JPH0842809A - Treating method for boiler feed water - Google Patents

Abstract

PURPOSE:To hold down an increase in running cost by a method wherein a water quality inspection device is provided downstream of a water softening device and, when the hardness components are detected, a chemical introducing device is operated. CONSTITUTION:A water feed pipe 1 to a boiler 4 is provided with a deaerating bypass pipe 8, a softening bypass pipe 7 and chemical introducing devices A6 and B5 by inserting a membrane deaerator 3 and a water sofetening device 2. The water softening device 2 and the membrane deaerator 3 respectively are provided downstream with a hardness leak sensor 13 and a dissolved oxygen concentration meter 16. The feed water is normally treated by the membrane deaerator 3 and the water sofetening device 2 and then fed to a boiler 4 and, when the membrane deaerator 3 is cleaned, the water is passed through the deaerating bypass pipe 8 and a deoxidizing agent is introduced into the water from the chemical introducing device B5 for the water treatment. When the water softening device is regenerated, the water is passed through the sofetening bypass pipe 7 and a scale dispersing agent is introduced into the water from the chemicak introducing device A6 for the water treatment. The aforesaid arrangement eliminates the need for a simultaneous provision of a plurality of the water treating devices, thereby contriving the saving of space and the reduction of costs.

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 hardness components and dissolved oxygen, and if the raw water is used as it is in a boiler, it causes scale accumulation and corrosion. Therefore, it is necessary to perform softening treatment or degassing treatment in advance. As a general water treatment method,
A water softening device that removes hardness components by passing water through a resin layer filled with an ion exchange resin, or water is passed through one side of a gas-liquid separation membrane and the other side is evacuated to perform deaeration. Membrane deaerators are used. The water softening device,
It is necessary to periodically regenerate it through salt water, and even in the case of a membrane degassing device, it is necessary to perform backwashing to prevent clogging, and therefore continuous treatment cannot be continued. Further, since there are cases where strict control of hardness leakage is required, as described in Japanese Patent Publication No. 5-64276, a plurality of the same processing devices are used and at least one of them is installed so that they can operate. However, in that case, the cost and the space are increased. Further, there is water treatment by chemicals as another water treatment method, and when using a chemical injection device, it can be performed with a chemical injection device smaller than the water treatment device,
Moreover, it is not necessary to stop, but there is a problem that running cost is high because a chemical is used.

[0003]

The problem to be solved by the present invention is to make it possible to always supply treated water without installing a plurality of the same water treatment devices.

[0004]

[Means for Solving the Problems] In a water supply system for a boiler, which is provided with a water treatment device for adjusting the water quality of the feed water in the middle of the water supply pipe, a bypass pipe connecting the front and rear of the water treatment device, and a bypass pipe and a water treatment device A water flow control device that controls water flow to each of them, and a chemical injection device that injects water treatment chemicals into the water supply pipe are provided.When water treatment by the device cannot be performed, water is passed to the bypass pipe to perform chemical injection. Operate the equipment and perform chemical water treatment instead of the water treatment equipment. 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,
Operate the dosing device.

[0005]

[Function] Water treatment by the equipment and water treatment by chemicals are provided side by side. When water treatment by the equipment cannot be performed, water is bypassed by the treatment equipment and chemicals are injected into the water supply to perform water treatment by chemicals. Therefore, water is not supplied without being treated, and it is not necessary to install treatment devices in parallel. If water is not sufficiently treated even though it passes through the treatment equipment, it is detected by a detector installed downstream of the treatment equipment, and chemicals are injected, so untreated water is no longer supplied. Eliminates the need to install devices in series. Since the chemicals are only used temporarily, the amount of chemicals 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 flow chart showing a water supply route to a boiler.
A membrane degassing device (3) and a water softening device (2) are inserted in the water supply pipe (1) to the boiler (4), and a degassing bypass pipe (bypassing the membrane degassing device (3) ( 8),
A softening bypass pipe (7) for bypassing the water softening device (2) is provided, and a chemical injection device A (6) for injecting a scale dispersant and a chemical injection device B (5) for injecting a deoxidant are provided in the water supply pipe. It is connected to (1). In addition, water supply pipe (1)
And branch point of degassing bypass pipe (8) and membrane degasser (3)
Between the deaerator water flow control valve (11), the degassing bypass pipe (8), the degassing bypass pipe control valve (12), the branch point of the water supply pipe (1) and the softening bypass pipe (7), and hard water. The softening device water flow control valve (9) between the softening device (2) and the softening bypass pipe control valve (1) in the middle of the softening bypass pipe (7).
0) are provided respectively. A hardness leak sensor (13) is provided downstream of the water softening device (2), a dissolved oxygen concentration meter (16) is provided downstream of the membrane degassing device (3), and a chemical injection device A (6) is provided.
The softening control device (14) connected to the device is connected to the hardness leak sensor (13), the softening device water flow control valve (9), the softening bypass piping control valve (10), and the water softening device (2) by signal lines. , A degassing control device (15) connected to the chemical injection device B (5), a degassing device water flow control valve (11), a degassing bypass piping control valve (12), a membrane degassing device (3), a dissolved gas The oxygen concentration meter (16) is connected by a signal line.

Normal water treatment is performed by a water softening device and a membrane degassing device, and the softening control device and the degassing control device open the degassing device water flow control valve and the softening device water flow control valve,
Close the degassing bypass piping control valve and the softening bypass piping control valve, perform water treatment with the water softening device and the membrane degassing device,
Do not operate the chemical injection devices A and B. The water to be passed passes through a membrane degassing device and a water softening device, is treated into water suitable for the boiler, and is supplied to the boiler.

When deaerating cannot be performed, such as when cleaning the membrane deaerator, the deaerator controller closes the deaerator water flow control valve and opens the degassing bypass piping control valve to allow water flow. Water treatment by chemicals is performed by injecting a deoxidizer from the chemical injection device B through the degassing bypass pipe. When the water softening device cannot perform softening treatment such as regeneration, the softening control device closes the softening device water flow control valve and opens the softening bypass pipe control valve to pass water through the softening bypass pipe, and then the chemical injection device. By injecting the scale dispersant from A, water treatment with chemicals is performed.

Even when water is softened by the water softening device, if the water softening device leaks hardness, a hardness leak signal is sent from the hardness leak sensor to the softening control device, and the softening control device is sent. Starts the chemical injection of the chemical injection device A to perform water treatment with chemicals. Even if the dissolved oxygen is removed by the membrane degasser, if the degassing process is insufficient and the dissolved oxygen concentration is high, the dissolved oxygen concentration meter sends a signal to the degassing controller. The deaeration control device starts the chemical injection of the chemical injection device B to perform water treatment with chemicals.

[0010]

By implementing the present invention, it is not necessary to install a plurality of the same water treatment devices even if water supply is always required and water quality control is strictly required, which saves space and cost. It can be reduced.

[Brief description of drawings]

FIG. 1 is a flow chart of an embodiment of the present invention.

[Explanation of symbols]

 1 Water Supply Pipe 2 Membrane Deaerator 3 Hard Water Softener 4 Boiler 5 Chemical Dosing Device B 6 Chemical Dosing Device A 7 Softening Bypass Piping 8 Degassing Bypass Piping 9 Softening Device Water Flow Control Valve 10 Softening Bypass Piping Control Valve 11 Degassing Device Water flow control valve 12 Degassing bypass piping control valve 13 Hardness leak sensor 14 Softening control device 15 Degassing control device 16 Dissolved oxygen concentration meter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display C02F 5/08

Claims (4)

[Claims] 1. In a water supply system of a boiler in which water quality is adjusted in the middle of a water supply pipe to supply water to the boiler, a hardness leak for detecting the presence or absence of a hardness component downstream of a water softening device provided in the water supply system. A sensor, and a chemical injection device for injecting a chemical that prevents scale adhesion is provided further downstream, and when a hardness component is detected by a hardness leak sensor, the chemical injection device is activated to supply water to the boiler supply water. Processing method. 2. Dissolved oxygen for detecting a dissolved oxygen concentration downstream of a membrane degassing device provided in a water supply system in a water supply system of a boiler in which water quality is adjusted in the middle of a water supply pipe to supply water to the boiler. A concentration meter and a chemical injection device for injecting a chemical that removes dissolved oxygen are provided further downstream, and the chemical injection device is activated when the dissolved oxygen concentration is detected to be high. A water treatment method for boiler feed water, characterized by: 3. In a water supply system of a boiler in which water quality is adjusted in the middle of the water supply pipe for supplying 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 softening 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 feed water, characterized in that the feed water is not sent to the water softening device but is sent to the bypass pipe, the hardness component is not removed by the water softening device, and the chemical injection device is operated to perform water treatment with chemicals. . 4. In a water supply system of a boiler in which the water quality is adjusted in the middle of the water supply pipe for supplying 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 degassing devices, and a chemical injection device that injects a chemical that removes dissolved oxygen into water that has not passed through the membrane degassing device is provided in advance. When cleaning, the feed water is not sent to the membrane degassing device but to the bypass pipe, the dissolved oxygen is not removed by the membrane degassing device, and the chemical injection device is operated to perform water treatment with chemicals. Water treatment method for boiler feed water.