Natural Gas Liquids Stabilizer Column Operation Without Top Condenser
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Solution Overview
Problem
Small-scale LNG plants face inefficiencies and high equipment costs due to the need for top condensers in stabilizer columns, which require additional equipment and complexity, especially when dealing with high temperatures and heavy hydrocarbons like benzene.
Innovation Solution
Introducing a natural gas bypass stream upstream of the cold box and scrubber to an intermediate level of the stabilizer column, where it is cooled via Joule Thompson cooling, reducing the top temperature of the column without altering its performance and reducing reboiler duty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a top condenser is used in the stabilizer column, then the top temperature can be reduced and heavy hydrocarbons can be recovered, but the equipment complexity and cost increase
Solution Approach 1:
The invention extracts the condensation function from a separate top condenser device and integrates it into the stabilizer column itself by injecting cold natural gas at an intermediate level, eliminating the need for external condensation equipment while achieving the same temperature control and hydrocarbon recovery objectives
Solution Approach 2:
The injected natural gas stream serves multiple functions simultaneously: it acts as a cooling medium to reduce top temperature, provides reflux liquid through condensation of heavy hydrocarbons, and eliminates the need for separate condensation equipment, thereby achieving multi-functionality with a single intervention
2Quantity of substance
If a top condenser is installed, then heavy hydrocarbons can be recovered at the top, but additional equipment such as separator drum and pump are required
Solution Approach 1:
The invention merges the condensation process and the separation process into a single integrated operation within the stabilizer column. The cold natural gas injection causes heavy hydrocarbons to condense and fall directly to the bottom of the column where they are naturally separated from the gas phase, eliminating the need for separate condenser, separator drum, and pump equipment
3Device complexity
If the top temperature is reduced without a condenser, then equipment complexity is reduced, but the top vapor saturation temperature increases and requires additional equipment to handle condensed liquid
Solution Approach 1:
Instead of condensing vapors at the top and dealing with liquid removal, the invention inverts the approach by injecting cold gas at an intermediate level that travels upward, condenses heavy hydrocarbons along the way, and causes the condensed liquid to naturally fall downward to the bottom of the column where it is easily handled, thus eliminating the harmful effect of liquid accumulation at the top
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 lowers the top temperature of the stabilizer column from 60-80°C to 40°C, reduces reboiler duty by 6%, and eliminates the need for a top condenser, making the process more economically feasible and efficient.
Implementation Method 1
introducing a natural gas bypass stream that is upstream of the cold box and scrubber to an intermediate level of the stabilizer column. This gaseous stream is preferably letdown (and cooled via Joule Thompson cooling) prior to introduction to the stabilizer column
Implementation Method 2
wherein the natural gas naturally rises towards the top of the column and subsequently reduces the top temperature
Data Source
AI summary
A method for improved operation of a natural gas liquids stabilizer column, particularly a small-scale, is provided. The method can include the steps of: introducing a first feed stream comprising heavy hydrocarbons and natural gas to a stabilizer column to produce a top gas and a bottoms liquid, wherein the top gas has a higher concentration of natural gas as compared to the first feed stream, and the bottoms liquid has a higher concentration of heavy hydrocarbons as compared to the first feed stream; introducing a second feed stream into the stabilizer column, wherein the second feed stream has a higher concentration of natural gas as compared to the first feed stream, wherein the second feed stream is at a warmer temperature than the first feed stream when introduced into the stabilizer column, wherein the second feed stream is a gaseous stream; withdrawing the top gas from a top portion of the stabilizer column; withdrawing the bottoms liquid from a bottom portion of the stabilizer column; and sending at least a portion of the bottoms liquid to a liquid storage tank.