Two-Part Exchanger for Hydrogen PSA Water Removal
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Solution Overview
Problem
The existing hydrogen production processes face challenges in effectively controlling the inlet temperature of the desulfurization reactor and the outlet temperature of the synthesis gas condenser downstream of the autothermal reforming reactor, which affects the efficiency of desulfurization and water condensation, potentially damaging the Pressure Swing Adsorption (PSA) unit due to excessive water content.
Innovation Solution
A two-part exchanger is used upstream of the PSA unit, where the first part cools the synthesis gas using the desulfurized feed as a cold fluid, and the second part continues cooling to achieve total condensation of water at a temperature between 25°C and 35°C using cooled water, ensuring efficient heat transfer and preventing water damage to the PSA unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the synthesis gas is cooled using conventional exchangers, then the water condensation is achieved, but the PSA unit is damaged due to excessive water content
Solution Approach 1:
The cooling process is divided into two distinct sections: a first section that cools synthesis gas from high temperature to intermediate temperature, and a second section that cools from intermediate temperature to condensation temperature. This segmentation allows optimized heat transfer in each section and prevents water carryover to the PSA unit.
Solution Approach 2:
The invention introduces an intermediary cooling stage using process water at controlled temperature (25-35°C) between the high-temperature cooling stage and the final condensation stage. This intermediary stage acts as a buffer that prevents direct contact between hot synthesis gas and cold condensation surfaces, avoiding water vaporization and carryover.
2Reliability
If the inlet temperature of the desulfurization reactor is increased, then effective desulfurization is achieved, but the energy consumption increases
Solution Approach 1:
The invention merges the cooling of synthesis gas with the preheating of the feedstock for the desulfurization reactor in a heat exchange network. The heat released during synthesis gas cooling is captured and used to preheat the feed, reducing the energy required to reach the desulfurization temperature of 150-200°C.
Solution Approach 2:
The heat exchange system operates continuously to maintain the desulfurization reactor inlet temperature within the optimal range of 150-200°C. The continuous heat recovery and transfer ensure that energy is consistently utilized without interruption, maintaining both desulfurization efficiency and energy economy.
3Quantity of substance
If multiple exchangers are used in series for cooling, then the water condensation is improved, but the device complexity increases
Solution Approach 1:
The heat exchange system is designed to perform multiple functions simultaneously: cooling synthesis gas, condensing water vapor, preheating feedstock, and controlling temperatures for subsequent processing stages. This multi-functionality reduces the need for separate dedicated equipment, simplifying the overall device configuration while achieving effective water removal.
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 configuration ensures almost total recovery of water from the synthesis gas, maintaining the PSA unit's integrity and enhancing the overall hydrogen production process by ensuring proper desulfurization and condensation temperatures, thereby improving thermal efficiency and hydrogen yield.
Implementation Method 1
a first part which cools the synthesis gas by using the charge to be desulfurized as cold fluid
Implementation Method 2
a second part which continues the cooling until total condensation of the water contained in the synthesis gas at a temperature between 25°C and 35°C
Data Source
Figure 1
AI summary
The present invention describes a process for producing pure hydrogen by autothermal steam reforming of a hydrocarbon feed or ethanol containing sulfur products, a process in which upstream of the PSA purification unit is an exchanger allowing the total condensation of the water contained in the synthesis gas from the autothermal reforming reactor (ATR), said exchanger being made up of two parts: - a first part which cools the synthesis gas by using the feed to be desulfurized as the cold fluid, - a second part which continues to cool the synthesis gas until total condensation of the water contained in said synthesis gas.