A gas-steam combined cycle unit cold end temperature control system and method

Abstract

The present invention discloses a cold end temperature control system and method for a gas-steam combined cycle unit. A heat exchanger is arranged at the air inlet end of a compressor. The generator inlet of an absorption heat pump is connected to a low-pressure drum of a waste heat boiler through a pipeline. The condenser outlet is connected to a hot inlet of a cooling device. The condenser inlet is connected to a hot outlet of a cooling device. The evaporator outlet is connected to a cold inlet of a heat exchanger. The evaporator inlet is connected to a cold outlet of the heat exchanger. A booster pump and a first regulating valve are arranged on the pipeline connected to the condenser outlet. A feed water pump and a second regulating valve are arranged on the pipeline connected to the condenser inlet of the absorption heat pump. A circulating pump and a third regulating valve are arranged on the pipeline connected to the evaporator outlet. A fourth regulating valve is arranged on the pipeline connected to the evaporator inlet. A fifth regulating valve is arranged on the pipeline connected to the generator inlet. The present invention can completely solve the problem that the power generation and power generation efficiency of a gas-steam combined cycle unit are affected by the change of the cold end air temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of power generation of gas-steam combined cycle units, and in particular relates to a cold end temperature control system and method for a gas-steam combined cycle unit. Background Art

[0002] Natural gas power generation is flexible in start and stop, has strong load adaptability, can meet the needs of rapid peak and frequency regulation of the power grid, and helps to improve the safety of the power grid. At the same time, as a clean energy, natural gas power generation can effectively optimize and adjust the energy structure, and its proportion in primary energy consumption continues to rise. Gas-steam combined cycle units represented by natural gas power generation have the characteristics of high efficiency, cleanliness, stability, and high degree of integration, and have been valued by power generation companies at home and abroad. Therefore, energy-saving research on gas-steam combined cycle units has great practical significance. The ambient temperature is the most critical external factor affecting the power generation and power generation efficiency of gas-steam combined cycle units. When the temperature rises, the air density decreases, the mass flow rate decreases, the power consumption of the compressor increases, the gas exhaust temperature increases, and the steam side will overheat. The power generation and power generation efficiency of the entire combined cycle system decrease. For example, if the temperature drops by 2 to 3°C in summer, the overall power generation will increase by 1.3% to 1.5%, and the overall efficiency will increase by 0.15% to 0.18%. However, when the temperature reduction is too large, water will condense in the air due to the influence of ambient air humidity. If the condensed water enters the compressor and the combustion chamber of the gas turbine, the efficiency brought by the cooling effect will be greatly reduced. Therefore, the control and dehumidification of the cold end inlet temperature during the operation of the gas-steam combined unit is particularly important. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention proposes a cold-end temperature control system and method for a gas-steam combined cycle unit. The present invention can completely solve the problems existing in the current gas-steam combined cycle unit such as the change of the cold-end air temperature affecting the unit's power generation and the decrease in power generation efficiency.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A cold-end temperature control system for a gas-steam combined cycle unit comprises a compressor, a combustion chamber of a gas turbine, a waste heat boiler, an absorption heat pump, a cooling device and a heat exchanger, wherein the compressor, the combustion chamber of the gas turbine and the waste heat boiler are connected in sequence, the heat exchanger is arranged at the air inlet end of the compressor, the generator inlet of the absorption heat pump is connected to the low-pressure drum of the waste heat boiler through a pipeline, the condenser outlet of the absorption heat pump is connected to the hot inlet of the cooling device, the hot outlet of the cooling device is connected to the condenser inlet of the absorption heat pump, the evaporator outlet of the absorption heat pump is connected to the cold inlet of the heat exchanger, and the cold outlet of the heat exchanger is connected to the evaporator inlet of the absorption heat pump;

[0006] A booster pump is provided on the pipeline connecting the condenser outlet of the absorption heat pump and the hot inlet of the cooling device, and a first regulating valve is provided at the outlet of the booster pump; a feed water pump is provided on the pipeline connecting the hot outlet of the cooling device and the condenser inlet of the absorption heat pump, and a second regulating valve is provided at the outlet of the feed water pump; a circulation pump is provided on the pipeline connecting the evaporator outlet of the absorption heat pump and the cold inlet of the heat exchanger, and a third regulating valve is provided at the outlet of the circulation pump, a fourth regulating valve is provided on the pipeline connecting the cold outlet of the heat exchanger and the evaporator inlet of the absorption heat pump, and a fifth regulating valve is provided on the pipeline connecting the generator inlet of the absorption heat pump and the low-pressure steam drum of the waste heat boiler.

[0007] Preferably, the first regulating valve, the second regulating valve, the third regulating valve, the fourth regulating valve and the fifth regulating valve are all electric regulating valves.

[0008] Preferably, the cooling device is a cooling tower.

[0009] Preferably, the heat exchanger comprises a heat exchanger shell and a plurality of air heat exchange plates and water side heat exchange plates sequentially stacked in the heat exchanger shell, the air heat exchange plates and the water side heat exchange plates each comprising a heat exchange bottom plate, the heat exchange bottom plate being provided with a plurality of rows of raised inner plates, each row of inner plates comprising a plurality of inner plates, each inner plate being in a streamlined shape with a large middle portion and small ends;

[0010] The top of the inner sheet on the heat exchange bottom plate of the air heat exchange plate abuts against the heat exchange bottom plate of the water side heat exchange plate adjacent to the air heat exchange plate, and the cavity between the heat exchange bottom plate of the air heat exchange plate and the heat exchange bottom plate of the water side heat exchange plate is an air flow cavity, and the air flow cavity is used for air flow; in the air flow cavity, the long axis direction of the inner sheet is arranged along the direction of air flow;

[0011] The top of the inner plate on the heat exchange bottom plate of the water side heat exchange plate abuts against the heat exchange bottom plate of the air heat exchange plate adjacent to the water side heat exchange plate, and the cavity between the heat exchange bottom plate of the water side heat exchange plate and the heat exchange bottom plate of the air heat exchange plate is a cooling water flow cavity, and the cooling water flow cavity is used for cooling water to flow; in the cooling water flow cavity, the long axis direction of the inner plate is arranged along the direction of cooling water flow;

[0012] The air flow chamber and the cooling water flow chamber are isolated from each other;

[0013] The heat exchanger shell is provided with an air inlet, an air outlet, a cooling water inlet and a cooling water outlet. The side where air enters all air flow cavities is connected to the air inlet, the side where air flows out of all air flow cavities is connected to the air outlet, the side where cooling water enters all cooling water flow cavities is connected to the cooling water inlet, and the side where cooling water flows out of all cooling water flow cavities is connected to the cooling water outlet.

[0014] Preferably, the flow direction of the air in the air flow cavity and the flow direction of the cooling water in the cooling water flow cavity are perpendicular to each other.

[0015] Preferably, the inner plates on the heat exchange bottom plate of the air heat exchange plate are distributed in an array;

[0016] The inner plates on the heat exchange bottom plate of the water side heat exchange plate are distributed in a staggered manner, and the staggered distance is half the length of the long axis of the inner plate plus half the width of the gap.

[0017] Preferably, condensate guide grooves are provided on both sides of each row of inner plates on the heat exchange base plate of the air heat exchange plate, and condensate confluence grooves are provided on the air outlet side of the air flow cavity on the heat exchange base plate of the air heat exchange plate. The ends of all condensate guide grooves located on the air outlet side of the air flow cavity on the heat exchange base plate of the air heat exchange plate are connected to the condensate confluence grooves, and the condensate confluence grooves are used to discharge the converged condensate to the outside of the heat exchanger.

[0018] Preferably, the inner sheet is a section of an elliptical cylinder, and for a single elliptical inner sheet, the following relationship is satisfied:

[0019] 1.2≤H / d≤1.5;

[0020] Two adjacent inner slices satisfy the following relationship:

[0021] d≤cotA*(L / 2+H / 2)≤2d

[0022] Among them, H is the length of the major axis of the cross section of the elliptical cylinder, d is the length of the minor axis of the cross section of the elliptical cylinder, L is the clear distance between two adjacent elliptical cylinders in the same row, and A is the angle between the intangent line of two adjacent elliptical cylinders in the same row and the minor axis of the elliptical cylinder.

[0023] The working method of the cold end temperature control system of the gas-steam combined cycle unit of the present invention comprises the following process:

[0024] When the temperature at the compressor inlet end is higher than the preset value, start the absorption heat pump, open the fifth regulating valve, and use the steam in the low-pressure drum of the waste heat boiler to start the absorption heat pump; open the first regulating valve, the second regulating valve, the third regulating valve, the fourth regulating valve, start the booster pump, the feed water pump and the circulating pump, and reduce the air temperature at the compressor inlet end to the preset range through the heat exchanger 6.

[0025] Preferably, the heat exchanger comprises a heat exchanger shell and a plurality of air heat exchange plates and water side heat exchange plates sequentially stacked in the heat exchanger shell, the air heat exchange plates and the water side heat exchange plates each comprising a heat exchange bottom plate, the heat exchange bottom plate being provided with a plurality of rows of raised inner plates, each row of inner plates comprising a plurality of inner plates, each inner plate being in a streamlined shape with a large middle portion and small ends;

[0026] The top of the inner sheet on the heat exchange bottom plate of the air heat exchange plate abuts against the heat exchange bottom plate of the water side heat exchange plate adjacent to the air heat exchange plate, and the cavity between the heat exchange bottom plate of the air heat exchange plate and the heat exchange bottom plate of the water side heat exchange plate is an air flow cavity, and the air flow cavity is used for air flow; in the air flow cavity, the long axis direction of the inner sheet is arranged along the direction of air flow;

[0027] The top of the inner plate on the heat exchange bottom plate of the water side heat exchange plate abuts against the heat exchange bottom plate of the air heat exchange plate adjacent to the water side heat exchange plate, and the cavity between the heat exchange bottom plate of the water side heat exchange plate and the heat exchange bottom plate of the air heat exchange plate is a cooling water flow cavity, and the cooling water flow cavity is used for cooling water to flow; in the cooling water flow cavity, the long axis direction of the inner plate is arranged along the direction of cooling water flow;

[0028] The air flow chamber and the cooling water flow chamber are isolated from each other;

[0029] The heat exchanger shell is provided with an air inlet, an air outlet, a cooling water inlet and a cooling water outlet. The side where air enters all air flow chambers is connected to the air inlet, the side where air flows out of all air flow chambers is connected to the air outlet, the side where cooling water enters all cooling water flow chambers is connected to the cooling water inlet, and the side where cooling water flows out of all cooling water flow chambers is connected to the cooling water outlet;

[0030] Condensate guide grooves are provided on both sides of each row of inner plates on the heat exchange bottom plate of the air heat exchange plate, and condensate confluence grooves are provided on the air outlet side of the air flow cavity on the heat exchange bottom plate of the air heat exchange plate. The ends of all condensate guide grooves located on the air outlet side of the air flow cavity on the heat exchange bottom plate of the air heat exchange plate are connected to the condensate confluence grooves, and the condensate confluence grooves are used to guide the confluenced condensate to the outside of the heat exchanger;

[0031] When the air temperature at the compressor inlet end is reduced to a preset range through the heat exchanger 6, the condensed water generated by the air cooling is collected through the condensed water guide groove and then merged into the condensed water confluence groove, and the merged condensed water is discharged to the outside of the heat exchanger through the condensed water confluence groove.

[0032] The present invention has the following beneficial effects:

[0033] In the cold-end temperature control system of the gas-steam combined cycle unit of the present invention, a heat exchanger is used to cool the air temperature at the air inlet end of the compressor to a preset range when the outside temperature is high, thereby improving the power generation and efficiency as a whole. The system has the characteristics of simple process flow, mature equipment, low investment cost, and good economic benefits, and completely solves the problem that the current gas-steam combined cycle unit is affected by the change of the cold-end air temperature and the power generation of the unit is affected and the power generation efficiency is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1It is a structural schematic diagram of the cold end temperature control system of the gas-steam combined cycle unit of the present invention;

[0035] FIG. 2( a ) is a top view of a heat exchanger of the present invention; FIG. 2( b ) is a perspective view of a heat exchanger of the present invention;

[0036] Figure 3 It is a schematic diagram of the structure of the air heat exchange plate of the present invention;

[0037] Figure 4 It is a schematic diagram of the structure of the water side heat exchange plate of the present invention;

[0038] Figure 5 It is a schematic diagram of the arrangement of adjacent inner plates in the air side heat exchange plate and the water side heat exchange plate of the present invention.

[0039] Among them: 1 is a compressor; 2 is a combustion chamber of a gas turbine; 3 is a waste heat boiler; 4 is a steam turbine; 5 is a generator; 6 is a heat exchanger; 6-1 is an air heat exchange plate; 6-1-1 is an in-line inner plate; 6-1-2 is a condensate guide groove; 6-1-3 is a condensate confluence groove; 6-2 is a water side heat exchange plate; 6-2-1 is a staggered inner plate; 7 is an absorption heat pump; 8 is a booster pump; 9 is a first regulating valve; 10 is a cooling tower; 11 is a feed water pump; 12 is a second regulating valve; 13 is a circulating pump; 14 is a third regulating valve; 15 is a fourth regulating valve; 16 is a fifth regulating valve. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0041] See also Figure 1The cold end temperature control system of the gas-steam combined cycle unit of the present invention comprises a compressor 1, a combustion chamber of a gas turbine 2, a waste heat boiler 3, an absorption heat pump 7, a cooling device and a heat exchanger 6. The compressor 1, the combustion chamber of the gas turbine 2 and the waste heat boiler 3 are connected in sequence. The heat exchanger 6 is arranged at the air inlet end of the compressor 1. The generator inlet of the absorption heat pump 7 is connected to the low-pressure drum of the waste heat boiler 3 through a pipeline. The condenser outlet of the absorption heat pump 7 is connected to the hot inlet of the cooling device. The hot outlet of the cooling device is connected to the condenser inlet of the absorption heat pump 7. The evaporator outlet of the absorption heat pump 7 is connected to the cold inlet of the heat exchanger 6. The cold outlet of the heat exchanger 6 is connected to the evaporator inlet of the absorption heat pump 7. A booster pump 8 is provided on the pipeline connecting the condenser outlet of the heat pump 7 and the hot inlet of the cooling device, and a first regulating valve 9 is provided at the outlet of the booster pump 8; a feed water pump 11 is provided on the pipeline connecting the hot outlet of the cooling device and the condenser inlet of the absorption heat pump 7, and a second regulating valve 12 is provided at the outlet of the feed water pump 11; a circulation pump 13 is provided on the pipeline connecting the evaporator outlet of the absorption heat pump 7 and the cold inlet of the heat exchanger 6, and a third regulating valve 14 is provided at the outlet of the circulation pump 13; a fourth regulating valve 15 is provided on the pipeline connecting the cold outlet of the heat exchanger 6 and the evaporator inlet of the absorption heat pump 7; a fifth regulating valve 16 is provided on the pipeline connecting the generator inlet of the absorption heat pump 7 and the low-pressure drum of the waste heat boiler 3. The cooling device adopts a cooling tower 10, and the absorption heat pump 7, the cooling tower 10, and the heat exchanger 6 form a closed loop to realize the closed circulation of refrigerated water; the driving source of the absorption heat pump 7 comes from the steam in the low-pressure drum of the waste heat boiler 3. The first regulating valve 9, the second regulating valve 12, the third regulating valve 14, the fourth regulating valve 15 and the fifth regulating valve 16 are all electric regulating valves, which are convenient for automatic and precise control. The compressor 1, the combustion chamber 2 of the gas turbine, the steam turbine 3 and the generator 5 are coaxially arranged.

[0042] The working method of the cold end temperature control system of the gas-steam combined cycle unit of the present invention comprises the following process:

[0043] When the temperature at the air inlet of the compressor 1 is higher than the preset value (such as when the ambient temperature is high in summer), the absorption heat pump 7 is started, the fifth regulating valve 16 is opened, and the steam in the low-pressure drum of the waste heat boiler 3 starts the absorption heat pump 7 to operate; the first regulating valve 9, the second regulating valve 12, the third regulating valve 14, the fourth regulating valve 15 are opened, the booster pump 8, the feed water pump 11 and the circulating pump 13 are started, and the air temperature at the air inlet of the compressor 1 is reduced to the preset range through the heat exchanger 6. The system heat circulates through the cooling device and continuously transports the heat to the outside.

[0044] See also Figure 2(a) to Figure 4The heat exchanger 6 provided by the present invention comprises a heat exchanger shell and a plurality of air heat exchange plates 6-1 and water side heat exchange plates 6-2 stacked in sequence in the heat exchanger shell. The air heat exchange plates 6-1 and the water side heat exchange plates 6-2 both comprise a heat exchange bottom plate. The heat exchange bottom plate is provided with a plurality of rows of raised inner plates. Each row of inner plates comprises a plurality of inner plates. The shape of each inner plate is a streamlined shape with a large middle and small ends. The top of the inner plate on the heat exchange bottom plate of the air heat exchange plate 6-1 abuts against the heat exchange bottom plate of the water side heat exchange plate 6-2 adjacent to the air heat exchange plate 6-1. The cavity between the heat exchange bottom plate of the air heat exchange plate 6-1 and the heat exchange bottom plate of the water side heat exchange plate 6-2 is an air flow cavity, and the air flow cavity is used for air flow. In the air flow cavity, the long axis direction of the inner plate is arranged along the direction of air flow.

[0045] The top of the inner plate on the heat exchange bottom plate of the water-side heat exchange plate 6-2 is abutted against the heat exchange bottom plate of the air heat exchange plate 6-1 adjacent to the water-side heat exchange plate 6-2. The cavity between the heat exchange bottom plate of the water-side heat exchange plate 6-2 and the heat exchange bottom plate of the air heat exchange plate 6-1 is a cooling water flow cavity, which is used for cooling water flow. In the cooling water flow cavity, the long axis direction of the inner plate is arranged along the direction of cooling water flow. The air flow cavity and the cooling water flow cavity are isolated from each other. An air inlet, an air outlet, a cooling water inlet and a cooling water outlet are arranged on the heat exchanger shell. The side where air enters all air flow cavities is connected to the air inlet, the side where air flows out of all air flow cavities is connected to the air outlet, the side where cooling water enters all cooling water flow cavities is connected to the cooling water inlet, and the side where cooling water flows out of all cooling water flow cavities is connected to the cooling water outlet. In the heat exchanger 6 of the above structure of the present invention, the shape of each inner plate is a streamlined type with a large middle and small ends. Under the same circumference conditions, the cross-sectional area of ​​the inner plate of this shape is smaller than that of the circular tube. If the flow rate remains unchanged, the disturbance is enhanced, and the convective heat transfer effect is enhanced. At the same time, the flow channel of the inner plate of this shape is streamlined, and the resistance is small when the fluid sweeps outward. The flow velocity will increase under the same flow resistance, so the external heat transfer effect is also enhanced. The flow channel of the inner plate of this shape has good flow characteristics. When the fluid sweeps along the long axis direction of the inner plate of this shape, the separation point moves backward relative to the circular channel, and the flow loss caused by the Karman vortex street in the separation area will be greatly reduced, thereby reducing heat loss and improving heat exchange efficiency.

[0046] Referring to FIG. 2(a) and FIG. 2(b), the present invention provides a method in which the flow direction of air in the air flow cavity and the flow direction of cooling water in the cooling water flow cavity can be set to be perpendicular to each other, so that the air and water are arranged crosswise along the axial direction and the longitudinal direction, achieving high efficiency and low end difference heat exchange efficiency of air and water.

[0047] For further information, see Figure 3 and Figure 4The inner plates on the heat exchange bottom plate of the air heat exchange plate 6-1 are distributed in an array form, and the inner plates on the air heat exchange plate 6-1 of this type can also be called in-line inner plates 6-1-1; the inner plates on the heat exchange bottom plate of the water side heat exchange plate 6-2 are distributed in a staggered form, and the inner plates on the water side heat exchange plate 6-2 of this type can be called staggered inner plates 6-2-1, see Figure 5 The space between two adjacent inner sheets (the space between the lower end of the long axis of the upper inner sheet and the upper end of the long axis of the lower inner sheet) is called the seam between the two inner sheets. Figure 4 Take the position shown as an example. Figure 4 In the figure, the midline of the seam between the top two inner sheets of the first row of inner sheets on the left is aligned with the short axis of the second inner sheet from the top to the bottom of the second row of inner sheets on the left. Figure 5 For example, the midline of the seam between two inner sheets refers to the line passing through the midpoint O of the seam and perpendicular to the long axes of the two inner sheets. The midpoint O of the seam is the midpoint of the connection between the lower end of the long axis of the upper inner sheet and the upper end of the long axis of the lower inner sheet. The offset is half the length of the long axis of the inner sheet plus half the width of the seam, where Figure 4 Taking the first column of inner plates and the second column of inner plates on the left side as examples, the offset distance refers to the distance between the midline of the seam of the inner plates in the first column and the midline of the seam of the inner plates in the second column and the offset in the column direction. Specifically, it can be understood as follows: before the offset, the distribution form of the inner plates on the water side heat exchange plate 6-2 is a neat matrix (determinant) form, in which every other column, the inner plates in one column are translated upward as a whole by half the seam width plus half the distance of the major axis, such as Figure 4 In the figure, the even columns are shifted upward relative to the odd columns by half the slit width plus half the major axis.

[0048] The air heat exchange plate 6-1 of the above structure ensures that the flow of air in the air flow cavity is heat exchanged while further reducing the flow resistance, so that the air can flow in the air flow cavity in a low-resistance mode, thereby ensuring the air intake of the compressor 1. The water side heat exchange plate 6-2 of the above structure allows the air to fully absorb heat when flowing in the cooling water flow cavity during cooling, thereby improving the air side heat exchange effect. The air heat exchange plate 6-1 and the water side heat exchange plate 6-2 of the above structure ensure that the system of the present invention does not affect the safe and stable operation of the gas-steam combined cycle unit.

[0049] See also Figure 3In order to discharge the condensed water in the air well without affecting the air flow resistance and the engine benefits brought by cooling, the heat exchange bottom plate of the air heat exchange plate 6-1 of the present invention is provided with condensed water guide grooves 6-1-2 on both sides of each row of inner plates, and the heat exchange bottom plate of the air heat exchange plate 6-1 is provided with condensed water converging grooves 6-1-3 on the air outlet side of the air flow cavity. The ends of all the condensed water guide grooves 6-1-2 located on the air outlet side of the air flow cavity on the heat exchange bottom plate of the air heat exchange plate 6-1 are connected to the condensed water converging grooves 6-1-3, and the condensed water converging grooves 6-1-3 are used to guide the converged condensed water to the outside of the heat exchanger 6. When the air in the air flow cavity is cooled and condensed water is generated, the condensed water on the inner plate and the heat exchange bottom plate will first flow into the condensed water guide groove 6-1-2, and then the condensed water will be introduced into the condensed water confluence groove 6-1-3 through the condensed water guide groove 6-1-2, and finally the generated condensed water will be discharged to the outside of the heat exchanger 6 through the condensed water confluence groove 6-1-3, so as to achieve air-water separation. Therefore, the present invention can effectively prevent condensed water from entering the compressor and the gas turbine combustion chamber, thereby avoiding the greatly reduced efficiency caused by the cooling effect on the air at the compressor intake end.

[0050] See also Figure 5 The inner plate of the present invention adopts a section of elliptical cylinder, which, on the one hand, reduces the influence of Karman vortex street on flow and heat transfer, and on the other hand, improves the heat transfer effect of the two sides, improves the heat transfer efficiency as much as possible, reduces the heat transfer end difference, and better reduces the volume of the heat exchanger. In order to achieve the above functional effects, for a single elliptical inner plate, the length of the major axis H of the cross section of the elliptical cylinder and the length of the minor axis d of the cross section of the elliptical cylinder satisfy the following relationship:

[0051] 1.2≤H / d≤1.5 (1)

[0052] If H / d is less than 1.2, the elliptical inner plate is close to a circle, which strengthens the influence of the Karman vortex street formed by the fluid flowing through. If H / d is greater than 1.5, the elliptical inner plate is slender, which is not conducive to the fluid flowing around and enhancing heat transfer.

[0053] For the arrangement of the elliptical inner sheets, the horizontal arrangement mainly ensures low air resistance, and the design principle of flow rate less than 2m / s and resistance less than 100Pa is selected to calculate the effective fluid area. In the longitudinal direction (i.e., the column direction), in order to achieve heat exchange efficiency and reduce the fluid resistance between the elliptical inner sheets, the two adjacent inner sheets meet the following relationship:

[0054] d≤cotA*(L / 2+H / 2)≤2d (2)

[0055] Wherein, L is the clear distance between two adjacent elliptical cylinders in the same row of slices, and A is the angle between the intangent line of two adjacent elliptical cylinders in the same row of slices and the minor axis of the elliptical cylinder;

[0056] The distribution form of the air heat exchange plate 6-1 on the heat exchange bottom plate of the present invention must meet the requirements of formula (1) and formula (2), combined with Figure 5 When the air flows through the first inner plate from top to bottom, the air velocity first slowly increases, then slowly decreases after passing the short axis of the inner plate, and finally mixes at a relatively low velocity in the area of ​​the two inner plates, flows through the next inner plate after mixing, and repeats the above process of flowing through the first inner plate. Therefore, the air heat exchange plate 6-1 of the present invention ensures the low resistance characteristics and the bypass characteristics of the fluid flow, so that the air has a low resistance in the air flow cavity and can be mixed more fully, which is conducive to improving the heat exchange efficiency with water.

[0057] The cold-end temperature control system of the gas-steam combined cycle unit proposed in the present invention realizes the high-efficiency operation mode of the gas-steam combined cycle unit in summer by adopting three key technologies: low-resistance heat exchanger, low-end difference gas-water cross heat exchange, and unit coupling high-efficiency heat pump system.

Claims

1. A cold end temperature control system for a gas-steam combined cycle unit. It is characterized in that The invention comprises a compressor (1), a combustion chamber of a gas turbine (2), a waste heat boiler (3), an absorption heat pump (7), a cooling device and a heat exchanger (6); the compressor (1), the combustion chamber of the gas turbine (2) and the waste heat boiler (3) are connected in sequence; the heat exchanger (6) is arranged at the air inlet end of the compressor (1); the generator inlet of the absorption heat pump (7) is connected to the low-pressure drum of the waste heat boiler (3) through a pipeline; the condenser outlet of the absorption heat pump (7) is connected to the hot inlet of the cooling device; the hot outlet of the cooling device is connected to the condenser inlet of the absorption heat pump (7); the evaporator outlet of the absorption heat pump (7) is connected to the cold inlet of the heat exchanger (6); and the cold outlet of the heat exchanger (6) is connected to the evaporator inlet of the absorption heat pump (7); A booster pump (8) is provided on a pipeline connecting the condenser outlet of the absorption heat pump (7) and the heat inlet of the cooling device, and a first regulating valve (9) is provided at the outlet of the booster pump (8); a feed water pump (11) is provided on a pipeline connecting the heat outlet of the cooling device and the condenser inlet of the absorption heat pump (7), and a second regulating valve (12) is provided at the outlet of the feed water pump (11); a circulation pump (13) is provided on a pipeline connecting the evaporator outlet of the absorption heat pump (7) and the cold inlet of the heat exchanger (6), and a third regulating valve (14) is provided at the outlet of the circulation pump (13); a fourth regulating valve (15) is provided on a pipeline connecting the cold outlet of the heat exchanger (6) and the evaporator inlet of the absorption heat pump (7); and a fifth regulating valve (16) is provided on a pipeline connecting the generator inlet of the absorption heat pump (7) and the low-pressure drum of the waste heat boiler (3).

2. A gas-steam combined cycle unit cold end temperature control system according to claim 1, It is characterized in that The first regulating valve (9), the second regulating valve (12), the third regulating valve (14), the fourth regulating valve (15) and the fifth regulating valve (16) are all electric regulating valves.

3. A gas-steam combined cycle unit cold end temperature control system according to claim 1, It is characterized in that The cooling device adopts a cooling tower (10).

4. A gas-steam combined cycle unit cold end temperature control system according to claim 1, It is characterized in that The heat exchanger (6) comprises a heat exchanger shell and a plurality of air heat exchange plates (6-1) and water side heat exchange plates (6-2) stacked in sequence in the heat exchanger shell, the air heat exchange plates (6-1) and the water side heat exchange plates (6-2) both comprising a heat exchange bottom plate, the heat exchange bottom plate being provided with a plurality of rows of raised inner plates, each row of inner plates comprising a plurality of inner plates, each inner plate being in a streamlined shape with a large middle portion and small ends; The top of the inner plate on the heat exchange bottom plate of the air heat exchange plate (6-1) abuts against the heat exchange bottom plate of the water side heat exchange plate (6-2) adjacent to the air heat exchange plate (6-1); the cavity between the heat exchange bottom plate of the air heat exchange plate (6-1) and the heat exchange bottom plate of the water side heat exchange plate (6-2) is an air flow cavity, and the air flow cavity is used for air flow; in the air flow cavity, the long axis direction of the inner plate is arranged along the direction of air flow; The top of the inner plate on the heat exchange bottom plate of the water side heat exchange plate (6-2) abuts against the heat exchange bottom plate of the air heat exchange plate (6-1) adjacent to the water side heat exchange plate (6-2); the cavity between the heat exchange bottom plate of the water side heat exchange plate (6-2) and the heat exchange bottom plate of the air heat exchange plate (6-1) is a cooling water flow cavity, and the cooling water flow cavity is used for cooling water flow; in the cooling water flow cavity, the long axis direction of the inner plate is arranged along the direction of cooling water flow; The air flow chamber and the cooling water flow chamber are isolated from each other; The heat exchanger shell is provided with an air inlet, an air outlet, a cooling water inlet and a cooling water outlet. The side where air enters all air flow cavities is connected to the air inlet, the side where air flows out of all air flow cavities is connected to the air outlet, the side where cooling water enters all cooling water flow cavities is connected to the cooling water inlet, and the side where cooling water flows out of all cooling water flow cavities is connected to the cooling water outlet.

5. A gas-steam combined cycle unit cold end temperature control system according to claim 4, It is characterized in that The flow direction of the air in the air flow cavity and the flow direction of the cooling water in the cooling water flow cavity are perpendicular to each other.

6. A gas-steam combined cycle unit cold end temperature control system according to claim 4, It is characterized in that The inner plates on the heat exchange bottom plate of the air heat exchange plate (6-1) are distributed in an array form; The inner plates on the heat exchange bottom plate of the water side heat exchange plate (6-2) are distributed in a staggered manner, and the staggered distance is half the length of the long axis of the inner plate plus half the width of the gap.

7. A gas-steam combined cycle unit cold end temperature control system according to claim 4, It is characterized in that Condensate guide grooves (6-1-2) are provided on both sides of each row of inner plates on the heat exchange bottom plate of the air heat exchange plate (6-1), and condensate converging grooves (6-1-3) are provided on the heat exchange bottom plate of the air heat exchange plate (6-1) on the air outlet side of the air flow cavity. The ends of all condensate guide grooves (6-1-2) located on the heat exchange bottom plate of the air heat exchange plate (6-1) on the air outlet side of the air flow cavity are connected to the condensate converging grooves (6-1-3), and the condensate converging grooves (6-1-3) are used to guide the converged condensate to the outside of the heat exchanger (6).

8. A gas-steam combined cycle unit cold end temperature control system according to claim 4, It is characterized in that The inner piece adopts a section of elliptical cylinder. For a single elliptical inner piece, the following relationship is satisfied: 1.2≤H / d≤1.5 Two adjacent inner slices satisfy the following relationship: d≤cotA*(L / 2+H / 2)≤2d Among them, H is the length of the major axis of the cross section of the elliptical cylinder, d is the length of the minor axis of the cross section of the elliptical cylinder, L is the clear distance between two adjacent elliptical cylinders in the same row, and A is the angle between the intangent line of two adjacent elliptical cylinders in the same row and the minor axis of the elliptical cylinder.

9. A working method of a cold end temperature control system of a gas-steam combined cycle unit according to any one of claims 1 to 8, It is characterized in that The process includes the following: When the temperature at the air inlet end of the compressor (1) is higher than a preset value, the absorption heat pump (7) is started, the fifth regulating valve (16) is opened, and the steam in the low-pressure drum of the waste heat boiler (3) starts the absorption heat pump (7) to operate; the first regulating valve (9), the second regulating valve (12), the third regulating valve (14), and the fourth regulating valve (15) are opened, the booster pump (8), the feed water pump (11) and the circulation pump (13) are started, and the air temperature at the air inlet end of the compressor (1) is reduced to a preset range through the heat exchanger (6).

10. The working method of the cold end temperature control system of a gas-steam combined cycle unit according to claim 9, It is characterized in that The heat exchanger (6) comprises a heat exchanger shell and a plurality of air heat exchange plates (6-1) and water side heat exchange plates (6-2) stacked in sequence in the heat exchanger shell, the air heat exchange plates (6-1) and the water side heat exchange plates (6-2) both comprising a heat exchange bottom plate, the heat exchange bottom plate being provided with a plurality of rows of raised inner plates, each row of inner plates comprising a plurality of inner plates, each inner plate being in a streamlined shape with a large middle portion and small ends; The top of the inner plate on the heat exchange bottom plate of the air heat exchange plate (6-1) abuts against the heat exchange bottom plate of the water side heat exchange plate (6-2) adjacent to the air heat exchange plate (6-1); the cavity between the heat exchange bottom plate of the air heat exchange plate (6-1) and the heat exchange bottom plate of the water side heat exchange plate (6-2) is an air flow cavity, and the air flow cavity is used for air flow; in the air flow cavity, the long axis direction of the inner plate is arranged along the direction of air flow; The top of the inner plate on the heat exchange bottom plate of the water side heat exchange plate (6-2) abuts against the heat exchange bottom plate of the air heat exchange plate (6-1) adjacent to the water side heat exchange plate (6-2); the cavity between the heat exchange bottom plate of the water side heat exchange plate (6-2) and the heat exchange bottom plate of the air heat exchange plate (6-1) is a cooling water flow cavity, and the cooling water flow cavity is used for cooling water flow; in the cooling water flow cavity, the long axis direction of the inner plate is arranged along the direction of cooling water flow; The air flow chamber and the cooling water flow chamber are isolated from each other; The heat exchanger shell is provided with an air inlet, an air outlet, a cooling water inlet and a cooling water outlet. The side where air enters all air flow chambers is connected to the air inlet, the side where air flows out of all air flow chambers is connected to the air outlet, the side where cooling water enters all cooling water flow chambers is connected to the cooling water inlet, and the side where cooling water flows out of all cooling water flow chambers is connected to the cooling water outlet; Condensate guide grooves (6-1-2) are provided on both sides of each row of inner plates on the heat exchange bottom plate of the air heat exchange plate (6-1), and condensate converging grooves (6-1-3) are provided on the heat exchange bottom plate of the air heat exchange plate (6-1) on the air outlet side of the air flow cavity, and the ends of all condensate guide grooves (6-1-2) located on the air outlet side of the air flow cavity on the heat exchange bottom plate of the air heat exchange plate (6-1) are connected to the condensate converging grooves (6-1-3), and the condensate converging grooves (6-1-3) are used to guide the converged condensate water to the outside of the heat exchanger (6); When the air temperature at the air inlet end of the compressor (1) is reduced to a preset range through the heat exchanger (6), condensed water generated by the air cooling is collected through the condensed water guide groove (6-1-2) and then merged into the condensed water confluence groove (6-1-3), and the merged condensed water is guided to the outside of the heat exchanger (6) through the condensed water confluence groove (6-1-3).

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