JPH031048Y2 - - Google Patents

Description

[Detailed explanation of the idea]

Industrial Application Fields This invention is useful when a primary dehydrated cake that has been pre-dehydrated using a belt press type dehydrator or the like is dehydrated using a separate type high-pressing device with a separate high-pressing mechanism to reduce the moisture content of the cake. , relates to the structure of a belt-like endless fabric used in the high-pressing device. BACKGROUND ART Recently, a belt press type dewatering device has been used as an effective means for dewatering sludge, and technological improvements are being made to dewater difficult-to-dewater sludge to a low water content. As one means of achieving this, there is a dewatering device in which a portion having a high-pressure mechanism is separated and made independent. For example, Japanese Patent Application Laid-open No. 57-99312 discloses a first dehydrating section consisting of a gravity dehydrating section and a low pressure dehydrating section, and a second dehydrating section having a pressurizing means, and has a cloth that is less dry than the cloth in the first dehydrating section. A dehydration device is disclosed in which the cloth in the second dehydration section has a lower air permeability. These proposals are based on the fact that when the same cloth is used for gravity dehydration, low pressure dehydration, and high pressure dehydration, there is a contradiction in the use of cloth, and it is extremely difficult to select a type of cloth that can be applied to these three categories of dehydration. By separating only the high-pressing mechanism and using a cloth different from the cloth used for pre-dehydration, it was possible to reduce the water content. However, in JP-A-57-99312,
Although it is disclosed that the high-pressure dehydration section uses a fabric with lower air permeability (air permeability per 1 ^cm2 ) than the cloth used for the first dehydration, its specific structure is not clear, and the high-pressure There was a demand for a cloth that was ideal for dehydration. Problems that the invention aims to solve A dewatering device with a separate and independent high-pressure mechanism has
As shown in FIG. 2, there is a device that supplies a cake 8 with a moisture content of about 80% that has been subjected to primary dehydration between two upper and lower endless belt-like cloths 1a and 1b, and compresses the cake 8 with a pressure belt 5 at a high pressure. , these devices are usually provided with a cloth cleaning device 6 . These devices use woven cloth used in belt press type dehydrators, etc. that perform primary dehydration, and have a dense structure (usually woven from monofilament yarn) to reduce air permeability. However, if a surface pressure of 10 kg/cm ² is applied using the apparatus shown in Fig. 2, for example, the primary dehydrated cake will deeply dig into the woven fabric structure, resulting in poor peeling, and there will be a large amount of fabric cake residue, making it difficult to clean the fabric. There were problems such as the fabric's function not being restored even after washing. It was also considered that if the cake was made even denser to prevent it from digging into the fabric structure, the water outflow path would be closed and side leaks would occur. On the other hand, when the felt cloth proposed in JP-A-57-103797 is used, the peeling of the cake is better than that of woven cloth, but when the cake is peeled off, the fuzz of the thread follows the cake, and , fluffing occurs. Further, there were also problems such as fluffing occurring when the felt cloth was washed. Means for Solving the Problems The present invention is installed in a separate type high-pressure dewatering device that supplies a pre-dehydrated primary dehydrated cake 8 and performs high-pressure dehydration using two upper and lower belt-like endless cloths 1a and 1b. In the fabric, a web 3 made of synthetic fibers of 2 to 5 denier mixed with at least 50% of hydrophilic synthetic fibers is laminated at 400 to 800 g/m 2 on one or both sides of a base fabric 4 woven in a multi-layered weave, and the web 3 is laminated with a weight of 400 to 800 g/m ² and then woven by needle punching. It is characterized in that it is combined into one body with a base fabric, and the surface 2 of the fiber laminate is heat-fused and smoothed. Hydrophilic synthetic fibers are polyamide fibers, polyester fibers, etc. that have been treated to make them hydrophilic at the fiber stage, and when mixed with other synthetic fibers (generally hydrophobic) at the fiber stage, they must have a blending ratio of at least 50%. is necessary. Further, after forming the felt body, a hydrophilic treatment may be performed. In this case, the entire constituent fibers will be subjected to hydrophilic treatment. The surface of the web is smoothed by gas baking or by using heated pressure rolls, calender rolls, etc., either alone or in combination, to melt and bond the fibers in the surface layer to form a film with fine pores. In addition, as binder fibers, for example, polyolefins made of multiple components with different melting points, polyester composite heat-adhesive fibers, or low softening point fibers similar to cloth are mixed into the thermoplastic synthetic fiber web and subjected to heat-melting and smoothing treatment. You can. The belt-like cloth of the present invention is produced in an end-shaped form, a suitable joint is made, and then put into a dehydrator to make it into an endless form. FIG. 1 shows a sectional view in the running direction of the cloth according to the present invention, and the high-pressure process of the present invention will be explained using the press using the pressure belt of the dehydrator shown in FIG. 2 as a representative example. The cake is pressurized by two pieces of cloth up to the pressure belt area, and the maximum squeezing pressure is applied at the center of roll 7. Both reach the saturation point, water pressure is generated, and water is released from the cake through the felt and out of the system. It flows out. In this case, it is desirable that the flow resistance within the felt structure be as small as possible, and since hydrophilized webs and the like have an affinity for water, water can flow out of the system smoothly. After passing through the roll center, the water pressure in the felt decreases and tends to return to an unsaturated state. The felt then expands and becomes more unsaturated, creating negative pressure, which also occurs within the cake.
This negative pressure difference between the two causes movement of moisture within the system. Moisture movement also occurs due to capillary force. Here, if the negative pressure in the cake is greater than the negative pressure in the felt, and the capillary diameter in the cake is smaller than that in the felt, water will drain from the felt,
Migrate to the felt, cake interface, and even into the cake. Therefore, if the negative pressure in the cake is large compared to the negative pressure in the felt, the moisture migration in the cake will increase, increasing the moisture content. The present invention has a fiber aggregate of 2 to 5 d of web to minimize moisture migration into the cake, and maintains a lamination amount of 400 to 800 g/m ² to reduce the amount of moisture generated in the felt. The negative pressure has been increased. During peeling, the water film on the interface between the cake and felt acts to enable good peeling. In particular, in the present invention, since hydrophilized fibers or a hydrophilized web are used, the web always maintains a water film on its surface, and exhibits particularly good peeling. In addition, by melting and smoothing the fibers on the surface layer, it is possible to prevent fine sludge particles from entering the web, promote good peeling of the cake, and prevent fluffing and shedding. It is possible. Examples Table 1 shows the specification structure of felts of Examples and Comparative Examples. Opposed roll high compression tests were conducted using these. The test method is as follows: 1. Dehydrate the felt cloth soaked in water.

【table】

[Table] Effect of the invention As shown in the test results, a cake with a lower moisture content can be obtained in the example than in the comparative example. The present invention supplies a pre-dehydrated primary dehydrated cake,
As a fabric for separate type high-pressure dehydration equipment that performs high-pressure dehydration using two belt-like endless cloths (upper and lower), it is possible to reduce the moisture content of the cake, and the surface is heat-fused and smoothed to prevent shedding and fluffing. The effect is extremely effective. There is no doubt that reducing the moisture content of the cake can contribute to labor and energy savings in terms of sludge transportation, incineration, etc.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention. FIG. 2 shows an example of a high-pressing device (pressure belt) in which this invented fabric is used. 1...cloth, 2...cloth surface, 3...web,
4... Base fabric, 5... Pressure belt, 6... Washing device, 7... Pressure roll, 8... Primary dehydration cake,
9...Second dehydrated cake.

Claims (1)

[Scope of utility model registration request] In a filter cloth installed in a separate type high-pressure dehydration device that supplies a pre-dehydrated primary dehydrated cake and performs high-pressure dehydration using two belt-like endless filter cloths (upper and lower), one or both sides of the base cloth woven into a multi-layered weave are used. 2-5 containing at least 50% hydrophilic synthetic fiber
Web made of synthetic fibers of denier 400 ~
A belt-shaped endless filter cloth for separate high-pressure compression, characterized in that 800 g/m ² of fiber laminates are laminated, integrally bonded to a base fabric by needle punching, and then the surface of the fiber laminate is heat-fused and smoothed.