PrimeDry hoods and air system
ANDRITZ PrimeDry hoods (PM, MG, impingement) and air systems improve the performance and economics of the drying process. The MG and impingement hoods increase drying capacity with the advantage of better moisture cross-profile as well as stretch profile (e.g. sack paper). The use of heat recovery systems reduces overall energy consumption. The hoods can be combined with ANDRITZ size and film presses.
PrimeDry PM hood
The ANDRITZ PrimeDry PM hood encloses the dryer section with insulated sheet plate elements down to the machine floor level. This basement closure prevents the cold air from entering the drying section and creates a virtually closed hot room inside the paper machine hall. The PM hood keeps heat losses in the dryer section low and avoids condensation within the drying section. As a result, temperature and humidity inside the entire machine hall are improved.
The hood and its auxiliaries (machine exhaust air and machine supply air) control the ventilation for the drying section with a uniform inflow of heated air in the vicinity of the paper web to quickly take up the water vapor produced. This water vapor is discharged with the exhaust air.
PrimeDry MG hood (for board and MG papers)
MG hoods can be arranged both on the upper and lower sides of the MG cylinder depending on the requirements. The hoods ensure uniform air distribution and impingement velocity across the sheet for highest drying rates and a good moisture profile. The constant distance between the nozzle and the paper or board enables optimum heat transfer. Drying temperatures go up to 400° C and impingement velocities up to 130 m/s.
PrimeDry IM hood
IM hoods can be arranged on both the upper and lower cylinder rows to boost the water evaporation rate. In unfelted dryers, the stretch profile will be improved (e.g. sack paper). The impingement velocity is adjustable by fan speed so that drying can be tuned to the paper qualities desired. The risk of overdrying the edges can be avoided with separate edge zones. Drying temperatures go up to 300° C and impingement velocities up to 120 m/s.
PrimeDry air handling systems for PM, MG, and IM hoods are separated from the machine hall ventilation. A heat recovery system can be employed to recover part of the heat from the machine exhaust air, which contains the entire heat energy required in the drying section. This recovered heat can be used for heating the machine supply air, circulation water for room ventilation, and process water.
At a glance
- Enhanced performance of the entire drying process
- Better moisture cross-profile as well as stretch profile
- Uniform inflow of heated air in the vicinity of the paper web
- Heat recovery for energy and cost savings