Improvement of the bleaching process with the most

2022-09-22
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Improvement of bleaching liquor making process with liquid chlorine

key words: liquid chlorine; Bleaching liquid; technological process; Improvement 1 Introduction to the old original process

our company uses the principle of liquid chlorine reacting with lime to produce calcium hypochlorite to make a self-made bleaching solution for the bleaching of wheat straw pulp, as shown in the original flow chart 1. In 2008, the apparent consumption of plastic in China was 51.914 million tons. The collection tank is a square structure, and the chlorine pipe is directly connected to the pump outlet pipe vertically, only 1.2m away from the pump outlet. Due to the dead corner of the absorption tank and the poor mixing of ash emulsion and liquid chlorine, local supercohlorination and chlorine gas are often caused to escape into the air, resulting in the loss of effective chlorine. Pump outlet 1. Due to the high hardness of the sample and the pressure greater than the internal pressure of the chlorine bottle, when the company will pay more attention to the investment power downstream of the industrial chain in the future, it often happens that the amount of chlorine left in the bottle is large and the grey water flows back into the bottle, causing bottle damage and unsafe factors

due to the small volume and area of the clarifier, our company often takes a long time to clarify, has a lot of slag discharge times, and has a large loss. Our clarifier and absorption tank have the same volume, only 20m3, the clarification area is 24m2, and the slag is discharged more than twice a day. The amount of slag discharged each time is 10m3, about 100kg of available chlorine is contained, and the loss of available chlorine is about 200kg per day

according to the existing scale, our company needs to prepare about 3 ~ 3.5t of effective chlorine every day, while it takes about 6 ~ 8h to clarify 1t of effective chlorine, about 40min to discharge the slag once, and about 2H to absorb 1t of effective chlorine. In total, it takes more than 9h to produce 1t of effective chlorine, making the production capacity seriously insufficient

ash storage platform → emulsifying pool → buffer pool → pump → absorption pool → pump → clarifier → storage pool ↑↓↑↓

chlorine in high-pressure water slag field → ejector ←←←↑ recovery pool → trench

Figure 1. The original process flow diagram and sketch of the hall

2. The improvement of the original process

the improved process flow of our company:

manually use high-pressure water to directly pump white ash into the emulsifying pool from the ash table, Labor intensity is greatly reduced. The ash flushing water pressure shall not be lower than 0.2MPa, otherwise the amount of residue will be increased. The absorption tank is changed into a conical bottom round tank, and an ejector is installed on the circulating pipe, as shown in Figure 2. The ejector is divided into three parts: air suction chamber, chlorine suction chamber and diffusion mixing chamber. After the pump is turned on, the grey water lotion enters the ejector to generate two-stage vacuum. The first stage inhales air and the second stage inhales chlorine. After the three are fully mixed at the outlet, it enters the absorption tank. The air entering the absorption tank is released, moving from bottom to top, driving the grey water to turn up and down, playing the role of mixing, which is conducive to the uniform mixing of chlorine and lime, and the turning intensity of grey lotion can be controlled by adjusting the amount of air inhaled, Prevent chlorine from escaping into the air in strict compliance with various health standards

Figure 2 Schematic diagram of the hall after improvement

our company increased the clarification area and capacity of the clarifier by three times, shortening the clarification time and reducing the number of slag discharge. It only takes about 5h to prepare 1t of effective chlorine. A recovery tank is added to clarify the diluted sediment for the second time, which can be recycled and reused. 200 ~ 250kg of effective chlorine can be recovered every day

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