The heat exchanger is a common equipment in the paper and pulp mill. According to the working place, the heat exchanger has two functions. Firstly, the heat exchanger can be used to heat or cool the fluid to the temperature required by the pulping process. Secondly, the heat exchanger also recovers the heat to be reused in the pulp production, reducing the energy consumption.
Advantages of heat exchanger of CNBM
At present, the plate heat exchanger has widest application with various advantages.
- High heat transfer capability: it is generally 3-5 time of tubular heat exchanger.
- Small area occupied: the area occupied by the plate heat exchanger is greatly less than tubular type.
- Low scale coefficient: the plate type heat exchanger is less than that of tubular type.
- Light weight: the plate heat exchanger weighs on third of tubular type.
- Low price: the plate heat exchanger is 40%-60% cheaper than tubular heat exchanger.
- Easy to clean: the plate exchanger is easy to be disassembled, and the cleaning is more convenient.
- Small heat loss: the plate heat exchanger only expose the TEMP plate in the air, so the heat loss can be ignored, no need of insulation measure. But the tubular heat exchanger needs thermal insulation layer.
Working principle heat exchanger
The plate heat exchanger consists of a set of corrugated metal plates with holes for the passage of two liquids for heat exchange. The metal plate is mounted in a frame having a fixed plate and a movable platen on one side and clamped by clamping bolts. A gasket is placed on the plate to seal the fluid passages and alternately direct the fluid into the respective channels. The flow rate, physical properties, pressure drop and temperature difference of the fluid determine the number and size of the plates. The corrugated sheets not only increase the degree of turbulence, but also form a plurality of support points sufficient to withstand the pressure difference between the media. The metal plate and the movable compression plate are suspended on the upper guide rod and positioned by the lower guide rod, and the rod end is fixed on the support column, but if one of the liquid or two liquids passes through the heat exchanger instead of once, the interface should be opened on the fixed plate and the movable platen.
Heat exchanger selection guide
For some beginners, how to select heat exchanger will be the first question, CNBM has plenty of experience in heat exchanger manufacture, here is the comparison of tubular heat exchanger and plate heat exchanger.
According to the working principle, the tubular heat exchanger and plate heat exchanger all belong to the surface heat exchanger. The thermal medium and cold medium are fully insulated by the dividing wall, avoid the mixing of different medium thoroughly.
For heat exchanger, energy saving mainly depends on the heat exchange rate，we can analyze heat exchange rate from the structure of heat exchanger.
Plate heat exchanger: form the working principle, we know that the corrugated metal plates are used for the passage of two liquids. The corrugated metal plates of heat exchanger increase the turbulence of medium and heat exchange area, which is good for the heat exchange, so the plate heat exchanger has higher heat exchange efficiency. In general, the plate heat exchanger is usually more than 90%.
Tubular heat exchanger: the structure of tubular heat exchanger decides that its heat exchange efficiency is lower than that of plate heat exchanger.
Except for the factors mentioned above, there are some other factors should be taken into consideration, such as area occupied, requirements for medium, maintenance, requirements for temperature and press, etc.
Plate heat exchanger
- Compressed structure, small size, less area required;
- Higher requirements for medium, large-sized particles or fibers will block the channel;
- Higher requirement for temperature and press of medium.
Tubular heat exchanger
- Large size, more area occupied;
- Fewer requirements for medium, viscous medium, large-sized particles or long fibers are all available;
- Simple structure and less maintenance.
In conclusion, when you choose a heat exchanger, comprehensively consider all factors, find the best-combined point of environment protection and energy saving, and then the heat exchanger will help you realize the pulping process well.