Heat Shield with Refractory-Free Lower Wall for Gasifier
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Solution Overview
Problem
Existing coal gasification plant skirt designs suffer from overheating damage due to the high-temperature, molten slag falling from the slag tap, which can lead to mechanical issues and inefficiencies in slag cooling and handling.
Innovation Solution
A gasification apparatus with a pressure shell, a slag bath containing quench fluid, and a heat shield with a membrane wall structure allowing passage of a cooling fluid, featuring a refractory-free lower wall part to protect the pressure shell from overheating, and a converging wall part with a slag discharge opening above the quench fluid, facilitating slag cooling and preventing refractory material spallation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a skirt is provided around the slag fall area to protect the pressure shell, then the pressure shell is protected from heat, but the skirt itself suffers from overheating damage due to the high-temperature molten slag
Solution Approach 1:
The heat shield acts as an intermediary component between the falling slag and the pressure shell. It is specifically designed with a refractory-free lower wall part that can withstand direct slag contact without suffering the same overheating damage as the full-skirt design, while still protecting the pressure shell from heat exposure.
Solution Approach 2:
The heat shield employs local quality by having different structural characteristics in different zones: the lower wall part is refractory-free to handle direct slag contact, while upper portions can have refractory lining for additional heat protection where needed. This localized differentiation allows the structure to withstand thermal exposure without uniform overheating damage.
2Temperature
If refractory material is used to line the heat shield for heat protection, then heat resistance is improved, but refractory material spallation occurs due to thermal shock from molten slag
Solution Approach 1:
The invention extracts the refractory material from the lower wall part of the heat shield that is directly exposed to molten slag. By removing the refractory lining in this critical zone, the design eliminates the thermal shock interface that causes spallation, while maintaining heat protection through the cooled metal structure and strategic refractory placement in upper areas.
3Device complexity
If a conventional skirt design is used, then slag cooling and handling is simplified, but overheating damage occurs leading to mechanical issues and inefficiencies
Solution Approach 1:
The heat shield serves as a specialized intermediary component that addresses the thermal protection need without requiring a full skirt design. This intermediate solution maintains relatively simple slag handling operations while eliminating the overheating damage that plagues conventional skirt designs, thereby improving reliability without excessive complexity.
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
The solution effectively minimizes overheating damage to the pressure shell and slag handling system, allowing for efficient slag cooling and reducing mechanical stresses, while maintaining operational efficiency and preventing refractory material spallation and blockages.
Implementation Method 1
the wall structure comprising an upper wall part and a lower wall part... for allowing passage of a cooling fluid
Implementation Method 2
allowing passage of a cooling fluid... to protect the pressure shell from overheating
Implementation Method 3
a slag bath located in a lower part of the pressure shell, the slag bath comprising a quench fluid
Implementation Method 4
where the slag is allowed to fall freely into a slag water bath where it can cool and solidify
Implementation Method 5
a free-fall trajectory for the slag, the free-fall trajectory extending downwardly between the slag discharge opening and the slag bath
Implementation Method 6
the slag is allowed to drip down along the wall surface, to a slag discharge opening or slag tap, where the slag is allowed to fall freely
Data Source
AI summary
The invention provides an apparatus for gasifying a fuel to form synthesis gas wherein also a slag is formed. The apparatus comprises:a pressure shell; a slag bath; a gasifier wall; a free-fall trajectory for slag; and a heat shield. The gasifier wall is arranged inside the pressure shell defining a gasification chamber. It comprises a converging wall part that is provided with a slag discharge opening, located above the quench fluid in the slag bath. The heat shield is arranged above the slag bath between the free-fall trajectory and the pressure shell. The heat shield has a wall structure for allowing passage of a cooling fluid, the wall structure comprising an upper wall part and a lower wall part. The lower wall part of the heat shield is essentially refractory free.