Integrated Vertical Column for Spent Caustic Treatment

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Solution Overview

Problem

Existing methods for treating spent caustic streams in petroleum refining and petrochemical processes are capital intensive and require multiple equipment vessels, making them costly and space-consuming due to high pH and biochemical, chemical, and organic content incompatibilities with biological wastewater treatment plants.

Innovation Solution

A single vertical column apparatus divided into a mixing zone, a settling zone, and a mass transfer zone, where spent caustic is neutralized with a strong acid, allowing for efficient separation and stripping of acid gases and organic components, minimizing equipment and space requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple separate process vessels are used for treating spent caustic streams, then the treatment process can be completed, but the capital cost and real estate footprint increase significantly

Engineering Contradiction:

Improvetreatment process completionVSAvoidreal estate footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines multiple separate treatment processes (neutralization, settling, and mass transfer/stripping) into a single integrated vertical column apparatus. The column contains distinct zones for each function: a mixing zone for neutralization, a settling zone for phase separation, and a mass transfer zone for acid gas stripping. This merging eliminates the need for multiple separate vessels and interconnected piping, thereby reducing capital costs and real estate footprint while maintaining complete treatment functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single vertical column apparatus performs multiple functions simultaneously: it neutralizes spent caustic with acid injection, separates the resulting mixture into organic and aqueous phases through settling, and strips acid gases from the aqueous phase through mass transfer with inert gas sparging. This multi-functional design allows one piece of equipment to replace what traditionally required several separate units, directly addressing the contradiction between process completeness and space requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple separate process vessels are used for treating spent caustic streams, then the treatment process can be completed, but the capital cost increases

Engineering Contradiction:

Improvetreatment process completionVSAvoidcapital cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If spent caustic is treated with strong acid neutralization, then the pH is adjusted for further treatment, but acid gases and organic components require separation

Engineering Contradiction:

ImprovepH adjustmentVSAvoidseparation requirements

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The vertical column is segmented into three distinct functional zones to handle the complexity of separation: (1) a mixing zone where acid and spent caustic are thoroughly mixed for neutralization, (2) a settling zone where the neutralized mixture separates into organic and aqueous phases based on density differences, and (3) a mass transfer zone where inert gas sparges through the aqueous phase to strip dissolved acid gases. This segmentation manages complexity by providing dedicated space for each separation function within a single integrated apparatus.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each zone within the column has locally optimized conditions and structures: the mixing zone has high turbulence and acid injection points for rapid neutralization; the settling zone has quiescent conditions and phase disengagement space for efficient separation; the mass transfer zone has inert gas sparger distribution and sufficient residence time for acid gas stripping. This local optimization of quality and conditions in each zone enables effective handling of separation requirements without excessive overall device complexity.

Inventive Principle:

Principle #3Local quality

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 capital and operating costs by integrating multiple processes into a single vessel, effectively treating spent caustic streams while minimizing environmental impact and operational complexity.

Implementation Method 1

a mixing zone, a settling zone and a mass transfer zone. A waste stream inlet is connected to the column for introduction of the waste stream, such as spent caustic, to the mixing zone where it is mixed with a neutralizing agent

Methodology Applied

Scientific EffectMixing: Stirring

Implementation Method 2

An organic stream outlet in liquid communication with the settling zone is needed to remove separated acid oils, such as naphthenic acids, DSO, cresylic acids, and entrained hydrocarbon

Methodology Applied

Scientific EffectSettling: Settling

Implementation Method 3

An inert gas inlet is in fluid communication with the mass transfer zone in order to strip out the bulk of acid gases present

Methodology Applied

Scientific EffectGas stripping: Sparging

Data Source

PatentUS8906230B2Apparatus for treating a waste stream

Publication Date: 2014.12.09 MERICHEM CO

AI summary

An integrated unit operations for the treatment of a waste stream, such as spent caustic, is provided in a single vertical vessel having at least three separate zones: a mixing, a settling, and a mass transfer zone.