The Voith EcoHood encloses the dryer section in a special housing that still allows access for operation and maintenance with the highest level of safety.

Compared to open hoods or hoods with less insulation, very low heat and moisture get into the hall due to the superior insulation and modular design of the EcoHood. Thus, almost all of the vapor produced when drying paper can be utilized in the heat recovery system. The impacts on the climate in the hall are mitigated and the building is actively protected.

Dew point
On the one hand, a thorough capture of vapors is key to heat recovery for high energy efficiency in drying. On the other hand, the dew point of the hood is decisive, i.e., the possible moisture in the exhaust air due to the hood design. The higher the dew point, the less supply air and exhaust air is required, which also reduces power and steam consumption. Multi-stage heat recovery systems for heating of supply air, fresh and white water, as well as heating of the production hall, can often only be implemented and operated efficiently with a high dew point.

The EcoHood can be delivered in two versions, both suitable for new construction as well as for rebuilds.

EcoHood 62
The standard hood with an operating dew point of up to 62°C, for application in nearly all paper machines.

EcoHood 65
The hood with an operating dew point of up to 65°C for the highest energy savings. The amount of supply air and exhaust air can be reduced by almost 20%.

The dew point control system hood ventilation technology controls the supply and exhaust air quantities in the dryer section, thus reducing the amount of air and fresh steam required.

The dew point control system consists of sensors that measure the moisture in the hood exhaust air and a control algorithm that ideally tracks the supply and exhaust air quantities through speed control at the fans. Either constant exhaust air moisture is the basis for the control, or a stored product grade/air quantity matrix is used. This is advantageous for machines with a high portion of dirt in the hood exhaust air, since as a rule, exhaust air moisture sensors do not have sufficient measurement stability there.

By using the dew point control system, the power requirement at the ventilator drive is reduced. This reduced power requirement is achieved since the air quantity reduction of 30% reduces power requirements by more than 60% with speed control of the fans. Accordingly, the fresh steam requirement and the air leakage from the hood (exhaust air quantity minus supply air quantity) are also reduced. Heat recovery performance increases as well.

 

The dew point control system hood ventilation technology is used in the air system of the dryer section and reduces the quantities of air, saving steam and power in the overall process.

A holistic view of the process and optimal design of the heat recovery stages can achieve enormous savings.

In the case of a one-stage heat recovery system, only about 5-8% of the energy content of the hood exhaust air in the dryer section is used to heat the machine supply air. The rest just disappears through the roof. Voith retrofittable multi-stage heat recovery systems allow the energy from the hood exhaust air, but also that of other waste heat flows, e.g., vacuum pump waste air, to be used efficiently. As well as the machine supply air, the water for the process (fresh water, spray water, white water) and/or for heating the machine hall ventilation can therefore also be heated.

The hood and associated machine ventilation system form the core of every drying section. The dew point of the hood has a direct impact on the energy costs for drying. In addition, the dew point of the hood defines the potential for recovery of the energy used previously for drying the paper. High heat recovery rates can only be achieved if the hood dew points are high.

Voith offers you the right solution and perfectly matched systems for hood and machine ventilation technology – regardless of whether you install a new system or upgrade or expand your existing facilities:

• Hood supply and exhaust air systems
• Pocket/machine ventilation systems
• Provision of other machine-level systems (e.g., fabric cleaners, press tray heaters, stabilizers)
• Wet section exhaust systems with separators and spray systems
• Pulper exhaust systems
• Sizing press exhaust systems

The choice of system components in terms of design and material plus the configuration of the individual systems guarantee operational reliability, ease of access and long service life as well as simple, cost-effective maintenance and servicing.

Machine hall ventilation and air extraction systems ensure safe removal of heat and humidity from the paper mill. This creates a suitable production environment for the process and operating personnel and also actively protects the building.

Voith takes into account factors such as mill location, possible equipment positioning, optimum air distribution and air supply, and noise and fire protection, as well as cost-efficient energy supply, ease of operation and a maintenance program that incorporates a standardized spare parts inventory where possible.

Machine hall ventilation
Depending on application (new system/rebuild) and/or the area to be covered, various systems are available (displacement ventilation method, conventional ventilation using air grilles). Incoming air units are configured to suit the ambient conditions and installation options either as box, wall-mounted or large, free-standing units.

Ceiling ventilation systems
Ceiling ventilation systems avoid production disruptions resulting from condensation on the hall roof in wet areas. Tailored to the application at hand, we supply ceiling cross ventilation or heated forced ventilation false ceiling systems. Intelligent system configuration – with heat recovery as an option – ensures minimal running costs.

Machine hall air extraction
Our air extraction units in modular design can be installed on the roof or on an external wall. They feature good accessibility for maintenance and cleaning work plus an effective reduction in noise emissions. Voith offers special solutions for smoke extraction in the event of a fire.

The Voith EOS energy optimization system saves power and steam in new and existing plant ventilation systems, while the modular design allows gradual improvement of efficiency.

With the Voith EOS, the amounts of supply and exhaust air, as well as the consumption of hot water in a plant ventilation system, are adjusted exactly to the need and load. This saves steam and power, thereby lowering the primary energy requirement. In addition, the performance of integrated heat recovery systems is noticeably increased due to the improved control of temperature and water quantities, which further reduces consumption of fresh steam. In comparison to most existing systems that are controlled via an outside temperature matrix or heat curve, energy optimization with the Voith EOS can save several hundred thousand euros per year. Voith experts estimate the saving potential with a special simulation tool.

The Voith EOS can be used in new and existing plant ventilation systems.

The heating requirement for hall ventilation may be more than 10 MW/h depending on time of year, equipment location and size of paper mill. Voith's intelligent heating energy supply concepts allow effective use of all waste heat from the process and thus reduce the primary energy demand to a minimum.

Even existing facilities heated with steam or hot water can be optimized using simple means.

Control room cooling
Control room cooling systems remove waste heat and protect the switchgear from dust and corrosion.

Voith supplies system solutions from simple control room cooling with split cooling systems to control room cooling systems with ambient air-cooling equipment and positive pressure systems. A chemical air filter can be integrated to prevent corrosion.

For cooling purposes, complete cold water systems, including refrigeration with air or water-cooled refrigerating units or well water-cooling systems, are used.

Direct air conditioning of winders
Insufficient moisture in the area of the winder cutting blades can cause web shrinkage and tears, resulting in web breaks. Voith’s special air-conditioning systems prevent this problem and the ensuing production downtimes.

Air conditioning of finishing areas
Special air-conditioning systems to regulate a constant temperature and humidity in the room and/or around the production machine reduce the static charge in the paper in the finishing area (calender, winder, cross cutter) and thus ensure high productivity.

High pressure humidifiers or steam humidifiers are used for air humidification in compliance with the relevant hygiene standards.

Air-conditioning of operator stations, offices and staff amenities
A comfortable working environment is one of the prerequisites for efficient personnel. Voith designs and supplies ventilation and air extraction facilities with or without cooling for offices, staff amenities and control rooms, also in the form of split refrigeration systems.