Nitrogen Removal in Hydrocarbon Pyrolysis Feed

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Solution Overview

Problem

The challenge in hydrocarbon pyrolysis, specifically steam cracking, is the management of nitrogen-containing compositions in feeds, which leads to catalyst poisoning, corrosion, and difficulties in producing light olefins with stringent purity specifications, due to the presence of nitrogen contaminants like ammonia and acetonitrile.

Innovation Solution

A method involving the separation of nitrogen-containing compositions from steam cracker effluent, including a process gas and pygas streams, followed by treatment through a compressor, condenser, amine tower, and caustic tower to produce purified light olefins, and the use of specific apparatus such as a steam cracker with integrated flash separation vessels and quench towers to manage nitrogen contaminants effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If nitrogen-containing compositions are present in steam cracker feed, then light olefin production can proceed, but catalyst poisoning and corrosion occur

Engineering Contradiction:

Improvelight olefin productionVSAvoidcatalyst performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by implementing a desulfurization and denitrogenation unit before the steam cracker. This unit removes nitrogen-containing compositions (such as ammonia and acetonitrile) and sulfur compounds from the feedstock prior to cracking, preventing catalyst poisoning and corrosion while maintaining light olefin production capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary processing unit (desulfurization and denitrogenation system) between the feedstock storage and the steam cracker. This intermediary system acts as a mediator that treats the feedstock to remove harmful nitrogen and sulfur compounds, allowing the main cracking process to proceed without direct exposure to poisoning agents

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If nitrogen-containing compositions are present in steam cracker feed, then light olefin production can proceed, but corrosion of system components occurs

Engineering Contradiction:

Improvelight olefin productionVSAvoidcorrosion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The desulfurization and denitrogenation unit performs preliminary treatment to remove nitrogen-containing compositions before they can cause corrosion. This preventive action eliminates ammonia and acetonitrile from the feed, preventing subsequent corrosion of steam cracker components while maintaining production continuity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potentially harmful nitrogen-containing compositions into removable contaminants through the desulfurization and denitrogenation process. By treating the feedstock beforehand, the system transforms what would be corrosive agents into separated waste streams, protecting equipment while maintaining productivity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If nitrogen-containing compositions are present in steam cracker feed, then light olefin production can proceed, but product purity specifications cannot be met

Engineering Contradiction:

Improvelight olefin productionVSAvoidproduct purity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The desulfurization and denitrogenation unit performs preliminary purification of the feedstock, removing nitrogen-containing compositions before cracking. This ensures that the resulting light olefin products meet stringent purity specifications while maintaining production rates

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts and removes nitrogen-containing compositions (ammonia, acetonitrile, and other nitrogen compounds) from the feedstock through the desulfurization and denitrogenation system. This extraction process eliminates the source of contamination, allowing production of high-purity light olefins that meet specification requirements

Inventive Principle:

Principle #2Taking out (Extraction)

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 effectively reduces nitrogen contaminants in light olefin streams, improving catalyst performance, reducing operational costs, and meeting stringent product specifications for light olefins.

Implementation Method 1

The hydrocarbon feed is cracked in a steam cracking furnace to produce a steam cracker effluent

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Implementation Method 2

A flash separation vessel can be used to separate a vapor phase and a liquid phase from the steam cracker effluent

Methodology Applied

Scientific EffectFlash separation: Flash Evaporation

Implementation Method 3

transferred through a compressor and a condenser and into a knockout drum

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS20230151283A1Hydrocarbon pyrolysis of feeds containing nitrogen

Publication Date: 2023.05.18 EXXONMOBIL CHEMICAL PATENTS INC

AI summary

The invention relates to hydrocarbon pyrolysis, e.g., the steam cracking of feeds comprising hydrocarbon and nitrogen-containing compositions. The invention also relates to equipment, systems, and apparatus useful for such pyrolysis, to the products and by-products of such pyrolysis, and to the further processing of such products and co-products, e.g., by polymerization.