Hydromethanation Char Withdrawal Standpipe Design
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Solution Overview
Problem
The existing methods for removing char by-products from hydromethanation reactors are inefficient, leading to energy loss and increased capital and operating costs due to the need for additional equipment and cooling processes.
Innovation Solution
A process involving a char-withdrawal standpipe with a countercurrent stripping gas flow to remove the char by-product, which is then cooled and discharged at superatmospheric pressure, reducing energy losses and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional char removal methods are used, then char by-products can be removed from the hydromethanation reactor, but additional equipment and cooling processes are required leading to increased capital and operating costs
Solution Approach 1:
The patent combines the char removal function with the existing standpipe structure used for catalyst withdrawal. The standpipe serves dual purposes: withdrawing catalyst and removing char by-products, thereby eliminating the need for separate char removal equipment and reducing capital costs while simplifying the overall system configuration
Solution Approach 2:
The standpipe is designed to perform multiple functions: catalyst withdrawal, char removal, and stripping gas injection. This multi-functional approach eliminates the need for dedicated char removal equipment, reducing both capital expenditure and operational complexity
2Loss of energy
If conventional char removal methods are used, then char by-products can be removed from the hydromethanation reactor, but cooling processes are required leading to increased energy loss
Solution Approach 1:
The patent converts the thermal energy in the hot char by-product into a beneficial resource. The hot char is used to preheat the stripping gas before it enters the reactor, and the cooled char is then utilized as fuel in the combustor to generate steam, thereby eliminating energy loss and creating additional process value
Solution Approach 2:
The patent changes the temperature parameter of the char by-product from a waste heat problem to a useful energy resource. By controlling the cooling process and utilizing the char at different temperature stages for different purposes (preheating stripping gas, then fueling the combustor), the system maximizes energy recovery and minimizes energy loss
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 process enhances the efficiency of char removal, reduces energy losses, and decreases capital and operating expenses by minimizing the need for additional equipment and cooling processes.
Implementation Method 1
feeding a stripping gas into the standpipe such that the stripping gas flows in a countercurrent direction to the flow of the stream of by-product char within the standpipe
Implementation Method 2
the stripping gas flows in a countercurrent direction to the flow of the stream of by-product char within the standpipe to generate (1) a stripped gas stream enriched in the entrained gas and (2) a gas-stripped char stream depleted in the entrained gas
Implementation Method 3
the gas-stripped char stream is cooled from a reactor temperature to a lower temperature
Implementation Method 4
the gas-stripped char stream is pressurized to a superatmospheric pressure
Data Source
AI summary
The present invention relates generally to processes for hydromethanating a carbonaceous feedstock in a hydromethanation reactor to a methane product stream and a char by-product, and more specifically to removal of the char by-product from the hydromethanation reactor.