The influence of feeding conditions on MVR evaporator system
1. Feeding rate
The heat transfer efficiency of MVR evaporator system is closely related to the feed rate. When the feed rate exceeds the design range of the system, it will directly affect the evaporation heat transfer coefficient, which will reduce the evaporation rate and discharge concentration.
In the case of a certain amount of evaporation, the evaporation effect will be reduced if the feed rate is too large, and the discharge concentration will also decrease. On the contrary, a low feed rate may lead to an abnormal increase in evaporation temperature, and even cause dry burning or coking phenomenon, and may also weaken the working efficiency of the steam compressor.
2. Feed concentration
The change of feed concentration will change the physical properties of the material, under normal circumstances, when the the feed concentration goes higher, the viscosity and boiling point of the feed liquid will increase, thus affecting the heat transfer coefficient. Even if the feed rate remains the same, the evaporation amount may be reduced due to concentration changes, and in serious cases, it will lead to crystallization of the material in the heat exchanger, resulting in equipment blockage or damage.
Feed temperature
The MVR evaporator is optimally fed at the bubble point to ensure maximum evaporation efficiency. If the feed temperature is too low, the evaporator needs to consume additional energy to preheat the material, thereby reducing the effective evaporation area and reducing the overall evaporation efficiency. For this reason, in the design, a preheating device is usually set before the raw material enters the MVR evaporator to ensure that the feed temperature meets the requirements.
3.Influence of steam compressor working condition on MVR system
As the core component of the evaporation system, the performance of the MVR steam compressor directly determines the overall efficiency of the system. The main parameters of the compressor, such as flow rate, inlet and outlet temperature, and current, will affect the operating state of the system.
According to the law of conservation of energy, the total work required by the compressor is equal to the enthalpy difference between the inlet and outlet of water vapor, and the power provided by the motor must meet this demand. The design should select the appropriate compressor type (such as centrifugal, Roots, etc.) according to the actual needs with reasonable motor specifications to ensure that the compressor operate under the best working conditions.
The change of compressor inlet temperature will lead to the increase or decrease of specific volume, which will affect the steam flow and outlet temperature. In addition, the frequency adjustment during the compressor start-up process will also affect the flow rate and temperature rise, so the balance between the parameters needs to be precisely controlled to ensure the stable operation of the compressor.
The importance of gas-liquid separator design
The gas-liquid separator is the key equipment to realize the separation of material and secondary steam in MVR evaporator system. Its design needs to consider factors such as evaporation, evaporation temperature, material viscosity and liquid level to ensure efficient vapor-liquid separation.
Inadequate separator size can lead to secondary steam entrainment of too much high-concentration material, increasing the risk of compressor corrosion and reducing condensate quality. Therefore, a reasonable separator design is essential to maintain the normal operation of the system, especially the application of the defroster, which can improve the separation efficiency without significantly increasing the cost.
4.The role of the forced circulation pump and its impact on the MVR system
A forced circulation pump, also called recirculation pump, plays an important role in transporting liquids in the MVR evaporator system. In particular, the selection of a forced circulation propeller pump is particularly important for processes involving crystal formation. Axial flow pumps are ideal for such applications because of their large flow, low head, and less damage to crystals in the solution.
The performance of the condensate pump should not be ignored either. If the condensate cannot be discharged in time, water will accumulate inside the evaporator, seriously affecting the heat transfer efficiency and eventually causing the entire system to stagnate. Therefore, ensuring good sealing of the pump and appropriate operating parameters is the basis for ensuring the efficient operation of the MVR system.
Other potential influencing factors
In addition to the above main factors, piping design, valve selection and installation location, and operational norms will also have an important impact on the operation of the MVR evaporation system. For example, improper pipeline layout may lead to increased pressure loss and affect material flow; improper valve selection or unreasonable installation may cause leakage or other safety hazards.
In summary, although the technical principle of MVR evaporatior system is mature, as a complex system engineering, every link from design to installation and commissioning needs to be carefully planned and strictly controlled. Fully understanding the characteristics of raw materials, fine-tuning process parameters, rationally selecting equipment models and strictly implementing operating procedures are the keys to ensure the long-term and stable operation of MVR evaporatior system.
