Offgas stream direct contact condenser
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Solution Overview
Problem
The dehydrogenation offgas stream from styrene production contains organic compounds and steam that increase the duty on the offgas compressor, leading to higher energy consumption and potential polymerization of styrene at elevated temperatures, which can foul equipment.
Innovation Solution
A direct contact condenser is installed upstream of the offgas compressor to remove steam and organic compounds by contacting the offgas stream with a cooling medium, such as chilled water or a combination of water and ethylbenzene, allowing for the condensation of these components before they reach the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the offgas stream is compressed directly without prior condensation, then the compressor can maintain the required vacuum pressure, but the duty and energy consumption of the compressor increases significantly due to the presence of steam and organic compounds
Solution Approach 1:
A direct contact condenser is installed upstream of the offgas compressor to preliminarily condense and remove steam and organic compounds from the offgas stream before compression. This preliminary condensation action reduces the volume and mass of gas that the compressor must handle, thereby reducing compressor duty and energy consumption while maintaining the required vacuum pressure.
Solution Approach 2:
The direct contact condenser extracts and removes steam and organic compounds from the offgas stream by condensing them into liquid form. This extraction of harmful components before compression reduces the workload on the compressor and prevents potential polymerization issues in the compression system.
2Object-affected harmful factors
If the offgas stream is cooled to condense styrene, then polymerization and equipment fouling are prevented, but the presence of steam and organic compounds still increases compressor duty
Solution Approach 1:
The direct contact condenser merges the functions of cooling (to prevent styrene polymerization) and condensation (to remove steam and organic compounds) into a single unit. By combining these functions, the system simultaneously prevents polymerization and reduces compressor duty, as the condensed liquids are removed before the gas enters the compressor.
Solution Approach 2:
The direct contact condenser utilizes phase transition by condensing steam and organic compounds from vapor phase to liquid phase. This phase change allows for efficient removal of these components through liquid discharge, reducing the gas volume that requires compression and preventing styrene polymerization.
3Use of energy by moving object
If a direct contact condenser is installed upstream of the compressor, then steam and organic compounds are removed reducing compressor duty, but additional equipment and process complexity are introduced
Solution Approach 1:
The direct contact condenser utilizes hydraulic principles by injecting cooling water directly into the offgas stream to achieve condensation. This hydraulic approach is simpler than thermal conduction methods requiring heat exchange surfaces, as it uses direct liquid-gas contact for heat transfer and condensation, reducing equipment complexity while effectively removing steam and organic compounds.
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 solution reduces the duty on the compressor by removing a significant portion of organic compounds and steam, lowering the energy requirements and preventing styrene polymerization, thereby reducing equipment fouling and operational costs.
Implementation Method 1
contacting the offgas with a cooling medium; the condensation of organic compounds and steam contained within the offgas stream
Implementation Method 2
contacting the offgas stream with a quench stream prior to the offgas stream exiting the condenser
Data Source
AI summary
Methods and systems for the dehydrogenation of hydrocarbons include a direct contact condenser to remove compounds from an offgas process stream. The reduction of compounds can decrease duty on the offgas compressor by removing steam and aromatics from the offgas. The dehydrogenation reaction system can be applicable for reactions such as the dehydrogenation of ethylbenzene to produce styrene, the dehydrogenation of isoamiline to produce isoprene, or the dehydrogenation of n-pentene to produce piperylene.