Centrifugal Compressor Impeller Tuning for Wider Operating Range
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Solution Overview
Problem
Centrifugal compressors with high gas Mach numbers experience a narrowed operation range, particularly in applications like ethylene and LNG plants where the gas has high molecular weight, limiting performance and efficiency.
Innovation Solution
The centrifugal compressor design includes a rotary shaft with impellers configured to operate between specific flow rate coefficient values, with a design point of 0.1 to 0.2 and a machine Mach number of 1.1 to 1.3, ensuring an operation range of 30% or higher, achieved by adjusting the outlet width of the diffuser part and the curvature and angle of the flow path walls to manage gas flow velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the Mach number of the gas in the impeller is increased to improve compression performance, then the compression ratio and efficiency are improved, but the operation range is narrowed
Solution Approach 1:
The patent applies parameter changes by optimizing the flow rate coefficient to a specific range (0.1 to 0.2) and controlling the Mach number (1.1 to 1.3) to achieve both high compression performance and adequate operation range. This resolves the contradiction by finding the optimal parameter window that satisfies both requirements simultaneously.
2Adaptability or versatility
If the flow rate coefficient is increased to widen the operation range, then the adaptability is improved, but the compression performance decreases
Solution Approach 1:
The patent specifies a flow rate coefficient range of 0.1 to 0.2 that simultaneously achieves both adequate operation range and high compression performance. This parameter optimization resolves the contradiction by identifying the sweet spot where both adaptability and productivity are maximized.
3Productivity
If the centrifugal compressor is designed for high molecular weight gases (ethylene plant, LNG plant), then the specific compression capability is improved, but the Mach number becomes particularly high which narrows the operation range
Solution Approach 1:
The patent addresses high molecular weight gas compression by controlling the Mach number to 1.1 to 1.3 and flow rate coefficient to 0.1 to 0.2, which maintains both high compression capability for heavy gases and adequate operation range despite the inherently high Mach numbers associated with high molecular weight gases.
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 enhances performance and widens the operation range, preventing surging and allowing efficient operation even with high flow rates and molecular weights, specifically in ethylene and LNG applications.
Implementation Method 1
a plurality of impellers fixed to and which is configured to integrally rotate with the rotary shaft so that a gas flowing from an upstream side in an axial direction is compressed by being pumped outward in a radial direction
Data Source
AI summary
A centrifugal compressor includes a rotary shaft rotating around an axis, and a plurality of impellers fixed to and integrally rotating with the rotary shaft so that a gas flowing from an upstream side in an axial direction is compressed by being pumped outward in a radial direction. At least one of the plurality of impellers has a design point of a flow rate coefficient φ which is 0.1 to 0.2, and a machine Mach number M0 of 1.1 to 1.3 and is configured to be operable between a flow rate coefficient minimum value φmin and a flow rate coefficient maximum value φmax. An operation range expressed by the following Equation (a) is 30% or higher,(Operation Range)={(Flow Rate Coefficient Maximum Value φmax)−(Flow Rate Coefficient Minimum Value φmin)}/(Flow Rate Coefficient Maximum Value φmax) (a).