Discussion on Several Methods of Removing Water from Bottle Surface

In the production line of the filling product, the external surface of the packaging bottle that is filled with good products (such as wine, soft drinks, etc.) shall be labelled, printed with ink, or packed. In order to achieve better results, it is required to dry the surface of the bottle. At present, in actual production, the bottle is generally dried or blow dried.

In the production, the drying generally uses a brush drying combination type or a hot oven drying type, and the brush bottle device mainly uses the brush to rotate to remove the bottle wall water droplets. Due to the contact treatment, bottle brushing effects are closely related to the bottle's appearance. Rotary body (such as cylinder) bottle brush works well, and non-revolving bodies and other special-shaped bottles have parts that are not in contact with the brush. After brushing the bottle, there is still a water film on the outer wall of the bottle. In addition, during use, the brush easily accumulates dirt and may be transferred to the outer wall of the bottle to affect the quality of the package. Hot oven drying type has simple structure and complete drying, but its thermal power is large, working temperature is high, and the area isolation is required when the automatic production line is arranged. When drying, the water takes a long time to completely evaporate, which is not suitable for high-volume online production. Production, and when the transmission system of the bottle, bottle, or the like is blocked during work, the bottle stays in the oven for too long, which may cause the bottle to burst. In addition, on the surface of products with higher cleanliness requirements, after the cleaning and rinsing processes, the drying method is generally not adopted. This is because not only the surface of the bottles can be kept dry, but also the product surface and the rinse water must be solved. Contamination caused by impurities and water spots after drying.

Blow drying method, that is, applying the advantages of pneumatic technology in the packaging process of the filling product, adopts a fan to complete the air flow accumulation and acceleration of the high pressure air flow through the air knife, and can use the air flow to blow off the water on the surface of the product. More domestic air knife drying programs include: using compressed air hot air to dry, blow with high-pressure air blower hot air, or blow with high-pressure hot air blower (using high-infrared tubes to make the heating head) and so on. This article has designed a new type of efficient cold air drying water removal equipment structure, using a high-pressure fan cold blow dry method, relying on the high-speed air jet nozzle blow out the bottle surface of the residual water to dry, without using any heating equipment .

The blow dry water removal equipment includes a high pressure blower, two special air knives and related accessories. The low-speed airflow blown by the fan passes through the fan to enter the chamber of the air knife, and then passes through the ever-decreasing cross-section air knife nozzle to form a high-speed air stream to be sprayed onto the surface of the bottle. Each special air knife is equipped with a spray height and an angle adjustment lever so as to be suitable for drying different shapes and sizes of bottles.

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The rated power of the fan used in the design is pt = 5.5kw, and the rated flow rate is L = 0.1467m3/s, ie m = 0.1768kg/s (at 20°C) and the rated pressure P = 0.3MPa. Assume that the fan is working under rated conditions, the ambient condition is 0.1 MPa, and the air temperature is T0=20°C. The airflow generated by the fan enters two air knife chambers on both sides of the filling product line via two pipe branches. Considering that the branch pipe is very short and the airtightness is very good, it can be considered that the air flow is discharged into the air knife and finally ejected. No air volume loss.

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In actual operation, the smaller the gap height of the air knife jet, the greater the resistance to the jet air flow and the more heat converted by the entire system, and the shorter the service life curve of the fan will be. Therefore, when setting the gap height, it is necessary to balance the air knife jet speed and the operating life of the fan. 

The shorter the injection port guide section, the better, in order to reduce unnecessary friction loss, but it should not be too short. It is better to use 3 times the design height of the gap, otherwise it will not achieve good guiding airflow jet effect and will make the injection site. The air flow cannot be focused on the surface of the bottle, causing the remaining water droplets to be blown off effectively.
In the process of drying the water removal equipment, the pressure and air volume characteristics of the fan are a curve. In the non-rated state, the air flow rate of the nozzle can be dynamically obtained by experimental measurement method, so as to adjust the running state of the fan in time.

In addition, during the design and installation of the blow-drying water removal equipment, it is necessary to pay attention to the spray angles of the two air knife nozzles. Because of the site constraints, an air knife driven by the same fan was installed on both sides of the bottle line. In order to increase the efficiency of blow drying, the air knives on both sides cannot be blown in pairs. Because even if the airflow velocity of the air knife is high, stagnation points may be formed on the surface of the bottle and the effect is affected, and the ejected airflow will bounce back under the action of the opposite flow, resulting in a greater jet loss. .

In addition to the necessary considerations in designing the conveying line for the packaging bottle, the speed of the workpiece must be limited as necessary to ensure that the surface of the bottle is blown by the air knife, and of course the fan and air knife can also be added. To improve efficiency.

Aiming at the blow drying requirements of filling product bottles, a new type of efficient cold blow dry water removal equipment was designed in this paper. The calculation and analysis of the airflow in the structure of the blow-drying water removal equipment and the related issues in the operation of the equipment are discussed. In the actual design, due to the diversity of glass bottle types, the bottle conversion mechanism needs to be set when the glass bottle passes through a high-speed airflow field generated by the air knife; considering the barrier effect of the ordinary plate chain on airflow and the water droplets The role of rebound, the need for a dedicated chain, dwelling on space, this article is no longer elaborated. After designing the surface of the bottle-blasting water-removal equipment product after it was successfully put into production by Changsha Light Industry Machinery Co., Ltd., the relevant units showed that the equipment has high technological content, reasonable design, simple processing, low cost, and good drying effect. The industry has a very broad application prospects.