沼气集中供气工程太阳能增温技术研究

发布时间：2018-06-04 01:07

本文选题：沼气工程 + 太阳能　；参考：《浙江大学》2017年硕士论文

【摘要】：户用沼气正在向整村沼气集中供气转变,大中型沼气池具有广阔的发展前景,研究开发太阳能沼气池供热系统具有十分重要的意义。本文针对大中型沼气池冬季发酵温度低、控制方式不合理等问题,对太阳能沼气池供热系统进行深入研究。对浙江省诸暨市太阳能加热沼气工程和浙江省开化县太阳能-空气源热泵加热沼气工程的池内外热环境进行现场连续检测,检测参数包括室外环境参数(环境温度、太阳总辐射强度、风速风向)、沼气池温度、水箱温度和热流量。并利用测试数据分析两个实验沼气池的加热系统性能,找出系统薄弱环节提出改进意见。研究结果表明,浙江诸暨地区的太阳能加热沼气工程,在2015年12月8日至2016年3月31日期间,总热负荷中占比最大的是池体散热,其中顶部散热量占总热负荷的29.39%～29.74%,底部散热量占18.09%～18.39%,侧壁散热量占38.41%～39.03%。12月8日～1月27日由于太阳能辐射强度小、循环温差设定值较高导致无法达到当前设定循环温差,所以沼气池在该期间没有得到热量。当前投料量远低于理论投料量,从22℃开始即使沼液温度增加,产气量也不会增加。浙江开化地区的太阳能-空气源热泵加热沼气工程,在2015年12月9日至2016年3月31日测试期间,总的热损失中沼气池最主要的能量散失途径是池体散热量,顶部散热量占36.33%～41.98%,底部散热量占19.70%～27.55%,侧壁散热量占14.94%～15.80%。沼气池的发酵温度上限值是23℃,超过这个上限值后即使发酵温度增加产气量也不会增加。利用能量守恒原理建立太阳能沼气池供热系统数学模型,并用模拟值和实测值之间的平均误差和平均相对误差验证模型的准确性。结果表明,在典型的晴天、多云和阴天,开化县沼气池和诸暨沼气池中的料液温度的检测值和模拟值的最大平均误差分别是0.159℃和0.285℃,其最大相对误差分别为0.73%和1.47%,模型准确度良好。根据诸暨太阳能沼气池供热系统模型,利用与诸暨地区相近的杭州典型年数据进行模拟,改变太阳能集热器与储热水箱、储热水箱与沼气池之间的循环温差。结果发现:在12月～3月,太阳能与储热水箱和储热水箱与沼气池沼液的循环温差为(15℃,10℃、(15℃,5℃、(10℃,10℃、(10℃,5℃ 和(5℃,5℃时的平均温度比当前的循环温差(15℃,15℃)下分别高2.49℃、3.48℃、3.57℃、4.64℃和5.41℃。在当前投料量下循环温差为(5℃,5℃)的时候,12月份～3月份发酵温度都高于22℃,日产气量保持68m3左右。所以循环温差如果继续减小,发酵温度会增加,但是在投料量不变的情况下,产气量不变,因此建议循环温差设置为(5℃,5℃)。根据建立的开化太阳能沼气池供热系统模型,利用与开化地区相近的衢州典型年数据模拟分析发酵温度23℃时的系统运行情况。得出以下结论:(1)在系统总耗电量中热泵机组耗电量占据的份额最大,达到60%以上;(2)低温季节的系统总耗电量占全年系统总耗电量的80.29%;(3)集热器面积在50m2～100m2时,联合加热系统的经济性优于单独的空气源热泵加热系统。如果集热器单价在700元/m2内,投资效益净现值随太阳能集热器面积的增加而增加。在太阳能集热器单价为800元/m2时,投资效益净现值在80 m2时达到最大值,然后开始减小。最后,设计计算一个杭州地区利用太阳能和空气源热泵联合加热的500 m3标准钢筋混凝土沼气池,然后建立相应的太阳能沼气池供热系统数学模型,模拟分析了杭州地区典型年利用太阳能和空气源热泵联合加热的500m3标准钢筋混凝土沼气池的两种情况:(1)给定加热系统改变发酵温度设定值;(2)给定发酵温度和空气源热泵功率改变太阳能面积。得出以下结论:1.加热系统中太阳能集热器面积为184m2,空气源热泵机组功率7.5kW时,在20℃～30℃发酵温度范围内,在沼气定价为1.2元/m3时,在低温季节和全年情况下,净利润都先增加后减小,并且都在29℃时达到最大值。所以如果以利润最大化为目标,建议全年发酵温度设定在29℃。将沼气换算为天然气价格时,售价为2.27元/m3,低温季节和全年的净利润在20℃～30℃内都随着发酵温度增加而增加,所以发酵温度设定值越高经济性越好。2.给定发酵温度25℃,对应的加热系统中加热系统中空气源热泵机组功率为7.5kW,太阳能集热器面积变化区间是30 m2～250 m2。太阳能集热器单价为500元/m2时,投资效益净现值为正值且随着集热器面积增加而增加。集热器单价为600、700和800元/m2时,投资效益净现值最大时对应的集热器面积分别是220 m2、210 m2 和 170 m2。
[Abstract]:The household biogas is changing to the whole village biogas, and the large and medium-sized biogas pool has a broad development prospect. It is of great significance to study and develop the heating system of the solar biogas pool. In this paper, the heating system of the solar biogas digester is deeply researched in view of the low fermentation temperature of the large and medium-sized biogas digesters in winter and the unreasonable control methods. The thermal environment of the solar heating biogas project in Zhuji, Zhejiang and the heat environment of the solar air source heat pump in Kaihua County, Zhejiang Province, was tested in a continuous field. The parameters included outdoor environmental parameters (ambient temperature, total solar radiation intensity, wind speed and wind direction), the temperature of the biogas pool, the temperature of the water tank and the heat flow. The test data analyses the performance of the heating system of two experimental biogas pools and finds out the weakness of the system. The results show that the maximum heat load in the total heat load in the Zhuji area of Zhejiang is the largest in the total heat load during the period from December 8, 2015 to March 31, 2016, and the amount of the top heat dissipation in the total heat load is the total heat load. From 29.39% to 29.74%, the heat dissipation at the bottom is 18.09% ~ 18.39%, the heat dissipation of the side wall is 38.41% ~ 39.03%.12 months 8 ~ January 27th, because the solar radiation intensity is small and the set value of the cycle temperature difference is high, which can not reach the current set cycle temperature difference, so the biogas pool has not got the heat during this period. The current dosage is far below the theoretical dosage, from 2. The amount of gas production will not increase even if the temperature of the biogas liquid is increased at 2 C. The solar air source heat pump in the Zhejiang Kaihua area is used to heat the biogas project. During the period from December 9, 2015 to March 31, 2016, the main energy dissipation way of the total heat loss in the total heat loss is the amount of heat dissipation in the pool, the heat dissipation at the top is 36.33% to 41.98%, and the bottom heat dissipation is in the bottom. The amount of 19.70% ~ 27.55% and the upper limit of the fermentation temperature of the side wall heat dissipation in 14.94% ~ 15.80%. methane pool is 23. After the upper limit is above the upper limit, the gas production will not increase even if the fermentation temperature increases. By using the principle of conservation of energy, the mathematical model of the heating system of the solar biogas pool is established, and the average error between the simulated and measured values is peaceful. The results show that the maximum average errors of the measured values and the simulated values of the liquid temperature in the typical sunny days, cloudy and cloudy days, and the maximum average errors of the measured and simulated values in the biogas pool and the Zhuji biogas pool in Kaihua County are 0.159 and 0.285, respectively, and the maximum relative errors are 0.73% and 1.47% respectively, and the accuracy of the model is good. According to Zhuji too The heat supply system model of the Yang energy digester is used to simulate the cycle temperature difference between the solar collector and the heat storage tank, the heat storage tank and the biogas pool in Zhuji, which is similar to the Hangzhou typical year data. The results show that the cycle temperature difference between the solar energy storage tank and the hot water storage tank and the biogas tank from December to March is (15, 10). At 15, 5, (10, 10, 10, 5, 5, 5), the average temperature was higher than the current cycle temperature difference (15, 15, 15), respectively, higher 2.49 degrees, 3.48, 3.57, 4.64, and DEG C. The temperature difference between December and March was higher than that of 68m3. If the cycle temperature difference continues to decrease, the fermentation temperature will increase, but the amount of gas production is constant when the feeding amount is constant. Therefore, it is suggested that the cycle temperature difference be set to (5 degrees C, 5 C). According to the established model of the heating system of the solar biogas digester, the fermentation temperature is simulated and analyzed by the typical year data of Quzhou, which is close to the Kaihua area. The following conclusions are drawn: (1) the share of the power consumption of the heat pump unit is the largest in the total energy consumption of the system, reaching more than 60%. (2) the total energy consumption of the system in the low temperature season accounts for 80.29% of the total energy consumption of the whole year system. (3) the economy of the combined heating system is superior to the separate air source heat pump when the collector area is 50m2 to 100m2. If the unit price of the collector is within 700 yuan /m2, the net present value of the investment benefit increases with the increase of the solar collector area. When the unit price of the solar collector is 800 yuan /m2, the net present value of the investment benefit reaches the maximum at 80 m2, and then begins to decrease. Finally, a solar and air source heat pump in Hangzhou area is designed and calculated. The 500 m3 standard reinforced concrete biogas digester was heated, and then the corresponding mathematical model of the solar biogas pool heating system was established. Two cases of the typical 500m3 standard reinforced concrete biogas pool, which was combined with solar energy and air source heat pump in Hangzhou area, were simulated and analyzed. (1) a given heating system changed the setting value of the fermentation temperature; (2 Given the given fermentation temperature and the power of the air source heat pump to change the area of solar energy, the following conclusions are drawn: 1. when the area of the solar collector is 184m2 and the power of the air source heat pump unit is 7.5kW, the value of the biogas price is 1.2 yuan /m3, and the net profit is increased first in the low temperature season and the whole year. Reduce, and reach the maximum at 29 degrees. So if the maximum profit is taken as the goal, it is suggested that the fermentation temperature of the year be set at 29. When the biogas is converted to natural gas price, the price is 2.27 yuan /m3, the low temperature season and the whole year net profit increase with the increase of the fermentation temperature at 20 to 30 degrees, so the higher the temperature of the fermentation is, the more the temperature is set. The high economy is better, the better the.2. temperature is 25 C, the air source heat pump unit in the heating system is 7.5kW in the heating system, the area of the solar collector area is 30 m2 to 250 m2. solar collector unit price of 500 yuan /m2, the net present value of the investment benefit is positive and increases with the increase of the collector area. For the 600700 and 800 yuan /m2, the area of the collector area corresponding to the maximum net present value of investment benefits is 220 m2210 m2 and 170 m2. respectively.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S216.4;S214

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