What are the classifications products of Electrolyzer ?
Electrolyzer consists of a tank, anode and cathode, most of which are separated by a diaphragm from the anode chamber and the cathode chamber. According to the different electrolytes, it is divided into three types: aqueous electrolytic tank, molten salt electrolytic tank and non-aqueous electrolytic tank. When the direct current passes through the electrolytic cell, an oxidation reaction occurs at the interface between the anode and the solution, and a reduction reaction occurs at the interface between the cathode and the solution to prepare the desired product. Optimal design of Electrolyzer structure and reasonable selection of electrode and diaphragm materials are the keys to improving current efficiency, reducing cell voltage, and saving energy consumption.
1. The form of aqueous electrolyzer can be divided into Membrane Electrolyzer and non-diaphragm electrolyzer. Membrane Electrolyzer is generally used. In the production of chlorate and the production of chlorine and caustic soda by mercury method, a diaphragmless electrolytic cell is used. Maximizing the electrode surface area per unit volume can increase the production intensity of the electrolytic cell. Therefore, the electrodes in modern diaphragm electrolyzers are mostly upright. The electrolyzer exhibits different performance and characteristics due to the material, structure, and installation of the internal components.
2. Molten salt electrolyzers are mostly used to produce low-melting-point metals, which are characterized by operating at high temperatures, and should try to prevent water from entering and avoid hydrogen ion reduction on the cathode. The high temperature of the electrolytic cell can be achieved by changing the electrode spacing to convert the electrical energy consumed by the ohmic voltage drop into heat energy. When electrolyzing molten sodium hydroxide, the tank body can be iron or nickel. The electrolysis of molten electrolyte containing chloride is often due to the inevitable introduction of a small amount of water in the raw material, which will cause the anode to generate moist chlorine gas, which has a strong corrosive effect on the electrolytic cell. The electrolytic cell for electrolyzing molten chloride generally uses ceramic or phosphate materials, and iron can be used for parts that are not affected by chlorine. The cathode and anode products in the molten salt electrolyzer are also required to be properly separated, and should be drawn from the bath as soon as possible to prevent the cathode product metal sodium from floating on the surface of the electrolyte for a long time, which will further interact with the anode product or oxygen in the air .
3. Because the non-aqueous electrolyzer is often accompanied by various complex chemical reactions when preparing organic products or electrolyzing organic substances, its application is limited, and there are not many industrializations. The generally used organic electrolyte has low conductivity and low reaction speed. Therefore, a lower current density must be used, and the distance between the poles must be minimized. The electrode structure adopting a fixed bed or a fluidized bed has a larger electrode surface area, which can improve the production capacity of the electrolytic cell.
According to the connection mode of the electrodes, the electrolytic cell can be divided into two types: unipolar and bipolar electrolytic cells. The electrodes of the same polarity in the monopolar electrolytic cell are connected in parallel with the DC power supply, and the polarity of the two sides of the electrodes are the same, that is, they are both anodes or cathodes at the same time. The electrodes at both ends of the bipolar electrolytic cell are respectively connected with the positive and negative electrodes of the DC power supply to become anodes or cathodes. When the current flows through the electrolytic cell through the electrodes connected in series, one side of the middle electrodes is the anode and the other side is the cathode, so it has bipolarity. When the total area of the electrodes is the same, the current of the bipolar electrolyzer is smaller and the voltage is higher, and the investment of the required DC power supply is less than that of the unipolar electrolyzer. Bipolar type generally adopts the structure of filter press, which is relatively compact. However, it is prone to leakage and short circuit, and the tank structure and operation management are more complicated than the unipolar type. The cross section of the monopolar electrolytic cell is generally rectangular or square, and the cylindrical shape occupies a large area, and the space utilization rate is low, so it is less used.