low-level tank: The company’s electrolyte circulation low-level tanks are also constructed with a reinforced concrete core lined with fiberglass; all four walls are insulated using insulation material with a thickness of 40 mm. A flexible rubber sheet is placed over the top of the tank. To avoid having to lift this rubber sheet frequently for level checks, we installed level indicators that indicate the normal, upper, and lower limits of the liquid level. This not only solves the issue related to the covering but also facilitates the monitoring and adjustment of the liquid level. 3. Choose high-efficiency heat exchange equipment. The heating of the electrolyte is generally achieved by using steam to drive heat exchange through a heat exchanger. The efficiency of this heat exchange has a significant impact on the amount of steam required. Especially when the electrolyte contains many components that tend to cause scaling, a layer of scale will form on the cooling surfaces of the heat exchanger in a short period of time, which reduces the heat exchange efficiency. Therefore, when selecting a heat exchanger, it is necessary to consider whether the layout of the flow channels in the plates is reasonable, whether it is easy to clean the device, and whether the plates and gaskets can be removed frequently. It is also necessary to consider the possibility of using hot water resources for heat exchange. If suitable hot water resources are available, the required plate area for the heat exchanger must be determined based on the heat transfer coefficient of hot water, as well as the flow rate and resistance of the hot water. Plate heat exchangers offer advantages such as high heat exchange efficiency, small floor space, and ease of disassembly and cleaning; as a result, they are being used more and more widely in copper electrolysis production, providing good energy-saving effects. II. Power Saving In the copper electrolysis production process, electricity consumption accounts for over 60% of the total energy consumption, and the level of electricity use has a direct impact on the production costs of enterprises. The company has taken the following three main measures to save electricity: 1. Choosing efficient rectifier power supplies. Rectifier power supplies are the core equipment in electrolytic production, serving to rectify and stabilize the current. Usually, when choosing rectification equipment, we only pay attention to whether the output voltage and current capabilities are suitable, without giving much consideration to the conversion efficiency of rectification. In reality, a 1% difference in this aspect can result in significant losses over time. Taking an electrolysis plant with an annual production capacity of 40,000 tons as an example: assuming a direct current consumption of 275 kwh per ton, the annual electricity usage is 1.1×107 kwh; 1% of that amount is 1.1×106 kwh. At an electricity price of 0.5 yuan per kwh, the loss amounts to 55,000 yuan per year, or 550,000 yuan over 10 years. Therefore, when selecting rectification equipment, its conversion efficiency must be taken into account. According to the requirements of the national standard \"Guidelines for Evaluating Rational Power Consumption Techniques in Enterprises (GB/T 3485-1998)\), for DC voltages of 100V or higher, the conversion efficiency should be above 95%. The voltage regulation step size should also be taken into consideration to avoid an excessively large triggering angle; the starting voltage as well as the number of stages in the load-switching device should be selected appropriately, so that the triggering angle remains within 25º during normal operation (applicable to thyristor rectification equipment), thereby ensuring a high power factor. 2. Design of DC circuits The current used in electrolytic production is generally very high, ranging from a few thousand amperes to tens of thousands or even hundreds of thousands of amperes. With such high currents, if the cross-sectional area for electricity conduction and the layout of the circuits are not appropriate, losses become quite significant. Typically, the current density for DC copper bars in design is in the range of 1–1.1 A/mm2; in small refineries, where the current intensity is lower, a current density of 1.4–1.6 A/mm2 is used. However, calculations show that at 1.5 A/mm2 compared to 1 A/mm2, the former is more cost-effective in terms of investment; yet the latter reduces line losses during operation, allowing the additional cost of the copper bars to be recovered within 2 to 3 years. Since the lifespan of a set of rectification equipment is over 10 years, it is economical to choose a lower current density during design. At a current of 15,000A, the power loss per meter of copper bar is 270–400W; thus, the energy lost per meter of copper bar per year is 2,300–3,500kWh. Therefore, when designing copper bar circuits and arranging rectification equipment, it is important to keep the length of the copper bars as short as possible. Even a reduction of 1 meter in length can result in a considerable amount of energy savings on a permanent basis. 3. Select an appropriate pole distance and plate area. During the electrolysis process, the voltage drop across the electrolyte accounts for 30% to 67% of the cell voltage. According to the formula R=ρ•I/S, the pole distance in electrolysis is equivalent to I in the resistance formula, while the total area of the plates is equivalent to S. Therefore, during design, factors such as the operator’s skill level, degree of automation, and the quality requirements for polar processing should be taken into account to select a shorter pole pitch and a larger pole plate area. III. Conclusion Taking energy conservation fully into account during the design phase plays a key role in reducing energy consumption during future production processes; if the design is unreasonable, carrying out various modifications will result in significant economic losses. Therefore, adopting energy-saving design is beneficial for reducing energy consumption in products and protecting the ecological environment. This post was last edited by skybiue123 on 2009-3-23 17:21.]