A waste heat recovery system for low-temperature waste heat power generation in a cement clinker production line (ORC)

Abstract

The utility model provides a waste heat recovery system for low-temperature waste heat power generation of a cement clinker production line (ORC), wherein the recovery device comprises a kiln head waste gas circulation unit and a kiln tail waste gas recovery unit, wherein the kiln head waste gas circulation unit is composed of a grate cooler, a kiln head thermal oil heat exchanger, a kiln head dust collector, a head exhaust fan, and a cooling fan; the kiln tail waste gas recovery unit is composed of a kiln tail preheater, a kiln tail thermal oil heat exchanger, a high-temperature fan, a kiln tail dust collector, an induced draft fan, and a kiln tail chimney; the device optimizes the waste gas waste heat recovery device of the entire ORC waste heat power generation device through the kiln head waste gas circulation unit and the kiln tail waste gas recovery unit, the device resistance is reduced, the fan power consumption is reduced, the waste heat of the waste gas is recycled, the waste heat of the waste gas is fully utilized, the power generation of the system is greatly improved, the waste gas at the kiln head is "zero" discharged, and the production needs of energy saving and consumption reduction are met. In addition, the device runs more safely and efficiently.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature waste heat power generation of an organic Rankine cycle (ORC) of a cement clinker production line, and in particular to a waste heat recovery system for low-temperature waste heat power generation of a cement clinker production line (ORC). Background Art

[0002] Organic Rankine cycle (ORC) power generation technology has more advantages than steam Rankine cycle (SRC) in the field of low-temperature flue gas waste heat utilization, especially when the waste gas temperature is 250℃~350℃. SRC does not have power generation advantages, and ORC low-temperature waste heat power generation technology is usually preferred.

[0003] In cement clinker production lines, the exhaust gas outlet temperature of the grate cooler is usually 250℃~350℃, and the flue gas temperature is generally 270℃~300℃ during normal operation. In order to avoid the adverse effects of low-temperature flue gas on power generation technology, the cement clinker production line steam Rankine cycle (SRC) low-temperature waste heat power generation project usually adopts the method of taking air from the middle of the grate cooler, that is, opening a hole in the middle of the grate cooler as the air intake of the boiler. However, the air intake in the middle of the grate cooler is usually limited by the structure of the grate cooler, the layout of the cooling fan, and the beams and columns of the kiln head building on site, resulting in improper positioning of some middle air intakes, small air intake or excessively high air temperature, resulting in low waste heat power generation. Therefore, some cement production lines have adopted ORC waste heat power generation technology. However, in the currently operating cement line ORC waste heat power generation projects, the exhaust temperature of the kiln head thermal oil heat exchanger is generally around 100-130℃. This part of the heat is not used, and is discharged to the atmosphere through the head exhaust fan and the kiln head chimney, causing a huge waste of heat resources and environmental thermal pollution. In addition, in some operating cement kiln ORC waste heat power generation, the kiln head thermal oil heat exchanger adopts the middle air intake method, the temperature is high and the flue gas contains cement clinker particles with high hardness, the heat exchange tube is more likely to wear and leak, and there are certain safety hazards.

[0004] With the energy-saving and emission-reduction technical transformation of cement production lines, six-stage preheaters are generally used in cement production line kiln tail preheaters. The flue gas temperature at the outlet of the six-stage preheater is usually 250-280℃. This flue gas temperature level is more suitable for ORC low-temperature waste heat power generation. The traditional kiln tail thermal oil heat exchanger is often used as a bypass for the downcomer of the kiln tail preheater. The downcomer is the main pipe with a larger diameter. In actual operation, the bypass valve on the downcomer is in a normally closed state, and the bypass valve is only opened under certain working conditions, resulting in a large consumption of pipes due to the large diameter downcomer.

[0005] Therefore, in the existing cement line ORC waste heat power generation technology, there is an urgent need for an equipment optimization solution that can reduce the heat consumption of the device, alleviate thermal pollution and environmental pollution, optimize the design of the pipeline device, and reduce investment. Utility Model Content

[0006] In view of the difficulties in the existing technology, the utility model provides a waste heat recovery system for low-temperature waste heat power generation of a cement clinker production line (ORC). The system optimizes the waste gas and waste heat recovery device of the entire ORC waste heat power generation device through a kiln head waste gas circulation unit and a kiln tail waste gas recovery unit. The resistance of the device is reduced, the power consumption of the fan is reduced, the waste heat of the waste gas is recycled and fully utilized, the power generation of the system is greatly improved, the waste gas at the kiln head is achieved "zero" emission, and the production needs of energy saving and consumption reduction are met. In addition, the operation of the device is safer and more efficient.

[0007] In order to solve the existing technical problems, the utility model adopts the following technical solutions:

[0008] A waste heat recovery system for low-temperature waste heat power generation of a cement clinker production line (ORC), the recovery system comprising a kiln head waste gas circulation unit and a kiln tail waste gas recovery unit, the kiln head waste gas circulation unit is composed of a grate cooler, a kiln head thermal oil heat exchanger, a kiln head dust collector, a head exhaust fan, and a cooling fan; wherein: the input end of the kiln head thermal oil heat exchanger is connected to the exhaust port of the grate cooler through a first valve; its output end is connected to the head exhaust fan through a second valve and the kiln head dust collector in turn; the output end of the head exhaust fan is connected through a cooling fan;

[0009] The kiln tail exhaust gas recovery unit is composed of a kiln tail preheater, a kiln tail heat transfer oil heat exchanger, a high temperature fan, a kiln tail dust collector, an induced draft fan, and a kiln tail chimney; wherein: the input end of the kiln tail heat transfer oil heat exchanger is connected to the kiln tail preheater through a third valve; its output end is connected to the high temperature fan through a fourth valve; the output end of the high temperature fan is connected to the kiln tail chimney through the kiln tail dust collector and the induced draft fan in sequence;

[0010] A bypass pipeline is connected in parallel between the two ends of the kiln tail heat transfer oil heat exchanger; wherein:

[0011] The cooling fan sends the circulating air into the grate cooler, which exchanges heat with the cement clinker and then enters the kiln head thermal oil heat exchanger from its exhaust gas outlet; the kiln head thermal oil heat exchanger heats the thermal oil inside it according to the exhaust gas sent in to provide heat to the waste heat power generation device; at the same time, the kiln head thermal oil heat exchanger sends the low-temperature flue gas of 100-130°C after heat exchange to the kiln head dust collector; the head exhaust fan receives the flue gas filtered by the kiln head dust collector and leads it back to the cooling fan to complete the closed circulation of the exhaust gas.

[0012] Furthermore, the bypass pipeline adopts a small diameter pipeline with a flow capacity of 50% to 60%, and a fifth valve is also arranged on it.

[0013] Beneficial Effects

[0014] Compared with the traditional technical solution, the beneficial effects brought by the utility model are:

[0015] Compared with the prior art, the utility model optimizes the design of the waste heat recovery and utilization device at the kiln head and kiln tail of the ORC waste heat power generation device of the cement production line. Regarding the optimized design of the waste heat recovery device for the kiln head exhaust gas: the flue gas temperature entering the kiln head thermal oil heat exchanger can be increased by 50°C to 70°C, which can greatly improve the thermal efficiency of ORC waste heat power generation, thereby greatly increasing the waste heat power generation. Since the grate cooler exhaust gas is recycled, the device is completely closed-loop, and the kiln head exhaust gas is truly "zero" emission. In addition, the kiln head thermal oil heat exchanger uses the grate cooler exhaust gas outlet as the air intake, and the flue gas temperature is relatively low, which is conducive to the safe and stable operation of the kiln head thermal oil heat exchanger, and also avoids some disadvantages of opening a hole in the middle of the grate cooler as the air intake.

[0016] Regarding the optimized design of the waste heat recovery device for kiln tail exhaust gas: the kiln tail thermal oil heat exchanger is no longer used as a bypass of the kiln tail preheater, but as the main path of the kiln tail preheater, and a bypass pipe with a small flow capacity is used as a bypass. This makes the air flow of the kiln tail thermal oil heat exchanger smoother, reduces resistance, and reduces the power consumption of the high-temperature fan; at the same time, the small-diameter bypass pipe consumes less pipe material and reduces investment.

[0017] The exhaust air volume of the cement line kiln head can be 100% recycled, which is expected to increase the power generation by 8-11kwh / tc l, and the waste heat power generation effect is significant; it has achieved "zero" emission of waste gas from the kiln head, which is a revolutionary progress for waste heat power generation of cement clinker production line. The waste gas waste heat recovery device of the entire ORC waste heat power generation device has been optimized, with simple layout, convenient installation, smooth process flow, reduced device resistance, reduced fan power consumption, safer and more efficient device operation, and no need to invest too much cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural diagram of a low-temperature waste heat power generation and waste heat recovery system of a cement clinker production line (ORC) of the utility model.

[0019] Figure markings, 1-grate cooler, 2-kiln head thermal oil heat exchanger, 2a-first valve, 2b-second valve, 3-kiln head dust collector, 4-head exhaust fan, 5-cooling fan, 6-kiln head chimney, 7-kiln tail preheater, 8-kiln tail thermal oil heat exchanger, 8a-third utility model, 8b-fourth valve, 8c-fifth valve, 9-high temperature fan, 10-kiln tail dust collector, 11-induced draft fan, 12-kiln tail chimney, 13-bypass pipeline. DETAILED DESCRIPTION

[0020] The following is combined with Figure 1 The utility model is described as follows:

[0021] like Figure 1As shown, the utility model provides a waste heat recovery system for low-temperature waste heat power generation of a cement clinker production line (ORC), the recovery system comprising a kiln head waste gas circulation unit 101 and a kiln tail waste gas recovery unit 201, the kiln head waste gas circulation unit 101 is composed of a grate cooler 1, a kiln head thermal oil heat exchanger 2, a kiln head dust collector 3, a head exhaust fan 4, and a cooling fan 5; wherein: the input end of the kiln head thermal oil heat exchanger 2 is connected to the exhaust port of the grate cooler 1 through a first valve 2a; the output end of the kiln head thermal oil heat exchanger 2 is connected to the head exhaust fan 4 through a second valve 2b and the kiln head dust collector 3 in sequence; the output end of the head exhaust fan 4 is connected to the grate cooler 1 through a cooling fan; wherein:

[0022] The cooling fan 5 sends the circulating air into the grate cooler 1, and after heat exchange with the cement clinker, it enters the kiln head thermal oil heat exchanger 2 from its exhaust gas outlet; the kiln head thermal oil heat exchanger 2 heats the thermal oil inside it according to the exhaust gas sent in, and provides heat to the waste heat power generation device; at the same time, the kiln head thermal oil heat exchanger 2 sends the low-temperature flue gas of 100-130°C after heat exchange to the kiln head dust collector 3; the head exhaust fan 4 receives the flue gas filtered by the kiln head dust collector 3 and leads it back to the cooling fan to complete the closed circulation of the exhaust gas. In the utility model, the exhaust gas circulation unit at the kiln head provides the exhaust smoke of the kiln head thermal oil heat exchanger 2, which is dust-removed by the kiln head dust collector 3 and becomes clean circulating air with a certain temperature. The exhaust smoke is sent to the cooling fan 5 through the head exhaust fan 4 and then blown into the grate cooler 5. The circulating air with a higher temperature and the ambient air with a lower temperature exchange heat with the high-temperature clinker to form high-temperature flue gas. Except for part of the flue gas used in the cement production line, the remaining exhaust gas enters the kiln head thermal oil heat exchanger 2 through the residual air outlet of the grate cooler 1. The exhaust gas is heated by the thermal oil to reduce the temperature, and is discharged from the flue gas outlet of the kiln head thermal oil heat exchanger 2 into the kiln head dust collector 3 for the next round of heat exchange. The clinker in the high-temperature section of the grate cooler 1 needs to be quenched, and the clinker temperature needs to be controlled at the place where the clinker exits the grate cooler 1. Therefore, the ambient air with a lower temperature is blown into these two places for cooling. The clinker cooling in the medium-temperature section and the low-temperature section of the grate cooler 1 has no effect on the clinker performance, and the circulating air with a higher temperature can be used for cooling. Therefore, the recycling of the waste gas of the cement kiln grate cooler 1 improves the waste heat utilization rate of the entire ORC waste heat power generation device, and no excess waste gas is discharged into the atmosphere, and there is no need to set up a chimney. It is a completely closed cycle. Preferably, the inlet of the kiln head thermal oil heat exchanger 2 is connected to the outlet of the grate cooler waste gas 1, and there is no hole in the middle of the grate cooler to connect to the kiln head thermal oil heat exchanger 2 through a pipeline. The inlet 2a and outlet valves 2b of the kiln head thermal oil heat exchanger 2 are used for regulation, and are used to adjust the amount of waste gas entering the kiln head thermal oil heat exchanger.

[0023] At the same time, the kiln head heat transfer oil heat exchanger takes air from the exhaust gas outlet of the grate cooler as the air intake, and no longer takes air from the middle of the grate cooler as the air intake. This setting has the following beneficial effects compared to the middle of the grate cooler:

[0024] (1) After adopting the circulating air of the grate cooler, the outlet temperature of the grate cooler exhaust gas increased by 50-70°C, to about 300-400°C. This temperature level is suitable for ORC waste heat power generation and there is no need to increase the temperature further;

[0025] (2) Avoid taking air from the middle of the grate cooler and ensure that the air intake duct is unobstructed, which can reduce flow resistance and power consumption of the head exhaust fan;

[0026] (3) The size of the air intake, the diameter of the air intake pipe and the angle of the air intake pipe arrangement are no longer subject to too many constraints. By increasing the air intake, the diameter of the air intake pipe and the inclination angle of the pipe, the amount of clinker particles carried by the exhaust gas can be reduced, thereby reducing the wear of the heat exchange pipe of the kiln head heat transfer oil heat exchanger, and the wear and leakage rate of the kiln head heat transfer oil heat exchanger is greatly reduced;

[0027] (4) All the waste gas from the grate cooler enters the kiln head thermal oil heat exchanger, and there is no problem of air leakage from the bypass pipeline valve, thus achieving 100% utilization of waste heat resources;

[0028] (5) The kiln head thermal oil heat exchanger is not only a heat exchange device, but also a cooling device for the cement kiln. It realizes the series connection between the kiln head thermal oil heat exchanger and the cement production line, eliminating the cooling equipment and bypass pipeline.

[0029] (6) It is more conducive to the safe and stable operation of the kiln head heat transfer oil heat exchanger. Since the heat transfer oil is a flammable liquid, the natural temperature is about 370-380℃. The air intake temperature in the middle is too high. After the circulating air is used, the temperature can reach 400-450℃, which poses a greater safety hazard. The organic Rankine cycle (ORC) low-temperature waste heat power generation kiln head waste gas circulation device of the cement clinker production line of the utility model is that the cooling fan replaces the cold air in the traditional design with the circulating air part, blows it to the grate cooler, and after heat exchange with the cement clinker, enters the kiln head heat transfer oil heat exchanger through the waste gas outlet of the grate cooler 1, and heats the oil in the kiln head heat transfer oil heat exchanger 2 for ORC waste heat power generation. After the heat exchange, the low-temperature flue gas of about 100-130℃ is dusted by the kiln head dust collector 3, and is led back to the cooling fan in the middle section of the grate cooler 1 by the head exhaust fan 4, thereby completing the closed cycle. The closed cycle device does not have a chimney, that is, there is no waste gas discharge to the outside. Moreover, the kiln head heat transfer oil heat exchanger 2 no longer uses the middle air intake, but uses the grate cooler exhaust gas outlet as the air intake.

[0030] like Figure 1As shown, the kiln tail exhaust gas recovery unit 201 is composed of a kiln tail preheater 7, a kiln tail thermal oil heat exchanger 8, a high-temperature fan 9, a kiln tail dust collector 10, an induced draft fan 11, and a kiln tail chimney 12; wherein: the input end of the kiln tail thermal oil heat exchanger 8 is connected to the kiln tail preheater 7 through a third valve 8a; the output end of the kiln tail thermal oil heat exchanger 8 is connected to the high-temperature fan 9 through a fourth valve 8b; the output end of the high-temperature fan 9 is connected to the kiln tail chimney 12 through the kiln tail dust collector 10 and the induced draft fan 11 in turn; a bypass pipeline 13 is connected in parallel between the two ends of the kiln tail thermal oil heat exchanger 8; the bypass pipeline 13 adopts a small diameter pipe with a flow capacity of 50% to 60%, and the bypass pipeline 13 is also provided with a fifth valve 8c. The kiln tail heat transfer oil heat exchanger 8 uses the outlet of the kiln tail preheater 7 directly as the inlet pipe of the heat exchanger, and the kiln tail heat transfer oil heat exchanger 8 is used as the main route, and the small diameter bypass pipe 13 is used as the bypass pipe of the kiln tail heat transfer oil heat exchanger 8 in the accident state. The flue gas entering the kiln tail heat transfer oil heat exchanger 8 is more comfortable and the device resistance is reduced. At the same time, a small diameter bypass pipe 13 with a flow capacity of 50% to 60% is used as a bypass pipe to cut off the kiln tail heat transfer oil heat exchanger 8 in the accident state. The inlet valve 8a of the kiln tail heat transfer oil heat exchanger is connected to the pipe after the outlet valve 8b of the kiln tail heat transfer oil heat exchanger 8 through the small diameter bypass pipe 13. In the fault state of the kiln tail heat transfer oil heat exchanger, the exhaust gas at the outlet of the kiln tail preheater 7 can discharge the flue gas through the bypass pipe 13. At the same time, the bypass valve 8c on the small diameter bypass pipe 13 can be used to adjust the flue gas amount entering the kiln tail heat transfer oil heat exchanger. The inlet valve 8a and outlet valve 8b of the kiln tail heat transfer oil heat exchanger can be used for shutoff. Once the kiln tail heat transfer oil heat exchanger is in a fault state, the inlet valve is shut off to inspect and repair the kiln tail heat transfer oil heat exchanger.

[0031] Compared with the traditional ORC waste heat power generation kiln tail exhaust gas recovery device, the utility model uses the kiln tail thermal oil heat exchanger as the main circuit design, and adopts a small pipeline bypass pipe as the bypass pipeline of the kiln tail thermal oil heat exchanger. This makes the smoke inlet of the kiln tail thermal oil heat exchanger 8 smoother and reduces the flow resistance. At the same time, the diameter of the bypass pipeline 13 of the small pipeline is significantly smaller than that of the traditional kiln tail preheater downcomer, reducing the pipe material consumption and reducing the investment cost.

[0032] The above is only a preferred embodiment of the present invention, but it is not limited to the above specific embodiments. For ordinary technicians in this field, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A waste heat recovery system for low-temperature waste heat power generation in a cement clinker production line (ORC), characterized by: The recovery system includes a kiln head waste gas circulation unit and a kiln tail waste gas recovery unit, wherein: The kiln head exhaust gas circulation unit is composed of a grate cooler (1), a kiln head heat transfer oil heat exchanger (2), a kiln head dust collector (3), a head exhaust fan (4), and a cooling fan (5); wherein: the input end of the kiln head heat transfer oil heat exchanger is connected to the exhaust gas outlet of the grate cooler through a first valve; its output end is connected to the head exhaust fan through a second valve and the kiln head dust collector in sequence; the output end of the head exhaust fan is connected to the grate cooler (1) through a cooling fan; The kiln tail exhaust gas recovery unit is composed of a kiln tail preheater (7), a kiln tail heat transfer oil heat exchanger (8), a high-temperature fan (9), a kiln tail dust collector (10), an induced draft fan (11), and a kiln tail chimney (12); wherein: the input end of the kiln tail heat transfer oil heat exchanger (8) is connected to the kiln tail preheater (7) through a third valve; the output end thereof is connected to the high-temperature fan (9) through a fourth valve; the output end of the high-temperature fan (9) is connected to the kiln tail chimney (12) through the kiln tail dust collector (10) and the induced draft fan (11) in sequence; A bypass pipeline (13) is connected in parallel between the two ends of the kiln tail heat transfer oil heat exchanger (8); the bypass pipeline adopts a small pipe diameter with a flow capacity of 50% to 60%, and a fifth valve is also arranged on it.

2. According to claim 1, a low-temperature waste heat power generation and waste heat recovery system for a cement clinker production line (ORC), characterized in that: The cooling fan (5) delivers the circulating air into the grate cooler (1), and after heat exchange with the cement clinker, the circulating air enters the kiln head thermal oil heat exchanger (2) from its exhaust gas outlet; the kiln head thermal oil heat exchanger (2) heats the thermal oil therein according to the exhaust gas delivered, and generates electricity for the waste heat device; at the same time, the kiln head thermal oil heat exchanger (2) delivers the low-temperature flue gas of 100 to 130° C. after heat exchange to the kiln head dust collector (3); the head exhaust fan (4) receives the flue gas filtered by the kiln head dust collector (3) and leads it back to the cooling fan to complete the closed cycle of the exhaust gas.

Images