JPS5939597Y2 - Sludge material drying equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sludge material drying device for drying sludge finally discharged in the food industry or human waste treatment.

Traditionally, this type of sludge has been dried using hot air at a temperature of around 100°C, regardless of direct heating or indirect heating.
This caused foul odors and caused secondary pollution such as dust, noise, and secondary combustion.

This invention was developed in view of the above-mentioned problems, and the feed speed of a multi-stage ventilation conveyor installed in a drying room where warm air at low temperatures (20°C to 40°C) is circulated is adjusted from the upper stage to the lower stage. As drying progresses, the distance between the items to be dried on the conveyor is made closer as the drying process progresses, so that the drying time does not take too long even though the drying is performed using low-temperature hot air. Heating is done by using a heat pump to send out dry, low-temperature air.

Next, the configuration of an embodiment of the present invention will be explained with reference to the accompanying drawings.

Reference numeral 1 denotes a sealed heat-proof drying room, and a drying section 3 houses an air permeable conveyor 2 consisting of a multi-stage net conveyor.
and a heat pump type temperature control and humidity control section 4.

On the top conveyor of the drying section 3, there is a hopper 5, a pair of forming rolls 8, 8 with grooves 6 and protrusions I facing each other in the circumferential direction facing below the hopper 5, and respective forming rolls. A molding device 12 consisting of a set of scrapers 10.11 inserted into every other concave strip 6 of the roll 8 is faced.

Further, a large number of air intake blowers 13 are provided below the 2 groups of conveyors, and are configured to suck air that has absorbed moisture from above and send it to the heat pump type temperature and humidity control section 4.

The heat pump type temperature and humidity control unit 4 is provided with a condenser 16 which serves as a warmer of the heat pump device above an evaporator 14 which serves as a dehumidifier constituting the heat pump device, and a condenser 16 which serves as a warmer of the heat pump device is provided above the condenser 15. An air blower 16 is provided to send out the air to the drying section 3.

Further, the lower water reservoir 17 of the evaporator 14 is communicated with a drain groove 19 outside the drying chamber 1 via a drain pipe 18.

Further, a water pipe 20 drawn out from the cooling coil of the condenser 15 is connected to an air-cooled cooling tower 21 outside the drying chamber 1, and a water pipe 23 led out from the cold water reservoir 22 of the cooling tower 21 is connected to the cooling coil via a pump 24 midway. It is set to be returned to .

Next, a suction blower 25 is installed at the sending end of the lowest conveyor 2.
This blower 25 is connected to a cyclone separator 26.
The air return pipe 28 led out from the upper end of the separator 26 is connected to the drying chamber 1 through the storage tank 2T.

Next, a method of drying sludge material using the above-mentioned apparatus will be explained.

80% of the water ultimately discharged in the food industry, human waste processing, etc.
When ~90% of the sludge is supplied from the hopper 5, it is shaped by forming rolls 8, 8, scraped off by scrapers 10, 11, and falls onto the top conveyor 2 in the form of a 4 mm square bar.

At this time, the scraper 10.11 is removed from the groove 6 of the forming roll 8.
Since they are inserted into every other molded product and spaced apart from each other vertically, the molded products that fall at the same time are kept at a distance and do not overlap or come into contact with each other.

The first stage conveyor 2, which is thus supplied with the material to be dried consisting of shaped sludge material, has a high speed to maintain the distance between the materials to be dried and to reduce contact.

The residence time of the dried material on the first stage conveyor 2 is 10 minutes to 2 minutes.
It is 0 minutes.

Next, the material to be dried is sequentially transferred to the lower conveyor 2 in the second, third, and fourth stages, but as it moves downward, the speed of the conveyor 2 is gradually slowed down, and the residence time of the material is increased. lengthen.

For example, the second stage conveyor 2 takes an average of 25 minutes, the third stage conveyor 2 takes an average of 45 minutes, and the fourth stage conveyor 2 takes an average of 100 minutes. The distance between the sheets should be close and the drying time should be long. Especially, on the fourth conveyor 2 at the lowest stage, the drying time is long because it is dried at a water content of 10% to 30% to prevent mold from forming.

The average drying temperature in drying section 3 is 35°C, wet bulb temperature 2
The temperature was 6.7°C and the relative humidity was 55°C.

The materials to be dried on the conveyor 2 at the lowest stage are sent from this delivery end to a cyclone type separator 26 by a blower 25, where the materials to be dried are separated downward and further transported to a storage tank 27 for storage.

The air is returned to the drying chamber 1 via the air return pipe 28.

The air that has absorbed moisture in the drying section 3 is sent to the lower part of the heat pump type temperature control and humidity control section 4 by a large number of intake blowers 13 provided below, where it is dehumidified, heated, and then sent to the upper air blower 16. The air is sucked in, blown out again toward the drying section 3, and circulated within the drying chamber 1 at a temperature of 20°C to 40°C.

The amount of air blown by the intake blower 13 group is set to be twice to four times the amount of air blown by the air blower 16.

This is to eliminate uneven drying due to an increase in the amount of air inside the drying chamber 1.

If the drying speed is too fast, surface hardening will occur and internal moisture diffusion will be impaired.

In the heat pump type temperature control unit 1 humidity control unit 4, the moisture-absorbing air blown into the lower part is cooled by the evaporator 14 to a temperature below the dew point, and the moisture is separated into water droplets and discharged into the drain groove 19.

The cooled air with reduced absolute humidity is sent to the condenser 15.
The air is heated, the relative humidity is lowered, and the air is blown out again toward the drying section 3 by the air blower 16.

When the drying temperature in the drying section 3 rises too much, a thermostat (not shown) that detects this temperature operates the blower and pump 24 of the cooling tower 21 to lower the temperature of the water circulating in the coil of the condenser 15. Condenser 1
5. Decrease the temperature of the air to be heated.

Next, an experimental example of drying sludge material using the apparatus of the above embodiment will be explained.

1) Experimental conditions Drying temperature Wet bulb temperature Relative humidity Shape of sludge substance 2) Experimental results 35°C 26.7°C 55% 4rIrIrL Square rod shape From the above experimental results, the water content of 80% or more was dried at a low temperature of 35°C. It can be seen that a dried product with a low moisture content can be obtained, and the drying time is not particularly long.

According to the present invention, a multi-stage ventilated conveyor is installed in the drying room where warm air of 20°C to 40°C, which is dehumidified by the evaporator of the heat pump and heated by the condenser, is circulated, so that the air is transferred on the conveyor. The sludge material is dried at a low temperature of 20°C to 40°C, and the proteins, fats, etc. contained in the sludge material are not thermally decomposed, so there is no possibility of foul odors, dust, noise, secondary combustion, etc. Furthermore, since the effective resources contained in the sludge material are dried without being decomposed, it becomes possible to reuse it as fertilizer, feed, etc.

In addition, a hopper is placed above the top conveyor of a plurality of ventilation conveyors provided in the drying chamber, and a molding device is installed at the bottom of this hopper. It consists of a pair of forming rolls with grooves and protrusions facing each other, and a scraper inserted into the grooves of each forming roll, so that the sludge material introduced into the hopper and forming equipment is scraped by the pair of rollers. It is formed into a long, thin rod shape, scraped off with a scraper, and dropped onto the conveyor in a clap-like shape, so it is not clumped together and is dried evenly throughout, preventing it from becoming too dry and turning into dust. No undried parts remain.

Furthermore, even though the drying temperature is low-temperature warm air, we installed a multi-stage ventilated conveyor in the drying chamber with a feed speed that gradually slows down from the upper stage to the lower stage. Since the conveyor in the upper stage of the enclosure has a high feeding speed, the intervals between the clapboard-like drying materials that are supplied are sparse and they do not come into close contact with each other, allowing good ventilation and promoting drying. As drying progresses on the lower conveyor, the feed speed slows down, so the distance between the items to be dried that is supplied from the upper conveyor becomes closer, and the slower conveyor speed is compensated for by increasing the loading capacity, resulting in overall dryness. Since the time does not need to be particularly extended, and the drying of the material to be dried is progressing, even if the distance between the two is close, the evaporation of moisture is unlikely to be interfered with.

Temperature and humidity are controlled by a heated air pump that circulates inside the drying room, so dehumidification and heating can be done in balance, and there is no waste of heat. When heating to a low temperature, it can be operated particularly efficiently, so its capacity can be fully utilized.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a drying device showing an example of implementation of the present invention;
FIG. 2 is a front view of the above molding device, and FIG. 3 is a front view of the same molding roller. 1...Drying room, 2...Breathable conveyor, 5...Hoso'<-, 12"...°°・Molding device 114...Evaporation Vessel, 15... Condenser.

Claims (1)

[Scope of utility model registration request] Dehumidified by the heat pump evaporator and heated by the condenser 2
A drying chamber in which hot air of 0°C to 40°C circulates, and ventilation that is provided in multiple stages within this drying room to transport the material to be dried from the upper stage to the lower stage, and the feeding speed gradually decreases from the upper stage to the lower stage. It consists of a conveyor, a hopper housed above the top conveyor, and a molding device installed at the bottom of the hopper. A device for drying sludge material, comprising a pair of forming rolls facing each other and a scraper inserted into the grooves of each forming roll.