Thin film evaporator is a type of evaporator, characterized by material flowing in a film like manner along the heating tube wall for heat transfer and evaporation. It has high heat transfer efficiency, fast evaporation speed, and short material residence time, making it suitable for the evaporation of heat sensitive substances. According to the reasons for film formation and flow direction, it can be divided into three types: rising film evaporator, falling film evaporator, and scraping film evaporator. Below are the steps, applications, and efficiency improvement measures for using thin film evaporators.
Steps for using a thin film evaporator
1. Preparation before driving
(1) General products have undergone water pressure testing and trial operation before leaving the factory, and the indicators meet the requirements.
(2) Start the motor and observe if the direction of operation is correct. It should rotate clockwise and not reverse.
(3) Measure whether the radial swing and axial string momentum of the shaft meet the requirements, and check whether the sealing is tightly sealed.
(4) Whether the oil level of the gearbox is in a normal state and whether the cooling water of the mechanical seal is kept unobstructed.
2. Normal driving
(1) Turn on the circulating cooling water pump and put the
Condenser in operation. Then open the concentrated solution container and vacuum the valve.
(2) Open the feed valve and pump in the feed liquid. Connect the power, start the motor, and observe if the direction of rotation of the motor is correct.
(3) Slowly open the steam valve and connect the steam trap, so that the steam pressure is around 0.15MPa.
(4) Observe the discharge of the evaporator and wait for the equipment to run stably for 5 minutes before sampling and analyzing the concentration of the concentrated solution. If the concentration does not meet the standard, make adjustments. When the liquid level of the concentrated solution container is about to be full, switch to another option and follow the steps to switch.
3. The sequence of normal parking is as follows: close the steam valve - close the feed valve - after the material is drained, close the discharge valve - flush the equipment - stop the motor - stop the circulating water pump and jet pump - open the vacuum breaking valve.
4. Safety precautions
(1) Do not start the motor for stirring when there is no liquid or when the liquid is full.
(2) The motor is strictly prohibited from running in reverse. During operation, do not touch the rotating parts with your hands.
(3) Do not press the button with wet hands to prevent electric shock.
The application of thin film evaporators
Thin film evaporators have the characteristics of high production efficiency, large production capacity, and short heating time of materials, and can be widely used for the concentration of dilute solutions of various chemical materials.
Scraper type thin film evaporator is an efficient evaporation and distillation equipment that mainly uses high rotation to distribute liquid into a uniform thin film for evaporation or distillation. At the same time, the scraper film evaporator can also be used for deodorization, defoaming reactions, heating, cooling and other unit operations. Currently, this device has been widely used in industries such as Chinese and Western pharmaceuticals, food, light industry, petroleum, chemical, environmental protection, etc. Especially, this equipment can be used to treat materials with high concentration, high viscosity, thermal sensitivity, and easy scaling characteristics.
How to improve the efficiency of thin film evaporators
1. Choose the appropriate working pressure and temperature: The operating efficiency of the evaporator is related to temperature and pressure, and it is necessary to choose the appropriate working pressure and temperature to ensure that the efficiency of the evaporator reaches its maximum.
2. Control of feed quantity and quality: The control of feed quantity and quality directly affects the operational efficiency of the evaporator. The operational efficiency of the evaporator should be improved by controlling the feed flow rate and quality.
3. Strengthen the cleaning of
Heat Exchangers: The heat exchanger of the evaporator may produce a large amount of scale during long-term operation, leading to a decrease in heat exchange efficiency. Regular cleaning of the heat exchanger should be carried out to ensure the heat exchange efficiency of the evaporator.
In addition, the following details can be optimized:
1. Reducing the operating speed of the scraper film evaporator steam compressor reduces the flow rate, avoiding the compressor from surging state. However, the outlet pressure of the steam compressor will also decrease accordingly, and adjustable blades can be used.
2. Check the connection parts of each component of the entire evaporator for any leaks, and replace the gaskets and other sealing components at the flange connection in a timely and regular manner.
3. Regularly clean the evaporator and choose a suitable cleaning cycle based on the scale formation in the
Evaporation System. If the scale formation in the
Evaporation system is severe, try to shorten the cleaning cycle as much as possible.
4. When the temperature of the cooling water in the evaporation system is too high, it can cause the steam to not condense in time and reduce the vacuum degree of the system. It is necessary to regularly supplement cold water to the circulating water pool to maintain a stable temperature of the cooling water.
5. The fouling and heat transfer efficiency of the condenser in the scraper film evaporator decreases, causing the steam to not condense in time and reducing the vacuum degree. Therefore, it is necessary to regularly inspect and clean the condenser.
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