Coulter Air Lifter for Cellulose Ether Industry

A coulter-type air lifter capable of continuous operation is designed, which is mainly used as a dealcoholization drying equipment in the process of producing cellulose ether by solvent method, so as to realize effective and continuous operation of the dealcoholization drying process, and finally realize the goal of CMC production. Continuous operation.

Key words: carboxymethyl cellulose ether (CMC for short); continuous operation; coulter air lifter

0、Preface

In the traditional process of producing cellulose ether by solvent method, the crude product of carboxymethyl cellulose (hereinafter referred to as CMC) obtained by etherification reaction can be obtained by refining processes such as neutralization washing, drying treatment, crushing and granulation, etc. . Only part of the ethanol contained in the above crude CMC is recovered by distillation along with the sodium salt during the neutralization and washing process, and the other part of ethanol is retained in the crude CMC, dried, pulverized, granulated and packaged into finished CMC. recycle. In recent years, the price of organic solvents has continued to rise. If ethanol cannot be recycled, it will not only cause waste of resources, but also increase the production cost of CMC, which will affect product profits and reduce product competitiveness. In this context, some CMC manufacturers improve the process flow and use the rake vacuum dryer in the process of dealcoholization and drying, but the rake vacuum dryer can only be operated intermittently, and the labor intensity is high, which cannot meet the requirements of the existing CMC production. automation requirements. The R&D team of Zhejiang Provincial Research Institute of Chemical Industry has developed a coulter-type air stripper for the CMC dealcoholization and drying process, so that ethanol can be quickly and fully volatilized from the CMC crude product and recycled for use, and at the same time complete the operation of the CMC drying process. And it can realize the continuous operation of CMC production, and it is an ideal replacement equipment for rake vacuum dryer in the CMC production process.

1. Design scheme of coulter air lifter for cellulose ether industry

1.1 Structural features of coulter air lifter

The coulter type air lifter is mainly composed of transmission mechanism, horizontal heating jacket body, plow share, flying knife group, exhaust tank, discharge mechanism and steam nozzle and other main components. This model can be equipped with a feeding device on the inlet and a discharge device on the outlet. The volatilized ethanol is discharged through the exhaust tank and recycled for use, thereby realizing the continuous operation of CMC production.

1.2 Working principle of coulter air lifter

Under the action of the coulter, the CMC crude product turbulences along the inner wall of the cylinder in the circumferential and radial directions on the one hand, and is thrown along the normal direction of the two sides of the coulter on the other hand; when the stirring block material flows through the flying knife, It was also strongly scattered by the high-speed rotating flying knife. Under the combined action of coulters and flying knives, the CMC crude product is quickly rotated and crushed to increase the surface area where ethanol can be volatilized; at the same time, the material in the cylinder is heated by the jacket steam and the steam is passed into the cylinder to directly heat the material Under the double function of the ethanol, the volatilization efficiency and effect of ethanol are greatly improved, and the ethanol is separated quickly and thoroughly. At the same time of dealcoholization, the steam in the jacket heats the material in the cylinder and completes the drying process of CMC. thereafter. The CMC after dealcoholization and drying can enter the subsequent crushing, granulation and product packaging process after being discharged from the discharge mechanism.

1.3 Special coulter structure and arrangement

Through the research on the characteristics of CMC, the researchers chose to use the coulter mixer developed in the early stage as the basic model, and improved the structural shape and coulter arrangement of the coulter many times. The distance between two adjacent coulters in the circumferential direction The included angle is α, α is 30-180 degrees, arranged in a spiral on the main shaft, and the rear end of the coulter has an arc concave to enhance the splashing force of the material along the normal direction of the two sides of the coulter , so that the material is thrown and crushed as much as possible to increase the surface area where ethanol can be volatilized, so that the ethanol extraction in the CMC crude product is more sufficient.

1.4 Design of cylinder aspect ratio

In order to realize the continuous operation of the air lifter, the length of the barrel is longer than that of the general mixer. Through several improvements in the design of the ratio of the length to diameter of the simplified body, the optimum length-to-diameter ratio of the simplified body was finally obtained, so that the ethanol can be fully volatilized and supplied from the exhaust tank in time, and the operation of the CMC drying process can be completed at the same time. The CMC after dealcoholization and drying directly enters the process of crushing, granulation and product packaging, realizing the full-line automation of CMC production.

1.5 Design of special nozzles

There is a special nozzle at the bottom of the cylinder for steaming. The nozzle is equipped with a spring. When the steam enters, the pressure difference makes the nozzle cover open. When the steam is not flowing, the nozzle cover closes the nozzle under the tension of the spring to prevent the crude CMC from being released. Ethanol leaks from nozzle.

2. Features of coulter air lifter

The coulter-type air lifter has a simple and reasonable structure, can extract ethanol quickly and fully, and can realize the continuous operation of the CMC dealcoholization drying process, and is safe and easy to install, operate and maintain. Some customers have given feedback after using it. Using this machine not only has a high recovery rate of ethanol extraction and low energy consumption, but also improves product quality, reduces production costs, and saves ethanol resources. At the same time, it greatly improves working conditions and labor productivity, and meets the existing CMC requirements. Industrial production automation requirements.

3. Application prospects

In recent years, my country’s CMC industry is transforming from labor-intensive production to automated production, actively developing new equipment research and development, and continuously improving the process in combination with the characteristics of the equipment, so as to realize CMC production at low cost and prepare high-quality products. The common goal of CMC production enterprises. The coulter type air lifter greatly meets this requirement and is an ideal choice for CMC production tooling equipment.