CN115653706A - A steam turbine waste heat utilization system and its control method - Google Patents

Abstract

The invention discloses a steam turbine waste heat utilization system which comprises a steam ejector, wherein an air inlet of the steam ejector is connected with an exhaust pipe of a low-pressure cylinder of a steam turbine, the steam ejector is connected with a low-temperature water inlet pipe and a high-temperature water outlet pipe, low-temperature water in the low-temperature water inlet pipe absorbs heat in the steam ejector and is changed into high-temperature water and then is discharged from the high-temperature water outlet pipe, an air outlet of the steam ejector is connected with a low-temperature heat source inlet of a heat absorption heat pump, a condensed water drain pipe of the heat absorption heat pump is connected with the low-temperature water inlet pipe, the exhaust pipe of the low-pressure cylinder of the steam turbine is connected with the high-temperature heat source inlet of the heat absorption heat pump, the heat absorption heat pump is connected with the low-temperature water inlet pipe and a medium-temperature water outlet pipe, and low-temperature water in the low-temperature water inlet pipe absorbs heat in the heat absorption heat pump and is changed into medium-temperature water and then is discharged from the medium-temperature water outlet pipe. The invention can improve the defects of the prior art and improve the waste heat utilization rate of the steam turbine unit of the thermal power plant.

Description

A steam turbine waste heat utilization system and its control method

technical field

The invention relates to the technical field of steam turbine waste heat recovery and utilization, in particular to a steam turbine waste heat utilization system and a control method thereof.

Background technique

After the steam turbine in the thermal power plant works to drive the generator to start, a large amount of high-temperature exhaust steam will be generated. In order to improve the overall efficiency of coal-fired units, secondary recovery and utilization of waste heat from high-temperature exhaust steam is required. In the existing waste heat recovery system, waste heat recovery of high temperature waste steam is usually realized through heat exchange between high temperature waste steam and low temperature water, but the recovery rate is only 30%-40%.

Contents of the invention

The technical problem to be solved by the present invention is to provide a steam turbine waste heat utilization system and its control method, which can solve the deficiencies of the prior art and improve the waste heat utilization rate of the steam turbine unit in a thermal power plant.

In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

A steam turbine waste heat utilization system, including a steam injector, the inlet of the steam injector is connected to the exhaust pipe of the low-pressure cylinder of the steam turbine, the steam injector is connected with a low-temperature water inlet pipe and a high-temperature water outlet pipe, and the low-temperature water inlet pipe The low-temperature water absorbs heat in the steam injector and turns into high-temperature water, and then it is discharged from the high-temperature water outlet pipe. The water inlet pipe is connected, the exhaust pipe of the low-pressure cylinder of the steam turbine is connected with the high-temperature heat source inlet of the heat-absorbing heat pump, and the low-temperature water inlet pipe and the medium-temperature water outlet pipe are connected to the heat-absorbing heat pump. Medium-temperature water is discharged from the medium-temperature water outlet pipe after the medium-heat absorption becomes medium-temperature water.

As a preference, a heat exchange plate is installed in the steam injector, a steam injection head is installed at the inner side of the air inlet of the steam injector, a diversion chamber is arranged in the heat exchange plate, and the liquid inlet end of the diversion chamber is connected to the low temperature The water inlet pipe is connected, the liquid outlet end of the diversion chamber is equipped with a water spray head, the heat exchange plate is provided with several through grooves, and the gas outlet of the steam ejector is equipped with a steam-water separator.

As a preference, the heat exchange plate is provided with several vertical grooves on the side facing the steam spray head, the grooves and through grooves are arranged alternately, and several fins separated from each other are installed in the grooves, and the two sides of the grooves A first through hole communicating with the through groove is provided.

As a preference, a flow regulating valve is installed on the high-temperature water outlet pipe. Through the control of the high-temperature water outlet flow, a certain amount of high-temperature water is stored at the bottom of the steam injector. The steam spray head is located below the high-temperature water liquid surface. Aeration discs are installed.

Preferably, the water spray head includes several water spray holes arranged side by side, the spray directions of adjacent water spray holes cross each other, and the spray directions of all the water spray holes are located in the same plane.

As a preference, a spiral guide tube is arranged inside the steam-water separator, and the spiral guide tube is connected to the inlet of the steam-water separator, and several second through holes are evenly arranged on the spiral guide tube, and the spiral guide tube is provided with a The arc-shaped baffle in the shape of a single-leaf hyperboloid, the outlet end of the spiral draft tube is provided with a flaring, and the flaring is located inside the arc-shaped baffle.

A control method for a steam turbine waste heat utilization system, comprising the following steps:

The high-temperature exhaust steam of the steam turbine is discharged from the exhaust pipe of the low-pressure cylinder of the steam turbine, and enters the steam injector for the first heat exchange with low-temperature water to produce high-temperature water. After the first heat exchange, the low-temperature exhaust steam enters the heat-absorbing heat pump, Using high-temperature exhaust steam as the driving heat source, low-temperature exhaust steam and low-temperature water conduct a second heat exchange to produce medium-temperature water, and the condensed water generated by the heat-absorbing heat pump is returned to the low-temperature water inlet pipe for recycling.

The beneficial effect brought by the adoption of the above technical solution is that the present invention adopts a two-stage heat exchange structure to fully recover the heat in exhaust steam. The first-stage heat exchange adopts the steam injection contact heat exchange method, and the second-stage heat exchange adopts the heat pump heat exchange method. For the steam injector, the present invention has carried out targeted improvement. The present invention abandons the way of direct steam injection for heat exchange, and first passes the high-temperature exhaust steam into the high-temperature water for the first heat exchange, the flow rate of the high-temperature exhaust steam flowing out of the high-temperature water is reduced, and the second heat exchange is performed on the surface of the heat exchange plate . Since the surface of the heat exchange plate is alternately arranged with grooves and through grooves, the high-temperature exhaust steam with a reduced flow rate can fully contact the fins in the grooves for heat exchange, and then flow through the heat exchange plate through the first through holes and through grooves. Reduce the turbulent flow generated by high-temperature exhaust steam in the heat exchange plate area. The high-temperature exhaust steam passing through the heat exchange plate performs a third heat exchange with the water jetted from the sprinkler head, and the spray from the sprinkler head can form a water curtain, thereby further improving the heat exchange efficiency between the exhaust steam and the water body. After three times of low-temperature heat exchange, the exhaust steam passes through the steam-water separator to separate water and then enters the heat pump. The high-temperature exhaust steam is used as the driving heat source, and the low-temperature exhaust steam is subjected to the fourth heat exchange, so as to make full use of the heat of exhaust steam. The steam-water separator is designed with an inner and outer two-layer separation structure, which can effectively improve the steam-water separation efficiency.

Description of drawings

Fig. 1 is a structural diagram of a specific embodiment of the present invention.

Fig. 2 is a structural diagram of a steam injector in a specific embodiment of the present invention.

Fig. 3 is a partially enlarged view of a heat exchange plate in a specific embodiment of the present invention.

Fig. 4 is a structural diagram of a steam-water separator in a specific embodiment of the present invention.

Detailed ways

With reference to Fig. 1-4, a specific embodiment of the present invention comprises steam injector 2, and the air inlet of steam injector 2 is connected with steam turbine low-pressure cylinder exhaust pipe 1, is connected with low-temperature water inlet pipe 3 and high-temperature water on steam injector 2. The water outlet pipe 4 and the low-temperature water in the low-temperature water inlet pipe 3 absorb heat in the steam ejector 2 and become high-temperature water and then discharge from the high-temperature water outlet pipe 4. The air outlet of the steam ejector 2 and the low temperature of the heat-absorbing heat pump 5 The heat source inlet is connected, the condensed water drain pipe 6 of the heat-absorbing heat pump 5 is connected with the low-temperature water inlet pipe 3, the exhaust pipe 1 of the low-pressure cylinder of the steam turbine is connected with the high-temperature heat source inlet of the heat-absorbing heat pump 5, and the heat-absorbing heat pump 5 is connected with Low-temperature water inlet pipe 3 and medium-temperature water outlet pipe 7, the low-temperature water in the low-temperature water inlet pipe 3 absorbs heat in the heat-absorbing heat pump 5 and becomes medium-temperature water and then discharges from the medium-temperature water outlet pipe 7. A heat exchange plate 8 is installed in the steam ejector 2, a steam injection head 9 is installed at the inner side of the air inlet of the steam ejector 2, a diversion chamber 10 is arranged in the heat exchange plate 8, and the liquid inlet end of the diversion chamber 10 Connected with the low-temperature water inlet pipe 3, the liquid outlet end of the diversion chamber 10 is equipped with a water spray head 11, the heat exchange plate 8 is provided with several through grooves 12, and the gas outlet of the steam ejector 2 is installed with a steam-water separator 13. The side of the heat exchange plate 8 facing the steam injection head 9 is provided with several vertical grooves 14, the grooves 14 are arranged alternately with the through grooves 12, and several mutually separated fins 15 are installed in the grooves 14, and the grooves Both sides of 14 are provided with a first through hole 16 communicating with the through groove 12 . A flow regulating valve 17 is installed on the high-temperature water outlet pipe 4. Through the control of the high-temperature water outlet flow, a certain amount of high-temperature water is stored at the bottom of the steam injector 2. The steam spray head 9 is located below the high-temperature water liquid surface. Aeration pan 18 is installed. The water spray head 11 includes several water spray holes 19 arranged side by side, the spray directions of adjacent water spray holes 19 cross each other, and the spray directions of all the water spray holes 19 are located in the same plane. The steam-water separator 13 is provided with a spiral guide tube 20, the spiral guide tube 20 is connected with the inlet of the steam-water separator 13, and several second through holes 21 are evenly arranged on the spiral guide tube 20, and the outer side of the spiral guide tube 20 An arc-shaped baffle 22 in the shape of a single-leaf hyperboloid is provided, and a flare 23 is provided at the outlet end of the spiral guide pipe 20 , and the flare 23 is located inside the arc-shaped baffle 22 .

A control method for the above steam turbine waste heat utilization system, comprising the following steps:

The high-temperature exhaust steam of the steam turbine is discharged from the exhaust pipe 1 of the low-pressure cylinder of the steam turbine, and enters the steam injector 2 for the first heat exchange with the low-temperature water to produce high-temperature water. The low-temperature exhaust steam after the first heat exchange enters the heat-absorbing type Heat pump 5 uses high-temperature exhaust steam as a driving heat source, and conducts second heat exchange between low-temperature exhaust steam and low-temperature water to produce medium-temperature water. The condensed water generated by heat-absorbing heat pump 5 is returned to low-temperature water inlet pipe 3 for recycling.

The invention can reach 45%-47% of the waste heat utilization rate of the high-temperature exhaust steam of the steam turbine, effectively improves the waste heat utilization rate of the exhaust steam of the steam turbine, and saves the operation cost of the power plant.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Variations and improvements are possible, which fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (7)

1. A steam turbine waste heat utilization system is characterized in that: comprise a steam injector (2), the air inlet of the steam injector (2) is connected with the steam turbine low-pressure cylinder exhaust pipe (1), and the steam injector (2) Connected with a low-temperature water inlet pipe (3) and a high-temperature water outlet pipe (4), the low-temperature water in the low-temperature water inlet pipe (3) absorbs heat in the steam injector (2) and becomes high-temperature water from the high-temperature water outlet pipe ( 4) Exhaust, the air outlet of the steam ejector (2) is connected to the low-temperature heat source inlet of the heat-absorbing heat pump (5), and the condensate drain pipe (6) of the heat-absorbing heat pump (5) is connected to the low-temperature water inlet pipe (3) The exhaust pipe (1) of the low-pressure cylinder of the steam turbine is connected with the high-temperature heat source inlet of the heat-absorbing heat pump (5), and the heat-absorbing heat pump (5) is connected with a low-temperature water inlet pipe (3) and a medium-temperature water outlet pipe (7) , the low-temperature water in the low-temperature water inlet pipe (3) absorbs heat in the heat-absorbing heat pump (5) and becomes medium-temperature water and then discharges from the medium-temperature water outlet pipe (7). 2. The steam turbine waste heat utilization system according to claim 1, characterized in that: a heat exchange plate (8) is installed in the steam ejector (2), and a spray nozzle is installed at the inner side of the air inlet of the steam ejector (2). The steam head (9), the heat exchange plate (8) is provided with a diversion chamber (10), the liquid inlet end of the diversion chamber (10) is connected with the low-temperature water inlet pipe (3), and the diversion chamber (10 ) is equipped with a water spray head (11), the heat exchange plate (8) is provided with several through grooves (12), and a steam separator (13) is installed on the gas outlet of the steam injector (2). 3. The steam turbine waste heat utilization system according to claim 2, characterized in that: the side of the heat exchange plate (8) facing the steam injection head (9) is provided with several vertical grooves (14). The slots (14) and through slots (12) are alternately arranged, and several fins (15) separated from each other are installed in the slots (14). The first through hole (16). 4. The steam turbine waste heat utilization system according to claim 3, characterized in that: the high-temperature water outlet pipe (4) is equipped with a flow regulating valve (17), and through the control of the high-temperature water outlet flow, the steam ejector ( 2) There is a certain amount of high-temperature water stored at the bottom, and the steam spray head (9) is located below the liquid surface of the high-temperature water, and an aeration disc (18) is installed on the steam spray head (9). 5. The steam turbine waste heat utilization system according to claim 4, characterized in that: the water spray head (11) includes several water spray holes (19) arranged side by side, and the spray direction of adjacent water spray holes (19) Intersect each other, and the injection directions of all spray holes (19) are located in the same plane. 6. The steam turbine waste heat utilization system according to claim 5, characterized in that: the steam-water separator (13) is provided with a spiral guide pipe (20), and the spiral guide pipe (20) and the steam-water separator (13 ), a number of second through-holes (21) are evenly arranged on the spiral draft pipe (20), and a single-leaf hyperboloid arc-shaped baffle (22) is arranged on the outer side of the spiral draft pipe (20). The outlet end of the spiral draft pipe (20) is provided with a flared mouth (23), and the flared mouth (23) is located inside the arc-shaped baffle (22). 7. A control method for a steam turbine waste heat utilization system, characterized in that it comprises the following steps: The high-temperature exhaust steam of the steam turbine is discharged from the exhaust pipe (1) of the low-pressure cylinder of the steam turbine, and enters the steam injector (2) for the first heat exchange with low-temperature water to produce high-temperature water, and the low-temperature exhaust steam after the first heat exchange Enter the heat-absorbing heat pump (5), use the high-temperature exhaust steam as the driving heat source, and conduct a second heat exchange between the low-temperature exhaust steam and the low-temperature water to obtain medium-temperature water, and the condensed water generated by the heat-absorbing heat pump (5) flows back to the low-temperature water The water inlet pipe (3) is recycled.

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