CN113252844A - Method for detecting scale formation of heat exchange part of gas water heater and gas water heater - Google Patents

Method for detecting scale formation of heat exchange part of gas water heater and gas water heater Download PDF

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CN113252844A
CN113252844A CN202110420839.0A CN202110420839A CN113252844A CN 113252844 A CN113252844 A CN 113252844A CN 202110420839 A CN202110420839 A CN 202110420839A CN 113252844 A CN113252844 A CN 113252844A
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gas
water heater
oxygen content
gas water
heat exchange
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CN113252844B (en
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陈阳坚
王建军
陈跃华
刘应斌
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Midea Group Co Ltd
Wuhu Midea Kitchen and Bath Appliances Manufacturing Co Ltd
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Midea Group Co Ltd
Wuhu Midea Kitchen and Bath Appliances Manufacturing Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00—Details
    • F24H9/20—Arrangement or mounting of control or safety devices
    • F24H9/2007—Arrangement or mounting of control or safety devices for water heaters
    • F24H9/2035—Arrangement or mounting of control or safety devices for water heaters using fluid fuel
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
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    • G01D21/02—Measuring two or more variables by means not covered by a single other subclass
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]

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  • Instantaneous Water Boilers, Portable Hot-Water Supply Apparatuses, And Control Of Portable Hot-Water Supply Apparatuses (AREA)
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Abstract

The invention relates to a gas water heater, and discloses a method for detecting scale formation of a heat exchange part of the gas water heater, which comprises the following steps: 1) detecting the actual heat output quantity (W) of the gas water heater; 2) detecting the oxygen content (e) of the flue gas discharged by the gas water heater; 3) adjusting the combustion state of the fuel gas according to the oxygen content (e) of the flue gas; 4) detecting the temperature (Te) of the flue gas discharged by the gas water heater; 5) and judging the actual heat exchange efficiency of the gas water heater according to the flue gas temperature (Te) and judging the scale formation state of the heat exchange component according to the actual heat exchange efficiency. The method can accurately judge the scale formation condition of the heat exchange component. The invention also discloses a gas water heater using the method.

Description

Method for detecting scale formation of heat exchange part of gas water heater and gas water heater
Technical Field
The invention relates to a gas water heater, in particular to a method for detecting scale formation of a heat exchange part of the gas water heater. In addition, the invention also relates to a gas water heater.
Background
The existing gas water heater is pursuing high energy efficiency more and more. In order to realize better energy-saving effect, a condensing gas water heater is recently appeared, cold water entering the water heater is preheated by a mode of arranging a condensing heat exchanger on a high-temperature flue gas discharge channel, heat in high-temperature flue gas is fully utilized, and the heat efficiency of the gas water heater is greatly improved. But the condensing heat exchanger also produces a large amount of condensed water and NO in the flue gas in the heat exchange processx、SO2When dissolved in the condensed water, acid ions are formed, so that the pH value of the condensed water is reduced to 4.0-6.0, and a strong corrosion effect is generated on the heat exchanger.
In order to improve the corrosion resistance of the heat exchanger and ensure the service life and the heat exchange capability of the heat exchanger on the basis of lower cost, more and more gas water heaters adopt stainless steel heat exchangers to replace oxygen-free copper heat exchangers.
Due to the presence of Ca in the water stream2+、Mg2+、CO3 2-、OH-The scale is easily deposited on the inner surface of the heat exchange tube of the heat exchanger under a high-temperature environment to form scale, and the use of the stainless steel heat exchanger is more likely to cause the deposition of the scale. The formation of water scale reduces the heat conduction performance of the heat exchange tube, so that the heat exchange efficiency of the heat exchanger is seriously reduced, and the energy waste is caused. In addition, when the scale formation is serious, the heat exchange pipe is easy to block, the flow rate of the heat exchange pipe is reduced, and the water yield of the water heater is reduced. Moreover, the scaling can also cause the local temperature of the heat exchange tube to be overhigh, cause the corrosion perforation of the heat exchange tube and cause water leakage.
In the existing heat exchanger scale formation alarm method, the scale formation degree of the heat exchanger is judged according to the ratio of the actual output power of the water heater to the designed output power. However, the actual output power of the gas water heater is greatly influenced by the combustion state of the gas and the water yield, the scaling condition of the heat exchanger cannot be objectively reflected, and misjudgment is easy to occur.
Disclosure of Invention
The invention aims to provide a method for detecting scale formation of a heat exchange part of a gas water heater, which can accurately judge the scale formation condition of the heat exchange part.
The invention further aims to solve the technical problem of providing the gas water heater, which can ensure the heat exchange effect and prolong the service life.
In order to solve the technical problem, the invention provides a method for detecting scale formation of a heat exchange part of a gas water heater, which comprises the following steps: 1) detecting the actual heat output quantity of the gas water heater; 2) detecting the oxygen content of the flue gas discharged by the gas water heater; 3) adjusting the combustion state of the fuel gas to a set combustion state according to the oxygen content of the flue gas under the actual heat output quantity; 4) detecting the temperature of the flue gas discharged by the gas water heater in the set combustion state; 5) and judging the actual heat exchange efficiency of the gas water heater according to the flue gas temperature, and judging the scale formation state of the heat exchange component according to the actual heat exchange efficiency.
Preferably, in step 1), the actual heat output is obtained by detecting the water flow, the inlet water temperature and the outlet water temperature of the gas water heater; in step 3), the combustion state of the gas is adjusted by adjusting the air supply amount of the gas water heater or adjusting the ratio of air mixed in the gas. In the preferred technical scheme, the heat absorbed by the hot water output from the gas water heater, namely the actual heat output quantity of the gas water heater, can be conveniently obtained through the water flow of the gas water heater and the temperature difference of the inlet water and the outlet water. By adjusting the air supply in the gas water heater, the amount of oxygen supporting the combustion of the gas can be adjusted. By adjusting the proportion of air mixed in the gas of the fully premixed gas water heater, the amount of oxygen provided for supporting the combustion of the gas can also be adjusted. The amount of oxygen provided directly affects the combustion efficiency of the fuel gas and also affects the oxygen content in the flue gas generated by the combustion of the fuel gas.
Further preferably, in step 3), setting an upper normal oxygen content limit and a lower normal oxygen content limit of the discharged flue gas corresponding to different actual heat output quantities, and when the oxygen content of the flue gas is greater than the upper normal oxygen content limit, reducing the air supply quantity of the gas water heater or reducing the proportion of air mixed in the gas; and when the oxygen content of the flue gas is smaller than the lower limit of the normal oxygen content, increasing the air supply quantity of the gas water heater or increasing the proportion of air mixed in the gas. In the preferred technical scheme, because the gas can consume part of oxygen in the air during normal combustion, part of oxygen which does not participate in the combustion of the gas remains in the exhaust smoke. The oxygen content in the discharged flue gas reflects the sufficiency of the air supply when the gas is combusted. When the gas is normally combusted, the oxygen content in the exhausted smoke can be kept in a certain level, and along with the difference of the actual heat output quantity of the gas water heater, the oxygen content level in the exhausted smoke can be different when the gas is normally combusted. Setting the upper limit of the oxygen content level as the upper limit of the normal oxygen content of the exhausted smoke, setting the lower limit of the level as the lower limit of the normal oxygen content of the exhausted smoke, and when the oxygen content of the smoke is greater than the upper limit of the normal oxygen content, indicating that the air supply is excessive, so that the air supply needs to be reduced; when the oxygen content of the flue gas is lower than the lower limit of the normal oxygen content, the air supply is insufficient, and therefore the air supply needs to be increased. Therefore, the gas in the gas water heater can be ensured to be in a normal combustion state.
Further, in the step 3), a safety oxygen content upper limit and a safety oxygen content lower limit of the discharged flue gas are further set, and when the oxygen content of the flue gas is greater than the safety oxygen content upper limit or is less than the safety oxygen content lower limit, alarm information is sent out, and the gas supply of the gas water heater is stopped. In the preferred technical scheme, when the oxygen content of the flue gas is higher than the upper limit of the safe oxygen content, it indicates that the air supply of the gas water heater is extremely high, and the too fast air flow easily causes the flame temperature reduction during the combustion of the gas, generates the flame leaving phenomenon, can cause the generation of a large amount of CO, and easily causes the safety risk. And when the oxygen content of the flue gas is less than the lower limit of the safe oxygen content, the air supply of the gas water heater is very little, the gas flow rate is slow, and the back fire is easily generated by combustion along the supply path, so that the safety risk is caused. Under the condition, the safety alarm information is sent out, the use of the gas water heater is forcibly stopped, and the use safety of the gas water heater can be ensured.
Preferably, the upper limit of the normal oxygen content and the lower limit of the normal oxygen content corresponding to different actual heat output quantities are obtained by the control system of the gas water heater in a self-learning manner before the gas water heater leaves the factory. Through the optimal technical scheme, the upper limit and the lower limit of the normal oxygen content corresponding to a plurality of different actual heat output quantities can be automatically obtained, and the obtained upper limit and the obtained lower limit of the normal oxygen content can be more suitable for different actual conditions of the gas water heater.
Preferably, in step 5), the actual heat exchange efficiency is judged according to the actual heat output and the flue gas temperature. In the preferred technical scheme, the actual heat output quantity reflects the heat obtained by water flow after heat exchange of the heat exchange part of the gas water heater, namely the heat exchanged by the heat exchange part; the temperature of the flue gas reflects the waste heat which is not absorbed by water flow and is generated after the gas is combusted, namely the heat which is not exchanged by the heat exchange part. The actual heat exchange efficiency of the heat exchange component can be conveniently judged through the actual heat output quantity and the flue gas temperature.
Further preferably, in step 5), a normal flue gas temperature upper limit corresponding to different actual heat output amounts is set, and when the flue gas temperature is greater than the normal flue gas temperature upper limit, scale formation of the heat exchange component is judged, and scale formation alarm information is given. In the preferred technical scheme, the gas water heater has different normal flue gas temperatures at different actual heat output quantities, and the higher the flue gas temperature is, the worse the actual heat exchange efficiency of the heat exchange part is displayed under the same actual heat output quantity. And the poor direct performance that is heat transfer part incrustation scale of heat transfer part's heat exchange efficiency, when flue gas temperature exceeded normal flue gas temperature upper limit, the incrustation scale that found in the explanation heat transfer part has influenced heat transfer part's normal heat transfer, needs clear away the processing. At the moment, scale formation alarm information is given, and a user is reminded of cleaning scales.
Further, in the step 5), a safety flue gas temperature upper limit is further set, when the flue gas temperature is higher than the safety flue gas temperature upper limit, it is judged that the scale formation of the heat exchange component is serious, a warning message of the serious scale formation is given, and the gas supply of the gas water heater is stopped. Through this preferred technical scheme, can be serious at heat transfer part incrustation scale, give alarm information when heat transfer part heat exchange efficiency is extremely poor to force the use that stops gas heater, prevent gas heater's damage or cause the incident.
Preferably, the upper limit of the normal flue gas temperature corresponding to different actual heat output is obtained by a control system of the gas water heater in a self-learning manner before leaving a factory. Through this preferred technical scheme, can obtain the normal flue gas temperature upper limit corresponding with a plurality of different actual heating output volume automatically to, the normal flue gas temperature upper limit that obtains also can more be fit for different gas heater actual conditions.
The invention provides another scale formation detection method for a heat exchange part of a gas water heater, which comprises the following steps: 1) detecting the actual heat output quantity of the gas water heater; 2) detecting the oxygen content of the flue gas discharged by the gas water heater; 3) adjusting the combustion state of the fuel gas to a set combustion state according to the oxygen content of the flue gas under the actual heat output quantity; 4) and judging the actual heat exchange efficiency of the gas water heater according to the actual heat output under the set combustion state, and judging the scale formation state of the heat exchange component according to the actual heat output.
Preferably, in step 1), the actual heat output is obtained through the water flow, the inlet water temperature and the outlet water temperature of the gas water heater; in step 3), the combustion state of the gas is adjusted to the set combustion state by adjusting the air supply amount of the gas water heater or adjusting the ratio of air mixed in the gas. In the preferred technical scheme, the heat absorbed by the hot water output from the gas water heater, namely the actual heat output quantity of the gas water heater, can be conveniently obtained through the water flow of the gas water heater and the temperature difference of the inlet water and the outlet water. By adjusting the air supply in the gas water heater, the amount of oxygen supporting the combustion of the gas can be adjusted. By adjusting the proportion of air mixed in the gas of the fully premixed gas water heater, the amount of oxygen provided for supporting the combustion of the gas can also be adjusted. The amount of oxygen provided directly affects the combustion efficiency of the fuel gas and also affects the oxygen content in the flue gas generated by the combustion of the fuel gas.
Further preferably, an upper limit and a lower limit of the normal oxygen content of the discharged flue gas corresponding to different actual heat output quantities are set in step 3), and when the oxygen content of the flue gas is greater than the upper limit of the normal oxygen content, the air supply quantity of the gas water heater is reduced, or the proportion of air mixed in the gas is reduced; and when the oxygen content of the flue gas is smaller than the lower limit of the normal oxygen content, increasing the air supply quantity of the gas water heater or increasing the proportion of air mixed in the gas. In the preferred technical scheme, because the gas can consume part of oxygen in the air during normal combustion, part of oxygen which does not participate in the combustion of the gas remains in the exhaust smoke. The oxygen content in the discharged flue gas reflects the sufficiency of the air supply when the gas is combusted. When the gas is normally combusted, the oxygen content in the exhausted smoke can be kept in a certain level, and along with the difference of the actual heat output quantity of the gas water heater, the oxygen content level in the exhausted smoke can be different when the gas is normally combusted. Setting the upper limit of the oxygen content level as the upper limit of the normal oxygen content of the exhausted smoke, setting the lower limit of the level as the lower limit of the normal oxygen content of the exhausted smoke, and when the oxygen content of the smoke is greater than the upper limit of the normal oxygen content, indicating that the air supply is excessive, so that the air supply needs to be reduced; when the oxygen content of the flue gas is lower than the lower limit of the normal oxygen content, the air supply is insufficient, and therefore the air supply needs to be increased. Therefore, the gas in the gas water heater can be ensured to be in a normal combustion state.
Further, a safe oxygen content upper limit and a safe oxygen content lower limit of the discharged smoke are also set in the step 3), and when the oxygen content of the smoke is larger than the safe oxygen content upper limit or smaller than the safe oxygen content lower limit, alarm information is sent out, and the gas supply of the gas water heater is stopped. In the preferred technical scheme, when the oxygen content of the flue gas is higher than the upper limit of the safe oxygen content, it indicates that the air supply of the gas water heater is extremely high, and the too fast air flow easily causes the flame temperature reduction during the combustion of the gas, generates the flame leaving phenomenon, can cause the generation of a large amount of CO, and easily causes the safety risk. And when the oxygen content of the flue gas is less than the lower limit of the safe oxygen content, the air supply of the gas water heater is very little, the gas flow rate is slow, and the back fire is easily generated by combustion along the supply path, so that the safety risk is caused. Under the condition, the safety alarm information is sent out, the use of the gas water heater is forcibly stopped, and the use safety of the gas water heater can be ensured.
Preferably, the upper limit of the normal oxygen content and the lower limit of the normal oxygen content corresponding to different actual heat output quantities are obtained by the control system of the gas water heater in a self-learning manner before the gas water heater leaves the factory. Through the optimal technical scheme, the upper limit and the lower limit of the normal oxygen content corresponding to a plurality of different actual heat output quantities can be automatically obtained, and the obtained upper limit and the obtained lower limit of the normal oxygen content can be more suitable for different actual conditions of the gas water heater.
Preferably, in step 5), the actual heat exchange efficiency is judged according to the actual heat output quantity and the heat input parameter; the heat input parameter is the rotating speed of a fan or a secondary pressure sequence of the rotating speed of the fan and fuel gas. In the preferred technical scheme, the actual heat output quantity of the gas water heater can be influenced by the working state of the gas water heater, and the actual heat exchange efficiency of the gas water heater can be more accurately judged according to the actual heat output quantity under a certain heat input parameter. In gas water heaters with different gas combustion modes, heat input is usually adjusted by adjusting the rotating speed of a fan or adjusting the rotating speed of the fan and the corresponding secondary pressure of gas at the same time. Therefore, the heat input quantity of the gas water heater can be well reflected by acquiring the rotating speed of the fan in the control system of the gas water heater or the secondary pressure sequence of the gas of the rotating speed of the fan. According to the actual heat output quantity under a certain heat input quantity, the actual heat exchange efficiency of the gas water heater can be accurately judged.
Further preferably, in step 5), a normal actual heat output lower limit corresponding to different heat input parameters is set, and when the actual heat output is smaller than the normal actual heat output lower limit, scale formation of the heat exchange component is judged, and scale formation warning information is given. In the preferred technical solution, the gas water heater has different actual heat output amounts when operating under different heat input parameters. The worse the actual heat exchange efficiency of the heat exchange member, the lower the actual heat output under the same heat input parameters. And the poor direct performance that is heat transfer part incrustation scale of heat transfer part of heat transfer efficiency, when actual heat output volume is less than normal actual heat output lower limit, explains that incrustation scale in the heat transfer part has influenced heat transfer part's normal heat transfer, needs clear away the processing. At the moment, scale formation alarm information is given, and a user is reminded of cleaning scales.
Further, a safe actual heat output lower limit is also set in the step 5), when the actual heat output is smaller than the safe actual heat output lower limit, the scale formation of the heat exchange part is judged to be serious, a warning message of the serious scale formation is given, and the gas supply of the gas water heater is stopped. Through this preferred technical scheme, can judge that heat transfer part knot incrustation scale is serious when actual heat output volume descends seriously, and heat transfer part heat exchange efficiency is extremely poor. At the moment, the system gives alarm information and forcibly stops the use of the gas water heater, so that the heat exchange component can be prevented from being damaged due to serious uneven heating, and even safety accidents are caused.
Preferably, the lower limit of the normal actual heat output corresponding to different heat input parameters is obtained by the control system of the gas water heater in a self-learning manner before leaving the factory. Through this preferred technical scheme, can obtain the normal flue gas temperature upper limit corresponding with a plurality of different actual heating output volume automatically to, the normal flue gas temperature upper limit that obtains also can more be fit for different gas heater actual conditions.
The third aspect of the invention provides a gas water heater, which comprises a heat exchange part scale formation detection system, wherein the heat exchange part scale formation detection system adopts the gas water heater heat exchange part scale formation detection method provided by the first aspect or the second aspect of the invention to detect scale.
According to the technical scheme, the scale formation detection method for the heat exchange part of the gas water heater disclosed by the invention can be used for obtaining the working state of the gas water heater by detecting the actual heat output. Through the flue gas oxygen content that detects the burning flue gas, can learn the gas combustion state of gas heater under specific operating condition to adjust the gas combustion state, be in normal combustion state with the assurance gas. Through the detection to the gas heater exhaust gas temperature of flue gas, can learn not by how much of rivers absorptive heat when the gas burning to judge gas heater's actual heat exchange efficiency. Or the actual heat output quantity of the gas water heater in a set combustion state is used for pushing the heat quantity absorbed by the water flow heat exchange, so that the actual heat exchange efficiency of the gas water heater is judged. The actual heat exchange efficiency of the gas water heater is directly related to the scale formation degree of the heat exchange component, so that the scale formation degree of the heat exchange component can be judged. According to the method, when the actual heat exchange efficiency of the gas water heater is judged, the gas is ensured to be in a normal combustion state, and the influence of the combustion state of the gas on the actual heat production is eliminated; the actual heat exchange efficiency is judged by combining the actual heat output quantity of the gas water heater, and the influence of different water yields on the heat exchange efficiency is eliminated, so that the misjudgment of scale formation of the heat exchange component can be prevented, and the detection result is more accurate. The gas water heater can accurately judge the scale formation state of the heat exchange component due to the use of the scale formation detection method of the heat exchange component of the gas water heater, so as to treat the scale when necessary and ensure the heat exchange efficiency of the heat exchange component. Can discover the serious state of incrustation scale of the heat exchange component in time and ensure the use safety.
Other technical features and advantages of the present invention will be further described in the following detailed description.
Drawings
FIG. 1 is a block flow diagram of one embodiment of a method for detecting scale formation in a heat exchange unit of a gas water heater in accordance with the present invention;
FIG. 2 is a block flow diagram of another embodiment of the scale formation detection method for the heat exchange part of the gas water heater of the present invention;
FIG. 3 is a schematic block diagram of one embodiment of the gas water heater of the present invention;
FIG. 4 is a schematic diagram of the heat exchange components in one embodiment of the gas water heater of the present invention.
Description of the reference numerals
11 water inlet 12 water proportional valve
13 heat exchanger 131 combustion chamber
132 heat exchange tube 133 heat exchange fin
134 smoke baffle 14 water outlet
21 air inlet 22 gas proportional valve
23 air inlet 24 blower
25 premixer 26 burner
27 outlet 31 water flow sensor
32 inlet water temperature sensor and 33 outlet water temperature sensor
34 flue gas temperature sensor and 35 flue gas oxygen content sensor
36 controller
Detailed Description
In the present invention, an orientation or positional relationship indicated by the use of directional words such as "upper and lower" is an orientation or positional relationship of the described device or member based on the actual use, unless otherwise specified.
In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted" and "connected" are to be interpreted broadly, for example, the term "connected" may be a fixed connection, a detachable connection, or an integral connection; either directly or indirectly through intervening media, either internally or in any combination thereof. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, and it is to be understood that the detailed description is provided for purposes of illustration and explanation and is not intended to limit the scope of the invention.
As shown in fig. 1, an embodiment of the method for detecting scale formation on a heat exchange component of a gas water heater of the present invention comprises the following steps:
1) the actual heating output W of the gas water heater is detected. The actual heat output quantity W of the water heater reflects the working state of the gas water heater, namely the quantity of gas combusted by the gas water heater and the temperature and flow conditions of output hot water. The gas heater's flue gas exhaust condition is relevant with its operating condition, through the actual heating output W that detects gas heater, can distinguish the flue gas exhaust condition under the different operating condition, prevents because of the influence of operating condition difference to the testing result.
2) And detecting the oxygen content e of the flue gas discharged by the gas water heater. The oxygen content e of the flue gas reflects the air supply amount during the combustion of the gas in the gas water heater and also reflects the full degree of the combustion of the gas. Through the flue gas oxygen content e in the detection exhaust flue gas, can learn the gas combustion state of gas heater during operation to make the judgement to whether heat transfer component knot incrustation scale go on under the normal combustion state of gas, prevent the influence of gas combustion state to the judged result. Generally, the oxygen content e of the flue gas can be detected by arranging an oxygen sensor at the smoke outlet of the gas water heater.
3) And adjusting the combustion state of the fuel gas according to the oxygen content e of the flue gas. Because the oxygen content e of the flue gas reflects the combustion state of the fuel gas, the combustion state of the fuel gas can be known according to the oxygen content e of the flue gas. Therefore, the combustion state of the fuel gas under different actual heat output quantities can be adjusted to the set combustion state according to the values of the oxygen content e of the fuel gas under different actual heat output quantities. Specifically, the combustion state of the gas can be adjusted by adjusting the supply amount of the gas, the supply amount of air for combustion supporting gas combustion, the air flow rate of gas supply, and the like. However, when the gas is operated, a user has specific requirements on the flow rate and the temperature of hot water output by the water heater, and therefore, the adjustment of the flue gas state needs to be comprehensively adjusted according to the requirements of the user. If the air flow speed is increased, the proportion of the fuel gas in the air flow needs to be reduced in order not to increase the water temperature.
4) And detecting the smoke temperature Te of the smoke discharged by the gas water heater. The flue gas temperature Te represents the amount of heat that is released to the air in a gas water heater without being absorbed by the water flow, and a condensing water heater increases the thermal efficiency by absorbing more heat from the flue gas. The more heat generated by the combustion of the gas is absorbed by the water flow, the lower the flue gas temperature Te. The absorption degree of the water flow to the heat generated by the combustion of the gas can be judged by checking the temperature Te of the flue gas discharged by the water heater. The smoke temperature Te can be detected by a temperature sensor at the smoke outlet of the gas water heater. Under certain heat exchange efficiency, different combustion states of gas can influence the flue gas temperature Te of the flue gas discharged by the gas water heater and influence the judgment result of the heat exchange efficiency. Through adjusting the combustion state of gas to setting for the combustion state, can get rid of the gas combustion state to flue gas temperature Te's influence, improve the accuracy of heat exchange efficiency judgement result.
5) And judging the actual heat exchange efficiency of the gas water heater according to the flue gas temperature Te, and judging the scale formation state of the heat exchange component according to the actual heat exchange efficiency. The flue gas temperature Te reflects the amount of heat which is not absorbed by the heat exchange of water flow in the heat generated by the combustion of the gas, and the flue gas temperature Te is increased, which shows that the heat transferred to the water flow through the heat exchange part is reduced, and the actual heat exchange efficiency of the gas water heater is reduced; on the contrary, the decrease of the flue gas temperature Te indicates that the heat quantity of the feed water flow transferred by the heat exchange component is increased and the actual heat exchange efficiency of the gas water heater is increased, so that the flue gas temperature Te can reflect the actual heat exchange efficiency of the heat exchange component of the gas water heater. The actual heat exchange efficiency is determined by the heat conduction performance, the water flow and the water temperature of the heat exchange component, and the water flow and the water temperature are closely related to the actual heat output quantity W, so that the heat conduction performance of the heat exchange component can be judged through the actual heat exchange efficiency under a certain actual heat output quantity W. And the heat conductivity of the heat exchange component in use reflects the scale formation degree of the heat exchange component, so that the scale formation state of the heat exchange component can be judged through the flue gas temperature Te and the actual heat output quantity W.
In some embodiments of the method of the present invention, the actual heating output W of the gas water heater is obtained by detecting the water flow Q, the inlet water temperature T0 and the outlet water temperature Tt of the gas water heater. A water flow sensor may be provided in the water inlet path of the gas water heater to detect the water flow Q, a temperature sensor may be provided to detect the water inlet temperature T0, and a temperature sensor may be provided in the water outlet path of the gas water heater to detect the water temperature Tt. The actual heating output W is calculated by the formula W ═ Q × (Tt-T0). The calculation of the actual heating output W may be performed by a controller provided in the gas water heater.
In step 3), the combustion state of the gas may be adjusted by adjusting the air supply amount of the gas water heater or by adjusting the ratio of air mixed into the gas, depending on the type of the gas water heater. In particular, the speed of rotation of the fan supplying the gas water heater with air can be adjusted, thereby adjusting the amount of air supplied to the gas water heater combustion chamber, or to the premixer. By adjusting the amount of air supplied, the amount of oxygen in the burner can be adjusted, thereby adjusting the combustion state of the gas. The combustion state of the gas can be reflected through the oxygen content e of the flue gas, so that the combustion state of the gas can be adjusted according to the oxygen content e of the flue gas, and the gas in the gas water heater is always in a normal set combustion state.
In some embodiments of the method of the invention, the control system of the gas water heater is provided with upper limits e of the normal oxygen content of the exhaust fumes corresponding to different actual heat output quantities WmaxAnd lower limit of normal oxygen content emin. When the detected oxygen content e of the flue gas is at the upper limit e of the normal oxygen contentmaxAnd lower limit of normal oxygen content eminWhen the combustion state of the fuel gas is within the range, the combustion state of the fuel gas is in a normal set combustion state; when the oxygen content e of the flue gas is more than emaxWhen the combustion of the fuel gas is carried out, the oxygen supply is excessive, at the moment, the air supply can be reduced by reducing the rotating speed of the fan, the air supply quantity in the combustion chamber is reduced, or the proportion of premixed air in the fuel gas is reduced, so that the combustion state of the fuel gas is recovered to a set combustion state, and the oxygen content e of the flue gas is recovered to a normal level; when the oxygen content e of the flue gas is less than eminWhen the combustion state of the fuel gas is recovered to the set combustion state, the oxygen content e of the flue gas is recovered to the normal level along with the recovery of the oxygen content e of the flue gas. Because the oxygen content e of the flue gas in the normal combustion of the fuel gas is different along with the difference of the quantity of the combusted fuel gas, different upper limits e of the normal oxygen content are set according to different actual heat output quantities WmaxAnd lower limit of normal oxygen content eminThe gas combustion state in the gas water heater can be adjusted to the set combustion state with higher combustion efficiency under different working states of the water heater, namely under the condition of different smoke supply quantities.
In some embodiments of the method of the present invention, the control system of the gas water heater is further provided with an upper limit e of the safe oxygen content of the exhausted flue gasmax1And a lower safe oxygen content limit emin1. When the oxygen content e of the flue gas is larger than the upper limit e of the safe oxygen contentmax1When the gas burning device is used, the phenomenon that flame separation occurs during gas burning due to excessive air supply in the water heater, namely, excessive air input through the fan is caused, so that insufficient gas burning is caused, gas is wasted, and a large amount of CO is generated. And the phenomenon of excessive air supply can not be recovered by self-adjustment of the system, at the moment, the control system of the gas water heater sends alarm information, such as fault prompt that the oxygen content in the smoke is too high is displayed through a display screen, alarm sound is sent, and the gas supply of the gas water heater is forcibly stopped, so as to prevent safetyAnd (4) occurrence of all accidents. When the oxygen content e of the flue gas is less than the lower limit e of the safe oxygen contentmin1It is said that the air supply in the water heater is seriously insufficient, that is, the air quantity input by the fan is seriously insufficient, and the air supply shortage can not be recovered by self-adjustment of the system. At the moment, the phenomenon of backfire is easy to occur during the combustion of the gas, the burner is burnt out, the control system of the gas water heater sends alarm information, if the fault prompt that the oxygen content in the flue gas is too low is displayed through the display screen, the alarm sound is sent, and the gas supply of the gas water heater is forcibly stopped, so that the damage of the gas water heater and the occurrence of safety accidents are prevented.
As a specific embodiment of the method of the invention, the upper limit e of the normal oxygen content of a gas water heater at different actual heat output quantities W ismaxAnd lower limit of normal oxygen content eminThe control system of the gas water heater carries out self-learning on the detected value of the actual oxygen content e of the flue gas to obtain the oxygen content e of the flue gas by carrying out a certain time and forcibly simulating the work under different working conditions before the gas water heater leaves a factory. Namely, the maximum value of the flue gas oxygen content e actually measured under different actual heat output quantities W and different allowed working conditions in the pre-factory learning process of the gas water heater is taken as the upper limit e of the normal oxygen content when the actual heat output quantity W is equal tomax(ii) a The minimum value of the actually measured oxygen content e of the flue gas is taken as the upper limit e of the normal oxygen content when the actual heat output quantity W ismax. Thus, the upper limit e of the normal oxygen content corresponding to different actual heat output W, which meets the actual conditions of different gas water heaters, can be conveniently obtainedmaxValue of (d) and lower limit of normal oxygen content eminThe value of (c).
In some embodiments of the method of the present invention, the actual heat exchange efficiency of the gas water heater is determined by the control system from the flue gas temperature Te at different actual heat output W. The flue gas temperature Te of the gas water heater is not only related to the amount of heat absorbed by water flow, but also related to the amount of heat generated by gas combustion. And in the case of not considering the heat dissipation of the water heater tank, the heat generated by the combustion of the gas is equal to the heat absorbed by the water flow (i.e. the actual heat output W of the burner) and the heat discharged by the flue gas (which can be reflected by the flue gas temperature Te). And gas heater's actual heat exchange efficiency is actual heat output quantity W ÷ the heat that the gas combustion produced, consequently, combines together flue gas temperature Te and actual heat output quantity W, can more accurately judge gas heater actual heat exchange efficiency's height.
In some embodiments of the method of the invention, the control system of the gas water heater is provided with upper limits Te of normal flue gas temperature corresponding to different actual heating outputs Wmax. When the detected flue gas temperature Te is larger than the upper limit Te of the normal flue gas temperaturemaxIn the process, the scale formation degree of the heat exchange component obviously influences the heat exchange of the heat exchange component, the actual heat exchange efficiency of the gas water heater is obviously reduced, and the scale removal operation is required. At the moment, the control system of the gas water heater gives out scale formation alarm information, if the temperature of the flue gas is displayed to be higher through a display screen, scale removal treatment is required, and an alarm prompt sound can be given out to prompt a user to carry out scale removal operation. For example, acidic water is introduced to dissolve and drop the scale and acid through chemical reaction, so as to remove the scale and recover the heat conductivity of the heat exchange component.
As a specific embodiment of the method of the invention, the control system of the gas water heater is also provided with upper safe smoke temperature limits Te corresponding to different actual heat output quantities Wmax1. When the detected flue gas temperature Te is more than the upper limit Te of the safe flue gas temperaturemax1When the gas is normally combusted, the heat exchange effect of the heat exchange component is extremely poor. The incrustation scale on the inner wall of the heat exchange tube of the heat exchanger in the gas water heater can be judged to be serious, so that the heat generated by gas combustion is difficult to be transferred into the water flow in the heat exchange tube through the heat exchange tube. Heat accumulates on the heat exchange tubes, causing the temperature of the heat exchange tubes to rise significantly, burning the heat exchange tubes out easily, resulting in water leakage. At the moment, the control system gives alarm information, for example, the fault of overhigh smoke temperature is displayed through the display screen, the serious scale formation is prompted, and an alarm prompt sound can be given. Meanwhile, the control system forcibly stops the gas supply of the gas water heater, stops the work of the gas water heater and prevents the damage of the gas water heater.
As a specific embodiment of the method of the present invention, the upper limit Te of the normal flue gas temperature of a gas water heater at different actual heat output WmaxThe self-learning method can be obtained by carrying out a certain time and forcibly simulating the work under different working conditions before the gas water heater leaves a factory and carrying out the self-learning on the detected value of the smoke temperature Te by a control system of the gas water heater. Namely, the maximum value of the flue gas temperature Te actually measured under different actual heat output quantities W and different allowable working conditions in the process of learning before leaving the factory of the gas water heater is taken as the upper limit Te of the normal flue gas temperature when the actual heat output quantities W are differentmax. Therefore, the upper limit Te of the normal smoke temperature corresponding to different actual heat output quantities W and meeting the actual conditions of different gas water heaters can be conveniently obtainedmaxThe value of (c).
As shown in fig. 2, an embodiment of the method for detecting scale formation on a heat exchange component of a gas water heater of the present invention comprises the following steps:
1) the actual heating output W of the gas water heater is detected. The actual heat output quantity W of the water heater reflects the amount of heat energy actually output by the gas water heater during operation, and can be generally reflected by the quantity of gas combusted by the gas water heater and the temperature and flow conditions of output hot water, and also reflects the operating state of the gas water heater. The gas heater's flue gas exhaust condition is relevant with its operating condition, through the actual heating output W that detects gas heater, can distinguish the flue gas exhaust condition under the different operating condition, prevents because of the influence of operating condition difference to the testing result.
2) And detecting the oxygen content e of the flue gas discharged by the gas water heater. The oxygen content e of the flue gas refers to the residual oxygen content in the flue gas discharged after the combustion of the gas in the gas water heater, and is generally determined by the air supply amount during the combustion of the gas in the gas water heater, and the sufficient degree of the combustion of the gas is also reflected. Through the flue gas oxygen content e that detects in the exhaust flue gas, can learn the gas combustion state of gas heater during operation to make the judgement to heat transfer component heat exchange efficiency go on under the gas normal combustion state of settlement, prevent that the combustion state of gas from influencing the heat transfer effect of gas heater heat transfer component, thereby the influence is to the judgement of heat transfer efficiency. Generally, the oxygen content e of the flue gas can be detected by arranging an oxygen sensor at the smoke outlet of the gas water heater.
3) And adjusting the combustion state of the gas according to the oxygen content e of the flue gas under the current actual heat output quantity W, so that the combustion state of the gas is in a set normal combustion state. Because the combustion state of the fuel gas determines the oxygen content e of the discharged flue gas, the combustion state of the fuel gas can be known according to the oxygen content e of the flue gas. Therefore, the combustion state of the fuel gas can be adjusted to the set combustion state in a mode of adjusting the oxygen content e of the flue gas to the set level. When the gas water heater works under different actual heat output quantities, the oxygen content e of the flue gas in the exhausted flue gas is different under the normal combustion state of the gas, so the set level of the oxygen content e of the flue gas is different according to the difference of the actual heat output quantities W. Specifically, the combustion state of the gas may be adjusted by adjusting the supply amount of the gas, the supply amount of air for combustion supporting gas combustion, or the air flow rate of the gas supply, or the like. However, when the gas is operated, a user has specific requirements on the flow rate and the temperature of hot water output by the water heater, and therefore, the adjustment of the flue gas state needs to be comprehensively adjusted according to the requirements of the user. If the air flow speed is increased, the proportion of the fuel gas in the air flow needs to be reduced in order not to increase the water temperature.
4) And judging the actual heat exchange efficiency of the gas water heater according to the actual heat output W in the set combustion state, and judging the scale formation state of the heat exchange component according to the actual heat output W. The actual heat output quantity W reflects the quantity of heat absorbed by the water flow through the heat exchange of the heat exchange component, and the actual heat output quantity W is increased, so that the water flow absorbs more heat through the heat exchange component, and the actual heat exchange efficiency of the gas water heater is higher; on the contrary, the actual heat output quantity W is reduced, which indicates that the heat absorbed by the water flow passing through the heat exchange component is reduced, and the actual heat exchange efficiency of the gas water heater is reduced. Therefore, the actual heat output quantity W can reflect the actual heat exchange efficiency of the heat exchange part of the gas water heater. The actual heat exchange efficiency is determined by the heat conduction performance of the heat exchange component, the water flow and the water temperature, and the water flow and the water temperature are closely related to the actual heat output W, so that the heat conduction performance of the heat exchange component can be judged according to the actual heat output W in the set combustion state. And the scale formation degree of the heat exchange component is reflected by the change of the heat conduction performance of the heat exchange component in use, so that the scale formation state of the heat exchange component can be judged by setting the actual heat output W in a combustion state.
In some embodiments of the method of the present invention, the actual heating output W of the gas water heater may be obtained from the water flow Q, the inlet water temperature T0 and the outlet water temperature Tt of the gas water heater. Specifically, a water flow sensor may be provided in the water inlet path of the gas water heater to detect the water flow rate Q, a temperature sensor may be provided to detect the water inlet temperature T0, and a temperature sensor may be provided in the water outlet path of the gas water heater to detect the water temperature Tt. The actual heating output W is calculated by the formula W ═ Q × (Tt-T0). The calculation of the actual heating output W may be performed by a controller provided in the gas water heater.
In step 3), the combustion state of the gas may be adjusted by adjusting the air supply amount of the gas water heater or by adjusting the ratio of air mixed into the gas, depending on the type of the gas water heater. In particular, the speed n of the fan supplying the gas water heater with air can be adjusted, so as to adjust the amount of air supplied to the combustion chamber of the gas water heater, or to the premixer. By adjusting the amount of air supplied, the amount of oxygen in the burner can be adjusted, thereby adjusting the combustion state of the gas. The combustion state of the gas can be reflected through the oxygen content e of the flue gas, so that the combustion state of the gas can be adjusted in a mode of setting the level in the adjustment of the oxygen content e of the flue gas exhausted from the flue gas, and the combustion state of the gas in the gas water heater is always in the set combustion state.
In some embodiments of the method of the invention, the control system of the gas water heater is provided with upper limits e of the normal oxygen content of the exhaust fumes corresponding to different actual heat output quantities WmaxAnd lower limit of normal oxygen content emin. When the detected oxygen content e of the flue gas is at the upper limit e of the normal oxygen contentmaxAnd normally contains oxygenLower limit of quantity eminIn the range between, i.e. the oxygen content e of the flue gas is at the set value [ emin，emax]When the level is horizontal, the combustion state of the gas is in a normal set combustion state; when the oxygen content e of the flue gas is more than emaxWhen the combustion of the fuel gas is carried out, the oxygen supply is excessive, at the moment, the air supply can be reduced by reducing the rotating speed of the fan, the air supply quantity in the combustion chamber is reduced, or the proportion of premixed air in the fuel gas is reduced, so that the combustion state of the fuel gas is recovered to a set combustion state, and the oxygen content e of the flue gas is also recovered to a set level; when the oxygen content e of the flue gas is less than eminWhen the combustion state of the fuel gas is recovered to the set combustion state, the oxygen content e of the flue gas is recovered to the set level. Because the oxygen content e of the flue gas in the normal combustion of the fuel gas is different along with the difference of the quantity of the combusted fuel gas, different upper limits e of the normal oxygen content are set according to different actual heat output quantities WmaxAnd lower limit of normal oxygen content eminAnd the gas in the gas water heater can be adjusted to a normal set combustion state under different working states of the water heater.
In some embodiments of the method of the present invention, the control system of the gas water heater is further provided with an upper limit e of the safe oxygen content of the exhausted flue gasmax1And a lower safe oxygen content limit emin1. When the oxygen content e of the flue gas is larger than the upper limit e of the safe oxygen contentmax1When the gas burning device is used, the phenomenon that flame separation occurs during gas burning due to excessive air supply in the water heater, namely, excessive air input through the fan is caused, so that insufficient gas burning is caused, gas is wasted, and a large amount of CO is generated. And the phenomenon of excessive air supply can not be recovered through self-adjustment of the system, at the moment, the control system of the gas water heater sends alarm information, such as fault prompt that the oxygen content in the smoke is too high is displayed through a display screen, alarm sound is sent, and the gas supply of the gas water heater is forcibly stopped, so that safety accidents are prevented. When in useThe oxygen content e of the flue gas is less than the lower limit e of the safe oxygen contentmin1It is indicated that the air supply in the water heater is too small, that is, the amount of air input by the fan is too small, and the air supply is too small to be recovered by self-adjustment of the system. At the moment, the phenomenon of backfire is easy to occur during the combustion of the gas, the burner is burnt out, the control system of the gas water heater sends alarm information, if the fault prompt that the oxygen content in the flue gas is too low is displayed through the display screen, the alarm sound is sent, and the gas supply of the gas water heater is forcibly stopped, so that the damage of the gas water heater and the occurrence of safety accidents are prevented.
As a specific embodiment of the method of the invention, the upper limit e of the normal oxygen content of a gas water heater at different actual heat output quantities W ismaxAnd lower limit of normal oxygen content eminThe detected actual oxygen content e of the flue gas is obtained by self-learning the detected value of the actual oxygen content e of the flue gas by a control system of the gas water heater after the gas water heater is used for a certain time and under different simulated working conditions before leaving a factory. Namely, the maximum value of the flue gas oxygen content e actually measured under different actual heat output quantities W and different allowed working conditions in the pre-factory learning process of the gas water heater is taken as the upper limit e of the normal oxygen content when the actual heat output quantity W is equal tomax(ii) a The minimum value of the actually measured oxygen content e of the flue gas is taken as the upper limit e of the normal oxygen content when the actual heat output quantity W ismax. Thus, the upper limit e of the normal oxygen content corresponding to different actual heat output W, which meets the actual conditions of different gas water heaters, can be conveniently obtainedmaxValue of (d) and lower limit of normal oxygen content eminThe value of (c).
In some embodiments of the method of the present invention, the actual heat exchange efficiency of the gas water heater is determined by the control system based on the actual heat output W and the heat input parameter. The heat input parameter is a parameter related to the heat input of the gas water heater, namely, the amount of heat generated during combustion of the gas, and different heat input parameter values correspond to different heat input amounts. The existing gas water heater also adjusts the heat input quantity by adjusting the heat input parameter through the control system, the heat input parameter of the gas water heater can be obtained by acquiring the heat input parameter value currently executed in the control system through a program, and the heat input parameter of the gas water heater can also be detected by setting a responding sensor. For different gas water heater types, different types of heat input parameters can be used, generally, for a fully premixed gas water heater, the fan speed n can be used as the heat input parameter; for a common gas water heater, a fan rotating speed gas secondary pressure sequence (n, p) consisting of different fan rotating speeds n and gas secondary pressures p can be used as a heat input parameter. The actual heat exchange efficiency of the gas water heater can be accurately judged by reflecting the heat input parameter of the heat input quantity and the actual heat output quantity W, so that the scaling condition of the heat exchange part of the gas water heater can be accurately judged.
In some embodiments of the method of the present invention, a lower limit Wmin of normal actual heat output corresponding to different heat input parameters is set in the control system of the gas water heater. When the actual heat output W of the gas water heater is smaller than the lower limit Wmin of the normal actual heat output, the scale formation degree of the heat exchange component obviously influences the heat exchange of the heat exchange component, the actual heat exchange efficiency of the gas water heater obviously decreases, and scale removal operation is required. At the moment, the control system of the gas water heater gives out scale formation alarm information, if the actual heat output quantity is low through the display screen, scale removal treatment is needed, and alarm prompt sound can be given out to prompt a user to carry out scale removal operation. For example, acidic water is introduced to dissolve and drop the scale and acid through chemical reaction, so as to remove the scale and recover the heat conductivity of the heat exchange component.
As an embodiment of the method of the present invention, a safe actual lower heat output limit Wmin1 corresponding to different heat input parameters is also set in the control system of the gas water heater. When the actual heat output W of the gas water heater is smaller than the safe actual heat output lower limit Wmin1, the heat exchange effect of the heat exchange component is extremely poor when the gas is normally combusted. The incrustation scale on the inner wall of the heat exchange tube of the heat exchanger in the gas water heater can be judged to be serious, so that the heat generated by gas combustion is difficult to be transferred into the water flow in the heat exchange tube through the heat exchange tube. Heat accumulates on the heat exchange tubes, causing the temperature of the heat exchange tubes to rise significantly, burning the heat exchange tubes out easily, resulting in water leakage. At the moment, the control system gives alarm information, for example, the display screen displays that the fault that the actual heat output is too low occurs, the serious scale deposition can be prompted, and an alarm prompt sound can be given. Meanwhile, the control system forcibly stops the gas supply of the gas water heater, stops the work of the gas water heater and prevents the damage of the gas water heater.
As a specific implementation manner of the method of the present invention, the lower limit Wmin of the normal actual heat output of the gas water heater corresponding to different heat input parameters may be obtained by performing a certain time before the gas water heater leaves the factory, forcibly simulating the operation under different working conditions, and performing self-learning on the actual heat output W corresponding to different heat input parameters by the control system of the gas water heater. Namely, the gas water heater is forcibly controlled to work under various acceptable working conditions, the actual heat output W of the gas water heater under different heat input parameters is recorded, and the minimum value of the actual heat output W under various heat input parameters is taken as the lower limit Wmin of the normal actual heat output. Therefore, various values corresponding to different heat input parameters and meeting the normal actual heat output lower limit Wmin of different gas water heaters in actual conditions can be conveniently obtained.
One embodiment of the gas water heater of the present invention, as shown in fig. 3 and 4, comprises a water inlet 11, a water proportional valve 12, a heat exchanger 13, a water outlet 14, an air inlet 21, a gas proportional valve 22, an air inlet 23, a fan 24, a premixer 25, a burner 26, a smoke outlet 27 and a heat exchange component scale formation detection system. On the one hand, cold water flows into the gas water heater through the water inlet 11, and enters the heat exchanger 13 after the flow of the water is regulated by the water proportional valve 12. The heat exchanger 13 comprises a combustion chamber 131, a heat exchange tube 132, a heat exchange fin 133 and a smoke baffle 134, wherein the heat exchange fin 133 is installed on the heat exchange tube 132, and the heat exchange tube 132 and the heat exchange fin 133 are installed in the combustion chamber 131 so as to better form heat exchange with high-temperature smoke in the combustion chamber 131. A smoke barrier 134 is installed at the outlet of the combustion chamber 131 to regulate the velocity of the smoke flowing out of the combustion chamber 131. The cold water passes through the heat exchange pipe 132, exchanges heat with the high-temperature flue gas in the combustion chamber 131, absorbs heat to form hot water, and is discharged through the water outlet 14 for users to use. On the other hand, the gas enters the gas water heater through the gas inlet 21, the gas enters the premixer 25 after the flow of the gas is adjusted by the gas proportional valve 22, meanwhile, the air enters the premixer 25 through the air inlet 23 under the action of the fan 24 and is mixed with the gas in the premixer 25, and the mixed gas passes through the burner 26, is ignited by the burner 26, and is combusted in the burner 131. The combustion flue gas generated by the combustion exchanges heat with the water flow in the heat exchange pipe 132, and a large amount of heat is transferred to the water flow and then discharged through the smoke outlet 27 under the action of the fan 24. The scale formation detection system of the heat exchange part comprises a water flow sensor 31 and an inlet water temperature sensor 32 which are arranged in a water path near the water proportional valve 12, an outlet water temperature sensor 33 which is arranged on an outlet water path of the heat exchanger 13, a flue gas temperature sensor 34 and a flue gas oxygen content sensor 35 which are arranged in a flue gas discharge channel near the smoke outlet 27, and a controller 36, wherein a control program which can realize the scale formation detection method of the heat exchange part of the gas water heater provided by the invention is stored in the controller 36. The controller 36 may be provided separately or may be common to other control systems in the gas water heater. The controller 36 can receive the information detected by the water flow sensor 31, the inlet water temperature sensor 32, the outlet water temperature sensor 33, the flue gas temperature sensor 34 and the flue gas oxygen content sensor 35, and can also obtain the heat input parameters of the gas water heater from the normal operation control program of the gas water heater or through the sensors. And can send control information to control the work of the water proportional valve 12, the gas proportional valve 22 and the fan 24, so as to adjust the combustion state of the gas, send alarm information and forcibly stop the gas supply of the gas water heater according to the detection result, ensure the combustion effect of the gas, the heat exchange effect of the heat exchanger 13 and the safety performance of the gas water heater, and prolong the service life of the water heater.
In the description of the present invention, reference to the description of "one embodiment," "some embodiments," "a specific implementation," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In the present disclosure, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, simple modifications may be made to the technical solution of the invention, including combinations of the individual specific technical features in any suitable manner. Such simple modifications and combinations should be considered within the scope of the present disclosure as well.

Claims (19)

1. A method for detecting scale formation of a heat exchange part of a gas water heater is characterized by comprising the following steps:
1) detecting the actual heat output quantity (W) of the gas water heater;
2) detecting the oxygen content (e) of the flue gas discharged by the gas water heater;
3) adjusting the combustion state of the fuel gas to a set combustion state according to the oxygen content (e) of the flue gas under the actual heat output quantity (W);
4) detecting the temperature (Te) of the flue gas discharged by the gas water heater under the set combustion state;
5) and judging the actual heat exchange efficiency of the gas water heater according to the flue gas temperature (Te) and judging the scale formation state of the heat exchange component according to the actual heat exchange efficiency.
2. The method according to claim 1, characterized in that in step 1), the actual heating output (W) is obtained by detecting the water flow (Q), the inlet water temperature (T0) and the outlet water temperature (Tt) of a gas water heater; in step 3), the combustion state of the gas is adjusted to the set combustion state by adjusting the air supply amount of the gas water heater or adjusting the ratio of air mixed in the gas.
3. The method of claim 2, whichCharacterized in that in step 3) the upper limit (e) of the normal oxygen content of the exhausted fumes is set, corresponding to different said actual heat output (W)max) And lower limit of normal oxygen content (e)min) When the oxygen content (e) of the flue gas is larger than the upper limit of the normal oxygen content (e)max) When the gas water heater is used, the air supply quantity of the gas water heater is reduced, or the proportion of air mixed in gas is reduced; when the oxygen content (e) of the flue gas is less than the lower limit (e) of the normal oxygen contentmin) In this case, the air supply amount of the gas water heater is increased, or the ratio of air mixed in the gas is increased.
4. A method according to claim 3, characterized in that there is also provided an upper limit (e) for the safe oxygen content of the exhaust fumesmax1) And a lower safe oxygen content limit (e)min1) When the oxygen content (e) of the flue gas is larger than the upper limit of the safe oxygen content (e)max1) Or less than said safe lower oxygen content limit (e)min1) And sending alarm information and stopping the gas supply of the gas water heater.
5. Method according to claim 3 or 4, characterized in that said upper normal oxygen content limit (e) corresponds to different said actual heat output (W)max) And lower limit of normal oxygen content (e)min) The control system of the gas water heater is obtained in a self-learning mode before the gas water heater leaves a factory.
6. Method according to claim 1, characterized in that in step 5) the actual heat exchange efficiency is judged from the actual heat output (W) and flue gas temperature (Te).
7. Method according to claim 6, characterized in that there is provided an upper limit (Te) of the normal flue gas temperature corresponding to different said actual heat output (W)max) When the flue gas temperature (Te) is larger than the upper limit of the normal flue gas temperature (Te)max) And judging the scale formation of the heat exchange component and giving scale formation alarm information.
8. Method according to claim 7, characterized in that there is also provided an upper safety flue gas temperature limit (Te)max1) When the flue gas temperature (Te) is greater than the upper limit of the safe flue gas temperature (Te)max1) And judging that the scale formation of the heat exchange component is serious, giving out serious scale formation alarm information and stopping the gas supply of the gas water heater.
9. Method according to claim 7 or 8, characterized in that said upper limit of normal flue gas temperature (Te) corresponding to different said actual heating output (W)max) And the control system of the gas water heater is obtained in a self-learning mode before delivery.
10. A method for detecting scale formation of a heat exchange part of a gas water heater is characterized by comprising the following steps:
1) detecting the actual heat output quantity (W) of the gas water heater;
2) detecting the oxygen content (e) of the flue gas discharged by the gas water heater;
3) adjusting the combustion state of the fuel gas to a set combustion state according to the oxygen content (e) of the flue gas under the actual heat output quantity (W);
4) and judging the actual heat exchange efficiency of the gas water heater according to the actual heat output (W) in the set combustion state, and judging the scale formation state of the heat exchange component according to the actual heat output (W).
11. Method according to claim 10, characterized in that in step 1) said actual heating output (W) is obtained from the water flow (Q), the inlet water temperature (T0) and the outlet water temperature (Tt) of a gas water heater; in step 3), the combustion state of the gas is adjusted to the set combustion state by adjusting the air supply amount of the gas water heater or adjusting the ratio of air mixed in the gas.
12. Method according to claim 11, characterized in that there are provided upper limits of the normal oxygen content of the exhaust fumes corresponding to different said actual heat output (W)(emax) And lower limit of normal oxygen content (e)min) When the oxygen content (e) of the flue gas is larger than the upper limit of the normal oxygen content (e)max) When the gas water heater is used, the air supply quantity of the gas water heater is reduced, or the proportion of air mixed in gas is reduced; when the oxygen content (e) of the flue gas is less than the lower limit (e) of the normal oxygen contentmin) In this case, the air supply amount of the gas water heater is increased, or the ratio of air mixed in the gas is increased.
13. Method according to claim 12, characterized in that there is also provided an upper limit (e) for the safe oxygen content of the exhaust fumesmax1) And a lower safe oxygen content limit (e)min1) When the oxygen content (e) of the flue gas is larger than the upper limit of the safe oxygen content (e)max1) Or less than said safe lower oxygen content limit (e)min1) And sending alarm information and stopping the gas supply of the gas water heater.
14. Method according to claim 12 or 13, characterized in that said upper normal oxygen content limit (e) corresponds to different said actual heat output (W)max) And lower limit of normal oxygen content (e)min) The control system of the gas water heater is obtained in a self-learning mode before the gas water heater leaves a factory.
15. Method according to claim 10, characterized in that in step 5) the actual heat exchange efficiency is judged from the actual heat output (W) and heat input parameters; the heat input parameter is the rotating speed (n) of the fan or a secondary pressure sequence (n, p) of the gas at the rotating speed of the fan.
16. The method according to claim 15, wherein a lower normal actual heat output limit (Wmin) is set corresponding to different heat input parameters, and when the actual heat output (W) is less than the lower normal actual heat output limit (Wmin), scaling of the heat exchange part is judged, and scaling alarm information is given.
17. The method according to claim 16, wherein there is further provided a safe actual heat output lower limit (Wmin1), and when the actual heat output (W) is less than the safe actual heat output lower limit (Wmin1), it is judged that the heat exchange part is scaling seriously, a scale serious alarm is given, and the gas supply of the gas water heater is stopped.
18. Method according to claim 16 or 17, characterized in that said lower normal actual heat output limit (Wmin) corresponding to different said heat input parameters is obtained by the control system of the gas water heater by means of self-learning before leaving the factory.
19. A gas water heater comprising a heat exchange part scale formation detection system for detecting scale using the gas water heater heat exchange part scale formation detection method of any one of claims 1 to 18.
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