CN103307623B

CN103307623B - A kind of sub-control phase-change heat exchange system of Collaborative Control and heat-exchange method

Info

Publication number: CN103307623B
Application number: CN201310187403.7A
Authority: CN
Inventors: 郝江平; 闫润生; 刘新华; 孙广藩; 何宁; 赵康
Original assignee: Shanxi Sanhesheng Industry Technology Co ltd; Institute of Process Engineering of CAS
Current assignee: Shanxi Sanhesheng Industry Technology Co ltd; Institute of Process Engineering of CAS
Priority date: 2013-05-20
Filing date: 2013-05-20
Publication date: 2015-09-30
Anticipated expiration: 2033-05-20
Also published as: CN103307623A

Abstract

The invention discloses a kind of sub-control phase-change heat exchange system and heat-exchange method of Collaborative Control, described system comprises air preheater, high temperature water heater, flue phase-change heat-exchanger, water at low temperature heater, vapour-liquid heat exchanger and air channel heat exchanger, pipeline communication is passed through between each equipment, and some cooling-water temperature sensors and flue-gas temperature sensor are set, described heat-exchange method is the heat-exchange method being carried out Collaborative Control based on above-mentioned heat-exchange system by central control unit.The present invention can adapt to varying environment temperature area, automatically adapt to season, the variation of ambient temperature that causes with climate change round the clock, and automatically adapt to the exhaust gas temperature change that unit load variations causes, automatically adjust waste heat recovery.

Description

A kind of sub-control phase-change heat exchange system of Collaborative Control and heat-exchange method

Technical field

The present invention relates to the flue gas waste heat recovery technical field that safety is controlled, particularly, the present invention relates to a kind of sub-control phase-change heat exchange system and heat-exchange method of Collaborative Control.

Background technology

Tradition phase-change heat-exchange technology emphasizes the uniformity of Cooling and Heat Source phase transition parameter, the degree of supercooling of the phase change medium of thermal source is back in order to reduce low-temperature receiver, the flowing of phase change medium in diabatic process can not have larger pressure drop, has more limitation like this in practical application and performance.Sub-control phase change technique is by the unit that is divided into cold and heat source relatively independent phase-change heat-exchange process unified for tradition and various process, control the phase transition parameter of different units as required respectively, each unit heat exchange regulates voluntarily, and by the degree of supercooling of ad hoc heat exchanger regulating system, namely there is very strong flexibility, also there is very strong integration capability, thus the adaptability of phase-change heat-exchange and economy are greatly improved.

In practical application, thermal source fume afterheat parameter, tail flue gas system and the mode of apparatus arrangement to heat recovery have considerable influence, and utilize the low-temperature receiver parameter of recovery waste heat and the economy of purposes on waste heat recovery to have larger impact, the generating efficiency such as utilizing flue gas in power station boiler waste-heat boiler auxiliary combustion air to improve is significantly higher than the efficiency utilizing fume afterheat to heat steam turbine condensate water to improve, but can make waste heat recycling system fully obtain utilizing also be limited by more multifactor.In order to improve economy and the reliability of the flue gas heat recovery system of different service condition, sub-control phase-change heat exchange system needs different designs.

Sub-control phase-change heat-exchange smoke waste heat utilization system before stresses the heat reclaimed from boiler tail flue gas to be used for heating boiler air feed, but after the wind-warm syndrome entering boiler air preheater improves, flue gas and air reduce at the mean temperature difference of air preheater, if exceed design load, the effect of heat recovery can decline with the rising of environment temperature.For the bootstrap system being in torrid areas, its duration in winter is shorter, and average ambient temperature is higher, the environment four seasons and the temperature difference round the clock less, waste-heat hot blast improves the limited potential of UTILIZATION OF VESIDUAL HEAT IN economy.

Although sub-control phase-change heat-exchange smoke waste heat utilization system before improves the economy of system by combining external water source, but due to set-up mode and the control program restriction of barometric damper, waste heat recycling system can not be effectively made automatically to adapt to change with the operational factor of season, weather and the variation of ambient temperature occurred round the clock and random groups load and fuel change generation, only enhance the security of flue gas waste heat recovery equipment, but exhaust gas temperature does not have, simultaneously as the object automatically controlled, to be thus difficult to obtain best economy; In addition, because system does not control the inlet water temperature that external water source enters high temperature water heater, also just cannot guarantee that high temperature water heater cold end corrosion does not occur.

Summary of the invention

The object of the invention is to, a kind of sub-control phase-change heat exchange system of Collaborative Control is provided, this system can adapt to varying environment temperature area, automatically adapt to season, the variation of ambient temperature that causes with climate change round the clock, and the exhaust gas temperature that adaptation unit load variations causes automatically changes, and automatically adjusts waste heat recovery.

For achieving the above object, present invention employs following technical scheme:

A sub-control phase-change heat exchange system for Collaborative Control, described system comprises air preheater 3, flue phase-change heat-exchanger 5, water at low temperature heater 8, vapour-liquid heat exchanger 12 and air channel heat exchanger 17;

Described air preheater 3, flue phase-change heat-exchanger 5 are successively set on flue 1 by flue gas flow direction;

The exhanst gas outlet of described chimney heat exchanger 5 is arranged a flue-gas temperature sensor 6;

Described first water pipe 20 arranges the first cooling-water temperature sensor 18, for detecting the leaving water temperature of water at low temperature heater 8;

Described flue phase-change heat-exchanger 5 is communicated with vapour-liquid heat exchanger 12 by the second water pipe 22, described flue phase-change heat-exchanger 5 is arranged an output main steam range 23, described output main steam range 23 is divided into the first branch road 24, second branch road 25 and the 3rd branch road 26, first branch road 24 accesses water at low temperature heater 8, second branch road 25 accesses vapour-liquid heat exchanger 12, and the 3rd branch road 26 accesses air channel heat exchanger 17;

Described second water pipe 23 arranges the second water intaking valve 13, described first branch road 24 is arranged a water at low temperature heater for steam control valve 7, described 3rd branch road 26 is arranged an air channel heat exchanger for steam control valve 14;

Described water at low temperature heater 8 enters water tank 16 by the first outlet pipe 27 water delivery, described vapour-liquid heat exchanger 12 enters water tank 16 by the second outlet pipe 28 water delivery, described air channel heat exchanger 17 enters water tank 16 by the 3rd outlet pipe 29 water delivery, described water tank 16 enters vapour-liquid heat exchanger 12 by the 4th outlet pipe 30 water delivery, and the 4th outlet pipe arranges a water pump 15;

Described water at low temperature heater 8 is connected with external water pipe road 11, and external water pipe road 11 is arranged the first water intaking valve 10;

Described air channel heat exchanger 17 is delivered air in air preheater 3 by air channel 2.

Further, described system also comprises a high temperature water heater 4, described high temperature water heater 4 is arranged on the flue 1 before or after air preheater 3 by flue gas flow direction, described high temperature water heater 4 is communicated with water at low temperature heater 8 by the first water pipe 20, described high temperature water heater 4 is also arranged an outlet pipe 21, described outlet pipe 21 is arranged the second cooling-water temperature sensor 19, for detecting the leaving water temperature of high temperature water heater 4; External water pipe road 11 before the first water intaking valve 10 picks out a bypass water pipe 31, bypass water pipe 31 accesses the first water pipe 20, bypass water pipe 31 is also arranged a water pipe bypass valve 9.

Described high temperature water heater 4 can be arranged on the flue 1 before or after air preheater 3 by flue gas flow direction.Also can be arranged in the bypass flue of air preheater 3.

In described air preheater 3, high temperature water heater 4, flue phase-change heat-exchanger 5, optional flue 1 between the two arranges deduster, also other equipment can be set, but the context that aforementioned device presses flue gas flow direction is constant.

3rd branch road 26 is connected to air vent pipework, needs in the winter time can supplement external steam when strengthening air preheat.

Another object of the present invention is, provides a kind of heat-exchange method of the sub-control phase-change heat exchange system based on above-mentioned Collaborative Control, said method comprising the steps of:

Flue phase-change heat-exchanger 5 absorbs the flue gas heat flowing through flue 1, the water being entered its inside by the second water pipe 22 is evaporated to steam, described steam exports by exporting main steam range 23, and respectively by the first branch road 24, second branch road 25 and the 3rd branch road 26 vapour side steam supply to water at low temperature heater 8, vapour-liquid heat exchanger 12 and air channel heat exchanger 17;

Enter the steam of water at low temperature heater 8 to the heat transfer water being entered water at low temperature heater 8 by external water pipe road 11, the steam entering vapour-liquid heat exchanger 12 is to the condensed water heat transfer being entered vapour-liquid heat exchanger 12 by the 4th outlet pipe 30, and the steam entering air channel heat exchanger 17 conducts heat to the cold wind of side, air channel heat exchanger 17 air channel;

Above-mentioned three road steam are all released latent heat and are condensed into water in respective heat exchanger, water tank 16 is flowed into through the first outlet pipe 27, second outlet pipe 28 and the 3rd outlet pipe 29, condensed water in water tank 16 boosts through water pump 15, vapour-liquid heat exchanger 12 is entered through the 4th outlet pipe 30, enter flue phase-change heat-exchanger 5 through the second water pipe 22 after being heated, continuation absorption flue gas heat is evaporated to steam and starts new heat transfer cycle;

Outer water receiving through water at low temperature heater 8 heat after, for user;

Or outer water receiving, after water at low temperature heater 8 and high temperature water heater 4 heat, exports from outlet pipe 21, and for user;

Wherein, the aperture of air channel heat exchanger confession steam control valve 14 is controlled by the phase transition parameter (temperature and pressure when undergoing phase transition) in flue phase-change heat-exchanger 5; Water at low temperature heater supplies the aperture of steam control valve 7 to be controlled by the measured value of the flue-gas temperature sensor 6 that flue phase-change heat-exchanger 5 exports; The aperture of the first water intaking valve 10 is controlled by the measured value of the first cooling-water temperature sensor 18; The aperture of water pipe bypass valve 9 is controlled by the measured value of the second cooling-water temperature sensor 19 and the measured value of flue-gas temperature sensor 6;

Described air channel heat exchanger carries out Collaborative Control adjustment by central control unit according to the phase transition parameter in flue phase-change heat-exchanger 5, the measured value of flue-gas temperature sensor 6, first cooling-water temperature sensor 18, second cooling-water temperature sensor 19 and the comparing result of setting value for the aperture of steam control valve 7, first water intaking valve 10, water pipe bypass valve 9 for steam control valve 14, water at low temperature heater.

In the present invention, flue-gas temperature sensor 6, water at low temperature heater for steam control valve 7, air channel heat exchange for the Collaborative Control step of steam control valve 14 and the first water intaking valve 10 are:

When environment temperature raises or unit load raising, the measured value of flue-gas temperature sensor 6 is greater than setting value, then water at low temperature heater is opened greatly for the aperture of steam control valve 7, and the phase transition parameter in flue phase-change heat-exchanger 5 reduces, and water at low temperature heater 8 exports water temperature raising simultaneously; Air channel heat exchanger turns down for the aperture of steam control valve 14 thereupon, and the aperture of the first water intaking valve 10 is opened greatly;

When environment temperature reduces or unit load reduction, the measured value of flue-gas temperature sensor 6 is less than setting value, then water at low temperature heater reduces for the aperture of steam control valve 7, and the phase transition parameter in flue phase-change heat-exchanger 5 raises, and water at low temperature heater 8 exports water temperature minimizing simultaneously; Air channel heat exchanger is opened greatly for the aperture of steam control valve 14 thereupon, and the aperture of the first water intaking valve 10 diminishes.

Heat-exchange method of the present invention also comprises the rate-determining steps of water pipe bypass valve 9:

When the measured value of the first cooling-water temperature sensor 19 and the measured value of flue-gas temperature sensor 6 are higher than setting value, open water pipe bypass valve 9, increase the external discharge of high temperature water heater 4, to reduce output water temperature and flue phase-change heat-exchanger 5 exit gas temperature of outlet pipe 21 simultaneously.

In the present invention, the second water intaking valve 13 is responsible for the water yield that control enters flue phase-change heat-exchanger 5; Air channel heat exchanger can control for steam control valve 14 quantity of steam entering air channel heat exchanger 17; Water at low temperature heater can control for steam control valve 7 quantity of steam entering water at low temperature heater 8.Air channel heat exchanger supplies the outlet vapor flow of steam control valve 7 all controlled tobacco curing road phase-change heat-exchanger 5 for steam control valve 14 and water at low temperature heater, thus the steam flow control valve controlling flue phase-change heat-exchanger 5 phase transition parameter is, therefore, when the steam production of flue phase-change heat-exchanger 5 is constant, one when opening large, for keeping stablizing another and then turning down of phase transition parameter, these two kinds of steam flow control valves oppositely can regulate, carry out Collaborative Control, when one of them controls phase transition parameter, another then controls exhaust gas temperature;

The Collaborative Control scheme of steam control valve 7 is supplied to be described in detail air channel heat exchanger for steam control valve 14 and water at low temperature heater below.

Collaborative Control scheme one

Water at low temperature heater controls according to the deviation of the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 and flue phase-change heat-exchanger 5 exit gas temperature setting value automatically for the aperture of steam control valve 7, when the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 is greater than flue phase-change heat-exchanger 5 exit gas temperature setting value, then water at low temperature heater is opened greatly for the aperture of steam control valve 7, meanwhile, the phase transition parameter in flue phase-change heat-exchanger 5 is reduced.When the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 is less than flue phase-change heat-exchanger 5 exit gas temperature setting value, then water at low temperature heater turns down for the aperture of steam control valve 7, meanwhile, the phase transition parameter in flue phase-change heat-exchanger 5 is increased.

Air channel heat exchanger controls according to the deviation of the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 with the phase transition parameter setting value in flue phase-change heat-exchanger 5 automatically for the aperture of steam control valve 14, when the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 is less than setting value, then air channel heat exchanger turns down for the aperture of steam control valve 14.When the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 is greater than setting value, then air channel heat exchanger is opened greatly for the aperture of steam control valve 14.

Collaborative Control scheme two

Air channel heat exchanger controls according to the deviation of the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 and flue phase-change heat-exchanger 5 exit gas temperature setting value automatically for the aperture of steam control valve 14, when the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 is less than flue phase-change heat-exchanger 5 exit gas temperature setting value, then air channel heat exchanger is opened greatly for the aperture of steam control valve 14, meanwhile, the phase transition parameter (temperature and pressure) in flue phase-change heat-exchanger 5 is reduced.When the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 is greater than in flue phase-change heat-exchanger 5 exit gas temperature setting value, then air channel heat exchanger turns down for the aperture of steam control valve 14, meanwhile, the phase transition parameter (temperature and pressure) in flue phase-change heat-exchanger 5 is increased..

Water at low temperature heater controls according to the deviation of the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 with the phase transition parameter setting value in flue phase-change heat-exchanger 5 automatically for the aperture of steam control valve 7, when the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 is less than setting value, then water at low temperature heater turns down for the aperture of steam control valve 7.When the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 is greater than setting value, then water at low temperature heater is opened greatly for the aperture of steam control valve 7.

In the present invention, phase transition parameter in exhaust gas temperature and flue phase-change heat-exchanger or the wall temperature setting value of flue phase-change heat-exchanger are generally higher than flue gas acid dew point and leave certain allowance, but when flue phase-change heat-exchanger adopts anti-corrosion material, the wall temperature of exhaust gas temperature and flue phase-change heat-exchanger can be allowed a little less than flue gas acid dew point, lighter to the harm of equipment and system.

Flue phase-change heat-exchanger 5 exit gas temperature setting value is higher than flue gas acid dew point-20 DEG C ~ and 60 DEG C, and automatically can regulate according to the change of flue gas acid dew point, when having that in the flue gas of corresponding relation, sulfur content is than setting value height with flue gas acid dew point, then according to the controlling calculation of controller corresponding raising flue phase-change heat-exchanger 5 exit gas temperature setting value, vice versa.

The setting value of the phase transition parameter in flue phase-change heat-exchanger 5 is higher than flue gas acid dew point-20 DEG C ~ and 30 DEG C, and automatically can regulate according to the change of flue gas acid dew point, when having that in the flue gas of corresponding relation, sulfur content is than setting value height with flue gas acid dew point, then according to the setting value of the phase transition parameter in the controlling calculation of controller corresponding raising flue phase-change heat-exchanger 5, vice versa.

Namely this regulative mode ensure that fully effectively utilizing of waste heat, in turn ensure that flue phase-change heat-exchanger 5 alleviates or cold end corrosion do not occur.Described process, can guarantee flue phase-change heat-exchanger 5 wall temperature measurement accurately in situation, and the wall temperature of flue phase-change heat-exchanger 5 can be adopted to substitute phase transition parameter in flue phase-change heat-exchanger 5 as controling parameters.

State Collaborative Control scheme before execution for the moment, the first water intaking valve 10 and water pipe bypass valve 9 can have multiple control program and aforementioned Collaborative Control scheme phase coordinated.Below the Collaborative Control scheme of the first water intaking valve 10 and water pipe bypass valve 9 is described in detail.

First water intaking valve 10 and water pipe bypass valve 9 Collaborative Control scheme one

The coolant-temperature gage that the aperture of the first water intaking valve 10 is measured by the first cooling-water temperature sensor 18 of water at low temperature heater 8 exit portion controls, when the coolant-temperature gage that the first cooling-water temperature sensor 18 is measured is lower than setting value, then turn down the first water intaking valve 10, to make the discharge reduction entering water at low temperature heater 8, thus the inlet water temperature of high temperature water heater 4 and respective settings value are consistent, when the coolant-temperature gage that the first cooling-water temperature sensor 18 is measured is higher than setting value, then open large first water intaking valve 10, increase to make the water yield entering water at low temperature heater 8, thus the inlet water temperature of high temperature water heater 4 and respective settings value are consistent,

Water at low temperature heater 8 export the setting value of water temperature higher than flue gas acid dew point-40 DEG C ~ 30 DEG C, and automatically can regulate according to the change of flue gas acid dew point, when having that in the flue gas of corresponding relation, sulfur content is than setting value height with flue gas acid dew point, then export the setting value of water temperature according to the controlling calculation of controller corresponding raising water at low temperature heater 8, vice versa.

Namely this regulative mode ensure that fully effectively utilizing of waste heat, in turn ensure that high temperature water heater 4 does not occur or alleviates cold end corrosion.Described process, guaranteeing high temperature water heater 4 wall temperature measurement accurately in situation, can adopt high temperature water heater 4 wall temperature to substitute water at low temperature heater 8 and export water temperature as controling parameters.

Second cooling-water temperature sensor 19 exports water temperature for monitoring high temperature water heater 4, exports water temperature and flue phase-change heat-exchanger 5 exit gas temperature with auxiliary adjustment high temperature water heater 4.When the measured value of the second cooling-water temperature sensor 19 or flue phase-change heat-exchanger 5 exit gas temperature sensor 6 measured value are higher than respective settings value, aperture by driving big pipe bypass valve 9 increases the water at low temperature flow entering high temperature water heater 4, thus reduce the measured value of the second cooling-water temperature sensor 19 or the deviation of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 measured value and setting value, when the measured value of the second cooling-water temperature sensor 19 or flue phase-change heat-exchanger 5 exit gas temperature sensor 6 measured value are lower than respective settings value, aperture by turning down water pipe bypass valve 9 reduces the water at low temperature flow entering high temperature water heater 4, thus reduce the measured value of the second cooling-water temperature sensor 19 or the deviation of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 measured value and setting value.

The Collaborative Control scheme two of the first water intaking valve 10 and water pipe bypass valve 9

The coolant-temperature gage that the aperture of the first water intaking valve 10 is measured by the second cooling-water temperature sensor 19 controls, when the coolant-temperature gage that the second cooling-water temperature sensor 19 is measured is lower than setting value, then turn down the first water intaking valve 10, to make the low temperature discharge reduction entering high temperature water heater 4, thus the outlet water temperature of high temperature water heater 4 and respective settings value are consistent, when the coolant-temperature gage that the second cooling-water temperature sensor 19 is measured is higher than setting value, then open large first water intaking valve 10, increase to make the low temperature water yield entering high temperature water heater 4, thus the outlet water temperature of high temperature water heater 4 and respective settings value are consistent.

Second cooling-water temperature sensor 19, for monitoring the outlet water temperature of high temperature water heater 4, can guarantee economy and the security of heat recovery;

The aperture of water pipe bypass valve 9 regulates according to the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 or the measured value of the first cooling-water temperature sensor 18.The aperture of big pipe bypass valve 9 can be opened by automatic or manual when the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 increases, to reduce the water temperature entering high temperature water heater 4, thus reduce flue phase-change heat-exchanger 5 exit gas temperature, the aperture of water pipe bypass valve 9 can be turned down by automatic or manual when the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 reduces, to increase the water temperature entering high temperature water heater 4, thus raise flue phase-change heat-exchanger 5 exit gas temperature.

When the measured value of the first cooling-water temperature sensor 18 is lower than setting value, then automatic or manual turns down the aperture of water pipe bypass valve 9, and when the measured value of the first cooling-water temperature sensor 18 is higher than setting value, then automatic or manual opens the aperture of big pipe bypass valve 9.

The another Collaborative Control scheme of the overall simplification of present system: air channel heat exchanger controls the phase transition parameter in flue phase-change heat-exchanger 5 for steam control valve 14, exhaust gas temperature controls the first water intaking valve 10, can realize like this, to reduce exhaust gas temperature for while target, ensure that flue phase-change heat-exchanger 5 cold end corrosion does not occur;

The aperture of the first water intaking valve 10 regulates according to the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6.Automatically the aperture of large first water intaking valve 10 can be opened when the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 increases, to reduce the water temperature entering high temperature water heater 4, thus reduce flue phase-change heat-exchanger 5 exit gas temperature, add steam consumption quantity in water at low temperature heater 8 simultaneously, phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 declines, automatically the aperture of the first water intaking valve 10 can be turned down when the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 reduces, to increase the water temperature entering high temperature water heater 4, thus increase flue phase-change heat-exchanger 5 exit gas temperature, decrease steam consumption quantity in water at low temperature heater 8 simultaneously, phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 raises.

Air channel heat exchanger controls according to the deviation of the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 with setting value automatically for the aperture of steam control valve 14, when the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 is less than setting value, then air channel heat exchanger turns down for the aperture of steam control valve 14, when the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 is greater than setting value, then air channel heat exchanger is opened greatly for the aperture of steam control valve 14.

Water at low temperature heater can Non-follow control for steam control valve 7 and water pipe bypass valve 9, distribute at the heating load of water at low temperature heater 8 and high temperature water heater 4 to regulate outer water receiving, regulate heating load to distribute by it can revise the impact that operational factor changes and system error is brought, add ability and the precision of system fading margin.When driving large water at low temperature heater for steam control valve 7 or water pipe bypass valve 9, under other condition is constant, the heat that flue gas in flue 1 passes to water at low temperature heater 8 China and foreign countries water receiving through flue phase-change heat-exchanger 5 increases, and the heat being directly passed to high temperature water heater 4 China and foreign countries water receiving reduces, when turning down water at low temperature heater for steam control valve 7 or water pipe bypass valve 9, under other condition is constant, the heat that flue gas in flue 1 passes to water at low temperature heater 8 China and foreign countries water receiving through flue phase-change heat-exchanger 5 reduces, and the heat being directly passed to high temperature water heater 4 China and foreign countries water receiving increases.

The caloric receptivity increasing water at low temperature heater 8 China and foreign countries water receiving can improve the temperature of the outer water receiving entering high temperature water heater 4, alleviates the cold end corrosion harm of high temperature water heater 4; Otherwise, within the scope of the cold end corrosion that cold end corrosion or permission do not occur high temperature water heater 4, the caloric receptivity reducing water at low temperature heater 8 China and foreign countries water receiving can reduce the temperature of the outer water receiving entering high temperature water heater 4, thus increase flue gas to the heat output of high temperature water heater 4, the exhaust gas temperature that flue phase-change heat-exchanger 5 exports can be reduced, improve waste heat recovery benefit.

A simplification Collaborative Control scheme again of the overall simplification of present system: air channel heat exchanger controls the phase transition parameter in flue phase-change heat-exchanger 5 for steam control valve 14, high temperature water heater 4 outlet temperature carrys out regulable control first water intaking valve 10, can realize like this, the heat exchange ratio of water at low temperature heater 8, high temperature water heater 4 and flue phase-change heat-exchanger 5 is changed, to reduce exhaust gas temperature by controlling external discharge.When raising along with exhaust gas temperature, when the measured value of the second cooling-water temperature sensor 19 is higher than setting value, control to open large first water intaking valve 10 to increase flow and the caloric receptivity of outer water receiving, thus reduce exhaust gas temperature, add the steam consumption quantity in water at low temperature heater 8, the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 declines simultaneously; When the phase transition parameter in flue phase-change heat-exchanger 5 is less than setting value, then air channel heat exchanger turns down for the aperture of steam control valve 14.When reducing along with exhaust gas temperature, when the measured value of the second cooling-water temperature sensor 19 is lower than setting value, control to turn down the first water intaking valve 10 to reduce flow and the caloric receptivity of outer water receiving, thus increase exhaust gas temperature, decrease the steam consumption quantity in water at low temperature heater 8, the phase transition parameter (phase transition temperature or pressure phase transition) in flue phase-change heat-exchanger 5 raises simultaneously; When the phase transition parameter in flue phase-change heat-exchanger 5 is greater than setting value, then air channel heat exchanger is opened greatly for the aperture of steam control valve 14.

As mentioned above,

When the air themperature being entered air channel 2 by environment increases, by the impact that the heat transfer temperature difference of flue gas and air reduces, in air preheater 3, air is reduced by the temperature rise of heating, exhaust gas temperature after air preheater 3 raises, high temperature water heater 4 all strengthens with the heat exchange amount of flue phase-change heat-exchanger 5, the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 and the first cooling-water temperature sensor 18, the measured value of the second cooling-water temperature sensor 19 also improves, thereupon, the control procedure of aforementioned above several Collaborative Control scheme finally all makes the quantity of steam ratio entered in air channel heat exchanger 17 reduce, to reduce the air themperature (also namely reducing the air themperature entering air preheater 3) that air channel heat exchanger 17 exports, thus increase the heat transfer temperature difference of flue gas and air in air preheater 3, air is increased by the temperature rise of heating, exhaust gas temperature after air preheater reduces, reduce the loss of smoke discharging residual heat.

Otherwise, when the air themperature being entered air channel 2 by environment reduces, by the impact that the heat transfer temperature difference of flue gas and air increases, in air preheater 3, air is increased by the temperature rise of heating, exhaust gas temperature after air preheater 3 reduces, high temperature water heater 4 all reduces with the heat exchange amount of flue phase-change heat-exchanger 5, the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 and the first cooling-water temperature sensor 18, the measured value of the second cooling-water temperature sensor 19 also reduces, thereupon, the control procedure of aforementioned above several Collaborative Control scheme finally all makes the quantity of steam ratio entered in air channel heat exchanger 17 increase, to improve the air themperature (also namely reducing the air themperature entering air preheater) that air channel heat exchanger 17 exports, thus be reduced in the heat transfer temperature difference of flue gas and air in air preheater 3, air is reduced by the temperature rise of heating, exhaust gas temperature after air preheater 5 improves, avoid or alleviate the cold end corrosion of air preheater and subsequent heating surface,

Heat-exchange system of the present invention and heat-exchange method carry out Collaborative Control to heat exchanger wall temperature in exhaust gas temperature, condensing water temperature and flue, the area of varying environment temperature can be adapted to, automatically adapt to season, the variation of ambient temperature that causes with climate change round the clock, and the exhaust gas temperature that adaptation unit load variations causes automatically changes, the Land use systems of automatic adjustment waste heat recovery, under guaranteeing heating surface safety, first waste heat is used for adding hot-air, simultaneously exhaust gas temperature is all the time under controlled, reaches Best Economy and the security of heat recovery.

Accompanying drawing explanation

Fig. 1 is the structural representation of the sub-control phase-change heat exchange system of Collaborative Control of the present invention;

Wherein, 1, flue; 2, air channel; 3, air preheater; 4, high temperature water heater; 5, flue phase-change heat-exchanger; 6, flue-gas temperature sensor; 7, water at low temperature heater is for steam control valve; 8, water at low temperature heater; 9, water pipe bypass valve; 10, the first water intaking valve; 11, external water pipe road; 12, vapour-liquid heat exchanger; 13, the second water intaking valve; 14, air channel heat exchanger is for steam control valve; 15, water pump; 16, water tank; 17, air channel heat exchanger; 18, the first cooling-water temperature sensor; 19, the second cooling-water temperature sensor; 20, the first water pipe; 21, outlet pipe; 22, the second water pipe; 23, main steam range is exported; 24, the first branch road; 25, the second branch road; 26, the 3rd branch road; 27, the first outlet pipe; 28, the second outlet pipe; 29, the 3rd outlet pipe; 30, the 4th outlet pipe; 31, bypass water pipe.

Detailed description of the invention

With the drawings and specific embodiments, the present invention is further detailed explanation below.

Embodiment 1

As shown in Figure 1, a kind of sub-control phase-change heat exchange system of Collaborative Control, described system comprises air preheater 3, high temperature water heater 4, flue phase-change heat-exchanger 5, water at low temperature heater 8, vapour-liquid heat exchanger 12 and air channel heat exchanger 17;

Described air preheater 3, high temperature water heater 4, flue phase-change heat-exchanger 5 are successively set on flue 1;

Described high temperature water heater 4 is communicated with water at low temperature heater 8 by the first water pipe 20, described high temperature water heater 4 is also arranged an outlet pipe 21, the exhanst gas outlet of described chimney heat exchanger 5 is arranged a flue-gas temperature sensor 6;

Described first water pipe 20 arranging the first cooling-water temperature sensor 18, for detecting the leaving water temperature of water at low temperature heater 8, described outlet pipe 21 being arranged the second cooling-water temperature sensor 19, for detecting the leaving water temperature of high temperature water heater 4;

Described water at low temperature heater 8 is connected with external water pipe road 11, and external water pipe road 11 is arranged the first water intaking valve 10, external water pipe road 11 before the first water intaking valve 10 picks out a bypass water pipe 31, bypass water pipe 31 accesses the first water pipe 20, bypass water pipe 31 is also arranged a water pipe bypass valve 9;

Based on a heat-exchange method for the sub-control phase-change heat exchange system of above-mentioned Collaborative Control, said method comprising the steps of:

From outer water receiving after water at low temperature heater 8 and high temperature water heater 4 heat, export from outlet pipe 21, and for user;

The Collaborative Control step of the heat exchanger confession steam control valve 14 of air channel described in the present embodiment and water at low temperature heater confession steam control valve 7 is:

Water at low temperature heater controls according to the measured value of flue-gas temperature sensor 6 and the deviation of setting value automatically for the aperture of steam control valve 7, when the measured value of flue-gas temperature sensor 6 is greater than setting value, then water at low temperature heater is opened greatly for the aperture of steam control valve 7, meanwhile, the phase transition parameter in flue phase-change heat-exchanger 5 is reduced;

Air channel heat exchanger controls according to the deviation of the phase transition parameter in flue phase-change heat-exchanger 5 and setting value automatically for the aperture of steam control valve 14, when the phase transition parameter in flue phase-change heat-exchanger 5 is less than setting value, then air channel heat exchanger turns down for the aperture of steam control valve 14.

Described in the present embodiment, the Collaborative Control step of the first water intaking valve 10 and the first cooling-water temperature sensor 18 is:

The coolant-temperature gage that the aperture of the first water intaking valve 10 is measured by the first cooling-water temperature sensor 18 controls, when the coolant-temperature gage that the first cooling-water temperature sensor 18 is measured is lower than setting value, then turn down the first water intaking valve 10, to make the discharge reduction entering water at low temperature heater 8, when the coolant-temperature gage that the first cooling-water temperature sensor 18 is measured is higher than setting value, then open large first water intaking valve 10, increase to make the water yield entering water at low temperature heater 8;

Water at low temperature heater 8 export the setting value of water temperature higher than flue gas acid dew point-40 DEG C ~ 30 DEG C, and automatically can regulate according to the change of flue gas acid dew point, when having that in the flue gas of corresponding relation, sulfur content is than setting value height with flue gas acid dew point, then export the setting value of water temperature according to the controlling calculation of controller corresponding raising water at low temperature heater 8.

The sensor of flue-gas temperature described in the present embodiment 6, water at low temperature heater for steam control valve 7, air channel heat exchange for the Collaborative Control step of steam control valve 14 and the first water intaking valve 10 are:

The Collaborative Control step of the bypass valve of water pipe described in the present embodiment 9 and the first water intaking valve 10 is:

The coolant-temperature gage that the aperture of the first water intaking valve 10 is measured by the first cooling-water temperature sensor 18 controls, when the coolant-temperature gage that the first cooling-water temperature sensor 18 is measured is lower than setting value, then turn down the first water intaking valve 10, to make the discharge reduction entering water at low temperature heater 8, thus the inlet water temperature of high temperature water heater 4 and respective settings value are consistent;

Water at low temperature heater 8 export the setting value of water temperature higher than flue gas acid dew point-40 DEG C ~ 30 DEG C, and automatically can regulate according to the change of flue gas acid dew point, when having that in the flue gas of corresponding relation, sulfur content is than setting value height with flue gas acid dew point, then export the setting value of water temperature according to the controlling calculation of controller corresponding raising water at low temperature heater 8;

Second cooling-water temperature sensor 19 exports water temperature for monitoring high temperature water heater 4, water temperature and flue phase-change heat-exchanger 5 exit gas temperature is exported with auxiliary adjustment high temperature water heater 4, when the measured value of the second cooling-water temperature sensor 19 or flue-gas temperature sensor 6 measured value are higher than respective settings value, aperture by driving big pipe bypass valve 9 increases the water at low temperature flow entering high temperature water heater 4, thus reduces the deviation of the measured value of the second cooling-water temperature sensor 19 and the deviation of setting value or flue-gas temperature sensor 6 measured value and setting value.

The Collaborative Control step of the bypass valve of water pipe described in the present embodiment 9 and the first water intaking valve 10 can also be:

The coolant-temperature gage that the aperture of the first water intaking valve 10 is measured by the second cooling-water temperature sensor 19 controls, when the coolant-temperature gage that the second cooling-water temperature sensor 19 is measured is lower than setting value, then turn down the first water intaking valve 10, to make the low temperature discharge reduction entering high temperature water heater 4, thus the outlet water temperature of high temperature water heater 4 and respective settings value are consistent;

The aperture of water pipe bypass valve 9 regulates according to the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 or the measured value of the first cooling-water temperature sensor 18;

The aperture of big pipe bypass valve 9 can be opened by automatic or manual when the measured value of flue phase-change heat-exchanger 5 exit gas temperature sensor 6 increases, to reduce the water temperature entering high temperature water heater 4, thus reduce flue phase-change heat-exchanger 5 exit gas temperature;

When the measured value of the first cooling-water temperature sensor 18 is lower than setting value, then automatic or manual turns down the aperture of water pipe bypass valve 9.

When flue phase-change heat-exchanger 5 exit gas temperature sensor 6 measured value is all the time lower than setting value, then whole waste heats of off-gas recovery are all for heating boiler air feed, and the efficiency of heat recovery reaches the highest.

Embodiment 2

From outer water receiving after water at low temperature heater 8 heats, for user;

Wherein, the aperture of air channel heat exchanger confession steam control valve 14 is controlled by the phase transition parameter (temperature and pressure when undergoing phase transition) in flue phase-change heat-exchanger 5; Water at low temperature heater supplies the aperture of steam control valve 7 to be controlled by the measured value of the flue-gas temperature sensor 6 that flue phase-change heat-exchanger 5 exports; The aperture of the first water intaking valve 10 is controlled by the measured value of the first cooling-water temperature sensor 18;

Described air channel heat exchanger carries out Collaborative Control adjustment by central control unit according to the phase transition parameter in flue phase-change heat-exchanger 5, the measured value of flue-gas temperature sensor 6, first cooling-water temperature sensor 18 and the comparing result of setting value for the aperture of steam control valve 7, first water intaking valve 10 for steam control valve 14, water at low temperature heater.

Air channel heat exchanger controls according to the measured value of flue-gas temperature sensor 6 and the deviation of setting value automatically for the aperture of steam control valve 14, when measured value is less than setting value, then air channel heat exchanger is opened greatly for the aperture of steam control valve 14, meanwhile, reduces the phase transition parameter in flue phase-change heat-exchanger 5;

Water at low temperature heater controls according to the deviation of the phase transition parameter in flue phase-change heat-exchanger 5 and setting value automatically for the aperture of steam control valve 7, when the phase transition parameter in flue phase-change heat-exchanger 5 is less than setting value, then water at low temperature heater turns down for the aperture of steam control valve 7.

Claims

1. the sub-control phase-change heat exchange system of a Collaborative Control, it is characterized in that, described system comprises air preheater (3), flue phase-change heat-exchanger (5), water at low temperature heater (8), vapour-liquid heat exchanger (12) and air channel heat exchanger (17), and the first water pipe (20);

Described air preheater (3) and flue phase-change heat-exchanger (5) are successively set on flue (1) by flue gas flow direction;

The exhanst gas outlet of described chimney heat exchanger (5) is arranged a flue-gas temperature sensor (6);

Described first water pipe (20) arranges the first cooling-water temperature sensor (18), for detecting the leaving water temperature of water at low temperature heater (8);

Described flue phase-change heat-exchanger (5) is communicated with vapour-liquid heat exchanger (12) by the second water pipe (22), described flue phase-change heat-exchanger (5) is arranged an output main steam range (23), described output main steam range (23) is divided into the first branch road (24), the second branch road (25) and the 3rd branch road (26), first branch road (24) access water at low temperature heater (8), second branch road (25) access vapour-liquid heat exchanger (12), the 3rd branch road (26) access air channel heat exchanger (17);

Described second water pipe (22) arranges the second water intaking valve (13), described first branch road (24) is arranged a water at low temperature heater for steam control valve (7), described 3rd branch road (26) is arranged an air channel heat exchanger for steam control valve (14);

Described water at low temperature heater (8) enters water tank (16) by the first outlet pipe (27) water delivery, described vapour-liquid heat exchanger (12) enters water tank (16) by the second outlet pipe (28) water delivery, described air channel heat exchanger (17) enters water tank (16) by the 3rd outlet pipe (29) water delivery, described water tank (16) enters vapour-liquid heat exchanger (12) by the 4th outlet pipe (30) water delivery, and the 4th outlet pipe arranges a water pump (15);

Described water at low temperature heater (8) is connected with external water pipe road (11), and external water pipe road (11) arrange the first water intaking valve (10);

Air enters into air preheater (3) through described air channel heat exchanger (17) be arranged on air channel (2).

2. the sub-control phase-change heat exchange system of Collaborative Control according to claim 1, it is characterized in that, described system also comprises a high temperature water heater (4), described high temperature water heater (4) is arranged on the flue (1) before or after air preheater (3) by flue gas flow direction, described high temperature water heater (4) is communicated with water at low temperature heater (8) by the first water pipe (20), described high temperature water heater (4) is also arranged an outlet pipe (21), described outlet pipe (21) is arranged the second cooling-water temperature sensor (19), for detecting the leaving water temperature of high temperature water heater (4),

The external water pipe road (11) that first water intaking valve (10) is front picks out a bypass water pipe (31), bypass water pipe (31) accesses the first water pipe (20), bypass water pipe (31) is also arranged a water pipe bypass valve (9).

3. the sub-control phase-change heat exchange system of Collaborative Control according to claim 2, it is characterized in that, in described air preheater (3), high temperature water heater (4), flue phase-change heat-exchanger (5), optional flue (1) between the two arranges deduster.

4. the sub-control phase-change heat exchange system of Collaborative Control according to claim 1 and 2, is characterized in that, is connected to air vent pipework at the 3rd branch road (26), supplements external steam for needing winter when strengthening air preheat.

5., based on a heat-exchange method for the sub-control phase-change heat exchange system of Collaborative Control described in claim 1, said method comprising the steps of:

Flue phase-change heat-exchanger (5) absorbs the flue gas heat flowing through flue (1), the water being entered its inside by the second water pipe (22) is evaporated to steam, described steam exports by exporting main steam range (23), and respectively by the first branch road (24), the second branch road (25) and the 3rd branch road (26) the vapour side steam supply to water at low temperature heater (8), vapour-liquid heat exchanger (12) and air channel heat exchanger (17);

Enter the steam of water at low temperature heater (8) to the external heat transfer water being entered water at low temperature heater (8) by external water pipe road (11), the steam entering vapour-liquid heat exchanger (12) is to the condensed water heat transfer being entered vapour-liquid heat exchanger (12) by the 4th outlet pipe (30), and the steam entering air channel heat exchanger (17) conducts heat to the cold wind of air channel heat exchanger (17) side, air channel;

Above-mentioned three road steam are released latent heat respectively and are condensed into water in respective heat exchanger, water tank (16) is flowed into through the first outlet pipe (27), the second outlet pipe (28) and the 3rd outlet pipe (29), condensed water in water tank (16) boosts through water pump (15), vapour-liquid heat exchanger (12) is entered through the 4th outlet pipe (30), enter flue phase-change heat-exchanger (5) through the second water pipe (22) after being heated, continuation absorption flue gas heat is evaporated to steam and starts new heat transfer cycle;

The outer water receiving entered from external water pipe road (11) after water at low temperature heater (8) heating, for user;

Wherein, the aperture of air channel heat exchanger for steam control valve (14) is controlled according to the phase transition parameter in flue phase-change heat-exchanger (5); Measured value according to flue-gas temperature sensor (6) controls the aperture of water at low temperature heater for steam control valve (7); Measured value according to the first cooling-water temperature sensor (18) controls the aperture of the first water intaking valve (10);

Described air channel heat exchanger carries out Collaborative Control adjustment by control unit according to the phase transition parameter in flue phase-change heat-exchanger (5), flue-gas temperature sensor (6), the measured value of the first cooling-water temperature sensor (18) and the comparing result of setting value for the aperture of steam control valve (7), the first water intaking valve (10) for steam control valve (14), water at low temperature heater.

6., based on a heat-exchange method for the sub-control phase-change heat exchange system of Collaborative Control described in Claims 2 or 3, said method comprising the steps of:

The outer water receiving entered from external water pipe road (11), after water at low temperature heater (8) and high temperature water heater (4) heating, exports, for user from outlet pipe (21);

Wherein, the aperture of air channel heat exchanger for steam control valve (14) is controlled according to the phase transition parameter in flue phase-change heat-exchanger (5); Measured value according to flue-gas temperature sensor (6) controls the aperture of water at low temperature heater for steam control valve (7); Measured value according to the first cooling-water temperature sensor (18) controls the aperture of the first water intaking valve (10); The aperture of water pipe bypass valve (9) is controlled according to the measured value of the second cooling-water temperature sensor (19) and the measured value of flue-gas temperature sensor (6);

Described air channel heat exchanger carries out Collaborative Control adjustment by control unit according to the phase transition parameter in flue phase-change heat-exchanger (5), flue-gas temperature sensor (6), the first cooling-water temperature sensor (18), the measured value of the second cooling-water temperature sensor (19) and the comparing result of setting value for the aperture of steam control valve (7), the first water intaking valve (10), water pipe bypass valve (9) for steam control valve (14), water at low temperature heater.

7. the heat-exchange method according to claim 5 or 6, is characterized in that, the Collaborative Control step of described air channel heat exchanger confession steam control valve (14) and water at low temperature heater confession steam control valve (7) is:

Water at low temperature heater controls according to the measured value of flue-gas temperature sensor (6) and the deviation of setting value automatically for the aperture of steam control valve (7), when the measured value of flue-gas temperature sensor (6) is greater than setting value, then water at low temperature heater is opened greatly for the aperture of steam control valve (7), simultaneously, reduce the phase transition parameter in flue phase-change heat-exchanger (5), when the measured value of flue-gas temperature sensor (6) is less than in setting value, then water at low temperature heater turns down for the aperture of steam control valve (7), simultaneously, increase the phase transition parameter in flue phase-change heat-exchanger (5),

Air channel heat exchanger controls according to the deviation of the phase transition parameter in flue phase-change heat-exchanger (5) and setting value automatically for the aperture of steam control valve (14), when the phase transition parameter in flue phase-change heat-exchanger (5) is less than setting value, then air channel heat exchanger turns down for the aperture of steam control valve (14), when the phase transition parameter in flue phase-change heat-exchanger (5) is greater than setting value, then air channel heat exchanger is opened greatly for the aperture of steam control valve (14).

8. the heat-exchange method according to claim 5 or 6, is characterized in that, the Collaborative Control step of described air channel heat exchanger confession steam control valve (14) and water at low temperature heater confession steam control valve (7) is:

Air channel heat exchanger controls according to the measured value of flue-gas temperature sensor (6) and the deviation of setting value automatically for the aperture of steam control valve (14), when measured value is less than setting value, then air channel heat exchanger is opened greatly for the aperture of steam control valve (14), simultaneously, reduce the phase transition parameter in flue phase-change heat-exchanger (5), when measured value is greater than setting value, then air channel heat exchanger turns down for the aperture of steam control valve (14), meanwhile, the phase transition parameter in flue phase-change heat-exchanger (5) is increased;

Water at low temperature heater controls according to the deviation of the phase transition parameter in flue phase-change heat-exchanger (5) and setting value automatically for the aperture of steam control valve (7), when the phase transition parameter in flue phase-change heat-exchanger (5) is less than setting value, then water at low temperature heater turns down for the aperture of steam control valve (7), when the phase transition parameter in flue phase-change heat-exchanger (5) is greater than setting value, then water at low temperature heater is opened greatly for the aperture of steam control valve (7).

9. the heat-exchange method according to claim 5 or 6, is characterized in that, the rate-determining steps of described first water intaking valve (10) and the first cooling-water temperature sensor (18) is:

The coolant-temperature gage that the aperture of the first water intaking valve (10) is measured by the first cooling-water temperature sensor (18) controls, when the coolant-temperature gage that the first cooling-water temperature sensor (18) is measured is lower than setting value, then turn down the first water intaking valve (10), to make the discharge reduction entering water at low temperature heater (8), when the coolant-temperature gage that the first cooling-water temperature sensor (18) is measured is higher than setting value, then open large first water intaking valve (10), increase to make the water yield entering water at low temperature heater (8);

Water at low temperature heater (8) outlet water temperature setting value higher than flue gas acid dew point-40 DEG C ~ 30 DEG C, and automatically can regulate according to the change of flue gas acid dew point, when having that in the flue gas of corresponding relation, sulfur content is than setting value height with flue gas acid dew point, then according to the setting value of the controlling calculation of controller corresponding raising water at low temperature heater (8) outlet water temperature.

10. the heat-exchange method according to claim 5 or 6, it is characterized in that, described flue-gas temperature sensor (6), water at low temperature heater for steam control valve (7), air channel heat exchange for the Collaborative Control step of steam control valve (14) and the first water intaking valve (10) are:

When environment temperature raises or unit load raising, the measured value of flue-gas temperature sensor (6) is greater than setting value, then water at low temperature heater is opened greatly for the aperture of steam control valve (7), phase transition parameter in flue phase-change heat-exchanger (5) reduces, and the water temperature of water at low temperature heater (8) outlet simultaneously improves; Air channel heat exchanger turns down for the aperture of steam control valve (14) thereupon, and the aperture of the first water intaking valve (10) is opened greatly;

When environment temperature reduces or unit load reduction, the measured value of flue-gas temperature sensor (6) is less than setting value, then water at low temperature heater reduces for the aperture of steam control valve (7), phase transition parameter in flue phase-change heat-exchanger (5) raises, and the water temperature of water at low temperature heater (8) outlet simultaneously reduces; Air channel heat exchanger is opened greatly for the aperture of steam control valve (14) thereupon, and the aperture of the first water intaking valve (10) diminishes.

11. heat-exchange methods according to claim 6, is characterized in that, the Collaborative Control step of described water pipe bypass valve (9) and the first water intaking valve (10) is:

The coolant-temperature gage that the aperture of the first water intaking valve (10) is measured by the first cooling-water temperature sensor (18) controls, when the coolant-temperature gage that the first cooling-water temperature sensor (18) is measured is lower than setting value, then turn down the first water intaking valve (10), to make the discharge reduction entering water at low temperature heater (8), thus the inlet water temperature of high temperature water heater (4) and respective settings value are consistent;

Water at low temperature heater (8) outlet water temperature setting value higher than flue gas acid dew point-40 DEG C ~ 30 DEG C, and automatically can regulate according to the change of flue gas acid dew point, when having that in the flue gas of corresponding relation, sulfur content is than setting value height with flue gas acid dew point, then according to the setting value of the controlling calculation of controller corresponding raising water at low temperature heater (8) outlet water temperature;

Second cooling-water temperature sensor (19) is for monitoring high temperature water heater (4) outlet water temperature, with auxiliary adjustment high temperature water heater (4) outlet water temperature and flue phase-change heat-exchanger (5) exit gas temperature, when the measured value of the second cooling-water temperature sensor (19) or flue-gas temperature sensor (6) measured value are higher than respective settings value, aperture by driving big pipe bypass valve (9) increases the water at low temperature flow entering high temperature water heater (4), thus reduce measured value and the deviation of setting value or the deviation of flue-gas temperature sensor (6) measured value and setting value of the second cooling-water temperature sensor (19).

12. heat-exchange methods according to claim 6, is characterized in that, the Collaborative Control step of described water pipe bypass valve (9) and the first water intaking valve (10) is:

The coolant-temperature gage that the aperture of the first water intaking valve (10) is measured by the second cooling-water temperature sensor (19) controls, when the coolant-temperature gage that the second cooling-water temperature sensor (19) is measured is lower than setting value, then turn down the first water intaking valve (10), to make the low temperature discharge reduction entering high temperature water heater (4), thus the outlet water temperature of high temperature water heater (4) and respective settings value are consistent;

The aperture of water pipe bypass valve (9) regulates according to the measured value of the measured value of flue phase-change heat-exchanger (5) exit gas temperature sensor (6) or the first cooling-water temperature sensor (18);

The aperture of big pipe bypass valve (9) can be opened by automatic or manual when the measured value of flue phase-change heat-exchanger (5) exit gas temperature sensor (6) increases, to reduce the water temperature entering high temperature water heater (4), thus reduce flue phase-change heat-exchanger (5) exit gas temperature;

When the measured value of the first cooling-water temperature sensor (18) is lower than setting value, then automatic or manual turns down the aperture of water pipe bypass valve (9).