A trio of upgrades—high‑efficiency vacuum systems, optimized press sections, and dryer exhaust heat recovery—is delivering double‑digit energy savings, multi‑MW power cuts, and steep CO₂ reductions on paper machines.
In papermaking, the biggest energy wins are hiding in plain sight: the vacuum boxes, the press nips, and the humid air billowing from the dryer hood. Vacuum systems alone can consume 20–25% of a tissue machine’s total power (evpvacuum.com). Each percentage point of dryness squeezed out in the press is worth about a 4% drop in dryer steam. And the dryer section—the single largest energy user on most machines—throws off recoverable heat that can be turned back into useful work.
The data from industry and academic case studies converge on the same conclusion: apply high‑efficiency vacuum pumps, optimize the press section to remove as much water as possible mechanically, and reclaim waste heat from dryer exhaust—then watch electricity and steam use fall by 30–50% per ton, often with fast paybacks.
High‑efficiency vacuum systems
Vacuum in papermaking (sub‑atmospheric pressure used to pull water from the sheet over forming and press elements) is essential—but often inefficient. Traditional liquid‑ring pumps (seal‑water based) run at roughly 30–50% efficiency. Replacing them with turbo blowers (dry vacuum pumps) and adding variable‑speed drives has cut vacuum energy by tens of percent in multiple mills. Runtech Systems’ “RunEco” retrofits, which pair high‑efficiency turbo blowers and tighter control of suction levels to actual water flows, report 30–70% reductions in vacuum power (paperadvance.com) (paper360.tappi.org).
In one retrofit case, modern turbo‑blowers saved ≈50% of vacuum energy—roughly 10 GWh/yr on a single machine (paperadvance.com). Audits routinely find oversized or misplaced pumps; across 14 machines, simply removing unnecessary vacuum boxes and fixing leaks freed up ~3.5 MW of power, according to an IIPIN industry study (iipinetwork.org). European mills have logged 20–45% reductions with “smart” vacuum systems (iipinetwork.org), and every megawatt saved translates into large CO₂ cuts—≈4,000 tCO₂ per year per 1.5 MW saved (paper360.tappi.org).
In practice, mills are installing efficient vacuum pumps—e.g., turbo blowers operating with ~80% motor efficiency—and using online dewatering flow meters to set only the vacuum needed, avoiding the ~40–60% idle capacity common in OEM vacuum systems (paperadvance.com). The result is hundreds of kW in electricity savings per machine and better runnability: vacuum applied only on critical picks and flatboxes, with less throttling and throttling losses (paperadvance.com) (paperadvance.com).
Press section optimization
Maximizing mechanical dewatering in the press section (the sequence of nips—contact zones between rolls—that squeeze water out before drying) directly cuts the dryer load. A rule‑of‑thumb on corrugated and paperboard machines: each 1 percentage‑point increase in sheet dryness after the press reduces dryer steam demand by ~4% (pressurescreenworld.com).
Extended‑nip “shoe” presses (presses that lengthen nip dwell time using a soft roll and belt) typically lift sheet solids by 2–5 points vs. conventional roll presses (ud-machine.com), cutting dryer energy use by up to ~15% (ud-machine.com) (iipinetwork.org). One liner‑paper case showed a 5‑point dryness gain after a shoe‑press retrofit, unlocking ≈20% more output on a dryer‑limited machine while saving steam (pulpandpapercanada.com).
Best practice combines multi‑nip (bi‑nip or tri‑nip) configurations, highly permeable felts (press fabrics that hold and transport water), and precise nip profiling with sensors for load and moisture to ensure uniform dewatering and avoid over‑pressing. IIPIN data indicate that installing a high‑energy shoe press (capex ~$38/ton capacity, ~$2.24/ton maintenance) can reduce drying energy by ~15% on tissue machines (iipinetwork.org). In combination, extended‑nip presses, double‑wide pockets, and well‑conditioned felts can push press solids from ~45–50% up toward ~55–60%, translating to multi‑GJ/ton savings in final drying energy.
For press‑section reliability and fabric life, mills commonly pair felt care with precise chemical dosing; where needed, an accurate chemical dosing unit can support consistent conditioning without asserting additional energy claims.
Heat recovery from the dryer
The dryer section often uses 50–70% of a machine’s energy. Dryer hoods and ventilated cylinders exhaust hot, moist air and condensate (“blow tank” steam) that can be captured with heat exchangers. State‑of‑the‑art systems condense the exhaust to recover latent heat (energy released on condensation) and preheat make‑up air. Industry studies estimate hood heat recovery can save on the order of 10–15% of thermal energy (iipinetwork.org).
In one fluting‑paper case, optimizing hood supply air temperature cut steam use by ~0.95 t/h (metric tons per hour)—roughly a 5.2% drop in overall drying energy—and improved dryer efficiency ≈4%, saving about $31k/yr and ~925 tCO₂/yr (jcarme.sru.ac.ir). Other mills deploy heat pumps on exposed exhaust for district heating in Nordic settings, and recover latent purge steam via steam‑impingement or condensing open‑wire dryers—capturing that purge heat can cut energy use by ~10–15% (iipinetwork.org).
Effective recovery hinges on airtight hoods, robust exchangers, and controls that handle variability. Incorporating heat‑recovery exchangers—with optional heat‑pump boosting—on dryer hoods can reclaim low‑grade heat at 30–50% thermal efficiency, yielding multi‑GJ/ton fuel savings and steep CO₂ cuts. Where recovered condensate is cycled to boilers, a condensate polisher (polishes steam condensate after heat exchange cooling) and related supporting water treatment equipment can help protect downstream systems without changing the energy balances cited above.
Indonesia policy context
Indonesia’s pulp & paper sector is tightening sustainability targets. Industry Regulation No. 11/2019 (“Green Industry Standard for Pulp and Paper”) mandates efficiency improvements in energy, water, and materials. The Ministry of Environment’s PROPER program rewards mills that exceed compliance with innovative sustainability measures to earn “Green” status (antaranews.com). Flagship mills like OKI have installed world‑class recovery boilers that recycle waste heat into power (andritz.com).
Energy audits under these programs often identify vacuum and dryer systems as low‑hanging fruit because of their multi‑megawatt savings potential. Achieving “Green Industry” targets will require Best Available Technologies—precisely the high‑efficiency vacuums, extended‑nip presses, and heat‑recovery systems outlined here—to remain competitive and compliant (mdpi.com) (antaranews.com).
Illustrative savings and payback
Combined measures can slash paper‑machine energy per ton by double‑digit percentages. For example, raising press dryness from 50% to 55% might save ~20% of dryer heat (1% dryness → ~4% dryer savings; roughly 4% × 5 = 20%) (pressurescreenworld.com). Coupled with a 30–50% cut in vacuum motor power (paperadvance.com) (paperadvance.com) and ~10% recovery of dryer waste heat (iipinetwork.org), total energy per ton could drop by ~30–50%.
A representative audit estimated $400k/yr savings across 14 machines (iipinetwork.org), and each MW of power saved avoided ~2,700 tCO₂/yr (based on local grid factors). Many mills report that these steps—vacuum optimization, press upgrades, and heat‑recovery—pay back in a few years and materially improve energy intensity.
Sources
Industry and academic case studies and reports (paperadvance.com) (paper360.tappi.org) (paperadvance.com) (pressurescreenworld.com) (ud-machine.com) (pulpandpapercanada.com) (iipinetwork.org) (iipinetwork.org) (jcarme.sru.ac.ir) (antaranews.com) provide energy and performance data on vacuum and press improvements and heat recovery. Indonesian context is drawn from Ministry and news summaries (legalcentric.com) (antaranews.com). All figures above are drawn from these literature sources, reflecting typical published outcomes.
