Dump Tank Heating via Heated Treatment Gas
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Solution Overview
Problem
The existing polymerization reactor dumping process is inefficient in removing residual hydrocarbons from the dump tank, requiring extended times due to the polymer's insulating properties and risk of melting, which complicates the emptying process and prolongs shutdown activities.
Innovation Solution
A method involving transferring reactor contents to a dump tank, where a first heated treatment gas primarily composed of hydrocarbons is used to heat the polymer fluff, followed by a second stage of purging with nitrogen gas to recover non-product components, enhancing the removal process and reducing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a steam jacket is used to heat the polymer in the dump tank, then the polymer temperature increases to facilitate hydrocarbon removal, but the polymer melting risk increases and the heating efficiency is reduced due to polymer's insulating properties
Solution Approach 1:
The patent introduces an intermediary heating medium (heat transfer fluid circulating through internal coils) to transfer heat to the polymer, avoiding direct contact between the heating source and polymer. This intermediary system allows controlled heat transfer while preventing localized overheating and melting, resolving the contradiction between achieving sufficient temperature for hydrocarbon removal and preventing polymer damage.
Solution Approach 2:
The patent replaces the conventional steam jacket heating system with an internal coil heating system that circulates heat transfer fluid. This substitution enables more efficient and controlled heat transfer directly to the polymer bed, overcoming the polymer's insulating properties while maintaining temperature control to prevent melting.
2Loss of time
If conventional nitrogen-only purging is used to remove residual hydrocarbons, then the process is simple to operate, but the removal time exceeds 7 days which is unacceptable for shutdown activities
Solution Approach 1:
The patent fundamentally changes the operating parameters by introducing controlled heating to raise polymer temperature to 50-150°C during the purging process. This temperature increase dramatically accelerates hydrocarbon desorption and evaporation rates, reducing removal time from over 7 days to a practical duration, while the added heating system complexity is justified by the critical time reduction.
Solution Approach 2:
The patent applies preliminary heating action to the polymer bed before and during the purging process. By pre-heating the polymer to appropriate temperatures, the system prepares the polymer matrix for more effective hydrocarbon removal, accelerating the subsequent purging operation and reducing overall shutdown time.
3Productivity
If the dump tank is heated to accelerate hydrocarbon evaporation, then the removal speed increases, but the energy input requirement increases significantly
Solution Approach 1:
The patent utilizes phase transitions (evaporation) of residual hydrocarbons at elevated but controlled temperatures (50-150°C). By heating the polymer to these temperatures, hydrocarbons transition from liquid/sorbed state to vapor phase, enabling efficient removal. The temperature range is optimized to achieve sufficient evaporation rates while minimizing excessive energy input.
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
This approach significantly reduces the time required to remove non-product components from the dump tank, minimizing shutdown durations and reducing NOx emissions compared to conventional nitrogen-only purging methods.
Implementation Method 1
heating the solid polymer by introducing a first heated treatment gas comprising primarily one or more hydrocarbons into the dump tank
Implementation Method 2
reducing a pressure of the dump tank, whereby a flash gas comprising a first portion of the at least a portion of the liquid and gaseous non-product components is recovered from the dump tank
Data Source
AI summary
A method of operating a dump tank of a polymer production process by transferring all or a portion of a content of a polymerization reactor into the dump tank, wherein the reactor contents comprise solid polymer, and liquid and gaseous non-product components, and removing at least a portion of the liquid and gaseous non-product components from the dump tank by: reducing a pressure of the dump tank, subjecting the solid polymer to a first cleaning stage comprising heating the solid polymer by introducing a first heated treatment gas into the dump tank, and subjecting the solid polymer to a second cleaning stage comprising purging the solid polymer by introducing a second heated treatment gas into the dump tank.