Liquid level control system
AssigneeHitachi, Ltd.
InventorTatsuro Kozaki
Life of this patent
Estimating the term…
Abstract
A water level control system for enhancing the controllability of the level of water retained in a steam drum. A water level control section of the system determines the volume of retained water in a steam-water separator from a detected steam flow rate signal by using a function operator and a first order lag circuit, determines a signal representing the mass flow rate balance of water in the steam-water separator by differentiating the volume of retained water with respect to time with a differentiator, generates a compensated signal by adding the signal to the difference between a detected feed water flow rate signal and the detected steam flow rate signal, and properly compensates a valve area demand for a feed water flow control valve.
Claims13
A liquid level control system comprising:
- a boiler which boils liquid;
- a steam-liquid separator which separates the liquid from two-phase fluid containing steam and liquid flowing out of the boiler and allows the separated liquid to fall;
- a steam drum which contains the steam-liquid separator, supplies the liquid-free steam to a turbine, and supplies the internally retained liquid to the boiler;
- feed liquid flow rate adjustment means which is capable of adjusting the flow rate of feed liquid supplied from a steam condenser to the steam drum;
- a level meter for detecting a liquid level of the liquid retained in the steam drum;
- a flowmeter for detecting a feed liquid flow rate of the feed liquid supplied from the steam condenser to the steam drum;
- a flowmeter for detecting a steam flow rate of the steam supplied from the steam drum to the turbine;
- and
- liquid level control means which uses the feed liquid flow rate adjustment means to control the feed liquid flow rate in accordance with the detected liquid level, feed liquid flow rate, and steam flow rate;
- wherein the liquid level control means determines a change rate of the volume of liquid retained in the steam-liquid separator, and allows the feed liquid flow rate adjustment means to compensate the feed liquid flow rate in accordance with the determined change rate of the volume of liquid.
A liquid level control system comprising:
- a boiler which boils liquid;
- a steam-liquid separator which separates the liquid from two-phase fluid containing steam and liquid flowing out of the boiler and allows the separated liquid to fall;
- a steam drum which contains the steam-liquid separator, supplies the liquid-free steam to a turbine, and supplies the internally retained liquid to the boiler;
- feed liquid flow rate adjustment means which is capable of adjusting the flow rate of feed liquid supplied from a steam condenser to the steam drum;
- a level meter for detecting a liquid level of the liquid retained in the steam drum;
- a flowmeter for detecting a feed liquid flow rate of the feed liquid supplied from the steam condenser to the steam drum;
- a flowmeter for detecting a steam flow rate of the steam supplied from the steam drum to the turbine;
- and
- liquid level control means which uses the feed liquid flow rate adjustment means to control the feed liquid flow rate in accordance with the detected liquid level, feed liquid flow rate, and steam flow rate;
- wherein the liquid level control means determines a change ratio of the total volume of voids in liquid retained in the boiler and the steam drum, and allows the feed liquid flow rate adjustment means to compensate the feed liquid flow rate in accordance with the determined change ratio of the total volume of voids.
Dependencies are inferred from the claim text.