Boiler waste heat composite utilization system and method

Abstract

The invention relates to the technical field of boiler flue gas waste heat utilization, and particularly discloses a boiler waste heat composite utilization system and method.The system comprises a boiler and a sulfur removal tower, and the boiler is connected with the sulfur removal tower; the boiler flue gas desulfurization system is used for carrying out flue gas desulfurization on boiler flue gas and is connected with the desulfurization tower through a pipeline; the flue gas guide and drainage system is used for shunting desulfurized flue gas output by the boiler flue gas desulfurization system and respectively guiding and shunting the desulfurized flue gas to the air preheating system, the lignite drying system, the hot water network heating system and the condensed water heating system through four passages; the air preheating system is connected with the boiler; the flue gas guide drainage system synchronously controls the air preheating system and the lignite drying system; and the flue gas guide drainage system synchronously controls the hot water network heating system and the condensate water warming system. According to the invention, the flue gas waste heat discharged by the boiler can be effectively recovered and used for multiple purposes, so that the utilization efficiency of energy is remarkably improved, and the energy waste is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler flue gas waste heat utilization, and in particular to a boiler waste heat composite utilization system and method. Background Art

[0002] Nowadays, the initial parameters of the steam at the outlet of the supercritical boiler have reached a main steam pressure of 30Mpa, a main steam temperature of 600°C, and a reheat temperature of 620°C. The boiler efficiency is close to 95%. The boiler combustion technology and turbine design are already quite mature. Improving efficiency from the design of the boiler and turbine body is the limit of the technology in this field. According to the boiler counter-balance method, the boiler efficiency η=10-(q2+q3+q4+q5) where: q2: exhaust heat loss-the main heat loss of the boiler; q3: chemical incomplete combustion heat loss-refers to the loss caused by the incomplete combustion of the combustible gas generated during the combustion process; q4: mechanical incomplete combustion loss-the heat loss caused by the incomplete combustion of carbon discharged from the furnace along with the ash; q5: heat dissipation loss-the heat generated by the boiler is dissipated through the furnace body, steam-water pipes, smoke and air ducts and other equipment; q6: ash physical heat loss-the heat taken away by the slag discharge; Based on conventional design in the field, for large-capacity and high-parameter pulverized coal boilers, the flue gas temperature at the air preheater outlet is generally between 120C and 130C. There is basically no potential for q3, q4, q5, and q6, but the situation is quite different for q2. The biggest loss affecting boiler efficiency is the heat loss of flue gas, which accounts for about 69%-9%. In terms of improving the power generation economy and boiler efficiency of the entire plant, reducing the flue gas loss plays a very important role.

[0003] Existing exhaust waste heat recovery and utilization devices mostly use complex pipeline forms or the principle of energy cascade utilization. They can only be connected to one or several of the air preheating system, lignite drying system, hot water network heating system, condensate heating system and heat recovery steam extraction system to maintain safe efficiency and stability of operation. These two methods result in very little heat being absorbed in the system that finally absorbs the waste heat, uneven heat distribution that cannot be adjusted, or too much heat being wasted in pipeline transmission.

[0004] Based on this, how to propose a technical solution for utilizing the waste heat of boiler flue gas to improve the power generation economy and boiler efficiency of the entire plant has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects existing in the above-mentioned prior art, thereby providing a system and method for composite utilization of boiler waste heat.

[0006] A boiler waste heat composite utilization system comprises: a boiler and a desulfurization tower, wherein the boiler and the desulfurization tower are connected; the system further comprises: A boiler flue gas desulfurization system for desulfurizing boiler flue gas; the boiler flue gas desulfurization system is connected to a desulfurization tower pipeline; and a flue gas guiding and drainage system for diverting the desulfurized flue gas outputted from the boiler flue gas desulfurization system to the air preheating system, the lignite drying system, the hot water network heating system and the condensate heating system through four passages; The air preheating system is connected to the boiler; The smoke guiding and drainage system synchronously controls the air preheating system and the lignite drying system; The flue gas guidance and drainage system synchronously controls the hot water network heating system and the condensate water heating system.

[0007] Preferably, the boiler flue gas desulfurization system comprises: a blower, a dust removal mechanism, a drying mechanism and a catalytic heating mechanism connected in sequence.

[0008] Preferably, the smoke guiding and drainage system comprises an induced draft fan, a five-way pipe, a solenoid valve and a solenoid valve controller which are connected in sequence; The five-way pipe has an inlet and two pairs of outlets arranged opposite to each other, and each outlet is connected to a solenoid valve; The solenoid valve controller includes: a front-end solenoid valve controller and a rear-end solenoid valve controller. The two electromagnetic valves arranged opposite to each other are respectively controlled by a front electromagnetic valve controller or a rear electromagnetic valve controller.

[0009] Preferably, the air preheating system comprises: a heating system, a heat transfer medium mechanism, a heat exchanger and a cold air heater which are connected in sequence.

[0010] Preferably, the lignite drying system is a drum dryer; The drum dryer is provided with a feed port at the top, a discharge port at the bottom and a smoke inlet on the side wall, and the smoke inlet is connected to the five-way pipe in the smoke guide and drainage system through a pipeline.

[0011] Preferably, the hot water network heating system comprises an anti-corrosion tubular heat exchanger and a water heating system hot network joint connected in sequence; The other end of the hot network joint of the water heating system is connected to any one of the hot network circulating water circuits of the heating plant or the hot network circulating water circuits of the plant area water heating system.

[0012] Preferably, the solenoid valve controller further comprises: a mid-end solenoid valve controller; The front-end solenoid valve controller and the rear-end solenoid valve controller are connected through the middle-end solenoid valve controller.

[0013] Preferably, the condensed water heating system comprises a flue gas heat recovery heater and a water-to-water heat exchanger which are connected in sequence.

[0014] A method for composite utilization of boiler waste heat, which is implemented based on the composite utilization system of boiler waste heat according to claim 8 for implementing the method, comprises the following steps: The flue gas generated by the boiler enters the desulfurization tower for desulfurization treatment; The desulfurized flue gas enters the boiler flue gas desulfurization system for further treatment to remove the remaining sulfur components in the flue gas; The treated flue gas is diverted through the flue gas guide and drainage system and input into the air preheating system, lignite drying system, hot water network heating system and condensate heating system; The air preheating system and the lignite drying system are controlled synchronously; the hot water network heating system and the condensed water heating system are controlled synchronously.

[0015] The technical solution of the present invention has the following advantages: Through the five-way pipe, it is connected to the air preheating system to replace or reduce the auxiliary steam consumption. The saved auxiliary steam can increase the power generation of the unit. Through the five-way pipe, it is connected to the lignite drying system, and the flue gas waste heat is used to dry part of the external moisture of the lignite, which greatly reduces coal consumption and increases power generation. Through the five-way pipe, it is connected to the hot water network heating system to achieve the purpose of saving the steam volume of the heat exchanger, which conforms to the principle of cascade utilization and rational use of energy, and conforms to the purpose of a conservation and environmentally friendly society. Through the five-way pipe, it is connected to the condensate heating system to increase the condensate temperature, and it is convenient to set up a connection with the heat recovery extraction system on this basis to reduce the required steam turbine extraction volume. This method reduces the steam extraction volume of the heat recovery system, thereby improving the absolute internal efficiency and cycle thermal efficiency of the steam turbine, so that the unit obtains additional electrical power. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a detailed structural diagram of the system of the present invention; Figure 2 It is a schematic diagram of the overall system structure of the present invention; Figure 3 This is a schematic diagram of the structure of the smoke guiding and drainage system of the present invention; Figure 4 This is a schematic diagram of the structure of the lignite drying system of the present invention.

[0018] Reference numerals: 100 boiler flue gas desulfurization system, 110 blower, 120 dust removal mechanism, 130 drying mechanism, 140 catalytic heating mechanism, 200 flue gas guide and drainage system, 210 induced draft fan, 220 five-way pipe, 230 solenoid valve, 240 solenoid valve controller, 241 front-end solenoid valve controller, 242 mid-end solenoid valve controller, 243 rear-end solenoid valve controller, 300 air preheating system, 310 heating system, 320 heat transfer medium mechanism, 330 heat exchanger, 340 cold air heater, 400 lignite drying system, 410 drum dryer, 420 feed inlet, 430 discharge port, 440 flue gas inlet, 500 hot water network heating system, 510 anti-corrosion tubular heat exchanger, 520 water heating system hot network joint, 600 condensate heating system, 610 flue gas heat recovery heater, 620 water-to-water heat exchanger. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Example 1 This embodiment discloses a boiler waste heat composite utilization system, including: a boiler and a desulfurization tower, characterized in that the boiler and the desulfurization tower are connected; the system also includes: A boiler flue gas desulfurization system 100 for desulfurizing boiler flue gas; the boiler flue gas desulfurization system 100 is connected to a desulfurization tower pipeline; and a flue gas guiding and drainage system 200 for diverting the desulfurized flue gas outputted from the boiler flue gas desulfurization system 100 to the air preheating system 300, the lignite drying system 400, the hot water network heating system 500 and the condensate heating system 600 through four passages; The air preheating system 300 is connected to the boiler; The smoke guiding and drainage system 200 synchronously controls the air preheating system 300 and the lignite drying system 400; The smoke guiding and drainage system 200 synchronously controls the hot water network heating system 500 and the condensed water heating system 600.

[0024] Specifically: The boiler flue gas desulfurization system 100 includes: a blower 110, a dust removal mechanism 120, a drying mechanism 130 and a catalytic heating mechanism 140 which are connected in sequence.

[0025] The smoke guiding and drainage system 200 includes an induced draft fan 210, a five-way pipe 220, a solenoid valve 230 and a solenoid valve controller 240 which are connected in sequence; The five-way pipe 220 has an inlet and two pairs of oppositely arranged outlets, each of which is connected to a solenoid valve 230; The solenoid valve controller 240 includes: a front-end solenoid valve controller 241 and a rear-end solenoid valve controller 243; The two oppositely arranged solenoid valves 230 are controlled by a front-end solenoid valve controller 241 or a rear-end solenoid valve controller 243 respectively.

[0026] The solenoid valve controller 240 further includes: a mid-end solenoid valve controller 242; The front end solenoid valve controller 241 and the rear end solenoid valve controller 243 are connected via the middle end solenoid valve controller 242 .

[0027] The air preheating system 300 includes: a heating system 310, a heat transfer medium mechanism 320, a heat exchanger 330 and a cold air heater 340 connected in sequence. The air preheating system 300 is connected to the boiler, specifically: the output end of the cold air heater 340 is connected to the boiler.

[0028] The lignite drying system 400 is a drum dryer 410; The drum dryer 410 is provided with a feed inlet 420 at the top, a discharge port 430 at the bottom, and a smoke inlet 440 on the side wall, and the smoke inlet 440 is connected to the five-way pipe 220 in the smoke guide and drainage system 200 through a pipe. The drum dryer 410 used in this embodiment is a rotatable cylinder with an inclination angle of 2º-10º. The wet material enters from the upper feed inlet 420, and the dry material is collected from the lower discharge port 430 at the other end. Hot smoke above 150°C enters from the smoke inlet 440 and is discharged from the upper smoke outlet at the other end. The solid wet material stays inside the drum dryer 410 for 12 to 14 minutes, and the smoke temperature at the smoke outlet drops to about 120°C. The drum dryer 410 is equipped with forward lifting plates at different angles so that the material is continuously lifted up and sprinkled down during the rotation of the drum, so that the wet material is fully in direct contact with the incoming hot flue gas, thereby improving the drying efficiency and moving the material forward. A chain is also fixed in the drum dryer 410 to clean the inner wall and stir the internal material.

[0029] As another embodiment: the structure of a single lifting plate inside the drum dryer 410 is: a stepped sawtooth shape; The hot water network heating system 500 includes an anti-corrosion tubular heat exchanger 510 and a water heating system hot network connector 520 connected in sequence; The other end of the water heating system heat network connector 520 is connected to any one of the heat network circulating water circuits of the heating plant or the heat network circulating water circuits of the plant area water heating system.

[0030] The condensed water heating system 600 includes a flue gas heat recovery heater 610 and a water-to-water heat exchanger 620 which are connected in sequence.

[0031] Example 2 A method for composite utilization of boiler waste heat is implemented based on the device of the embodiment; the method comprises the following steps: The flue gas generated by the boiler enters the desulfurization tower for desulfurization treatment; The desulfurized flue gas enters the boiler flue gas desulfurization system 100 for further processing to remove the remaining sulfur components in the flue gas; The treated flue gas is divided through the flue gas guiding and drainage system 200, and a part of it flows to the air preheating system 300 to preheat the air required for boiler combustion.

[0032] Another part of the flue gas flows to the lignite drying system 400 to dry the lignite and improve the combustion efficiency of the lignite; At the same time, the flue gas guiding and drainage system 200 also guides the flue gas to the hot water network heating system 500 and the condensate heating system 600 respectively, heats and raises the temperature of the hot water network and the condensate, thereby heating the hot water network to provide hot water for domestic or industrial use; and raising the temperature of the condensate to improve the reuse value of the condensate.

[0033] Synchronous control method: The flue gas guiding and drainage system 200 synchronously controls the air preheating system 300 and the lignite drying system 400 to ensure the balance of flue gas supply between the two systems. Similarly, the hot water network heating system 500 and the condensate heating system 600 are also synchronously controlled to achieve efficient energy utilization.

[0034] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A boiler waste heat composite utilization system, comprising: The boiler and the desulfurization tower are connected; the system further comprises: A boiler flue gas desulfurization system (100) for desulfurizing boiler flue gas; the boiler flue gas desulfurization system (100) is connected to a desulfurization tower pipeline; and a flue gas guiding and drainage system (200) for diverting desulfurized flue gas output from a boiler flue gas desulfurization system (100) and guiding the desulfurized flue gas to an air preheating system (300), a lignite drying system (400), a hot water network heating system (500), and a condensate heating system (600) through four passages; The air preheating system (300) is connected to the boiler; The smoke guiding and drainage system (200) synchronously controls the air preheating system (300) and the lignite drying system (400); The smoke guiding and drainage system (200) synchronously controls the hot water network heating system (500) and the condensed water heating system (600).

2. The boiler waste heat composite utilization system according to claim 1 is characterized in that: The boiler flue gas desulfurization system (100) comprises: a blower (110), a dust removal mechanism (120), a drying mechanism (130), and a catalytic heating mechanism (140) which are connected in sequence.

3. The boiler waste heat composite utilization system according to claim 2 is characterized in that: The smoke guiding and drainage system (200) comprises an induced draft fan (210), a five-way pipe (220), a solenoid valve (230), and a solenoid valve controller (240) which are connected in sequence; The five-way pipe (220) has an inlet and two pairs of outlets arranged opposite to each other, and each outlet is connected to a solenoid valve (230); The solenoid valve controller (240) comprises: a front-end solenoid valve controller (241) and a rear-end solenoid valve controller (243); The two electromagnetic valves (230) arranged opposite to each other are respectively controlled by a front electromagnetic valve controller (241) or a rear electromagnetic valve controller (243).

4. The boiler waste heat composite utilization system according to claim 3 is characterized in that: The air preheating system (300) comprises: a heating system (310), a heat transfer medium mechanism (320), a heat exchanger (330), and a cold air heater (340) which are connected in sequence.

5. The boiler waste heat composite utilization system according to claim 4 is characterized in that: The lignite drying system (400) is a drum dryer (410); The drum dryer (410) is provided with a feed port (420) at the top, a discharge port (430) at the bottom, and a smoke inlet (440) at the side wall, and the smoke inlet (440) is connected to a five-way pipe (220) in the smoke guide and drainage system (200) through a pipeline.

6. The boiler waste heat composite utilization system according to claim 5, characterized in that: The hot water network heating system (500) comprises an anti-corrosion tubular heat exchanger (510) and a water heating system hot network connector (520) which are connected in sequence; The other end of the water heating system heat network connector (520) is connected to any one of the heat network circulating water circuit of the heating plant or the heat network circulating water circuit of the plant area water heating system.

7. The boiler waste heat composite utilization system according to claim 6, characterized in that: The solenoid valve controller (240) further includes: a mid-end solenoid valve controller (242); The front-end solenoid valve controller (241) and the rear-end solenoid valve controller (243) are connected via the middle-end solenoid valve controller (242).

8. The boiler waste heat composite utilization system according to claim 7, characterized in that: The condensed water heating system (600) comprises a flue gas heat recovery heater (610) and a water-to-water heat exchanger (620) which are connected in sequence.

9. A method for composite utilization of boiler waste heat, characterized in that: The boiler waste heat composite utilization system according to claim 8 for realizing the method comprises the following steps: The flue gas generated by the boiler enters the desulfurization tower for desulfurization treatment; The desulfurized flue gas enters the boiler flue gas desulfurization system (100) for further treatment to remove the remaining sulfur components in the flue gas; The treated flue gas is diverted through a flue gas guide and drainage system (200) and input into an air preheating system (300), a lignite drying system (400), a hot water network heating system (500), and a condensate heating system (600); The air preheating system (300) and the lignite drying system (400) are controlled synchronously; and the hot water network heating system (500) and the condensed water heating system (600) are controlled synchronously.

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