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We had a emergency shutdown in our DCU with no utilities. So, our heaters were plugged because we had not utilities to remove all the product inside the heaters coils. Our heaters do not have mule ear plug. We started the heaters with some burners and tried to remove the product inside the coils with steam but we did not have success, besides the heat from the burners. How can we remove the products inside the heaters coil ? Is there any equipment to clean up the heaters coils ?
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When the heater coils become plugged, about the only way to clear them is to cut some of the return bends off and hydro-blast the coil to remove the coke zthat was deposited.
If you have a process temperature a few rows back from the heater outlet, remove that thermowell and hydro-blast from there. If not, cut a return bend that is three or four rows up from the outlet and begin hydro-blasting from there. I was involved in using an inspection company to determine the extent of coke formation with some success.
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Rather than cutting all the ubends, you can drill some small holes every few ubends then do a pressure survey to determine which ubends to cut and hydroblast.
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I agree with Evan in that you do not have to cut off all the return bends. You need to find and clear the blockage. The hydro-blasters can clean around one or two return bends. Once you have an open path, you can decide to pig the rest of the coil to remove the remaining coke.
You may need to clean out the transfer line between the heater and the coke drums as they could have become blocked or restricted. -
We are studying with the heaters “cold” (no burners and pilot on) inject steam and with infrared device see any local hot or cold in order to detect the exact point where is the coke in the coil.
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I have tried the technique you described without success. At best it was inconclusive. We spent several days trying to get useful information that could have been spent hydro-blasting. You should set a time limit on investigating where the blockage is located so that you can get into corrective action.
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Now we are opening the transfer line between the heater and coke drum. We are concerned if the hydro-blaster can removes any oil inside the heater coils or any initial coke. Can hydro-blaster remove oil and any initial coke inside the heaters coil ?
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Typically, both hydrocarbons and coke are removed by hydro-blasting. If there is a large amount of liquid hydrocarbons in the heater or transfer lines, they will travel with the water and will put a large load on the wastewater treatment plant unless the effluent water from the hydro-blasting is collected for separate treatment.
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We opened the transfer line between heater and coke drum. We found the line all plugged with hard coke. Now we will open the heater coil and hydro-blastering the coils.
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