技术领域technical field
本实用新型属于太阳能热发电技术领域，尤其涉及一种具有不同放热模式的太阳能复叠朗肯循环发电系统。The utility model belongs to the technical field of solar thermal power generation, in particular to a solar cascade Rankine cycle power generation system with different heat release modes.
背景技术Background technique
螺杆膨胀机可以处理液态、气液两相态以及气态工质，而且与透平膨胀机相比，其具有良好的变工况性能。在太阳能热发电系统（Solar electricity generation system，SEGS）中，采用蒸汽螺杆膨胀机，构建水蒸汽-有机工质复叠朗肯循环系统（steam-organicRankinecycle，SORC）可以避免过热装置，在相对较低的温度和压力下系统也能够保证较高的效率。比如，当热源温度在250℃时，系统发电效率在15%左右。此外，当采用水作为蓄热工质时，系统还可以采用直膨式技术（direct steam generation，DSG），使得太阳能热发电系统具有灵活的操作性以及优良的热力学性能。但是，基于水蓄热的直膨式太阳能复叠朗肯循环发电系统（DSG-SORC），仍然面临一些挑战：The screw expander can handle liquid, gas-liquid two-phase and gaseous working fluid, and compared with the turbo expander, it has good performance in variable working conditions. In a solar thermal power generation system (Solar electricity generation system, SEGS), using a steam screw expander to construct a steam-organic working medium cascade Rankine cycle system (steam-organic Rankine cycle, SORC) can avoid overheating devices, and at relatively low The system can also guarantee high efficiency under certain temperature and pressure. For example, when the temperature of the heat source is 250°C, the power generation efficiency of the system is about 15%. In addition, when water is used as the thermal storage medium, the system can also adopt direct steam generation (DSG), which makes the solar thermal power generation system have flexible operability and excellent thermodynamic performance. However, the direct expansion solar cascade rankine cycle power generation system (DSG-SORC) based on water heat storage still faces some challenges:
1）对于单级蓄热系统，在放热过程中，蓄热罐中水的温降受到限制，可利用的温降较低。这是因为蓄热罐中的水汽化蒸发，温度逐步降低，导致螺杆膨胀机的进口压力也随之下降。而当螺杆膨胀机的运行压比低于设计值时，其效率会显著降低。比如，针对一个设计背压为0.55MPa的水蒸气螺杆膨胀机，当蓄热罐水温由250℃降至220℃时，其运行压比会由7.2降至4.2。考虑到螺杆膨胀机的内置比体积，进一步降低蓄热罐水温会导致水蒸气螺杆膨胀机严重偏离设计工况，性能急剧恶化。1) For a single-stage heat storage system, during the heat release process, the temperature drop of the water in the heat storage tank is limited, and the available temperature drop is low. This is because the water in the heat storage tank is vaporized and evaporated, and the temperature gradually decreases, resulting in a decrease in the inlet pressure of the screw expander. However, when the operating pressure ratio of the screw expander is lower than the design value, its efficiency will be significantly reduced. For example, for a steam screw expander with a design back pressure of 0.55MPa, when the water temperature of the heat storage tank drops from 250°C to 220°C, its operating pressure ratio will drop from 7.2 to 4.2. Considering the built-in specific volume of the screw expander, further reducing the water temperature of the heat storage tank will cause the steam screw expander to seriously deviate from the design working conditions, and the performance will deteriorate sharply.
2）蓄热罐水温的降低不仅对蒸汽朗肯循环也对有机朗肯循环产生不利影响。在放热过程中，不仅水蒸气螺杆膨胀机处于变工况运行，底部的有机朗肯循环也很难维持稳定运行。随着水蒸气螺杆膨胀机进口温度和压力的降低，通过螺杆膨胀机的水工质流量也在降低。中间换热器中传递给有机工质的热量将不足以驱动有机朗肯循环有效运行。尤其当有机朗肯循环采用的是透平膨胀机时，透平膨胀机比螺杆膨胀机更易受到运行工况波动的影响，这将导致系统放热过程中的不可逆损失增大。2) The reduction of water temperature in the heat storage tank not only has an adverse effect on the steam Rankine cycle but also on the organic Rankine cycle. During the exothermic process, not only the steam screw expander operates under variable conditions, but also the organic Rankine cycle at the bottom is difficult to maintain stable operation. As the inlet temperature and pressure of the water vapor screw expander decrease, the flow rate of water working through the screw expander also decreases. The heat transferred to the organic working medium in the intermediate heat exchanger will not be enough to drive the organic Rankine cycle to operate effectively. Especially when the organic Rankine cycle uses a turbo expander, the turbo expander is more susceptible to fluctuations in operating conditions than the screw expander, which will lead to increased irreversible losses during the heat release process of the system.
3）大容积的高温高压蓄热罐不利于提高系统的经济性。比如，对于一个装机容量1MWe、蓄热时长6小时，设计压力4.0 MPa,设计温度250oC、设计容积400m2的DSG-SORC系统，蓄热罐的成本大约为255万人民币，这与抛物面集热器阵列的成本是相当的。蓄热罐较高的成本与单级蓄热水罐较小的温降是密切相关的。相同蓄热能力下，较小的温降使得蓄热罐容积增大，影响DSG-SORC统的经济效益。3) Large-volume high-temperature and high-pressure heat storage tanks are not conducive to improving the economy of the system. For example, for a DSG-SORC system with an installed capacity of 1MWe, a heat storage time of 6 hours, a design pressure of 4.0 MPa, a design temperature of 250o C, and a design volume of 400m2 , the cost of the heat storage tank is about 2.55 million RMB, which is comparable to that of a parabolic surface The cost of the heater array is comparable. The higher cost of heat storage tanks is closely related to the smaller temperature drop of single-stage heat storage tanks. Under the same heat storage capacity, a small temperature drop increases the volume of the heat storage tank, which affects the economic benefits of the DSG-SORC system.
到目前为止，有关传统直膨式太阳能槽式发电系统的蓄热研究已较为广泛。为改善系统效率，两级和三级蓄热结构也已被提出。然而，在这种多级蓄热结构中，系统的工作介质（水）和蓄热介质（混凝土、相变材料、水、空气等）通常彼此分开、位于独立的单元之中，这导致系统的结构和传热换热过程比较复杂。So far, heat storage research on traditional direct expansion solar trough power generation systems has been extensive. To improve system efficiency, two-stage and three-stage thermal storage structures have also been proposed. However, in this multi-stage heat storage structure, the system’s working medium (water) and heat storage medium (concrete, phase change materials, water, air, etc.) are usually separated from each other and located in independent units, which leads to the system’s The structure and heat transfer and heat transfer process are more complicated.
实用新型内容Utility model content
为了实现在不明显增大成本的条件下，提高系统的蓄热能力，降低太阳能热发电系统的不可逆损失，本实用新型提出一种具有不同放热模式的太阳能复叠朗肯循环发电系统。In order to improve the heat storage capacity of the system and reduce the irreversible loss of the solar thermal power generation system without significantly increasing the cost, the utility model proposes a solar cascade Rankine cycle power generation system with different heat release modes.
一种具有不同放热模式的太阳能复叠朗肯循环发电系统包括由抛物面槽式集热器阵列C、高温蓄热水罐HTA、水蒸气螺杆膨胀机E、第一发电机G1、第一换热器HX1、第一水泵P1、第一阀门V1、第二阀门V2、第三阀门V3、第四阀门V4、第六阀门V6和第七阀门V7组成的蒸汽朗肯循环回路和由有机工质膨胀机T、第二发电机G2、第二换热器HX2、有机工质泵P3组成的有机朗肯循环回路；所述第一换热器HX1中一侧工质为水，另一侧工质为有机工质；所述第二换热器HX2中一侧工质为水，另一侧工质为有机工质；所述第一换热器HX1中的有机工质一侧串联在有机朗肯循环回路的有机工质泵P3的出口和有机工质膨胀机T之间；A solar cascade Rankine cycle power generation system with different heat release modes includes a parabolic trough collector array C, a high-temperature heat storage tank HTA, a steam screw expander E, a first generator G1, a first exchanger Heater HX1, the first water pump P1, the first valve V1, the second valve V2, the third valve V3, the fourth valve V4, the sixth valve V6 and the seventh valve V7 constitute the steam Rankine cycle circuit and the organic working fluid An organic Rankine cycle consisting of expander T, second generator G2, second heat exchanger HX2, and organic working medium pump P3; one side of the first heat exchanger HX1 is water, and the other side is working The working medium is an organic working medium; one side of the second heat exchanger HX2 is water, and the other side is an organic working medium; one side of the organic working medium in the first heat exchanger HX1 is connected in series to the organic working medium. Between the outlet of the organic working medium pump P3 of the Rankine cycle and the organic working medium expander T;
还包括由低温蓄热水罐LTA、第二水泵P2、第五阀门V5和节流阀TV组成的低温蓄热水罐支路；低温蓄热水罐LTA的出口连通着第二水泵P2的进口，第二水泵P2的出口和第一水泵P1的出口并联，低温蓄热水罐LTA的进口通过串联的节流阀TV和第五阀门V5连通着第一换热器HX1的水工质出口；It also includes a low-temperature hot-storage tank branch circuit composed of a low-temperature hot-storage tank LTA, a second water pump P2, a fifth valve V5, and a throttle valve TV; the outlet of the low-temperature hot-storage tank LTA is connected to the inlet of the second water pump P2 , the outlet of the second water pump P2 is connected in parallel with the outlet of the first water pump P1, and the inlet of the low-temperature heat storage tank LTA is connected to the outlet of the hydraulic medium of the first heat exchanger HX1 through the serial throttle valve TV and the fifth valve V5;
使抛物面槽式集热器阵列C、高温蓄热水罐HTA和低温蓄热水罐LTA构成以水为工质的循环回路；系统首先利用高温蓄热水罐HTA中的水汽化蒸发，驱动蒸汽朗肯循环和有机朗肯循环进行热功转换，该过程低温蓄热水罐支路不参与工作；其次，高温蓄热水罐HTA中的水经第一换热器HX1流入低温蓄热水罐LTA中，热量用于驱动有机朗肯循环工作，该过程低温蓄热水罐LTA和高温蓄热水罐HTA联合工作；Make the parabolic trough collector array C, the high-temperature hot water tank HTA and the low-temperature hot water tank LTA form a circulation loop with water as the working medium; the system first uses the water vaporization and evaporation in the high-temperature hot water tank HTA to drive the steam The rankine cycle and the organic rankine cycle perform thermal work conversion, and the low-temperature hot water storage tank branch does not participate in the work in this process; secondly, the water in the high-temperature hot water storage tank HTA flows into the low-temperature hot water storage tank through the first heat exchanger HX1 In the LTA, the heat is used to drive the organic Rankine cycle, in which the low temperature storage tank LTA and the high temperature storage tank HTA work together;
所述高温蓄热水罐HTA和低温蓄热水罐LTA的温差为100～200℃。The temperature difference between the high-temperature hot water storage tank HTA and the low-temperature hot water storage tank LTA is 100-200°C.
进一步限定的技术方案如下：Further defined technical solutions are as follows:
所述有机朗肯循环的工质为R123、R141b、R245fa、R365mfc、丁烷、戊烷、环己烷、异丁烯、HFO-1336mzz(Z)和苯中的一种。The working fluid of the organic Rankine cycle is one of R123, R141b, R245fa, R365mfc, butane, pentane, cyclohexane, isobutene, HFO-1336mzz(Z) and benzene.
所述水蒸气螺杆膨胀机E为单螺杆膨胀机、双螺杆膨胀机中的一种。The steam screw expander E is one of a single-screw expander and a twin-screw expander.
所述有机工质膨胀机T为单螺杆膨胀机、双螺杆膨胀机、涡旋膨胀机、透平膨胀机中的一种。The organic working medium expander T is one of a single-screw expander, a twin-screw expander, a scroll expander, and a turbo expander.
所述高温蓄热水罐HTA的工作温度为150℃～250℃。The working temperature of the high temperature hot water storage tank HTA is 150°C-250°C.
所述低温蓄热水罐LTA的工作温度为30℃～150℃。The working temperature of the low-temperature hot water storage tank LTA is 30°C-150°C.
在已有的技术方案中，发明专利申请‘具有两级蓄热水罐的直膨式太阳能热电联供系统’(申请号: CN201611107905.4)，公开一种具有高温蓄热水罐和低温蓄热水罐的直膨式太阳能复叠朗肯循环热电联供系统。目的之一在于提高系统发电和供热的独立性和灵活性。在实际生活中，人们的用电和用热需求不一定是同步进行的。在发明CN201611107905.4中，由于具有两级蓄热水罐，系统可以利用螺杆膨胀机单独发电，也可以利用低温级蓄热水罐单独供热或驱动有机朗肯循环发电，或发电供热同时进行。供能模式可以依据用户需求灵活调整。另外，发明CN201611107905.4中的集热器阵列与高温级蓄热水罐和低温级蓄热水罐有机结合，可将获得太阳热能直接用于发电，也可将热能储存于高温级蓄热水罐中，还能将热能储存于低温级蓄热水罐中，实现梯级集热。在低的太阳辐照条件下，可将集热器阵列输送到低温级蓄热水罐中，达到高效利用低强度太阳辐照的目的。Among the existing technical solutions, the invention patent application 'direct expansion solar cogeneration system with two-stage hot water storage tank' (application number: CN201611107905.4) discloses a Direct expansion solar cascade rankine cycle combined heat and power system for hot water tank. One of the purposes is to improve the independence and flexibility of power generation and heat supply of the system. In real life, people's demand for electricity and heat is not necessarily synchronized. In the invention CN201611107905.4, due to the two-stage heat storage tank, the system can use the screw expander to generate electricity alone, or use the low-temperature heat storage tank to supply heat alone or drive the organic Rankine cycle to generate electricity, or generate electricity and heat at the same time conduct. The energy supply mode can be flexibly adjusted according to user needs. In addition, the heat collector array in the invention CN201611107905.4 is organically combined with the high-temperature water storage tank and the low-temperature water storage tank, so that the solar heat can be directly used for power generation, and the heat energy can also be stored in the high-temperature water storage tank. In the tank, heat energy can also be stored in the low-temperature heat storage tank to realize cascade heat collection. Under the condition of low solar radiation, the collector array can be transported to the low-temperature heat storage tank to achieve the purpose of efficiently utilizing low-intensity solar radiation.
与发明申请CN201611107905.4相比，本实用新型在结构和工作原理上有着显著创新性，体现在以下方面：Compared with the invention application CN201611107905.4, the utility model has significant innovation in structure and working principle, which is reflected in the following aspects:
（1） 本实用新型的系统处于第一种放热模式时，高温蓄热水罐HTA中水的质量是近似不变，是变温过程；系统处于第二种放热模式时，高温蓄热水罐HTA和低温蓄热水罐LTA温度近似不变，是变质量过程。这种变温过程和变质量过程有机结合的放热模式，与复叠式水蒸气-有机朗肯循环形成了完美匹配。该技术方案尚未见类似报道，具有明显的方法创新。(1) When the system of the utility model is in the first exothermic mode, the quality of the water in the high-temperature hot water storage tank HTA is approximately constant, which is a process of variable temperature; when the system is in the second exothermic mode, the high-temperature hot water storage The temperature of the tank HTA and the low-temperature hot water storage tank LTA is approximately constant, which is a variable mass process. The exothermic mode of this organic combination of variable temperature process and variable mass process forms a perfect match with the cascade water vapor-organic Rankine cycle. This technical solution has not been reported similarly yet, and has obvious method innovations.
（2） 发明专利申请CN201611107905.4中，当系统需要利用储存的热量进行发电时，不论是高温级蓄热水罐驱动顶部水蒸气朗肯循环发电，还是低温级蓄热水罐驱动底部有机朗肯循环发电，水罐的温度都会逐渐降低。水蒸气朗肯循环或有机朗肯循环发电时刻处于变工况运行状态。这不利于保证系统发电的稳定性。而本实用新型中，当系统处于第二种放热模式时，高温蓄热水罐HTA、低温蓄热水罐LTA与第一换热器HX1、节流阀TV联合工作，具有明显的结构创新。同时，当系统处于第二种放热模式时，由于高温蓄热水罐HTA和低温蓄热水罐LTA温度恒定，第一换热器HX1的进出口水温恒定，因此底部有机朗肯循环发电能够处于稳定的发电状态。而且第二种放热模式在不改变高温蓄热水罐HTA罐体结构和容量的条件下，可以极大提高系统的蓄热能力，使系统更具经济性。比如，当系统额定发电功率为1MW，高温蓄热水罐HTA的工作温度为250℃，体积为275m3时，增加一个相同体积的低温蓄热水罐LTA可以使得系统的蓄热容量增大至少6倍以上，而额外增加的集热场和低温蓄热水罐LTA的投资回收期仅为1-3年。(2) In the invention patent application CN201611107905.4, when the system needs to use the stored heat to generate electricity, whether it is a high-temperature storage tank driving the top water vapor Rankine cycle power generation, or a low-temperature storage tank driving the bottom organic Langine If the power cycle is activated, the temperature of the water tank will gradually decrease. The steam Rankine cycle or organic Rankine cycle power generation is always in the state of variable working conditions. This is not conducive to ensuring the stability of system power generation. However, in this utility model, when the system is in the second heat release mode, the high-temperature hot water storage tank HTA, the low-temperature hot water storage tank LTA work together with the first heat exchanger HX1 and the throttle valve TV, which has obvious structural innovations . At the same time, when the system is in the second heat release mode, since the temperature of the high temperature storage tank HTA and the low temperature storage tank LTA are constant, the water temperature at the inlet and outlet of the first heat exchanger HX1 is constant, so the bottom organic Rankine cycle power generation can In a stable power generation state. Moreover, the second heat release mode can greatly improve the heat storage capacity of the system without changing the structure and capacity of the high-temperature hot water storage tank HTA tank, making the system more economical. For example, when the rated generating power of the system is 1MW, the operating temperature of the high-temperature hot water storage tank HTA is 250°C, and the volume is 275m3 , adding a low-temperature hot water storage tank LTA of the same volume can increase the heat storage capacity of the system by at least 6 times, and the payback period for additional heat collectors and low temperature storage tanks LTA is only 1-3 years.
附图说明Description of drawings
图1为本实用新型的示意图。Fig. 1 is the schematic diagram of the utility model.
具体实施方式Detailed ways
下面结合附图，通过实施例对本实用新型作进一步地描述。Below in conjunction with accompanying drawing, the utility model is described further through embodiment.
实施例1Example 1
参见图1，一种具有不同放热模式的太阳能复叠朗肯循环发电系统包括由抛物面槽式集热器阵列C、高温蓄热水罐HTA、水蒸气螺杆膨胀机E、第一发电机G1、第一换热器HX1、第一水泵P1、第一阀门V1、第二阀门V2、第三阀门V3、第四阀门V4、第六阀门V6和第七阀门V7组成的蒸汽朗肯循环回路和由有机工质膨胀机T、第二发电机G2、第二换热器HX2、有机工质泵P3组成的有机朗肯循环回路；所述第一换热器HX1中一侧工质为水，另一侧工质为有机工质；所述第二换热器HX2中一侧工质为水，另一侧工质为有机工质；第一换热器HX1中的有机工质一侧串联在有机朗肯循环回路的有机工质泵P3的出口和有机工质膨胀机T之间。Referring to Figure 1, a solar cascade Rankine cycle power generation system with different heat release modes includes a parabolic trough collector array C, a high-temperature heat storage tank HTA, a steam screw expander E, and a first generator G1 , the first heat exchanger HX1, the first water pump P1, the first valve V1, the second valve V2, the third valve V3, the fourth valve V4, the sixth valve V6 and the seventh valve V7 constitute the steam Rankine cycle loop and An organic Rankine cycle loop composed of an organic working medium expander T, a second generator G2, a second heat exchanger HX2, and an organic working medium pump P3; one side of the first heat exchanger HX1 is water, The working medium on the other side is an organic working medium; the working medium on one side of the second heat exchanger HX2 is water, and the working medium on the other side is an organic working medium; one side of the organic working medium in the first heat exchanger HX1 is connected in series Between the outlet of the organic working medium pump P3 of the organic Rankine cycle and the organic working medium expander T.
还包括由低温蓄热水罐LTA、第二水泵P2、第五阀门V5和节流阀TV组成的低温蓄热水罐支路；低温蓄热水罐LTA的出口连通着第二水泵P2的进口，第二水泵P2的出口和第一水泵P1的出口并联，低温蓄热水罐LTA的进口通过串联的节流阀TV和第五阀门V5连通着第一换热器HX1的水工质出口。It also includes a low-temperature hot-storage tank branch circuit composed of a low-temperature hot-storage tank LTA, a second water pump P2, a fifth valve V5, and a throttle valve TV; the outlet of the low-temperature hot-storage tank LTA is connected to the inlet of the second water pump P2 , the outlet of the second water pump P2 is connected in parallel with the outlet of the first water pump P1, and the inlet of the low-temperature heat storage tank LTA is connected to the hydraulic medium outlet of the first heat exchanger HX1 through the serial throttle valve TV and the fifth valve V5.
水蒸气螺杆膨胀机E为单螺杆膨胀机，有机工质膨胀机T为单螺杆膨胀机，有机朗肯循环的工质为R123。The steam screw expander E is a single-screw expander, the organic working medium expander T is a single-screw expander, and the working medium of the organic Rankine cycle is R123.
高温蓄热水罐HTA的工作温度为150℃～250℃，低温蓄热水罐LTA的工作温度为30℃～150℃。The working temperature of the high-temperature hot water storage tank HTA is 150°C-250°C, and the working temperature of the low-temperature hot water storage tank LTA is 30°C-150°C.
系统主要工作模式如下：The main working modes of the system are as follows:
（1）在阴天或晚上时，系统利用高温蓄热水罐HTA和低温蓄热水罐LTA实现发电，依次进行两种放热模式。首先，在第一种放热模式下，利用高温蓄热水罐HTA的热量驱动复叠式水蒸气-有机工质循环发电。此时第一阀门V1、第三阀门V3、第四阀门V4、第七阀门V7打开，其余阀门关闭。第一水泵P1和有机工质泵P3运行，第二水泵P2关闭。高温蓄热水罐HTA的饱和水蒸气进入水蒸汽螺杆膨胀机E，膨胀做功，水蒸汽螺杆膨胀机E出口尾气进入第一换热器HX1，实现冷凝，并将热量传递给有机工质，经过第一换热器HX1冷凝后的液态水，进入第一水泵P1，加压，重新进入高温蓄热水罐HTA。有机工质从第一换热器HX1获得热量，产生高压气体，进入有机工质膨胀机T，膨胀做功，有机工质膨胀机T出口工质进入第二换热器HX2，实现冷凝，冷凝后的液态有机工质进入第一换热器HX1，重新吸热蒸发。在该模式中，低温蓄热水罐LTA不参与工作。而高温蓄热水罐HTA由于水的蒸发吸热作用，温度和压力逐渐降低。为了防止水蒸汽螺杆膨胀机E和有机工质膨胀机T严重偏离设计工况，保证高效的热功转换，高温蓄热水罐HTA的温降是受限制的，一般为20-30℃左右。其次，在第一种放热模式完成后，进入第二种放热模式。高温蓄热水罐HTA和低温蓄热水罐LTA联合工作，底部有机工质循环发电。第二阀门V2和第五阀门V5打开，其余阀门关闭。有机工质泵P3运行，其余水泵关闭。液态水从高温蓄热水罐HTA流入第二换热器HX2 并将热量传递给有机工质，冷却后高压水经过节流阀TV进入低温蓄热水罐LTA。有机工质从第一换热器HX1获得热量，产生高压气体，进入有机工质膨胀机T，膨胀做功，有机工质膨胀机T出口工质进入第二换热器HX2，实现冷凝，冷凝后的液态有机工质进入第一换热器HX1，重新吸热蒸发。在第二种放热模式中，高温蓄热水罐HTA中的水容量不断减少，低温蓄热水罐LTA的水容量不断升高。由于高温蓄热水罐HTA和低温蓄热水罐LTA的温度相对稳定，因此有机工质膨胀机T处于恒定的运行工况中。高温蓄热水罐HTA和低温蓄热水罐LTA的温差可达100℃以上，远高于第一种放热模式中释放的热量。(1) On cloudy days or at night, the system utilizes the high-temperature hot water storage tank HTA and the low-temperature hot water storage tank LTA to generate electricity, and performs two heat release modes in sequence. First, in the first heat release mode, the heat of the high temperature storage tank HTA is used to drive the cascade steam-organic working medium cycle to generate electricity. At this time, the first valve V1, the third valve V3, the fourth valve V4, and the seventh valve V7 are opened, and the other valves are closed. The first water pump P1 and the organic working medium pump P3 are running, and the second water pump P2 is off. The saturated water vapor of the high-temperature hot water storage tank HTA enters the steam screw expander E to perform work. The exhaust gas from the outlet of the steam screw expander E enters the first heat exchanger HX1 to realize condensation and transfer heat to the organic working medium. The liquid water condensed by the first heat exchanger HX1 enters the first water pump P1, is pressurized, and re-enters the high-temperature heat storage tank HTA. The organic working fluid obtains heat from the first heat exchanger HX1, generates high-pressure gas, enters the organic working fluid expander T, and expands to do work. The outlet of the organic working fluid expander T enters the second heat exchanger HX2 to realize condensation. The liquid organic working medium enters the first heat exchanger HX1, absorbs heat and evaporates again. In this mode, the low temperature storage tank LTA does not participate in the work. However, the temperature and pressure of the high-temperature hot water storage tank HTA gradually decrease due to the heat-absorbing effect of water evaporation. In order to prevent the water vapor screw expander E and the organic working medium expander T from seriously deviating from the design conditions and ensure efficient thermal power conversion, the temperature drop of the high temperature storage tank HTA is limited, generally around 20-30°C. Second, after the first heat release mode is completed, enter the second heat release mode. The high-temperature hot water storage tank HTA and the low-temperature hot water storage tank LTA work together, and the organic working fluid at the bottom circulates to generate electricity. The second valve V2 and the fifth valve V5 are opened, and the remaining valves are closed. The organic working medium pump P3 runs, and the other water pumps are closed. Liquid water flows into the second heat exchanger HX2 from the high-temperature heat storage tank HTA and transfers heat to the organic working medium. After cooling, the high-pressure water enters the low-temperature heat storage tank LTA through the throttle valve TV. The organic working fluid obtains heat from the first heat exchanger HX1, generates high-pressure gas, enters the organic working fluid expander T, and expands to do work. The outlet of the organic working fluid expander T enters the second heat exchanger HX2 to realize condensation. The liquid organic working medium enters the first heat exchanger HX1, absorbs heat and evaporates again. In the second heat release mode, the water capacity in the high-temperature hot water storage tank HTA keeps decreasing, and the water capacity in the low-temperature hot water storage tank LTA keeps increasing. Since the temperatures of the high-temperature heat storage tank HTA and the low-temperature heat storage tank LTA are relatively stable, the organic working medium expander T is in a constant operating condition. The temperature difference between the high-temperature hot water storage tank HTA and the low-temperature hot water storage tank LTA can reach more than 100°C, which is much higher than the heat released in the first heat release mode.
（2）在白天具有太阳能辐照时如大于300W/m2，系统处于集热和发电同时进行状态。第一阀门V1、第三阀门V3、第四阀门V4、第六阀门V6打开，其余阀门关闭。第一水泵P1、第二水泵P2和有机工质泵P3均运行。高温蓄热水罐HTA的饱和水蒸气进入水蒸汽螺杆膨胀机E，膨胀做功，水蒸汽螺杆膨胀机E出口尾气进入第一换热器HX1，实现冷凝，并将热量传递给有机工质，经过第一换热器HX1冷凝后的液态水，进入第一水泵P1，加压进入抛物面槽式集热器阵列C，然后进入高温蓄热水罐HTA。通过低温蓄热水罐LTA的液态水经第二水泵P2加压，也进入抛物面槽式集热器阵列C。有机工质从第一换热器HX1获得热量，产生高压气体，进入有机工质膨胀机T，膨胀做功，有机工质膨胀机T出口工质进入第二换热器HX2，实现冷凝，冷凝后的液态有机工质进入第一换热器HX1，重新吸热蒸发。根据太阳辐照的强弱，第二水泵P2的流量可以调整。抛物面槽式集热器阵列C出口的水工质可以处于液态、气液两相或饱和气态。在强辐照条件下，抛物面槽式集热器阵列C收集的热量不仅可以用于驱动复叠水蒸气-有机朗肯循环系统发电，还可以储存在高温蓄热水罐HTA中。(2) If the solar radiation is greater than 300W/m2 during the day, the system is in the state of heat collection and power generation at the same time. The first valve V1, the third valve V3, the fourth valve V4, and the sixth valve V6 are opened, and the other valves are closed. The first water pump P1, the second water pump P2 and the organic working medium pump P3 are all in operation. The saturated water vapor of the high-temperature hot water storage tank HTA enters the steam screw expander E, and expands to do work. The exhaust gas from the outlet of the steam screw expander E enters the first heat exchanger HX1 to realize condensation and transfer heat to the organic working medium. The liquid water condensed by the first heat exchanger HX1 enters the first water pump P1, is pressurized and enters the parabolic trough heat collector array C, and then enters the high-temperature hot water storage tank HTA. The liquid water passing through the low-temperature heat storage tank LTA is pressurized by the second water pump P2, and also enters the parabolic trough heat collector array C. The organic working fluid obtains heat from the first heat exchanger HX1, generates high-pressure gas, enters the organic working fluid expander T, and expands to do work. The outlet of the organic working fluid expander T enters the second heat exchanger HX2 to realize condensation. The liquid organic working fluid enters the first heat exchanger HX1, absorbs heat and evaporates again. According to the intensity of solar radiation, the flow rate of the second water pump P2 can be adjusted. The hydraulic fluid at the outlet C of the parabolic trough collector array can be in liquid state, gas-liquid two-phase or saturated gas state. Under strong irradiation conditions, the heat collected by the parabolic trough collector array C can not only be used to drive the cascade steam-organic Rankine cycle system to generate electricity, but also can be stored in the high-temperature heat storage tank HTA.
当系统处于设计工况时，相关参数如下：When the system is in the design condition, the relevant parameters are as follows:
1.系统额定发电功率为1MW；1. The rated generating power of the system is 1MW;
2.高温蓄热水罐HTA的温度为250℃，低温蓄热水罐LTA的温度为44℃；2. The temperature of the high-temperature hot water storage tank HTA is 250°C, and the temperature of the low-temperature hot water storage tank LTA is 44°C;
3.水蒸气在第一换热器HX1中的冷凝温度为152℃；3. The condensation temperature of water vapor in the first heat exchanger HX1 is 152°C;
4.有机工质为R123；4. The organic working fluid is R123;
5.R123在第一换热器HX1中的蒸发温度为147℃；5. The evaporation temperature of R123 in the first heat exchanger HX1 is 147°C;
6.R123在第二换热器HX2中的冷凝温度为35℃；6. The condensation temperature of R123 in the second heat exchanger HX2 is 35°C;
7.水蒸气螺杆膨胀机E的效率为75%；7. The efficiency of steam screw expander E is 75%;
8.透平膨胀机T的效率为80%；8. The efficiency of the turbo expander T is 80%;
9.第一水泵P1、第二水泵P2和有机工质泵P3效率为65%；9. The efficiency of the first water pump P1, the second water pump P2 and the organic working medium pump P3 is 65%;
10.高温蓄热水罐HTA和低温蓄热水罐LTA容积相同，为275m3。10. The volume of the high temperature storage tank HTA and the low temperature storage tank LTA is the same, 275m3 .
根据以上参数，可计算得到顶部水蒸气朗肯循环效率为11.5%，净输出电功率（扣除泵功）为470kW；底部有机朗肯循环效率为15.1%，净输出电功率为530kW；复叠朗肯循环整体热功转换效率为24.7%，净输出电功率为1000 kW。According to the above parameters, it can be calculated that the top water vapor Rankine cycle efficiency is 11.5%, and the net output electric power (after deducting the pump work) is 470kW; the bottom organic Rankine cycle efficiency is 15.1%, and the net output electric power is 530kW; the cascade Rankine cycle The overall thermal power conversion efficiency is 24.7%, and the net output electric power is 1000 kW.
当系统处于第一种放热模式时，高温蓄热水罐HTA的温度由250℃（对应饱和压力为3.98 MPa）降低为由230℃（对应饱和压力为2.79 MPa），即设计温降为20℃。根据高温蓄热水罐HTA容积和温降，可计算出第一种放热模式下，系统可持续发电1小时，即发电能力为1MWh。When the system is in the first exothermic mode, the temperature of the high-temperature hot water storage tank HTA is reduced from 250°C (corresponding to a saturation pressure of 3.98 MPa) to 230°C (corresponding to a saturation pressure of 2.79 MPa), that is, the design temperature drop is 20 ℃. According to the volume and temperature drop of the high-temperature hot water storage tank HTA, it can be calculated that under the first heat release mode, the system can continue to generate electricity for 1 hour, that is, the power generation capacity is 1MWh.
第一换热器HX1中水的进口温度为230℃，出口温度44℃（低温蓄热水罐温度），流量为4.43 kg/s；R123的进口温度为35℃，出口温度为147℃（饱和气态） 流量为15.86kg/s。根据高温蓄热水罐HTA容积、水流量和经过第一换热器HX1后水的温降，可计算出在第二种放热模式下，有机朗肯循环可持续发电15.7小时，发电能力为8.4MWh。第二种放热模式下的发电能力是第一种放热模式下发电能力的8.4倍，这表明第二种放热模式可极大提高系统的热力性能。The inlet temperature of water in the first heat exchanger HX1 is 230°C, the outlet temperature is 44°C (the temperature of the low-temperature hot water storage tank), and the flow rate is 4.43 kg/s; the inlet temperature of R123 is 35°C, and the outlet temperature is 147°C (saturated Gaseous state) The flow rate is 15.86kg/s. According to the volume of the high-temperature hot water storage tank HTA, the water flow rate and the temperature drop of the water after passing through the first heat exchanger HX1, it can be calculated that in the second heat release mode, the organic Rankine cycle can continue to generate electricity for 15.7 hours, and the power generation capacity is 8.4MWh. The power generation capacity of the second heat release mode is 8.4 times that of the first heat release mode, which indicates that the second heat release mode can greatly improve the thermal performance of the system.
在经济性能方面，第二种放热模式下所释放的热量需要通过抛物面槽式集热器阵列C加以收集。与单一拥有第一种放热模式的太阳能热发电系统相比，本实用新型的系统需要更大的集热面积，以支撑第二种放热模式。以辐照强度750W/m2，日照时长为6.5小时为参考值，为了在白天收集足够的热量以保证第二种放热模式的正常运转，则需要增加集热面积约为16484m2。以每平方米300人民币的集热场价格估算，则需增加投资495万元。以拉萨为例，第二种放热模式下16484m2的集热面积可驱动有机朗肯循环每年产生电量2787323kWh。以1.15元每度电的价格计算，该部分的投资回收期约为1.6年。由此可见，第二种放热模式虽然增加了集热面积，但由于蓄热能力和年发电量提高明显，该部分的投资回收期远低于传统太阳能热发电站的回收期（5年或更长），这利于提高本实用新型系统的整体经济性能。In terms of economic performance, the heat released in the second heat release mode needs to be collected by the parabolic trough collector array C. Compared with the single solar thermal power generation system with the first heat release mode, the system of the present invention requires a larger heat collection area to support the second heat release mode. Taking the irradiance intensity of 750W/m2 and the sunshine duration of 6.5 hours as reference values, in order to collect enough heat during the day to ensure the normal operation of the second heat release mode, it is necessary to increase the heat collection area by about 16484m2 . Based on the price of the collector field at RMB 300 per square meter, an additional investment of RMB 4.95 million is required. Taking Lhasa as an example, the heat collection area of 16484m2 in thesecond heat release mode can drive the organic Rankine cycle to generate 2787323kWh of electricity per year. Calculated at the price of 1.15 yuan per kilowatt-hour, the payback period of this part is about 1.6 years. It can be seen that although the second heat release mode increases the heat collection area, due to the obvious increase in heat storage capacity and annual power generation, the payback period of this part is much lower than that of traditional solar thermal power plants (5 years or longer), which is conducive to improving the overall economic performance of the utility model system.
实施例2Example 2
一种具有不同放热模式的太阳能复叠朗肯循环发电系统的结构和工作原理同实施例1。The structure and working principle of a solar cascaded Rankine cycle power generation system with different heat release modes are the same as those in Embodiment 1.
当系统处于设计工况时，相关参数如下：When the system is in the design condition, the relevant parameters are as follows:
1.系统额定发电功率为1MW；1. The rated generating power of the system is 1MW;
2.高温蓄热水罐HTA的温度为250℃；低温蓄热水罐LTA的温度为109℃2. The temperature of the high-temperature hot water storage tank HTA is 250°C; the temperature of the low-temperature hot water storage tank LTA is 109°C
3.水蒸气在第一换热器HX1中的冷凝温度为161℃；3. The condensation temperature of water vapor in the first heat exchanger HX1 is 161°C;
4.有机工质为苯；4. The organic working medium is benzene;
5.苯在第一换热器HX1中的蒸发温度为156℃；5. The evaporation temperature of benzene in the first heat exchanger HX1 is 156°C;
6.苯在第二换热器HX2中的冷凝温度为35℃；6. The condensation temperature of benzene in the second heat exchanger HX2 is 35°C;
7.水蒸气螺杆膨胀机E的效率为75%；7. The efficiency of steam screw expander E is 75%;
8.透平膨胀机T的效率为80%；8. The efficiency of the turbo expander T is 80%;
9.第一水泵P1、第二水泵P2和有机工质泵P3效率为65%；9. The efficiency of the first water pump P1, the second water pump P2 and the organic working medium pump P3 is 65%;
10.高温蓄热水罐HTA和低温蓄热水罐LTA容积相同，为275m3。10. The volume of the high temperature storage tank HTA and the low temperature storage tank LTA is the same, 275m3 .
根据以上参数，可计算得到顶部水蒸气朗肯循环效率为10.8%，净输出电功率（扣除泵功）为410kW；底部有机朗肯循环效率为17.5%，净输出电功率为590kW；复叠朗肯循环整体热功转换效率为26.4%，净输出电功率为1000 kW。According to the above parameters, it can be calculated that the top water vapor Rankine cycle efficiency is 10.8%, and the net output electric power (after deducting the pump work) is 410kW; the bottom organic Rankine cycle efficiency is 17.5%, and the net output electric power is 590kW; the cascade Rankine cycle The overall thermal power conversion efficiency is 26.4%, and the net output electric power is 1000 kW.
当系统处于第一种放热模式时，与实施例1相同，系统可持续发电1小时，发电能力为1MWh。When the system is in the first heat release mode, the same as in embodiment 1, the system can generate electricity continuously for 1 hour, and the power generation capacity is 1MWh.
当系统处于第二种放热模式时，第一换热器HX1中水的进口温度为230℃，出口温度109℃（低温蓄热水罐温度），流量为6.32 kg/s；苯的进口温度为35℃，出口温度为156℃（饱和气态） 流量为5.92kg/s。有机朗肯循环可持续发电11.0小时，发电能力为6.5MWh，第二种放热模式下的发电能力是第一种放热模式下发电能力的6.5倍。When the system is in the second exothermic mode, the inlet temperature of water in the first heat exchanger HX1 is 230°C, the outlet temperature is 109°C (the temperature of the low-temperature hot water storage tank), and the flow rate is 6.32 kg/s; the inlet temperature of benzene The temperature is 35°C, the outlet temperature is 156°C (saturated gas state), and the flow rate is 5.92kg/s. The organic Rankine cycle can generate electricity continuously for 11.0 hours, with a power generation capacity of 6.5MWh. The power generation capacity under the second heat release mode is 6.5 times that of the first heat release mode.
与实施例1相同，以辐照强度750W/m2，日照时长为6.5小时为参考值，为了在白天收集足够的热量以保证第二种放热模式的正常运转，需要增加集热面积约为11392m2，投资额为342万元。在拉萨地区，第二种放热模式下每年产生电量2091388kWh，以1.15元每度电的价格计算，该部分的投资回收期约为1.5年。Same as Example 1, taking the irradiance intensity of 750W/m2 and the sunshine duration of 6.5 hours as reference values, in order to collect enough heat during the day to ensure the normal operation of the second heat release mode, it is necessary to increase the heat collection area by about 11392m2. The investment amount is 3.42 million yuan. In the Lhasa area, the second heat release mode generates 2,091,388kWh of electricity per year. Calculated at a price of 1.15 yuan per kilowatt-hour, the payback period for this part is about 1.5 years.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720901389.6UCN207064169U (en) | 2017-07-24 | 2017-07-24 | A kind of solar energy overlapping Rankine cycle electricity generation system with different Heat release modes |
| Application Number | Priority Date | Filing Date | Title |
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| CN201720901389.6UCN207064169U (en) | 2017-07-24 | 2017-07-24 | A kind of solar energy overlapping Rankine cycle electricity generation system with different Heat release modes |
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| Application Number | Title | Priority Date | Filing Date |
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