JPH02190307A - Drying method of formed object - Google Patents

Abstract

PURPOSE:To prevent the phenomenon such as the occurrence of cracks or overheating by a method in which a formed object is dried by the radiation of microwave, while fluid passes through the through hole of the formed object, and the moisture concentration in the fluid at the exit of the formed object is detected, whereby the output of the microwave is regulated. CONSTITUTION:Microwave is introduced into a body 1 from a microwave generator 7 and is dispersed therein with a stirrer fan 5, and then is radiated on the catalytic substance 10 on an inner turn table 2. The exhaust tube 19 to which a hygrometer 9 is attached, is connected to its upper side, and the air containing moisture is ejected. The hygrometer 9 detects moisture concentration continuously, and its signal is sent to the microwave generator 7, thereby controlling its output. The moisture inside of the catalytic substance on which microwave is radiated is heated and condenses on its surface. In this state, when the air blown-into from a blower 4 passes the through hole of the catalytic substance 10, the water on its surface is blown off, and the drying is carried out smoothly.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to a honeycomb-structured catalyst and a honeycomb-structured adsorbent for dry flue gas denitrification equipment, which are molded from a material mainly composed of inorganic components and then The present invention relates to a method for drying a molded article having a large number of through holes in the gas flow direction.

[Conventional technology]

BACKGROUND ART Conventionally, a method of drying molded articles such as catalysts has generally used a hot air oven. An example of this conventionally employed hot air drying oven will be explained with reference to FIG. The inside of the drying oven 1 is configured such that a sealing material 2 is installed and a catalyst 3 is housed therein. The air heated by the burner 4 is sent into the drying furnace 1 at 77 liters (not shown), dries the catalyst 3, and then is exhausted. It is discharged from tJ5. Moreover, this drying process lasts for a long period of time.

[Problem to be solved by the invention]

Conventionally, when drying a molded product using a hot air drying oven, the temperature pattern and time necessary for drying the molded product are confirmed in advance through testing, and in reality, the temperature pattern and time required for drying the molded product are
A drying operation was being carried out. However, there is no structure to measure and control the moisture concentration in the drying fluid, so when the moisture in the molded product fluctuates from the specified value, if there is a lot of moisture, the drying may be insufficient and the product will not be baked. If there were problems such as cracking during the process, and there was little moisture in the correspondence, the drying process would be more than necessary, which often caused cracks and deformation during the drying stage.

In view of the above-mentioned state of the art, the present invention provides a method for drying a molded article containing an inorganic component as a main component, especially a molded article having a large number of through holes in the gas flow direction, without the problems described in the prior art. This is what we are trying to provide.

[Means to solve the problem]

In the present invention, when drying a molded product having a large number of through holes in the gas flow direction obtained by mixing and kneading materials mainly composed of inorganic components, a fluid is circulated through the through holes of the molded product. A method for drying a molded product, which comprises drying the molded product by irradiating the molded product with microwaves, detecting the moisture concentration in the fluid at the outlet of the molded product, and adjusting the output of the microwave accordingly. It is.

[For production]

That is, in order to properly dry a molded product having a large number of through holes in the gas flow direction, the present invention dries the molded product by irradiating it with microwaves while flowing fluid through the through holes of the molded product during drying. This device detects the moisture concentration in the fluid at the outlet and controls the microwave output accordingly to maintain a constant state in the molded product after drying even if the moisture content varies during molding. . Using microwaves instead of hot air ovens makes it easy to adjust the output, and the microwave output can be quickly controlled depending on the moisture level at the outlet, making it easier to control the moisture in the molded product. It is from. The reason for detecting and controlling the moisture concentration in the fluid is that as a result of detecting the pattern of changes in the moisture concentration at the outlet during the drying process of the dried material, even if the moisture content of the molded product before drying changes, the drying process will continue. This is because the moisture concentration at the outlet rapidly drops when the gap ends, and an appropriate dry state can be obtained without detecting the state (weight change) of the molded product itself.

An example of a microwave dryer suitable for use in the drying method of the present invention will be described below with reference to FIG.

There is a motor 3 inside the main body 1 of the microwave dryer.
A turntable 2 configured to rotate at the same time and allow air to pass through it.
is installed below, and air can be supplied from below using a blower 4. A waveguide 6 is connected above it, and microwaves from a microwave transmitter 7 are introduced into the main body 1, diffused by a star fan 5, and irradiated onto a catalyst 10 on a turntable 2 inside. be done. An exhaust pipe 8 with a hygrometer 9 attached is connected to the upper part.
Air containing moisture is released. The hygrometer 9 continuously detects the moisture concentration and sends this signal to the microwave transmitter 7 to control its output.

In the microwave dryer configured as described above, the moisture inside the catalyst 10 that has been irradiated with microwaves is heated, and the moisture condenses on the surface.

In this state, what about Prowa 4? The air that has flowed into the catalyst 10
When it passes through the through-hole, the moisture on the surface is blown away, allowing for smooth drying.

[Examples and comparative examples]

100 parts by weight of gypsum, Tie, 15 parts by weight, V2O, 1
1 part of WOS and 1 part of WOS were mixed with 45 parts by weight of a molding aid, 45 parts by weight of water was added, and the mixture was kneaded, followed by molding into a 1 nicomb-shaped molded product (outer diameter: 100 W, length: 300 mL). The shape of the honeycomb is as shown in Figure 2, with a pitch of 9cm.
, the wall thickness is 1.5cm.

This molded product was packed into a microwave dryer as shown in FIG. 1 and dried without passing through the air. As a result, although water evaporated from the molded product, the water condensed on the surface of the molded product, and a sufficient dry state could not be obtained. Also, as a result of checking the weight reduction of molded products over time,
As shown in FIG. 3, a weight loss corresponding to the water content at the time of preparation was not obtained. (Comparative Example 1) The same catalyst as above was filled in the same microwave dryer, and dried for about SO minutes while blowing air at 10 m''/Hr into the microwave dryer inlet.As a result, As shown in Figure 4, although a weight reduction corresponding to the moisture content at the time of preparation was achieved, cracks were observed in the molded product due to excessive drying. (Comparative Example 2) Comparative Example 2 Using a similar method, we investigated the change in moisture in the air at the outlet of the dryer over time, and as shown in Figure 5, the moisture that increased immediately after the start of drying began to rapidly decrease after approximately 70 minutes. The output of the microwave was stopped and the condition of the molded product was checked.As a result, the weight reduction rate was equivalent to the moisture content in the specification, and no cracks had occurred in the molded product.(Example ) [Effects of the Invention] According to the present invention, when drying a molded product having a large number of through holes in the gas flow direction, phenomena such as cracking and overheating can be prevented, and an appropriate dry state can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a pair of microwave dryers used in carrying out the method of the present invention, and Fig. 2 is a molded '11!7 having a large number of through holes in the direction of gas flow to be dried by the method of the present invention. (catalyst) - Figure 5 is a chart showing the relationship between time and weight reduction rate of the molded product according to Comparative Example 1, and Figure 4 is the molded product according to Comparative Example 2. FIG. 5 is a graph showing the relationship between drying time and moisture (wt%) in the fluid at the outlet of a molded product according to an embodiment of the present invention; FIG. 6 is a graph showing the relationship between time and weight reduction rate; 1 is a schematic diagram of an example of a conventional molded product dryer.

Claims (1)

[Claims] When drying a molded product having a large number of through holes in the direction of gas flow, which is obtained by mixing and kneading materials mainly composed of inorganic components, micro A method for drying a molded article, which comprises drying the molded article by irradiating a wave, detecting the moisture concentration in a fluid at the outlet of the molded article, and adjusting the output of the microwave accordingly.