A cement kiln head adjustable step waste heat recovery system

Abstract

The present invention relates to the technical field of waste heat recovery and utilization in cement production, and aims to solve the problem that current technology is difficult to meet the requirements of waste heat recovery efficiency and system stability, and provides an adjustable step waste heat recovery system at the head of a cement kiln, which includes a grate cooler, a high-temperature dust collector, a medium-temperature dust collector, an AQC boiler, a dust collector, an induced draft fan and a chimney. The grate cooler is provided with high / medium / low temperature air intakes; the AQC boiler is provided with high / medium temperature air inlets, and a partition is provided in the AQC boiler. The partition divides the flue gas channel into an evaporator flue and a superheater flue on the flue gas inlet side of the AQC boiler. The superheater flue is connected to the medium-temperature air inlet, and the evaporator flue is connected to the high-temperature air inlet; an evaporator is provided in the evaporator flue, and a superheater is provided in the superheater flue; the superheater flue and the evaporator flue merge into a combined flue in the AQC boiler after the partition. The beneficial effect of the present invention is to meet the requirements of the waste heat recovery system for waste heat recovery efficiency and system working stability.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat recovery and utilization in cement production, and in particular to an adjustable step waste heat recovery system at a cement kiln head. Background Art

[0002] The development and application of cement waste heat recovery technology is an important measure for energy conservation and emission reduction in the cement industry. In the existing technology, in order to utilize the waste heat of the flue gas at the head of the cement kiln to recover and generate electricity, the focus is on how to maximize the extraction of waste heat from the hot end of the grate cooler. The design of the thermal system is a very critical link, which is not only related to the recovery efficiency of the waste heat of the cement kiln system, but also related to whether it can adapt to the fluctuation of the working conditions of the cement kiln system and whether it has the technical conditions for long-term stable operation.

[0003] At present, there are two types of commonly used cement waste heat recovery system technologies: single-pressure thermal system and dual-pressure thermal system. For the single-pressure thermal system, its characteristics are: the system structure is simple, but the heat recovery efficiency is low and the power generation capacity is low. For the dual-pressure thermal system, high-temperature flue gas is usually extracted through the high-pressure section superheater, high-pressure section evaporator, high-pressure section economizer, low-pressure section superheater, low-pressure section evaporator, and common economizer. The characteristics of the dual-pressure thermal system are: the system structure is complex, and the heat recovery efficiency is slightly higher than that of the single-pressure system.

[0004] Therefore, the characteristics and shortcomings of the commonly used cement waste heat recovery system are specifically reflected in:

[0005] 1. The kiln head AQC boiler of the thermal system has many heating surfaces, which are arranged in sequence, resulting in an increase in boiler height, increased boiler flue gas resistance, and more complicated boiler pipeline layout;

[0006] 2. The flue gas volume in the high-temperature section of the grate cooler is relatively small, while the flue gas volume in the low-temperature section is relatively large. Conventional designs usually extract high-temperature flue gas from one point of the grate cooler to pass through the heating surface, without separating the high-temperature heat source from the low-temperature heat source, resulting in poor cascade utilization of heat;

[0007] 3. Usually, once the engineering design is completed, the location of the flue gas extraction port and the heating surface of the waste heat boiler have been determined. Affected by the raw materials and fuel of the cement plant, the actual operation is different from the design conditions. It is difficult for the waste heat recovery system to adjust the heat absorption of the waste heat boiler according to the actual operation of the cement plant. The superheater parameters are difficult to control. The actual steam parameters entering the turbine device deviate from the optimal operating parameters of the turbine design. The turbine deviates from the optimal operating conditions, making the efficiency of the entire waste heat recovery system low;

[0008] In summary, the current technology is difficult to meet the requirements of the cement waste heat recovery system for waste heat recovery efficiency and system working stability. Summary of the invention

[0009] The present invention aims to provide a cement kiln head adjustable step waste heat recovery system to solve the problem that the current technology is difficult to meet the requirements of the cement waste heat recovery system on waste heat recovery efficiency and system working stability.

[0010] The embodiment of the present invention is achieved as follows:

[0011] A cement kiln head adjustable step waste heat recovery system, comprising a grate cooler, a high temperature dust collector, a medium temperature dust collector, an AQC boiler, a dust collector, an induced draft fan and a chimney;

[0012] The front section of the grate cooler is provided with a high-temperature air inlet, the middle section is provided with a medium-temperature air inlet, and the rear section is provided with a low-temperature air inlet;

[0013] The high-temperature air intake is connected to the high-temperature dust collector through a pipeline; a high-temperature regulating valve is arranged on the pipeline to control the amount of flue gas entering the high-temperature dust collector;

[0014] The medium-temperature air intake is connected to the medium-temperature dust collector through a pipeline; a first medium-temperature regulating valve and a second medium-temperature regulating valve are arranged in series on the pipeline to control the amount of flue gas entering the medium-temperature dust collector;

[0015] A bypass channel is provided on the pipeline after the high-temperature regulating valve and the intermediate pipeline between the first medium-temperature regulating valve and the second medium-temperature regulating valve, and a first bypass regulating valve is provided on the bypass channel to adjust and control the amount of flue gas entering the high-temperature pipeline and the medium-temperature pipeline;

[0016] The low-temperature air intake is connected to the dust collector inlet through a low-temperature regulating valve, and the dust collector outlet is connected to the chimney through an induced draft fan;

[0017] A second bypass regulating valve is arranged on the intermediate pipeline between the first medium-temperature regulating valve and the second medium-temperature regulating valve and the pipeline in front of the low-temperature regulating valve to regulate and control the amount of flue gas entering the medium-temperature pipeline and the dust collector;

[0018] The AQC boiler is provided with a high-temperature air inlet and a medium-temperature air inlet. A partition is provided in the AQC boiler. The partition divides the flue gas channel into an evaporator flue and a superheater flue at the flue gas inlet side of the AQC boiler. The superheater flue is connected to the high-temperature air inlet, and the evaporator flue is connected to the medium-temperature air inlet. An evaporator is provided in the evaporator flue, and a superheater is provided in the superheater flue. The superheater flue and the evaporator flue merge into a combined flue in the AQC boiler after the partition, and an economizer is provided in the combined flue.

[0019] After the external feed water absorbs heat through the economizer, one route passes through the water regulating valve and then passes through the evaporator and superheater in sequence, and the other route goes to the SP boiler system;

[0020] The flue gas outlet of the AQC boiler is connected to the dust collector inlet through a pipeline, and a flue valve is arranged on the pipeline.

[0021] In one embodiment:

[0022] The AQC boiler adopts a vertical single-pressure system, the flue gas enters the boiler from the lower end of the boiler, and the superheater, the evaporator and the economizer are all one.

[0023] In one embodiment:

[0024] The evaporator flue and superheater flue of the AQC boiler are respectively extended laterally and bent into an upward U-shaped hook shape, so that the high-temperature air inlet and the medium-temperature air inlet are respectively facing upward; and the high-temperature dust collector and the medium-temperature dust collector are sedimentation-type dust removal structures correspondingly arranged on the inner side of the U-shaped hook part.

[0025] In one embodiment:

[0026] AQC boiler adopts a vertical dual-pressure system, and the flue gas enters the boiler from the upper end of the boiler;

[0027] There are two superheaters, two evaporators and two economizers; the superheater includes a high-pressure section superheater and a low-pressure section superheater, which are arranged in sequence along the flue gas direction; the evaporator includes a high-pressure section evaporator and a low-pressure section evaporator, which are arranged in sequence along the flue gas direction; the economizer includes a high-pressure section economizer and a common economizer, which are arranged in sequence along the flue gas direction;

[0028] One part of the feed water passes through the connecting channels of the common economizer, the low-pressure section evaporator and the low-pressure section superheater, and the other part passes through the connecting channels of the common economizer, the high-pressure section economizer, the high-pressure section evaporator and the high-pressure section superheater.

[0029] In one embodiment:

[0030] The high-temperature dust collector and the medium-temperature dust collector are both cyclone dust collectors independently arranged outside the dual-pressure AQC boiler.

[0031] In one embodiment:

[0032] The air volume extracted by the high-temperature air intake accounts for 20-50% of the total air volume extracted, and the air volume extracted by the medium-temperature air intake accounts for 50-80% of the total air volume extracted.

[0033] In one embodiment:

[0034] The air volume adjusted by the first bypass regulating valve accounts for 0-10% of the total extracted air volume, and the air volume adjusted by the second bypass regulating valve accounts for 0-10% of the total extracted air volume.

[0035] In one embodiment:

[0036] The AQC boiler is arranged horizontally.

[0037] Through the above system settings, the cement kiln head adjustable step waste heat recovery system provided by the present invention has the following beneficial effects:

[0038] 1. Improved the thermal system. AQC boilers have many heating surfaces and are arranged in sequence, which increases the boiler height and the boiler flue gas resistance. The flue is divided into superheater flue and evaporator flue, and the superheater and evaporator are arranged in parallel, which reduces the overall height of the boiler and reduces the boiler flue gas resistance.

[0039] 2. Considering the problem that the flue gas volume in the high-temperature section of the grate cooler is relatively small, while the flue gas volume in the low-temperature section is relatively large, two air inlets are set in the AQC boiler, a superheater is set in the superheater flue of the AQC boiler, and an evaporator is set in the evaporator flue. After passing through the superheater flue and the evaporator flue, they are merged into one flue in the boiler. An economizer is set in the flue to separate the high-temperature heat source from the low-temperature heat source. The high-temperature flue gas is used to heat the superheated steam with a relatively high temperature, and the low-temperature flue gas is used to heat the saturated steam-water mixture with a relatively low temperature, thus realizing the cascade utilization of heat;

[0040] 3. When the actual operating conditions are different from the designed operating conditions, the flue gas volume and flue gas temperature can be regulated and controlled by controlling the opening of different regulating valves. The waste heat recovery system adjusts the heat absorption of the waste heat boiler and the superheated steam parameters according to the actual operating conditions of the cement plant, so that the actual steam parameters entering the turbine device are close to the optimal operating parameters of the turbine design, so that the turbine can operate near the optimal operating conditions, and the efficiency of the entire waste heat recovery system can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings mentioned in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 The structural schematic diagram of an implementation mode of the adjustable step waste heat recovery system at the cement kiln head in the embodiment of the present invention (the arrows in the figure indicate the flow direction of the flue gas or water supply);

[0043] Figure 2 It is a structural schematic diagram of another implementation of the adjustable step waste heat recovery system at the cement kiln head in an embodiment of the present invention (the arrows in the figure indicate the flow direction of the flue gas or water supply).

[0044] Icons: grate cooler 1, high-temperature dust collector 2, medium-temperature dust collector 3, AQC boiler 4, dust collector 5, induced draft fan 6, chimney 7, high-temperature regulating valve 8, first medium-temperature regulating valve 9, second medium-temperature regulating valve 10, low-temperature regulating valve 11, first bypass regulating valve 12, second bypass regulating valve 13, flue valve 14, high-temperature air intake 15, medium-temperature air intake 16, low-temperature air intake 17, bypass channel 18, partition 19, high-temperature air inlet 20, medium-temperature air inlet 21, water regulating valve 22, superheater flue 23, evaporator flue 24, combined flue 25, low-pressure section superheater 26, low-pressure section evaporator 27, high-pressure section superheater 28, high-pressure section evaporator 29, high-pressure section economizer 30, public economizer 31, superheater 32, evaporator 33, economizer 34. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0047] Example

[0048] See also Figure 1 The present embodiment proposes an adjustable step waste heat recovery system at the head of a cement kiln, which comprises a grate cooler 1, a high-temperature dust collector 2, a medium-temperature dust collector 3, an AQC boiler 4, a dust collector 5, an induced draft fan 6 and a chimney 7; a high-temperature air intake 15 is provided at the front section of the grate cooler 1, a medium-temperature air intake 16 is provided at the middle section, and a low-temperature air intake 17 is provided at the rear section; the high-temperature air intake 15 is connected to the high-temperature dust collector 22 through a pipeline; a high-temperature regulating valve 8 is provided on the pipeline to control the amount of flue gas entering the high-temperature dust collector 5; the medium-temperature air intake 16 is connected to the medium-temperature dust collector 33 through a pipeline; a first medium-temperature regulating valve 9 and a second medium-temperature regulating valve 10 are provided in series on the pipeline to control the amount of flue gas entering the medium-temperature dust collector 33.

[0049] A bypass channel 18 is arranged on the pipeline after the high-temperature regulating valve 8 and the intermediate pipeline between the first medium-temperature regulating valve 9 and the second medium-temperature regulating valve 10, and a first bypass regulating valve 12 is arranged on the bypass channel 18 to adjust and control the amount of flue gas entering the high-temperature pipeline and the medium-temperature pipeline; the low-temperature air intake 17 is connected to the inlet of the dust collector 5 through the low-temperature regulating valve 11, and the outlet of the dust collector 5 is connected to the chimney 7 through the induced draft fan 6.

[0050] A second bypass regulating valve 13 is provided on the intermediate pipeline between the first medium-temperature regulating valve 9 and the second medium-temperature regulating valve 10 and the pipeline in front of the low-temperature regulating valve 11 to adjust and control the amount of flue gas entering the medium-temperature pipeline and the dust collector 5.

[0051] The AQC boiler 4 is provided with a high-temperature air inlet 20 and a medium-temperature air inlet 21. A partition 19 is provided in the AQC boiler 4. The partition 19 divides the flue gas channel into an evaporator flue 24 and a superheater flue 23 at the flue gas inlet side of the AQC boiler 4. The superheater flue 23 is connected to the high-temperature air inlet 20, and the evaporator flue 24 is connected to the medium-temperature air inlet 21. An evaporator is provided in the evaporator flue 24, and a superheater is provided in the superheater flue 23. The superheater flue 23 and the evaporator flue 24 merge into a combined flue 25 in the AQC boiler 4 after the partition 19, and an economizer is provided in the combined flue 25.

[0052] After the external feed water absorbs heat through the economizer, one path passes through the water regulating valve 22 and then passes through the evaporator and superheater in sequence, and the other path goes to the SP boiler system; the flue gas outlet of the AQC boiler 4 is connected to the inlet of the dust collector 5 through a pipeline, and a flue valve 14 is provided on the pipeline.

[0053] In this embodiment, the AQC boiler 4 adopts a vertical dual-pressure system, and the flue gas enters the AQC boiler 4 from the upper end of the AQC boiler 4; the superheater, the evaporator and the economizer are all two; the superheater includes a high-pressure section superheater 28 and a low-pressure section superheater 26, and the two are arranged in sequence along the flue gas direction; the evaporator includes a high-pressure section evaporator 29 and a low-pressure section evaporator 27, and the two are arranged in sequence along the flue gas direction; the economizer includes a high-pressure section economizer 30 and a common economizer 31, and the two are arranged in sequence along the flue gas direction; part of the feed water passes through the common economizer 31, the low-pressure section evaporator 27 and the low-pressure section superheater 26 communication channel, and the other part passes through the common economizer 31, the high-pressure section economizer 30, the high-pressure section evaporator 29 and the high-pressure section superheater 28 communication channel. Under this setting mode, optionally, the high-temperature dust collector 22 and the medium-temperature dust collector are both cyclone dust collectors independently arranged outside the dual-pressure AQC boiler 4.

[0054] In this embodiment, under the partition of the partition 19, the width of the evaporator flue 24 is smaller than the width of the superheater flue 23, so that the width of the evaporator is smaller than the width of the superheater.

[0055] In this embodiment, optionally, the high temperature air intake 15 extracts 20-50% of the total air intake, and the medium temperature air intake 16 extracts 50-80% of the total air intake. The first bypass regulating valve 12 adjusts the air volume to 0-10% of the total air intake, and the second bypass regulating valve 13 adjusts the air volume to 0-10% of the total air intake.

[0056] See also Figure 2 In another embodiment, the AQC boiler 4 adopts a vertical single-pressure system, and the flue gas enters the AQC boiler 4 from the lower end of the AQC boiler 4. The superheater 32, the evaporator 33 and the economizer 34 are all one. In this configuration, the evaporator flue 24 and the superheater flue 23 of the AQC boiler 4 are respectively extended and bent in a U-shaped hook shape facing upward, so that the high-temperature air inlet 20 and the medium-temperature air inlet 21 are respectively facing upward; and the high-temperature dust collector 22 and the medium-temperature dust collector 33 are sedimentation-type dust removal structures correspondingly arranged on the inner side of the U-shaped hook part.

[0057] Of course, in other implementations, the AQC boiler 4 may be arranged horizontally as required.

[0058] Through the above system settings, the cement kiln head adjustable step waste heat recovery system provided by the present invention has the following beneficial effects:

[0059] 1. Improved the thermal system. AQC boiler 4 has many heating surfaces and is arranged in sequence, which increases the height of AQC boiler 4 and the flue gas resistance of AQC boiler 4. The flue is divided into superheater flue 23 and evaporator flue 24. The superheater and evaporator are arranged in parallel, which reduces the overall height of AQC boiler 4 and reduces the flue gas resistance of AQC boiler 4.

[0060] 2. In view of the problem that the flue gas volume in the high temperature section of the grate cooler 1 is relatively small and the flue gas volume in the low temperature section is relatively large, two air inlets are set in the AQC boiler 4, a superheater is set in the superheater flue 23 of the AQC boiler 4, and an evaporator is set in the evaporator flue 24. After passing through the superheater flue 23 and the evaporator flue 24, they are merged into one flue in the AQC boiler 4. An economizer is set in the flue to separate the high temperature heat source and the low temperature heat source. The high temperature flue gas is used to heat the superheated steam with a relatively high temperature, and the low temperature section flue gas is used to heat the saturated steam-water mixture with a relatively low temperature, thereby realizing the step-by-step utilization of heat;

[0061] 3. When the actual operating conditions are different from the designed operating conditions, the flue gas volume and flue gas temperature can be regulated and controlled by controlling the opening of different regulating valves. The waste heat recovery system adjusts the waste heat AQC boiler 4 heat absorption according to the actual operating conditions of the cement plant, and adjusts the superheated steam parameters to make the actual steam parameters entering the turbine device close to the optimal operating parameters of the turbine design, so that the turbine can operate near the optimal operating conditions, and the efficiency of the entire waste heat recovery system can be guaranteed.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A cement kiln head adjustable step waste heat recovery system, characterized by: Including grate cooler, high temperature dust collector, medium temperature dust collector, AQC boiler, dust collector, induced draft fan and chimney; The front section of the grate cooler is provided with a high-temperature air inlet, the middle section is provided with a medium-temperature air inlet, and the rear section is provided with a low-temperature air inlet; The high-temperature air intake is connected to the high-temperature dust collector through a pipeline; a high-temperature regulating valve is arranged on the pipeline to control the amount of flue gas entering the high-temperature dust collector; The medium-temperature air intake is connected to the medium-temperature dust collector through a pipeline; a first medium-temperature regulating valve and a second medium-temperature regulating valve are arranged in series on the pipeline to control the amount of flue gas entering the medium-temperature dust collector; A bypass channel is provided on the pipeline after the high-temperature regulating valve and the intermediate pipeline between the first medium-temperature regulating valve and the second medium-temperature regulating valve, and a first bypass regulating valve is provided on the bypass channel to adjust and control the amount of flue gas entering the high-temperature pipeline and the medium-temperature pipeline; The low-temperature air intake is connected to the dust collector inlet through a low-temperature regulating valve, and the dust collector outlet is connected to the chimney through an induced draft fan; A second bypass regulating valve is arranged on the intermediate pipeline between the first medium-temperature regulating valve and the second medium-temperature regulating valve and the pipeline in front of the low-temperature regulating valve to regulate and control the amount of flue gas entering the medium-temperature pipeline and the dust collector; The AQC boiler is provided with a high-temperature air inlet and a medium-temperature air inlet. A partition is provided inside the AQC boiler. The partition divides the flue gas channel into an evaporator flue and a superheater flue at the flue gas inlet side of the AQC boiler. The superheater flue is connected to the high-temperature air inlet, and the evaporator flue is connected to the medium-temperature air inlet. An evaporator is arranged in the evaporator flue, and a superheater is arranged in the superheater flue; the superheater flue and the evaporator flue are merged into a combined flue in the AQC boiler after the partition, and an economizer is arranged in the combined flue; After the external feed water absorbs heat through the economizer, one route passes through the water regulating valve and then passes through the evaporator and superheater in sequence, and the other route goes to the SP boiler system; The flue gas outlet of the AQC boiler is connected to the dust collector inlet through a pipeline, and a flue valve is provided on the pipeline; The AQC boiler adopts a vertical single-pressure system, the flue gas enters the boiler from the lower end of the boiler, and the superheater, the evaporator and the economizer are all one; The evaporator flue and superheater flue of the AQC boiler are respectively extended laterally and bent into an upward U-shaped hook shape, so that the high-temperature air inlet and the medium-temperature air inlet are respectively facing upward; and the high-temperature dust collector and the medium-temperature dust collector are sedimentation-type dust removal structures correspondingly arranged on the inner side of the U-shaped hook part.

2. The cement kiln head adjustable step waste heat recovery system according to claim 1 is characterized by: The air volume extracted by the high-temperature air intake accounts for 20-50% of the total air volume extracted, and the air volume extracted by the medium-temperature air intake accounts for 50-80% of the total air volume extracted.

3. The cement kiln head adjustable step waste heat recovery system according to claim 1 is characterized by: The first bypass regulating valve adjusts the air volume to account for 0-10% of the total extracted air volume, and the second bypass regulating valve adjusts the air volume to account for 0-10% of the total extracted air volume.

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