Cement clinker production line preheater system

Abstract

The application discloses a cement clinker production line preheater system, which comprises several stages of cyclone cylinders and connecting pipelines and a decomposing furnace, wherein a C1 waste gas pipeline is connected to the flue gas outlet of the C1 cyclone cylinder, and a heat exchanger for preheating raw materials is connected to the outlet of the C1 waste gas pipeline; the raw materials enter the heat exchanger and exchange heat with high-temperature flue gas from the outlet of the C1 cyclone cylinder, the preheated raw materials enter a C2-C1 connecting pipeline through the outlet material pipe of the heat exchanger, and the cooled flue gas enters a kiln tail waste gas pipeline. The raw material heat exchanger is externally arranged after the C1 cyclone cylinder at the top, so that the system can be changed into a six-stage or more-stage preheater on the basis of the existing five-stage preheater without additionally increasing a layer of kiln tail frame, the system has high heat recovery efficiency, and heat consumption is reduced.

Description

Technical Field

[0001] This invention relates to a preheater system, and more particularly to a preheater system for a cement clinker production line. Background Technology

[0002] The preheating and pre-decomposition system is the core of the new dry process cement clinker calcination system, and its performance has a crucial impact on the stable operation, heat consumption, and power consumption of the entire calcination system. Figure 1 This is a schematic diagram of a conventional preheating and predecomposition system currently used both domestically and internationally. Each stage of the preheater's cyclone separator is stacked vertically and positioned before the high-temperature blower at the kiln tail, within the kiln tail frame. The more stages of the preheater, the higher its gas-solid heat exchange efficiency, the lower the temperature of the exhaust gas at the preheater outlet, and the lower the corresponding system heat consumption.

[0003] Currently, most cement production line kiln tails use five-stage suspension preheaters. The multi-stage preheating of raw materials is achieved through heat exchange units composed of cyclones and connecting pipes, employing a co-current heat exchange method. To meet carbon emission reduction requirements and improve energy efficiency, newly designed systems generally use six-stage preheaters, significantly reducing standard coal consumption. Converting from five-stage to six-stage preheaters meets the substantial energy-saving and consumption-reducing needs of existing five-stage preheater systems. If a conventional approach is adopted, adding a heat exchange unit to the top of the existing kiln tail frame would require adding a layer to the civil engineering kiln tail frame, significantly increasing the load. First, a safety inspection and assessment of the existing structure is necessary, followed by reinforcement and modification according to current standards. Since the foundation depth of the existing kiln tail frame cannot be changed through modification, increasing the floor height could easily lead to the civil engineering frame's height-to-width ratio not meeting standard requirements, and the zero-stress zone of the foundation would also be difficult to meet requirements. Typically, kiln tail frames are demolished and rebuilt, with less reinforcement. Therefore, converting a five-stage preheater to a six-stage preheater is difficult, requires high investment, and has a long construction period.

[0004] It is urgent to explore a simple, efficient, safe and reliable method for retrofitting the multi-stage suspension preheater system of existing cement clinker production lines. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a preheater system for a cement clinker production line that improves system heat recovery efficiency and reduces heat consumption without changing the existing preheater frame.

[0006] Technical solution: The preheater system for cement clinker production line of the present invention includes several stages of cyclones and their connecting pipes, and a decomposition furnace. The flue gas outlet of the C1 cyclone is connected to the C1 exhaust gas duct, and the outlet of the C1 exhaust gas duct is connected to a heat exchanger for preheating the raw materials. The raw materials enter the heat exchanger and exchange heat with the high-temperature flue gas at the outlet of the C1 cyclone. The preheated raw materials enter the C2-C1 connecting pipe through the outlet pipe of the heat exchanger, and the cooled flue gas enters the kiln tail exhaust gas duct.

[0007] The heat exchanger is fixed to the kiln tail frame where the C1 cyclone is located by a support member. Since the structure of the heat exchanger is different from that of the cyclone, it only needs to be fixed by a conventional support frame, and there is no need to add a separate kiln tail frame.

[0008] The heat exchanger is a partitioned heat exchanger; the heat exchanger is made of stainless steel and a high-temperature resistant material.

[0009] The heat exchanger is equipped with an airlock valve on its outlet feed pipe to prevent air leakage at the raw material feeding point and to control the residence time of the raw material in the heat exchanger.

[0010] The high-temperature flue gas at the outlet of the C1 cyclone separator undergoes countercurrent heat exchange, cross-flow heat exchange, co-flow heat exchange, or a combination of co-flow and countercurrent heat exchange within the heat exchanger.

[0011] The raw material is preheated to a temperature of 180-240℃.

[0012] The temperature of the cooled flue gas is 220-260℃; this temperature is the temperature of the exhaust gas outlet at the kiln tail.

[0013] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects: (1) By placing an external raw material heat exchanger after the C1 cyclone at the top, it is not necessary to add an extra layer of kiln tail frame, so that the existing five-stage preheater can be transformed into a six-stage or higher preheater. The system has high heat recovery efficiency and reduced heat consumption; (2) The external raw material heat exchanger adopts a partitioned heat exchanger. The high-temperature flue gas at the outlet of the C1 cyclone can be exchanged with the raw material in countercurrent, cocurrent, cross-flow, or a combination of cocurrent and countercurrent heat exchange, with diverse heat exchange forms; (3) The amount of modification work is small, easy to implement, low investment, and short construction period. Attached Figure Description

[0014] Figure 1 A schematic diagram of a five-stage preheater system in the prior art;

[0015] Figure 2 This is a schematic diagram of the preheater system of the present invention;

[0016] Figure 3 This is a schematic diagram of the structure of the present invention, which involves countercurrent heat exchange between raw material and high-temperature flue gas at C1 outlet.

[0017] Figure 4 This is a schematic diagram of the cross-flow heat exchange structure between the raw material and the high-temperature flue gas at the C1 outlet of the present invention.

[0018] Figure 5 This is a schematic diagram of the co-current heat exchange structure between the raw material and the high-temperature flue gas at the C1 outlet of the present invention.

[0019] Figure 6 This is a schematic diagram of the structure of the present invention, which combines co-current and counter-current heat exchange between raw material and high-temperature flue gas at C1 outlet. Detailed Implementation

[0020] The present invention will now be described in further detail.

[0021] like Figure 1 As shown, taking a five-stage preheater as an example, the existing preheater system includes a decomposition furnace, C1 cyclone separator, C2 cyclone separator, C3 cyclone separator, C4 cyclone separator, and C5 cyclone separator. To transform the existing five-stage preheater system into a six-stage preheater, an additional kiln tail frame is added above the location of the top C1 cyclone separator. Cyclone separators with the same structure and connection relationship as the other cyclone separators are installed on this kiln tail frame.

[0022] like Figure 2 As shown, taking the conversion of a five-stage preheater to a six-stage preheater as an example, the preheater system for a cement clinker production line provided by this invention includes a five-stage cyclone separator and its connecting pipes, and a decomposition furnace, as described in the prior art. The connection relationships between the five-stage cyclones, the connection relationship between the five-stage cyclones and the decomposition furnace, and the operating modes of each component are all existing technologies. The flue gas outlet of the C1 cyclone separator is connected to a C1 exhaust gas duct 3. The outlet of the C1 exhaust gas duct 3 of this invention is connected to a heat exchanger 4 for preheating the raw materials. The heat exchanger 4 is fixed to the kiln tail frame where the C1 cyclone separator 2 is located by a support member. Since the structure of the heat exchanger is different from that of the cyclone separator, it only needs to be fixed by a conventional support frame, without the need to add a separate kiln tail frame. The raw material first enters heat exchanger 4 and exchanges heat with the high-temperature flue gas from the outlet of cyclone 2 (C1) entering heat exchanger 4. After preheating, the raw material enters the C2-C1 connecting pipe 1 between cyclone 2 (C1) and cyclone 2 (C2) through the outlet pipe of heat exchanger 4. The gas exiting the heat exchanger enters the kiln tail exhaust duct 6. An airlock valve 5 is installed on the outlet pipe of heat exchanger 4 to prevent air leakage at the raw material feeding point and control the residence time of the raw material in heat exchanger 4.

[0023] In this embodiment, the heat exchanger 4 is made of stainless steel and a high-temperature resistant material; the heat exchanger 4 is a partitioned heat exchanger. For example... Figure 3-6 As shown, the high-temperature flue gas from the outlet of cyclone 2 (C1) and the raw material can undergo counter-current heat exchange, cross-current heat exchange, co-current heat exchange, or a combination of co-current and counter-current heat exchange within heat exchanger 4. For different scenarios, the directions in which the raw material and the high-temperature flue gas from the outlet of cyclone 2 enter the indirect heat exchanger differ: in counter-current heat exchange, their directions are opposite; in cross-current heat exchange, their directions form a certain angle; in co-current heat exchange, their directions are the same; and in a combination of co-current and counter-current heat exchange, their directions can be either the same or opposite.

[0024] The working principle of this invention is as follows:

[0025] Raw materials from the raw material feeding system enter heat exchanger 4 through the feed inlet, where they undergo counter-current heat exchange with the high-temperature flue gas entering heat exchanger 4. The preheated raw materials then pass through the airlock valve 5 into the C2-C1 connecting pipe 1, thus entering the existing cement clinker production line preheater system. The raw material temperature rises from 50℃ to 180-240℃. The gas temperature exiting the heat exchanger is 220-260℃, which is the temperature of the kiln tail exhaust gas outlet.

Claims

1. A preheater system for a cement clinker production line, comprising several stages of cyclones and their connecting pipes, and a decomposition furnace, wherein, The flue gas outlet of the C1 cyclone (2) is connected to the C1 exhaust gas duct (3). The C1 exhaust gas duct (3) outlet is connected to a heat exchanger (4) for preheating the raw material. The raw material enters the heat exchanger (4) and exchanges heat with the high-temperature flue gas at the outlet of the C1 cyclone (2) entering the heat exchanger (4). The preheated raw material enters the C2-C1 connecting pipe (1) through the outlet material pipe of the heat exchanger (4). The cooled flue gas enters the kiln tail exhaust gas duct (6). The heat exchanger (4) is fixed to the kiln tail frame where the C1 cyclone (2) is located by a support member. The heat exchanger (4) is a partition wall heat exchanger.

2. The cement clinker production line preheater system according to claim 1, characterized in that, The outlet pipe of the heat exchanger (4) is equipped with an airlock valve (5) to prevent air leakage at the raw material feeding point and to control the residence time of the raw material in the heat exchanger (4).

3. The cement clinker production line preheater system according to claim 1, characterized in that, The high-temperature flue gas and raw material at the outlet of the C1 cyclone (2) undergo countercurrent heat exchange, cross-flow heat exchange, co-flow heat exchange, or a combination of co-flow and countercurrent heat exchange in the heat exchanger (4).

4. The cement clinker production line preheater system according to claim 1, characterized in that, The heat exchanger (4) is made of stainless steel and high temperature resistant material.

5. The cement clinker production line preheater system according to claim 1, characterized in that, After heat exchange, the temperature of the raw material after preheating is 180-240℃.

6. The cement clinker production line preheater system according to claim 1, characterized in that, The temperature of the cooled flue gas is 220-260℃.

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