JP2919620B2 - Heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel heat exchanger used for a hot water boiler for exchanging heat between a combustion gas and a liquid.

[0002]

2. Description of the Related Art This type of heat exchanger does not require surface treatment (glass lining, enamelling, etc.) of the entire surface of the water chamber on heat exchange members such as an inner shell, an outer shell and a tube sheet forming a water chamber. Stainless steel has come to be used. Further, in order to reduce the size and improve the heat exchange efficiency, for example, as disclosed in Japanese Utility Model Publication No. 57-15479, a large number of smoke tubes penetrating the water chamber are used.

[0003]

In the above-described conventional apparatus, the number of connecting portions between the smoke tube and the tube sheet, the tube sheet and the inner body, the tube sheet and the outer body, etc. increases, and the gaps between these connecting portions have impurities in water. Despite the use of high corrosion-resistant stainless steel, crevice corrosion is likely to occur, and there is a risk of water leakage due to perforation. In addition, the increase in the temperature of the heat transfer surface of the heat exchange member due to the improvement of the performance has also promoted the progress of crevice corrosion.

Further, in recent years, in order to prevent crevice corrosion, SUS316 (18Cr-12Ni) is used as a heat exchange member.
The use of stainless steel containing molybdenum, such as -2Mo), and the use of a connection structure in which there is no gap in the connection portion have been studied. However, this method not only complicates processing but also reduces costs. There was a problem that also increased significantly.

The present invention has been made in view of the above circumstances, and has as its object to prevent the occurrence of crevice corrosion with a simple configuration while suppressing an increase in cost.

[0006]

According to the present invention, a water chamber is formed.
Inner body, outer body, and so on
In a heat exchanger with stainless steel tubes and smoke tubes,
The tube sheet forms a combustion gas collecting chamber below the inner sheet,
A gap that gradually widens upwards at the connection between the outer shell and the flue
Forming a gap between the inner body, outer body, smoke pipe and lower pipe
It has a structure in which the potential is lower than that of the plate and the substrate is filled with an inorganic material serving as a sacrificial anode .

[0007]

With this configuration, since impurities such as iron and chlorine do not accumulate in the gaps between the connecting portions of the heat exchange member, the corrosion of the gaps is greatly suppressed, and the holes are opened even when used for a long time. In addition, the use of inexpensive stainless steel is possible, and the forming and operation of the connecting portion are not complicated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a hot water boiler according to one embodiment of the present invention, in which 1 is a heat exchanger of the hot water boiler, 2 is an annular body formed by an inner shell 3, an outer shell 4, and upper and lower tube sheets 5, 6. A combustion chamber formed inside the inner body 3; a combustion gas collecting chamber 8 provided below the water chamber 2 and the combustion chamber 7;
9 is a lower refractory member for closing the bottom of the combustion gas collecting chamber 8;
Reference numeral 10 denotes an upper refractory member that closes an upper portion of the combustion chamber 7, and 11 denotes a burner such as a gun-type oil burner that penetrates the upper refractory member 10 and faces the upper portion of the combustion chamber 7.

Reference numeral 12 denotes an exhaust gas collecting chamber provided above the water chamber 2, 13, 13,..., A smoke pipe penetrating the water chamber 2 and connecting the combustion gas collecting chamber 8 and the exhaust gas collecting chamber 12, 14 is a water supply port provided at an intermediate height position of the water chamber 2, 15 is a hot water supply pipe connected to the upper part of the water chamber 2, 16 is an exhaust gas collecting chamber 12
Exhaust pipe connected to

The heat exchange members such as the inner shell 3, the outer shell 4, the upper and lower tube sheets 5, 6 and the smoke tube 13 forming the water chamber 2 are made of SUS.
304 (18Cr-8Ni) or the like, and the connecting portions a, b, and c of the heat exchange members are TIG.
It is joined by welding such as welding or MIG welding.

As shown in FIG. 2, Si (silicon), Ca (calcium), Al (aluminum), Mg (magnesium)
One or more inorganic substances 17 are mixed and filled. The inorganic substance 17 is a mixture of particulate substances having a diameter of 0.5 to 1.5 mm. Occasionally, due to the difference in specific gravity with water, the water enters the gap and fills the gap.

According to the above-described embodiment, the gaps between the inner shell 3, the outer shell 4 and the heat exchange members such as the upper and lower tube sheets 5 and 6 forming the water chamber 2 are provided between the gaps A, B and C. Impurities such as iron and chlorine mixed in the water that induce corrosion easily accumulate and are difficult to remove, but the diameter is 0.5 to 1.5 mm in the gap between the connecting parts a, b and c of the heat exchange member. Si and C in the form of particles
a, Al, Mg and the like are filled with the inorganic substance 17 so as to fill the gap, so that impurities such as iron, chlorine and the like hardly accumulate in the gap, and the inorganic substance 17 such as Si, Ca, Al, Mg, etc. Since the potential is lower than that of stainless steel, it becomes a sacrificial anode, and the effect of suppressing corrosion is further enhanced.

Therefore, as in the prior art, the heat exchange member is made of SU.
Crevice corrosion can be prevented without using expensive stainless steel containing molybdenum such as S316 (18Cr-12Ni-2Mo) or adopting a complicated connection structure that does not cause a gap in the connection portion. In addition to the use of inexpensive stainless steel, the forming process of the connecting portion and its operation are not complicated, and the crevice corrosion can be prevented with a simple configuration without significantly increasing the cost. Things.

FIG. 3 shows another embodiment, in which an inorganic material such as Si, Ca, Al, Mg, etc.
7 is mixed with a resin 18 such as epoxy, polyester, acrylic, urethane, etc.
Are applied or filled in the gaps between the connecting portions A, B, and C of the heat exchange members such as the inner body 3, the outer body 4 and the upper and lower tube sheets 5, 6, which fill the gaps. There is an advantage that the inorganic substance 17 does not move from the gap.

The present invention relates to a heat exchanger configured as described above , wherein the lower tube sheet is curved to improve the heating of the water chamber.
To form a combustion gas collecting chamber below, and the lower tube sheet and the
Spread gradually upward at the connection between the inner and outer shells and the flue.
When a gap is formed, the gap is formed between the inner body and the outer body.
Potential is lower than the body, smoke tube and lower tube sheet, and it becomes a sacrificial anode
Filling with inorganic material not only prevents the connecting part facing the water chamber from corroding, but also allows the use of inexpensive stainless steel, and increases the cost, such as simplifying the molding process and its operations. while holding the one in which simplification of the construction, improvement in durability and corrosion resistance attained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hot water boiler showing one embodiment of a heat exchanger according to the present invention.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is an enlarged sectional view of another embodiment of the heat exchanger according to the present invention, which corresponds to a portion A in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Water chamber 3 Inner body (Heat exchange member) 4 Outer body (Heat exchange member) 6 Tube sheet (Heat exchange member) 13 Smoke tube (Heat exchange member) 17 Inorganic b Connection part B Connection part C Connection part

Claims (1)

(57) [Claims] Claims: 1. A water chamber is formed over an upper and lower tube sheet.
The inner, outer, and smoke pipes provided below are made of stainless steel.
In the heat exchanger, the lower tube sheet has a combustion gas
Forming a collective chamber at the connection between the inner shell, outer shell and smoke tube
A gap that gradually widens upward is formed, and the gap is
Lower potential compared to inner shell, outer shell, smoke tube and lower tube sheet
A heat exchanger characterized by being filled with an inorganic material serving as an anode .