TWI642634B - Sludge drying system and method - Google Patents

Abstract

A sludge drying system for drying aqueous sludge, comprising a drum dryer and an air compressor, the drum dryer having a barrel body, a sludge feed port, a sludge discharge port, and a hot air inlet a gas port and a hot air exhaust port, the barrel body surrounds a drying channel, the sludge feed port, the sludge discharge port and the hot air exhaust port are respectively connected to the drying channel, the sludge feed port and the sludge discharge port The water-containing sludge enters and leaves the drying channel respectively, and the hot air inlet and the hot air exhaust port respectively supply a hot air flow into and out of the drying channel to cause the hot air to take away part of the water of the water-containing sludge. The air compressor includes a compressor unit for generating a compressed gas stream and a heat energy recovery unit for heat exchange with the compressor unit to generate the hot gas stream.

Description

Sludge drying system and method

The present invention relates to a sludge treatment technique, and more particularly to a treatment system and method for applying hot air to reduce sludge moisture content.

Sewage treatment is to treat domestic sewage and industrial wastewater to separate solid pollutants in water and reduce the pollution of sewage to the environment. Sewage treatment is often accompanied by the production of a large amount of sludge, which has a high water content and still has a moisture content of 75-85% after being treated by a dehydrator.

In order to reduce the volume of the aqueous sludge and the subsequent sludge cleaning, TW I507366 discloses a sludge treatment device comprising a set of cyclone separation groups 110, and a mixer 120, the injection channel 125 in the mixer 120 Part of the aqueous sludge was dispersed into granules and then further dried in the cyclone separation group 110.

However, the prior art has a drawback in that sludge having a water content of 75-85% tends to adhere to the wall of the mixer 120, which makes the mixer 120 susceptible to unsatisfactory feeding or even clogging. In order to solve the problem caused by the high viscosity of the high water-containing sludge, the conventional solution is to return a part of the dried sludge (low water content) after the cyclone separation group 110 treatment to the mixer 120. Inside, the high water-containing sludge and the low-water sludge are mixed first, and the overall water content is first reduced to less than 75% to reduce the viscosity before the subsequent treatment.

This type of treatment has led to other problems: as part of the dry sludge is sent back to the mixer, this increases the overall amount of sludge to be treated, and the increase in sludge volume leads to more processing time, more energy consumption and More processing costs and reduced system efficiency.

It is an object of the present invention to provide a treatment system that can be used to dry aqueous sludge.

In order to achieve the above and other objects, the present invention provides a sludge drying system for drying aqueous sludge, comprising a drum dryer and an air compressor, the drum dryer comprising a drum having a barrel and a dirt The mud feed port, a sludge discharge port, a hot air inlet port and a hot air exhaust port, the barrel body surrounds a drying passage, and the sludge feed port, the sludge discharge port and the hot air exhaust port are respectively connected In the drying channel, the sludge feed port and the sludge discharge port respectively supply the water-containing sludge into and out of the drying channel, and the hot air inlet and the hot air exhaust port respectively supply a hot air flow into and out of the drying channel to make The hot gas stream carries a portion of the moisture of the aqueous sludge. The air compressor includes a compressor unit for generating a compressed gas stream and a heat energy recovery unit for heat exchange with the compressor unit to generate the hot gas stream.

With the above design, the water-containing sludge can be continuously turned in the drum and exchange heat with the hot gas flow during the turning process, part of the moisture in the water-containing sludge is thus evaporated, and is discharged from the hot air exhaust port along with the hot air flow. The water content of the sludge is thus reduced.

In order to achieve the above and other objects, the sludge drying system may further include a sludge disperser disposed at the feed port and configured to disperse the paste-like water sludge into strips or granular water-containing sludge, thereby increasing water content. The drying efficiency of the sludge in the drum dryer.

In order to achieve the above and other objects, the sludge drying system may further include at least one cyclone disposed downstream of the drum dryer, the cyclone having a cyclone chamber, a sludge inlet, a sludge outlet, a gas inlet, and a The gas outlet, the sludge inlet, the sludge outlet, the gas inlet and the gas outlet are respectively connected to the cyclone chamber, and the sludge inlet and the sludge outlet respectively supply the aqueous sludge into and out of the cyclone chamber, and the gas inlet and the gas outlet respectively A dry gas stream is introduced into and discharged from the cyclone chamber to cause the dry gas stream to carry away a portion of the moisture of the aqueous sludge, thereby further drying the aqueous sludge.

In order to achieve the above and other objects, the sludge drying system may further include a sludge pulverizer disposed downstream of the drum dryer and upstream of the cyclone, and the sludge pulverizer is configured to at least one of the water-containing sludge Partially comminuted into smaller particles, thereby making it easier for the aqueous sludge to rotate with the gas flow in the cyclone and increase drying efficiency.

In order to achieve the above and other objects, the present invention also provides a sludge drying method for drying sludge using the above sludge drying system, which comprises the following steps:

Using a drum dryer to reduce the moisture content of the aqueous sludge to less than 70%;

Using a sludge pulverizer to pulverize a water-containing sludge having a water content of 70% or less into smaller particles;

The granular aqueous sludge is dried by a cyclone to a moisture content of 50% or less.

With the above sludge drying method, the aqueous sludge can be effectively dried, and the aqueous sludge is in the sludge pulverizer and the cyclone without forcibly mixing the low water content sludge (the water content is less than 50%). It is also not easy to stick to the wall, which solves the problem of unsatisfactory feeding or clogging of the conventional technology in the mixer.

In order to achieve the above and other objects, the sludge drying method further comprises: dispersing the paste-like aqueous sludge into strips or granules by using a sludge disperser before introducing the aqueous sludge into the drum dryer. The aqueous sludge, thereby increasing the drying efficiency of the aqueous sludge in the drum dryer.

In this paper, “upstream” and “downstream” are used as the basis for judging the order of treatment of water-containing sludge by each equipment; when one equipment processes water-containing sludge earlier than other equipment, it is said to be “upstream” of other equipment; Conversely, when a device treats water-containing sludge later than other devices, the device is said to be "downstream" of other devices. There may be a conveyor belt, a conveying pipe or the like between the upstream and downstream devices for transporting sludge or gas; in other possible embodiments, two or more devices in the upper and lower directions are in the mechanism. Directly connected or placed in the same enclosure.

By "drying" herein is meant reducing the moisture content of the aqueous sludge, for example, by reducing its moisture content from 80% to less than 50%, rather than being limited to reducing its moisture content to 0%.

Please refer to FIG. 1 , which is a first embodiment of the sludge drying system of the present invention. The sludge drying system 100 includes a feeding mechanism 110 , a sludge disperser 120 , a drum dryer 130 , and an air . The compressor 140, a sludge pulverizer 150, three cyclones 160, 170, 180 and a fan 190. The sludge drying system 100 can be used to dry the aqueous sludge, for example, a sewage treatment plant from domestic wastewater or industrial wastewater, and the sludge produced by the sewage treatment plant can be sent to the sludge drying system 100 before being sent to the sludge drying system 100. The dehydration machine is dehydrated first, and the dehydrator used may be, but not limited to, a filter press, a centrifugal dehydrator or a belt dewatering machine. The water content of the aqueous sludge entering the sludge drying system 100 is, for example, 75-85%. But it is not limited to this.

The feeding mechanism 110 is, for example, a screw for pushing the aqueous sludge in the aqueous sludge tank (not shown) to the sludge disperser 120.

The sludge disperser 120 has a feeding screw 121 and a sieve plate 122. The sieve plate 122 has a plurality of sieve holes 123. The diameter of the sieve holes 123 can be, but not limited to, 2-3 cm. The feeding screw 121 can compare the water content. The high and paste-like aqueous sludge is pushed toward the sieve plate 122, and the aqueous sludge is extruded from the sieve hole 123 to be dispersed into strips or granular water-containing sludge; the paste-like water-containing sludge is dispersed into strips or After the granular aqueous sludge, the overall surface area is increased, so that the drying medium (for example, dry gas) can contact the aqueous sludge in a larger area, and accelerate the drying of the aqueous sludge. In a possible embodiment, a sludge conveyor belt is provided between the sludge disperser and the drum dryer so that the strip or granular sludge can be transported from the sludge disperser to the drum dryer. In other possible embodiments, the sludge disperser is integrated into the drum dryer, and the sludge disperser can directly extrude the strip or granular aqueous sludge in the drum dryer.

The drum dryer 130 includes a drum 131 and a drum motor (not shown) for driving the drum 131 to rotate. The drum 131 has a barrel body 1311, a sludge inlet port 1312, a sludge discharge port 1313, and a The hot air inlet 1314 and the hot air exhaust port 1315, the barrel 1311 enclose a drying passage, and the sludge inlet 1312, the sludge outlet 1313, the hot air inlet 1314 and the hot air outlet 1315 are respectively connected to The drying channel, wherein the sludge feed port 1312 and the sludge discharge port 1313 respectively supply the water-containing sludge into and out of the drying channel, and the hot air inlet 1314 and the hot air exhaust port 1315 respectively supply a hot air flow into and out of the drying channel. The hot gas stream takes away part of the water from the water sludge. In this embodiment, the direction of movement of the hot gas stream and the aqueous sludge in the drying channel is substantially the same. In a possible embodiment, the barrel may have two different openings, one serving as a sludge discharge port and the other as a hot air vent; in other possible embodiments, the barrel has a larger The opening is simultaneously used as a sludge discharge port and a hot air exhaust port, so that the water-containing sludge and the hot air flow exit the barrel through the same opening. The hot gas stream exiting through the hot air exhaust port can be further processed via a gas purifying device 195, for example, using a scrubber to remove dust that may be entrained in the hot gas stream.

The air compressor 140 includes a compressor unit 141 and a heat energy recovery unit 142. The compressor unit 141 can be, for example, a positive displacement compressor or a gas power compressor. The compressor unit 141 can be used to increase the gas pressure to generate a compressed air flow. The recoverer 142 uses gas as a heat exchange medium, and the heat generated by the compressor unit 141 is recovered by heat exchange with the heat recovery unit 142, so that the heat recovery unit 142 can generate the aforementioned hot gas stream, and the heat recovery unit 142 and A gas pipe and another fan may be disposed between the hot air inlets 1314. Both the compressed air stream and the hot gas stream can be used as a drying gas. In a possible embodiment, the hot gas stream may be further heated by other heating units to a desired operating temperature before entering the hot air inlet, such as an electrothermal heater or a fuel heater.

The sludge pulverizer 150 is disposed downstream of the drum dryer 130 and upstream of the cyclone 160. The sludge pulverizer 150 includes a first-stage 151 and a feed passage 152 for guiding the water-containing sludge and the feed passage. The 152 has, for example, the shape of a funnel, the flow passage 151 is for the passage of the compressed air flow, and one of the flow passages 151 is a document throat 153 communicating with the feed passage 152, and the throat portion 153 has a smaller flow passage 151. The cross-sectional area, which causes the flow rate of the compressed gas stream to increase, the pressure to decrease, and the throat portion 153 of the document forms a negative pressure suction force relative to the feed passage 152, so that the water-containing sludge in the feed passage 152 can be guided and sucked into the throat. The portion 153, and then at least a portion of the aqueous sludge is pulverized into smaller particles by the shear force generated by the flow of the high speed machine, so that the particles of the aqueous sludge can be carried out of the flow passage 151 by the compressed air flow.

The cyclones 160, 170, and 180 are sequentially disposed downstream of the drum dryer 130 and the sludge pulverizer 150, and the cyclones 160, 170, and 180 each have a cyclone chamber, a sludge inlet, and a sludge outlet. a gas inlet and a gas outlet, wherein the sludge inlet, the sludge outlet, the gas inlet and the gas outlet are respectively connected to the cyclone chamber, and the sludge inlet and the sludge outlet respectively supply the aqueous sludge into and out of the cyclone chamber, the gas inlet And the gas outlets respectively supply a dry gas stream into and out of the cyclone chamber. The cyclone chamber typically has a circular cross-section, and the gas inlet directs the drying gas stream into the cyclone chamber substantially along the tangential direction of the circular section, causing the dry gas stream to spiral in the cyclone chamber and carry away a portion of the water-containing sludge Moisture. In a possible embodiment, the sludge inlet and the gas inlet may be the same opening on the cyclone, that is, an opening in the cyclone serves as both a sludge inlet and a gas inlet. In a possible embodiment, the sludge outlet and the gas outlet may also be the same opening on the cyclone, that is, an opening in the cyclone serves as both the sludge outlet and the gas outlet. In a possible embodiment, the cyclone has a plurality of gas inlets. In the cyclone 180, sludge and gas exit the cyclone chamber via different openings, and the gas can be directed to the gas purifying device 195 for processing.

The fan 190 is used to increase the gas flow rate, the fan 190 can be used to generate a high-speed airflow, and the high-speed airflow can be combined with the compressed airflow, and the two are combined to be introduced into the gas inlet as the dry airflow; in a possible embodiment, the high-speed airflow does not The high-pressure airflow merges, and the high-speed airflow and the high-pressure airflow are respectively introduced into the cyclone chamber through different openings; in a possible embodiment, a part of the high-speed airflow merges with the high-pressure airflow and is introduced into the cyclone chamber through one of the openings of the cyclone, and the other A portion of the high velocity air stream is introduced into the cyclone via another opening of the cyclone.

By the sludge drying apparatus 100, the aqueous sludge having a water content of 75-85% can be dried by the following sludge drying method: First, the sludge-like water-containing sludge is dispersed into strips by the sludge disperser 120. Or granular water-containing sludge, and then use the drum dryer 130 to reduce the water content of the aqueous sludge to less than 70%, at which time the viscosity of the water-containing sludge is reduced, and it is not easy to adhere to the surface of the processing equipment in subsequent processing; The water-containing sludge having a water content of 70% or less is pulverized into smaller particles by the sludge pulverizer 150, and then the particulate water-containing sludge is further dried to a moisture content of 50% or less by using the cyclones 160, 170, and 180. The required drying treatment.

The advantage of the aforementioned sludge drying method over conventional techniques is that the aqueous sludge can be effectively dried, and the aqueous sludge is in the sludge without forced mixing of the low water content sludge (water content below 50%). The pulverizer and the cyclone are not easy to adhere to the wall surface, which solves the problem that the conventional technique is not suitable for feeding or clogging in the mixer.

Please refer to FIG. 4, which is a second embodiment of the sludge drying system of the present invention. The main difference from the first embodiment is that the hot air flow and the aqueous sludge move in the opposite direction in the drying channel. This contributes to an increase in the drying effect; in addition, the gas discharged from the cyclone 280 is instead processed through another gas purifying device 296 without being introduced into the gas purifying device 295.

In a possible embodiment, the dried sludge may also be refluxed in small amounts as required, but the reflux of the dried sludge is not absolutely necessary in the present invention.

100‧‧‧Sludge drying system

110‧‧‧Feeding agency

120‧‧‧Sludge disperser

121‧‧‧Feed screw

122‧‧‧ sieve plate

123‧‧‧ mesh

130‧‧‧Drum dryer

131‧‧‧Roller

1311‧‧‧Body

1312‧‧‧Sludge feed inlet

1313‧‧‧Sludge outlet

1314‧‧‧hot air inlet

1315‧‧‧hot air exhaust

140‧‧‧Air compressor

141‧‧‧Compressor unit

142‧‧‧heat energy recovery unit

150‧‧‧Sludge pulverizer

151‧‧‧ flow path

152‧‧‧feed channel

153‧‧‧Chinese throat

160, 170, 180‧‧ ‧ cyclones

190‧‧‧Fan

195‧‧‧ gas purification device

280‧‧ Cyclone

295, 296‧‧‧ gas purification device

Fig. 1 is a schematic view showing the configuration of a first embodiment of a sludge drying system of the present invention.

Fig. 2 is a half cross-sectional perspective view showing the sludge disperser of the first embodiment of the sludge drying system of the present invention.

Fig. 3 is a cross-sectional view showing the sludge pulverizer of the first embodiment of the sludge drying system of the present invention.

Fig. 4 is a schematic view showing the configuration of a second embodiment of the sludge drying system of the present invention.

Claims (10)

A sludge drying system for drying aqueous sludge, comprising: a drum dryer comprising a drum having a barrel, a sludge feed port, a sludge discharge port, and a hot air intake a hot air exhaust port, the cylinder body defines a drying passage, the sludge feed port, the sludge discharge port, the hot air inlet port and the hot air exhaust port respectively communicate with the drying channel, and the sludge enters The feed port and the sludge discharge port respectively supply the water-containing sludge into and out of the drying channel, and the hot air inlet port and the hot air exhaust port respectively supply a hot air flow into and out of the drying channel to make the hot gas Flowing away a portion of the moisture of the aqueous sludge; and an air compressor comprising a compressor unit and a thermal energy recovery unit, the compressor unit for generating a compressed gas stream, the heat recovery unit for heating the compressor unit The hot gas stream is produced by exchange. The sludge drying system according to claim 1, further comprising a sludge disperser for dispersing the paste-like aqueous sludge sent to the sludge feed port into strips or granular water-containing sludge. The sludge drying system of claim 2, wherein the sludge disperser has a sieve plate having a plurality of sieve openings. The sludge drying system of claim 3, wherein the sludge disperser has a feed screw for pushing the paste-like aqueous sludge to the sieve plate. The sludge drying system of claim 3, wherein the mesh openings have a pore size of 2-3 cm. The sludge drying system of claim 1, further comprising at least one cyclone disposed downstream of the drum dryer, the cyclone having a cyclone chamber, a sludge inlet, a sludge outlet, a gas inlet, and a a gas outlet, the sludge inlet, the sludge outlet, the gas inlet and the gas outlet are respectively connected to the cyclone chamber, and the sludge inlet and the sludge outlet respectively supply the aqueous sludge into and out of the cyclone chamber, The gas inlet and the gas outlet respectively supply a dry gas stream into and out of the cyclone chamber to cause the dry gas stream to carry away a portion of the moisture of the water-containing sludge. The sludge drying system according to claim 6, further comprising a sludge pulverizer disposed downstream of the drum dryer and upstream of the cyclone, the sludge pulverizer for using at least the water-containing sludge A portion is pulverized into smaller particles. The sludge drying system of claim 7, wherein the sludge pulverizer comprises a Venturi throat for at least a portion of the compressed gas stream and a communicating with the Venturi throat for introducing watery soil The feed channel for the mud. A sludge drying method for drying a water-containing sludge using the sludge drying system according to claim 7 or 8, the sludge drying method comprising the following steps: using the drum dryer to reduce the water content of the water-containing sludge Up to 70% or less; the aqueous sludge having a water content of 70% or less is pulverized into smaller particles by the sludge pulverizer; and the granular aqueous sludge is dried to a moisture content of 50% or less by the cyclone. The sludge drying method according to claim 9, further comprising: dispersing the paste-like water-containing sludge into strips or granules by using a sludge disperser before introducing the water-containing sludge into the drum dryer; Aqueous sludge.