I. Comprehensive Specification of Plant Design

1. Project Name: 10.8 m³ Vertical Test Furnace Control System
2. Project Scope: ⑴ Basic design of test furnace main body (to be completed by Party A); ⑵ Fabrication and installation of main plant assembly; ⑶ Installation of plant electrical control system and installation of industrial control software; ⑷ Installation of plant combustion system; ⑸ Installation of plant air‑supply, exhaust‑ventilation and flue‑gas exhausting systems; ⑹ Plant commissioning; ⑺ Operator training for Party A personnel and after‑sales service for the plant.

II. Design Scheme

1. Technical Parameters and Description of Test Plant ⑴ Test Specimens: Building components and their accessories, etc. ⑵ Net internal volume of plant: 10.8 m³ ⑶ Internal net dimensions: Width × Height × Depth = 3 m × 3 m × 1.2 m ⑷ External overall dimensions: Width × Height × Depth ≈ 6 m × 4 m × 2.1 m ⑸ Fuel Used: Natural gas ⑹ Operating Temperature: Design limit temperature 1300 °C; long‑term operating temperature 1200 °C; temperature rise shall follow the specified formula. ⑺ Surface temperature rise of plant: ≤ 60 °C ⑻ Temperature Measurement: 12 pieces of K‑type Ni‑Cr/Ni‑Si thermocouples (wire diameter: 0.75‑1.5 mm) inside the furnace chamber; 48 thermocouples on the rear face of specimens. Thermocouples shall be manufactured in compliance with BS 476‑Part 20:1987 / BS EN 1363‑1. ⑼ Pressure Measurement: 3 micro‑manometers with pressure sensors of ±100 Pa range and accuracy ±2 Pa; pressure‑sensing probes shall be manufactured complying with BS 476‑Part 20:1987 / BS EN 1363‑1. ⑽ Combustion Mode: 12 burners horizontally mounted on the rear wall (8 observation ports on rear wall). ⑾ Burner Power: 150 kW per burner on rear wall. ⑿ Control Mode: Fully‑automatic control of temperature and furnace pressure (automatic execution of standard time‑temperature curve and furnace‑pressure curve). ⒀ Others: Specimen trolley and furnace shell have been completed by Party A. ⒁ Software Design: Shall satisfy temperature, pressure and other reasonable requirements provided by Party A. ⒂ Total installed power: 65 kW ⒃ Total combustion power: 1800 kW for rear‑wall burners.
2. This design is valid for 3‑phase 4‑wire power supply system of 380 V / 50 Hz.
3. Fuel supplied by Buyer: Natural gas (calorific value 8500 Kcal/Nm³).

III. Main Steel Structure of Plant

Completed by Party A.

IV. Furnace Lining Works

Completed by Party A.

V. Furnace Pressure Control System

Flue gas inside the furnace is mechanically extracted by fan from furnace bottom. After air‑mixing and washing treatment, flue gas is discharged outdoors. The flue‑gas exhaust fan adopts frequency‑converter speed regulation to maintain furnace pressure within standard range. Stable furnace pressure is essential for proper execution of temperature curve. Three pressure measuring points are arranged inside furnace: one for control, two for display. ⑴ 3 pressure sensors of ±100 Pa range with ±2 Pa accuracy; six pressure tapping ports located at heights of 0.1 m, 0.5 m, 1.0 m, 1.5 m, 2.2 m and 3 m from furnace bottom. ⑵ Control Condition 1: Control at height 3.0 m from bottom: 15±5 Pa after 5 min; 17±2 Pa after 10 min; pressure gradient 8.5 Pa per metre; pressure at top shall not exceed 20 Pa. ⑶ Control Condition 2: Control at height 0.5 m from bottom: 0±2 Pa, [8.5H‑4.25]. ⑷ Control Condition 3: Control at height 1.0 m from bottom: 0±2 Pa, [8.5H‑8.5]. ⑸ Control Condition 4: Furnace top pressure: 20 Pa (0 /‑2 Pa tolerance). ⑹ Control Condition 5: User‑configurable set values.

VI. Furnace Combustion System

Pipeline natural gas is delivered to workshop. Gas supply pressure shall be below 0.2 MPa. Gas flows to main‑line pressure regulator of furnace to stabilize gas pressure within required range. A blow‑off valve is installed on main pipeline; when gas pressure exceeds threshold, gas will be automatically vented outdoors for safety protection.

1. Gas Safety System (from natural gas pipeline to furnace gas safety control assembly) ⑴ Control Valve: Flanged ball valve ⑵ Safety Valves: Blow‑off valve, solenoid valve ⑶ Pressure Regulator: Natural‑gas pressure regulating valve ⑷ Pressure Gauges: 0～0.5 MPa; 0～25 kPa
2. Gas Burners ⑴ Actuator: 3‑inch air‑damper actuator ⑵ Proportional Valve: 1‑inch gas proportional valve ⑶ Solenoid Valve: 2‑inch solenoid valve ⑷ Burner: 150 kW per rear‑wall burner ⑸ Valve: 2‑inch ball valve ⑹ Igniter: Automatic igniter with flame‑monitoring and remote‑ignition functions.

VII. Gas Burner Temperature‑Control System

1. This plant adopts one combustion system on rear wall. Each burner can operate independently and satisfy temperature‑rise requirements. ⑴ Rear‑wall burner layout: Twelve low‑flow flat‑flame burners are evenly distributed on furnace rear wall (3 columns in furnace width direction, 4 layers). Each burner corresponds to one temperature‑control point; thermocouples are mounted at matching rear‑wall positions. Burner output power is automatically adjusted according to temperature rise.
2. To meet furnace heating‑up and furnace‑pressure requirements specified by standards, both combustion‑air blower and flue‑gas exhaust fan adopt variable‑frequency control. This ensures actual heating curve closely matches standard time‑temperature curve and furnace pressure stays within test‑standard scope for optimal test performance. ⑴ Temperature‑control Condition 1: ISO 834 curve (corresponding formula implemented). ⑵ Temperature‑control Condition 2: Implement corresponding formula. ⑶ Temperature‑control Condition 3: Implement formula T= [relevant function]. ⑷ Temperature‑control Condition 4: 0＜t≤21, t＞21. ⑸ Temperature‑control Condition 5: 538 °C at 5 min; 704 °C at 10 min; 795 °C at 20 min; 843 °C at 30 min; 892 °C at 45 min; 927 °C at 1 h; 978 °C at 1.5 h; 1010 °C at 2 h. ⑹ Other temperature‑control conditions: Input directly by Party A within realizable range of the plant.

VIII. Thermocouple Installation Layout

1. Twelve temperature‑control thermocouples are installed at positions opposite respective burners.
2. Forty‑eight temperature‑measurement terminals are reserved for specimen unexposed‑face (back‑fire side), serving as test‑judgement basis. Thermocouples shall comply with BS 476‑Part 20 / BS EN 1363‑1.

IX. Plant Control Section

1. One combustion‑air blower (22 kW), one flue‑gas exhaust fan (30 kW), both variable‑frequency start‑up. One furnace‑pressure transmitter and one pressure controller adjust exhaust‑fan inverter frequency to achieve automatic furnace‑pressure regulation.
2. Nine K‑type thermocouples inside furnace chamber; eight temperature‑control loops in total. Thirty temperature‑wiring terminals for specimen unexposed face. Software displays and computes individual‑point temperatures and average temperatures.
3. One set of audible‑visual alarm system: alarms for fan trip, inverter trip, overtemperature, gas‑pressure over‑range, flame failure.
4. Interlock logic: After exhaust fan starts, combustion‑air blower starts with 5‑minute delay. Main gas solenoid valve can open only when gas pipeline pressure is between upper and lower limits. Power supply to automatic igniter is enabled only after main gas solenoid valve opens. After safety valve purges for several minutes, automatic igniter receives ignition command.
5. Main Functions of PC Control Software ⑴ Software launching: Open directly by double‑clicking shortcut icon. ⑵ New‑test entry interface: Specimen No., specimen name, test standard, customer name, project name, customer sample ID, sample arrival date, etc. Auto‑generate test serial number, test date and test start time. ⑶ Main running interface: Start / Stop / Auto‑run; test duration; standard furnace‑temperature curve with upper‑lower tolerance bands; actual average furnace‑temperature curve; temperature deviation; standard furnace‑temperature and tolerance; individual‑point actual furnace temperature & average value; unexposed‑face individual‑point temperature, average & maximum values; pressure readings at all measuring points. ⑷ Operation‑status interface: Display burner status, blower / exhaust‑fan running status; alarms for gas‑pressure over‑pressure / under‑pressure, flame loss and other faults. ⑸ Measurement interface: Display furnace‑temperature and pressure values at respective positions. ⑹ Curve Window 1: Furnace‑temperature vs time curve. ⑺ Curve Window 2: Unexposed‑face temperature vs time curve. ⑻ Curve Window 3: Pressure vs time curve. ⑼ Data‑sampling interval: Adjustable from 1 s to 30 s (default 5 s); interval error ≤ 0.1 s. ⑽ Test‑data storage: Export to Excel format, including general data sheet, furnace‑temperature sheet, furnace‑temperature curve sheet, furnace‑temperature deviation sheet, unexposed‑face temperature sheet, unexposed‑face‑temperature curve sheet, pressure‑curve sheet, minute‑by‑minute log sheet (standard temperature, furnace temperature, average furnace temperature, average unexposed‑face temperature, maximum unexposed‑face temperature, pressure data). Print function available. ⑾ Thermocouple break‑off detection: Software automatically identifies broken thermocouple; relevant burner follows curve‑set‑point; broken‑point value is excluded from average‑value calculation.
6. Industrial PC: Evoc brand; 21‑inch colour LCD monitor: Samsung brand; Printer: Canon brand.
7. Control software is self‑developed by our company, implementing fire‑resistance‑limit standard time‑temperature curves and other reasonable requirements from Party A.

X. Flue‑gas Exhaust System

1. Top‑exhaust flue‑gas extraction is adopted.
2. Two exhaust ports on furnace top. Flue gas converges into main duct, passes through counter‑current water‑spray washing, then discharged via exhaust fan.
3. Exhaust fan and flue‑gas ducts are made of 304 stainless‑steel. One set of flue‑gas recovery device is fitted above specimen frame.

XI. Plant Safety System

1. Automatic gas blow‑off upon excessive gas pressure with warning signal.
2. Alarm when main‑line gas pressure drops below 0.05 MPa to alert operator.
3. Main gas solenoid valve automatically closes upon fan trip.
4. Combustion‑air blower can only start 5 minutes after exhaust‑fan startup; main gas solenoid valve can only open after combustion‑air blower is running.
5. If any burner extinguishes during test, system shall NOT perform automatic re‑ignition; manual ignition is required together with audible‑visual alarm.
6. Alarm when exhaust‑fan temperature exceeds 250 °C.
7. Fans shall keep running until furnace internal temperature drops below 100 °C after test completion.
8. On‑site fire‑fighting facilities shall be equipped and regularly inspected by assigned personnel.

XII. Operating Procedures

1. Switch on workshop ventilation fan.
2. Open main‑pipeline gas control valve.
3. Power‑on PC and launch control software.
4. Open manual valves on gas main pipeline and branch pipelines.
5. Set on‑site igniter to remote‑ignition mode.
6. Close specimen door; start exhaust fan; start combustion‑air blower after 5 min; adjust furnace pressure to −10 Pa.
7. Open main gas solenoid valve.
8. Perform ignition: ignite one burner then proceed to next burner sequentially.
9. After all burners are ignited, fully close specimen door, click software to launch corresponding temperature‑curve automatic test.
10. Upon test completion, cut off gas supply; move out specimen trolley; rapidly seal furnace opening with temporary door, assign dedicated operator for monitoring. Do not shut down two fans until furnace temperature falls below 100 °C.