Four-stage cascade heating and heat supply system of thermal power generating unit

Abstract

The utility model provides a thermal power generating unit four-stage cascade heating and heat supply system. The thermal power generating unit four-stage cascade heating and heat supply system comprises a high-back-pressure condenser, a steam increasing machine condenser and a four-stage heating channel formed by parallel heat supply network heaters which are sequentially connected in series. The steam increasing machine condenser comprises a front half part and a rear half part which are connected in series; the first-stage heat exchange tube bundle is arranged on the front half part of the steam increasing machine condenser, the second-stage heat exchange tube bundle is arranged on the rear half part of the steam increasing machine condenser, and the first steam increasing machine and the second steam increasing machine are arranged in parallel. And the outlet of the condenser is respectively connected with the front half throat part and the rear half throat part of the steam increasing machine condenser. According to the scheme, the comprehensive performance of the heat supply system of the thermal power generating unit is remarkably improved through the cooperative operation of the four-stage cascade heating system and the double steam increasing engines and the multi-unit combined supply design.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of thermal power generating unit heating technology, specifically relates to a four-stage cascade heating heating system based on high back pressure unit and steam augmenter cooperation. BACKGROUND

[0002] In northern areas, thermal power generating unit heating reconstruction has become a general trend, and some units are even directly designed as heating units. In the early stage, unit heating mainly adopts the mode of steam extraction driving heat network heater. With the development of technology, many power plants begin to adopt high back pressure heating technology, covering air-cooled units and wet-cooled units.

[0003] In recent years, the generalized high multiple pressure technology based on steam augmenter or ejector has been gradually applied. This technology is further expanded to a three-stage cascade heating system of high back pressure + steam augmenter + heat network heater on the basis of the two-stage cascade heating system of high back pressure heating network heater. This improvement further improves the utilization rate of exhaust steam and increases the consumption of exhaust steam of the unit on the basis of the original high back pressure, effectively reduces the overall heating coal consumption, and has significant energy-saving advantages.

[0004] However, the current domestic three-stage heating system of high back pressure + steam augmenter + heat network heater still has some problems to be solved. Although the utilization amount of exhaust steam of this system is increased compared with pure high back pressure heating under general operating conditions, from the perspective of improving energy utilization efficiency, the utilization amount of exhaust steam still has room for further improvement.

[0005] At the same time, with the advancement of power marketization reform, heating units are no longer limited to the traditional "heat-determined power operation" mode and also begin to participate in peak shaving. In the low load stage of heating unit peak shaving, the exhaust pressure of a single unit will be reduced, which has a negative impact on the efficiency of the steam augmenter, and further affects the performance of the entire heating system.

[0006] In addition, although the three-stage cascade heating system of high back pressure + steam augmenter + heat network heater of a single unit has improved flexibility compared with the two-stage cascade heating system of high back pressure + heat network heater, from the perspective of adapting to complex and variable operating conditions and further optimizing system performance, the system still has a large space for improvement in flexibility. In summary, a new technical solution is urgently needed to solve the above problems to further improve the performance and adaptability of the heating system. INVENTION CONTENTS

[0007] In view of the defects of the prior art, the utility model provides a multi-heat network circulating water pipeline air-cooled unit high back pressure cascade heating integrated condenser, which combines traditional multiple condensers into a single device through structural innovation, solving the problems of complex system, high investment and low efficiency.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is:

[0009] A four-stage cascade heating system for a thermal power unit, comprising:

[0010] A four-stage heating channel formed by a high-back-pressure condenser, a steam-increasing condenser and parallelly connected heat network heaters;

[0011] A first-stage heat exchange tube bundle arranged on the front half of the steam-increasing condenser,

[0012] A second-stage heat exchange tube bundle arranged on the rear half of the steam-increasing condenser,

[0013] A first steam-increasing device and a second steam-increasing device arranged in parallel, with their outlets connected to the throat of the front half and the throat of the rear half of the steam-increasing condenser, respectively.

[0014] Further, the front half comprises a front water chamber of the steam-increasing condenser, and the rear half comprises a rear water chamber of the steam-increasing condenser, with the front water chamber and the rear water chamber connected in series through a middle water chamber.

[0015] Further, the front half comprises a first-stage drain heat well, and the rear half comprises a second-stage drain heat well, with the drains collected to the heat well of the high-back-pressure condenser through the second-stage drain heat well and the first-stage drain heat well.

[0016] Further, the heat network heater comprises a first heat network heater and a second heat network heater arranged in parallel, for heating steam from a steam inlet electric gate of the first heat network heater and a steam inlet electric gate of the second heat network heater, respectively.

[0017] Further,

[0018] The first-stage drain heat well is connected to a condensate outlet of the front half.

[0019] The second-stage drain heat well is connected to drains of the rear half and the heat network heater.

[0020] Further, the system further comprises an independent vacuum pumping system, including two water ring vacuum pumps, a vacuum main pipe and a PLC controller.

[0021] Compared with the prior art, the present application has the following beneficial technical effects:

[0022] The present technical scheme significantly improves the comprehensive performance of the heating system of the thermal power unit through the four-stage cascade heating system, the cooperative operation of the double steam-increasing devices and the multi-unit combined heat and power design. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and the ordinary skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0024] Figure 1 It is a structural schematic diagram of a four-stage cascade heating heat supply system of a thermal power generating unit. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the ordinary skilled in the art without any creative effort are within the protection scope of the present application.

[0026] The present application is a four-stage cascade heating heat supply system of a thermal power generating unit, comprising:

[0027] A four-stage heating channel composed of a high-back-pressure condenser 20, a steam-increasing condenser and parallelly connected heat network heaters 35, 36 connected in series; the steam-increasing condenser comprises a front half and a rear half connected in series;

[0028] A first-stage heat exchange tube bundle 12, which is arranged on the front half 9 of the steam-increasing condenser,

[0029] A second-stage heat exchange tube bundle 13, which is arranged on the rear half 8 of the steam-increasing condenser,

[0030] A first steam-increasing device 5 and a second steam-increasing device 6 arranged in parallel, the outlets of which are connected to the throat 7 of the front half and the throat 8 of the rear half of the steam-increasing condenser respectively.

[0031] In the present application, the front half comprises a front water chamber 9 of the steam-increasing condenser, the rear half comprises a rear water chamber 10 of the steam-increasing condenser, and the front water chamber 9 of the steam-increasing condenser and the rear water chamber 10 of the steam-increasing condenser are connected in series through a middle water chamber 11.

[0032] In the present application, the front half comprises a first-stage drain heat well 14, and the rear half comprises a second-stage drain heat well 15, and the drains are gathered to the high-back-pressure condenser heat well 21 through the second-stage drain heat well 15 and the first-stage drain heat well 14.

[0033] In the present application, the heat network heater 35, 36 includes a first heat network heater 35 and a second heat network heater 36 connected in parallel, respectively for heating steam from the first heat network heater steam inlet electric door 26 and the second heat network heater steam inlet electric door 27.

[0034] In the present application,

[0035] The first stage hydrophobic heat well 14 is connected to the condensate outlet of the front half 9;

[0036] The second stage hydrophobic heat well 15 is connected to the rear half 8 and the heat network heater hydrophobic.

[0037] In the present application, an independent vacuum pumping system is also included, including two water ring vacuum pumps, a vacuum main pipe and a PLC controller.

[0038] Referring to Figure 1 , the working principle of the present application is further introduced:

[0039] I. Heat network circulating water system

[0040] First stage heating

[0041] The heat network circulating water backwater enters the high back pressure condenser 20 heat exchange tube bundle for preliminary heating through the heat network circulating water backwater electric butterfly valve 22, and then flows out of the first stage heating system through the high back pressure condenser outlet water electric butterfly valve 23.

[0042] Second stage heating

[0043] The heat network circulating water after preliminary heating flows into the front water chamber 9 of the steam augmenter condenser, and after distribution, uniformly enters the first stage heat exchange tube bundle 12 of the steam augmenter condenser for second stage heating.

[0044] Third stage heating

[0045] The heat network circulating water after completing second stage heating enters the middle water chamber 11 of the steam augmenter condenser, mixes, and is uniformly distributed to the second stage heat exchange tube bundle 13 of the steam augmenter condenser for third stage heating.

[0046] Fourth stage heating

[0047] The heat network circulating water after completing third stage heating enters the heat network circulating water pump 25 through the rear water chamber 10 of the steam augmenter condenser, is boosted in pressure, and is divided into two paths:

[0048] One path enters the first heat network heater 35 through the first heat network heater water inlet electric door 28;

[0049] The other path enters the second heat network heater 36 through the second heat network heater water inlet electric door 29.

[0050] The circulating water of the heat supply network completes the fourth stage heating in the heat supply network heater, and is collected by the first heat supply network heater outlet electric door 30 and the second heat supply network heater outlet electric door 31 to be output as water supply.

[0051] II. Heating steam system

[0052] High back pressure heat supply steam flow

[0053] The exhaust steam of the steam turbine enters the high back pressure condenser throat 19 through the high back pressure condenser inlet electric door 18, and is cooled and condensed to release the latent heat of vaporization.

[0054] Power steam supply of the steam augmenter

[0055] The first steam augmenter 5: the power steam comes from the middle exhaust steam main pipe, the injected fluid enters through the first steam augmenter exhaust inlet electric door 3, the mixed compressed fluid enters the front half of the steam augmenter condenser throat 7, and flows through the front half of the heat exchange tube bundle 12 to be cooled and liquefied.

[0056] The second steam augmenter 6: the power steam comes from the same source, the injected fluid enters through the second steam augmenter exhaust inlet electric door 4, the mixed compressed fluid enters the rear half of the steam augmenter condenser throat 8, and flows through the rear half of the heat exchange tube bundle 13 to be cooled and liquefied.

[0057] Heat supply network heater steam control

[0058] The heating steam of the first heat supply network heater 35 is supplied through the first heat supply network heater inlet electric door 26;

[0059] The heating steam of the second heat supply network heater 36 is supplied through the second heat supply network heater inlet electric door 27;

[0060] The steam of the middle exhaust steam main pipe is supplied through the #1 machine middle exhaust steam hydraulic control valve 37 and the #2 machine middle exhaust steam hydraulic control valve 38, and is distributed to each heating unit through the first steam augmenter power steam electric door 1, the second steam augmenter power steam electric door 4, and the heat supply network heater inlet electric total door 24 in sequence.

[0061] III. Drainage system

[0062] Heat supply network heater drainage recovery

[0063] The first heat supply network heater drainage and the second heat supply network heater drainage are mixed after passing through the first heat supply network heater drainage regulating valve 32 and the second heat supply network heater drainage regulating valve 33, and then enter the heat supply network heater drainage main pipe;

[0064] The mixed drainage is self-flowed to the second drainage well 15 of the steam augmenter condenser from the drainage main pipe, and is combined with the condensed water after the liquefaction of the rear half of the steam augmenter condenser (the second compressed fluid).

[0065] Drainage step-by-step collection

[0066] The second hydrophobic hot well hydrophobic through hydrophobic pipeline 17 from the steam generator condenser first hydrophobic hot well 14, with the first half (the first compressed fluid) liquefied condensate, heat network heater hydrophobic further mixed;

[0067] The first hydrophobic hot well hydrophobic through hydrophobic pipeline 16 from the high back pressure condenser hot well 21, with the steam turbine exhaust condensate water to form a heat network system condensate.

[0068] Condensate shunt control

[0069] The heat network system condensate is divided into two ways:

[0070] One way through the high back pressure condenser hydrophobic to the #1 machine condenser hot well electric regulating valve 39 into the #1 machine condensate system;

[0071] The other way through the high back pressure condenser hydrophobic to the #2 machine condenser hot well electric regulating valve 40 into the #2 machine condensate system.

[0072] Four, vacuum system

[0073] The system is configured to extract the vacuum system, for pumping high back pressure condenser, steam generator condenser (including the first stage 12 and the second stage 13 heat exchange tube bundle area) accumulated in the non-condensable gas. According to the original unit configuration, the vacuum system can take the following two ways:

[0074] Independent configuration: add a dedicated vacuum pump set, independent control of vacuum;

[0075] Access to the main pipe of the vacuum system: use the original unit vacuum system balance, through the branch pipe access.

[0076] Finally, it should be noted that: the above examples are used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A four-stage cascade heating system for thermal power units, characterized in that, include: A four-stage heating channel consisting of a high back-pressure condenser (20), a turbocharger condenser, and a parallel heating network heater connected in series; the turbocharger condenser includes a front half and a rear half connected in series. The first-stage heat exchange tube bundle (12) is installed on the front half of the condenser of the steam turbine. The second-stage heat exchange tube bundle (13) is installed on the rear half of the condenser of the steam turbine. The first steam turbine (5) and the second steam turbine (6) are set in parallel, and their outlets are respectively connected to the throat of the front half (7) and the throat of the rear half (8) of the steam turbine condenser.

2. The system according to claim 1, characterized in that, The first half includes the front water chamber (9) of the condenser of the steam turbine, and the second half includes the rear water chamber (10) of the condenser of the steam turbine. The front water chamber (9) and the rear water chamber (10) of the condenser of the steam turbine are connected in series through the middle water chamber (11).

3. The system according to claim 1, characterized in that, The first half includes a first-stage condensate drain well (14), and the second half includes a second-stage condensate drain well (15). Drainage is collected through the second-stage condensate drain well (15) and the first-stage condensate drain well (14) to the high back pressure condenser drain well (21).

4. The system according to claim 1, characterized in that, The parallel heating network heater includes a first heating network heater (35) and a second heating network heater (36) connected in parallel, which are used to heat steam from the first heating network heater inlet electric valve (26) and the second heating network heater inlet electric valve (27), respectively.

5. The system according to claim 1, characterized in that, The first-stage hydrophobic heat well (14) is connected to the condensate outlet of the first half; The second-stage drainage hot well (15) connects to the rear half of the heat network heater drainage.

6. The system according to claim 1, characterized in that: It also includes an independent vacuum system, consisting of two water ring vacuum pumps, a vacuum header, and a PLC controller.

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