Reducing Pasteuriser Restart Downtime with Regeneration Bypass

CASE STUDY

Reducing Pasteuriser Restart Downtime with Regeneration Bypass

How a simple valve modification recovers lost production time during every start-up and diversion event

Executive Summary

Every dairy plant running a plate-type pasteuriser loses production time whenever the system starts up or diverts due to an out-of-spec temperature. Recovering back to pasteurisation temperature can take 10 to 15 minutes in a standard configuration, time in which the plant is running but not producing saleable output.

Goose Industrial Solutions evaluates and implements a Regeneration Bypass modification as part of pasteuriser upgrade and CIP integration projects. This case study explains the engineering principle behind it, the typical performance improvement plants can expect, and how it is implemented on existing pasteuriser skids without requiring equipment replacement.

The Problem: Why Restarts Take So Long

A standard plate-type pasteuriser uses Regeneration (REG) zones to recover heat from outgoing pasteurised milk and preheat incoming raw milk. This is efficient during steady-state production, but it creates a hidden cost during restarts.

When the system diverts (due to a temperature excursion) or starts up cold, the REG zones lose their thermal balance. Because REG zones typically account for roughly 80% of a pasteuriser's total plate surface area, bringing the holding coil back to the required 80 to 85°C means effectively reheating the majority of the plate pack, not just the heating section.

Figure 1: Regeneration zones make up the majority of plate surface area in a typical pasteuriser; this is why restarts take so long without a bypass.

The Solution: Regeneration Bypass

The fix is a mechanical and control logic modification, not a new pasteuriser. Two bypass valves are added to route raw milk directly to the heating section during start-up and diversion, skipping the REG zones entirely.

1. ● During start-up/diversion: bypass valves open, and milk goes straight to the Heating Zone. Only the heating and cooling sections (a small fraction of total plate area) need to reach setpoint.

   ● Once heating and cooling temperatures stabilise: bypass valves close automatically, and milk resumes its normal path through the REG zones for steady-state production.

   ● A non-return valve (NRV) prevents backflow, and raw milk continues to pass through the clarifier even during bypass, so product quality is not compromised.

Figure 2: Without bypass, milk recirculates through the full plate pack to restart (left). With bypass, REG zones are skipped entirely during restart (right).

Performance Impact

The core benefit is time, specifically the time between hitting 'start' or recovering from a diversion, and getting back into full production. Illustrative performance ranges typically observed:

Figure 3: Illustrative recovery time comparison, start-up and diversion events, with and without Regeneration Bypass.

Metric	Without Bypass	With Bypass
Start-up Recovery Time	~19 minutes	~8 minutes
Diversion Recovery Time	~20 minutes	~7 minutes
Plate Area Reheated on Restart	Full pack (~100%)	Heating + Cooling only (~20%)
Effective Capacity Impact	Baseline	+5% or more

Why This Matters for Plant Operators

4. ● Recovered production capacity: every minute saved on restart is a minute of actual production, without adding new equipment.

   ● Lower energy waste: reheating a smaller plate area on every restart reduces steam and hot water consumption over the life of the plant.

   ● Fewer product quality risk windows: shorter time spent in an unstable temperature zone during transitions.

   ● Low CAPEX: this is a valve and control-logic retrofit onto the existing pasteuriser skid, not a capital equipment replacement.

Figure 4: Estimated effective capacity gain from reduced restart/diversion downtime (illustrative).

Implementation Approach

At Goose, this modification is typically evaluated as part of a broader CIP and pasteuriser upgrade assessment. Implementation involves:

8. ● Reviewing the existing P&ID to identify optimal bypass valve placement (typically two control-type valves diverting from the balance tank/feed line to the heating section).

   ● Updating PLC/SCADA control logic to automatically open bypass valves on start-up/diversion, and close them once heating and cooling setpoints are confirmed stable.

   ● Validating temperature stabilisation logic against the plant's specific holding coil and REG zone configuration, as every pasteuriser skid is slightly different.

   ● Commissioning and trend validation to confirm recovery time improvement before handover.

Conclusion

Regeneration Bypass is a clear example of how targeted automation and mechanical intervention can unlock meaningful capacity gains without a capital equipment upgrade. For plants running frequent start-stop cycles or CIP-heavy schedules, this is often one of the highest-return modifications available on an existing pasteuriser line.

Goose Industrial Solutions evaluates this and similar automation-driven efficiency opportunities as part of our CIP system and pasteuriser upgrade engagements across India's dairy and food processing sector.

Goose Industrial Solutions Pvt. Ltd. | Authorised Siemens System Integrator

www.gooseindustrial.com