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How to dry fresh cocoons? --Drying stage of Silkworm Cocoon Dryer Machine

Views: 176     Author: Site Editor     Publish Time: 2021-07-21      Origin: Site


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Silkworm cocoon drying requires to kill pupae in time to prevent maggots, moths, steaming and mildew; reasonable drying technology is adopted to dry the pupa and protect the cocoon layer during the drying process of silkworm cocoons, taking into account the requirements of silk reeling and storage So that the drying degree is suitable and even, to prevent aging and tenderness; reduce consumption, reduce emissions, and improve equipment utilization and labor productivity.

The fresh cocoons are dried in a cocoon dryer machine under constant drying conditions. The whole drying process of fresh cocoons can be divided into three stages according to the speed of water evaporation.


1. Preheating and drying stage

2. Isokinetic drying stage

3. Reduced drying stage

Preheating and drying stage

Dry the fresh pupae and destroy the waxy layer on the surface of the pupae. The fresh cocoon is heated by the Dryer Machine, and the heat energy penetrates the cocoon cavity through the cocoon layer to kill the pupa body so that the pupa body moisture enters the evaporation period. At this stage, the temperature will gradually rise but rise sharply. 

Isokinetic drying stage

The pupa body has the most water evaporation and the fastest evaporation rate. During this period, the diffusion rate of the pupa's moisture and the evaporation rate of the surface of the cocoon is in equilibrium, the temperature of the cocoon is lower than the air temperature in the drying room, and the temperature of the pupa is lower than the temperature of the cocoon again until the pupa's moisture diffusion rate Gradually lag behind the evaporation rate of the cocoon layer surface.

Reduced drying stage

As the moisture content of the cocoon decreases, the evaporation effect goes from the surface of the pupa body to the inside of the pupa body, and the water inside the pupa body gradually diffuses to the surface, vaporizes in the cocoon cavity, and diffuses outward through the cocoon layer. At this time, the amount of water evaporation and the heat used for evaporation are gradually reduced, and the evaporation of water is controlled by internal diffusion. The temperature of the cocoon layer and pupa gradually rises until it is in equilibrium with the dry bulb temperature of the air in the Dryer Machine. At this time, the evaporation of water from the cocoons stops. The water evaporation rate in this stage gradually decreases with the increase of drying time, which is called the deceleration drying stage. During this stage, the surface of the pupa body of the cocoon cannot be kept moist but presents a partially and partially moist mixed state, and As the wetted part of the surface decreases, the drying speed will also slow down.


Sichuan Nanchong Shouchuang Technology Development Co., Ltd is a high-tech enterprise specializing in the production of dryer machines for more than 40 years. Through technology, software, equipment and services, it helps industrial optimization, helps customers optimize their operations, and provides the mst suitabole dryer machines .

Sichuan Nanchong Shouchuang Technology Development Co., Ltd.

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