October 29, 2010 (One Question per Day)

Purpose of furnace cleaning: Alkaline furnace cleaning is used to remove oil, sediment, and rust from within the equipment, ensuring uniform heating of the equipment. – The operation of the boiling furnace should be carried out according to the following procedure: Add 2–3 kg/m3 (H2O) of NaOH and 2–3 kg/m3 (H2O) of Na3PO4·12H2O ； ·Fill to the lowest level and add the required amount of the chemical prepared as a 20% solution ； ·Open the vent valve on the steam drum to introduce low-pressure steam into the drum in order to heat the boiler ； ·If a lower steam quality is required, cooking can be carried out at atmospheric pressure, thereby appropriately reducing the cooking time. When the water in the boiler drum boils and vapor emerges from the vent valve at the top, while steam is introduced from the bottom, the boiler is left to boil for 2 days; or the boiling process is considered complete once the alkalinity level has not changed after two consecutive tests ； During boiler operation, samples of the boiler water should be taken regularly to analyze its alkalinity; when the alkalinity is below 45 mmol/L, chemicals should be added to compensate for it ； ·Once the boiler has been boiled, close the steam valve, and use deoxygenated water to continuously supply water and remove waste water in order to flush the interior of the boiler drum as well as the valves and pipes that have come into contact with the chemicals, until the water quality meets the operational standards. – Records should be kept, and these records should include at least the following information: operation time ； Brief description of the furnace boiling process ； Issues Found ； Rectification results ； Signed by the executor/responsible person

The purpose of boiling the pot is to remove rust, iron scum, grease, and dirt from it. Ensure the interior of the heating surface remains clean to obtain steam of qualified quality. 1. Operation of the cooking pot: (1) For a pot with a volume of 1 cubic meter (m3), add 2–3 kilograms of trisodium phosphate (Na3PO4·12H2O), or 3–4.5 kilograms of sodium carbonate (Na2CO3), along with 2–4 kilograms of sodium hydroxide (NaOH). Solid drugs must not be added directly into the boiler drum; instead, they should be dissolved in water under pressure-free conditions, and then pumped into the boiler drum using a pump. (2) The boiler should be kept at near the maximum water level during boiling. Use the method of draining waste water to gradually replace the water in the pot. Reduce combustion when discharging waste. (3) During boiling, maintain a rated evaporation rate of 5% to 10%, and discharge the generated steam using the exhaust valve on the boiler drum or by lifting the safety valve. For small and medium-sized low-pressure boilers, the boiler needs to be kept running for 1–3 days. (4) The boiling pot is allowed to heat up until steam is generated, a process that lasts 10–12 hours; after 12 hours, the burning intensity is increased, and this continues for 1–3 days. After shutting down the furnace, it must be cooled to a water temperature of 70°C before the water is drained; thereafter, the interior of the boiler should be rinsed clean with water. 2. Precautions for using the boiling pot: (1) Personnel preparing the chemical solution should wear rubber boots, rubber gloves, rubber aprons, and protective masks to avoid burns from the alkaline solution. (2) When boiling the pot, replace the water using the drainage method; the drainage time at each drainage point should not be too long. The make-up water should also be supplied evenly and slowly to prevent damage to the water quality inside the boiler. (3) Use only one water level gauge when boiling the pot; the others are for backup. The boiler water level is maintained close to the maximum level, but it is not allowed for alkaline water to enter the superheater. (4) After the boiler stops operating, all manholes on the boiler drum, the lower header of the water wall, and the economizer header must be opened to carry out an internal inspection and cleaning, as well as to check whether the blowdown valves are clogged. (5) The inner walls of the boiler drum and header must be free of oil stains and rust to be considered qualified.

Sodium hydroxide titrant (1, 0.5 or 0.1 mol/L) 　　NaOH = 40.00　　　　　　　　　　　　　　40.00 g → 1000 ml 　　20.00 g → 1000 ml 　　4.000 g → 1000 ml 　　【Preparation】 　　Take an appropriate amount of sodium hydroxide solution, add water and shake to dissolve it to form a saturated solution. After cooling, transfer it to a polyethylene plastic bottle and let it stand for several days; once it has become clear, it can be used. 　　Sodium hydroxide titrant (1 mol/L): Take 56 ml of a clear saturated solution of sodium hydroxide, add freshly boiled cold water to bring the volume to 1000 ml, and mix well. 　　Sodium hydroxide titrant (0.5 mol/L): Take 28 ml of a clear saturated solution of sodium hydroxide, and add freshly boiled cold water to bring the volume to 1000 ml. 　　Sodium hydroxide titrant (0.1 mol/L): Take 5.6 ml of a clear saturated solution of sodium hydroxide, and add freshly boiled cold water to bring the volume to 1000 ml. 　　【Calibration】 Sodium hydroxide titrant (1 mol/L): Take about 6 g of reference potassium hydrogen phthalate, dried to a constant weight at 105°C, weigh it accurately, add 50 ml of freshly boiled cold water, and shake to ensure complete dissolution ； Add 2 drops of phenolphthalein indicator, and titrate with this solution ； Near the end, potassium hydrogen phthalate should be completely dissolved, and titration is continued until the solution turns pink; at that point, the process is complete. Each 1 ml of sodium hydroxide titrant (1 mol/L) is equivalent to 204.2 mg of potassium hydrogen phthalate. The concentration of this solution is calculated based on the consumption amount of this solution and the amount of potassium hydrogen phthalate used. 　　Sodium hydroxide titrant (0.5 mol/L): Take about 3 g of reference potassium hydrogen phthalate dried to a constant weight at 105°C, and standardize it according to the above method. Each 1 ml of sodium hydroxide titrant (0.5 mol/L) is equivalent to 102.1 mg of potassium hydrogen phthalate. 　　Sodium hydroxide titrant (0.1 mol/L): Take about 0.6 g of reference potassium hydrogen phthalate dried to a constant weight at 105°C, and standardize it according to the above method. Each 1 ml of sodium hydroxide titrant (0.1 mol/L) is equivalent to 20.42 mg of potassium hydrogen phthalate. 　　If a sodium hydroxide titrant (0.05, 0.02, or 0.01 mol/L) is required, it can be prepared by diluting sodium hydroxide titrant (0.1 mol/L) with freshly boiled cold water. If necessary, the concentration can be calibrated using hydrochloric acid titrant (0.05, 0.02, or 0.01 mol/L). 　　【Storage】 Store in a polyethylene plastic bottle, keeping it sealed ； There are 2 holes in the plug; a glass tube is inserted into each hole. One of these tubes is connected to the soda-lime tube, while the other is used for drawing out the liquid.