High-pressure condensed water comprehensive power generation system and working method thereof

Abstract

According to the high-pressure condensed water comprehensive power generation system and the working method thereof, steam expansion power generation and ORC power generation are coupled, and high-pressure condensed water energy is recycled to the maximum extent. The steam expansion machine and the organic working medium expansion machine are coaxially connected with the generator; an outlet of the organic working medium condenser is connected with a cold-phase inlet of a heat exchanger III, a cold-phase outlet of the heat exchanger III is connected with a cold-phase inlet of a heat exchanger II, a cold-phase outlet of the heat exchanger II is connected with a cold-phase inlet of a heat exchanger I, and a cold-phase outlet of the heat exchanger I is connected with a working medium inlet of an organic working medium expansion machine; a dead steam outlet of the steam expansion machine is connected with a hot phase inlet of the heat exchanger I, and a hot phase outlet of the heat exchanger I is connected with a steam inlet of the water jet steam extractor; a flash evaporation condensation water outlet of the flash evaporation tank is connected with a hot phase inlet of the second heat exchanger, a hot phase outlet of the second heat exchanger is connected with a water inlet of the water jet steam extractor, and a water outlet of the water jet steam extractor is connected with a hot phase inlet of the third heat exchanger.

Description

Technical Field

[0001] The invention relates to a high-pressure condensate integrated power generation system and a working method thereof, which are mainly used for recycling high-pressure condensate of a high-pressure heater. Background Art

[0002] High-parameter high-pressure heaters are often used in chemical fiber, refining, metal smelting and other industries. Taking chemical fiber polyester process heater as an example, the working pressure is usually around 12MPa. The high-pressure condensate of the high-pressure heater has the characteristics of high temperature, high pressure, high energy content and high danger. Whether the high-pressure condensate can be reasonably used is closely related to the energy utilization rate, production economy and production safety of the enterprise. Therefore, the design and use of high-pressure condensate recovery and utilization equipment is very important. At present, there are usually the following treatment methods: (1) Direct flash evaporation of high-pressure condensate. The steam and condensate parameters and operating risks after flash evaporation are greatly reduced, and can be reused or discharged according to demand. This method has high operating reliability, but it is necessary to find a channel for absorbing the working fluid after flash evaporation, otherwise there will be a large waste of energy.

[0003] (2) After the high-pressure condensate is pressurized, it is directly returned to the boiler (the source of the high-pressure heating steam). In theory, this method can completely reuse the energy of the high-pressure condensate. However, in actual application, it is often impossible to implement or the implementation effect is poor because the high-pressure heater is far away from the boiler, the pressure drop during the condensate transportation process is large and cavitation is easy to occur, the investment cost of long-distance transportation is high, the high-pressure parameter condensate booster pump is difficult to select, and the operation failure rate is high.

[0004] (3) High-pressure condensate is directly flashed, and the steam after flashing is used to generate electricity through a steam expander. The condensate after flashing can be used to recover the heat of water through an organic Rankine cycle (ORC). In actual applications, these two waste heat power generation systems are usually independent, and there are the following problems: (a) ORC has a small temperature rise and a small power generation capacity.

[0005] (b) The exhaust steam from steam expansion power generation cannot be absorbed and needs to be cooled with circulating water, which increases the power consumption of auxiliary equipment and the loss of cold source, resulting in low thermal efficiency of the unit.

[0006] (c) Two sets of system equipment require a large floor space and high construction investment. Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a high-pressure condensate integrated power generation system with a reasonable structural design and a working method thereof, which couples steam expansion power generation and ORC power generation to maximize the recovery of high-pressure condensate energy.

[0008] The technical solution adopted by the present invention to solve the above-mentioned problems is: a high-pressure condensate integrated power generation system, including a flash tank, a steam expander, an organic working fluid expander, an organic working fluid condenser and a generator; the working fluid outlet of the organic working fluid expander is connected to the inlet of the organic working fluid condenser; the flash steam outlet of the flash tank is connected to the steam inlet of the steam expander; it is characterized in that it also includes a heat exchanger 1, a heat exchanger 2, a heat exchanger 3 and a water jet steam extractor; the steam expander and the organic working fluid expander are coaxially connected to the generator; the outlet of the organic working fluid condenser is connected to the cold inlet of the heat exchanger 3 The cold phase outlet of heat exchanger three is connected with the cold phase inlet of heat exchanger two, the cold phase outlet of heat exchanger two is connected with the cold phase inlet of heat exchanger one, and the cold phase outlet of heat exchanger one is connected with the working fluid inlet of the organic working fluid expander; the exhaust steam outlet of the steam expander is connected with the hot phase inlet of heat exchanger one, and the hot phase outlet of heat exchanger one is connected with the steam inlet of the water jet steam extractor; the flash condensate outlet of the flash tank is connected with the hot phase inlet of heat exchanger two, the hot phase outlet of heat exchanger two is connected with the water inlet of the water jet steam extractor, and the water outlet of the water jet steam extractor is connected with the hot phase inlet of heat exchanger three.

[0009] The present invention also includes an organic working medium circulation pump, and the outlet of the organic working medium circulation pump of the organic working medium condenser is connected to the cold phase inlet of the heat exchanger three.

[0010] The present invention also includes a booster water pump, and the hot phase outlet of the second heat exchanger is connected to the water inlet of the water jet steam extractor through the booster water pump.

[0011] The booster water pumps described in the present invention are multiple and are arranged in series or in parallel.

[0012] A working method of a high-pressure condensate integrated power generation system, characterized in that it comprises the following steps: 1) Steam cycle power generation process; The high-pressure condensate of the high-pressure heater enters the flash tank for flash evaporation, generating flash steam and flash condensate; the flash steam enters the steam expander to drive the expander to do work, driving the generator to generate electricity, and the exhaust steam generated by the steam expander enters the heat exchanger for heat exchange, and then enters the water jet steam extractor; 2) Steam exhaust absorption process; The flash condensed water from the flash tank enters the second heat exchanger, and the organic working fluid absorbs the heat of the flash condensed water through the second heat exchanger to reduce the temperature of the flash condensed water; the flash condensed water then enters the water jet steam extractor; the mixed water from the water jet steam extractor enters the third heat exchanger for heat exchange, transferring the heat of the mixed water to the organic working fluid; 3) ORC cycle power generation process; The organic working fluid of the organic working fluid expander first enters the organic working fluid condenser for cooling, and then passes through heat exchanger three, heat exchanger two, and heat exchanger one in sequence to heat and vaporize the organic working fluid, and then returns to the organic working fluid expander to drive the expander to do work, thereby driving the generator to generate electricity; the expanded organic working fluid is cooled by the organic working fluid condenser, and then returns to the heat exchanger three, completing the cycle of power generation.

[0013] In step 2) of the present invention, the mixed water from the water ejector is converted into low-temperature water after heat exchange in the third heat exchanger, and is discharged from the hot phase outlet of the third heat exchanger for external transmission.

[0014] Compared with the prior art, the present invention has the following advantages and effects: 1. In the conventional system, the flash steam and the flash condensed water after the flash evaporation of the high-pressure condensed water generate electricity separately, which are two sets of power generation systems. However, the present invention creatively uses the principle of water jet steam extraction to combine the two working fluids into one.

[0015] 2. Use the three-stage heat exchanger to fully utilize the heat in each temperature range from low to high, thereby improving the thermal efficiency of the unit.

[0016] 3. The flash condensate, steam expander exhaust steam and the mixed medium of the two are heat exchanged in stages to fully absorb the heat of each temperature section and heat the temperature of the organic working fluid to a higher value, which not only consumes the steam expander exhaust steam but also increases the ORC power generation.

[0017] 4. The ORC cycle expander and steam expander are coaxially arranged to generate electricity together, which further improves the system integration and provides technical support for the skid-mounted design of the device and reduces investment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0020] The embodiment of the present invention includes a flash tank 1, a steam expander 2, a generator 3, a heat exchanger 1 4, a water jet steam extractor 5, a booster pump 6, a heat exchanger 2 7, an organic working fluid expander 8, an organic working fluid condenser 9, an organic working fluid circulation pump 10, a heat exchanger 3 11, a pipeline 1 12, a pipeline 2 13, a pipeline 3 14, a pipeline 4 15, a pipeline 5 16, a pipeline 6 17 and a pipeline 7 18.

[0021] The steam expander 2 and the organic working fluid expander 8 are coaxially connected with the generator 3, and jointly drive the generator 3. This solution couples steam power generation and ORC power generation together, realizes system integration, reduces floor space and investment, and facilitates skid-mounted design of system devices.

[0022] The working fluid outlet of the organic working fluid expander 8 is connected to the inlet of the organic working fluid condenser 9, the outlet of the organic working fluid condenser 9 is connected to the cold phase inlet of the heat exchanger three 11 through the pipeline five 16 and the organic working fluid circulation pump 10, the cold phase outlet of the heat exchanger three 11 is connected to the cold phase inlet of the heat exchanger two 7, the cold phase outlet of the heat exchanger two 7 is connected to the cold phase inlet of the heat exchanger one 4, and the cold phase outlet of the heat exchanger one 4 is connected to the working fluid inlet of the organic working fluid expander 8 through the pipeline six 17.

[0023] The flash steam outlet of the flash tank 1 is connected to the steam inlet of the steam expander 2 through the pipeline 12, the exhaust steam outlet of the steam expander 2 is connected to the hot phase inlet of the heat exchanger 4 through the pipeline 2 13, and the hot phase outlet of the heat exchanger 4 is connected to the steam inlet of the water jet steam extractor 5 through the pipeline 7 18; The flash condensate outlet of the flash tank 1 is connected to the hot phase inlet of the heat exchanger 2 7 through the pipeline 3 14, and the hot phase outlet of the heat exchanger 2 7 is connected to the water inlet of the water ejector 5 through the booster pump 6 and the pipeline 4 15; the water outlet of the water ejector 5 is connected to the hot phase inlet of the heat exchanger 3 11. There are multiple booster pumps 6, which are arranged in series or in parallel.

[0024] A working method of a high-pressure condensate integrated power generation system comprises the following steps: 1) Steam cycle power generation process; The high-pressure condensate of the high-pressure heater enters the flash tank 1 for flash evaporation, generating flash steam and flash condensate. The flash steam enters the steam expander 2 through the pipeline 12 to drive the expander to do work, driving the generator 3 to generate electricity, and the exhaust steam enters the heat exchanger 1 4 through the pipeline 2 13, and then enters the water jet steam extractor 5 through the pipeline 7 18.

[0025] 2) Steam exhaust absorption process; The flash condensed water of the flash tank 1 enters the heat exchanger 2 7 through the pipeline 3 14, and then is pressurized by the booster pump 6. In this process, the organic working fluid absorbs the heat of the flash condensed water through the heat exchanger 2 7, lowering the water temperature of the condensed water, so that the inlet of the booster pump 6 is not prone to cavitation; After the booster pump 6 is pressurized, the flash condensed water enters the water jet steam extractor 5 through the pipeline 15, and absorbs the exhaust steam of the steam expander 2 through the water jet steam extraction principle, thereby realizing the unified combination of the working medium discharge of the flash system; The mixed water from the water jet extraction device 5 enters the heat exchanger three 11 for heat exchange, and the heat of the mixed water is transferred to the organic working fluid. The working fluid in the pipeline seven 18 can be gaseous, liquid, or gas-liquid two-phase. This process remixes the working fluids of flash steam and flash condensed water, realizing the unified discharge of the flash system. At the same time, this process replaces the traditional steam condenser through the combination of organic working fluid heat absorption (heat exchanger one 4) and absorption heat exchange (water jet extraction device 5 mixing), saving a large amount of circulating cooling water; The mixed water coming out of the water jet steam extractor 5 is converted into low-temperature water after heat exchange in the heat exchanger three 11, and is discharged from the hot phase outlet of the heat exchanger three 11 for external transmission.

[0026] 3) ORC cycle power generation process; The organic working fluid of the organic working fluid expander 8 first enters the organic working fluid condenser 9 for cooling, and then is pressurized by the organic working fluid circulation pump 10, and then passes through the heat exchanger three 11, the heat exchanger two 7, and the heat exchanger one 4 in sequence to heat and vaporize the organic working fluid, and then returns to the organic working fluid expander 8 through the pipeline six 17 to drive the expander to do work, and drive the generator 3 to generate electricity. The expanded organic working fluid is cooled by the organic working fluid condenser 9, and then returns to the heat exchanger three 11 through the pipeline five 16 and the organic working fluid circulation pump 10, completing the cycle power generation. This process conducts step-by-step heat exchange of flash condensed water, steam expander 2 exhaust steam, and the mixed medium of the two, fully absorbs the heat of each temperature section, heats the temperature of the organic working fluid to a higher value, and improves the ORC power generation.

[0027] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A high-pressure condensate integrated power generation system, comprising a flash tank, a steam expander, an organic working fluid expander, an organic working fluid condenser and a generator; the working fluid outlet of the organic working fluid expander is connected to the inlet of the organic working fluid condenser; the flash steam outlet of the flash tank is connected to the steam inlet of the steam expander; characterized in that: It also includes heat exchanger one, heat exchanger two, heat exchanger three and a water jet extraction device; the steam expander and the organic working fluid expander are coaxially connected to the generator; the outlet of the organic working fluid condenser is connected to the cold phase inlet of heat exchanger three, the cold phase outlet of heat exchanger three is connected to the cold phase inlet of heat exchanger two, the cold phase outlet of heat exchanger two is connected to the cold phase inlet of heat exchanger one, and the cold phase outlet of heat exchanger one is connected to the working fluid inlet of the organic working fluid expander; the exhaust steam outlet of the steam expander is connected to the hot phase inlet of heat exchanger one, and the hot phase outlet of heat exchanger one is connected to the steam inlet of the water jet extraction device; the flash condensate outlet of the flash tank is connected to the hot phase inlet of heat exchanger two, the hot phase outlet of heat exchanger two is connected to the water inlet of the water jet extraction device, and the water outlet of the water jet extraction device is connected to the hot phase inlet of heat exchanger three.

2. The high-pressure condensate integrated power generation system according to claim 1 is characterized in that: It also includes an organic working medium circulation pump, and the outlet of the organic working medium circulation pump of the organic working medium condenser is connected to the cold phase inlet of the heat exchanger three.

3. The high-pressure condensate integrated power generation system according to claim 1 is characterized in that: It also includes a booster water pump, and the hot phase outlet of the second heat exchanger is connected to the water inlet of the water jet steam extractor through the booster water pump.

4. The high-pressure condensate integrated power generation system according to claim 1 is characterized in that: The booster water pumps are multiple and are arranged in series or in parallel.

5. A working method of the high-pressure condensate integrated power generation system according to any one of claims 1 to 4, characterized in that: The steps include: 1) Steam cycle power generation process; The high-pressure condensate of the high-pressure heater enters the flash tank for flash evaporation, generating flash steam and flash condensate; the flash steam enters the steam expander to drive the expander to do work, driving the generator to generate electricity, and the exhaust steam generated by the steam expander enters the heat exchanger for heat exchange, and then enters the water jet steam extractor; 2) Steam exhaust absorption process; The flash condensed water from the flash tank enters the second heat exchanger, and the organic working fluid absorbs the heat of the flash condensed water through the second heat exchanger to reduce the temperature of the flash condensed water; the flash condensed water then enters the water jet steam extractor; the mixed water from the water jet steam extractor enters the third heat exchanger for heat exchange, transferring the heat of the mixed water to the organic working fluid; 3) ORC cycle power generation process; The organic working fluid of the organic working fluid expander first enters the organic working fluid condenser for cooling, and then passes through heat exchanger three, heat exchanger two, and heat exchanger one in sequence to heat and vaporize the organic working fluid, and then returns to the organic working fluid expander to drive the expander to do work, thereby driving the generator to generate electricity; the expanded organic working fluid is cooled by the organic working fluid condenser, and then returns to the heat exchanger three, completing the cycle of power generation.

6. The working method according to claim 5, characterized in that: In step 2), the mixed water from the water jet steam extractor is converted into low-temperature water after heat exchange in the heat exchanger 3, and is discharged from the hot phase outlet of the heat exchanger 3 for external transmission.

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