基于機(jī)械熱泵的海水淡化零排放研究
發(fā)布時(shí)間：2018-07-31 08:05
【摘要】：海水淡化是一種高能耗產(chǎn)業(yè),目前,市場(chǎng)上主流的海水淡化方法主要有反滲透海水淡化,多級(jí)閃蒸海水淡化,低溫多效海水淡化等。反滲透海水淡化對(duì)于海水的品質(zhì)有較高的要求,適應(yīng)性能比較弱,多級(jí)閃蒸海水淡化系統(tǒng)的能耗較高,低溫多效方法現(xiàn)在已經(jīng)日趨成熟,得到廣泛應(yīng)用。然而熱法海水淡化實(shí)現(xiàn)零排放時(shí)能耗大,傳統(tǒng)的膜法海水淡化方法無法實(shí)現(xiàn)零排放,而是將海水鹽濃度濃縮至6%后,直接排入大海。長(zhǎng)此以往,高鹽濃度的海水直接排入大海對(duì)周圍海域的生態(tài)環(huán)境會(huì)造成不良影響。隨著世界能源危機(jī)和環(huán)境危機(jī)問題的日益顯著,設(shè)計(jì)并開發(fā)新型低能耗清潔的海水淡化系統(tǒng)迫在眉睫。本文以機(jī)械熱泵技術(shù)為背景,設(shè)計(jì)出了海水淡化的零排放系統(tǒng),將鹽濃度為3%的海水濃縮至28.92%,結(jié)晶之后系統(tǒng)產(chǎn)物為淡水和鹽。通過對(duì)單級(jí)、兩級(jí)和三級(jí)系統(tǒng)的能耗比較,在此基礎(chǔ)上,針對(duì)一級(jí)系統(tǒng)進(jìn)行能量分析,主要做出口海水鹽濃度變化對(duì)系統(tǒng)火用損的影響,其中可以達(dá)到零排放效果的只有出口濃度為28.92%。分析結(jié)果表明,隨著出口濃度的不斷增加,系統(tǒng)的火用損呈緩慢上升趨勢(shì)。針對(duì)兩級(jí)海水淡化系統(tǒng)進(jìn)行火用分析,建立系統(tǒng)主要部件的火用模型。兩級(jí)海水淡化零排放系統(tǒng)具體分析了一級(jí)閃蒸出口的海水鹽濃度對(duì)整個(gè)系統(tǒng)火用損的影響,結(jié)果表明,系統(tǒng)火用損隨著一級(jí)閃蒸出口的海水濃度的升高,并不呈單一趨勢(shì)變化,而是先下降后升高。故以一級(jí)閃蒸出口的鹽濃度為自變量,擬合出系統(tǒng)火用損的函數(shù),并根據(jù)擬合結(jié)果可以得到系統(tǒng)火用損的曲線,通過對(duì)函數(shù)的求導(dǎo),可以得出最具節(jié)能效果的濃度分配,結(jié)果表明,一級(jí)閃蒸出口的海水鹽濃度在10%的時(shí)候,整個(gè)系統(tǒng)的火用損達(dá)到最小值。此外,通過本實(shí)驗(yàn)室既有的處理高濃度含鹽廢水的工程實(shí)踐結(jié)果,即采用同樣的方法對(duì)高濃度含鹽廢水的處理實(shí)驗(yàn)進(jìn)行分析,得到的結(jié)果與工程實(shí)踐結(jié)果進(jìn)行對(duì)比,可以證明此種分析方法具有較強(qiáng)的適用性和可靠性。最后,針對(duì)三級(jí)系統(tǒng),本文采用多變量?jī)?yōu)化分析的方法,針對(duì)系統(tǒng)中一級(jí)和二級(jí)的出口海水鹽濃度的變化,分析了系統(tǒng)總的能耗變化,介紹了多變量分析理論,并將其運(yùn)用到海水淡化系統(tǒng)分析中去。本文從經(jīng)濟(jì)和耗能角度對(duì)一級(jí)、二級(jí)和三級(jí)海水淡化系統(tǒng)進(jìn)行分析。
[Abstract]:Seawater desalination is a kind of high energy consumption industry. At present, the main desalination methods in the market include reverse osmosis desalination, multi-stage flash desalination, low-temperature multi-effect seawater desalination and so on. Reverse osmosis seawater desalination has higher requirements for seawater quality, weak adaptability, high energy consumption of multi-stage flash desalination system, and has become increasingly mature and widely used in low-temperature multi-effect desalination system. However, the traditional membrane desalination method can not achieve zero discharge when the thermal desalination achieves zero discharge. Instead, the concentration of seawater salt is concentrated to 6% and discharged directly into the sea. In the long run, sea water with high salt concentration will have adverse effects on the ecological environment of the surrounding sea. With the world energy crisis and environmental crisis increasingly prominent, it is urgent to design and develop a new low energy consumption and clean desalination system. Under the background of mechanical heat pump technology, a zero discharge system for desalination of seawater is designed. The salt concentration of 3% seawater is concentrated to 28.92%. After crystallization, the products of the system are fresh water and salt. By comparing the energy consumption of single-stage, two-stage and three-stage systems, on the basis of this, the energy analysis of the primary system is carried out, and the influence of salt concentration change at the outlet on the exergy loss of the system is mainly done. Only the export concentration of 28.92% can achieve zero emission effect. The results show that the exergy loss of the system increases slowly with the increasing of outlet concentration. The exergy analysis of two-stage seawater desalination system is carried out and the exergy model of the main components of the system is established. The effect of seawater salt concentration at the primary flash outlet on the exergy loss of the whole system is analyzed in detail in a two-stage desalination zero discharge system. The results show that the exergy loss of the system does not change with the increase of seawater concentration at the primary flash outlet. But first down and then up. Therefore, the function of exergy loss of the system is fitted with the salt concentration at the outlet of the first stage flash, and the curve of the exergy loss of the system can be obtained according to the fitting results. Through the derivation of the function, the concentration distribution with the most energy saving effect can be obtained. The results show that the exergy loss of the whole system reaches the minimum when the salt concentration at the outlet of the first stage flash is 10%. In addition, through the existing engineering practice results of the treatment of high concentration salt-containing wastewater in our laboratory, that is, using the same method to analyze the treatment experiment of the high-concentration salt-containing wastewater, the results obtained are compared with the engineering practice results. It can be proved that this analytical method has strong applicability and reliability. Finally, aiming at the three-level system, this paper uses the method of multivariable optimization analysis to analyze the total energy consumption change of the system, and introduces the theory of multivariable analysis, aiming at the change of salt concentration in the first and second level of the system. It is applied to the analysis of seawater desalination system. In this paper, the primary, secondary and tertiary desalination systems are analyzed from the point of view of economy and energy consumption.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P747
，
本文編號(hào)：2154953
[Abstract]:Seawater desalination is a kind of high energy consumption industry. At present, the main desalination methods in the market include reverse osmosis desalination, multi-stage flash desalination, low-temperature multi-effect seawater desalination and so on. Reverse osmosis seawater desalination has higher requirements for seawater quality, weak adaptability, high energy consumption of multi-stage flash desalination system, and has become increasingly mature and widely used in low-temperature multi-effect desalination system. However, the traditional membrane desalination method can not achieve zero discharge when the thermal desalination achieves zero discharge. Instead, the concentration of seawater salt is concentrated to 6% and discharged directly into the sea. In the long run, sea water with high salt concentration will have adverse effects on the ecological environment of the surrounding sea. With the world energy crisis and environmental crisis increasingly prominent, it is urgent to design and develop a new low energy consumption and clean desalination system. Under the background of mechanical heat pump technology, a zero discharge system for desalination of seawater is designed. The salt concentration of 3% seawater is concentrated to 28.92%. After crystallization, the products of the system are fresh water and salt. By comparing the energy consumption of single-stage, two-stage and three-stage systems, on the basis of this, the energy analysis of the primary system is carried out, and the influence of salt concentration change at the outlet on the exergy loss of the system is mainly done. Only the export concentration of 28.92% can achieve zero emission effect. The results show that the exergy loss of the system increases slowly with the increasing of outlet concentration. The exergy analysis of two-stage seawater desalination system is carried out and the exergy model of the main components of the system is established. The effect of seawater salt concentration at the primary flash outlet on the exergy loss of the whole system is analyzed in detail in a two-stage desalination zero discharge system. The results show that the exergy loss of the system does not change with the increase of seawater concentration at the primary flash outlet. But first down and then up. Therefore, the function of exergy loss of the system is fitted with the salt concentration at the outlet of the first stage flash, and the curve of the exergy loss of the system can be obtained according to the fitting results. Through the derivation of the function, the concentration distribution with the most energy saving effect can be obtained. The results show that the exergy loss of the whole system reaches the minimum when the salt concentration at the outlet of the first stage flash is 10%. In addition, through the existing engineering practice results of the treatment of high concentration salt-containing wastewater in our laboratory, that is, using the same method to analyze the treatment experiment of the high-concentration salt-containing wastewater, the results obtained are compared with the engineering practice results. It can be proved that this analytical method has strong applicability and reliability. Finally, aiming at the three-level system, this paper uses the method of multivariable optimization analysis to analyze the total energy consumption change of the system, and introduces the theory of multivariable analysis, aiming at the change of salt concentration in the first and second level of the system. It is applied to the analysis of seawater desalination system. In this paper, the primary, secondary and tertiary desalination systems are analyzed from the point of view of economy and energy consumption.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P747
，
本文編號(hào)：2154953
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