Organic Rankine cycle power generation system adopting phase change heat exchanger

Abstract

The invention relates to an organic Rankine cycle power generation system which comprises an internal circulation steam boiler and an organic Rankine cycle power generation unit, and the internal circulation steam boiler comprises a phase change boiler body and a phase change heat exchanger. The organic Rankine cycle generator set comprises an organic working medium circulating pump, a coal economizer, a phase change heat exchanger, an organic working medium gas turbine and an organic working medium condenser, water vapor generated by the phase change boiler body is fed into the phase change heat exchanger to heat a gaseous organic working medium fed by the coal economizer, and generated condensed water returns to the phase change boiler body through a circulating water pump; a gaseous organic working medium is heated by water vapor in the phase change heat exchanger to form an overheated organic working medium, the overheated organic working medium enters the organic working medium gas turbine to drag the organic working medium generator to generate electricity, dead steam exhausted from the organic working medium gas turbine is fed into the economizer through the organic working medium condenser and the organic working medium circulating pump, and a waste heat source is cooled through the phase change boiler body and the economizer and then enters the phase change heat exchanger. Corresponding products are obtained or discharged as three wastes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic Rankine cycle power generation, and particularly relates to an organic Rankine cycle power generation system using a phase change heat exchanger. BACKGROUND

[0002] In the production processes of steel plants, oil refineries, cement plants and the like, waste gas, waste steam, waste liquid and the like products with thermal energy, pressure energy or combustible components are often generated; in many chemical processes, in addition to the physical latent heat carried by some intermediate or direct products, chemical reaction heat is also accompanied. The energy carried in the above processes is collectively referred to as residual energy, commonly known as waste heat. The waste heat resource refers to the part of energy that can be recovered or reused in the production process under the current technical conditions, but has not been fully and effectively utilized. It is of great significance to recover this part of waste heat resource for heating or low-temperature power generation. The thermodynamic cycle of low-temperature waste heat power generation is mainly divided into two categories: water vapor Rankine cycle and organic Rankine cycle, and the main differences are as follows:

[0003] First, the water vapor Rankine cycle uses water as the working medium, and the water absorbs heat in the waste heat boiler to generate steam, which enters the steam turbine to expand and do work to output power; while the organic Rankine cycle uses a low-boiling-point working medium to absorb the heat of the waste heat medium to vaporize, which enters the gas turbine to expand and do work to complete the heat-electricity conversion process;

[0004] Second, the water vapor Rankine cycle system must be provided with a soft water system for removing calcium and magnesium ions, and in order to prevent the corrosion of dissolved oxygen in water to the pipeline and equipment, the feed water must also be subjected to strict deaeration treatment; while the organic Rankine cycle does not need these auxiliary systems, and the system structure is relatively simple;

[0005] Third, in the low-temperature waste heat temperature range of waste heat recovery, due to the low evaporation temperature of the working medium, the evaporation pressure of the water vapor Rankine cycle is much lower than that of the organic Rankine cycle;

[0006] Fourth, the cold end (condenser) of the water vapor Rankine cycle is in a vacuum state (the absolute pressure is generally 0.03-0.05 bar), and the specific volume of the cold-end water vapor is much larger than that of the organic working medium. In order to discharge non-condensable gases, a water jet air ejector or the like is needed to maintain the vacuum of the condenser, and the low-pressure cylinder of the steam turbine needs a larger flow area. The low-pressure cylinder of the steam turbine and the condenser of the cold end are large and consume a lot of materials, increasing the cost of the corresponding equipment; while the gas turbine and the condenser of the organic Rankine cycle operate under positive pressure, and the specific volume of the organic working medium at the cold end is much smaller than that of the steam turbine. The flow area of the low-pressure cylinder of the organic Rankine cycle turbine is small, and air cannot leak in, so a vacuum maintenance system is not needed, and the volume of the turbine and the consumption of steel are greatly reduced;

[0007] Fifth, the performance of water vapor Rankine cycle and R245fa organic Rankine cycle waste heat power generation can be compared, it can be seen that in the water vapor Rankine cycle waste heat boiler, the heat absorption of water in the evaporation section accounts for a large proportion, and the heat absorption in the preheating section (economizer) is small; while in the organic Rankine cycle waste heat boiler, the heat absorption of low-boiling-point working medium in the preheating section accounts for a higher proportion. Therefore, the organic Rankine cycle system can reduce the final exhaust temperature of waste heat and recover more heat, and its turbine output power can reach more than twice that of the water vapor Rankine cycle in the appropriate temperature range (80-250℃). Obviously, compared with the water vapor Rankine cycle system, the ORC system has the advantages of simple structure, appropriate working pressure, high waste heat recovery efficiency, etc., and is especially suitable for the recovery and utilization of medium and low temperature waste heat;

[0008] Sixth, in order to prevent the erosion effect of water droplets on the blades when the humidity of the last stage steam of the steam turbine is too large, the turbine inlet steam is required to have a certain degree of superheat. In the water vapor Rankine waste heat boiler, a superheated steam heating section must be set, which leads to a relatively complex structure of the waste heat boiler. In addition, the convective heat transfer coefficient of water in the superheated steam state is low, so the required heat transfer area is large. For the organic Rankine cycle using dry fluid as the circulating working medium, the working medium can enter the turbine to expand and do work in the saturated steam state under the evaporation pressure. The heat transfer coefficient of the working medium in the waste heat boiler is large, which simplifies the structure of the waste heat boiler and saves the investment of the superheater.

[0009] At present, the waste heat boiler in the water vapor Rankine cycle adopts open cycle process, that is, after desalination and deaeration by water treatment equipment, the water is pumped into the water circulation loop of the boiler to supplement the steam-water loss in the water circulation process of the waste heat boiler. During the operation of the waste heat boiler, scale and oxygen corrosion will inevitably occur in the barrel, steam-water separator and convective heat transfer surface. Scale and oxygen corrosion are two core problems that threaten the safe and economic operation of traditional waste heat boilers. They often promote each other, forming a vicious cycle of "scaling-corrosion-more serious scaling", which must be fundamentally avoided through the "strict deaeration + scale prevention + water quality adjustment" three-in-one strategy. The pipe explosion accident of the convective heat transfer surface of the waste heat boiler is classified as a disaster level according to the danger and harm classification.

[0010] The scale formation of waste heat steam boiler is a complex physical and chemical process, and the main formation mechanism is as follows: the calcium, magnesium and other hardness ions in the boiler feed water and the oxygen dissolved in the feed water are difficult to be completely removed by the water treatment equipment, and are precipitated due to the decrease of solubility, chemical reaction and concentration during the heating process of the waste heat boiler, to form solid deposits such as insoluble carbonates, sulfates or silicates, which are attached to the tube wall of the convection heat exchange surface and gradually accumulate into scale; even if the waste heat boiler feed water is deoxidized by the deaerator, a small amount of dissolved oxygen cannot be completely removed and is brought into the water circulation system of the waste heat boiler, resulting in corrosion of the boiler metal heating surface and generation of oxides. Many factors such as poor water quality, failure of water treatment equipment, non-standard management, improper selection of reagent, and oxides generated by corrosion of the boiler metal heating surface can comprehensively aggravate the scale formation and under-deposit corrosion, form a vicious cycle, affect the safe and economic operation of the waste heat power station boiler, and even cause major safety accidents.

[0011] According to industrial statistics, more than 80% of the steam boiler accidents are related to poor water quality. Good water treatment can prolong the service life of the boiler by two to three times and save energy by 10% to 20%. The safe and economic operation of the water treatment equipment is the basic guarantee for the safe and economic operation of the boiler.

[0012] In addition, when the steam generated by the waste heat boiler is used as a heat source for other production processes, there is a problem of mismatch between the steam production capacity of the waste heat boiler and the heat load: if the steam production capacity of the waste heat boiler is too much, it needs to be vented or matched with energy storage facilities; if the steam production capacity is small, additional heat supplement equipment needs to be added, and the system heat balance organization is not easy.

[0013] Therefore, how to integrate the characteristics of water vapor Rankine cycle and organic Rankine cycle, retain the advantages of water as a waste heat recovery medium and organic working fluid as a Rankine cycle power generation medium, solve the problems of scale formation and oxygen corrosion in the waste heat boiler, ensure the stability and cleanliness of the water quality in the phase change boiler body, and quickly realize the system heat balance, so as to achieve the safe, economic and high-efficiency heat transfer of the overall optimization of the Rankine cycle power generation system, is worth in-depth study by the practitioners in the waste heat recovery industry. SUMMARY

[0014] The purpose of the present application is to retain the advantages of water as a waste heat recovery medium and organic working fluid as a Rankine cycle power generation medium, utilize the phase change heat exchanger technology of clean water closed loop circulation to efficiently transfer waste heat for organic Rankine cycle power generation, and solve the technical problem of scale formation and oxygen corrosion on the heating surface of the phase change boiler body. In addition, by utilizing the high heat absorption capacity of the low-boiling-point working fluid in the organic Rankine cycle in the preheating section (i.e. the coal economizer), the coal economizer can effectively reduce the final discharge temperature of the waste heat source, thereby recovering more waste heat, and providing reliable protection for the safe, stable and efficient operation of the entire combined cycle generator set.

[0015] The object of the present application is achieved by the following measures:

[0016] The organic Rankine cycle power generation system with phase change heat exchanger, characterized in that: the organic Rankine cycle power generation system comprises an internal circulation steam boiler and an organic Rankine cycle power generation unit, the internal circulation steam boiler comprises a phase change boiler body 3, a steam-water separator 4 and a phase change heat exchanger 7, the organic Rankine cycle power generation unit comprises an organic working medium circulating pump 15, an economizer 16, the phase change heat exchanger 7, an organic working medium gas turbine 13, an organic working medium condenser 14 and connecting pipelines thereof, and the internal circulation steam boiler and the organic Rankine cycle power generation unit form the organic Rankine cycle power generation system through the phase change heat exchanger 7,

[0017] The steam-water mixture produced by the phase change boiler body 3 in contact with the waste heat source 2 enters the steam-water separator 4, and steam-water separation is performed in the steam-water separator 4, the separated liquid water returns to the phase change boiler body 3, and the separated water vapor 6 is sent to the phase change heat exchanger 7 through a main steam valve 5 to heat the gaseous organic working medium 17 out of the economizer 16, and the produced condensed water 8 directly or after being pressurized by a circulating water pump 9 returns to the phase change boiler body 3,

[0018] The gaseous organic working medium 17 out of the economizer 16 is heated by the water vapor 6 in the phase change heat exchanger 7 to form a superheated organic working medium 12, which enters the organic working medium gas turbine 13 to drive an organic working medium generator 18 to generate power, or to drive operating equipment such as a water pump, a ship propeller, etc., the organic working medium generator 18 is equivalent to an organic working medium doer, the exhaust steam out of the organic working medium gas turbine 13 is condensed by the organic working medium condenser 14 to form liquid organic working medium, and the liquid organic working medium is sent to the economizer 16 by the organic working medium circulating pump 15, thereby forming a circulation process of the organic working medium in the organic Rankine cycle power generation unit,

[0019] The waste heat source 2 is cooled by the phase change boiler body 3 and the economizer 16, and then transported to subsequent equipment (such as the next production process, a dust remover, a desulfurization or denitrification equipment, etc.) for treatment, to obtain corresponding products or be discharged as three wastes.

[0020] The phase change boiler body 3 comprises the steam-water separator 4, which is only marked as a separate component to highlight the steam-water separation function of the steam-water separator 4.

[0021] The waste heat source 2 includes one or more of gaseous, liquid or solid state, such as 202520172730.3-high temperature magnesium slag sensible heat waste heat recovery device, 202310573665.0- sensible heat waste heat recovery device and method of molten calcium carbide, 202122078113.1 dry quenching flue gas waste heat boiler tail exhaust flue gas economizer equipment, 201911143005.9-cement clinker cooling system and method, etc., which provides a waste heat recovery device and method for recovering gaseous, solid and liquid waste heat sources.

[0022] The economizer 16 adopts a heat exchange mode of partition wall, and adopts heat transfer enhancement measures such as finned tube, spiral groove tube, internally threaded tube, etc.

[0023] The phase change heat exchanger 7 adopts a heat exchange mode of partition wall, preferably, the phase change heat exchanger 7 adopts a shell-and-tube heat exchanger, the water vapor output by the phase change boiler body 3 goes to the shell side, and the gaseous organic working medium 17 goes to the tube side; a safety valve is arranged on the low-pressure side of the phase change heat exchanger 7 to prevent the medium on the higher-pressure side from leaking into the low-pressure side due to the heat exchange surface, thereby causing overpressure.

[0024] The phase change boiler body 3 includes a convection heat exchange tube, a steam-water separator 4 and a header, the steam-water separator 4 and the header can be integrated, and the internal circulating steam boiler is designed according to the principle of natural circulation or forced circulation.

[0025] Preferably, the phase change boiler body 3 adopts heat transfer enhancement technology, such as internally threaded tube, spiral groove tube, membrane wall, etc.

[0026] A water supplementing line is arranged: desalted water or purified water is supplemented into the water circulation loop of the internal circulating steam boiler by a booster water pump, for supplementing the steam-water loss generated by the internal circulating steam boiler. The desalted water or purified water is prepared by a water treatment device; the water treatment device removes harmful components such as calcium and magnesium ions in the water by using ultrafiltration reverse osmosis membrane and cation and anion exchange resin, and removes dissolved oxygen therein by using a normal-temperature or thermal deaerator.

[0027] A safety valve is arranged on the steam space leading-out safety valve connection pipe of the steam-water separator 4 to prevent overpressure operation of the phase change boiler body 3.

[0028] Because the internal circulating steam boiler adopts a closed water circulation loop, the steam-water loss is extremely small, and the purified water is used to supplement the steam-water loss, so the dissolved oxygen in the purified water is extremely small, and compared with the traditional open circulating steam boiler, the cumulative effect of scale formation and oxygen corrosion of the internal circulating steam boiler is basically eliminated.

[0029] The organic working fluid condenser 14 employs conventional air cooling or water cooling processes. Preferably, the organic working fluid condenser 14 uses a closed-loop circulating water cooling process, where the heated cooling water exiting the organic working fluid condenser 14 is cooled by the cooling tower 21 and then pumped back into the organic working fluid condenser 14 by the cooling water pump 22, thus forming a closed-loop circulation process for the cooling water. The cooling tower 21 is equipped with a fan 25 and a water distributor 20 to enhance heat and mass transfer.

[0030] The cooling water system of the organic working fluid condenser 14 adopts an open circulation process or a closed circulation process.

[0031] A condenser-evaporator 11 is provided: the liquid organic working fluid from the organic working fluid circulation pump 15 is divided into two paths, which are heated by the economizer 16 and the condenser-evaporator 11 respectively to produce gaseous organic working fluid. The gaseous organic working fluid is then sent to the phase change heat exchanger 7. The water vapor drawn from the steam-water separator 4 is cooled by the condenser-evaporator 11 to form condensate, which is then returned to the water circulation loop of the internal circulation steam boiler.

[0032] The condenser-evaporator 11 adopts a shell-and-tube heat exchange method. Preferably, the condenser-evaporator 11 adopts a shell-and-tube heat exchanger, wherein water vapor flows through the shell side and organic working fluid flows through the tube side.

[0033] The organic working fluid of the organic Rankine cycle generator set in this disclosure is a single-component organic working fluid or a multi-component organic working fluid, such as a cascade ORC generator set or a mixed working fluid ORC generator set. Among the multi-component organic working fluids, the organic working fluid that has been circulated by the organic Rankine cycle generator set is the basic circulating working fluid.

[0034] When the organic working fluid generator 18 in this disclosure is replaced with an organic working fluid power generator to directly drive operating equipment such as a ship propeller, the organic Rankine cycle power generation system becomes an organic Rankine cycle power generation system.

[0035] For the parts not mentioned in this disclosure, existing steam boilers and organic Rankine cycle power generation technology can be used. That is, existing, well-known, mature and reliable reasonable technical measures can be introduced into this system, such as setting up necessary valves, pressure gauges, temperature control instruments, water level gauges, alarm instruments, bypasses, automatic control facilities, etc.

[0036] The present invention has the following advantages over the prior art:

[0037] 1. This invention expands the application field of ORC (Organic Recycled Gas) from the traditional low-temperature range (80℃~250℃) of waste heat recovery to the medium-high temperature range (300℃~500℃). Specifically, it utilizes an internal circulation steam boiler to recover heat in the medium-high temperature range for ORC power generation. The high efficiency of ORC in the low-temperature range compensates for the efficiency losses of the steam Rankine cycle in the medium-high temperature range (the output power of an ORC turbine in the low-temperature range can reach more than twice that of the steam Rankine cycle). While retaining the advantages of water as a working medium for waste heat recovery, it fully leverages the advantages of ORC, enabling its application in various fields. Waste heat recovery from gas turbines can transform existing gas-steam combined cycle power generation technology or gas-ORC combined cycle power generation technology into a new gas-steam-organic working fluid combined cycle power generation system. This is equivalent to eliminating the bulky steam turbine generator set, condenser, water treatment equipment (including deaerator), and superheater in the steam Rankine cycle, while retaining the boiler evaporation heating surface and economizer. The system is replaced with an ORC unit that is more compact in terms of equipment and space and has simplified auxiliary equipment. This results in lower investment and simpler and more convenient operation and management. This disclosure is also applicable to the replacement and upgrading of existing ship steam power systems.

[0038] 2. The internal circulation steam boiler adopts a closed-loop clean water circulation process, unlike the open circulation process in traditional power plant boilers or waste heat boilers, which requires continuous water replenishment to compensate for steam and water losses caused by continuous blowdown, turbine steam leakage, and deaeration by the deaerator. The internal circulation steam boiler's heating surfaces are free from scale formation and oxygen corrosion accumulation, thus avoiding the possibility of scale and oxygen corrosion on the convective heat exchange surfaces and the steam condensation side heat exchange surfaces of the phase change heat exchanger. While retaining the advantage of the high heat absorption capacity of the working fluid (water) in the phase change boiler, it eliminates the harm caused by poor water quality to the internal circulation steam boiler, preserving the advantages of organic Rankine cycle turbine power generation. The unit has the advantage of not requiring supporting water treatment equipment. Only a very small capacity water treatment device is needed to meet the emergency water demand of the internal circulation steam boiler. The investment, management and operating costs of water treatment equipment are greatly reduced. The phase change heat exchanger operates in the medium temperature range below the critical temperature of water, thus avoiding the risk of material overheating and burning. This greatly reduces the regulatory risks of national regulatory authorities, as well as the safety risks of users and operators. It also brings economic benefits from long-term operation of the equipment and a significant reduction in related costs due to convenient maintenance and repair. This ensures the safe, economical and long-term operation of the organic Rankine cycle power generation system.

[0039] 3. The phase change boiler body, phase change heat exchanger, economizer, condenser-evaporator and organic working fluid condenser in this disclosure are all heat exchange devices that undergo phase change, with high heat transfer efficiency. The waste heat source is compactly and efficiently cooled through the phase change heat absorption of the phase change boiler body and economizer. The organic working fluid efficiently completes the organic Rankine cycle power generation process through the phase change heat exchanger, economizer, condenser-evaporator and organic working fluid condenser. Compared with the existing steam Rankine cycle power generation and organic Rankine cycle power generation technologies, the system is significantly optimized.

[0040] 4. The internal circulation steam boiler adopts a closed-loop circulation method. If a circulating water pump is set up for limited forced circulation, the circulating water pump does not need to be a multi-stage pump. Only the pressure resistance, temperature resistance and overcoming friction resistance need to be considered, and the power consumption is very small.

[0041] 5. The scale-free and oxygen-free circulation process of the internal circulation steam boiler provides a variety of possibilities for the optimized design of the boiler's heating surface, such as adopting once-through boiler technology with a high circulation ratio, and using internal threads, internal and external spiral groove tubes, and other heat transfer enhancement measures for water-cooled wall tubes or convection heat exchange tubes.

[0042] 6. Utilizing the advantages of the working fluid in the phase change boiler (water absorbs a large amount of heat in the evaporation section), most of the heat absorption (used for the evaporation of the liquid organic working fluid) that would otherwise be completed in the preheating evaporation section (i.e., the economizer within the waste heat source channel) in traditional organic Rankine cycle units is transferred to a condenser-evaporator located outside the boiler as a heat transfer medium for consumption. This condenser-evaporator is essentially a preheating evaporation section for the organic working fluid located outside the waste heat source channel (i.e., an economizer outside the waste heat source channel). Compared to traditional organic Rankine cycle units... The organic working fluid preheating evaporator and organic working fluid superheater arranged in the waste heat source channel of the unit are replaced by a condensing evaporator and phase change heat exchanger outside the waste heat source channel in this invention. This greatly reduces the heat exchange area of ​​the organic working fluid heat exchanger arranged in the waste heat source channel (reduces the heat exchange area of ​​the economizer in the waste heat source channel and eliminates the organic working fluid superheater in the waste heat source channel). The safety of the organic working fluid preheating evaporation section in the waste heat source channel and the safety of the entire organic Rankine cycle unit are greatly enhanced.

[0043] 7. ORC units have strong adaptability to load changes and adopt sliding pressure operation mode. They can still maintain high efficiency under partial load and the system thermal balance is easier to organize, which has advantages that steam Rankine cycle generator sets cannot match.

[0044] 8. This disclosed solution is suitable for waste heat recovery in continuous, long-cycle operation projects. It is applicable to both newly constructed waste heat recovery projects and energy-saving retrofits of existing waste heat boiler steam heating plants. It should be noted that when retrofitting existing waste heat boiler steam heating plants for energy conservation, the pressure-bearing capacity of the economizer needs to be recalculated and verified through a hydrostatic test to ensure that its pressure-bearing capacity meets the pressure requirements of organic Rankine cycle units. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the process flow of the organic Rankine cycle power generation system using a phase change heat exchanger according to the present invention.

[0046] Figure 1 In the middle section, 2-waste heat source, 3-phase change boiler body, 4-steam-water separator, 5-main steam valve, 6-steam, 7-phase change heat exchanger, 8-condensate, 9-condensate pump, 10-heat source channel, 11-condenser-evaporator, 12-superheated organic working fluid, 13-organic working fluid turbine, 14-organic working fluid condenser, 15-organic working fluid circulating pump, 16-economizer, 17-gaseous organic working fluid, 18-organic working fluid generator, 19-low temperature waste heat source, 20-water equalizer, 21-cooling tower, 22-cooling water pump, 23-condenser inlet, 24-condenser outlet, 25-fan. Detailed Implementation

[0047] The present disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Example 1:

[0049] As attached Figure 1 As shown, an organic Rankine cycle power generation system employing a phase change heat exchanger is described. The organic Rankine cycle power generation system includes an internal circulation steam boiler and an organic Rankine cycle generator set. The internal circulation steam boiler includes a phase change boiler body 3, a steam-water separator 4, and a phase change heat exchanger 7. The organic Rankine cycle generator set includes an organic working fluid circulation pump 15, an economizer 16, the phase change heat exchanger 7, an organic working fluid turbine 13, an organic working fluid condenser 14, and connecting pipes. The internal circulation steam boiler and the organic Rankine cycle generator set form the organic Rankine cycle power generation system through the phase change heat exchanger 7.

[0050] The steam-water mixture generated by the contact between the phase change boiler body 3 and the waste heat source 2 enters the steam-water separator 4, where steam and water are separated. The separated liquid water returns to the phase change boiler body 3, and the separated steam 6 is sent to the phase change heat exchanger 7 via the main steam valve 5 to heat the gaseous organic working fluid 17 from the economizer 16. The resulting condensate 8 is pressurized by the circulating water pump 9 and then returns to the phase change boiler body 3.

[0051] The gaseous organic working fluid 17 exiting the economizer 16 is heated by steam 6 in the phase change heat exchanger 7 to form superheated organic working fluid 12, which then enters the organic working fluid turbine 13 to drive the organic working fluid generator 18 to generate electricity. The exhaust steam from the organic working fluid turbine 13 is condensed in the organic working fluid condenser 14 to form liquid organic working fluid, which is then sent back to the economizer 16 via the organic working fluid circulation pump 15, thus forming a circulation process of the organic working fluid in the organic Rankine cycle generator set.

[0052] The waste heat source 2 is high-temperature flue gas. After being cooled by the phase change boiler body 3 and economizer 16, the waste heat source 2 forms low-temperature flue gas, i.e., low-temperature heat source 19. It is then transported to subsequent equipment (such as dust collector, desulfurization or denitrification equipment, etc.) for treatment, and then discharged through induced draft fan and chimney.

[0053] The phase change boiler body 3 and the steam-water separator 4 are an integrated structure, and are listed as separate components only to highlight the steam-water separation function of the steam-water separator 4.

[0054] The economizer 16 adopts a partitioned heat exchange method and employs enhanced heat transfer measures such as finned tubes, spiral grooved tubes, and internally threaded tubes.

[0055] The phase change heat exchanger 7 adopts a shell-and-tube heat exchange method. Preferably, the phase change heat exchanger 7 adopts a shell-and-tube heat exchanger, with the steam output from the phase change boiler body 3 flowing through the shell side and the gaseous organic working fluid 17 flowing through the tube side. A safety valve is installed on the low-pressure side of the phase change heat exchanger 7 to prevent the medium on the higher pressure side from leaking into the low-pressure side due to heat exchange surface leakage, which could lead to overpressure.

[0056] The phase change boiler body 3 includes a convection heat exchange tube, a steam-water separator 4, and a header. The steam-water separator 4 and the header can be integrated. The internal circulation steam boiler is designed according to the principle of natural circulation or forced circulation.

[0057] Preferably, the phase change boiler body 3 adopts enhanced heat transfer technology, such as internally threaded pipes, spiral grooved pipes, membrane walls, etc.

[0058] A water replenishment line is provided: demineralized water or purified water is pumped into the water circulation loop of the internal circulation steam boiler to compensate for the steam and water losses generated by the internal circulation steam boiler. The demineralized water or purified water is produced by water treatment equipment; the water treatment equipment uses ultrafiltration reverse osmosis membranes, anion and cation exchange resins, etc., to remove calcium and magnesium ions from the water, and then uses a thermal deaerator to remove dissolved oxygen.

[0059] The steam space of the steam-water separator 4 has a safety valve connection pipe and two safety valves to prevent the phase change boiler body 3 from operating under overpressure.

[0060] The organic working fluid condenser 14 employs a water cooling process. Preferably, the organic working fluid condenser 14 uses an open-loop cooling tower process, where the heated cooling water exiting the organic working fluid condenser 14 is cooled by the cooling tower 21 and then pumped back into the organic working fluid condenser 14 by the cooling water pump 22, thus forming a closed-loop circulation process for the cooling water. The cooling tower 21 is equipped with a fan 25 and a water distributor 20 to enhance heat and mass transfer.

[0061] A condenser-evaporator 11 is provided: the liquid organic working fluid from the organic working fluid circulation pump 15 is divided into two paths, which are heated by the economizer 16 and the condenser-evaporator 11 respectively to produce gaseous organic working fluid. The gaseous organic working fluid is then combined and sent to the phase change heat exchanger 7. The water vapor drawn from the steam-water separator 4 is cooled by the condenser-evaporator 11 to form condensate, which enters the inlet pipeline of the circulating water pump 9. The condenser-evaporator 11 is a shell-and-tube heat exchanger, in which water vapor flows through the shell side and the organic working fluid flows through the tube side.

[0062] The organic working fluid used in the organic Rankine cycle generator set disclosed herein is a single-component organic working fluid, such as R245fa.

[0063] For the parts not mentioned in this disclosure, existing waste heat boilers and organic Rankine cycle power generation technology can be used. That is, existing, well-known, mature and reliable reasonable technical measures can be introduced into this system, such as setting up necessary valves, pressure gauges, safety valves, temperature control instruments, water level gauges, alarm instruments, bypasses, automatic control facilities, etc.

[0064] Although the present invention has been disclosed above with reference to preferred embodiments, these are not intended to limit the invention. Any person skilled in the art can make various changes or modifications without departing from the spirit and scope of this disclosure, and these changes also fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims of this application.

Claims

1. An organic Rankine cycle power generation system employing a phase change heat exchanger, characterized in that: The organic Rankine cycle power generation system includes an internal circulation steam boiler and an organic Rankine cycle generator set. The internal circulation steam boiler includes a phase change boiler body (3) and a phase change heat exchanger (7). The organic Rankine cycle generator set includes an organic working fluid circulation pump (15), an economizer (16), a phase change heat exchanger (7), an organic working fluid turbine (13), an organic working fluid condenser (14), and connecting pipes. The internal circulation steam boiler and the organic Rankine cycle generator set form an organic Rankine cycle power generation system through the phase change heat exchanger (7). The steam generated by the phase change boiler body (3) in contact with the waste heat source (2) is sent to the phase change heat exchanger (7) to heat the gaseous organic working fluid coming out of the economizer (16). The condensate generated is returned to the phase change boiler body (3) directly or after being pressurized by the circulating water pump (9). The gaseous organic working fluid generated by the economizer (16) is heated by steam in the phase change heat exchanger (7) to form a superheated organic working fluid (12), which then enters the organic working fluid turbine (13) to drive the organic working fluid generator (18) to generate electricity. The exhaust steam from the organic working fluid turbine (13) is condensed in the organic working fluid condenser (14) to form a liquid organic working fluid, which is then sent to the economizer (16) for heating via the organic working fluid circulation pump (15), thus forming the circulation process of the organic working fluid in the organic Rankine cycle generator set. The waste heat source (2) is cooled by the phase change boiler body (3) and economizer (16) and then transported to subsequent equipment to obtain corresponding products or discharged as waste.

2. The organic Rankine cycle power generation system according to claim 1, characterized in that: The waste heat source (2) can be in one or more states, including gaseous, liquid or solid.

3. The organic Rankine cycle power generation system according to claim 1, characterized in that: The internal circulation steam boiler adopts the principle of natural circulation or forced circulation.

4. The organic Rankine cycle power generation system according to claim 1, characterized in that: A water supply line is provided: demineralized water or purified water is supplied to the water circulation loop of the internal circulation steam boiler via a booster pump.

5. The organic Rankine cycle power generation system according to claim 1, characterized in that: A condenser evaporator (11) is provided: the liquid organic working fluid from the organic working fluid circulation pump (15) is divided into two paths, which are respectively passed through the economizer (16) and the condenser evaporator (11) to absorb heat and generate gaseous organic working fluid. The gaseous organic working fluid is then sent to the phase change heat exchanger (7). The steam drawn from the internal circulation steam boiler is cooled by the condenser evaporator (11), and the resulting condensate is returned to the water circulation loop of the internal circulation steam boiler.

6. The organic Rankine cycle power generation system according to claim 1, characterized in that: The phase change heat exchanger (7) adopts a wall-type heat exchange method.

7. The organic Rankine cycle power generation system according to claim 6, characterized in that: The phase change heat exchanger (7) adopts a shell-and-tube heat exchanger, in which steam flows through the shell side and organic working fluid flows through the tube side.

8. The organic Rankine cycle power generation system according to claim 1, characterized in that: The organic working medium in the organic Rankine cycle generator set is a single-component organic working medium or a multi-component organic working medium.

9. The organic Rankine cycle power generation system according to claim 1, characterized in that: The cooling water of the organic working fluid condenser (14) adopts an open circulation process or a closed circulation process.

10. The organic Rankine cycle power generation system according to claim 1, characterized in that: The organic working fluid turbine (13) drives the organic working fluid power generator to drive the operating equipment, and the organic Rankine cycle power generation system becomes an organic Rankine cycle power generation system.

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