Key words of the instrument: proportional nitrogen flow rate distributor, chlorine gas calibration method, unattended
A COD digestion instrument for high-chlorine wastewater that uses an imported equal-proportion adjustment distributor to control the nitrogen flow rate;
A high-chlorine wastewater COD digestion instrument that fully complies with the national standard HJ/T 70-2001 "Determination of Chemical Oxygen Demand of High-chlorine Wastewater-Chlorine Calibration Method";
Product development background:
The determination of COD in industrial wastewater generally refers to the national standard "Water Quality Determination of Chemical Oxygen Demand Dichromate Method" (HJ828-2017). However, for industrial wastewater containing higher concentrations of chlorides, such as oil extraction, dye chemical, For organic chlorinating chemicals, salt lake brine development industry wastewater, etc., when COD is measured under strong acid conditions, the chloride ions in it are easily oxidized by potassium dichromate, which will affect the accuracy of the measurement results. Therefore, for the determination of COD in high-chlorine industrial wastewater higher than 1000mg/L and less than 20000mg/L, it is generally required to comply with the HJ/T70-2001 "Determination of Chemical Oxygen Demand of High-chlorine Wastewater-Chlorine Calibration Method" standard.
Method principle:
Add a known amount of potassium dichromate solution and mercury sulfate solution to the water sample, and use silver sulfate as a catalyst in a strong acid medium. After 2 hours of boiling and reflux, use 1.10-phenanthroline as an indicator and use sulfuric acid Ferrous ammonium titrates the unreduced potassium dichromate in the water sample, and the amount of ferrous ammonium sulfate consumed is converted into the mass concentration of oxygen consumed, which is the performance COD. Take out the chlorine gas formed by the uncomplexed and oxidized part of the chloride ion in the water sample, and then absorb it with sodium hydroxide solution, add potassium iodide, adjust the pH to about 3~2 with sulfuric acid, and use starch as an indicator. Titration with sodium thiosulfate standard titration solution, the amount of sodium thiosulfate consumed is converted to the mass concentration of oxygen consumed, which is the chloride ion correction value, and the difference between the COD and the chloride ion correction value is the true water sample measured COD.
Instrument use:
Used for dechlorination and digestion of COD samples in high-chlorine waters (water and wastewater, with a chloride ion concentration greater than 1000mg/L, less than 20000mg/L).
Applicable industry:
COD measurement in high-chlorine wastewater such as oil fields, coastal refineries, oil depots, chlor-alkali plants, steel plants, power plants, pesticides, food, textile printing and dyeing enterprises, and deep-sea discharge of wastewater.
The main advantages of the product:
1. The heating unit adopts far-infrared ceramic heating technology, and the heating rate is stable and controllable;
2. Digestion unit: 1-6 positions, all can be single-hole single-control;
3. The nitrogen flow rate is controlled by an imported equal-proportion regulating distributor, the flow rate is evenly distributed, and the flow rate is stable;
4. The digestion time is controlled by a computer program, which can be set freely, and it can stop automatically when the digestion is finished;
5. The cooling system adopts built-in compressor for cooling, and the cooling water is automatically internally circulated without external cooling water;
6. The main machine is equipped with an automatic anti-back suction unit for nitrogen, which can prevent the absorption liquid from sucking back at the end of heating;
7. The whole machine adopts PLC module control, touchable LCD tablet computer, convenient and fast remote operation
