Tungsten Carbide Control Valve for Extreme Service
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Solution Overview
Problem
Control valves in extreme conditions, such as high-temperature and high-pressure hydrogenation processes, face issues like cavitation, erosion, and vibration due to erosive and corrosive media, leading to part destruction and difficulty in disassembly, especially with tungsten carbide parts expanding differently than steel components.
Innovation Solution
The valve piston and head are made in one piece of tungsten carbide, with a semicircular or cup-shaped design to reduce vibrations and evaporation, and additional pressure reduction levels with tungsten carbide balls or disc springs are used to minimize contact and gap formation, along with a protective metal wall and conical insert member to manage thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tungsten carbide parts are used in high-temperature control valves, then erosion and corrosion resistance is improved, but thermal expansion mismatch with steel components causes gaps and vibrations
Solution Approach 1:
The patent changes the material parameter by using solid tungsten carbide instead of conventional valve seats and heads. This material substitution provides superior erosion and corrosion resistance in high-temperature hydrogenation processes, while the design accepts and manages the thermal expansion mismatch through careful assembly and operation procedures
Solution Approach 2:
The tungsten carbide valve seat and head are designed as replaceable wear parts. When they become worn or stuck due to thermal expansion issues, they can be replaced without replacing the entire valve body, reducing long-term costs despite the high initial material cost
2Strength
If tungsten carbide valve head is welded to steel valve piston, then connection strength is improved, but welding difficulty and cost increase
Solution Approach 1:
The patent introduces a two-part ring made of stainless steel as an intermediary component between the tungsten carbide valve head and the steel valve piston. This intermediate connector facilitates the connection while managing the material incompatibility, though it increases assembly complexity
Solution Approach 2:
The valve piston and valve head are merged into a single integral component made entirely of tungsten carbide. This eliminates the welding interface between dissimilar materials, simplifying manufacturing while maintaining connection strength through the monolithic structure
3Ease of operation
If conical valve head hits against valve seat, then control function is improved, but vibration and part destruction increase
Solution Approach 1:
The patent modifies the valve head geometry from a conventional conical shape to a spherical or rounded contour. This curved surface provides better contact with the valve seat, distributing forces more evenly and reducing vibrations and erosive impacts during valve operation
4Productivity
If control valve operates at high pressure and temperature, then process control capability is improved, but cavitation and evaporation cause medium destruction
Solution Approach 1:
The patent changes the physical parameters of the control valve design, including pressure reduction levels and flow path geometry, to minimize cavitation and evaporation effects. The solid tungsten carbide materials resist the destructive effects of high-temperature medium decomposition
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 design reduces cavitation, erosion, and vibration, enhances durability, and simplifies maintenance by minimizing tungsten carbide part exposure to extreme conditions and facilitating easier disassembly, while maintaining effective control over medium flow.
Implementation Method 1
control valves are used in critical media with extreme conditions... whose components can then be separated into different levels... For this purpose, control valves are used in critical media with extreme conditions, e.g. in order to drain in high-pressure hot separators
Implementation Method 2
control valves are used in critical media with extreme conditions... The reaction between hydrogen and hydrocarbon takes place under high pressure and at high temperatures
Implementation Method 3
When the control valve is opened, strong flow forces occur, in such a way that the valve piston is exposed to vibrations. At the same time, parts of the valve piston and the valve head shake in the valve seat. In order to reduce these vibration effects, damping rings made of graphite were used in the outlet funnel... Steel expands considerably at this high temperature—however, tungsten carbide does not, since this material has a much smaller thermal expansion coefficient
Implementation Method 4
Evaporation inevitably takes place in the control valve, partly supercritical, since the pressure falls under the vapour pressure in each valve. This causes cavitation, erosion and vibration in the valves
Implementation Method 5
Evaporation inevitably takes place in the control valve, partly supercritical, since the pressure falls under the vapour pressure in each valve. This causes cavitation, erosion and vibration in the valves
Implementation Method 6
This causes cavitation, erosion and vibration in the valves, and possibly in the pipelines... the vibrations in the pipeline are very high, and therefore there is a high degree of destruction of the valve parts. This also happens since the usually conical valve head of the valve piston hits against the valve seat
Data Source
AI summary
The invention relates to a control valve, in particular an angle control valve and double control valve, for extreme control applications, preferably for discharge or reduction for hot separators and vacuum distillation columns. The valve piston and the valve head are designed as one piece and consist of tungsten carbide. Furthermore, the control valve comprises different constructions across the entire control valve range. For example, the valve housing, the valve seat and a packing retainer are optionally shaped such that the inner hollow space tapers continuously from the valve inlet to the valve seat, which prevents evaporation upstream of the valve seat. Furthermore, the double control valve consists of a large sub-valve and at least one small sub-valve, wherein the large sub-valve is designed as an adjustable open-closed piston valve and the small sub-valve is designed as a control valve.