Drying Hood Energy Control in Fibrous Web Manufacturing
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Solution Overview
Problem
The existing methods for controlling energy consumption in fibrous web manufacturing processes, particularly in paper and board making, are inefficient as they maximize humidity content without optimizing energy consumption, leading to high thermal and electric energy usage.
Innovation Solution
A method and arrangement that adjust the removal of humid exhaust air and feed dry replacement air to maintain humidity below a predetermined maximum value, using a sensor array to measure heated steam consumption and adjust exhaust air removal to minimize total heated steam consumption, and calculate a total energy value using impact factors for both heated steam and electric energy to optimize energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If humidity content of exhaust air is maximized to maintain zero pressure level in the hood, then the risk of air entering or exiting through web openings is minimized, but total energy consumption increases due to excessive heated steam usage
Solution Approach 1:
The invention changes the control parameter from maximizing humidity content to minimizing total energy consumption. The system dynamically adjusts exhaust air removal and replacement air heating based on real-time energy consumption measurements, transitioning from a humidity-based control strategy to an energy-based control strategy that optimizes the balance between pressure maintenance and energy efficiency
Solution Approach 2:
The invention implements a feedback control system that measures total energy consumption (heated steam for drying cylinders plus heated steam for replacement air heating) and uses this information to adjust exhaust air removal and replacement air flow rates. This closed-loop feedback enables the system to maintain zero pressure level while minimizing energy consumption by continuously adapting to changing conditions
2Stability of the object's composition
If replacement air is heated to temperature close to hood interior temperature to maintain constant conditions, then humidity control is improved, but heated steam consumption increases
Solution Approach 1:
The invention applies partial heating to replacement air, heating it to a temperature that provides sufficient stability for the hood atmosphere without over-heating to match the exact hood interior temperature. This partial action approach maintains adequate atmospheric stability while reducing the energy required for replacement air heating
Solution Approach 2:
The invention makes the replacement air heating temperature dynamic rather than static. The heating temperature and flow rate are continuously adjusted based on real-time measurements of total energy consumption and hood conditions, allowing the system to adapt the heating level to actual needs rather than maintaining a fixed high temperature
3Object-affected harmful factors
If exhaust air removal is increased to prevent condensation on hood structures, then condensation risk is reduced, but energy consumption increases due to loss of warm humid air
Solution Approach 1:
The invention maintains continuous monitoring and adjustment of exhaust air removal to keep the hood atmosphere just below the condensation point. By continuously adapting the exhaust flow rate based on real-time energy consumption measurements and humidity conditions, the system maintains the minimum necessary exhaust removal to prevent condensation while minimizing energy loss from excessive air removal
Solution Approach 2:
The invention replaces the conventional mechanical approach of fixed high exhaust air removal with a sensor-based control system that measures energy consumption and humidity to dynamically adjust exhaust flow. This substitution of mechanical fixed-flow systems with intelligent sensor-controlled systems enables precise control that prevents condensation while minimizing energy loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the total energy consumption by minimizing heated steam and electric energy usage, providing a cost-effective and versatile optimization of energy use in the drying section of paper or board making machines.
Implementation Method 1
the heat energy is transferred from the cylinder surface to the fibrous web, while the moisture in the web is evaporated
Implementation Method 2
heated steam may also be used to heat the replacement air to the correct temperature before it is fed inside the hood
Implementation Method 3
the moisture in the web is evaporated and the web is dried
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a method and arrangement for controlling energy consumption in a manufacturing process of a fibrous web, such as paper, board, tissue web or the like. Heated steam is consumed by heating of drying devices, which form at least one drying group inside a drying hood for removal of moisture from the fibrous web, and blowing devices remove humid exhaust air from the drying hood and feed dry heated replacement air into the drying hood. Heated steam is further consumed by heating of replacement air, gaseous process flow(s) and/or liquid process flow(s) to predetermined temperature ranges. The method comprises steps of: maintaining inside the drying hood an air humidity below a predetermined maximum humidity value; determining a total consumption of heated steam consumed by the drying devices and by heating of replacement air and/or the said process flow(s), and adjusting the removal of the humid exhaust air from the drying hood on a level where the total consumption of heated steam is minimised.