JPS602891A - Corrosion prevention type heat exchanging device - Google Patents

Abstract

PURPOSE:To limit the range of corrosion and dust adhesion caused by a mist, also simplify the removing of dust with a bare pipe structure by providing a high temperature pipe group for evaporating of the mist. CONSTITUTION:An exhaust gas from a burning device 20 is introduced as a high temperature exhaust gas G1 into a duct 1 in which plural evaporating pipe groups are located, flowed through a purifying device 22 after heat exchanging, flowed as a low temperature gas G2 through a duct 2 in which condensing pipe groups are located, discharged from a smokestack 23 after temperature rising. In this case, when the temperature of a condensing pipe 9a and gas G2 are low, a undesirable white smoke containing steam is discharged, thereby, a high temperature medium vapor generated with an evaporating pipe group 18 provided at the most upstream side of an evaporating groups 5a, 5b and 5c of the exhaust gas G1 flow is introduced to a condensing group 19 located at the most upstream side of a low temperature gas G2 flow, accordingly, the heat transferring pipe of the condensing pipe group 19 can be prevented from the condensing of the mist. The prevention of the mist adhesion and the corrosion can be successively achieved by utilizing the bare pipe made of a corrosion resistant material for the heat transferring pipe.

Description

Detailed Description of the Invention This invention uses a separate heat pipe device to raise the temperature of low-temperature gas, such as exhaust gas from a combustion device, after desulfurization, thereby preventing white smoke and preventing corrosion of heat transfer tubes. The present invention relates to the structure of a heat exchange device.

Figure 1 shows the structure of the separate heat pipe.
Reference numeral 5 denotes a group of evaporation tubes arranged in the duct 1 through which heating fluid (gas, etc.) flows, and the transferred heat is transferred to the upper part of the duct 1 through the ladder 6 through the pipe line 7. It is conveyed to the upper header 8 of the condensing tube bank 9 located in the flowing duct 2. This vapor condenses and flows into the ladder 4 from the lower spatula O through the pipe line 11 to the lower part of the evaporator tube group.

Since the lower header 10 is located at a higher level than the lower ladder 4, evaporation and condensation occur through natural circulation of the medium.

The pipe line 7 is provided with a safety valve] 7 and a valve 16 for removing non-condensable gas.

FIG. 2 is a drawing schematically showing this structure.

In this case, if the exhaust gas G2 to be heated is the exhaust gas that has passed through the desulfurization device, the evaporator tube group 5a is located at the most downstream position in the duct 1 with respect to the flow of the high-temperature exhaust gas G1, so the temperature of the medium in the tubes is the lowest. Correspondingly, the temperature of the condensing tube group 9a is also low, and if the exhaust gas containing the sulfuric acid mist flows therein, it will condense on the surface of the tubes and corrode the tubes. In addition, if the tubes in the condensing tube group 9a are finned tubes, there is a problem in that dust gets clogged between the fins, poor heat transfer occurs, and the tubes are rapidly corroded by condensation of the mist.

The purpose of this invention is to eliminate such drawbacks and to propose a structure of a heat exchange device with high corrosion resistance.

In short, the present invention provides a separate type heat pipe device in which an evaporator tube group is provided upstream of another evaporator tube group for high-temperature gas flow, and a condensing tube group connected to this evaporator tube group is formed from bare tubes made of a corrosion-resistant material. and is characterized by being a corrosion-proof heat exchange device installed upstream of other condensing tube groups for low-temperature gas flow.

An embodiment of this invention will be explained with reference to FIG.

Exhaust gas from a combustion device 2o such as a boiler passes through a device such as a dust collector 21, flows into the duct 1 where a plurality of evaporator tube groups are located as high-temperature exhaust gas G, and after exchanging heat, is transferred to a desulfurization device 22.
The gas flows into the cooling tower 22a, where it is cooled by water spray, and the absorption tower 22b, where it is washed with a spray of liquid containing Oa 00s, etc., and then flows up through the duct z where the condensing pipe group is located as a low-humidity gas G2 via the demistani membrane 22c. It is heated and discharged from the chimney 23.

In this case, if the temperature of the condensing pipe 9a and the temperature of the 02 gas are low, white smoke containing water vapor will be discharged from the chimney 23, resulting in an unfavorable situation related to pollution.

In Fig. 3, the evaporator tube group 5a is located at the lowest temperature for G1 gas, and the condensing tube group 9a is located at the lowest temperature for G2 gas. (!asO+.

This causes clogging with dust particles such as Q a O03, and corrosion of the pipes forming the condensing pipe group 9a progresses rapidly. 9b,
The same applies to the tube group 9c.

For this reason, if the heat transfer tubes (9a, 9b, 9c) are all bare tubes with smooth surfaces, the number of tubes will be 4 to 5 times larger in terms of heat transfer area.

Fig. 3 shows a so-called counter-flow/co-current combination type, in which the evaporator tube group 18 is positioned at the most upstream position, different from these combinations, regarding the exhaust gas G and flow of the evaporator tube groups 5a, 5b, and 5c. A medium vapor (e.g. 124'c 2.3 Kg/cmJ) is generated and the medium vapor is sent to the condenser tube group 9 located most upstream with respect to the cold gas stream G2.Therefore, the heat exchanger tubes of this condenser tube group 19 are Mist does not condense.In this case, if the heat transfer tube is made of a corrosion-resistant material (for example, SUS stainless steel) and has a smooth surface, so-called bare tube, it will be extremely effective in preventing mist adhesion and corrosion. It is something that plays.

There may be multiple loops for mist evaporation as shown in Figure 4, and if the high temperature side inlet humidity is high and the temperature of the mist evaporation loop becomes too high, stress corrosion due to C1 etc. in the mist is considered. 9c is the high temperature fluid side tube group of the mist evaporation loop.

An appropriate temperature can be set by selecting the arrangement position of the 9b loop.

Furthermore, this means can be applied not only to latent heat transport but also to sensible heat transport.

By implementing this invention, by providing a group of high-temperature tubes for evaporation, corrosion caused by mist and dust adhesion can be limited to a narrow range, and by using bare tubes, it is easy to remove adhering dust. The device can be operated continuously, and the time required for maintenance and inspection can be reduced.

[Brief explanation of drawings]

Fig. 1 is a drawing showing the structure of a separate type heat vibrator, Fig. 2 is a drawing schematically showing Fig. 1, and Fig. 3 is an exhaust gas from a desulfurization device attached to a combustion device showing an embodiment of the present invention. A drawing showing the structure of a device used as a means to prevent accidents caused by mist inside the tank and white smoke. FIG. It is a diagram. 1.2... Duct G1... High temperature gas G2... Low temperature gas 18... Evaporation tube group 19... Condensing tube group 20... Combustion Device 22...Desulfurization device

Claims (1)

[Claims] 1. In a separate heat pipe device, an evaporator tube group is provided upstream of one or more other evaporator tube groups for high-temperature gas flow, and a condensation tube group connected to this evaporator tube group is provided for low-temperature gas flow. A corrosion-preventing heat exchange device characterized in that it is installed upstream of one or more other condensing tube groups in terms of flow. 2. Claim 1, characterized in that the condensing tube provided upstream of the other condensing tube group for low-temperature gas flow is formed only of bare tubes, and the other condensing tubes and evaporation tubes are finned tubes. Corrosion-proof heat exchange device as described. 3. The corrosion-preventing heat exchange device according to claim 2, wherein the bare tube is made of a corrosion-resistant material.