Waste heat power generation system based on low-pressure heater and control method

Abstract

The invention relates to the technical field of waste heat recovery, and particularly discloses a waste heat power generation system based on a low-pressure heater and a control method. The waste heat power generation system comprises a kiln tail SP boiler, a kiln head AQC boiler connected with the kiln tail SP boiler and a steam engine room; the steam turbine room comprises a steam turbine connected with the kiln head AQC boiler, a power generator connected with the steam turbine, a steam condensing assembly connected with the steam turbine, a condensate pump connected with the steam condensing assembly, a shaft seal heater, a low-pressure heater, a deaerator and a water feeding pump. The low-pressure heater is connected with a low-pressure steam outlet of the kiln head AQC boiler and the steam condensing assembly, and the water feeding pump is connected with the kiln head AQC boiler. The low-pressure heater is used for heating condensed water, the temperature of boiler feed water is increased, the load of a boiler economizer is reduced, the use amount of heat exchange tube bundles of the boiler economizer is reduced, and the cost of the boiler economizer is reduced; the deoxidizing effect of the deaerator is improved, oxygen corrosion of a heat exchange pipeline of the boiler is reduced, and the service life of the boiler is prolonged.

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 based on a low-pressure heater and a control method. Background Art

[0002] The cement production process consumes a large amount of fossil energy and electricity. 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 problem of electricity supply, the cement production process is equipped with a waste heat power generation system.

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

[0004] The waste heat power generation dual-pressure system of cement plants has many advantages, but due to the volatility of the cement plant's clinker burning process, the waste heat power generation system is not very stable. In particular, the low-pressure supplementary steam often cannot be supplemented into the steam turbine, and the supplementary steam port is prone to condensation, which affects 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 control method based on a low-pressure heater;

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

[0007] A waste heat power generation system based on a low-pressure heater, comprising 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 engine room connected to the kiln head AQC boiler;

[0008] The steam engine room 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 shaft seal heater, a low-pressure heater, a deaerator, and a feed water pump;

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

[0010] The low-pressure heater is respectively connected to the low-pressure steam outlet and the condensing assembly of the kiln head AQC boiler, 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] The present invention connects the low-pressure heater with the low-pressure steam outlet of the kiln head AQC boiler, so that the low-pressure steam is only used to heat the condensed water condensed by the condensing assembly, and is not used for steam turbine power generation; the condensed water is heated by the low-pressure heater to increase the temperature of the boiler feed water, and the load of the boiler economizer is reduced, that is, the usage of the boiler economizer heat exchange tube bundle is reduced, and the cost of the boiler economizer is reduced; the deoxidation effect of the deaerator is improved, the oxygen corrosion of the boiler heat exchange pipe is reduced, and the service life of the boiler is increased; the gas production of the low-pressure evaporation section of the kiln head AQC boiler is reduced, the evaporation amount of the high-pressure section is increased, and the operating stability and safety of the steam turbine are improved.

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

[0014] In some possible implementations, the dust collection system includes a dust collector connected to the kiln head AQC boiler and the kiln head grate cooler respectively, 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.

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

[0016] In some possible implementations, a common economizer connected to a feed water pump, a low-pressure drum, a low-pressure evaporator, a low-pressure superheater connected to the low-pressure evaporator, a high-pressure economizer 1, a high-pressure drum 1, a high-pressure evaporator 1, and a high-pressure superheater 1 are provided in the kiln head AQC boiler; the low-pressure drum, the low-pressure evaporator, and the low-pressure superheater are connected in sequence;

[0017] The high-pressure steam drum 1, the high-pressure evaporator 1, and the high-pressure superheater 1 are connected in sequence;

[0018] The common economizer is respectively connected to the low-pressure steam drum, the high-pressure economizer 1, and the kiln tail SP boiler.

[0019] In some possible embodiments, the kiln tail SP boiler is provided with a high-pressure economizer 2, a high-pressure steam drum 2, a high-pressure evaporator 2, and a high-pressure superheater 2 which are connected in sequence; the high-pressure economizer 2 is connected to a common economizer; the high-pressure superheater 2 is connected to a high-pressure superheater 1; a common superheater for connecting the high-pressure superheater 2 and the high-pressure superheater 1 respectively is provided in the kiln head AQC boiler, and the common superheater is connected to a steam turbine.

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

[0021] In some possible implementations, the low-pressure heaters are in two groups and are arranged in series.

[0022] A control method for a waste heat power generation system based on a low-pressure heater according to the above-mentioned method specifically comprises the following steps:

[0023] The flue gas at the kiln tail passes through the kiln tail preheater and enters the kiln tail SP boiler to heat the feed water to produce high-pressure steam, 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.

[0025] The low-pressure steam is sent to the low-pressure heater to heat the condensate condensed by the condensing assembly. The condensate is transported to the kiln head AQC boiler through the feed water pump. The high-pressure steam is combined with the high-pressure steam and then reheated to generate high-pressure steam, which is transported to the turbine inlet of the steam engine room for power generation.

[0026] In some possible implementations, the condensate is sequentially transported to the public economizer after passing through the condensate pump, the shaft seal heater, the low-pressure heater, the deaerator, and the feed water pump. The public economizer transports the condensate to the high-pressure economizer 2 of the SP boiler at the kiln tail, the low-pressure drum of the AQC boiler at the kiln head, and the high-pressure economizer 1 of the AQC boiler at the kiln head;

[0027] Among them, part of the condensate entering the high-pressure economizer 2 of the SP boiler at the kiln tail will undergo heat exchange, pass through the high-pressure evaporator 2 and the high-pressure superheater 2, and generate high-pressure steam 2, which will enter the common superheater of the AQC boiler at the kiln head;

[0028] After heat exchange, part of the condensate entering the high-pressure economizer 1 of the kiln head AQC boiler passes through the high-pressure evaporator 1 and the high-pressure superheater 1 to generate high-pressure steam 1, which enters the common superheater of the kiln head AQC boiler and mixes with the high-pressure steam 2 that passes through the high-pressure superheater 2. After passing through the common superheater, it generates high-pressure steam and is transported to the steam turbine;

[0029] Part of the condensate entering the kiln head AQC boiler enters the low-pressure steam drum after heat exchange, and generates low-pressure steam after passing through the low-pressure evaporator and low-pressure superheater, which is then transported to the low-pressure heater.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention utilizes a low-pressure heater to heat condensate, thereby increasing the temperature of boiler feed water and reducing the load of a boiler economizer, that is, reducing the usage of a boiler economizer heat exchange tube bundle and reducing the cost of a boiler economizer;

[0032] The present invention utilizes a low-pressure heater to heat condensate, thereby increasing the temperature of boiler feed water, improving the deoxidation effect of the deaerator, reducing oxygen corrosion of 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 kiln head AQC boiler, increases the evaporation capacity of the high-pressure section, and improves the operating stability and safety of the steam turbine;

[0034] The present invention can adapt to the temperature in winter and the output of the cement plant clinker line. The kiln head AQC boiler can adopt a dual-pressure system, thereby improving the waste heat recovery efficiency of the cement plant.

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

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

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

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

[0039] Among them: 100, kiln head grate cooler; 200, kiln tail preheater; 300, dust removal system; 1, kiln head AQC boiler; 11, public economizer; 12, low-pressure steam drum; 13, low-pressure evaporator; 14, low-pressure superheater; 15, high-pressure economizer 1; 16, high-pressure steam drum 1; 17, high-pressure evaporator 1; 18, high-pressure superheater 1; 19, public superheater; 2, kiln tail SP boiler; 21, high-pressure economizer 2; 22, high-pressure steam drum 2; 23, high-pressure evaporator 2; 24, high-pressure heater 2; 3, steam turbine; 4, generator; 5, condensing assembly; 6, condensate pump; 7, shaft seal heater; 8, low-pressure heater; 81, low-pressure heater 1; 82, low-pressure heater 2; 9, deaerator; 10, feed water pump. DETAILED DESCRIPTION

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. 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, "one" or "one" and other similar words do not indicate a quantity restriction, but indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" refers to two or more. For example, multiple positioning columns refer to two or more positioning columns. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The present invention is described in detail below.

[0042] like Figure 1-Figure 3 As shown:

[0043] A waste heat power generation system based on a low-pressure heater is applied to waste heat recovery in a cement plant, comprising 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 engine room connected to the kiln head AQC boiler 1;

[0044] The steam engine room 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 shaft seal heater 7, a low-pressure heater 8, a deaerator 9, and a feed water pump 10;

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

[0046] The low-pressure heater 8 is connected to the low-pressure steam outlet of the kiln head AQC boiler 1 and the condensing assembly 5 respectively, 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] When in use, the kiln head grate cooler 100 in the cement burning system extracts hot flue gas with a relatively high temperature into the kiln head AQC boiler 1, and discharges the hot flue gas into the atmosphere after heat exchange in the kiln head AQC boiler 1;

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

[0050] The condensed water condensed by the condensing assembly 5 is sent to the low-pressure heater 8 through the condensate pump 6 and the shaft seal heater 7 for heating and then enters the deaerator 9. After being deoxidized by the deaerator 9, part of the condensed water is sent to the kiln head AQC boiler 1 through the feed water pump 10, and after heat exchange with the hot flue gas, low-pressure steam and high-pressure steam 1 are generated; part of the condensed water will be transported to the kiln tail SP boiler 2 through the kiln head AQC boiler 1, and heat exchange with the flue gas at the kiln tail to generate high-pressure steam 2;

[0051] High-pressure steam 2 and high-pressure steam 1 are collected and reheated, and enter steam turbine 3 through the high-pressure steam outlet to generate electricity; the heat carried by the low-grade waste heat flue gas is converted into high-grade water vapor, and sent to steam turbine generator 4 to generate electricity;

[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. The low-pressure steam condenses into water after heat exchange, and this part of water will be transported to the condensing component; the condensed water is transported to the kiln head AQC boiler 1 through the feed water pump 10.

[0053] The present invention connects the low-pressure steam outlet of the kiln head AQC boiler 1 through the low-pressure heater 8, so that the low-pressure steam is only used to heat the condensed water condensed by the condensing assembly 5, and is not used for power generation of the steam turbine 3; the condensed water is heated by the low-pressure heater 8 to increase the temperature of the feed water of the kiln head AQC boiler 1, and the load of the boiler is reduced, that is, the use of the heat exchange tube bundle in the kiln head AQC boiler 1 is reduced, and the cost of the kiln head AQC boiler 1 is reduced; the deoxidation effect of the deaerator 9 is improved, the oxygen corrosion of the heat exchange pipes in the boilers (kiln head AQC boiler 1 and kiln tail SP boiler 2) is reduced, and the service life of (kiln head AQC boiler 1 and kiln tail SP boiler 2) is increased; the gas production of the low-pressure evaporation section in the kiln head AQC boiler 1 is reduced, the evaporation amount of the high-pressure section is increased, and the operation stability and safety of the steam turbine 3 are improved.

[0054] In some possible implementations, a dust collection system is further included which is respectively connected to the kiln head grate cooler 100 and the kiln head AQC boiler 1;

[0055] The dust collection system includes a dust collector connected to the kiln head AQC boiler 1 and the kiln head grate cooler 100 respectively, 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 1 and the kiln head grate cooler 100 are connected to the input end of the dust collector.

[0056] The hot flue gas extracted from the kiln head grate cooler 100 undergoes heat exchange in the kiln head AQC boiler 1 to generate low-pressure steam and high-pressure steam 1. The flue gas after heat exchange and the excess hot flue gas in the kiln head grate cooler 100 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 implementations, the kiln tail SP boiler 2 is externally connected to a high-pressure induced draft fan, and the high-pressure induced draft fan is connected to the raw material drying system through a pipeline.

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

[0059] In some possible implementations, a common economizer 11 connected to a feed water pump 10, a low-pressure drum 12, a low-pressure evaporator 13, a low-pressure superheater 14 connected to the low-pressure evaporator 13, a high-pressure economizer 15, a high-pressure drum 16, a high-pressure evaporator 17, and a high-pressure superheater 18 are provided in the kiln head AQC boiler 1; the low-pressure 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 drum 12 is also connected to the low-pressure evaporator 13;

[0060] The high-pressure steam drum 16, the high-pressure evaporator 17, and the high-pressure superheater 18 are connected in sequence to form a high-pressure system; the high-pressure steam drum 16 is also connected to the high-pressure superheater 18;

[0061] The public economizer 11 is respectively connected to the low-pressure drum 12, the high-pressure economizer 15, and the kiln tail SP boiler 2;

[0062] Specifically, the condensate is heated and deoxygenated and then transported to the public economizer 11 through the feed water pump 10. The public economizer 11 divides the condensate into three parts, one of which enters the low-pressure drum 12, one enters the high-pressure economizer 15, and the last part enters the kiln tail SP boiler 2;

[0063] The condensed water forms steam after heat exchange with the hot flue gas. The steam enters the low-pressure drum 12, passes through the low-pressure evaporator 13 and the low-pressure superheater 14, and generates low-pressure steam. The low-pressure steam is transported to the low-pressure heater 8 through the low-pressure steam outlet.

[0064] The condensed water entering the high-pressure economizer 15 exchanges heat with the hot flue gas, and then enters the high-pressure steam drum 16, and after passing through the high-pressure evaporator 17 and the high-pressure superheater 18, high-pressure steam is generated;

[0065] The condensate entering the SP boiler 2 at the kiln tail exchanges heat with the flue gas at the kiln tail to generate high-pressure steam 2. The high-pressure steam 2 enters the AQC boiler 1 at the kiln head and is combined with the high-pressure steam 1 for reheating to generate high-pressure steam, which then enters the steam turbine 3 to generate electricity.

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

[0067] Specifically, the condensate entering the kiln tail SP boiler 2 through the common economizer 11 will enter the high-pressure economizer 2 21, exchange heat with the kiln tail flue gas in the kiln tail SP boiler 2, and then enter the high-pressure steam drum 2 22, and after passing through the high-pressure evaporator 2 23 and the high-pressure superheater 2 24, high-pressure steam 2 is generated. The high-pressure steam 2 is combined with the high-pressure steam 1, and then enters the common superheater 19 for reheating to generate high-pressure steam, which enters the steam turbine 3.

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

[0069] The condensing assembly 5 condenses the steam discharged from the low-pressure cylinder of the steam turbine 3 into water. The condensed 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 drainages are collected to reduce steam and water losses.

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

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

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

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

[0074] Specifically, Figure 1 As shown, the low-pressure heater 8 is a group; Figure 2 As shown, the low-pressure heater 8 is divided into two groups, including a low-pressure heater 1 81 and a low-pressure heater 2 82. The low-pressure heater 1 81 is located between the shaft seal heater 7 and the low-pressure heater 2 82. At this time, the low-pressure steam outlet will be divided into two groups, and the temperatures of the low-pressure steam output by the two groups of low-pressure steam outlets are different. The low-pressure heater 1 81 is used to transport low-pressure steam with a lower temperature and to heat condensate, and the low-pressure heater 2 82 is used to transport low-pressure steam with a higher temperature and to heat condensate at the outlet of the low-pressure heater 8Ⅰ. This method avoids excessive expansion of the internal heat exchange pipe of the low-pressure heater 8 and reduces the possibility of pipe burst.

[0075] A control method for a waste heat power generation system based on a low-pressure heater according to the above-mentioned method specifically comprises the following steps:

[0076] The flue gas at the kiln tail passes through the kiln tail preheater 200 and enters the kiln tail SP boiler 2 to heat the feed water, generating high pressure steam 2, which is then 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, generates low-pressure steam through the low-pressure system in the dual-pressure system, and generates high-pressure steam one 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 condensed water condensed by the condensing assembly 5. The low-pressure steam condenses into water after heat exchange, and this part of water will be sent to the condensing assembly; the condensed water is sent to the kiln head AQC boiler 1 through the feed water pump 10;

[0079] High-pressure steam 1 and high-pressure steam 2 are collected and reheated, and then sent to the inlet of turbine 3 in the steam engine room for power generation.

[0080] A control method for a waste heat power generation system based on a low-pressure heater according to the above-mentioned method specifically comprises the following steps:

[0081] The condensed water from the condensing assembly 5 is sequentially transported to the public economizer 11 through the condensate pump 6, the shaft seal heater 7, the low-pressure heater 8, the deaerator 9, and the feed water pump 10. The public economizer 11 transports the condensed water to the high-pressure economizer 21 of the SP boiler 2 at the kiln tail, the low-pressure drum 12 of the AQC boiler 1 at the kiln head, and the high-pressure economizer 1 15 of the AQC boiler 1 at the kiln head;

[0082] Among them, part of the condensate entering the high-pressure economizer 21 of the kiln tail SP boiler 2 is heat exchanged, passes through the high-pressure evaporator 23 and the high-pressure superheater 24, and generates high-pressure steam 2, which enters the common superheater 19 of the kiln head AQC boiler 1;

[0083] After heat exchange, part of the condensate entering the high-pressure economizer 15 of the kiln head AQC boiler 1 passes through the high-pressure evaporator 17 and the high-pressure superheater 18 to generate high-pressure steam 1, which enters the common superheater 19 of the kiln head AQC boiler 1 and is mixed with the high-pressure steam 2 generated by the high-pressure superheater 24. After passing through the common superheater 19, high-pressure steam is generated and transported to the steam turbine 3;

[0084] Part of the condensate entering the kiln head AQC boiler 1 enters the low-pressure steam drum 12 after heat exchange, and generates low-pressure steam after passing through the low-pressure evaporator 13 and the low-pressure superheater 14, which is then 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 7000t / h clinker line. The power generation and AQC boiler cost are shown in Table 1:

[0086]

[0087] Table 1

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

[0089] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A waste heat power generation system based on a low-pressure heater, characterized in that: It includes the kiln tail SP boiler connected to the kiln tail preheater, the kiln head AQC boiler connected to the kiln tail SP boiler and the kiln head grate cooler, and the steam engine room connected to the kiln head AQC boiler; The steam engine room 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 shaft seal heater, a low-pressure heater, a deaerator, and a feed water pump; The condensate pump, shaft seal heater, low-pressure heater, deaerator, and feed water pump are connected in sequence; The low-pressure heater is respectively connected to the low-pressure steam outlet and the condensing assembly of the kiln head AQC boiler, and the feed water pump is connected to the kiln head AQC boiler; The steam turbine is connected to the high-pressure steam outlet of the kiln head AQC boiler.

2. A waste heat power generation system based on a low-pressure heater according to claim 1, characterized in that: It also includes a dust collection system which is respectively connected to the kiln head grate cooler and the kiln head AQC boiler.

3. A waste heat power generation system based on a low-pressure heater according to claim 2, characterized in that: The dust collection system includes a dust collector connected to the kiln head AQC boiler and the kiln head grate cooler respectively, 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 SP boiler at the kiln tail 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, characterized in that: The kiln head AQC boiler is provided with a common economizer connected to a feed water pump, a low-pressure drum, a low-pressure evaporator, a low-pressure superheater connected to the low-pressure evaporator, a high-pressure economizer 1, a high-pressure drum 1, a high-pressure evaporator 1, and a high-pressure superheater 1; the low-pressure drum, the low-pressure evaporator, and the low-pressure superheater are connected in sequence; The high-pressure steam drum 1, the high-pressure evaporator 1, and the high-pressure superheater 1 are connected in sequence; The common economizer is respectively connected to the low-pressure steam drum, the high-pressure economizer 1, and the kiln tail SP boiler.

6. A waste heat power generation system based on a low-pressure heater according to claim 5, characterized in that: The SP boiler at the kiln tail is provided with a high-pressure economizer 2, a high-pressure steam drum 2, a high-pressure evaporator 2, and a high-pressure superheater 2 which are connected in sequence; the high-pressure economizer 2 is connected to a common economizer; the high-pressure superheater 2 is connected to a high-pressure superheater 1; a common superheater for connecting the high-pressure superheater 2 and the high-pressure superheater 1 respectively is provided in the AQC boiler at the kiln head, and the common superheater is connected to a steam turbine.

7. A waste heat power generation system based on a low-pressure heater according to claim 1, characterized in that: The condensing assembly comprises a condenser and a water circulation system used in conjunction with the condenser; the condenser is connected to a low-pressure heater and a condensate pump.

8. A waste heat power generation system based on a low-pressure heater according to claim 7, characterized in that: The low-pressure heaters are divided into two groups and are arranged in series.

9. A control method for a waste heat power generation system based on a low-pressure heater according to any one of claims 1 to 8, characterized in that: The specific steps include: The flue gas at the kiln tail passes through the kiln tail preheater and enters the kiln tail SP boiler to heat the feed water to produce high-pressure steam, which is then transported to the kiln head AQC boiler for further heating; 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. The low-pressure steam is sent to the low-pressure heater to heat the condensate condensed by the condensing assembly. The condensate is transported to the kiln head AQC boiler through the feed water pump. The high-pressure steam formed by reheating high-pressure steam 1 and high-temperature steam 2 is sent to the turbine inlet of the steam engine room for power generation.

10. The control method of a waste heat power generation system based on a low-pressure heater according to claim 9, characterized in that: The condensate is transported to the public economizer after passing through the condensate pump, shaft seal heater, low-pressure heater, deaerator, and feed water pump in sequence. The public economizer transports the condensate to the high-pressure economizer 2 of the SP boiler at the kiln tail, the low-pressure drum of the AQC boiler at the kiln head, and the high-pressure economizer 1 of the AQC boiler at the kiln head; Among them, part of the condensate entering the high-pressure economizer 2 of the SP boiler at the kiln tail will undergo heat exchange, pass through the high-pressure evaporator 2 and the high-pressure superheater 2, and generate high-pressure steam 2, which will enter the common superheater of the AQC boiler at the kiln head; After heat exchange, part of the condensate entering the high-pressure economizer 1 of the kiln head AQC boiler passes through the high-pressure evaporator 1 and the high-pressure superheater 1 to generate high-pressure steam 1, which enters the common superheater of the kiln head AQC boiler and mixes with the high-pressure steam 2 that passes through the high-pressure superheater 2. After passing through the common superheater, it generates high-pressure steam and is transported to the steam turbine; Part of the condensate entering the kiln head AQC boiler enters the low-pressure steam drum after heat exchange, and generates low-pressure steam after passing through the low-pressure evaporator and low-pressure superheater, which is transported to the low-pressure heater. The low-pressure steam heats the condensate condensed by the condensing component through the low-pressure heater. The low-pressure steam condenses into water after heat exchange, and this part of water will be transported to the condensing component; the condensate is transported to the kiln head AQC boiler through the feed water pump.

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