A sludge disc drying system and drying process

Abstract

The present invention relates to the technical field of sludge treatment, in particular to a sludge disc drying system and a drying process, comprising a disc dryer, wherein at least two feeding ports and a carrier gas inlet and a carrier gas outlet are arranged at the upper part of the disc dryer, wherein the carrier gas outlet is connected to a cyclone separator, wherein the upper outlet of the cyclone separator is connected to the lower inlet of a condenser, and the lower outlet of the condenser is connected to a wastewater delivery pump and a sewage collection tank in sequence; wherein the upper outlet of the condenser is connected to a demister, wherein the first outlet of the demister is connected to the lower inlet of the condenser; wherein the second outlet of the demister is connected to an exhaust fan and a carrier gas inlet in sequence; wherein the lower outlet of the cyclone separator is connected to a first screw conveyor, wherein the outlet of the first screw conveyor is located above a scraper conveyor; wherein the lower outlet of the disc dryer is connected to the inlet of a post-cooling device, wherein the solid material outlet of the post-cooling device is located above the scraper conveyor, and the scraper conveyor is connected to a bucket elevator, a second screw conveyor and a dry sludge bin in sequence.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and specifically relates to a sludge disc drying system. Background Art

[0002] The sludge disc drying system is currently the most widely used sludge drying form in my country. The system output of the traditional disc dryer is generally 100t / d~110t / d (feeding wet sludge with 80% moisture content, discharging wet sludge with 40% moisture content). Air is used as a carrier gas to carry the water vapor evaporated from the sludge out of the dryer and enter the cyclone dust collector and condenser. The water vapor in the carrier gas condenses into sewage and enters the sewage treatment system. A large amount of non-condensable gas enters the deodorization system or directly enters the boiler for incineration. During the sludge drying process, the volume expands first and then shrinks, making it impossible to fully utilize the heat exchange area and space at the middle and rear ends of the disc dryer, and the pushing volume of the material is uneven. The dried sludge carries a certain amount of waste heat into the dried sludge conveying and storage system; the overall system output is low, the amount of odor generated is large, and it is difficult to handle; the dried sludge carries a certain amount of waste heat for natural heat dissipation, the odor is large, and the heat cannot be recovered; the sludge dryer has the risk of particle explosion.

[0003] The traditional disc drying system enters a horizontal disc drying processor through a screw feeder. The rotor of the disc dryer is a group of hollow discs, which are connected by a hollow shaft. A high-temperature medium (steam, hot oil or hot water) circulates in the disc bushing of the dryer, so that all the disc walls in the reactor are heated evenly and effectively. The dehydrated sludge flows in from one end of the dryer, flows through the gap between the disc and the stator, reaches the other end, and flows out through the discharge valve at the bottom. During the sludge drying process, the volume expands first and then shrinks, making it impossible to fully utilize the heat exchange area and space in the middle and rear ends of the disc dryer, and the pushing volume of the material is uneven. The process adopts single-point feeding. During the heat transfer process, the volume of the sludge continues to decrease, and the area of ​​the middle and rear sections of the disc continues to decrease. The large amount of carrier gas generated by the disc dryer is directly sent to the next-level deodorization system after simple condensation treatment, which makes the disc dryer have a large odor treatment capacity and high investment and operating costs. The sludge discharge temperature after drying is high and the odor is strong, resulting in a poor production environment. Summary of the invention

[0004] The object of the present invention is to provide a sludge disc drying system and a drying process.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A sludge disc drying system comprises a disc drying machine, wherein at least two feeding ports are arranged on the upper part of the disc drying machine, and a carrier gas inlet and a carrier gas outlet are also arranged on the upper part of the disc drying machine, wherein the carrier gas outlet is connected to a cyclone separator, wherein the upper outlet of the cyclone separator is connected to the lower inlet of a condenser, and the lower outlet of the condenser is connected to a wastewater delivery pump and a sewage collection tank in sequence; wherein the upper outlet of the condenser is connected to a demister, and the first outlet of the demister is connected to the lower inlet of the condenser; and the second outlet of the demister is connected to an exhaust fan and the carrier gas inlet in sequence;

[0007] The lower outlet of the cyclone separator is connected to the first screw conveyor, and the outlet of the first screw conveyor is located above the scraper conveyor;

[0008] The outlet at the bottom of the disc dryer is connected to the inlet of the post-cooling device, the solid material outlet of the post-cooling device is located above the scraper conveyor, the outlet of the scraper conveyor is connected to the inlet of the bucket elevator, and the outlet of the bucket elevator is connected to the second screw conveyor and the dry sludge bin in sequence;

[0009] The gas outlet of the aftercooling device is connected to the upper inlet of the condenser.

[0010] Wherein, the pipeline between the second outlet of the demister and the exhaust fan is connected to the nitrogen bottle.

[0011] Wherein, an oxygen content detector is provided in the pipeline between the exhaust fan and the carrier gas inlet.

[0012] Wherein, the outlet in the middle of the condenser discharges industrial water.

[0013] The disc dryer has a condensation heat exchange system, steam is introduced into the inlet of the condensation heat exchange system, and the outlet of the condensation heat exchange system is connected to the condensation water tank.

[0014] Wherein, wet sludge is added through the feeding port.

[0015] Among them, industrial water is introduced into the cooling water inlet of the post-cooling device.

[0016] The drying process of the sludge disc drying system is as follows: before the initial operation, the carrier gas pipeline of the system is first filled with nitrogen to reduce the oxygen content of the whole system to about 3% to 4%; the sludge feeding system is turned on, the first feeding port is opened to feed the sludge, a certain time is set, and then the second feeding port is opened, and the sludge feeding system is normally and continuously fed; after the gas evaporated from the sludge is condensed, the carrier gas is demisted and then recycled, and the oxygen content detector set in the carrier gas system detects the oxygen content concentration in the carrier gas, and the oxygen content of the system does not exceed 8%. When it exceeds 8%, the system alarms and the nitrogen filling system is turned on until it drops to about 4%, thereby realizing the carrier gas recycling; the dried sludge is indirectly cooled by the water cooling spiral of the post-cooling device.

[0017] Among them, wet sludge is mainly solid waste generated in sewage treatment, and a small part comes from river sludge, oil sludge in the petrochemical industry, etc.

[0018] Carrier gas recirculation: The gas and air mixture produced by sludge drying is discharged and treated before entering the sludge dryer.

[0019] Post-cooling: Indirect cooling of the hot sludge after drying.

[0020] The present invention adopts two-point or multi-point feeding, the heating and pushing process of the sludge will be more uniform, the heat exchange area of ​​the middle and rear sections of the disc will be fully utilized, and the output of the dried sludge will be increased; the disc carrier gas pipeline is filled with nitrogen during initial operation, and the condensed carrier gas is recirculated after demisting during operation, and an oxygen content detector is provided in the carrier gas system to detect the oxygen content concentration in the carrier gas, so as to realize the carrier gas recirculation and greatly reduce the emission of system odor; the dried sludge is indirectly cooled to reduce the emission temperature and odor of the dried sludge, and recover part of the heat energy.

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

[0022] (1) The present invention proposes for the first time a two-point or multi-point feeding of a disc dryer, which makes the advancement curve of the sludge material more uniform, improves the heat exchange space and area utilization at the middle and rear ends of the disc, and improves the single-machine output of the disc dryer;

[0023] (2) For the first time, measures such as carrier gas demisting and nitrogen filling explosion prevention were proposed in the disc drying system, which achieved the recirculation of the carrier gas system of the disc drying system, eliminated more than 90% of odor emissions, and greatly reduced the risk of particle explosion in the disc dryer;

[0024] (3) The temperature of the dried sludge is lowered by the cooling spiral device to recover part of the heat energy and reduce the temperature and odor of the dried sludge.

[0025] (4) The system increases the output of a single disc dryer by more than 10% and reduces the investment and operating costs of the exhaust deodorization system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the disc drying system of the present invention.

[0027] Among them, 1-disc dryer, 101-feeding port, 102-carrier gas inlet, 103-carrier gas outlet, 2-post-cooling device, 3-cyclone separator, 4-first screw conveyor, 5-scraper conveyor, 6-bucket elevator, 7-second screw conveyor, 8-dry sludge bin, 9-condenser, 10-wastewater delivery pump, 11-wastewater collection tank, 12-nitrogen bottle, 13-demister, 14-exhaust fan, 15-condensate tank. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0029] See also Figure 1 , the present invention provides a technical solution:

[0030] A sludge disc drying system comprises a disc drying machine 1, wherein the upper portion of the disc drying machine 1 is provided with three feeding ports 101, and the upper portion of the disc drying machine 1 is also provided with a carrier gas inlet 102 and a carrier gas outlet 103, wherein the carrier gas outlet 103 is connected to a cyclone separator 3, wherein the upper outlet of the cyclone separator 3 is connected to the lower inlet of a condenser 9, wherein the lower outlet of the condenser 9 is connected to a wastewater delivery pump 10 and a wastewater collection tank 11 in sequence; wherein the upper outlet of the condenser 9 is connected to a demister 13, wherein the first outlet of the demister 13 is connected to the lower inlet of the condenser 9; and wherein the second outlet of the demister 13 is connected to an exhaust fan 14 and the carrier gas inlet 102 in sequence;

[0031] The lower outlet of the cyclone separator 3 is connected to the first screw conveyor 4, and the outlet of the first screw conveyor 4 is located above the scraper conveyor 5;

[0032] The outlet at the bottom of the disc dryer 1 is connected to the inlet of the post-cooling device 2. The solid material outlet of the post-cooling device 2 is located above the scraper conveyor 5. The outlet of the scraper conveyor 5 is connected to the inlet of the bucket elevator 6. The outlet of the bucket elevator 6 is connected to the second screw conveyor 7 and the dry sludge bin 8 in sequence.

[0033] The gas outlet of the aftercooler 2 is connected to the upper inlet of the condenser 9 .

[0034] The pipeline between the second outlet of the demister 13 and the exhaust fan 14 is connected to the nitrogen bottle 12. The pipeline between the exhaust fan 14 and the carrier gas inlet 102 is provided with an oxygen content detector.

[0035] The outlet in the middle of the condenser 9 discharges industrial water. The disc dryer 1 has a condensation heat exchange system, the inlet of which is fed with steam, and the outlet of which is connected to the condensation water tank 15. Wet sludge is added through the feed port 101. The cooling water inlet of the post-cooling device 2 is fed with industrial water.

[0036] The drying process using the sludge disc drying system has the following specific steps:

[0037] (1) First, fill the system's carrier gas pipeline with nitrogen to reduce the oxygen content of the entire system to about 3% to 4%, and the carrier gas blower starts internal circulation;

[0038] (2) The disc dryer starts to enter steam, and the system warms up to the set temperature of 145°C;

[0039] (3) The sludge feeding system is started. First, the first feeding port is opened to feed sludge. The time is set for 1-3 hours. Then the second feeding port is opened. The sludge feeding system feeds sludge continuously and proportionally. The weight ratio of the sludge volume at the first feeding port to the sludge volume at the second feeding port is 2:1 to 4:1.

[0040] (4) After the gas evaporated from the sludge is condensed, the carrier gas is demisted and then recycled. The carrier gas system is equipped with an oxygen content detector to detect the oxygen concentration in the carrier gas. The oxygen content of the system does not exceed 8% (if it exceeds 8%, the system alarms and the nitrogen filling system is turned on until it drops to about 4%), thus realizing the recycling of the carrier gas and greatly reducing the emission of tail gas.

[0041] (5) The dried sludge is discharged to the cooling spiral for cooling, which reduces the odor after the dried sludge treatment.

[0042] This system is used in the #9 disc dryer of the Zhangjiagang sludge drying project. According to the operation data, it is compared with the #8 disc dryer without this system as follows:

[0043]

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A drying process based on a sludge disc drying system, characterized in that: The drying process is specifically as follows: before the initial operation, the carrier gas pipeline of the system is first filled with nitrogen to reduce the oxygen content of the entire system to about 3% to 4%; the mud feeding system is turned on, the first feeding port is opened to feed mud, a certain time is set, and then the second feeding port is opened, and the mud feeding system is normally and continuously fed; after the gas evaporated from the sludge is condensed, the carrier gas is demisted and then recycled, and the oxygen content detector set in the carrier gas system detects the oxygen content concentration in the carrier gas. The oxygen content of the system does not exceed 8%. When it exceeds 8%, the system alarms and the nitrogen filling system is turned on until it drops to about 4%, thereby realizing the carrier gas recycling; the dried sludge is indirectly cooled by the water-cooling spiral of the post-cooling device; The sludge disc drying system comprises a disc drying machine (1), wherein at least two feeding ports (101) are provided at the upper portion of the disc drying machine (1), and a carrier gas inlet (102) and a carrier gas outlet (103) are also provided at the upper portion of the disc drying machine (1), wherein the carrier gas outlet (103) is connected to a cyclone separator (3), wherein the upper outlet of the cyclone separator (3) is connected to the lower inlet of a condenser (9), and the lower outlet of the condenser (9) is connected to a wastewater delivery pump (10) and a wastewater collection tank (11) in sequence; the upper outlet of the condenser (9) is connected to a demister (13), and the first outlet of the demister (13) is connected to the lower inlet of the condenser (9); and the second outlet of the demister (13) is connected to an exhaust fan (14) and the carrier gas inlet (102) in sequence; The lower outlet of the cyclone separator (3) is connected to the first screw conveyor (4), and the outlet of the first screw conveyor (4) is located above the scraper conveyor (5); The outlet at the bottom of the disc dryer (1) is connected to the inlet of the post-cooling device (2); the solid material outlet of the post-cooling device (2) is located above the scraper conveyor (5); the outlet of the scraper conveyor (5) is connected to the inlet of the bucket elevator (6); and the outlet of the bucket elevator (6) is connected to the second screw conveyor (7) and the dry sludge bin (8) in sequence; The gas outlet of the aftercooling device (2) is connected to the upper inlet of the condenser (9).

2. The drying process based on the sludge disc drying system according to claim 1 is characterized in that: The pipeline between the second outlet of the demister (13) and the exhaust fan (14) is connected to the nitrogen bottle (12).

3. The drying process based on the sludge disc drying system according to claim 2 is characterized in that: The pipeline between the exhaust fan (14) and the carrier gas inlet (102) is provided with an oxygen content detector.

4. The drying process based on the sludge disc drying system according to claim 3 is characterized in that: The outlet in the middle of the condenser (9) discharges industrial water.

5. The drying process based on the sludge disc drying system according to claim 4 is characterized in that: The disc dryer (1) has a condensation heat exchange system, steam is introduced into the inlet of the condensation heat exchange system, and the outlet of the condensation heat exchange system is connected to the condensation water tank (15).

6. The drying process based on the sludge disc drying system according to claim 5 is characterized in that: Wet sludge is added through the feeding port (101).

7. The drying process based on the sludge disc drying system according to claim 6 is characterized by: Industrial water is introduced into the cooling water inlet of the post-cooling device (2).

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