Horizontal Gasifier Cooling and Slag Handling
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Solution Overview
Problem
The Fischer-Tropsch process for converting solid carbonaceous feedstocks into liquid hydrocarbons is complicated by the need for extensive measures to prevent fouling on heat exchanging surfaces, particularly when processing high alkaline feedstocks, and existing gasification reactors have complex designs due to separate outlets for slag and synthesis gas.
Innovation Solution
A process involving partial oxidation of the carbonaceous feedstock in a horizontal burner to produce hot synthesis gas and liquid slag, followed by direct cooling with liquid water, water scrubbing, water shift reaction, and purification to obtain a Fischer-Tropsch synthesis gas suitable for producing paraffinic hydrocarbons, simplifying the process and reducing fouling risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat exchanging surfaces are used in syngas cooling, then synthesis gas can be cooled effectively, but device complexity increases and fouling vulnerability increases
Solution Approach 1:
The patent removes the heat exchanger component entirely from the system. Instead of cooling syngas through heat exchanging surfaces, the invention uses direct water injection into the gas stream, extracting the cooling function from complex equipment and implementing it through a simpler direct contact method.
Solution Approach 2:
Water serves as an intermediary cooling medium that is injected directly into the syngas stream. This intermediary substance transfers heat from the gas without requiring heat exchanger surfaces, thereby simplifying the device while maintaining effective cooling.
2Temperature
If heat exchanging surfaces are used in syngas cooling, then synthesis gas can be cooled effectively, but fouling resistance decreases
Solution Approach 1:
The patent eliminates heat exchanger surfaces that are prone to fouling by using direct water injection. This removes the harmful interface where fouling occurs, while still achieving effective cooling through the water-gas contact.
Solution Approach 2:
The invention converts the potential harm of water condensation and fouling into a benefit by using water injection to cool the gas. The water that would otherwise cause fouling issues is instead used as the cooling medium itself, and the system is designed to handle high alkaline feedstocks that would normally exacerbate fouling problems.
3Productivity
If separate outlets for slag and synthesis gas are used, then large capacities per reactor are achievable, but device complexity increases
Solution Approach 1:
The patent combines the slag outlet and synthesis gas outlet into a single outlet location at the lower end of the reactor. This merging of outlets simplifies the reactor configuration while maintaining the ability to achieve large capacities through the vertical flow arrangement where slag flows downward and gas flows upward.
4Object-affected harmful factors
If extensive measures like rapping are implemented, then deposits are prevented from accumulating, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent removes the heat exchanger surfaces that require rapping maintenance. By using direct water injection cooling, the system eliminates the surfaces where deposits would accumulate, thereby removing the need for complex rapping mechanisms while still preventing fouling issues.
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 simplifies the production of paraffinic hydrocarbons by directly cooling synthesis gas with liquid water, achieving sufficient water content for a water shift reaction and reducing capital costs by minimizing the need for additional steam, while effectively handling high alkaline feedstocks and reducing fouling.
Implementation Method 1
performing a partial oxidation of the carbonaceous feedstock in said burner to obtain a stream of hot synthesis gas
Implementation Method 2
cooling the hot synthesis gas by directly contacting the gas with liquid water
Implementation Method 3
separating solids from the cooled synthesis gas by means of a water scrubbing process step
Implementation Method 4
performing a water shift reaction on at least part of the scrubbed synthesis gas
Implementation Method 5
performing a Fischer-Tropsch synthesis using the purified synthesis gas of step (f) to obtain a synthesis product comprising paraffinic hydrocarbons
Data Source
AI summary
A process to prepare a paraffinic hydrocarbon from a solid carbonaceous feedstock, preferably coal by performing the following steps,(a) feeding an oxygen comprising gas and the carbonaceous feedstock to a burner positioned horizontal and firing into a reactor vessel,(b) performing a partial oxidation of the carbonaceous feedstock in said burner to obtain a stream of hot synthesis gas which flows upwardly relative to the burner and a liquid slag which flows downwardly relative to the burner,(c) cooling the hot synthesis gas by first cooling the gas to a temperature of between 500 and 900° C. by injecting a gaseous or liquid cooling medium into the synthesis gas and subsequently second cooling the gas in to below 500° C. by directly contacting with water,(d) separating solids from the cooled synthesis gas by means of a water scrubbing process step,(e) performing a water shift reaction on at least part of the scrubbed synthesis gas,(f) separating sulphur compounds, carbon dioxide and other possible impurities from the shifted gas to obtain a purified synthesis gas, and(g) performing a Fischer-Tropsch synthesis using the purified synthesis gas of step (f) to obtain a synthesis product comprising paraffinic hydrocarbons.