Energy-saving, emission-reducing and carbon-reducing device for recovering waste heat by using coal-fired boiler system

Abstract

According to the energy-saving, emission-reducing and carbon-reducing device for recovering waste heat by using the coal-fired boiler system, a heat conveying module comprises a desulfurizing tower 1 and a slurry circulating pump 2, and a heat exchange module comprises a phase change heat exchanger 3 and a desalting water pump 4; the bottom of the desulfurizing tower 1 is a slurry heat source area 11, the bottom of the slurry heat source area 11 is communicated with a slurry circulating pump 2 through a slurry outlet pipe 12, a rear path of the slurry circulating pump 2 is communicated with a phase change heat exchanger 3 through a slurry outlet pump pipe 21, and a rear path of the bottom of the phase change heat exchanger 3 is communicated with a spraying pipe 5 located in the top of the desulfurizing tower 1 through a spraying pipeline 31; the desalted water pump 4 is communicated with the phase change heat exchanger 3 through a desalted water inlet pipe 41, and the rear path of the top of the phase change heat exchanger 3 is communicated with a boiler water supplementing pipeline. According to the system, the waste heat in the system is recovered by fusing the resources of the coal-fired boiler system, other equipment such as a heater does not need to be consumed, and the purposes of energy conservation, emission reduction and carbon reduction are achieved.

Description

Technical Field

[0001] This utility model relates to the field of energy conservation, emission reduction and carbon reduction technology, and in particular to an energy conservation, emission reduction and carbon reduction device that utilizes waste heat recovery from a coal-fired boiler system. Background Technology

[0002] The large-scale application of coal-fired power has provided energy security for economic and social development, but it has also posed challenges to energy conservation, emission reduction, carbon reduction, and environmental governance. To reduce environmental pollution caused by coal combustion, flue gas treatment of coal-fired boilers is necessary. A common flue gas treatment process is the limestone-gypsum wet desulfurization process. The basic principle of this process is as follows: high-temperature raw flue gas (120℃-150℃) enters the desulfurization tower and comes into counter-current contact with the desulfurization slurry sprayed down. After being washed by the absorbent, SO2 and other substances in the flue gas are removed, and the flue gas temperature drops to around 50℃ before being discharged through the chimney. During the flue gas treatment process, most of the residual heat in the flue gas is exchanged with the desulfurization slurry. Water in the slurry is vaporized and enters the flue gas, causing the flue gas temperature to decrease while the water vapor increases, ultimately being discharged into the atmosphere.

[0003] The above analysis shows that the waste heat from the flue gas treatment process is not being effectively recovered and utilized. Therefore, effectively recovering waste heat from exhaust gas has become an urgent problem to be solved. Utility Model Content

[0004] To address the problems existing in the prior art, this utility model provides an energy-saving, emission-reducing, and carbon-reducing device that recovers waste heat from a coal-fired boiler system. It utilizes the heat from the desulfurization tower slurry, which is then heated by a phase-change heat exchanger before entering the boiler water system. This achieves the goal of energy saving, emission reduction, and carbon reduction in the boiler system, thereby reducing the amount of coal used in subsequent boiler combustion.

[0005] The technical solution adopted by this utility model to solve its technical problem is:

[0006] An energy-saving, emission-reducing, and carbon-reducing device for recovering waste heat from a coal-fired boiler system comprises a heat transfer module and a heat exchange module. The heat transfer module includes a desulfurization tower 1 and a slurry circulation pump 2, and the heat exchange module includes a phase changer 3 and a demineralized water pump 4. The bottom of the desulfurization tower 1 is a slurry heat source zone 11, and the bottom of the slurry heat source zone 11 is connected to the slurry circulation pump 2 via a slurry outlet pipe 12. The downstream path of the slurry circulation pump 2 is connected to the phase changer 3 via a slurry outlet pump pipe 21, and the downstream path of the bottom of the phase changer 3 is connected to a spray pipe 5 located inside the top of the desulfurization tower 1 via a spray pipe 31. The demineralized water pump 4 is connected to the phase changer 3 via a demineralized water inlet pipe 41, and the downstream path of the top of the phase changer 3 is connected to a boiler makeup water pipe.

[0007] This utility model also has the following additional technical features:

[0008] As a further specific optimization of the technical solution of this utility model: the phase change heat exchanger 3 includes a phase change heat exchanger hot end 3-2 and a phase change heat exchanger cold end 3-6; the phase change heat exchanger hot end 3-2 includes a slurry inlet 3-1 and a slurry outlet 3-4; the phase change heat exchanger cold end 3-6 includes a cold water inlet 3-5, an exhaust outlet 3-7 and a hot water outlet 3-3; wherein: the slurry inlet 3-1 is connected to the slurry outlet pipe 21 of the slurry circulation pump 2; the slurry outlet 3-4 is connected to the spray pipe 31 of the heat exchanger 3; the cold water inlet 3-5 is connected to the demineralized water inlet pipe 41 of the demineralized water pump 4; and the hot water outlet 3-3 is connected to the boiler makeup water pipe.

[0009] As a further specific optimization of the technical solution of this utility model: a pressure relief valve is installed on the exhaust outlet 3-7.

[0010] As a further specific optimization of the technical solution of this utility model: the slurry circulation pump 2 is also provided with a return pipe 22, which is connected to the spray pipe 31.

[0011] As a further specific optimization of the technical solution of this utility model: the phase change heat exchanger 3 is arranged between the slurry circulation pump 2 and the demineralized water pump 4.

[0012] As a further specific optimization of the technical solution of this utility model: the model of the slurry circulation pump 2 is...

[0013] JLYXH-001; Phase change heat exchanger 3 is model JLYHR-001; Demineralized water pump 4 is model JLYHR-001.

[0014] JLYCY-001.

[0015] Compared with the prior art, the advantages of this utility model are:

[0016] This invention integrates the resources of the coal-fired boiler system to recover waste heat without consuming other equipment such as heaters. It uses the heat from the circulating slurry in the desulfurization tower as a consumable, heating the demineralized water via a phase change heater, thereby increasing the temperature of the demineralized water and reducing the amount of coal burned in the boiler, achieving energy conservation, emission reduction, and carbon reduction. Simultaneously, the slurry first enters the phase change heat exchanger 3 and then the spray layer, achieving slurry heat exchange and spraying without the need for a dedicated pump, thus achieving energy conservation, emission reduction, and carbon reduction. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is a schematic diagram of the structure of this utility model;

[0019] Explanation of reference numerals in the attached diagram: 1-Slurry heat source zone; 2-Slurry circulation pump; 3-Phase changer; 4-Demineralized water pump. 3-1-Slurry inlet; 3-2-Hot end of phase changer; 3-3-Hot water outlet; 3-4-Slurry outlet; 3-5-Cold water inlet; 3-6-Cold end of phase changer; 3-7-Exhaust outlet. Detailed Implementation

[0020] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings.

[0021] An energy-saving, emission-reducing, and carbon-reducing device that utilizes waste heat recovery from a coal-fired boiler system comprises a heat transfer module and a heat exchange module. The heat transfer module includes a desulfurization tower 1 and a slurry circulation pump 2, and the heat exchange module includes a phase change heat exchanger 3 and a demineralized water pump 4. The phase change heat exchanger 3 is arranged between the slurry circulation pump 2 and the demineralized water pump 4.

[0022] The model of slurry circulation pump 2 is JLYXH-001; the model of phase change heat exchanger 3 is JLYHR-001; and the model of demineralized water pump 4 is JLYCY-001.

[0023] The bottom of the desulfurization tower 1 is the slurry heat source zone 11. The bottom of the slurry heat source zone 11 is connected to the slurry circulation pump 2 through the slurry outlet pipe 12. The downstream path of the slurry circulation pump 2 is connected to the phase change heat exchanger 3 through the slurry outlet pump pipe 21. The downstream path of the slurry circulation pump 2 is also provided with a return pipe 22, which is connected to the spray pipe 31.

[0024] The bottom of the phase change heat exchanger 3 is connected to the spray pipe 5 located inside the top of the desulfurization tower 1 via the spray pipe 31; the demineralized water pump 4 is connected to the phase change heat exchanger 3 via the demineralized water inlet pipe 41, and the top of the phase change heat exchanger 3 is connected to the boiler makeup water pipe.

[0025] The phase change heat exchanger 3 includes a hot end 3-2 and a cold end 3-6. The hot end 3-2 includes a slurry inlet 3-1 and a slurry outlet 3-4. The cold end 3-6 includes a cold water inlet 3-5, an exhaust outlet 3-7, and a hot water outlet 3-3. The slurry inlet 3-1 is connected to the slurry outlet pipe 21 of the slurry circulation pump 2. The slurry outlet 3-4 is connected to the spray pipe 31 of the heat exchanger 3. The cold water inlet 3-5 is connected to the demineralized water inlet pipe 41 of the demineralized water pump 4. The hot water outlet 3-3 is connected to the boiler makeup water pipe. A pressure relief valve is installed on the exhaust outlet 3-7.

[0026] The working principle of an energy-saving, emission-reducing, and carbon-reducing device that recovers waste heat from a coal-fired boiler system:

[0027] As attached Figure 1As shown, boiler flue gas passes through desulfurization tower 1, where heat is retained in the slurry via circulating spraying. The slurry is then pumped into phase change heat exchanger 3 by slurry circulation pump 2, where it comes into contact with demineralized water supplied by demineralized water pump 4. The heated demineralized water reaches 50°C. Taking advantage of the characteristic that the boiling point of water decreases with decreasing ambient pressure, a negative pressure environment of -13.0 kPa is artificially created in the circulation pipe of the heat transfer medium (demineralized water). This causes the water above 50°C to flash evaporate, generating negative pressure steam that carries the latent heat of vaporization to the condenser for condensation and heat release into the low-temperature medium. The heat transfer medium circulates within the closed negative pressure circulation pipe, undergoing a physical reaction of heating-evaporation-condensation-heating. The heated demineralized water, reaching 50°C, then enters the boiler water system, thus achieving the goals of waste heat recovery, energy saving, emission reduction, and carbon reduction.

[0028] Application Analysis of an Energy-Saving, Emission-Reducing, and Carbon-Reducing Device Utilizing Waste Heat Recovery from a Coal-Fired Boiler System:

[0029] I. Heat Sources of Desulfurization Slurry

[0030] 1. Source of heat in slurry

[0031] The boiler is a 90t / h circulating fluidized bed boiler with a rated evaporation capacity of 90t / h. Based on the current operating conditions: primary air flow rate is 51439 Nm³ / h; secondary air flow rate is 26684 Nm³ / h; demineralized water temperature is 20℃; and the current average flue gas temperature is approximately 135℃. After passing through the desulfurization tower, the flue gas is discharged from the chimney at an average temperature of 55℃.

[0032] 2. Slurry heat recovery

[0033] A phase-change heat exchanger is used to achieve heat exchange between the slurry and the heat transfer medium (demineralized water), and between the heat transfer medium and industrial water. The heat transfer medium (demineralized water) reaches 50°C after the slurry is heated. Taking advantage of the characteristic that the boiling point of water decreases with decreasing ambient pressure, a negative pressure environment of -13.0 kPa is artificially created in the circulation pipe of the heat transfer medium (demineralized water). This causes the water above 50°C to flash evaporate, generating negative pressure steam that carries the latent heat of vaporization and is transported to the condenser for condensation and heat release to the low-temperature medium. The heat transfer medium circulates within the closed negative pressure circulation pipe, undergoing a heating-evaporation-condensation-heating physical reaction, thus achieving clean, efficient, and low-cost recovery of the slurry's waste heat. Because the slurry has an acidic pH, both the shell and tube sides of the heat exchanger are made of carbon steel with an enamel exterior, and both the shell and tube sides of the condenser are made of carbon steel.

[0034] Phase change heat exchangers have the following characteristics: long service life, strong corrosion resistance of the enamel material, high pressure resistance, and high equipment lifespan. They also offer high heat exchange efficiency, a small footprint, stable operation (heat exchange is achieved as long as the slurry pump is running), and low energy consumption (the slurry first enters the heat exchanger and then the spray layer, eliminating the need for a dedicated pump for both heat exchange and spraying).

[0035] 2. Heat can be recovered from the slurry.

[0036] Using the boiler's annual average flue gas temperature of 130℃ and slurry temperature of 55℃ as the starting point, and considering a flue gas temperature drop of 75℃ within this range, the recoverable temperature per hour is:

[0037] In the formula, Vg = 90000 Nm 3 / h is the flue gas flow rate; ρg = 1.295 kg / Nm³ 3 , where Cpg is the density of the flue gas;

[0038] 1.12 kJ / (kg℃) is the specific heat of the flue gas; ΔT represents the temperature difference between the flue gas before and after the exhaust gas. The heat retention coefficient of the equipment is taken as 0.98.

[0039] Q J =2665.11 × 860 × 4.18 / 10 6 =9.58GJ; where 2665.11kW is the kilowatts of recovered heat; 860 [kcal / (kWh)] is the unit conversion factor; 4.18 [kJ / kcal] is the unit conversion factor.

[0040] II. Energy Absorption

[0041] 1. Energy required for heating raw water

[0042] During the winter heating season, assuming a boiler load of 60 t / h, the required raw water volume for water treatment is 60 * 1.6 = 96 t / h. The raw water temperature in winter is 5℃, requiring heating to 25℃-40℃, raising the temperature by at least 20℃. The required heat is: Q = 96 × 1000 × 20 × 4.18 ÷ 10 6 =8.02GJ.

[0043] 2. Heat exchanger area

[0044] Based on the same heat recovery project at Pingyuan Thermal Power Plant, the required heat exchanger area for our plant can be calculated. Pingyuan Thermal Power Plant has a boiler load of 350 t / h. After the raw water passes through a 721 m² heat exchanger, its temperature is increased by 10℃. The heat exchange capacity per m² per hour can be calculated as follows: Total heat recovered per hour: Q = 350 × 1000 × 10 × 4.18 ÷ 10 6 =14.63GJ; Heat exchange capacity per square meter per hour: 14.63÷721=0.02029GJ / ㎡.

[0045] The required heat exchanger area for our factory is 8.02 ÷ 0.02029 = 395.26㎡; the required condenser area is 300㎡.

[0046] III. Process Layout

[0047] 1. Install a phase change heat exchanger with a heat exchange area of ​​400㎡ and a condensation area of ​​300㎡ at the circulation pump of the No. 2 desulfurization tower. Set a bypass for the heat exchanger in the outlet pipeline of circulation pump A.

[0048] 2. A 50m³ / h flow rate water pipe is installed at the industrial water pipe location on the zero-meter floor of the boiler room. 3 The / h pipeline pump pumps water into the heat exchanger, and the water that has absorbed heat enters the raw water pipeline of the water treatment workshop.

[0049] The above detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

Claims

1. An energy-saving, emission-reducing, and carbon-reducing device for recovering waste heat from a coal-fired boiler system, characterized in that: It consists of a heat transfer module and a heat exchange module, wherein: the heat transfer module includes a desulfurization tower (1) and a slurry circulation pump (2), and the heat exchange module includes a phase change heat exchanger (3) and a demineralized water pump (4); the bottom of the desulfurization tower (1) is a slurry heat source area (11), the bottom of the slurry heat source area (11) is connected to the slurry circulation pump (2) through a slurry outlet pipe (12), the downstream path of the slurry circulation pump (2) is connected to the phase change heat exchanger (3) through a slurry outlet pump pipe (21), and the downstream path of the bottom of the phase change heat exchanger (3) is connected to the spray pipe (5) located inside the top of the desulfurization tower (1) through a spray pipe (31); the demineralized water pump (4) is connected to the phase change heat exchanger (3) through a demineralized water inlet pipe (41), and the downstream path of the top of the phase change heat exchanger (3) is connected to the boiler makeup water pipe.

2. The energy-saving, emission-reducing, and carbon-reducing device for recovering waste heat from a coal-fired boiler system according to claim 1, characterized in that, The phase change heat exchanger (3) includes a phase change heat exchanger hot end (3-2) and a phase change heat exchanger cold end (3-6); the phase change heat exchanger hot end (3-2) includes a slurry inlet (3-1) and a slurry outlet (3-4); the phase change heat exchanger cold end (3-6) includes a cold water inlet (3-5), an exhaust outlet (3-7) and a hot water outlet (3-3); wherein: the slurry inlet (3-1) is connected to the slurry outlet pipe (21) of the slurry circulation pump (2); the slurry outlet (3-4) is connected to the spray pipe (31) of the heat exchanger (3); the cold water inlet (3-5) is connected to the demineralized water inlet pipe (41) of the demineralized water pump (4); and the hot water outlet (3-3) is connected to the boiler makeup water pipe.

3. The energy-saving, emission-reducing, and carbon-reducing device for recovering waste heat from a coal-fired boiler system according to claim 1, characterized in that, A pressure relief valve is installed on the exhaust outlet (3-7).

4. The energy-saving, emission-reducing, and carbon-reducing device for recovering waste heat from a coal-fired boiler system according to claim 1, characterized in that, The slurry circulation pump (2) is also provided with a return pipe (22), which is connected to the spray pipe (31).

5. The energy-saving, emission-reducing, and carbon-reducing device for recovering waste heat from a coal-fired boiler system according to claim 1, characterized in that, The phase change heat exchanger (3) is arranged between the slurry circulation pump (2) and the demineralized water pump (4).

6. The energy-saving, emission-reducing, and carbon-reducing device for recovering waste heat from a coal-fired boiler system according to claim 1, characterized in that, The model of the slurry circulation pump (2) is JLYXH-001; the model of the phase change heat exchanger (3) is JLYHR-001; and the model of the demineralized water pump (4) is JLYCY-001.

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