Welded Pillow plate heat exchanger for falling film MVR evaporator system
MVR technology is to compress the secondary steam of the evaporator by mechanical method, increase its pressure and temperature, increase its enthalpy, and then send it back to the heating chamber of the evaporator to be used as heating steam, so as to keep the feed liquid in boiling state, while the heating steam itself condenses into water. Compared with the multi effect evaporation technology, MVR technology compresses and recycles all the secondary steam and recovers the latent heat, so it is more energy-saving than the multi effect evaporation technology.
Advantages of MVR Technology:
After start-up, there is no need for fresh steam, or a small amount of fresh steam is consumed, so the operation cost is low.
Simple structure, single effect operation, simplify the pipeline, instrument, electrical system.
Easy to start, simple operation, stable operation, less maintenance.
It occupies a small space and has few utilities. In general, there is no need for condenser and cooling tower.
The operation of the two evaporation processes for the treatment of wheat straw pulp black liquor is shown in the table.
Operation of two evaporation processes for treating paper pulp black liquor
|item||5 effect station||combined evaporation process|
|MVR pre concentration||5-effect evaporation station|
|Evaporation water (t/h)||100||64.28||35.72|
|RMB/T water evaporation capacity||45||25.93|
Note:In operation cost estimation:steam 150rmb/t,electricity 0.6 rmb/kWh,water 0.5rmb/t.
The investment of combined evaporation process equipment increased: evaporator (2500 m2) 375x10000 RMB; MVR compressor 400x10000rmb, total 775x10000 RMB
Annual operating cost reduction of combined evaporation process: 3672-2115 = 1557 (10000RMB)
Investment increase payback period of combined evaporation process: 755 ÷ 1557=0.5year
It can be seen that taking the scale of 100t / h as an example, the combined evaporation process can recover the increased investment in half a year, and save 1557 (10000 RMB) every year in the future, with considerable economic benefits.
Best possible energy efficiency
Compared to multiple-effect evaporators, MVR evaporators consume considerably less energy.
Low vapor velocities inside the evaporator, low shear rates, and the free flow falling film construction are advantages of the design in minimizing foam creation. This is especially important in MVR evaporators, not only to maximize the production of clean condensate, but also for protection of the compressor or fan.
Uniform liquor distribution of the liquor over the lamellas, and the continuous redistribution of the liquor created by the dimpled shape of the lamella surface, ensure a completely wetted heating surface and eliminate local scaling or over-concentration of liquor. The lamella heating surface ensures that water-soluble scaling can be washed away by a simple dilution wash, eliminating the need for time-consuming and costly outages for cleaning.
Highly efficient condensate segregation in the evaporator ducts and lamellas, plus the integrated stripping of foul condensate fractions, produce clean and re-usable water.
Working principle drawing