Condenser steam injection vacuum system and method

Abstract

The invention provides a condenser steam injection vacuum system and method. The condenser steam injection vacuum system comprises a vacuum pump system, a condensing main pipe connected with the vacuum pump system and a condenser steam injection mixing heat exchange vacuum system. The condenser steam injection mixing heat exchange vacuum system is connected to the vacuum pump system in parallel through a condensation main pipe, and the vacuum pump system and the condenser steam injection mixing heat exchange vacuum system achieve unit vacuum through a preset vacuum strategy. According to the scheme, the working efficiency of the steam turbine can be optimized, power generation coal consumption is reduced, and annual benefits are improved.

Description

Technical Field

[0001] This document relates to the field of condenser technology, and more particularly to a condenser steam injection vacuum system and method. Background Art

[0002] In the prior art, most of the vacuum pumping equipment used for condensing steam turbine generator sets is a water ring vacuum pump. When designing and selecting a water ring vacuum pump, quick start and maximum allowable leakage are used as the selection principles. When the unit is operating normally, the vacuum pump has a large margin to maintain the system vacuum and the power configuration is too large. When the condenser works under the normal design back pressure, due to the suction characteristics of the water ring vacuum pump, as the vacuum pump inlet pressure decreases, its suction capacity drops sharply, resulting in low actual operating efficiency of the water ring vacuum pump. Moreover, the performance and output of the water ring vacuum pump are subject to the working water temperature. When the working water temperature is high in summer, the air extraction capacity of the water ring vacuum pump drops sharply, and there are problems such as work output but no output. This type of vacuum pump has a high power consumption when it is running for a long time, and the condenser vacuum maintained in summer is low, which is not conducive to optimizing the efficiency of the steam turbine, thereby affecting the coal consumption for power generation. In addition, in the high vacuum stage, the water ring vacuum pump is prone to cavitation, which leads to increased vibration, louder noise, and easy damage to the impeller, which directly affects the operating stability of the unit. Summary of the invention

[0003] The embodiment of the present invention provides a condenser steam jet vacuum system and method, which solves the problems of serious reduction in steam extraction capacity and severe cavitation of the water ring pump in summer, and solves the problem that the condenser vacuum system is always in a high vacuum range.

[0004] According to an embodiment of the present invention, a condenser steam injection vacuum system is provided, comprising:

[0005] A vacuum pump system, a condensing main pipe connected to the vacuum pump system, and a condenser steam jet mixing heat exchange vacuum system;

[0006] The condenser steam jet mixed heat exchange vacuum system is connected to the vacuum pump system through the condensing main pipe, and the vacuum pump system and the condenser steam jet mixed heat exchange vacuum system realize unit vacuum through a preset vacuum strategy.

[0007] According to an embodiment of the present invention, a condenser steam injection vacuum method is provided, comprising:

[0008] Connect the condenser steam jet mixed heat exchange vacuum system in parallel to the busbar connected to the vacuum pump system;

[0009] In response to different operating states of the unit, a preset vacuum mechanism is used to maintain the vacuum state of the unit.

[0010] By using the vacuum pump system in the embodiment of the present invention in conjunction with the condenser steam jet mixed heat exchange vacuum system, the problems of serious reduction in steam extraction capacity and serious cavitation of the original water ring pump in summer are avoided, and at the same time, the modified condenser vacuum system is always in a high vacuum range, thereby optimizing the turbine work efficiency, saving power generation coal consumption, and the system runs smoothly, safely and reliably. If this part of the benefit is taken into account, the annual energy saving benefit will be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate one or more embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0012] Figure 1 A schematic diagram of a condenser steam jet vacuum system according to an embodiment of the present invention;

[0013] Figure 2 A schematic diagram of a steam jet pump according to an embodiment of the present invention;

[0014] Figure 3 A schematic diagram of the suction volume of various vacuum devices according to an embodiment of the present invention as the pressure changes;

[0015] Figure 4 A flow chart of a condenser steam jet vacuum method according to an embodiment of the present invention; Description of the drawings:

[0017] 1. Head chamber; 2. Power nozzle; 3. Inlet cone; 4. Throat mixing nozzle; 5. Diffuser. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the following will be combined with the drawings in one or more embodiments of this specification to clearly and completely describe the technical solutions in one or more embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this document.

[0019] At present, the vacuum equipment widely used in condenser steam turbine generator sets at home and abroad is mainly water ring vacuum pumps, which are designed with the principle of rapid vacuum establishment and maximum air leakage. With the in-depth treatment of unit leakage, the vacuum tightness has basically reached an excellent level, generally less than 200Pa / min, and some units have a vacuum tightness of less than 100Pa / min. Therefore, the existing water ring vacuum pump has a large design margin for air extraction during normal operation, and has a large space for energy saving and consumption reduction.

[0020] When the condenser works under normal design back pressure, due to the suction characteristics of the water ring vacuum pump, as the vacuum pump inlet pressure decreases, its suction capacity drops sharply; while the suction performance of the condenser steam jet vacuum system can remain basically unchanged.

[0021] System Example

[0022] According to an embodiment of the present invention, a condenser steam injection vacuum system is provided. Figure 1 Schematic diagram of the condenser steam jet vacuum system according to an embodiment of the present invention. Figure 1 As shown, the condenser steam jet vacuum system of the embodiment of the present invention specifically includes:

[0023] A vacuum pump system, a condensing main pipe connected to the vacuum pump system, and a condenser steam jet mixing heat exchange vacuum system;

[0024] The condenser steam jet mixed heat exchange vacuum system is connected to the vacuum pump system through the condensing main pipe, and the vacuum pump system and the condenser steam jet mixed heat exchange vacuum system realize the unit vacuum through a preset vacuum strategy. The vacuum pump system in the embodiment of the present invention includes two water ring vacuum pumps.

[0025] The condenser steam jet mixed heat exchange vacuum system in the embodiment of the present invention comprises: a primary steam jet vacuum system, a secondary steam jet vacuum system, a tubular heat exchanger and a hot well. The primary steam jet vacuum system and the secondary steam jet vacuum system are both composed of a steam jet pump, such as Figure 2 The schematic diagram of the steam jet pump according to the embodiment of the present invention is shown. Figure 2 It can be seen that the steam jet pump of the embodiment of the present invention includes: a head chamber, a power nozzle, an inlet cone part, a throat mixing nozzle and a diffuser. The head chamber is provided with a power steam inlet and a condenser gas inlet respectively, a power nozzle is arranged at the power steam inlet, and the power nozzle and the jet pipe are located on the same horizontal line. The steam jet uses steam as a power medium, generates a supersonic jet through the power nozzle, generates a vacuum in the head chamber, and extracts the mixture in the condenser.

[0026] The working principle of the condenser steam injection mixed heat exchange vacuum system in the embodiment of the present invention is:

[0027] The motive steam passes through the first-stage steam jet pump, which draws in and accelerates the motive steam through the negative pressure principle to form a high-speed steam flow; after passing through the first-stage steam jet pump, the high-speed steam flow enters the second-stage steam jet pump for further acceleration and compression; after the steam is compressed in the second-stage steam jet pump, it enters the tubular heat exchanger for heat exchange with cooling water, and the condensed water generated by the heat exchange is recovered through the hot well.

[0028] The vacuum pump system and the condenser steam jet mixed heat exchange vacuum system realize the unit vacuum through a preset vacuum strategy, specifically including:

[0029] During the unit startup, maintenance and failure stages, a vacuum pump system is used to maintain the unit vacuum;

[0030] During the stable operation stage of the unit, the unit vacuum is maintained by the steam jet mixed heat exchange vacuum system, and the vacuum pump system is on standby.

[0031] The solution of the embodiment of the present invention does not change the equipment and functions of the original vacuum system, but only connects the condenser steam jet mixed heat exchange vacuum system to the original vacuum main pipe. The details are as follows:

[0032] Install a first-stage steam jet vacuum system on the condensate main pipe;

[0033] The steam and gas mixture after heat exchange is collected in one place and extracted by the second-stage steam jet vacuum system;

[0034] The condensed water after heat exchange is returned to the hot well for recovery;

[0035] The steam jet pump uses auxiliary steam or superheated steam from four extractions as motive steam;

[0036] The tubular heat exchanger uses circulating water as the cooling water source.

[0037] During the start-up and vacuum establishment of the unit, the original vacuum pumping equipment is used to quickly start the vacuum; during the stable operation, the condenser steam injection mixed heat exchange vacuum system is put into operation, and the steam injection mixed heat exchange vacuum system is used to maintain and improve the unit vacuum. The two water ring vacuum pumps of the original vacuum pumping system are on standby. When the system is under maintenance or fails, it can be freely switched to the original vacuum pumping equipment to maintain the vacuum. After the implementation of this plan, there is no adverse effect on the safety of the original system of the power plant, and the stability, safety and reliability of the unit are improved. Figure 3 Schematic diagram of the suction volume of various vacuum devices according to the embodiment of the present invention as the pressure changes; Figure 3It can be seen that when the condenser vacuum is close to the ultimate vacuum, the suction capacity of the two-stage water ring vacuum pump and the single-stage water ring vacuum pump is significantly reduced compared with the suction capacity of the steam jet pump, and the performance is attenuated. When the inlet vacuum value of the steam jet pump is lower than the ultimate vacuum value, the suction capacity of the steam jet pump remains basically unchanged and the performance is stable.

[0038] Since the steam jet pump has a strong suction capacity and can meet the normal operation requirements of the condenser, and the amount of uncondensed steam and non-condensable gas after the steam at the outlet of the steam jet pump is condensed by the heat exchanger is small, in summer, as the ambient temperature rises, the condenser steam jet mixed heat exchange vacuum system is not affected by the ambient temperature, and no cavitation will occur during operation. Under the same working conditions, the vacuum degree of the unit can be significantly improved compared with the water ring vacuum pump. The system uses circulating water as the cooling water source. According to the projects of the condenser steam jet mixed heat exchange vacuum system that have been put into operation, this system operates safely and reliably. Automatic and disturbance-free switching can be achieved when the system fails. This system does not have any rotating equipment, so the system operates safely, with very little maintenance, no wearing parts, and the maintenance cycle is 2 to 3 times that of a general vacuum system with rotating equipment. After the implementation of this plan, there is no adverse effect on the safety of the original system of the power plant. Since there is no rotating equipment in this system, the system operates more stably and reliably. The modified condenser steam jet mixed heat exchange vacuum system is measured by the following technical indicators:

[0039] (1) Power saving rate 100%.

[0040] (2) The average annual vacuum level of the unit is increased by about 0.2-0.5 kPa.

[0041] (3) Based on the conservative estimate of increasing the vacuum value by 0.2 kPa and the annual utilization of the vacuum unit of 4100 h, the transformation can bring an economic benefit of more than 900,000 yuan per year. After a one-time investment, it can be recovered in about 2.8 years.

[0042] (4) No rotation and no maintenance.

[0043] (5) The system runs smoothly, safely and reliably.

[0044] Table 1 Power plant related parameters

[0045]

[0046] Table 2 Economic analysis

[0047]

[0048] According to Table 1 and Table 2, the economic analysis is as follows:

[0049] 1. The benefits of reduced coal consumption corresponding to increased vacuum (the average annual increase in vacuum is calculated based on a conservative estimate of 0.2 kPa, and the annual utilization hours are 4,100)

[0050] 0.2×(350×103)×4100×(3.2×10-6)×750=688,800 yuan

[0051] 2. Solve the problem of cavitation and extend the life of the impeller, saving spare parts and labor costs: 10,000 yuan / year

[0052] 3. Power saving: (After the transformation, the vacuum pump is changed from one operating and one standby to two standby, saving the power consumption of one vacuum pump. The rated power of the motor is 110kW)

[0053] 110×4100×0.4=180,400 yuan

[0054] 4. Power steam condensation benefits:

[0055] Auxiliary steam consumption of the system after transformation (using auxiliary steam as power injection exhaust steam, the system consumes about 800kg / h of auxiliary steam, corresponding to 800kg / h of power steam condensed back to the condenser hot well water)

[0056] Power steam condensation enthalpy (pressure 5.1 kPa (a), temperature 33.23 ° C): 139.24 kJ / kg.

[0057] 139.24kJ / kg×800kg / h×4100h=456,707,200kJ

[0058] Converted to standard coal: 456,707,200 kJ ÷ 29260 kJ / kg = 15.6 tons

[0059] 15.6 tons x 750 yuan / ton = 11,700 yuan

[0060] Power steam consumption:

[0061] Power steam enthalpy (pressure 0.6MPa, temperature 250℃): 2952.72kJ / kg.

[0062] 2952.72kJ / kg×800kg / h×4100h=9,684,921,600kJ

[0063] Converted to standard coal: 9,684,921,600 kJ ÷ 29260 kJ / kg = 330.9 tons

[0064] 330.9 tons x 750 yuan / ton = 248,200 yuan

[0065] 5. Annual direct economic benefits after transformation:

[0066] (68.88+1+18.04+1.17)-24.82=642,700 yuan

[0067] 6. Analysis and calculation of indicators such as return on investment

[0068] Total project investment: RMB 2.5 million (including DCS hardware and configuration)

[0069] The investment payback period is: 250÷64.27=3.8 years.

[0070] By adopting the embodiment of the present invention, the following beneficial effects can be achieved: not only can the serious decline in the steam extraction capacity and serious cavitation of the raw water ring pump in summer be avoided, but also the vacuum system of the modified condenser can be ensured to be always in a high vacuum range, thereby optimizing the work efficiency of the steam turbine, saving the coal consumption for power generation, and the system running smoothly, safely and reliably. If this part of the benefit is taken into account, the annual energy saving benefit will be further improved.

[0071] Method Embodiment

[0072] According to the present invention, a condenser steam jet vacuum method is provided. Figure 4 Flow chart of the condenser steam jet vacuum method according to an embodiment of the present invention. Figure 4 As shown, the condenser steam injection vacuum method of the embodiment of the present invention specifically includes:

[0073] S1. Connect the condenser steam jet mixed heat exchange vacuum system in parallel to the busbar connected to the vacuum pump system;

[0074] S2. In response to different operating states of the unit, a preset vacuum mechanism is used to maintain the vacuum state of the unit.

[0075] The method of maintaining the vacuum state of the unit by using a preset vacuum mechanism in response to different operating states of the unit specifically includes:

[0076] During the unit startup, maintenance and failure stages, a vacuum pump system is used to maintain the unit vacuum;

[0077] During the stable operation stage of the unit, the unit vacuum is maintained by the steam jet mixed heat exchange vacuum system, and the vacuum pump system is on standby.

[0078] The vacuum pump system includes two water ring vacuum pumps.

[0079] The condenser jet mixed heat exchange vacuum system comprises: a primary steam jet vacuum system, a secondary steam jet vacuum system, a tubular heat exchanger and a hot well.

[0080] The working principle of the steam jet mixed heat exchange vacuum system specifically includes:

[0081] The motive steam passes through the first-stage steam jet pump, which draws in and accelerates the motive steam through the negative pressure principle to form a high-speed steam flow; after passing through the first-stage steam jet pump, the high-speed steam flow enters the second-stage steam jet pump for further acceleration and compression; after the steam is compressed in the second-stage steam jet pump, it enters the tubular heat exchanger for heat exchange with cooling water, and the condensed water generated by the heat exchange is recovered through the hot well.

[0082] The command, when executed, implements the steps of the above-mentioned method for modeling the aerodynamic efficiency of two-body separated control surfaces.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A condenser steam jet vacuum system, characterized in that include: A vacuum pump system, a condensation main pipe connected to the vacuum pump system, and a condenser steam jet mixing heat exchange vacuum system; The condenser steam jet mixed heat exchange vacuum system is connected to the vacuum pump system through the condensing main pipe, and the vacuum pump system and the condenser steam jet mixed heat exchange vacuum system realize unit vacuum through a preset vacuum strategy.

2. The system according to claim 1, characterized in that The vacuum pump system and the condenser steam jet mixed heat exchange vacuum system realize the unit vacuum through a preset vacuum strategy, specifically including: During the unit startup, maintenance and failure stages, a vacuum pump system is used to maintain the unit vacuum; During the stable operation stage of the unit, the unit vacuum is maintained by the steam jet mixed heat exchange vacuum system, and the vacuum pump system is on standby.

3. The system according to claim 1, characterized in that The vacuum pump system comprises two water ring vacuum pumps.

4. The system according to claim 1, characterized in that The condenser steam jet mixed heat exchange vacuum system comprises: a primary steam jet vacuum system, a secondary steam jet vacuum system, a tubular heat exchanger and a hot well.

5. The system according to claim 1, characterized in that The condenser steam jet mixed heat exchange vacuum system is specifically used for: The motive steam passes through the first-stage steam jet pump, which draws in and accelerates the motive steam through the negative pressure principle to form a high-speed steam flow; after passing through the first-stage steam jet pump, the high-speed steam flow enters the second-stage steam jet pump for further acceleration and compression; after the steam is compressed in the second-stage steam jet pump, it enters the tubular heat exchanger for heat exchange with cooling water, and the condensed water generated by the heat exchange is recovered through the hot well.

6. A condenser steam jet vacuum method, characterized in that include: Connect the condenser steam jet mixed heat exchange vacuum system in parallel to the busbar connected to the vacuum pump system; In response to different operating states of the unit, a preset vacuum mechanism is used to maintain the vacuum state of the unit.

7. The method according to claim 6, characterized in that The method of maintaining the vacuum state of the unit by using a preset vacuum mechanism in response to different operating states of the unit specifically includes: During the unit startup, maintenance and failure stages, a vacuum pump system is used to maintain the unit vacuum; During the stable operation stage of the unit, the unit vacuum is maintained by the steam jet mixed heat exchange vacuum system, and the vacuum pump system is on standby.

8. The method according to claim 6, characterized in that The vacuum pump system includes two water ring vacuum pumps.

9. The method according to claim 6, characterized in that The condenser jet mixed heat exchange vacuum system comprises: a primary steam jet vacuum system, a secondary steam jet vacuum system, a tubular heat exchanger and a hot well.

10. The method according to claim 7, characterized in that The working principle of the steam jet mixed heat exchange vacuum system specifically includes: The motive steam passes through the first-stage steam jet pump, which draws in and accelerates the motive steam through the negative pressure principle to form a high-speed steam flow; after passing through the first-stage steam jet pump, the high-speed steam flow enters the second-stage steam jet pump for further acceleration and compression; after the steam is compressed in the second-stage steam jet pump, it enters the tubular heat exchanger for heat exchange with cooling water, and the condensed water generated by the heat exchange is recovered through the hot well.

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