Study on the type selection of the hottest aluminu

2022-07-26
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Research on the drying type selection of aluminum hydroxide dry rubber filter cake

1 preface

as a unit operation, drying involves a wide range of industries, and there are many kinds of materials and different properties in the drying process. It is very important to select the most suitable drying equipment for drying materials; It is not only an important guarantee to obtain satisfactory and qualified products, but also has a direct impact on investment and energy consumption. In the selection of drying, the following aspects should be considered: the influence of heating methods (convection, conduction and radiation) on the drying process; The influence of operation intensity and pressure on drying process; Final performance and quality requirements of products; The nature of the dried material; Energy prices, etc. However, for a specific material, it is often difficult to determine the appropriate drying equipment by the above analysis method when there is no mature use experience or when the traditional drying equipment is to be modified and updated. At this time, it is still an effective method to obtain relevant data and information through experiments, so as to determine the drying equipment of the specific material. In this paper, the selection test of drying equipment for aluminum hydroxide dry rubber filter cake is discussed

2 experimental purpose

as the carrier of catalyst, dry rubber filter cake (aluminum hydroxide) is required to have a large specific surface area and pore volume. The inlet moisture content of the material is 80%, and the outlet moisture content is required to be ≤ 3%. According to the characteristics of materials, the rotary flash dryer, double paddle dryer and disc continuous dryer provided by Gongda Equipment Co., Ltd. were selected for this experiment. At the same time, oven drying was used in the laboratory for comparative analysis

the rotary flash dryer has the advantages of one-time drying of wet materials into qualified products with uniform particle size, high drying intensity, continuous operation, compact equipment, etc; However, there are many problems, such as high energy consumption, easy to destroy the crystal form of materials, and many post-treatment equipment. The conductive disc continuous dryer is a dryer with large and small hollow drying discs arranged alternately up and down. The disc is fixed, and the middle rotating shaft is equipped with a rake arm. Each rake arm is equipped with several rake blades, and the shaft drives the rake arm and blade to rotate. Reasonably configure the rake blades to make the materials on the small drying plate move from the center to the outer edge of the plate, and fall from the outer edge of the small plate to the next layer of large drying plate; Driven by the rake blade, the materials on the large plate move from the outer edge to the center of the plate, and fall from the center to the next layer of small drying plate. In this way, the product materials will be discharged from the bottom plate through the outlet. The dry moisture is drained from the top outlet. The dryer has the advantages of high thermal efficiency, low energy consumption, good adjustability and not easy to lose materials. Paddle dryer is also a kind of conduction drying equipment, and its main advantage is high thermal efficiency

purpose of this experiment:

assuming that the valve core is roughened ⑴ use rotary flash dryer, paddle dryer and disc continuous dryer to dry the rubber filter cake, and verify whether the physicochemical indexes of the dried products can meet the process requirements

⑵ the experimental results of the above three drying equipment are compared with the experimental results of the oven

⑶ make economic analysis of three kinds of drying equipment according to the requirements of production capacity

3 experimental results and analysis

the equipment provided by Gongda Chemical Equipment Co., Ltd. is φ 400mm × 1500mm rotary flash dryer, paddle dryer with heat transfer area of 2.5m2 and φ 800/6c disc continuous dryer. Two batches of dry glue (aluminum hydroxide) were used in the experiment, and the wet content was 75% ~ 80%. The drying experiments were carried out in three kinds of drying equipment and ovens. The experimental results are shown in Table 1.

as the catalyst carrier of alumina, the important technical indicators are pore volume and specific surface area. According to the above experimental results, the following conclusions can be drawn:

⑴ as the drying equipment for dry rubber, the pore volume, specific surface area and moisture content of the dried products fully meet the requirements of relevant technical indicators, and the thermal efficiency is high Low energy consumption

⑵ the technical indicators of products dried by paddle dryer and rotary flash dryer are not up to standard. During the drying process, the material of the paddle dryer is squeezed, so the hole capacity of the material becomes smaller

⑶ due to the light alumina, higher requirements are put forward for the subsequent separation equipment of rotary flash drying. Otherwise, as in the experiment, the product yield is low and the loss is about 10%

⑷ from the perspective of power consumption, the power consumption of the disc continuous dryer is very small, while the power consumption of the other two drying methods is large, resulting in the increase of product cost

to sum up, the important technical indexes of the dry products obtained by rotating flash evaporation and blade drying - pore volume and specific surface area are lower than the requirements of the technical indexes, and the dry glue has certain aging phenomenon. Therefore, these two dryers are not suitable for dry glue drying production equipment. As for the dry rubber products dried by the disc continuous dryer, its various technical indicators meet and exceed the requirements of relevant technical indicators, and its high thermal efficiency and low energy consumption make it an ideal dry rubber equipment. On the basis of experiments, we decided to use the disc continuous dryer produced by Gongda Chemical Equipment Co., Ltd. as the dry glue drying equipment

4 production practice

the material is aluminum hydroxide, the wet content is 75%, the drying medium is 0.35Mpa saturated steam, and the initial temperature of the material is 20 ℃. It is required that the wet content of the finished product after drying is ≤ 5%, and the output of the finished product is 80kg/h. After calculation, the evaporation water volume during drying is 224kg/h, and the heat required is 5.28 × 105kj/h, the drying area of the disc continuous dryer required is 38.1m2. Therefore, one gdpg2200/14b disc type continuous dryer produced by Shijiazhuang Gongda Chemical Equipment Co., Ltd. is selected, which is made of 304 stainless steel. The actual drying area of the equipment is 43.1m2, there are 14 layers of drying plates, the motor power is only 5.5kW, the spindle speed is 1 ~ 9r/min, and the floor area is 4 The graphene based heavy-duty anti-corrosion coating developed by the marine functional materials team led by xuequnji, a researcher of Ningbo Institute of materials technology and engineering, Chinese Academy of engineering, and wangliping, a researcher of Sinosteel, has achieved mass production and entered the stage of large-scale demonstration and utilization. The welding and acceptance specification for reinforcement JGJ 18 ⑵ 00310m2, with a price of 457000 yuan, plus a quantitative feeder for auxiliary equipment and a crusher, totalling 483000 yuan

The energy consumption cost of

80kg/h aluminum hydroxide product is:

steam consumption 3640kg/t product, steam cost 218 yuan/t product

installed capacity: 9.9kw (including quantitative feeder: 2.2kW, crusher: 2.2kW)

power consumption 99kw For h/t products, the electricity cost is 54 yuan/t

the total energy consumption cost is 272 yuan/t product

(Note: the electricity charge is calculated at 0.55 yuan/kw.h, and the steam charge is calculated at 60 yuan/T)

the equipment operates well in production. The operator has said that the measured load/time function is convenient for the degrees of freedom of all important structural members in operation, and all indicators of the product meet the relevant technical requirements. During drying, the materials enter from the upper part of the equipment and the products are discharged from the lower part. The air humidity in the equipment is wet up and dry down. The drying tail gas is discharged from the upper part of the equipment. The tail gas speed is about 0.2m/s. The material dust will not be discharged with the tail gas, which will not pollute the environment, and the product loss is very small. The thermal efficiency of the equipment is above 60%. The production practice has proved that the result of drying equipment selection through experiments is correct and the economic benefit is remarkable

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