CN102345997B - Dew point corrosion resistant method for flue gas heat exchanger - Google Patents
Dew point corrosion resistant method for flue gas heat exchanger Download PDFInfo
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- CN102345997B CN102345997B CN2011102953215A CN201110295321A CN102345997B CN 102345997 B CN102345997 B CN 102345997B CN 2011102953215 A CN2011102953215 A CN 2011102953215A CN 201110295321 A CN201110295321 A CN 201110295321A CN 102345997 B CN102345997 B CN 102345997B
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Abstract
The invention discloses a dew point corrosion resistant method for a flue gas heat exchanger. The method preferably comprises the following steps: 1) a flow rate regulating valve and a temperature measuring and controlling device which can receive control signals are arranged on a steam pipeline; and 2) the flow rate regulating valve receives the control signals of the temperature measuring and controlling device, and regulates the aperture automatically, so that the steam temperature is kept above the preset temperature which is higher than the dew point temperature of flue gas. Through the dew point corrosion resistant method for the flue gas heat exchanger, the temperature of a heat exchange pipe wall which exchanges heat with flue gas is always higher than the dew point temperature, and the dew point corrosion is avoided; and the dew point corrosion is avoided, and a higher steam flow rate and a residual heat recycling effect are obtained.
Description
Technical field
The present invention relates to the anticorrosion field of heat exchanger, be specifically related to a kind of preventing corrosion of dew points method that is used for the flue gas heat exchange device.
Background technology
In enterprises such as chemical industry, metallurgy, industrial furnaces such as heating furnace, boiler often will consume a large amount of fuel, are important energy consumption equipment.Therefore the waste heat in the flue gas that reclaims fuel combustion and produced becomes the energy-saving and cost-reducing emphasis of these enterprises; Wherein the application of air preheater is a kind of heat recovery technology commonly used; Air preheater generally is called for short air preheater; It reclaims the waste heat in the flue gas and is used for the air before preheating gets into this industrial furnace through heat exchange, thereby improves the thermal efficiency of this industrial furnace, reduces its burnup.
Air preheater commonly used at present has tubular air preheater and rotary regenerative air preheater.The main heat transfer component of tubular air preheater is a thin-wall steel tube.Steel pipe vertical interlaced is each other arranged, and two ends are welded on the lower perforated plate.Tubular air preheater is equipped with sagging plate in bobbin carriage, up and down through preheater, air is accomplished the heat conduction then laterally through preheater to flue gas along steel pipe.Rotary regenerative air preheater is to utilize flue gas and air alternately to add hot-air through metal heated.
Publication number is that 1412475 one Chinese patent application has disclosed a kind of separated heat pipe heat exchanger that is mainly used in air preheater in the prior art; See Fig. 1; Its heat exchanger tube has been divided into evaporator section 1 and condensation segment 2; The position of condensation segment 2 is higher than evaporator section 1, and is linked to each other with condensed water down-comer 4 by vapor uptake 3 respectively between the two.Water explosive evaporation with high-temperature flue gas generation heat exchange in the heat exchanger tube of evaporator section 1 as heat transferring medium and intermediate heat carrier; The water vapour that forms gets in the heat exchanger tube of condensation segment 2 through vapor uptake 3; Be condensed into water after the air generation heat exchange of treating preheating; Water flows back to again in the heat exchanger tube of evaporator section 1 through condensed water down-comer 4 under the gravity effect, has formed closed circulation.The advantage of this split type air preheater has been to utilize the latent heat of vaporization of water and steam phase transformation to transmit heat, and heat transfer efficiency is high, and available less steam flow transmits a large amount of heats, thus air preheater can design and produce very compact; Needs are carried out the split-type structural flexible arrangement that the cold and hot medium of heat exchange thoroughly separates, and range of application is more extensive.Yet several kinds of above-mentioned air preheaters all can't solve the problem of the dew point corrosion under the flue gas low-temperature fully.The dew point corrosion of flue gas is meant owing to element sulphur in the fuel generates SO when burning
2, SO
3, when the hull-skin temperature of heat-transfer surface is lower than flue-gas temperature, on heat-transfer surface, will form the sulfuric acid mist dewdrop, cause the heat-transfer surface corrosion.The approach that solves dew point corrosion at present mainly contains two kinds, a kind of material for the employing dew-point corrosion resistant, however its effect is limited; Another kind of for avoiding dew point corrosion, promptly the temperature of the heat exchange tube wall of control and flue gas heat exchange make it to be higher than the dew point problem all the time, but in actual moving process, the problem of heat exchange tube wall is difficult to accomplish adjustable controlled.
Summary of the invention
Because the above-mentioned defective of prior art the invention provides a kind of preventing corrosion of dew points method that is used for the flue gas heat exchange device.
Because the generation of low-temperature dew point corrosion is just not relevant with the height of exhaust gas temperature, and main be the tube wall temperature that depends on the heat exchange tube wall that contacts with flue gas.Therefore as long as the heat exchanger tube wall temperature of control and flue gas heat exchange makes it be higher than dew-point temperature, just can avoid the generation of dew point corrosion.
The two phase flow air preheater has utilized the latent heat of vaporization of water and steam phase transformation to transmit heat, and when contacting with flue gas, the water in the heat exchanger tube in the evaporator section is heated to boiling point, gets into condensation segment after flashing to water vapour.And waste heat boiler produces steam through the water in the heating of the waste heat in the flue gas heat pipe equally; Therefore if can the boiling temperature of water be remained on the dew-point temperature of flue gas; Because the heat of flue gas passes to water through the heat exchange tube wall, is the unidirectional diabatic process of high temperature to low temperature, so the heat exchanger tube outside wall temperature of heat exchanger is higher than the boiling temperature of water in the heat exchanger tube; Also promptly be higher than the dew-point temperature of flue gas, thereby can avoid dew point corrosion.
Because the temperature that the boiling temperature of water is its saturated vapor pressure when equating with outside pressure, so the boiling point of water follows external pressure relevant, when the suffered pressure increase of water, its elevation of boiling point; When pressure reduced, boiling temperature reduced.Like water saturation vapor (steam) temperature under 1 atmospheric pressure is 100 ℃, but corresponding saturated-steam temperature is 150 ℃ under 6 atmospheric pressures.Based on this principle, as long as control water saturation steam pressure can be controlled the boiling temperature of water.Therefore through utilizing control valve and instrument on the vapor uptake to come the pressure of manual steam regulation online; Relation one to one according to the temperature and pressure of saturated vapor; Thereby control the heat exchange tube wall temperature of fume side indirectly, make it more than dew-point temperature.This is actually the hot rerum natura that fully utilized water and the unidirectional characteristic of heat transfer; Through twice method for indirectly controlling; Promptly once be controlled to be and control saturated vapour pressure through control valve control steam pressure and controlled boiling temperature and be higher than dew-point temperature; Secondary control then is to utilize the one-way of conducting heat, and promptly the outside wall temperature of heat exchanger tube is necessarily greater than the boiling temperature of the water of inside, thereby guarantees that outside wall temperature is higher than dew-point temperature.
In preferred embodiments of the present invention, a kind of method that is used for the preventing corrosion of dew points of flue gas heat exchange device is provided, comprise the steps:
1) jet chimney is provided with flow control valve and the temperature measurement and control instrument that can accept control signal;
2) flow control valve receives the control signal of said temperature measurement and control instrument, regulates aperture automatically, makes vapor (steam) temperature remain on the predefined temperature, and this predefined temperature is higher than the dew-point temperature of flue gas.
Wherein this flue gas heat exchange device can be the two-phase flow heat exchanger, and this jet chimney is the vapor uptake of two-phase flow heat exchanger.
This flow control valve can be pneumatic, fluid power, solenoid valve.
Predefined temperature can be a temperature range.
This temperature measurement and control instrument is the discrete component that has thermometric and temperature controlling function concurrently, or the combination of temperature element and temp-controlling element.
On the condensed water down-comer of two-phase flow heat exchanger, flow control valve can be set.
In another preferred embodiments of the present invention, a kind of method that is used for the preventing corrosion of dew points of flue gas heat exchange device is provided, comprise the steps:
1) flow control valve and temperature measuring equipment are set on jet chimney;
2) according to the temperature measuring equipment temperature displayed, by the manual adjustment flow control valve, make vapor (steam) temperature remain on the predefined temperature, this predefined temperature is higher than the dew-point temperature of flue gas.
Wherein this flue gas heat exchange device can be the two-phase flow heat exchanger, and this jet chimney is the vapor uptake of two-phase flow heat exchanger.
This flow control valve can be manual, pneumatic, fluid power, solenoid valve.
Predefined temperature can be a temperature range.
On the condensed water down-comer of two-phase flow heat exchanger, flow control valve can be set
According to the preventing corrosion of dew points method that is used for the flue gas heat exchange device of the present invention, feasible heat exchanger tube wall temperature with flue gas heat exchange is higher than dew-point temperature all the time, has avoided the generation of dew point corrosion.And, when guaranteeing to avoid dew point corrosion, obtain bigger steam flow and waste heat recovery effect.
Below will combine accompanying drawing that the technique effect of design of the present invention, concrete structure and generation is described further, to understand the object of the invention, characteristic and effect fully.
Description of drawings
Fig. 1 is the sketch map of two phase flow heat transfer device of the prior art.
Fig. 2 is the sketch map of an embodiment of having used the two phase flow heat transfer device of the inventive method.
The specific embodiment
As shown in Figure 2, on the basis of prior art (see figure 1), can be manually or automatically control steam flow and pressure thereby on the vapor uptake of two-phase flow heat exchanger, be provided with steam flow control valve 5 and temperature survey or temperature measurement and control instrument 7.When manually controlling, steam flow control valve 5 can be various control valves such as manual, pneumatic, fluid power, electromagnetism, and device 7 can be simple temperature measuring instrument.When automatic control, steam flow control valve 5 is various control valves such as pneumatic, the hydraulic pressure that can accept control signal, electromagnetism, and temperature measurement and control instrument 7 can also can be the combination of temperature element and temp-controlling element for having the discrete component of thermometric and temperature controlling function concurrently.
When being in preferred automatic control state, at first the control temperature with temperature measurement and control instrument 7 is set on the dew-point temperature of flue gas, and temperature measurement and control instrument 7 is measured the temperature of steam online; When this temperature was lower than design temperature, thermometric and temperature regulating device 7 transmitted control signal to control valve 5 control valve 5 are turned down, thereby the flow of restriction steam improves the pressure of saturated vapor; And because the boiling point of the pressure of saturated vapor and water is corresponding one by one; Therefore the boiling point of water rises, and owing to the one-way of conducting heat, outside wall temperature necessarily is higher than the boiling temperature of water again; And then guaranteed that outside wall temperature is higher than the dew-point temperature of flue gas, thereby avoided dew point corrosion.
Can also the design temperature of temperature measurement and control instrument 7 be controlled within certain temperature range more than the dew point; Working as vapor (steam) temperature like this gos up to design temperature upward in limited time; Temperature measurement and control instrument 7 sends control signal to control valve 5 drives greatly control valve; Can when guaranteeing to avoid dew point corrosion, obtain bigger steam flow and waste heat recovery effect like this.
Under manual state, the temperature that is then recorded according to its temperature measuring equipment by operating personnel manually opens high point minor adjustment valve 5.
On the condensed water down-comer, flow control valve 6 can also be set, with aperture, control the flow of condensed water according to barometric damper.
It is pointed out that the method for dew point corrosion that prevents of the present invention is not only applicable to above-mentioned two phase flow heat transfer device shown in Figure 1, in the heat exchanger of other types,, also can realize the object of the invention as long as adopted twice same control indirectly.As passing through heat pipe and flue gas heat exchange; Thereby the waste heat in the recovery flue gas and producing in the waste heat boiler of steam; On its jet chimney, can adopt according to the method for the invention equally; Promptly control the boiling temperature of water in the boiler heat pipe, make it to be higher than the dew-point temperature of flue gas, thereby avoided dew point corrosion through the flow of control steam.
More than describe preferred embodiment of the present invention in detail.The ordinary skill that should be appreciated that this area need not creative work and just can design according to the present invention make many modifications and variation.Therefore, all technical staff in the art all should be in the determined protection domain by claims under this invention's idea on the basis of existing technology through the available technical scheme of logical analysis, reasoning, or a limited experiment.
Claims (10)
1. method that is used for the preventing corrosion of dew points of flue gas heat exchange device, the water in the heat exchanger tube of said flue gas heat exchange device is heated and produces steam, it is characterized in that, comprises the steps:
1) jet chimney is provided with flow control valve and the temperature measurement and control instrument that can accept control signal;
2) described flow control valve receives the control signal of said temperature measurement and control instrument, regulates aperture automatically, makes vapor (steam) temperature remain on the predefined temperature, and described predefined temperature is higher than the dew-point temperature of flue gas.
2. the method that is used for the preventing corrosion of dew points of flue gas heat exchange device according to claim 1 is characterized in that, described flue gas heat exchange device is the two phase flow heat transfer device, and described jet chimney is the vapor uptake of said two phase flow heat transfer device.
3. according to claim 1 or claim 2 the method for the preventing corrosion of dew points that is used for the flue gas heat exchange device is characterized in that described flow control valve is selected from following group:
Pneumatic operated valve;
The fluid power valve;
Magnetic valve.
4. according to claim 1 or claim 2 the method for the preventing corrosion of dew points that is used for the flue gas heat exchange device is characterized in that wherein said predefined temperature is a temperature range.
5. according to claim 1 or claim 2 the method for the preventing corrosion of dew points that is used for the flue gas heat exchange device is characterized in that wherein said temperature measurement and control instrument is the discrete component that has thermometric and temperature controlling function concurrently, or the combination of temperature element and temp-controlling element.
6. method that is used for the preventing corrosion of dew points of flue gas heat exchange device, the water in the heat exchanger tube in the said flue gas heat exchange device is heated and produces steam, it is characterized in that, comprises the steps:
1) flow control valve and temperature measuring equipment are set on jet chimney;
2) according to described temperature measuring equipment temperature displayed, by the described flow control valve of manual adjustment, make vapor (steam) temperature remain on the predefined temperature, described predefined temperature is higher than the dew-point temperature of flue gas.
7. the method that is used for the preventing corrosion of dew points of flue gas heat exchange device according to claim 6 is characterized in that, described flue gas heat exchange device is the two phase flow heat transfer device, and described jet chimney is the vapor uptake of said two phase flow heat transfer device.
8. like claim 6 or the 7 described methods that are used for the preventing corrosion of dew points of flue gas heat exchange device, it is characterized in that described flow control valve is selected from following group:
Hand-operated valve;
Pneumatic operated valve;
The fluid power valve;
Magnetic valve.
9. like claim 6 or the 7 described methods that are used for the preventing corrosion of dew points of flue gas heat exchange device, it is characterized in that wherein said predefined temperature is a temperature range.
10. like claim 2 or the 7 described methods that are used for the preventing corrosion of dew points of flue gas heat exchange device, it is characterized in that the condensed water down-comer of described two phase flow heat transfer device is provided with flow control valve.
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| CN2011102953215A CN102345997B (en) | 2011-09-29 | 2011-09-29 | Dew point corrosion resistant method for flue gas heat exchanger |
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| CN2011102953215A CN102345997B (en) | 2011-09-29 | 2011-09-29 | Dew point corrosion resistant method for flue gas heat exchanger |
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| CN102345997B true CN102345997B (en) | 2012-11-28 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103196322A (en) * | 2013-04-25 | 2013-07-10 | 安丰宝 | Corrosion prevention method and device of flue gas heat exchanger for kiln |
| CN105277027A (en) * | 2015-11-05 | 2016-01-27 | 吉林省电力科学研究院有限公司 | Phase-change heat exchanger and heat exchange method thereof |
| CN106642456A (en) * | 2016-12-05 | 2017-05-10 | 青岛农业大学 | Natural cold source cold-storage device capable of being quickly assembled and disassembled |
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|---|---|---|---|---|
| CN2417388Y (en) * | 2000-05-12 | 2001-01-31 | 上海华力燃烧设备有限公司 | Non low temp. corrosion type air preheater |
| CN201028790Y (en) * | 2007-04-11 | 2008-02-27 | 南京华电节能环保设备有限公司 | High-performance anti-corrosion air preheater |
| CN101398265A (en) * | 2007-09-28 | 2009-04-01 | 杨本洛 | Composite phase change heat exchanger with medium and low pressure |
| CN201255596Y (en) * | 2008-08-11 | 2009-06-10 | 丹腾空气系统(苏州)有限公司 | Isolation type hot pipe heat exchanger |
| CN102012039A (en) * | 2010-12-22 | 2011-04-13 | 深圳中兴节能环保股份有限公司 | Forced circulation air preheat system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0250020A (en) * | 1988-08-11 | 1990-02-20 | Nkk Corp | Method of operating steam heater for gas preheating |
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- 2011-09-29 CN CN2011102953215A patent/CN102345997B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2417388Y (en) * | 2000-05-12 | 2001-01-31 | 上海华力燃烧设备有限公司 | Non low temp. corrosion type air preheater |
| CN201028790Y (en) * | 2007-04-11 | 2008-02-27 | 南京华电节能环保设备有限公司 | High-performance anti-corrosion air preheater |
| CN101398265A (en) * | 2007-09-28 | 2009-04-01 | 杨本洛 | Composite phase change heat exchanger with medium and low pressure |
| CN201255596Y (en) * | 2008-08-11 | 2009-06-10 | 丹腾空气系统(苏州)有限公司 | Isolation type hot pipe heat exchanger |
| CN102012039A (en) * | 2010-12-22 | 2011-04-13 | 深圳中兴节能环保股份有限公司 | Forced circulation air preheat system |
Non-Patent Citations (1)
| Title |
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| JP平2-50020A 1990.02.20 |
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