A waste heat power generation system and control method based on a low-pressure heater

Abstract

The present invention relates to the technical field of waste heat recovery, and specifically discloses a waste heat power generation system and a control method based on a low-pressure heater, including a kiln tail SP boiler, a kiln head AQC boiler connected to the kiln tail SP boiler, and a steam turbine house; the steam turbine house includes a steam turbine connected to the kiln head AQC boiler, a generator connected to the steam turbine, a condenser assembly connected to the steam turbine, a condensate pump connected to the condenser assembly, a gland heater, a low-pressure heater, a deaerator, and a feed water pump; the low-pressure heater is respectively connected to the low-pressure steam outlet of the kiln head AQC boiler and the condenser assembly, and the feed water pump is connected to the kiln head AQC boiler. The present invention uses the low-pressure heater to heat the condensate water, improves the temperature of the boiler feed water, reduces the load of the boiler economizer, that is, reduces the usage amount of the heat exchange tubes of the boiler economizer, and reduces the cost of the boiler economizer; improves the deaeration effect of the deaerator, reduces the oxygen corrosion of the boiler heat exchange pipes, and improves the service life of the boiler.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery, and more specifically, to a waste heat power generation system and a control method based on a low-pressure heater. Background Art

[0002] The cement production process consumes a large amount of fossil energy and electric energy. At the same time, there is a large amount of energy waste in the cement production system. In order to reduce energy consumption and solve the power supply problem, the cement production process is equipped with a waste heat power generation system.

[0003] Although the waste heat power generation technology in cement plants has been very mature, how to better recover and utilize the heat wasted in the cement production firing system is still the most concerned issue. The waste heat power generation system in cement plants has gradually developed from a single-pressure system to the existing double-pressure system, which has reduced the flue gas temperature at the outlet of the kiln head boiler in the cement plant to about 90°C and reduced the dust content in the flue gas at the same time.

[0004] The double-pressure system for waste heat power generation in cement plants has many advantages. However, due to the volatility of the cement plant clinker firing process, the waste heat power generation system is not very stable. In particular, the low-pressure steam supply often cannot be supplemented into the steam turbine, and at the same time, condensate is likely to accumulate at the steam supply port, affecting the stable operation and service life of the steam turbine. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a waste heat power generation system and a control method based on a low-pressure heater;

[0006] The solution adopted by the present invention to solve the technical problem is as follows:

[0007] A waste heat power generation system based on a low-pressure heater, including a kiln tail SP boiler connected to a kiln tail preheater, a kiln head AQC boiler connected to the kiln tail SP boiler and a kiln head grate cooler, and a steam turbine house connected to the kiln head AQC boiler;

[0008] The steam turbine house includes a steam turbine connected to the kiln head AQC boiler, a generator connected to the steam turbine, a condensing assembly connected to the steam turbine, a condensate pump connected to the condensing assembly, a gland steam heater, a low-pressure heater, a deaerator, and a feed water pump;

[0009] The condensate pump, the gland steam heater, the low-pressure heater, the deaerator, and the feed water pump are connected in sequence;

[0010] The low-pressure heater is respectively connected to the low-pressure steam outlet of the kiln head AQC boiler and the condensing assembly, and the feed water pump is connected to the kiln head AQC boiler;

[0011] The steam turbine is connected to the high-pressure steam outlet of the kiln head AQC boiler.

[0012] In the present invention, by connecting the low-pressure heater to the low-pressure steam outlet of the AQC boiler at the kiln head, the low-pressure steam is only used to heat the condensed water condensed by the condensing assembly and not for steam turbine power generation; heating the condensed water with the low-pressure heater increases the temperature of the boiler feed water, reduces the load of the economizer of the boiler, that is, reduces the usage amount of the heat exchange tubes of the economizer of the boiler, and reduces the cost of the economizer of the boiler; improves the deaeration effect of the deaerator, reduces the oxygen corrosion of the boiler heat exchange pipes, and increases the service life of the boiler; reduces the gas production amount of the low-pressure evaporation section of the AQC boiler at the kiln head, increases the evaporation amount of the high-pressure section, and improves the operation stability and safety of the steam turbine.

[0013] In some possible implementation manners, it further includes a dust collection system respectively connected to the kiln head grate cooler and the AQC boiler at the kiln head.

[0014] In some possible implementation manners, the dust collection system includes a dust collector respectively connected to the AQC boiler at the kiln head and the kiln head grate cooler, an induced draft fan connected to the output end of the dust collector, and a chimney connected to the induced draft fan; the AQC boiler at the kiln head and the kiln head grate cooler are connected to the input end of the dust collector.

[0015] In some possible implementation manners, a high-pressure induced draft fan is externally connected to the SP boiler at the kiln tail, and the high-pressure induced draft fan is connected to the raw material drying system through a pipeline.

[0016] In some possible implementation manners, a common economizer connected to a feed water pump, a low-pressure steam drum, a low-pressure evaporator, a low-pressure superheater connected to the low-pressure evaporator, a first high-pressure economizer, a first high-pressure steam drum, a first high-pressure evaporator, and a first high-pressure superheater are arranged in the AQC boiler at the kiln head; the low-pressure steam drum, the low-pressure evaporator, and the low-pressure superheater are connected in sequence;

[0017] The first high-pressure steam drum, the first high-pressure evaporator, and the first high-pressure superheater are connected in sequence;

[0018] The common economizer is respectively connected to the low-pressure steam drum, the first high-pressure economizer, and the SP boiler at the kiln tail.

[0019] In some possible implementation manners, a second high-pressure economizer, a second high-pressure steam drum, a second high-pressure evaporator, and a second high-pressure superheater are arranged in sequence in the SP boiler at the kiln tail; the second high-pressure economizer is connected to the common economizer; the second high-pressure superheater is connected to the first high-pressure superheater; a common superheater for respectively connecting the second high-pressure superheater and the first high-pressure superheater is arranged in the AQC boiler at the kiln head, and the common superheater is connected to the steam turbine.

[0020] In some possible implementation manners, the condensing assembly includes a condenser and a water circulation system used in cooperation with the condenser; the condenser is connected to the low-pressure heater and a condensate pump.

[0021] In some possible embodiments, there are two groups of the low-pressure heaters, which are arranged in series.

[0022] A control method for a waste heat power generation system based on a low-pressure heater as described above specifically includes the following steps:

[0023] The flue gas at the kiln tail enters the kiln tail SP boiler through the kiln tail preheater to heat the feed water to generate high-pressure steam II, which is then transported to the kiln head AQC boiler for further heating;

[0024] The hot flue gas extracted from the kiln head grate cooler enters the kiln head AQC boiler to heat the feed water, generating low-pressure steam and high-pressure steam I;

[0025] The low-pressure steam is sent to the low-pressure heater to heat the condensed water condensed by the condensing assembly. The condensed water is transported to the kiln head AQC boiler through the feed water pump. After the high-pressure steam I is aggregated with the high-pressure steam, it is reheated to generate high-pressure steam, which is transported to the steam turbine inlet in the steam turbine house for power generation.

[0026] In some possible embodiments, the condensed water sequentially passes through the condensate pump, shaft seal heater, low-pressure heater, deaerator, and feed water pump and then is transported to the common economizer. The common economizer transports the condensed water to the high-pressure economizer II of the kiln tail SP boiler, the low-pressure steam drum of the kiln head AQC boiler, and the high-pressure economizer I of the kiln head AQC boiler respectively;

[0027] Among them, after part of the condensed water entering the high-pressure economizer II of the kiln tail SP boiler is heat-exchanged, it passes through the high-pressure evaporator II and high-pressure superheater II to generate high-pressure steam II, which enters the common superheater of the kiln head AQC boiler;

[0028] After part of the condensed water entering the high-pressure economizer I of the kiln head AQC boiler is heat-exchanged, it passes through the high-pressure evaporator I and high-pressure superheater I to generate high-pressure steam I, which enters the common superheater of the kiln head AQC boiler. The high-pressure steam I is mixed with the high-pressure steam II passing through the high-pressure superheater II. After passing through the common superheater, high-pressure steam is generated and transported to the steam turbine;

[0029] After part of the condensed water entering the kiln head AQC boiler is heat-exchanged, it enters the low-pressure steam drum, passes through the low-pressure evaporator and low-pressure superheater to generate low-pressure steam, which is transported to the low-pressure heater.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The present invention uses a low-pressure heater to heat the condensed water, which increases the temperature of the boiler feed water, reduces the load on the boiler economizer, that is, reduces the usage amount of the heat exchange tubes of the boiler economizer and lowers the cost of the boiler economizer;

[0032] The present invention uses a low-pressure heater to heat the condensate, increasing the temperature of the boiler feed water, enhancing the deaeration effect of the deaerator, reducing the oxygen corrosion of the boiler heat exchange pipes, and increasing the service life of the boiler.

[0033] The present invention reduces the gas production of the low-pressure evaporation section of the AQC boiler at the kiln head; increases the evaporation capacity of the high-pressure section, improving the operational stability and safety of the steam turbine.

[0034] The present invention can be adapted regardless of the winter temperature or the output of the clinker production line in the cement plant. The AQC boiler at the kiln head can adopt a dual-pressure system, improving the waste heat recovery efficiency of the cement plant.

[0035] In the present invention, the steam turbine adopts a single-pressure system, which has a simple structure, is easy to maintain, and has an extended service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram when there is one group of low-pressure heaters in the present invention;

[0037] Figure 2 It is a schematic structural diagram when there are two groups of low-pressure heaters in the present invention;

[0038] Figure 3 It is a schematic connection diagram of the grate cooler at the kiln head, the preheater at the kiln tail, the AQC boiler at the kiln head, and the SP boiler at the kiln tail in the present invention;

[0039] Wherein: 100, grate cooler at the kiln head; 200, preheater at the kiln tail; 300, dust removal system; 1, AQC boiler at the kiln head; 11, common economizer; 12, low-pressure steam drum; 13, low-pressure evaporator; 14, low-pressure superheater; 15, first high-pressure economizer; 16, first high-pressure steam drum; 17, first high-pressure evaporator; 18, first high-pressure superheater; 19, common superheater; 2, SP boiler at the kiln tail; 21, second high-pressure economizer; 22, second high-pressure steam drum; 23, second high-pressure evaporator; 24, second high-pressure superheater; 3, steam turbine; 4, generator; 5, condenser assembly; 6, condensate pump; 7, gland heater; 8, low-pressure heater; 81, first low-pressure heater; 82, second low-pressure heater; 9, deaerator; 10, feed water pump. DETAILED DESCRIPTION OF THE INVENTION

[0040] In the present invention, unless otherwise clearly specified and defined, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two components or the interaction relationship between two components. The "first", "second" and similar words mentioned in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "a" or "one" do not indicate a quantity limitation either, but indicate that there is at least one. In the implementation of this application, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In the description of the embodiments of this application, unless otherwise stated, the meaning of "a plurality" refers to two or more. For example, a plurality of positioning posts means two or more positioning posts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The present invention will be described in detail below.

[0042] As Figures 1 - 3 shown:

[0043] A waste heat power generation system based on a low-pressure heater, which is applied to the waste heat recovery of a cement plant, includes a kiln tail SP boiler 2 connected to a kiln tail preheater 200, a kiln head AQC boiler 1 connected to the kiln tail SP boiler 2 and a kiln head grate cooler 100, and a steam turbine house connected to the kiln head AQC boiler 1;

[0044] The steam turbine house includes a steam turbine 3 connected to the kiln head AQC boiler 1, a generator 4 connected to the steam turbine 3, a condensing assembly 5 connected to the steam turbine 3, a condensate pump 6 connected to the condensing assembly 5, a gland heater 7, a low-pressure heater 8, a deaerator 9, and a feed water pump 10;

[0045] The condensate pump 6, gland heater 7, low-pressure heater 8, deaerator 9, and feed water pump 10 are connected in sequence;

[0046] The low-pressure heater 8 is respectively connected to the low-pressure steam outlet of the kiln head AQC boiler 1 and the condensing assembly 5, and the feed water pump 10 is connected to the kiln head AQC boiler 1;

[0047] The steam turbine 3 is connected to the high-pressure steam outlet of the kiln head AQC boiler 1.

[0048] During use, the hot flue gas with a relatively high temperature extracted by the kiln head grate cooler 100 in the cement firing system enters the kiln head AQC boiler 1, and is discharged to the atmosphere after heat exchange in the kiln head AQC boiler 1;

[0049] The flue gas at the tail of the kiln enters the SP boiler 2 at the tail of the kiln through the outlet of the preheater 200 at the tail of the kiln. After heat exchange in the SP boiler 2 at the tail of the kiln, it is sent to the raw material drying system of the cement plant through a high-temperature induced draft fan;

[0050] The condensed water condensed by the condensing component 5 passes through the condensate pump 6 and the gland heater 7 and is sent to the low-pressure heater 8 for heating and then enters the deaerator 9. After deaeration in the deaerator 9, part of the condensed water enters the AQC boiler 1 at the kiln head through the feed water pump 10, exchanges heat with the hot flue gas to generate low-pressure steam and high-pressure steam I; part of the condensed water will be transported to the SP boiler 2 at the tail of the kiln through the AQC boiler 1 at the kiln head, exchanges heat with the flue gas at the tail of the kiln, and generates high-pressure steam II;

[0051] High-pressure steam II and high-pressure steam I are aggregated and reheated, and enter the steam turbine 3 through the high-pressure steam outlet for power generation; the heat carried by the low-grade waste heat flue gas is converted into high-grade water steam and sent to the steam turbine generator set 4 for power generation;

[0052] The low-pressure steam enters the low-pressure heater 8 through the low-pressure steam outlet. After passing through the low-pressure heater 8, the low-pressure steam heats the condensed water condensed by the condensing component 5, and the low-pressure steam condenses into water after heat exchange. This part of the water will be transported to the condensing component; the condensed water is then transported to the AQC boiler 1 at the kiln head through the feed water pump 10.

[0053] In the present invention, by connecting the low-pressure heater 8 with the low-pressure steam outlet of the AQC boiler 1 at the kiln head, the low-pressure steam is only used to heat the condensed water condensed by the condensing component 5 and is not used for power generation by the steam turbine 3; using the low-pressure heater 8 to heat the condensed water increases the temperature of the feed water of the AQC boiler 1 at the kiln head, reduces the load of the boiler, that is, reduces the usage amount of the heat exchange tubes in the AQC boiler 1 at the kiln head, and reduces the cost of the AQC boiler 1 at the kiln head; improves the deaeration effect of the deaerator 9, reduces the oxygen corrosion of the heat exchange pipes in the boilers (the AQC boiler 1 at the kiln head and the SP boiler 2 at the tail of the kiln), and improves the service life of (the AQC boiler 1 at the kiln head and the SP boiler 2 at the tail of the kiln); reduces the gas production in the low-pressure evaporation section of the AQC boiler 1 at the kiln head, increases the evaporation amount in the high-pressure section, and improves the operation stability and safety of the steam turbine 3.

[0054] In some possible implementation manners, it further includes a dust collection system respectively connected to the grate cooler 100 at the kiln head and the AQC boiler 1 at the kiln head;

[0055] The dust collection system includes a dust collector respectively connected to the AQC boiler 1 at the kiln head and the grate cooler 100 at the kiln head, an induced draft fan connected to the output end of the dust collector, and a chimney connected to the induced draft fan; the AQC boiler 1 at the kiln head and the grate cooler 100 at the kiln head are connected to the input end of the dust collector.

[0056] After the hot flue gas extracted from the cooler 100 at the kiln head exchanges heat in the AQC boiler 1 at the kiln head, low-pressure steam and high-pressure steam 1 are generated. After heat exchange, the flue gas and the excess hot flue gas in the cooler 100 at the kiln head will enter the dust collector for dust removal, and the gas will be discharged into the atmosphere from the chimney through the induced draft fan. The setting of the dust removal system 300 will effectively achieve environmental protection.

[0057] In some possible embodiments, a high-pressure induced draft fan is externally connected to the SP boiler 2 at the kiln tail, and the high-pressure induced draft fan is connected to the raw material drying system through a pipeline.

[0058] After the flue gas at the kiln tail exchanges heat in the SP boiler 2 at the kiln tail, it is sent to the raw material drying system of the cement plant through the high-pressure induced draft fan.

[0059] In some possible embodiments, a common economizer 11 connected to the feed water pump 10, a low-pressure steam drum 12, a low-pressure evaporator 13, a low-pressure superheater 14 connected to the low-pressure evaporator 13, a high-pressure economizer 1, a high-pressure steam drum 1, a high-pressure evaporator 1, and a high-pressure superheater 1 are provided in the AQC boiler 1 at the kiln head; the low-pressure steam drum 12, the low-pressure evaporator 13, and the low-pressure superheater 14 are sequentially connected to form a low-pressure system; the low-pressure superheater 14 is connected to the low-pressure heater 8; the low-pressure steam drum 12 is also connected to the low-pressure evaporator 13;

[0060] The high-pressure steam drum 1, the high-pressure evaporator 1, and the high-pressure superheater 1 are sequentially connected to form a high-pressure system; the high-pressure steam drum 1 is also connected to the high-pressure superheater 1;

[0061] The common economizer 11 is respectively connected to the low-pressure steam drum 12, the high-pressure economizer 1, and the SP boiler 2 at the kiln tail;

[0062] Specifically, after the condensate is heated and deaerated, it is transported to the common economizer 11 by the feed water pump 10. The common economizer 11 divides the condensate into three parts, one part enters the low-pressure steam drum 12, one part enters the high-pressure economizer 1, and the last part enters the SP boiler 2 at the kiln tail;

[0063] The condensate forms steam after heat exchange with the hot flue gas. This steam enters the low-pressure steam drum 12, and after passing through the low-pressure evaporator 13 and the low-pressure superheater 14, low-pressure steam will be generated. The low-pressure steam will be transported to the low-pressure heater 8 through the low-pressure steam outlet;

[0064] The condensate entering the high-pressure economizer 1 exchanges heat with the hot flue gas, then enters the high-pressure steam drum 1, and after passing through the high-pressure evaporator 1 and the high-pressure superheater 1, high-pressure steam 1 will be generated;

[0065] The condensate water entering the kiln tail SP boiler 2 exchanges heat with the flue gas at the kiln tail and generates high-pressure steam II. The high-pressure steam II enters the kiln head AQC boiler 1, where it is aggregated with the high-pressure steam I and then reheated to generate high-pressure steam, which then enters the steam turbine 3 for power generation.

[0066] In some possible embodiments, a high-pressure economizer II 21, a high-pressure steam drum II 22, a high-pressure evaporator II 23, and a high-pressure superheater II 24 are sequentially connected in the kiln tail SP boiler 2; the high-pressure economizer II 21 is connected to the common economizer 11; the high-pressure superheater II 24 is connected to the high-pressure superheater I 18; a common superheater 19 for connecting the high-pressure superheater II 24 and the high-pressure superheater I 18 respectively is arranged in the kiln head AQC boiler 1, and the common superheater 19 is connected to the steam turbine 3; the high-pressure steam drum II 22 is also connected to the high-pressure superheater II 24.

[0067] Specifically, the condensate water entering the kiln tail SP boiler 2 through the common economizer 11 will enter the high-pressure economizer II 21, exchange heat with the kiln tail flue gas in the kiln tail SP boiler 2, then enter the high-pressure steam drum II 22, and after passing through the high-pressure evaporator II 23 and the high-pressure superheater II 24, generate high-pressure steam II. The high-pressure steam II is aggregated with the high-pressure steam I, and then enters the common superheater 19 for reheating to generate high-pressure steam, which enters the steam turbine 3.

[0068] In some possible embodiments, the condensing assembly 5 includes a condenser and a water circulation system used in cooperation with the condenser; the condenser is connected to the low-pressure heater 8 and the condensate pump 6.

[0069] The condensing assembly 5 condenses the steam discharged from the low-pressure cylinder of the steam turbine 3 into water, and the formed condensate water will be sent back to the kiln head AQC boiler 1 and the kiln tail SP boiler 2 for circulation. At the same time, various drain waters are collected to reduce steam-water losses;

[0070] The condensate water condensed by the condenser is sent into the low-pressure heater 8 through the condensate pump 6, heated and then enters the deaerator 9. After deaeration, it passes through the feed water pump 10, enters the common economizer 11, and then is divided into three parts for utilization;

[0071] Specifically, the deaerator 9 is a vacuum deaerator;

[0072] By using the low-pressure heater 8 to heat the condensate water, the temperature of the feed water of the kiln head AQC boiler 1 is increased, the deaeration effect of the deaerator 9 is improved, the oxygen corrosion of the heat exchange pipes is reduced, and the service life is increased; the load of the economizer is reduced, that is, the usage amount of the economizer heat exchange tubes is reduced, and the cost of the boiler economizer is reduced.

[0073] In some possible embodiments, the low-pressure heaters 8 are two groups and are arranged in series;

[0074] Specifically, as Figure 1 shown, the low-pressure heater 8 is a set; as Figure 2 shown, the low-pressure heater 8 is two sets, including the first low-pressure heater 81 and the second low-pressure heater 82. The first low-pressure heater 81 is located between the shaft seal heater 7 and the second low-pressure heater 82. At this time, the low-pressure steam outlets will be two sets, and the temperatures of the low-pressure steam output by the two sets of low-pressure steam outlets are different. Among them, the first low-pressure heater 81 is used to transport the low-pressure steam with a lower temperature and is used to heat the condensate water, and the second low-pressure heater 82 is used to transport the low-pressure steam with a higher temperature and is used to heat the condensate water at the outlet of the second low-pressure heater 82; adopting this method avoids excessive expansion of the heat exchange pipes inside the low-pressure heater 8 and reduces the possibility of tube explosion.

[0075] A control method for a waste heat power generation system based on a low-pressure heater as described above specifically includes the following steps:

[0076] The flue gas at the kiln tail enters the kiln tail preheater 200 and then enters the kiln tail SP boiler 2 to heat the feed water, generating the second high-pressure steam. The second high-pressure steam is transported to the kiln head AQC boiler 1 for further heating;

[0077] At the same time, the hot flue gas extracted by the kiln head grate cooler 100 enters the kiln head AQC boiler 1 to heat the feed water, generating low-pressure steam through the low-pressure system in the dual-pressure system and generating the first high-pressure steam through the high-pressure system in the dual-pressure system;

[0078] The low-pressure steam is sent to the low-pressure heater 8 to heat the condensate water condensed by the condenser assembly 5. The low-pressure steam condenses into water after heat exchange, and this part of the water will be transported to the condenser assembly; the condensate water is transported to the kiln head AQC boiler 1 through the feed water pump 10;

[0079] After the first high-pressure steam and the second high-pressure steam are aggregated and reheated, they are sent to the inlet of the steam turbine 3 in the steam turbine house for power generation.

[0080] A control method for a waste heat power generation system based on a low-pressure heater as described above specifically includes the following steps:

[0081] The condensate water condensed by the condenser assembly 5 successively passes through the condensate water pump 6, the shaft seal heater 7, the low-pressure heater 8, the deaerator 9, and the feed water pump 10 and then is transported to the common economizer 11. The common economizer 11 transports the condensate water to the second high-pressure economizer 21 of the kiln tail SP boiler 2, the low-pressure steam drum 12 of the kiln head AQC boiler 1, and the first high-pressure economizer 15 of the kiln head AQC boiler 1 respectively;

[0082] Among them, part of the condensate water entering the second high-pressure economizer 21 of the kiln tail SP boiler 2, after heat exchange, passes through the second high-pressure evaporator 23 and the second high-pressure superheater 24 to generate the second high-pressure steam, and enters the common superheater 19 of the kiln head AQC boiler 1;

[0083] Part of the condensate that enters the high-pressure economizer-15 of the AQC boiler 1 at the kiln head is heat-exchanged, and after passing through the high-pressure evaporator-17 and the high-pressure superheater-18, high-pressure steam-1 is generated and enters the common superheater 19 of the AQC boiler 1 at the kiln head. After mixing with the high-pressure steam-2 generated by the high-pressure superheater-24 and passing through the common superheater 19, high-pressure steam is generated and transported to the steam turbine 3;

[0084] Part of the condensate that enters the AQC boiler 1 at the kiln head is heat-exchanged and then enters the low-pressure steam drum 12. After passing through the low-pressure evaporator 13 and the low-pressure superheater 14, low-pressure steam is generated and transported to the low-pressure heater 8.

[0085] The present invention and the existing traditional dual-pressure system are respectively applied to a waste heat power generation system of a 7000 t / h clinker production line. The power generation and the cost of the AQC boiler are shown in Table 1:

[0086]

[0087] Table 1

[0088] Under the same conditions, when the outlet flue gas and air temperature of the AQC boiler 1 at the kiln head drops to about 90 °C, the waste heat power generation system of the low-pressure heater 8 in the cement plant can achieve the same power generation as the traditional dual-pressure system, and the AQC boiler 1 at the kiln head reduces a certain cost; to a certain extent, the deaeration effect of the boiler feed water (the AQC boiler 1 at the kiln head and the SP boiler at the kiln tail) is improved; the operation stability of the waste heat power generation system is improved; the operation life of the boiler (the AQC boiler 1 at the kiln head and the SP boiler 2 at the kiln tail) and the steam turbine 3 is increased.

[0089] The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new feature or any new combination disclosed in this specification, as well as any new method or process step or any new combination disclosed.

Claims

1. A waste heat power generation system based on a low-pressure heater, characterized in that, It includes a kiln tail SP boiler connected to the preheater at the kiln tail, a kiln head AQC boiler connected to the kiln tail SP boiler and the kiln head grate cooler, and a steam turbine house connected to the kiln head AQC boiler; The steam turbine house includes a steam turbine connected to the kiln head AQC boiler, a generator connected to the steam turbine, a condenser assembly connected to the steam turbine, a condensate pump connected to the condenser assembly, a gland heater, low-pressure heaters, a deaerator, and a feed water pump; The condensate pump, gland heater, low-pressure heaters, deaerator, and feed water pump are connected in sequence; The low-pressure heaters are respectively connected to the low-pressure steam outlet of the kiln head AQC boiler and the condenser assembly, and the feed water pump is connected to the kiln head AQC boiler; The low-pressure steam is only used to heat the condensed water condensed by the condenser assembly and is not used for steam turbine power generation; The steam turbine is connected to the high-pressure steam outlet of the kiln head AQC boiler; In the kiln head AQC boiler, there are a common economizer connected to the feed water pump, a low-pressure steam drum, a low-pressure evaporator, a low-pressure superheater connected to the low-pressure evaporator, a high-pressure economizer I, a high-pressure steam drum I, a high-pressure evaporator I, and a high-pressure superheater I; The low-pressure steam drum, low-pressure evaporator, and low-pressure superheater are connected in sequence; The high-pressure steam drum I, high-pressure evaporator I, and high-pressure superheater I are connected in sequence; The common economizer is respectively connected to the low-pressure steam drum, high-pressure economizer I, and kiln tail SP boiler; In the kiln tail SP boiler, there are a high-pressure economizer II, a high-pressure steam drum II, a high-pressure evaporator II, and a high-pressure superheater II connected in sequence; The high-pressure economizer II is connected to the common economizer; The high-pressure superheater II is connected to the high-pressure superheater I; In the kiln head AQC boiler, there is a common superheater for the high-pressure superheater II and the high-pressure superheater I to be respectively connected, and the common superheater is connected to the steam turbine.

2. The waste heat power generation system based on a low-pressure heater according to claim 1, wherein It also includes a dust collection system respectively connected to the kiln head grate cooler and the kiln head AQC boiler.

3. The waste heat power generation system based on a low-pressure heater according to claim 2, wherein, The dust collection system includes a dust collector respectively connected to the kiln head AQC boiler and the kiln head grate cooler, an induced draft fan connected to the output end of the dust collector, and a chimney connected to the induced draft fan; The kiln head AQC boiler and the kiln head grate cooler are connected to the input end of the dust collector.

4. A waste heat power generation system based on a low-pressure heater according to claim 1, characterized in that, The kiln tail SP boiler is externally connected with a high-pressure induced draft fan, and the high-pressure induced draft fan is connected to the raw material drying system through a pipeline.

5. The waste heat power generation system based on a low-pressure heater according to claim 1, wherein The condenser assembly includes a condenser and a water circulation system used in cooperation with the condenser; The condenser is connected to the low-pressure heaters and the condensate pump.

6. A waste heat power generation system based on a low-pressure heater according to claim 5, characterized in that, The low-pressure heaters are two groups and are arranged in series.

7. A control method for a waste heat power generation system based on a low-pressure heater according to any one of claims 1-5, characterized in that, Specifically, it includes the following steps: The flue gas at the kiln tail enters the kiln tail SP boiler through the preheater at the kiln tail to heat the feed water to generate high-pressure steam II, which is transported to the kiln head AQC boiler for reheating; The hot flue gas extracted by the kiln head grate cooler enters the kiln head AQC boiler to heat the feed water, generating low-pressure steam and high-pressure steam I; The low-pressure steam is sent to the low-pressure heaters to heat the condensed water condensed by the condenser assembly, and the condensed water is transported to the kiln head AQC boiler through the feed water pump. The high-pressure steam formed by reheating the high-pressure steam I and the high-pressure steam II is sent to the steam turbine inlet in the steam turbine house for power generation.

8. The control method of a waste heat power generation system based on a low-pressure heater according to claim 7, characterized in that: The condensate passes through the condensate pump, gland heater, low-pressure heater, deaerator, and feed pump in sequence and is then transported to the common economizer. The common economizer distributes the condensate to the high-pressure economizer II of the kiln tail SP boiler, the low-pressure steam drum of the kiln head AQC boiler, and the high-pressure economizer I of the kiln head AQC boiler; Among them, part of the condensate entering the high-pressure economizer II of the kiln tail SP boiler exchanges heat, and then passes through the high-pressure evaporator II and high-pressure superheater II to generate high-pressure steam II, which enters the common superheater of the kiln head AQC boiler; Part of the condensate entering the high-pressure economizer I of the kiln head AQC boiler exchanges heat, and then passes through the high-pressure evaporator I and high-pressure superheater I to generate high-pressure steam I, which enters the common superheater of the kiln head AQC boiler and mixes with the high-pressure steam II passing through the high-pressure superheater II. After passing through the common superheater, high-pressure steam is generated and transported to the steam turbine; Part of the condensate entering the kiln head AQC boiler exchanges heat and then enters the low-pressure steam drum. After passing through the low-pressure evaporator and low-pressure superheater, low-pressure steam is generated and transported to the low-pressure heater. The low-pressure steam heats the condensate condensed by the condenser assembly in the low-pressure heater, and the low-pressure steam condenses into water after heat exchange. This part of the water will be transported to the condenser assembly; the condensate is then transported to the kiln head AQC boiler through the feed pump.

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