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Design of a Thermal Cracking Process for Heavy Petroleum Feedstock

Содержание

Введение
Chapter 1. Theoretical Foundations of Thermal Cracking of Petroleum Residues
Chapter 2. Process Design Basis and Selection of Operating Conditions
Chapter 3. Equipment Design and Process Control
Chapter 4. Design Evaluation, Safety, and Environmental Performance
Заключение
Список литературы

Актуальность

Designing an effective visbreaking unit for petroleum residue is important for reducing the viscosity of heavy feedstocks, improving their processability, and evaluating the production of more valuable liquid products while managing energy use, coke formation, safety, and emissions.

Цель

To develop and evaluate a technically justified process design for visbreaking petroleum residue (tar), including its process scheme, operating basis, principal equipment, and key performance and safety considerations.

Задачи

Characterize tar as a visbreaking feedstock and explain the thermal-cracking reactions and process variants relevant to residue conversion.
Establish the design basis and justify the selection of operating conditions, process flow, material balance, and energy balance.
Identify the principal equipment and develop appropriate considerations for equipment design, instrumentation, control, materials, and fouling management.
Assess expected product yield and quality using relevant published or experimental data.
Evaluate the proposed design’s technical and economic feasibility, process safety requirements, and environmental impacts.

Введение

Thermal cracking can lower the viscosity of petroleum residue and convert part of it into lighter products, but greater conversion also promotes condensation, sediment formation, and coke deposition. This creates a design trade-off: operating conditions must deliver useful viscosity reduction without compromising product stability or equipment reliability. For a unit treating tar, the trade-off depends on the feed’s composition and physical properties as well as on the arrangement of the cracking and separation equipment. Establishing a sound design therefore requires connecting reaction chemistry to operating choices, equipment constraints, and product requirements.

The study aims to develop a design basis for a thermal cracking process that treats heavy petroleum feedstock through visbreaking. It seeks to characterize the feed and explain the reactions and process configurations relevant to residue conversion; to establish criteria for selecting temperature, pressure, and residence time; and to develop the process scheme and material and energy balance framework. It also aims to assess equipment and control requirements, product quality, safety and environmental measures, and the information needed to judge technical and economic feasibility.

The object of the study is thermal cracking of heavy petroleum residue in a visbreaking process. The subject comprises the relationships among feed properties, reaction conditions, process configuration, product yields and quality, and the design requirements for equipment, control, safety, and environmental performance.

The discussion links tar’s density, viscosity, and asphaltene content with its behavior during cracking. Bond cleavage produces lighter hydrocarbons, while competing condensation reactions can generate coke and unstable products. These pathways frame the comparison of coil and soaker configurations and clarify why viscosity reduction, conversion, sediment formation, and product stability must be evaluated together rather than as separate design targets.

The design basis brings those constraints into a proposed process flow, from feed heating and furnace cracking through soaking, quenching, fractionation, and product recovery. The analysis identifies the feed, intermediate, and product streams needed for material and energy balances, and considers how reaction severity, heat duties, and heat recovery shape operating conditions. Equipment design and process monitoring connect these calculations to practical limits such as residence time, pressure drop, tube fouling, and coke deposition.

The proposed design is assessed against product yield and quality objectives, with comparisons relying on suitable published or experimental data rather than unverified estimates. The evaluation also considers hazards associated with heavy-oil handling, high-temperature and pressurized service, furnace operation, and flammable products. Emissions, wastewater, and oily or solid wastes inform the environmental assessment, while equipment demands, energy consumption, product value, and operating constraints provide the basis for evaluating feasibility.

Глава 1. Theoretical Foundations of Thermal Cracking of Petroleum Residues

1.1. Composition and Properties of Petroleum Residue (Tar)

This section discusses the origin, chemical composition, and principal physical properties of tar as a heavy petroleum feedstock. It identifies the feed characteristics—such as density, viscosity, and asphaltene content—that influence its suitability for visbreaking.

1.2. Thermal Cracking Chemistry and Reaction Pathways

This section discusses the principal thermal reactions involved in residue cracking, including bond cleavage, formation of lighter hydrocarbons, and competing condensation and coke-forming reactions. It explains how feed composition and reaction severity affect product yields and quality.

1.3. Visbreaking: Purpose, Operating Principles, and Process Variants

This section discusses the role of visbreaking in reducing residue viscosity and improving the handling and value of petroleum products. It compares coil and soaker configurations in terms of their process arrangements, operating characteristics, and typical applications.

1.4. Product Formation and Quality Constraints

This section discusses the principal visbreaking products—gas, naphtha, gas oil, and cracked residue—and the quality requirements that constrain their production. It considers how conversion, viscosity reduction, stability, and sediment formation are related to process severity.

Глава 2. Process Design Basis and Selection of Operating Conditions

2.1. Design Basis and Feedstock Characterization

This section discusses the design basis for a visbreaking unit treating tar, including feed rate, feed properties, product requirements, and relevant design assumptions. It identifies the laboratory and reference data needed to establish a reliable material and energy balance.

2.2. Selection of Reaction Temperature, Pressure, and Residence Time

This section discusses how reaction temperature, pressure, and residence time determine conversion, viscosity reduction, and the risk of coke formation. It outlines the evidence and design criteria needed to select operating ranges appropriate to the specified tar.

2.3. Process Flow Scheme and Material Balance

This section discusses the proposed process flow from feed heating and furnace cracking through soaking, quenching, fractionation, and product recovery. It sets out the material-balance structure and identifies the feed, intermediate, and product streams for which values must be established.

2.4. Energy Balance and Heat-Recovery Opportunities

This section discusses the heat duties of feed preheating, furnace heating, reaction, quenching, and fractionation. It evaluates opportunities for heat integration using stream temperatures and duties obtained from design calculations or reliable process data.

Глава 3. Equipment Design and Process Control

3.1. Furnace and Soaking-Section Design

This section discusses the functions and design considerations of the visbreaker furnace and, where applicable, the soaker. It covers residence-time control, heat-transfer requirements, pressure drop, and measures to limit tube fouling and coke deposition.

3.2. Fractionation and Product Recovery Equipment

This section discusses the fractionator and associated equipment used to separate cracked vapors into gas, naphtha, gas oil, and residue streams. It addresses the process duties and separation requirements that inform equipment sizing and operating conditions.

3.3. Instrumentation, Control, and Process Monitoring

This section discusses the control variables and instrumentation needed to maintain stable visbreaking operation, including temperature, pressure, flow, and product-quality monitoring. It explains how control strategies help manage conversion, furnace firing, and the risk of unstable or off-specification products.

3.4. Materials, Corrosion, and Fouling Considerations

This section discusses material selection and degradation risks in high-temperature, heavy-oil service, including corrosion, erosion, fouling, and coke formation. It relates equipment protection and inspection needs to the process conditions and feed characteristics.

Глава 4. Design Evaluation, Safety, and Environmental Performance

4.1. Assessment of Product Yield and Quality

This section discusses how the proposed operating conditions affect product distribution, residue viscosity, and relevant product-quality indicators. It identifies comparable published or experimental data needed to assess whether the design meets its stated processing objectives.

4.2. Operating Risks and Process Safety Measures

This section discusses key hazards associated with tar handling, high-temperature cracking, pressurized equipment, furnace operation, and flammable products. It outlines suitable prevention, detection, and mitigation measures, including safeguards for abnormal operating conditions.

4.3. Environmental Impacts and Emission-Control Measures

This section discusses potential air emissions, wastewater, and solid or oily wastes associated with visbreaking and its supporting systems. It considers applicable control and treatment approaches and the regulatory or performance criteria used to evaluate them.

4.4. Technical and Economic Feasibility of the Proposed Design

This section discusses the design’s feasibility in relation to feed processing objectives, product value, energy consumption, equipment requirements, and operating constraints. It identifies the cost and performance data needed for a transparent evaluation without treating unverified estimates as established results.

Заключение

Заключение доступно в полной версии работы.

Список литературы