JPS60130499A - Method for cleaning belt of belt press type dehydrator - Google Patents

Abstract

PURPOSE:To economize considerably the labor and time required for detaching and attaching of a filter belt by subjecting the filter belt to primary cleaning with fresh water or filtrate kept under high pressure then to secondary cleaning with an aq. acidic or alkaline soln. CONSTITUTION:An acidic cleaning soln. is used for removing the deposits consisting essentially of inorg. components such as lime and iron-content and hydrochloric acid is used for the acidic soln. An acid soln. of sulfuric acid, nitric acid, etc. is used according to the characteristic of the deposits. An aq. alkaline soln. is used for deposits consisting essentially of org. materials. An aq. alkali hydroxide or ammoniac water or the like is used as the alkali soln. Secondary cleaning may be accomplished continuously at all times in some case but usually the secondary cleaning is accomplished intermittently once a day to prevent clogging or when the filtering efficiency decreases on account of clogging. Tertiary cleaning by fresh water or filtrate is accomplished according to the characteristic of the material to be treated.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a belt press type dehydrator used to dewater various sludges generated from water treatment processes such as tap water, sewage, human waste, and various industrial wastewater. The present invention relates to a belt cleaning method.

Conventional technology) Conventionally, the method of dewatering sludge using a belt press type dehydrator is to uniformly mix sludge and a polymer flocculant in a coagulation mixing tank installed at the front stage to coagulate the sludge, and then to coagulate the sludge in a gravity dewatering section. It is fed onto a running endless filtration belt to perform gravity dewatering, and then fed into a pressurized dewatering section where it is fed to an extension of the endless filtration belt and a running upper endless filtration system installed above and facing the belt. In this method, the material is sandwiched between two belts and is dehydrated by compression and shearing force while running between a plurality of pressing rolls. The dewatered sludge is scraped off by a scraper installed on the reversing part of the filtration belt, and the filtration belt from which the sludge has been removed is circulated to the filtration process, but during the process, it is subjected to high pressure (approximately 3 to 5 ν/cJG). Cleaned with fresh water or filtrate spray.

The above-mentioned conventional one-stage cleaning method of spraying high-pressure water such as fresh water or furnace fluid is effective in removing easily peelable solids and easily water-soluble solids; Lime, iron, fixed organic substances, etc., which are deposited and adhered to the belt and are difficult to peel off, become insufficiently washed and remain in the mesh of the filter belt and gradually grow, resulting in rapid clogging. In addition, since organic polymer flocculants are generally used in belt press type dehydrators, the adhesiveness and poor water solubility of the flocculants have a synergistic effect. The filter belt gets clogged much faster than the filter belt. Conventionally, filter belts that have become clogged and have significantly reduced filtration efficiency are removed from the dehydrator, scrubbed with a brush, and then washed with water, but this takes a lot of effort and time, and lime and other substances adhere strongly to the belt, making it difficult to clean completely. As a result, the rate of clogging increases with each cleaning, and the interval between cleanings becomes shorter, which requires more labor and time and shortens the life of the filtration belt more than necessary.

Purpose of the Invention) The present invention has been made in view of the above circumstances.The present invention prevents clogging of the filter belt and eliminates the need for removal and cleaning, or delays the clogging and lengthens the cleaning interval, thereby saving labor. The purpose is to provide a method that can reduce the amount of water used, enable long-term automatic continuous operation of the dehydrator, and extend the life of the filter belt. In a belt press type dehydrator that dehydrates water by running between a plurality of pressing rolls, the filter belt is first washed with high-pressure fresh water or tear fluid, and then a second wash is performed with an acidic or alkaline aqueous solution. A belt cleaning method for a belt press type dehydrator is characterized in that:

Structure and operation of the invention) The present invention will be described below based on drawings showing embodiments thereof.

FIG. 1 is a schematic sectional view of a belt press type dehydrator to which an embodiment of the cleaning method of the present invention is applied.

1 is a flocculation mixing tank installed in the front stage of the dehydrator, in which sludge A and polymer flocculant B are supplied from the bottom, mixed evenly by the agitator installed at the top, and the flocculation of the sludge is measured. It is equipped with a supply port that supplies water to the dehydrator. Reference numeral 2 denotes a gravity dewatering section consisting of a running endless filtration belt 4, which receives the flocculated sludge supplied from the flocculation mixing tank 1 onto the filtration belt 4, and dewaters it by gravity while the belt runs. . Reference numeral 3 denotes a pressurized dewatering section composed of an extension of the filtration belt 4, a running upper endless filtration belt 5 provided above facing the belt 4, and a plurality of press rolls 6, which performs rough dewatering in the gravity dewatering section 2. The sludge is carried along with the filtration belt 4 and sandwiched between the filtration belt 5 and the sludge, and is subjected to compression and shearing force while traveling between the plurality of squeeze rolls 6 and is further dewatered. 4
, 5 is a belt-shaped filtration belt with a constant width woven from synthetic fibers such as nylon or polyester, which is stretched endlessly between a plurality of rolls and runs at a constant speed in the direction of the arrow by a drive device (not shown). 7.7 is a dehydrated cake cl dehydrated in the pressurized dehydrator 3 using a scraper provided at the inverted part of the filter belt 5.
Peeling due to reversal of ip overbelts 4 and 5 and scraper 7
．． 7, it falls into a hopper (not shown) provided at the bottom and is discharged out of the system. 8 is a fruit juice container that receives the filtered filtrate, collects the liquid, and discharges it to the outside of the system.

At step 9.9, the filter belts 4 and 5 from which the dehydrated cake C has been scraped off after the dehydration process are circulated again to the dehydration process, and are sprayed with high-pressure fresh water or a cleaning spray to wash and remove solid matter adhering to the mesh etc. Clean the front or back surfaces of the filter belts 4 and 5 using a lacrimal wipe.

The washing water may be mixed into the receiver F liquor in the fruit juice container 8, or a separate receiver may be provided and the system may be separate from the F liquor. 10. Reference numeral 10 denotes a cleaning trough which performs secondary cleaning by immersing the E-transfer belts 4 and 5, which have been spray-cleaned with high-pressure water, into a cleaning solution and is filled with an acidic or alkaline aqueous solution as a cleaning solution. In order to ensure that the filter belts 4.5 are immersed in the cleaning liquid, the filter belts 4, 5 are passed through a plurality of rolls to the lower cleaning trough 1, respectively.
It is bent into 0.10.

Generally, acidic cleaning solutions are used to remove stuck substances mainly composed of inorganic components such as lime and iron. Dilute hydrochloric acid (1 to 10%) is usually used as the acidic solution, but other acid solutions such as sulfuric acid or nitric acid may also be used depending on the properties of the solidified material. Moreover, an alkaline aqueous solution is used for fixed substances mainly composed of organic substances.

As the alkaline solution, an aqueous alkali hydroxide solution, aqueous ammonia, or the like is used. The above secondary cleaning may be performed continuously at all times, but usually it is performed intermittently to prevent clogging.
This can be done once a day by filling it with a cleaning solution for 10 to 60 minutes, or if the p hyperactivity rate decreases due to clogging, it can be cleaned each time. The secondary cleaning section may use a spray instead of the cleaning trough. In this case, a receiver should be provided to prevent the cleaning liquid from mixing with the furnace liquid. Since the amount of cleaning liquid attached to the filter belts 4 and 5 after the secondary cleaning is small, the belts are circulated as they are to the dehydration step, but depending on the properties of the material to be treated, a tertiary cleaning with fresh water or p-liquid is performed.

The above is an example in which the present invention is applied to a belt press type dehydrator equipped with two filtration belts, but the filtration belts used in the gravity dehydration section and the pressure dehydration section are separated to form three filtration belts. The cleaning method of the present invention is applied to each filter belt in a belt press type dehydrator equipped with the following.

Effects of the invention) Lime is often used to adjust pH and as a coagulant in water treatment of tap water, sewage, and various industrial wastewater, and iron, etc. from the raw solution and corrosion of equipment gets mixed into the sludge. Because of this, the filter belt gets clogged quickly and has to be removed and washed frequently. Particularly in pulp wastewater, etc., the amount of lime mixed in is large, which causes clogging very quickly. The present invention prevents clogging and eliminates the need for removal and cleaning, or delays clogging and lengthens the interval between removal and cleaning, thereby reducing labor and time required for removing and installing the overpass belt.

■Removal and installation can prevent the filter belt from being damaged during brushing or from being unable to recover due to strongly adhered substances, thereby extending the life of the filter belt.

■Long-term automatic continuous operation is possible because the dehydrator stops frequently.

This method is extremely useful industrially as it has the following effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a belt press type dehydrator to which an embodiment of the cleaning method of the present invention is applied. 1... Coagulation mixing tank, 2... Gravity dehydration section, 6... Pressure dehydration section, 4.5... Filtration belt, 6... Press roll, 7° lay, 10j10... Washing trough 7- A...Sludge, B...Polymer flocculant, C...Dehydrated cake, D...Filtrate. Patent applicant: Mitsubishi Kakoki Co., Ltd. 8- Procedural amendment (method): April 6, 1980 Kazuo Wakasugi, Commissioner of the Patent Office 1, Indication of case: 1982 Patent Application No. 237905 2, Title of invention Belt Belt cleaning method for press-type dehydrator 6. Relationship with the case of the person making the amendment Patent applicant address: 2-6-2 Marunouchi, Chiyoda-ku, Tokyo March 27, 1980 (shipment date) 5. Subject of amendment Full statement

Claims (1)

[Claims] In a belt press type dehydrator that dewaters the workpiece by running it between a plurality of pressing rolls with the workpiece sandwiched between two opposing endless filter belts, the filter belt = first washing with high-pressure fresh water or P liquid. 1. A belt cleaning method for a belt press type dehydrator, which comprises performing a second cleaning using an acidic or alkaline aqueous solution.