This document describes the operation of indirect bath heaters (IDBH) and direct bath heaters (DBH) used in a refining process. The IDBH heats crude oil to maintain its flowability, keeping the bath temperature at 85°C and crude outlet at 43.2°C. The DBH further heats crude before processing to 90°C. Both units consist of a shell, firetubes, coils and have controls to regulate temperature, pressure, and fluid levels. Safety controls shut the units down if temperature, pressure, or flame conditions are not within set limits.

1. Indirect and Direct Bath Heaters
Raj Dewangan
Emp Id: 203481
Dept: PSS (STF)

2. Process Flow Diagram
HX-3
HX-2
HX-1
IDBH
Wet crude tank
DBH
EET
Dry crude
Tank
DCO inlet header
WCO inlet header
DCO outlet header
WCO outlet header
CoCP
CoDP
8’’
12’’
Out
to
CTF
NHK

3. Indirect bath heater
• IDBH is used to heat the crude to maintain its flowability
• Following properties need to be maintained:
• Bath temperature = 85 ℃
• Crude outlet temperature = 43.2 ℃
• Flow rate= 5000kLPD * 2 (capacity 6500*2)
• Inlet temperature (>29)
• Inlet pressure: 4 < P < 6.2 kg/cm2g
• IDBH consist
• shell
• Firetubes & chimney
• heater coils: 8 passes
• expansion tank: 120mm level
• burner

4. IDBH Schematic

5. IDBH P&ID

6. IDBH Control philosophy
1. Wet crude inlet temperature (TT5601 > 44 ℃)
2. High Bath temperature (TT 5603 > 85 ℃)
3. Expansion tank level (L < 120mm)
4. NG line pressure P>1.4kg or P<0.1kg
5. Flame failure
In above cases close SDV,SV and open XV (BH tripped manual reset required)

7. Crude Inlet and Outlet

8. Expansion tank

9. Bath temperature sensors

10. Chimney

11. Natural gas supply line

12. Safeties and limits
1. Heating medium temperature is below set point(H-44,L-29 )
• TT5603 & 5604 = 85 ℃
2. Water level is at normal condition
• LG 5602, LT 5601
3. Pressure Transmitter high and low set point is at healthy condition
• PT 5605
4. Stack temperature of chimney is below set point
5. No flame in fire tube
Unit can be operated only when all safeties are in good condition

13. Burner and BMS
Spark ignition (for
10sec)
Pilot SV open
Flame relay
energised
Flame sense by UV
Ignition transformer
cutoff
Flame relay de-
energised
SDV Open, main
burner on
Ignition transformer
cutoff
Burner trip,
Mannual reset
required
Flame stablished No Flame
safety check

14. IDBH Control philosophy
1. Wet crude inlet temperature (TT5601) (H-44,L-29 )
• T > 44 ℃ , close SDV 5601&2, (main burner off) no need to heat through IDBH
2. Bath temperature (TT 5603) (SP = 85)
• T = 82-86 ℃, TCV 5601 operate on High fire (82-84 ℃) or Low fire (85-86 ℃)
• T = 88 ℃, close SDV 5601&2 (main burner off)
• T= 90 ℃, close SDV, SV and open XV (BH tripped manual reset required)
3. Expansion tank level
• L >= 120mm, close FLV
• 100 mm < L < 120mm, open FLV
• L < 90mm, close SDV,SV and open XV (BH tripped manual reset required)
4. NG line pressure P>1.4kg or P<0.1kg
• P>1.4kg or P<0.1kg , close SDV,SV and open XV (BH tripped manual reset required)
5. Flame failure: close SDV,SV and open XV (BH tripped manual reset required)

15. Direct bath heater
• DBH is used to heat the crude before processing in EET, inlet of crude is from HX-1 and
outlet to EET
• Following properties need to be maintained:
• operating temperature = 90 ℃
• Operating pressure = 7kg/cm2g
• Crude inlet temperature = 55.5 ℃
• Flow rate= 2500kLPD * 4
• Interface level = 450mm
• IDBH consist of
• Shell : filled with crude
• Firetubes & chimney
• Burner assembly
• XV at crude inlet (5706),
crude outlet (5707)
water outlet (5703)
out
inlet
Ew outlet

16. out
inlet
Ew outlet
DBH Schematic

17. DBH P&ID

18. Crude Inlet and Outlet

19. Bath Temperature sensors and pressure guage

20. Level guages

21. Water Outlet

22. Gas outlet

23. DBH Control philosophy
1. Bath temperature (TT 5705) (SP = 90 )
• T = 82-86 ℃, TCV 5701 operate on High fire(T<87 ℃) or Low fire (T<89 ℃)
• T = 91-92 ℃, close SDV 5701&2 (main burner off)
• T>= 92.5 ℃, close SDV, SV and open XV (BH tripped manual reset required)
2. Bath heater level (LS 5701)
• L < 3500mm, close SDV,SV and open XV of NG line(BH tripped manual reset required), close
XV (5703/06/07)
3. Interface Level (ILT 5701/02 = 450mm)
• ILT 5701 L > 450mm, open LCV 5702 for EW outlet, low alarm at 300mm
• ILT 5702 L< 300mm, close XV 5703 for EW outlet
4. NG line pressure P>1.4kg or P<0.1kg
• P>1.4kg or P<0.1kg , close SDV,SV and open XV (BH tripped manual reset required)
5. Flame failure: close SDV,SV and open XV (BH tripped manual reset required)

24. Fire safety arrangements

25. Thank you