A sludge drying system and method for co-firing sludge in coal-fired boilers

Abstract

The present invention discloses a sludge drying system for mixed combustion of sludge in a coal-fired boiler, comprising a primary fan, an air preheater, a sludge conveying channel, a coal mill, a furnace, a wet sludge bin and a feeder; the primary fan, the air preheater, the sludge conveying channel, the coal mill and the furnace are connected in sequence; the outlet of the wet sludge bin is connected to the feed port of the sludge conveying channel through the feeder. The present invention also provides a method for drying sludge using the above-mentioned sludge drying system for mixed combustion of sludge in a coal-fired boiler. The present invention does not require the purchase of drying equipment for drying sludge. At the same time, the existing coal-fired boiler resources are used to dry the sludge, so as to maximize the utilization of resources, remove the cold primary air duct, and all the primary air sent in by the primary fan is passed into the air preheater for heating. The heated hot primary air is conveyed to the sludge conveying channel and used to dry the sludge, so as to ensure the primary air temperature after drying the sludge, reduce the exhaust gas temperature, and improve the furnace combustion efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of thermal power generation, and in particular to a sludge drying system and method for co-firing sludge in a coal-fired boiler. Background Art

[0002] Thermal drying of sludge is mainly divided into direct thermal drying and indirect thermal drying according to whether the heat medium contacts the sludge. In direct thermal drying, heat transfer is achieved through direct contact between wet sludge and hot gas, and the heat of the incoming air provides the latent heat required for evaporation of the liquid in the sludge. Direct drying is the most commonly used type of sludge thermal drying, represented by direct drum dryers, flash dryers, fluidized bed dryers, etc. Indirect drying is also called conduction drying, in which heat transfer is achieved by contact between wet sludge and a hot surface. The heating medium is separated from the metal wall, and the evaporated liquid is removed from the heating medium. Representatives include hollow spiral or disc and vertical indirect drying technologies.

[0003] The prior art requires the use of specific equipment and a certain equipment installation area to dry the sludge, so that the dried sludge can be transported to the coal plant, then mixed with coal, and then transported to the boiler for combustion. For example, the patent with application number CN201911185521.8 discloses a coal-fired coupled sludge drying and incineration system and method considering waste heat utilization, including a sludge storage and transportation system, a sludge drying system, a sludge incineration system and a waste heat utilization system; the sludge storage and transportation system includes a wet sludge bin; the sludge drying system includes a sludge dryer; the sludge incineration system includes a dry sludge bin and a coal-fired boiler; the sludge dryer is provided with a dryer sludge inlet, a dryer steam inlet, a dryer tail gas outlet and a dry sludge outlet. Therefore, the prior art requires a high cost to purchase equipment and land for placing equipment, and at the same time, it cannot use the existing resources of the coal-fired boiler to dry the sludge, and cannot maximize resource utilization.

[0004] The current technology of mixed sludge coal-fired boiler is mainly to directly pass part of the cold air generated by the primary fan into the coal mill, and preheat the other part through the air preheater. The air preheater then passes the hot air into the coal mill. The hot air and cold air in the coal mill are mixed to adjust the temperature of the primary air. The primary air will then carry coal powder into the furnace for combustion. The method of drying sludge using specific equipment is relatively mature, but the method of drying sludge in mixed sludge coal-fired boilers is rare. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to solve the problem that the prior art requires the use of specific equipment and a certain equipment installation area to dry the sludge, which is costly, occupies a large area, and cannot maximize resource utilization.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a sludge drying system for co-firing sludge in a coal-fired boiler, comprising a primary fan, an air preheater, a sludge conveying channel, a coal mill, a furnace, a wet sludge bin and a feeder; the air outlet of the primary fan is connected to the air inlet of the air preheater; the air outlet of the air preheater is connected to the air inlet of the sludge conveying channel, and the air outlet of the sludge conveying channel is connected to the air inlet of the coal mill; a manhole is provided on the furnace, and the air outlet of the coal mill is connected to the inside of the furnace through the manhole; the outlet of the wet sludge bin is connected to the feed inlet of the sludge conveying channel through the feeder.

[0007] Beneficial effect: The present invention does not need to purchase drying equipment for drying sludge. At the same time, existing coal-fired boiler resources are used to dry sludge, so as to maximize resource utilization. The present invention removes the cold primary air duct in the existing coal-fired boiler process, and adopts a method in which all the primary air sent in by the primary fan is passed into the air preheater for heating. The heated hot primary air is transported to the sludge conveying channel and used to dry the sludge. While ensuring the primary air temperature after drying the sludge, the exhaust gas temperature is reduced, thereby improving the furnace combustion efficiency.

[0008] Preferably, it further comprises a first connecting pipe, one end of which is connected to the air outlet of the primary fan, and the other end of which is connected to the air inlet of the air preheater.

[0009] Preferably, it also includes a second connecting pipe, one end of which is connected to the air outlet end of the air preheater, and the other end of which is connected to the air inlet end of the sludge conveying channel.

[0010] Preferably, it further comprises a third connecting pipe, one end of which is connected to the air outlet end of the sludge conveying channel, and the other end of which is connected to the air inlet end of the coal mill.

[0011] Preferably, it further comprises a fourth connecting pipe, one end of which is connected to the air outlet end of the coal mill, and the other end of which is connected to the interior of the furnace through the manhole.

[0012] Preferably, it further comprises a fifth connecting pipe, one end of which is connected to the discharge port of the wet sludge bin, and the other end of which is connected to the feed port of the feeder.

[0013] Preferably, it further comprises a sixth connecting pipe, one end of which is connected to the discharge port of the feeder, and the other end of which is connected to the feed port of the sludge conveying channel.

[0014] The present invention also discloses a sludge drying method for coal-fired boiler co-firing sludge, comprising the following steps:

[0015] S1. First, remove the cold primary air duct and pass all the primary air sent by the primary fan into the air preheater for heating;

[0016] S2, then start the feeder to transport the wet sludge in the wet sludge bin to the sludge transport channel, and at the same time transport the heated hot primary air to the sludge transport channel, and the hot primary air heats and dries the wet sludge;

[0017] S3. After the hot primary air dries the sludge, it drops to a certain temperature and is passed into the coal mill. Then the primary air carries the coal powder into the furnace for combustion.

[0018] Furthermore, the air volume of the primary air delivered by the primary fan in step S1 is 100-700 t / h.

[0019] Furthermore, in step S3, the temperature of the sludge is reduced to 100-150° C. after the hot air drying.

[0020] Beneficial effect: By controlling the air volume of the primary air, while ensuring the air volume delivered to the furnace, the temperature of the primary air entering the coal mill is controlled at an appropriate temperature, ensuring combustion while improving the combustion efficiency of the furnace.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention does not require the purchase of drying equipment for drying sludge. At the same time, existing coal-fired boiler resources are used to dry sludge, maximizing resource utilization. The present invention removes the cold primary air duct in the existing coal-fired boiler process, and adopts a method in which all the primary air sent in by the primary fan is passed into the air preheater for heating. The heated hot primary air is transported to the sludge conveying channel and used to dry the sludge. While ensuring the primary air temperature after drying the sludge, the exhaust gas temperature is reduced, thereby improving the furnace combustion efficiency.

[0023] 2. The present invention controls the air volume of the primary air to ensure the air volume delivered to the furnace and controls the temperature of the primary air entering the coal mill to be at an appropriate temperature, thereby ensuring combustion and improving the combustion efficiency of the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic structural diagram of a sludge drying system for co-firing sludge in a coal-fired boiler according to an embodiment of the present invention.

[0025] Description of Figure Numbers:

[0026] 1. Primary fan; 2. Air preheater; 3. Sludge conveying channel; 4. Coal mill; 5. Furnace; 501. Manhole; 6. Wet sludge bin; 7. Feeder; 8. First connecting pipe; 9. Second connecting pipe; 10. Third connecting pipe; 11. Fourth connecting pipe; 12. Fifth connecting pipe; 13. Sixth connecting pipe. DETAILED DESCRIPTION

[0027] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings of the specification.

[0028] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] Embodiment 1

[0030] like Figure 1 As shown, this embodiment discloses a sludge drying system for co-firing sludge in a coal-fired boiler, comprising a primary fan 1, an air preheater 2, a sludge conveying channel 3, a coal mill 4, a furnace 5, a wet sludge bin 6, a feeder 7, a first connecting pipe 8, a second connecting pipe 9, a third connecting pipe 10, a fourth connecting pipe 11, a fifth connecting pipe 12 and a sixth connecting pipe 13.

[0031] like Figure 1 As shown, the furnace 5 of this embodiment is a coal-fired boiler, and a manhole 501 is provided on one side wall of the furnace 5 .

[0032] like Figure 1 As shown, the air outlet end of the primary fan 1 is detachably connected to the input port of the first connecting pipe 8, and specifically, it can be connected by a flange with bolts. The output port of the first connecting pipe 8 is detachably connected to the air inlet end of the air preheater 2, and specifically, it can be connected by a flange with bolts. The primary air delivered by the primary fan 1 is completely passed into the air preheater 2 through the first connecting pipe 8 for heating; the air outlet end of the air preheater 2 is detachably connected to the input port of the second connecting pipe 9, and specifically, it can be connected by a flange with bolts. The output port of the second connecting pipe 9 is detachably connected to the inlet end of the sludge conveying channel 3, and specifically, it can be connected by a flange with bolts. This structure can be used to convey the heated hot primary air to the sludge conveying channel 3 through the second connecting pipe 9.

[0033] like Figure 1As shown, the outlet of the wet sludge bin 6 is connected to the feed port of the sludge conveying channel 3 through the feeder 7. Specifically, the outlet end of the wet sludge bin 6 is detachably connected to the input port of the fifth connecting pipe 12, and can be specifically connected by a flange with bolts. The output port of the fifth connecting pipe 12 is detachably connected to the feed port end of the feeder 7, and can be specifically connected by a flange with bolts. The feeder 7 of this embodiment is a screw machine in the prior art, and the discharge port end of the feeder 7 is detachably connected to the input port end of the sixth connecting pipe 13, and can be specifically connected by a flange with bolts. The output port of the sixth connecting pipe 13 is detachably connected to the feed port end of the sludge conveying channel 3, and can be specifically connected by a flange with bolts. Start the feeder 7, and the wet sludge in the wet sludge bin 6 can be conveyed to the sludge conveying channel 3.

[0034] like Figure 1 As shown, the outlet end of the sludge conveying channel 3 is detachably connected to the input port of the third connecting pipe 10, and can be specifically connected by a flange with bolts. The output port of the third connecting pipe 10 is detachably connected to the air inlet end of the coal mill 4, and can be specifically connected by a flange with bolts. The outlet end of the coal mill 4 is detachably connected to the input port of the fourth connecting pipe 11, and can be specifically connected by a flange with bolts. The output port of the fourth connecting pipe 11 is connected to the interior of the furnace 5 through the manhole 501. The hot primary air dries the sludge and then drops to a certain temperature and passes into the coal mill 4. Then the primary air carries the coal powder into the furnace 5 for combustion.

[0035] The present invention also discloses a method for using the above-mentioned sludge drying system for co-firing sludge in a coal-fired boiler, comprising the following steps:

[0036] S1. First, remove the cold primary air duct of the existing coal-fired boiler, and pass the primary air sent by the primary fan 1 into the air preheater 2 through the first connecting pipe 8 for heating;

[0037] S2, then start the feeder 7, and transport the wet sludge in the wet sludge bin 6 to the sludge transport channel 3 through the fifth connecting pipe 12 and the sixth connecting pipe 13 in sequence, and at the same time transport the heated hot primary air to the sludge transport channel 3 through the second connecting pipe 9, and the hot primary air heats and dries the wet sludge;

[0038] S3, the hot primary air dries the sludge and reduces its temperature to a certain level, and then passes through the third connecting pipe 10 into the coal mill 4, and then the primary air carries the coal powder into the furnace 5 for combustion.

[0039] Compared with the prior art, the present invention has the following advantages: the present invention does not need to purchase drying equipment for drying sludge. At the same time, the existing coal-fired boiler resources are used to dry the sludge, so as to maximize the resource utilization. The present invention removes the cold primary air duct in the existing coal-fired boiler process, and adopts a method in which all the primary air delivered by the primary fan 1 is passed into the air preheater 2 for heating. The heated hot primary air is transported to the sludge conveying channel 3 and used to dry the sludge. While ensuring the primary air temperature after drying the sludge, the exhaust gas temperature is reduced, thereby improving the combustion efficiency of the furnace 5.

[0040] Embodiment 2

[0041] The difference between this embodiment and the first embodiment is that the air volume of the primary air delivered by the primary fan 1 is controlled to be 100-700 t / h, and the temperature of the hot primary air is controlled to drop to 100-150° C. after drying the sludge.

[0042] Beneficial effect: By controlling the air volume of the primary air, while ensuring the air volume delivered to the furnace 5, the temperature of the primary air entering the coal mill 4 is controlled at an appropriate temperature, thereby ensuring combustion and improving the combustion efficiency of the furnace 5.

[0043] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0044] The above embodiments merely represent implementation methods of the invention. The protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A sludge drying system for co-firing sludge in coal-fired boilers, characterized by: It comprises a primary fan, an air preheater, a sludge conveying channel, a coal mill, a furnace, a wet sludge bin and a feeder; the air outlet of the primary fan is connected with the air inlet of the air preheater; the air outlet of the air preheater is connected with the air inlet of the sludge conveying channel, and the air outlet of the sludge conveying channel is connected with the air inlet of the coal mill; a manhole is provided on the furnace, and the air outlet of the coal mill is connected with the interior of the furnace through the manhole; the outlet of the wet sludge bin is connected with the feed inlet of the sludge conveying channel through the feeder; The method applied to the sludge drying system of the coal-fired boiler co-firing sludge comprises the following steps: S1. First, remove the cold primary air duct and pass all the primary air sent by the primary fan into the air preheater for heating; S2, then start the feeder to transport the wet sludge in the wet sludge bin to the sludge transport channel, and at the same time transport the heated hot primary air to the sludge transport channel, and the hot primary air heats and dries the wet sludge; S3. After the hot primary air dries the sludge, it drops to a certain temperature and is passed into the coal mill. Then the primary air carries the coal powder into the furnace for combustion.

2. The sludge drying system for co-firing sludge in coal-fired boilers according to claim 1, characterized in that: It also includes a first connecting pipe, one end of which is connected to the air outlet end of the primary fan, and the other end of the first connecting pipe is connected to the air inlet end of the air preheater.

3. The sludge drying system for coal-fired boiler co-firing sludge according to claim 1, characterized in that: It also includes a second connecting pipe, one end of which is connected to the air outlet end of the air preheater, and the other end of which is connected to the air inlet end of the sludge conveying channel.

4. The sludge drying system for co-firing sludge in coal-fired boilers according to claim 1, characterized in that: It also includes a third connecting pipe, one end of which is connected to the air outlet end of the sludge conveying channel, and the other end of which is connected to the air inlet end of the coal mill.

5. The sludge drying system for coal-fired boiler co-firing sludge according to claim 4, characterized in that: It also includes a fourth connecting pipe, one end of which is connected to the air outlet end of the coal mill, and the other end of which is connected to the interior of the furnace through the manhole.

6. The sludge drying system for coal-fired boiler co-firing sludge according to claim 1, characterized in that: It also includes a fifth connecting pipe, one end of which is connected to the discharge port of the wet sludge bin, and the other end of which is connected to the feed port of the feeder.

7. The sludge drying system for coal-fired boiler co-firing sludge according to claim 6, characterized in that: It also includes a sixth connecting pipe, one end of which is connected to the discharge port of the feeder, and the other end of which is connected to the feed port of the sludge conveying channel.

8. The sludge drying system for coal-fired boiler co-firing sludge according to claim 1, characterized in that: In step S1, the air volume of the primary air delivered by the primary fan is 100-700 t / h.

9. The sludge drying system for coal-fired boiler co-firing sludge according to claim 1, characterized in that: In step S3, the temperature of the sludge is lowered to 100-150° C. after the sludge is dried by air once.

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