---
title: "Case study: processing plants and improvement"
subject: "Instrumentation II"
chapter: 10
key: "semester_5/instrumentation_ii:cs-processing-plants"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/cs-processing-plants
site: BCT Engineering
---

# Case study: processing plants and improvement

Instrumentation II · Chapter 10: Case Study

- Asked in: 2074 Chaitra; 2069 Chaitra, 9 marks (asked 2 times)
- Video: [Case Study Instrumentation II (Uncut Video just for help)](https://www.youtube.com/watch?v=YXfgNRoyonM) — IOE Syllabus
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/cs-processing-plants
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-10

## Question

Describe the different processing plants that you have studied in case study. With neat and clean block diagram explain how the further improvement of these plants can be made.

## Short answer

Studied plants: reception/chilling, HTST pasteurisation, homogenisation/storage, filling and utilities. Improvement: automate with distributed microcontroller/PLC nodes linked via RS-485 to a central SCADA PC, each node controlling sensors and actuators. This provides consistent quality, reduced losses, lower manpower, traceability and predictive maintenance.

## Answer

**Assumed case study:** a milk pasteurisation and packaging section of a dairy plant (HTST process: raw milk tank, heat exchanger, steam-heated holding tube, cooling, filling). The existing system uses analog panel indicators, bimetal thermostats, a manual steam valve and operator logging. (If your own visit was to another plant, replace the process names; the structure of the answer stays the same.)

#### Processing plants studied (in the milk plant)
1. **Reception and chilling section:** milk is received in cans/tankers, weighed, tested (fat, SNF, acidity), filtered and chilled to below 5 C in a chiller.
2. **Pasteurisation plant:** HTST heat exchanger heats milk to 72 C for 15 s, then cools it to about 4 C. Steam from a boiler is used.
3. **Homogenisation and storage:** homogeniser and insulated storage tanks.
4. **Packaging (filling) plant:** pouch filling machine, date coding and crates.
5. **Utilities:** boiler, ice-bank/refrigeration, compressed air, effluent treatment.

#### Further improvement with block diagram
Automate the plant using distributed microcontroller/PLC nodes connected to a central supervisory computer:
```text
 Reception node --+
 Pasteuriser node-+--RS-485/Modbus--> Master PC (SCADA)
 Storage node ----+                    trend, alarm, report
 Filling node ----+
   each node: sensor -> ADC -> MCU -> relay/valve
```
- Pasteuriser: PT100, PID steam control, flow-diversion valve, data logger.
- Chilling and storage: temperature and level sensors with alarms and automatic agitator/pump control.
- Filling: weight/volume dosing with count and batch totals.
- Central SCADA: set-points, alarms, daily reports and energy monitoring; later link to ERP.
- Benefits: constant quality, lower losses, less manpower, traceability and predictive maintenance.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. HTST pasteurisation condition?
   A. 100 C for 1 h
   B. 40 C for 1 min
   C. 72 C for 15 s then cool to about 4 C
   D. 72 C for 15 min
   Answer: C. Standard HTST. (Key point: Pasteurisation)

2. Reception section chills milk to?
   A. Above 30 C
   B. 72 C
   C. 100 C
   D. Below 5 C
   Answer: D. Chilled to preserve. (Key point: Reception)

3. Improved architecture?
   A. Distributed nodes linked by RS-485/Modbus to a master SCADA PC
   B. Single manual panel
   C. Independent isolated machines
   D. Paper logs
   Answer: A. Central supervision. (Key point: Architecture)

4. Filling improvement?
   A. Manual guess
   B. Weight/volume dosing with count and batch totals
   C. No counting
   D. Visual check
   Answer: B. Automated dosing. (Key point: Filling)

## Related in Instrumentation II

- [Case study: current control and recommendation](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-existing-recommend-problems) — Instrumentation II, chapter 10, asked 3×
- [Case study: critical factors in process control](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-critical-factors) — Instrumentation II, chapter 10, asked 2×
- [Case study: revamping MBI system for CEO](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-ceo-revamp) — Instrumentation II, chapter 10
- [Case study: recommended changes and convincing](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-recommend-changes) — Instrumentation II, chapter 10, asked 2×
- [Case study: new system vs existing (cost, manpower)](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-cost-manpower-automation) — Instrumentation II, chapter 10, asked 4×
- [Case study: workflow, factors, proposed design, benefits](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-2076chaitra) — Instrumentation II, chapter 10

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