Cooler Wax Adhesion Prevention via Heavy Oil Recycle
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Solution Overview
Problem
In hydrocarbon production using a bubble column slurry bed reactor, wax adhesion to the cooler during unsteady operations, such as start-up or reduced reaction conversion rates, leads to cooling efficiency decline and potential blockages, which existing solutions fail to reliably prevent without impacting operation rates or increasing facility costs.
Innovation Solution
A hydrocarbon-producing apparatus and method that includes a vapor-liquid separator with multiple stages, where a filling material layer in the second vapor-liquid separation unit absorbs wax components, and a return line system that recycles heavy and light oil components to prevent wax adhesion on the cooler, maintaining operation efficiency and avoiding facility enlargement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reaction conversion rate is reduced or during standby operation, then the FT synthesis reaction stops or slows down, but wax adhesion to the cooler increases and cooling efficiency declines
Solution Approach 1:
The patent introduces a return line that circulates heavy oil from the vapor-liquid separation tank back to the cooler before wax accumulation occurs. This preliminary action of continuously circulating heavy oil prevents wax adhesion even when the reaction conversion rate is reduced or during standby operation, maintaining cooling efficiency without requiring high reaction rates.
Solution Approach 2:
Heavy oil acts as an intermediary substance that prevents wax adhesion to the cooler. The heavy oil circulates through the return line, coating the cooler surfaces and preventing wax crystals from adhering, thereby maintaining cooling efficiency during low-productivity periods without directly affecting the reaction process.
2Reliability
If a return line system is introduced to prevent wax adhesion, then cooling efficiency is maintained during unsteady operation, but device complexity increases
Solution Approach 1:
The heavy oil returned through the return line serves multiple functions: it cools the vapor-liquid separation tank, prevents wax adhesion to the cooler, and maintains fluid flow during unsteady operation. This multi-functionality reduces the need for separate systems, thereby limiting the increase in device complexity while maintaining cooling efficiency.
Solution Approach 2:
The patent recovers heavy oil from the vapor-liquid separation tank bottom and returns it to the cooler through the return line. This recovery and recycling of heavy oil prevents wax adhesion while utilizing existing process materials, avoiding the need for additional external systems and minimizing the increase in device complexity.
3Manufacturing precision
If the cooler outlet temperature is lowered to condense more hydrocarbons, then separation efficiency improves, but wax adhesion to the cooler increases
Solution Approach 1:
Heavy oil serves as a protective intermediary layer on the cooler surfaces. When the cooler outlet temperature is lowered to improve condensation efficiency, the heavy oil circulating through the return line prevents wax crystals from directly adhering to the cooler walls, allowing temperature reduction without proportional increase in wax adhesion.
Solution Approach 2:
The patent changes the temperature parameter of the heavy oil circulating through the return line to match or exceed the cooler outlet temperature. This parameter adjustment ensures that the heavy oil remains fluid and effective in preventing wax adhesion even when the cooler operates at low temperatures for optimal condensation, decoupling the two temperature requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents wax adhesion to the cooler, maintaining cooling efficiency and operation rates without increasing facility costs, even during prolonged standby or low reaction conversion rate conditions.
Implementation Method 1
a filling material layer in the second vapor-liquid separation unit absorbs wax components
Implementation Method 2
a vapor-liquid separator having a plurality of vapor-liquid separation units each including a cooler and a vapor-liquid separation tank, which is configured to cool hydrocarbons, which are extracted from a gaseous phase portion
Implementation Method 3
configured to liquefy a portion of the hydrocarbons in the vapor-liquid separation tank to perform vapor-liquid separation
Data Source
AI summary
In the hydrocarbon-producing apparatus, a vapor-liquid separation tank of a second vapor-liquid separation unit is provided with a filling material layer. A vapor-liquid separation tank of the first vapor-liquid separation unit has a first return line. The vapor-liquid separation tank of the second vapor-liquid separation unit has a second return line. A light component of light oil discharged from a bottom of the vapor-liquid separation tank is returned to a portion between a top side above a return-location from the second return line within the vapor-liquid separation tank of the second vapor-liquid separation unit, and a line directly connected with a cooler installed on the first vapor-liquid separation unit through the first return line. A heavy component of light oil discharged from a bottom of the vapor-liquid separation tank of the second vapor-liquid separation unit is returned to the filling material layer through the second return line.