Heat tracing

[BZLAM21]

Dear Members
I am new pipeline designer Please help me on Benzene unloading pipeline design technologies ,I am also confused about steam tracing or electric tracing,
Project requirement : 4'' diameter pipeline / total = 4 km / delivery to storage tank.
Benzene Specification : Density = 884 kg/m3 / Viscosity = 0.5 cP / Operating temperature = 38 °C freezing point : 6 °C
Suction pressure = -0.1 bar g ; Discharge pressure = 8 bar g ; ;
Flow rate:20 m3
Vapour pressure: 0.03 bar abs
MDMT: 1°c
WIND SPEED : 12 m /s
MP steam : 12 barg and 210 °C
LP steam : 4.5 barg and 160 °C
Electrical power available
Question ??
a) What is the best way for benzene line heat tracing
b) How to calculate and determine if a 4'' diameter pipeline needed insulation or not?
c) How to flush and clean the benzene left inside the pipeline after loading is complete.
I don't know if it is enough to leave the pipeline with full Bnezene or clean it and the pipeline is empty and clean? What is the best solution?
Merci d’avance.

 

[LittleInch]

Steam tracing a 4km 4" line is nuts. A steam trace is OK in plants where you have short runs and a steam network with a condensate drain, but a 4km line is not suited to steam.

This isn't a free design service, but to start with,

a) Electric trace heating
b) yes you need insulation. Many on line calculators can help you. For a 4" line prob need 40 to 50mm PUF
c) normally you don't clear lines, but if you do then you don't need to trace heat so might be a good thing to do if you don't use it very often.

You could just blow it with Nitrogen or maybe diesel to flush it then pump benzene back.

Benzene is horrible stuff though. Be careful with it

 

[georgeverghese]

Self regulating type electric heat tracing is suitable for this application, more reliable than steam tracing, but check with heat tracing company re max permissible circuit length - you may need several circuits to cover 4km.

Use cellular or foam glass insulation if pipeline can be submerged in rain water.

In coastal application, chlorides from sea spray can accumulate in the insulation and accelerate surface corrosion - check with materials selection / piping painting experts on solutions.

Examination of the results in table 11-22 on page 11-72 of the 7th edn of Perry tell me 1inch insulation will do if minimum maintenance temp is 15degC with say outdoor min normal ambient temp at 1degC - note that min maintain temp flattens out at 150degF even at high energy cost of USD8/mmBtu - to be confirmed with detailed calcs

 

[pierreick]

Hi,
You did not give us much information about your layout. I guess your pipe will be installed on piperack ?
Why do you need to flush the line? is it a quality issue? where are you going to flush the line?
Where will be the metering station?
Where is your project located? Do you have access to cheap steam/electricity?
Do you have a backup position in case of utility failure (steam/electricity)?
Insulation material management is a big issue on a long distance, monitoring the insulation is key, subject to weather condition.
Same for steam traps. Less issue with electrical tracing .
If I was in your shoes I will contact company like Thermon and others to discuss electrical tracing .

Heat Trace Solutions for Industrial Applications | Thermon

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Note: missing information about outside temperature (air), this is a requirement to calculate the heat losses and outlet temperature of the benzene , without or with insulation.
Good luck,
Pierre

 

[LittleInch]

Also this lot - https://www.heat-trace.com/

Very knowledgeable.

 

[pierreick]

Hi,
the flow rate in a 4" pipe does not make much sense!
data must be consolidated.
more info better answer.
Pierre

 

[shvet]

a) depends on local conditions. if the pipeline is routed through a remote location then a heat tracing + telemetry is preferred.
b) if the pipeline should be heat traced then it should be insulated to avoid heat waste
c) a pig receiver&launcher

for intermittent service a pipeline can be untraced if it is preheated above freezing temperature prior to filling with a freezing liquid

we definitely need more info