JP2853098B2 - Water treatment method for boiler feed water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating boiler feed water.

[0002]

2. Description of the Related Art Raw water contains a hardness component and dissolved oxygen, and if raw water is used as it is in a boiler, scale deposition and corrosion will occur. Therefore, it is necessary to perform a softening treatment and a degassing treatment in advance. As a general water treatment method,
Dewatering is performed by passing water through one side of a gas-liquid separation membrane and applying vacuum to the other side, or a water softening device that removes hardness components by passing water through a resin layer filled with ion exchange resin. A membrane deaerator is used. The above water softener,
It is necessary to periodically regenerate through salt water, and also in the case of a membrane deaerator, it is necessary to perform backwashing to prevent clogging, so that the treatment cannot be continued continuously. In addition, since strict control may be required for hardness leakage, as described in Japanese Patent Publication No. 5-64276, a plurality of the same processing apparatuses are used, and at least one of the processing apparatuses is installed so that it can be operated. However, in that case, cost and space are increased. Another water treatment method is water treatment by chemicals, and when using a chemical injection device, it can be performed with a small chemical injection device as compared to the water treatment device,
In addition, there is no need to stop the operation, but there is a problem that the running cost is high because the chemical is used.

[0003]

An object of the present invention is to make it possible to always supply treated water without installing a plurality of the same water treatment apparatuses.

[0004]

Means for Solving the Problems A water supply system for a boiler provided with a water treatment device for adjusting the quality of water supply in the middle of the water supply piping is provided with a bypass piping connecting the front and rear of the water treatment device, a bypass piping and a water treatment device. A water flow control device that controls the flow of water to each, and a chemical injection device that injects water treatment chemicals into the water supply piping are provided. When water treatment by the device cannot be performed, water is supplied to the bypass piping, and chemical injection is performed. The apparatus is operated, and water treatment using chemicals is performed instead of the water treatment apparatus. In addition, an inspection device for inspecting water quality is provided downstream of the water treatment device, and when it is detected that the water treatment by the device is not sufficiently performed,
Activate the dosing device.

[0005]

[Function] Water treatment by a device and water treatment by a chemical are installed in parallel, and when water treatment by the device cannot be performed, water treatment is performed by bypassing the water flow and injecting the chemical into the supply water. Therefore, water is not supplied without being treated, and it is not necessary to install treatment devices in parallel. In addition, when the water treatment is not sufficiently performed even though the water passes through the treatment device, the detection is performed by the detection device provided downstream of the treatment device, and the chemical is injected. There is no need to install devices in series. Since the chemical is only used temporarily, the amount of chemical used can be kept low, and the increase in running cost can be suppressed.

[0006]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing a water supply path to a boiler.
In the middle of the water supply pipe (1) to the boiler (4), a membrane deaerator (3) and a water softener (2) are inserted, and a deaeration bypass pipe () that bypasses the membrane deaerator (3). 8),
A softening bypass pipe (7) for bypassing the water softener (2) is provided, and a chemical injection device A (6) for injecting the scale dispersant and a chemical injection device B (5) for injecting the oxygen scavenger are provided by water supply piping. It is connected to (1). In addition, water supply piping (1)
And deaeration bypass pipe (8) junction and membrane deaerator (3)
Between the deaeration device water flow control valve (11), the deaeration bypass piping (8), the deaeration bypass piping control valve (12), the water supply piping (1) and the branch point of the softening bypass piping (7) and hard water. A softening device flow control valve (9) is provided between the softening devices (2), and a softening bypass piping control valve (1) is provided in the middle of the softening bypass piping (7).
0) are provided. A hardness leak sensor (13) is provided downstream of the water softener (2), and a dissolved oxygen concentration meter (16) is provided downstream of the membrane deaerator (3).
Connected to the softening control device (14) connected to the hardening leak sensor (13), the softening device water flow control valve (9), the softening bypass pipe control valve (10), and the water softening device (2) by signal lines. , A deaeration device water flow control valve (11), a deaeration bypass pipe control valve (12), a membrane deaeration device (3), and a dissolution to a deaeration control device (15) connected to a chemical injection device B (5). The oximeter (16) is connected by a signal line.

[0007] Normal water treatment is performed by a water softening device and a membrane deaerator, and the softening control device and the deaeration controller open the deaerator water control valve and the softener water control valve,
Close the deaeration bypass pipe control valve and the softening bypass pipe control valve, perform water treatment with a water softener and a membrane deaerator,
The chemical injection devices A and B are not operated. The water passed is passed through a membrane deaerator and a water softener, processed into water suitable for the boiler, and supplied to the boiler.

When deaeration cannot be performed, such as when cleaning the membrane deaerator, the deaeration controller closes the deaerator flow control valve and opens the deaeration bypass pipe control valve to release water. The treatment is performed through a degassing bypass pipe, and a deoxidizer is injected from the chemical injection device B to perform water treatment with a chemical. When the water softening device cannot perform the softening treatment due to regeneration or the like, the softening control device closes the softening device water flow control valve, opens the softening bypass pipe control valve, performs water flow through the softening bypass pipe, and performs the chemical injection device. Water treatment with a chemical is performed by injecting a scale dispersant from A.

[0009] Even if the water is softened by the water softening device, if the water softening device leaks the hardness, a hardness leak signal is sent from the hardness leak sensor to the softening control device, and the softening control device Performs water treatment with chemicals by starting chemical injection of the chemical injection device A. Even when the dissolved oxygen is removed by the membrane deaerator, if the deaeration is insufficient and the dissolved oxygen concentration is high, a signal is sent from the dissolved oxygen concentration meter to the deaeration controller. The degassing control device performs water treatment with a chemical by starting the chemical injection of the chemical injection device B.

[0010]

According to the present invention, even when water supply is always required and water quality control must be strictly performed, it is not necessary to install a plurality of the same water treatment devices, and space and cost can be reduced. Reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a flowchart of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water supply pipe 2 Membrane deaerator 3 Water softening device 4 Boiler 5 Chemical injection device B 6 Chemical injection device A 7 Softening bypass piping 8 Deaeration bypass piping 9 Softening device flow control valve 10 Softening bypass piping control valve 11 Deaerator Flow control valve 12 Deaeration bypass pipe control valve 13 Hardness leak sensor 14 Softening control device 15 Deaeration control device 16 Dissolved oxygen concentration meter

Claims (4)

(57) [Claims] In a water supply system of a boiler for adjusting water quality in the middle of a water supply pipe in order to supply water to a boiler, a hardness leak for detecting the presence or absence of a hardness leak downstream of a water softening device provided in the water supply system. A boiler feed water is provided, in which a sensor and a chemical injection device for injecting a chemical for preventing scale adhesion are further provided downstream, and when a hardness leak is detected by a hardness leak sensor, the chemical injection device is operated. Processing method. 2. A system for detecting dissolved oxygen concentration downstream of a membrane deaerator provided in a water supply system in a water supply system of a boiler for adjusting water quality in a water supply pipe to supply water to the boiler. A concentration meter and a chemical injection device for injecting a chemical for removing dissolved oxygen are provided further downstream, and when the dissolved oxygen concentration is detected as high by the dissolved oxygen concentration meter, the chemical injection device is operated. A method for treating boiler feed water. 3. In a water supply system of a boiler for adjusting water quality in the middle of a water supply pipe in order to supply water to the boiler, a bypass pipe connecting the front and rear of a water softening device provided in the water supply system, a bypass pipe, and water hardening. A water flow control device that controls water flow to each of the devices, a chemical injection device that injects a chemical that prevents scale adhesion to water that has not passed through the water softening device is provided, and when regenerating the water softening device, A water treatment method for boiler-supplied water, wherein the water supply is sent to a bypass pipe without being sent to the water softening device, and the water component is not removed by the water softening device, but the chemical injection device is operated to perform water treatment with a chemical. . 4. In a water supply system of a boiler for adjusting water quality in the middle of a water supply pipe to supply water to the boiler, a bypass pipe connecting the front and rear of a membrane deaerator provided in the water supply system, a bypass pipe, and a membrane. A water flow control device that controls water flow to each of the deaerators and a chemical injection device that injects a chemical that removes dissolved oxygen into water that has not passed through the membrane deaerator are provided. In the case of washing, feed water is sent to a bypass pipe without being sent to a membrane deaerator, and dissolved oxygen is not removed by the membrane deaerator, but a chemical injection device is operated to perform water treatment with a chemical. Water treatment method for boiler feed water.