Ethylene - China Petroleum Chemical Equipment Network

Этилен

Core Equipment: Cracking Furnace: The "heart" of the ethylene unit, operating at 800–900°C. Main types: light oil furnace, ethane furnace, and millisecond furnace. Quench Heat Exchangers (TLX, SMX): Terminate side reactions, recover heat, and produce high-pressure steam for internal use in the unit. Cracked Gas Compressor: Multi-stage centrifugal type, boosting pressure to 3.0–4.0 MPa, accounting for a large share of energy consumption. Cold Box & Low-Temperature Distillation Towers: Achieve cryogenic temperatures of -100°C to -160°C, including demethanizer, ethylene distillation tower, and propylene distillation tower. Acid Gas Removal System: Includes two systems — amine scrubbing (MEA/DEA) and caustic scrubbing. Dryers and Selective Hydrogenation De-alkyne Reactors: Molecular sieve drying and selective removal of acetylene and methylacetylene.

Technology

Ethane Cracking: Highest yield and lowest cost Hydrogenated Tail Oil Cracking: Balanced production of ethylene, propylene and aromatics

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Product Introduction

Ethylene (C₂H₄) is the simplest unsaturated hydrocarbon and one of the most important basic raw materials in the global petrochemical industry. It is a colorless, flammable gas at room temperature and atmospheric pressure, with a slightly sweet odor. It is highly reactive due to its carbon‑carbon double bond, which enables it to participate in polymerization, oxidation, halogenation, alkylation and other key chemical reactions.

Ethylene is mainly produced through the steam cracking of hydrocarbons such as naphtha, ethane, propane and butane, which are derived from natural gas and petroleum refining. Modern large‑scale petrochemical complexes use high‑temperature cracking furnaces and separation systems to produce high‑purity ethylene efficiently and stably. Its production volume is often regarded as an important indicator reflecting a country’s petrochemical development level.

As the “mother of petrochemicals”, ethylene is the foundation for manufacturing a wide range of downstream products. Its largest application is in producing polyethylene (PE), including high‑density polyethylene (HDPE) and low‑density polyethylene (LDPE), which are widely used in films, pipes, packaging materials, containers and daily plastic products. Ethylene is also used to synthesize ethylene oxide, ethylene glycol, styrene, ethanol, synthetic rubber and various chemical intermediates. These materials are further applied in packaging, construction, automotive, textile, medical and electronic industries.

In addition to its industrial importance, ethylene also acts as a natural plant hormone, regulating fruit ripening, seed germination, flower opening and leaf abscission. This biological function is widely used in agricultural post‑harvest management to control the ripening process of fruits such as bananas, tomatoes and mangoes.

Safety is critical in ethylene production, storage and transportation. Ethylene is flammable and explosive, so strict safety measures, including leak detection, explosion‑proof equipment and standardized operating procedures, are required. With the development of the global chemical industry, ethylene production technology is moving toward large‑scale, intelligent, energy‑saving and low‑carbon directions to meet growing market demand while supporting sustainable development.

Types and Characteristics of Equipment

Type

At normal temperature and pressure: colorless, flammable gas with a slight sweet odor, slightly lighter than air.Boiling point: −103.7°C, melting point: −169.4°C. It polymerizes readily and exhibits extremely high chemical reactivity.

Features

Almost all important polymer materials start from ethylene.Extremely wide application: downstream covers plastics, rubber, fibers, solvents, coatings, pharmaceuticals and others.Flammable and explosive: requires low-temperature, high-pressure, closed storage and transportation.High purity requirement: polymerization-grade ethylene purity is usually ≥ 99.95%.

Этилен

Ethylene is a colorless, flammable gas and the most important basic chemical in petrochemical industry.

Этилен

It is the raw material for polyethylene, plastics, fibers and other chemical products.

Basic Principles and System Composition

Basic Working Principle

Basic Production Principle

The mainstream industrial process for ethylene production is hydrocarbon steam cracking. Core principle: Under conditions of high temperature, short residence time, low hydrocarbon partial pressure and dilution steam, feedstocks such as ethane, naphtha and hydrogenated tail oil are cracked into low-molecular-weight olefins via thermal cracking. The main product is ethylene, with by-products including propylene, butadiene and pyrolysis gasoline. Main reaction:C₂H₆ → C₂H₄ + H₂

Overall System Composition

Raw Material Pre-treatment System Desulfurization, dehydration and dearsenization of feedstock to prevent catalyst poisoning and equipment corrosion. Cracking System (Core) Consists of cracking furnaces and quench boilers to accomplish high-temperature cracking and rapid cooling. Quench and Fractionation System Lowers temperature and separates heavy oil, gasoline, water and other components from cracked gas. Cracked Gas Compression and Purification System Pressurization, removal of acid gases (CO₂, H₂S), drying and diolefin/alkyne removal. Cryogenic Separation System Based on differences in boiling points, rectification at ultra-low temperatures (below -100°C)separates products including ethylene, propylene, methane, hydrogen and C4 fractions.

Basic Principles and System Composition

Typical Process Flow

Raw Material Pre-treatment Raw material (ethane / naphtha) → desulfurization → dearsenization → dehydration → fed into cracking furnace High-Temperature Cracking Raw material + dilution steam → cracking at 800–900°C in cracking furnace → cracked gas Quenching High-temperature cracked gas → rapid cooling in quench boiler → termination of side reactions → generation of high-pressure steam Pre-fractionation Cooled cracked gas → fractionation tower → separation of cracked heavy oil and cracked gasoline Compression and Purification Cracked gas → multi-stage compression → CO₂ and H₂S removal by amine scrubbing / caustic scrubbing → molecular sieve drying → selective hydrogenation for alkyne removal Cryogenic Separation Cooled to low temperature → demethanizer for methane / hydrogen separationDeethanizer → ethylene distillation tower → polymerization-grade ethylene productMeanwhile, propylene, C4 fraction, cracked gasoline and other by-products are separated Product Storage and Transportation Ethylene → low-temperature storage tank (-104°C) / pressurized spherical tank → tanker / ocean-going vessel → downstream units