Drain Recovery System Pressure Equalization
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Solution Overview
Problem
Conventional closed scheme drain recovery systems cannot fully reduce power consumption for driving the feedwater pump due to pressure differences between the drain recovery tank and the boiler, limiting the efficient supply of feedwater.
Innovation Solution
A closed scheme drain recovery system with a buffer tank, an assist tank, and a communication line between them, along with a control unit to manage valve operations, equalizes pressures and optimizes the supply of drain to the boiler, reducing the need for pump power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pressure inside the drain recovery tank is fully raised to reduce feedwater pump power consumption, then the pressure difference between the drain recovery tank and the boiler is reduced, but the feedwater cannot be supplied to the boiler because the pressure inside the drain recovery tank becomes higher than the pressure inside the boiler
Solution Approach 1:
The drain recovery system is divided into two separate tanks: a buffer tank for receiving drain from the load device and an assist tank for storing drain before supply to the boiler. This segmentation allows each tank to operate at different pressure levels independently, resolving the contradiction between raising pressure to reduce pump power and maintaining the ability to supply feedwater to the boiler.
Solution Approach 2:
The buffer tank acts as an intermediary between the load device and the assist tank, and the communication line with communication valve serves as an intermediary mechanism to equalize pressures. This intermediary structure enables the system to maintain appropriate pressure differences for both drain reception and feedwater supply, eliminating the need for the feedwater pump while ensuring reliable feedwater supply to the boiler.
2Loss of energy
If the pressure inside the drain recovery tank is raised to reduce feedwater pump power consumption, then fuel consumption of the boiler is reduced, but the pressure inside the drain recovery tank becomes higher than the pressure inside the boiler, preventing feedwater supply
Solution Approach 1:
By segmenting the drain recovery system into a buffer tank and an assist tank, the system can maintain high pressure in the assist tank to reduce fuel consumption while the buffer tank manages the pressure differential for feedwater supply. This segmentation allows independent optimization of each function without compromising the other.
Solution Approach 2:
The communication line with communication valve serves as an intermediary pressure equalization mechanism between the buffer tank and assist tank. This intermediary allows the system to equalize pressures when needed, enabling the assist tank to operate at high pressure for fuel savings while maintaining the ability to supply feedwater to the boiler through the feedwater line.
3Loss of energy
If a closed scheme drain recovery system is used to supply feedwater at higher temperatures, then fuel consumption and driving costs are reduced, but the pressure difference between the drain recovery tank and the boiler cannot be fully eliminated, so feedwater pump power cannot be fully reduced
Solution Approach 1:
The system segments the drain recovery function into two tanks with different roles: the buffer tank receives drain at lower pressure while the assist tank stores drain at high pressure. This segmentation enables the system to achieve high feedwater temperature supply (reducing driving costs) while completely eliminating the need for feedwater pump power through proper pressure management in the assist tank.
Solution Approach 2:
The communication line with communication valve acts as an intermediary that enables pressure equalization between the buffer tank and assist tank. This intermediary mechanism allows the system to maintain the necessary pressure differential for high-temperature feedwater supply while being able to equalize pressures to completely reduce feedwater pump power consumption when needed.
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 reduces power consumption for driving the feedwater pump by equalizing pressures and optimizing the supply of feedwater to the boiler, allowing for low-cost operation.
Implementation Method 1
a communication line that connects the assist tank and the buffer tank to each other to establish communication between an inner space of the assist tank and an inner space of the buffer tank
Implementation Method 2
a steam supply line that connects the boiler and the assist tank to each other to supply the steam generated at the boiler to the assist tank
Implementation Method 3
recovers drain being generated by condensation of steam having been generated at a boiler and used at a load device
Implementation Method 4
a feedwater pump that is disposed at the feedwater line
Data Source
AI summary
There is provided a drain recovery system with which power for driving a feedwater pump can be reduced and the feedwater pump can be driven at low costs. The drain recovery system includes: a buffer tank; an assist tank disposed below the buffer tank; a first drain supply line that connects a load device and the buffer tank; a second drain supply line that connects the buffer tank and the assist tank; a drain supply valve; a communication line that establishes communication between the assist tank and the buffer tank; a communication valve; a steam supply line that supplies steam from a boiler to the assist tank; a steam supply valve; a feedwater line that supplies drain from the assist tank to the boiler; and a feedwater pump.