System for drying sludge by using low-grade waste heat

Abstract

The utility model discloses a system for drying sludge by utilizing low-grade waste heat, which comprises an industrial process and hot water system, a water source hot air heat pump system comprises an evaporator, a compressor, a condenser and an expansion valve, a sludge drying system comprises a drying oven, and a conveying mesh belt and a drying air system are arranged in the drying oven. According to the utility model, heat energy of 35-60 DEG C waste heat water output by an industrial process waste heat system is utilized by the water source hot air heat pump system to cool the waste heat water to 20-35 DEG C, and drying air at 60-120 DEG C is generated by the heat energy compressor under the assistance of electric energy which is about 15-30% of heating capacity, so that the use of a cooling tower system is avoided, and the original process is not influenced; the sustainable utilization of the low-grade waste heat water which needs to be discharged originally is realized; waste heat resources are effectively utilized through the sludge drying system, efficient drying treatment of the sludge is achieved, meanwhile, a large amount of sludge treatment cost can be saved, and cost is saved for enterprises.

Description

Technical Field

[0001] The utility model relates to the technical field of sludge drying, in particular to a system for drying sludge by utilizing low-grade waste heat. Background Art

[0002] Low-grade waste heat refers to waste heat resources with low temperature and low energy density generated in the industrial production process. This type of waste heat usually comes from various waste gases, waste water and waste heat in industrial production, and its temperature is generally below 100°C. Although the temperature is not high, low-grade waste heat still contains potential energy. Effective use of this waste heat resource can play an important role in energy conservation and emission reduction.

[0003] In current industrial production processes, open-air cooling towers are usually used to treat waste water. The waste water is directly introduced into the cooling tower, where it is cooled and then re-delivered to the production process, forming a continuous heat dissipation cycle to ensure that production equipment and materials can maintain normal operation. However, in this process, the energy of the waste water is all dissipated into the environment. Although the energy grade of the waste heat is low, its amount is huge. If it is allowed to dissipate into the environment, it will lead to a large waste of energy. Utility Model Content

[0004] The purpose of the utility model is to solve the above problems and provide a system for drying sludge by utilizing low-grade waste heat.

[0005] In order to achieve the above-mentioned purpose, the utility model specifically adopts the following technical solutions, including:

[0006] Industrial process and hot water system, the industrial process and hot water system is used to output and receive waste hot water;

[0007] A water-source hot air heat pump system, the water-source hot air heat pump system comprising an evaporator, a compressor and a condenser, the water-source hot air heat pump system absorbs the heat of waste hot water through the evaporator in cooperation with the compressor, and the water-source hot air heat pump system releases the absorbed heat through the condenser in cooperation with the compressor to form a drying air with a higher temperature;

[0008] The sludge drying system comprises an oven, the oven is provided with a conveyor mesh belt and a drying air system, the conveyor mesh belt cooperates with the drying air system to complete the wet heat exchange process of the sludge.

[0009] As a further description of the above technical solution, the evaporator is a shell and tube evaporator, the compressor is a thermal energy compressor, and the condenser is a fin condenser.

[0010] As a further description of the above technical solution, the evaporator, the compressor and the condenser are connected in sequence through pipelines, and the circulation flow of the refrigerant is completed through the pipelines.

[0011] As a further description of the above technical solution, an expansion valve is connected between the shell and tube evaporator and the fin condenser, and the expansion valve controls the valve flow and evaporation pressure through the change of superheat at the end of the evaporator.

[0012] As a further description of the above technical solution, a feeding system is provided on one side above the oven, and a discharging system is provided on the other side below the oven. The feeding system and the discharging system cooperate with the conveyor belt to complete the wet heat exchange process of the sludge.

[0013] As a further description of the above technical solution, the drying air system includes a drying air inlet, a drying air outlet, a dehumidification air outlet, a fresh air outlet and an air duct. The drying air inlet, the drying air outlet, the dehumidification air outlet and the fresh air outlet are connected to the oven through the air duct. The drying air system cooperates with the conveyor belt to complete the moisture and heat exchange between the drying air and the sludge.

[0014] As a further description of the above technical solution, the drying air inlet is arranged above the oven, and the drying air inlet is used to transport the high-temperature drying air generated by the condenser.

[0015] As a further description of the above technical solution, the drying air outlet is arranged below the oven, and the drying air outlet is used to output low-temperature drying air to the condenser.

[0016] As a further description of the above technical solution, the dehumidification air outlet is arranged on one side of the drying air outlet, and the dehumidification air outlet is used to discharge part of the high-humidity drying air and adjust the humidity of the drying air transported back to the condenser.

[0017] As a further description of the above technical solution, the fresh air inlet is arranged on one side of the drying air outlet, and the fresh air inlet is used to introduce low-humidity fresh air to maintain a balance between moisture content and air volume.

[0018] The beneficial effects of the utility model are as follows:

[0019] 1. The utility model utilizes the heat energy of 35-60℃ waste hot water output from the industrial process waste heat system through a water source hot air heat pump system, cools it down to 20-35℃, and generates 60-120℃ drying air with the assistance of electric energy of about 15-30% of the heating capacity through a thermal energy compressor. The system can also avoid the use of a cooling tower system and will not affect the original process, thus realizing the sustainable utilization of low-grade waste hot water that originally needs to be discharged;

[0020] 2. The utility model dries the sludge in the oven through the sludge drying system. After partial dehumidification and the introduction of low-humidity fresh air at about 35°C, a low-temperature and low-humidity mixed air at about 35-60°C is formed, and then the hot side of the water source hot air heat pump system is heated to 60-120°C. The sludge then enters the sludge drying system for further drying, forming a circulation process. This system has low energy consumption and realizes efficient drying of the sludge by effectively utilizing waste heat resources. At the same time, it can save a lot of sludge treatment costs, saving costs for the enterprise.

[0021] In order to more clearly illustrate the structural features and functions of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the system structure of the utility model.

[0023] Reference numerals:

[0024] 1. Industrial process and hot water system; 2. Water source hot air heat pump system; 21. Evaporator; 22. Compressor; 23. Condenser; 24. Expansion valve; 3. Sludge drying system; 31. Oven; 32. Conveyor belt; 33. Drying air system; 331. Drying air inlet; 332. Drying air outlet; 333. Dehumidification air outlet; 334. Fresh air outlet; 335. Air duct; 34. Feeding system; 35. Discharging system. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present utility model clearer, the technical solution in the embodiments of the present utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the present utility model.

[0026] like Figure 1 As shown, in one embodiment, a system for drying sludge using low-grade waste heat includes: an industrial process and hot water system 1, a water source hot air heat pump system 2 and a sludge drying system 3. The industrial process and hot water system is used to output and receive waste hot water, and the water source hot air heat pump system 2 absorbs heat energy in the waste hot water through the synergistic effect of the evaporator 21 and the compressor 22. Subsequently, the water source hot air heat pump system 2 releases the absorbed heat energy through the condenser 23 and the compressor 22 to form a drying air with a higher temperature.

[0027] Specifically, the water source hot air heat pump system 2 utilizes 35-60°C waste hot water in the industrial process waste heat system, cools it down to 20-35°C, and generates 60-120°C drying air with the assistance of a small amount of electric energy through the thermal compressor 22. The use of this system can not only efficiently utilize low-grade waste hot water resources, but also avoid the use of a cooling tower system, and has no negative impact on the original process.

[0028] like Figure 1 As shown, in this embodiment, the water source hot air heat pump system 2 includes an evaporator 21, a compressor 22 and a condenser 23. The evaporator 21, the compressor 22 and the condenser 23 are connected in sequence through pipelines to complete the circulation of the refrigerant; an expansion valve 24 is installed between the shell and tube evaporator 21 and the finned condenser 23, and the expansion valve 24 controls the flow rate and evaporation pressure of the valve by monitoring the change of superheat at the end of the evaporator 21.

[0029] Specifically, the evaporator 21 is a shell and tube evaporator 21 , the compressor 22 is a thermal energy compressor 22 , and the condenser 23 is a fin condenser 23 .

[0030] like Figure 1 As shown, in this embodiment, the sludge drying system 3 includes an oven 31, and the oven 31 is provided with a conveyor mesh belt 32 and a drying air system 33. The conveyor mesh belt 32 cooperates with the drying air system 33 to complete the wet heat exchange process of the sludge. Among them, a feeding system 34 is provided on the upper side of the oven 31 to transport the sludge to be treated into the oven 31; and a discharging system 35 is provided on the other side below the oven 31 to discharge the sludge that has been dried. The feeding system 34 and the discharging system 35 work together with the conveyor mesh belt 32 to ensure that the sludge is fully exposed to the drying air in the oven 31.

[0031] Furthermore, the drying air system 33 includes a drying air inlet 331, a drying air outlet 332, a moisture removal air outlet 333, a fresh air outlet 334 and an air duct 335, and is connected to the oven 31 via the air duct 335. The drying air system 33 cooperates with the conveyor belt 32 to complete the moisture and heat exchange between the drying air and the sludge.

[0032] Specifically, after partial dehumidification and the introduction of low-humidity fresh air at about 35°C, a low-temperature and low-humidity mixed air at about 35-60°C is formed, and then heated to 60-120°C on the hot side of the water source hot air heat pump system 2, and then enters the sludge drying system 3 to further dry the sludge, forming a circulation process. This system has low energy consumption and achieves efficient drying treatment of the sludge by effectively utilizing waste heat resources. At the same time, it can save a lot of sludge treatment costs, saving costs for the enterprise.

[0033] Specifically, the drying air inlet 331 is arranged above the drying oven 31, and is used to transport the high-temperature drying air generated by the condenser 23; the drying air outlet 332 is arranged below the drying oven 31, and is used to output the low-temperature drying air to the condenser 23; the dehumidification air outlet 333 is arranged at one side of the drying air outlet 332, and is used to discharge part of the high-humidity drying air and adjust the humidity of the drying air transported back to the condenser 23. The fresh air outlet 334 is arranged at one side of the drying air outlet 332, and is used to introduce low-humidity fresh air to maintain a balance between moisture content and air volume.

[0034] Working principle:

[0035] (1) When a small amount of electric energy W is input to the heat pump compressor 22, the shell and tube evaporator 21 can absorb the heat of waste hot water at about 35-60°C and output cooling water at about 20-35°C. The absorbed heat can reach about 3 times W, denoted as Qo, and the small amount of electric energy W input and the absorbed heat Qo are released together on the side of the finned condenser 23. The released heat is Qo+W, which is about 4 times W, denoted as Qk, and the wind at 35-60°C can be heated to 60-120°C.

[0036] (2) Sludge with a moisture content of 70-80% can enter the drying oven 31 through the feeding system 34, fall onto the conveyor mesh belt 32, and run on the conveyor mesh belt 32 for a certain period of time before being discharged from the discharging system 35. The drying air at 60-120°C can enter the drying oven 31 through the drying air inlet 331, contact the sludge on the conveyor belt, and perform heat and moisture exchange, so that the moisture content of the discharging system 35 reaches about 10-30%. After drying the sludge, the temperature of the drying air will change from 60-120°C to 40- 70℃, the temperature drops and the moisture content increases. At this time, in order to make the drying air return to its original moisture content state, a part of the high-humidity drying air needs to be discharged from the dehumidification air outlet 333, and low-humidity fresh air needs to be introduced to maintain the balance of moisture content and air volume. The introduced fresh air will become 35-60℃ after mixing with the undischarged drying air. At this time, this part of the air will be heated by the finned condenser 23 of the water source hot air heat pump system 2, and then return to 60-120℃, forming a cycle and maintaining the balance of the three major systems.

[0037] 400m 3 For example, the 35-45℃ waste water of / h becomes 25-35℃ after passing through the shell and tube evaporator 21 of the water source hot air heat pump system 2, and the absorbed heat is about 4650kw, that is, Qo=4650kw, the electric power W≈1550kw, and the released heat Qk≈6200kw, which can make the sludge dewatering (weight reduction)≈150 tons / day. Calculated at an electricity fee of 0.8 yuan / kWh, the daily power consumption is≈

[0038] 1550*24=37200kWh, the electricity cost for one day ≈ 37200*0.8=29760 yuan / day; the sludge treatment cost is calculated at 1000 yuan / ton, the cost saved for one day is 150*1000=150000 yuan / day, which means more than 100,000 yuan can be saved every day.

[0039] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for drying sludge using low-grade waste heat, characterized in that: include: An industrial process and hot water system (1), the industrial process and hot water system (1) being used to output and receive waste hot water; A water source hot air heat pump system (2), the water source hot air heat pump system (2) comprising an evaporator (21), a compressor (22) and a condenser (23); the water source hot air heat pump system (2) absorbs heat from waste hot water through the evaporator (21) in cooperation with the compressor (22); and the water source hot air heat pump system (2) releases the absorbed heat through the condenser (23) in cooperation with the compressor (22) to form drying air with a relatively high temperature; A sludge drying system (3), the sludge drying system (3) comprising an oven (31), the oven (31) being provided with a conveyor mesh belt (32) and a drying air system (33), the conveyor mesh belt (32) cooperating with the drying air system (33) to complete the wet heat exchange process of the sludge.

2. The system for drying sludge using low-grade waste heat according to claim 1 is characterized in that: The evaporator (21) is a shell and tube evaporator (21), the compressor (22) is a thermal energy compressor (22), and the condenser (23) is a fin condenser (23).

3. The system for drying sludge using low-grade waste heat according to claim 1, characterized in that: The evaporator (21), the compressor (22) and the condenser (23) are connected in sequence through pipelines, and the circulation flow of the refrigerant is completed through the pipelines.

4. The system for drying sludge using low-grade waste heat according to claim 1, characterized in that: An expansion valve (24) is connected between the evaporator (21) and the condenser (23), and the expansion valve (24) controls valve flow and evaporation pressure through changes in superheat at the end of the evaporator (21).

5. The system for drying sludge using low-grade waste heat according to claim 1, characterized in that: A feeding system (34) is provided on one side above the drying oven (31), and a discharging system (35) is provided on the other side below the drying oven (31). The feeding system (34) and the discharging system (35) cooperate with the conveyor mesh belt (32) to complete the wet heat exchange process of the sludge.

6. The system for drying sludge using low-grade waste heat according to claim 1, characterized in that: The drying air system (33) includes a drying air inlet (331), a drying air outlet (332), a dehumidification air outlet (333), a fresh air outlet (334) and an air duct (335). The drying air inlet (331), the drying air outlet (332), the dehumidification air outlet (333) and the fresh air outlet (334) are connected to the oven (31) via the air duct (335). The drying air system (33) cooperates with the conveyor belt (32) to complete the heat and moisture exchange between the drying air and the sludge.

7. The system for drying sludge using low-grade waste heat according to claim 6, characterized in that: The drying air inlet (331) is arranged above the drying oven (31), and the drying air inlet (331) is used to convey the high-temperature drying air generated by the condenser (23).

8. The system for drying sludge using low-grade waste heat according to claim 6, characterized in that: The drying air outlet (332) is arranged below the drying oven (31), and the drying air outlet (332) is used to output low-temperature drying air to the condenser (23).

9. The system for drying sludge using low-grade waste heat according to claim 6, characterized in that: The dehumidification air outlet (333) is arranged on one side of the drying air outlet (332), and the dehumidification air outlet (333) is used to discharge the drying air with high humidity and adjust the humidity of the drying air transported back to the condenser (23).

10. The system for drying sludge using low-grade waste heat according to claim 6, characterized in that: The fresh air inlet (334) is arranged on one side of the drying air outlet (332), and the fresh air inlet (334) is used to introduce low-humidity fresh air to maintain a balance between moisture content and air volume.

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