Cryogenic Pump Feed Layout to Suppress Cavitation in Power Recovery
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Solution Overview
Problem
Existing power recovery systems for liquefied gases face issues with cavitation and gas suction in pumps due to the low boiling point of the working fluid, leading to pump damage and operational inefficiencies, which are exacerbated by large reservoir tanks and temperature differences.
Innovation Solution
A power recovery system with a condenser, gas-liquid separation tank, cryogenic pump, evaporator, and cryogenic turbine, where the outlet port of the first conduit is located below the liquid level of the gas-liquid separation tank, ensuring the working fluid is supplied in a low-temperature state to the pump, thereby suppressing gasification and cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large capacity liquid reservoir tank is used to suppress gasification in the pump portion, then gasification is suppressed, but the heat transfer area with the surrounding atmosphere increases, heating the working fluid and making bubble generation easier
Solution Approach 1:
An insulation layer is introduced as an intermediary between the working fluid and the surrounding atmosphere. This insulation layer acts as a thermal barrier that reduces heat transfer from the atmosphere to the working fluid in the liquid reservoir tank, thereby suppressing unwanted heating and bubble generation while allowing the tank to maintain its gasification-suppressing capacity.
Solution Approach 2:
The thermal insulation parameters of the liquid reservoir tank are modified by adding an insulation layer with specific thermal conductivity and thickness characteristics. This changes the heat transfer rate parameter, reducing the temperature rise of the working fluid while maintaining the tank's ability to suppress gasification through its large capacity.
2Reliability
If a large water level head is disposed between the liquid reservoir tank and the pump to suppress gasification, then gasification is suppressed, but the temperature difference between the heated pump and the working fluid increases, facilitating gasification
Solution Approach 1:
The working fluid is pre-cooled in the liquid reservoir tank before being supplied to the pump. By maintaining the fluid at a lower temperature in advance through the insulation barrier, the temperature difference between the pump and working fluid is reduced, preventing gasification at the pump inlet while still utilizing the necessary water level head for reliable pump operation.
3Reliability
If the working fluid temperature is lowered to saturated vapor pressure in the condenser, then condensation is achieved, but the working fluid may locally evaporate in the pump portion causing cavitation
Solution Approach 1:
The liquid reservoir tank with insulation provides a cushioning effect by maintaining the working fluid at a controlled temperature before pump intake. This pre-conditioning prevents the working fluid from reaching its vapor pressure and causing cavitation in the pump, while still allowing efficient condensation to occur in the condenser where the fluid is deliberately cooled to saturated vapor pressure.
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 system effectively prevents cavitation and gas suction in the cryogenic pump, enabling normal operation and improving the efficiency of the power recovery process.
Implementation Method 1
a condenser (2) configured to condense the working fluid by heat exchange between the working fluid and the liquefied gas
Implementation Method 2
a gas-liquid separation tank (4) configured to separate the working fluid condensed in the condenser (2) into liquid and gas
Implementation Method 3
an evaporator (8) configured to evaporate the working fluid boosted by the cryogenic pump (6), by heat exchange between the working fluid and a heating fluid introduced from outside the power recovery system
Data Source
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AI summary
Provided is a power recovery system for recovering, as power, cold energy of a liquefied gas via a working fluid for heating the liquefied gas, including: a condenser; a gas-liquid separation tank; a cryogenic pump; an evaporator; a cryogenic turbine; and a first conduit configured to supply the working fluid condensed by the condenser to the gas-liquid separation tank, the first conduit being configured such that an outlet port of the first conduit is located below a liquid level of the gas-liquid separation tank.