Industrial mechanical vapour recompression MVR
A heat pump uses energy to transfer heat from a lower temperature
source to a higher temperature demand using additional energy. For
industrial heat pumps, the heat source is process waste heat.
Mechanical vapour recompression (MVR) is an open heat pump system
in which the pressure and temperature of the vapour, together with
the corresponding saturation temperature, are increased by means of
compression. Steam recompression is a specific variation of MVR.
Low-pressure steam exhaust from industrial operations, such as
evaporators or cookers, is usually vented to the atmosphere or
condensed in a cooling tower, while other plant operations on the
same site may require intermediate-pressure steam. Instead of
expanding high pressure steam across a throttling valve to meet
these needs, low-pressure waste steam can be mechanically
compressed to a higher pressure so that it can be reused. Steam
recompression relies upon a mechanical compressor to increase the
temperature of the latent heat in steam to render it usable for
process duties. The advantage lies in the fact that the required
compression energy is very small compared to the amount of latent
heat present in the recycled steam.
The energetic performance of steam recompression is expressed in
the coefficient of performance (COP). The COP gives the ratio of
the net recovered heat and the energy used by the compressor. In
this case, the net heat is the steam production including the
additional steam yield by water injection. Typical economical and
energy-efficient applications have a minimum COP of 3.5. Some
applications of MVR have a COP of 10 or even higher.
The key elements for a high COP are the following:
A low ratio of the absolute steam pressures. A guideline for the
maximum ratio is 6, but in daily practice the ratio is about 3.
A minimum capacity. A guideline is a minimum of one tonne of steam
per hour.Water injection after compression.
MVR evaporators minimize energy consumption
MVR evaporators (sometimes referred to as a Vapor Compression
Evaporator) removes water from mill liquors or effluents with
minimum energy consumption and maximum plant availability while
delivering high condensate quality.
The evaporators have lamella heating surfaces. Inherently
non-foaming, these evaporators are ideally suited for the low dry
solids applications of MVR evaporation with capacities from 10 to
200 t/h in a single unit.
MVR evaporators operate on a “heat pump” principle. The evaporated
water vapor is recompressed with a simple, low-speed centrifugal
fan or compressor which increases the saturation temperature of the
vapor. After the fan, vapor can be used as heating steam in the
same unit. The recompressed vapor condenses and releases its latent
heat through the heat transfer surface for further evaporation of
the liquor or effluent.
Equipment Structure
Double-effect forced circulation evaporator is composed of heater,
separator, vapor-liquid separator, condenser, vacuum pump, forced
circulation pump, discharging pump, condensate pump, electrical
cabinet, operation platform and all the pipe fittings, valves,
instruments and etc.
Heater: Two sets of vertical type tubular heater connect in series.
The feed liquid is pumped into the first heater by forced
circulation pump, then enters into the second heater. The heated
liquid flow downwards in tubes, and flow into separator by
tangential direction, better performance of vapor-liquid
separation.
Separator: Vertical type, the secondary steam is discharged from
the top, pass through a vapor-liquid separator before entering into
condenser. The bottom of separator is connected with a forced
circulation pump.
Vapor-liquid separator: Is used to prevent tiny liquid drops
produced during evaporation from escaping with secondary steam,
reducing loss of feed liquid and prevent pollution to pipeline and
cooling water.
Condenser: Condensate the huge secondary steam produced during
evaporation into liquid by cooling water, making concentration
carrying on smoothly. Meanwhile, separate non-condensable vapor
from secondary steam and cooling water, make it easily pumped out
by vacuum pump to guarantee vacuum degree.
Benefits
Very low specific energy consumption
No steam or cooling water required
Not necessary to integrate with existing evaporators
Location can be chosen relatively freely
Excellent condensate segregation
Easy capacity control
Proven in multiple applications in kraft and mechanical pulp mills
| Product Name | MVR Evaporator |
| Application | Waste Water Treatment |
| Condenser | Vertical |
| Warranty | 12 months |
| Features | Energy Saving/Low operation cost |
| Customized Service | Yes |
Working principle technical drawing
Production process
