The wind of frequency conversion fan control method in gas hot water heating furnace

Release time: 2013 - 12 - 11
Views: 100
   The wind of frequency conversion fan control method in gas hot water heating furnace

Abstract:
In this paper, the hot water heating gas boiler for constant speed under the hood fan control mode and two fan drum wind frequency conversion fan control mode control mode were expounded and parsing, according to the characteristics of the product and the future development trend of low carbon economy, under the one blast focuses on frequency conversion fan control method in the analysis and explanation.
 
Key words:
Gas heating furnace hot water;Constant speed hood fan control mode;Combustion efficiency;Air volume;Energy waste;The drum wind frequency conversion fan control mode;The fan into the air;A small fire to maintain
 
0. Preface:
Along with the low carbon economy, energy conservation and emissions reduction policy escalated, environmental protection and energy saving environment gradually formed.Household hot water heating gas boiler combustion control technology upgrade is imperative.Need on the basis of the original energy efficiency (thermal efficiency) is higher, at the same time with fewer emissions, flue gas emissions more environmentally friendly.Each gas hot water heating furnace manufacturing enterprises are also trying to research and development, constantly improve and enhance the combustion performance of household hot water heating gas boiler.As far as I know, at present the hot water heating furnace burning gas that sells on the market, the vast majority are using constant speed hood fan control technology.To achieve higher thermal efficiency, lower flue gas emission temperature is the premise of fully complete combustion of fuel gas.Blast under frequency conversion fan control technology was born in this background, the author will focus on blast under frequency conversion fan control method was presented and analyzed.
 
Body:
1. Constant speed hood fan control technology
In European common household hot water heating gas boiler combustion control process, shaded pole fan is constant speed control, the fire burns or small fire burning fan speed is constant, this control method can cause small fire burning air volume is too big, row away heat, resulting in a decline in the efficiency of the furnace gas heating hot water;The second is when the flue exhaust poor blocked or against the wind, also will cause the loss of gas hot water heating furnace combustion efficiency, emissions, environmental pollution.When indoor temperature, under the state of thermal equilibrium, and only small fire burning to maintain at this point, constant speed cover a fan in this case will still be at maximum exhaust air volume, cause unnecessary waste of energy.Shaded pole fan in high temperature smoke, high temperature flue gas will accelerate hood fan motor aging, easy cause fan and fan noise attenuation performance.        
Constant speed cover a blower fan speed control mode and current relationship of proportional valve, specific curve as shown in the figure below:

 

 

2. Shaded pole fan speed control technology

Fan speed, flue exhaust fan, air volume and smooth degree (such as wind, jams, etc.).Wind is changes with changes in the environment, can't control, so when a fan air volume is not enough, must be tested for fan air volume change, make compensation control of air flow and fan air volume can be achieved with the optimal control of gas proportional valve volume ratio.Therefore, through the changes of the fan air volume, and the shaded pole fan speed regulation control, air volume compensation control, can improve the combustion efficiency of fuel gas furnace heating hot water pollution and reduce greenhouse gas emissions.

Currently on the market, has appeared on the suction hood fan speed regulation, and corresponding formula of gas proportional valve to do some adjustment, have made a certain progress to promote the efficiency of the.But on the suction hood pole machine there are still some weaknesses in the performance and requirement, because of the suction hood pole machine in collect smoke cover, the flue gas temperature is greater than 130 degrees above, high temperature flue gas of shaded pole motor and cover pole motor governor on impact, reduce its service life and reliability.So you need both in software and hardware control can do some special processing is suitable for mass production, from the current manufacturer to a short trial, popular reaction can increase the combustion efficiency, obtained the certain energy-saving effect.

3. The next blast frequency conversion fan control technology

On the market at present the ideal and the most mature wind speed regulation scheme is from Japan and South Korea under the type of frequency conversion fan drum wind technology control scheme, adopt the way of blast control wind speed, air volume and proportional valve of the gas output to achieve the best match, the automatic control of frequency conversion fan air volume of fan motor with proportional valve of the gas output automatically adjust fan ventilation air volume.To achieve automatic control of air volume. Because of the blast blower with the brushless dc frequency conversion motor, so the scheme of cost is higher than now in general use the gas heating water heater manufacturer of hood fan control scheme.Because of frequency conversion fan in be used actually is fixed in the bottom wall hanging furnace combustion chamber, the environment temperature is less than 60 degrees, the air inlets, also belong to the natural air temperature, environment temperature and inlet air temperature is not high, so the original device of frequency conversion fan motor speed regulation within the direct impact on the performance and life of not, can ensure that the frequency conversion fan, effective and safe working for a long time.Is more advantageous to gas heating furnace hot water stable quality of the machine.

Blast under frequency conversion fan fan rotation speed control mode and current relationship of proportional valve, the specific curve as shown in the figure below:

2013061309212263.png

 

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 In order to make everyone on the blast energy saving effect of frequency conversion fan control mode has a more profound understanding and awareness.The author very fan control technology for the same power with constant speed cover (model: L1PB18) and under blast fan control technology (model: L1GB18) each one gas hot water heating furnace to do the contrast test experiment.
Environmental conditions of inspection: 20 ℃ and 101.4 kPa.
Laboratory standards: GB25034-2010 "gas heating furnace, hot water
Laboratory conditions:
: a) laboratory temperature 20 ℃ + / - 5 ℃;
B) the water temperature: 20 ℃ plus or minus 2 ℃;
C) the laboratory temperature and water temperature difference should be less than or equal to 5 k
D) other conditions should comply with the requirements of GB/T16411.
Thermal equilibrium condition: test of thermal equilibrium state is refers to the flow of water and return water temperature stability within the plus or minus 2 k.
Power conditions: 220 v, 50 hz.
White gas parameters: China number: (MJ/M3) 50.73 combustion potential: 40.3 gas pressure rating: 2000 pa
The main test instruments and equipment:
Weather chromatograph, flue gas analyzer, wet gas flowmeter, the whole machine test bed
Apparatus according to the nameplate in the rated load condition, the labeling regulations, running after reaching heat balance, gas flow rate is measured with gas meter, gas meter pointer running more than a week, and the determination of time not less than 1 min, gas consumption will be measured according to the formula (1) heat input converted to benchmark condition.When using the wet type flowmeter measurement, using formula (2) to modify the gas density;Use dh instead of d.
 

3.png

Type:
Q - 20 ℃ and atmospheric pressure of 101.4 kPa, convert heat input values under dry state, the unit is kilowatts (kW);
Hi - 20 ℃ and 101.4 kPa numerical benchmark gas low calorific value, unit of megajoule per standard cubic meters (MJ/Nm3);
V - test the value of gas flow, the unit is cubic meters per hour (m3 / h);
Pg - test when the gas pressure inside the gas flowmeter numerical, units for the kPa (kPa);
Pa -- test, the value of the atmospheric pressure, the unit for the kPa (kPa);
Tg - test gas flowmeter, the value of gas temperature, when the unit is degrees Celsius (℃);
D - dry gas test, the value of relative density;
Dr Benchmark - gas, the value of relative density;
PS - in the saturated vapor pressure of tg values, the unit is kPa (kPa.)
Same experimental conditions, the thermal efficiency test load heating appliances run after reaching heat balance test, in 10 minutes for a cycle, according to the minimum rated heat input and the percentage of heat input to calculate burning time t1, calculate the consumption of gas in the t1 time volume V, and record the average water temperature of heating in 10 minutes of theta average theta. 2, 1 and heating water temperature heating water flow qV
According to the formula (3) (4) calculation

4.png

After thermal efficiency testing results compared to the following table (a) :
 
型号
 
额定热输入时采暖热效率(%)
部分负荷下采暖模式热效率(%)
额定负荷下热水模式热效率
(%)
 
备注
L1PB18
88.2
84.6
88.3
上吸风定速罩极风机控制
L1GB18
92.6
96.5
92.5
下鼓风变频风机控制
Special combustion adjustment according to the requirement to the limit of heat input, incomplete combustion, the flame combustion, the wind is burned by flue gas analyzer to analyze the flue exhaust gas test.The results in the following table (2)
Special combustion experimental results contrast table CO content (2) :
 
型号
 
极限热输入时CO含量(%)
不完全燃烧时CO含量(%)
离焰燃烧时CO含量(%)
有风燃烧时CO含量(%)
 
 
备注
L1PB18
0.033
0.151
0.007
0.007
上吸风定速罩极风机控制
L1GB18
0.003
0.019
0.001
0.002
下鼓风变频风机控制
The wind of frequency By experimental results contrast table (a), (2) it can be seen as the blast fan can control the frequency conversion air volume and the linkage of the best proportional valve of the gas output.Than using suction hood work mode of the fan control in thermal efficiency, has made great progress in such aspects as CO content, energy saving and environmental protection effect is obvious.Especially under partial load thermal efficiency than using suction hood work mode of the fan control increased by 11.9%.The effect is particularly significant.
 
 
Conclusion:
1. With the low carbon economy sustained and in-depth, environmental protection and energy saving environment, gas hot water heating furnace technology, it is imperative to upgrade under blast the use of frequency conversion fan control technology will shine brilliantly.
2. As the gas hot water heating furnace of a buyer's market has become increasingly rational, blast under significant energy saving effect of frequency conversion fan control technology, this technology in the near future will get more extensive use and promotion.
3. The suction hood work extremely on the fan control mode only by adjusting the current of proportional valve to adjust the volume, whether it is a minimum power, power and maximum combustion fan speed is constant, the heat loss is big, burning consumption.But under blast frequency conversion fan control mode on the basis of proportional valve to adjust current into the air.Fan air inflow by PID control, according to the change of heat load, the linkage of the fan speed change, reducing heat loss, the ratio of air and gas fully burning.So under blast fan control on combustion is better than the way of suction fan control mode of constant speed cover very burning more completely and fully.Exhaust smoke temperature is lower and higher thermal efficiency.
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