JPH09166576A - Molten salt detecting device in boiler furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor the corrosion state of a heat transfer device by continuously detecting the adhesion state of molten salt in a boiler furnace. SOLUTION: A galvanic cell 1 in which two metallic blocks 1a, 1b made of metals different in the dipping potential to the molten salt are disposed adjacent to each other with a thin insulating material 5 interposed between them is fitted to the forward end of an insert rod 2 inserted in a boiler furnace 12 through an insulating material, and the metallic blocks 1a, 1b are connected to an ampere meter 3 through a lead wire 10. A galvanic current generated by the molten salt in adhering ash connecting the metallic blocks 1a, 1b, to each other is detected to detect the adhesion state of the molten salt in the boiler furnace 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten salt detecting apparatus for detecting a molten salt which corrodes an evaporation pipe at a high temperature during a boiler operation in a refuse incineration boiler or a coal burning boiler.

[0002]

2. Description of the Related Art In garbage incineration boilers and coal-fired boilers, when garbage and coal are burned, they are contained inside,
Salts of sodium chloride, sodium sulfate, potassium chloride, etc. generated by the chemical reaction during combustion are evaporated, and steam of these salts exists in the boiler furnace.

In a boiler furnace, for example, in a refuse incinerator, 60
Although the temperature is high from 0 to 700 ° C, of the boiler heat transfer tubes, 300 to 400 ° C for the evaporation tube and 500 to 400 for the superheated tube
Since the temperature is 550 ° C., such salt vapor is cooled on the surface of the heat transfer tube and adheres to the heat transfer tube together with the combustion ash as molten salt to cause high temperature corrosion.

Conventionally, such corrosion has been investigated by measuring the wall thickness of the pipe and analyzing the scale at the time of regular inspection of the plant.

[0005]

With the inspection method described above, it is possible to measure only when the system is not operating, such as a periodic inspection.
Since continuous monitoring was not possible, damage could occur between regular inspections.

The present invention has been devised in view of the above-mentioned problems, and an object of the present invention is to provide a molten salt detection device in a boiler furnace for continuously detecting the adhered state of molten salt in the boiler furnace during operation. And

[0007]

In order to achieve the above object, a molten salt detecting device in a boiler furnace according to the present invention has two metal blocks made of metals having different immersion potentials with respect to the molten salt and sandwiching a thin insulating material. The galvanic cells placed adjacent to each other are attached to the tip of the insertion rod to be inserted into the boiler furnace via an insulating material, and each metal block is connected to an ammeter via a lead wire to connect between the metal blocks. By detecting the galvanic current generated by the molten salt in the adhered ash thus adhered, the adhered state of the molten salt in the boiler furnace is detected.

It is preferable that both the galvanic cell and the insertion rod have a hollow cylindrical shape with substantially the same diameter, and blow cooling air through the inside.

A temperature detector such as a thermocouple may be attached to the tip of the galvanic cell or the insertion rod.

The operation of the present invention will be described below. The same principle as the battery when the molten salt adheres to the galvanic cell, which is placed adjacent to each other by sandwiching a thin insulating material between two metal blocks made of metals having different immersion potentials relative to the molten salt, and the metal blocks are connected by the molten salt. As a result, a current flows through the ammeter connected to the galvanic cell via the lead wire.

The current value is detected by an ammeter. The amount of molten salt attached and the corrosiveness can be estimated from the strength of the electric current.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a molten salt detection device of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. In FIG. 1 and FIG. 2, 1 is a galvanic cell, and two metal blocks 1a and 1b made of metals having different immersion potentials for molten salt are adjacent to each other with a thin insulating mica plate 5 of about 0.1 mm interposed therebetween. It has been arranged. 2
Is an insertion rod, the front end of which is inserted into the boiler furnace 12 through the furnace wall 9. The galvanic cell 1 and the insertion rod 2 both have a hollow cylindrical shape with substantially the same diameter, and the cooling air 8 is blown out through the inside. The galvanic cell 1 is provided with three insulating bolts 6 (made of ceramic) which penetrate the galvanic cell 1 at the tip of the insertion rod 2 for insulating mica plate 5.
Is fixed through.

Each metal block 1 of the galvanic cell 1
Each of a and 1b is connected to a non-resistance ammeter 3 via a lead wire 10, and the non-resistance ammeter 3 is connected to a recorder 4. Numeral 7 is attached ash attached to the outer periphery of the galvanic cell 1, and includes ash components such as gypsum, alumina and silica,
It is a mixture with molten salts such as sodium chloride, potassium chloride, sodium sulfate and potassium sulfate. Reference numeral 11 denotes a thermometer, which is connected to the thermocouple 11a (temperature detector) via the lead wire 10.

Next, the operation of this embodiment will be described. The insertion rod 2 having the galvanic cell 1 at its tip is inserted into the boiler furnace 12. In this case, the cooling air 8 is blown out from the tip so that the surface temperature of the galvanic cell becomes the same as the temperature of the object whose molten salt corrosion condition is to be known, for example, the evaporation tube. The temperature is measured by the thermometer 11,
The flow rate of the cooling air 8 is adjusted according to the measurement result. When the galvanic cell 1 is inserted into the boiler furnace 12 and a required time elapses, the adhered ash 7 containing the molten salt adheres to the surface of the galvanic cell 1. 2 of galvanic cell 1 due to adhered ash 7
When the metal blocks 1a and 1b are connected, a galvanic current is sent to the ammeter 3 via the lead wire 10. The ammeter 3 measures the current value, and the change over time is recorded by the recorder 4.

The amount of molten salt attached and the corrosive strength can be estimated from the strength of the electric current.

[0016]

EXAMPLE Alloy 625, which is a high nickel alloy, is used as the metal block 1a, STBA 24, which is a low alloy steel, is used as the metal block 1b, and insulating mica is sandwiched between them.
The galvanic cell was constructed. This was taken from an actual furnace boiler, put in a container, and immersed in the adhered ash heated to 550 ° C. In FIG. 3, the horizontal axis indicates elapsed time H, and the vertical axis indicates current density I (A /
³ is a graph of m ² ). The area that is the denominator of the current density is the surface area of the buried portion of STBA 24. Since the immersion potential of Alloy 625 is higher than that of STBA24, current flows from Alloy 625 to STBA24.

[0017]

As described above, in the apparatus for detecting molten salt in the boiler furnace of the present invention, the galvanic cell is inserted into the boiler furnace and the surface temperature is made substantially equal to the temperature of the boiler heat transfer tube. It is possible to monitor the state of adhesion of the molten salt to the heat pipe during operation, and thus it is possible to estimate the state of corrosion, and it is possible to prevent damage to the heat transfer pipe, which is an excellent effect.

[Brief description of the drawings]

FIG. 1 is a front view of a molten salt detection device in a boiler furnace according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a graph of experimental results of the present invention.

[Explanation of symbols]

 1 Galvanic cell 1a, 1b Metal block 2 Insert rod 5 Insulating mica plate (insulating material) 7 Adhesive ash

Claims (3)

[Claims] 1. A galvanic cell in which two metal blocks made of metals having different immersion potentials with respect to molten salt are arranged adjacent to each other with a thin insulating material sandwiched between the galvanic cells is inserted into a boiler furnace. The boiler furnace is installed by detecting the galvanic current generated by the molten salt in the adhered ash attached so as to connect between the metal blocks. Boiler furnace molten salt detection device that detects the adhered state of molten salt in the boiler. 2. The molten salt detecting device in the boiler furnace according to claim 1, wherein both the galvanic cell and the insertion rod have a hollow cylindrical shape having substantially the same diameter, and cooling air is blown out through the inside. 3. The molten salt detecting device in the boiler furnace according to claim 1, wherein a temperature detector such as a thermocouple is attached to the tip of the galvanic cell or the insertion rod.