Thin or variable paste: compare the sample basis first
Check whether samples were measured at comparable concentration, temperature and test conditions. If the comparison is valid, review fruit condition, time after crushing, break response, screen selection and the concentrate outlet. A target refractometer reading alone does not explain the particle structure that contributes to consistency.
Change one identified operating variable at a time within the established process. A sudden texture change after maintenance also justifies checking the installed screen and its seating. Adding more heat or pushing concentration higher without locating the change can obscure the original problem.
Separate a feed problem from a machine restriction
Surging transfer, a low vessel level or interrupted conveyor feed can reduce output before the main process equipment reaches its operating limit. Compare upstream supply, receiving level and pump response over the same time interval. Check the process path and instrumentation before interpreting one nominal capacity number as the cause.
| Symptom | Observe together | Follow the evidence toward |
|---|---|---|
| Wet pulper residue and lower pulp output | Feed temperature, screen load, residue path and product rate | Changed feed, blocked or unsuitable screen, assembly or operating condition |
| Unstable buffer transfer | Vessel level, inlet supply, outlet demand and pump response | Supply mismatch, air entry, restriction or unsuitable operating point |
| Falling evaporation rate | Feed solids, product flow, vacuum, heating and cooling conditions | Changed duty, utility limitation, fouling or a process restriction |
| Foam or inconsistent retail fills | Mixing air, transfer stability, product temperature and nozzle behaviour | Entrained air, changing product condition or filling adjustment |
| Increasing thermal pressure drop | Flow, product viscosity, heat-transfer behaviour and run history | Changed product or accumulating restriction requiring the established response |
Use the run history when heating performance changes
A heat-transfer change can follow a different product concentration, viscosity, feed rate or utility condition. Compare those records with cleaning history and the pressure and temperature observations from the same circuit. Deposits are one possibility; a utility or flow change may produce a similar symptom.
Access, inspection and cleaning follow the equipment procedure and safe isolation requirements. An unexplained thermal alarm or uncertain process state should be handled through the plant’s product-control and restart procedure, rather than by bypassing an interlock to regain output.
Make a service record useful to the next person
Record the machine or line section, product, operating rate, time the symptom began, recent adjustments and the relevant readings. A photograph of the component location and its identification can help distinguish a hardware issue from a process setting. Keep the finished-product and reject observations with the operating record.
After the corrective work, compare the same measurements over a defined run. That establishes whether the condition has improved and gives the plant a better baseline for its next change of raw material, concentration or recipe.
Further detail
Questions about this equipment and process
Why can output fall while the machine is still running normally?
The limiting condition may be elsewhere: a weaker feed supply, changed concentration duty, unavailable utilities, a receiving tank level or a packing interruption. Compare the connected process over one time period before assigning the loss to a single machine.