JPS5829271B2 - Curing and drying equipment for cement products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for curing and drying cement-based products.

Cement-based boards, such as asbestos-cement boards, are manufactured by curing and then painting uncured boards, but the moisture content after curing is quite high, so it is necessary to dry the curing boards before painting.

Autoclape is sometimes used for the above curing, and in this case, the moisture content of the asbestos cement board after curing is 50 to 16 ml, although it varies depending on the curing time and the temperature of the steam used. When painting, 15 to 12
Needs to be very dry.

Conventionally, curing board materials have been dried by providing a drying process separate from the curing process and drying with hot air, but this method has disadvantages such as extremely high equipment costs and running costs.

The curing and drying device for cement-based products according to the present invention can dry board materials immediately after curing using steam in an autoclave pot, and requires only the addition of a low-floor device to the autoclave pot, reducing equipment costs. This is an extremely advantageous configuration.

That is, the curing and drying apparatus for cement-based products according to the present invention is characterized in that an autoclave pot is provided with a vacuum pulling device and a vacuum releasing device.

First, the principle of drying plate material after curing by the apparatus of the present invention will be explained.

Now, assume that the temperature of the product immediately after curing is T°C, and the moisture content is X.

Furthermore, if the specific heat of this product under anhydrous conditions is a, then the specific heat kx of a product with a moisture content of x% immediately after curing is.

Assume that the inside of the autoclave pot is evacuated immediately after curing, and the inside of the pot is maintained at a vacuum of 100 mmHg, for example.

If this state is maintained for a long time, water evaporates from the product until the product reaches 50° C., as is clear from the water phase diagram shown in FIG.

At around 50°C, the amount of evaporation is small considering the vacuum holding time, so let us assume that the vacuum is held until the product temperature reaches 70°C.

In this case, if the amount of heat required for evaporation is bKcal/ly, then the amount of evaporated water Wxg for 1 kg of product is given by the amount of heat consumed during the temperature of the product from T°C to 70°C (from T, 70)kxKcal/kg. It is given by.

In the above, the initial temperature of the product, that is, the curing temperature T℃
If the temperature is 143°C, the amount of heat required for evaporation at this temperature is 512 Kcal/kg, and on the other hand, the amount of heat required for evaporation at 70°C is 557.5 Kcal/kg, so the above is It can be approximated by these average values, 534, 8
Kcal/kg.

Therefore, assuming that the initial heating temperature of the product is 143° C., the amount of water evaporation Wxg is as follows.

From ■expression and ■expression, becomes.

Therefore, the moisture content X' of the product after vacuuming is
The weight of the raw material per kg is 1000 (1-1 g1) and the initial water content is 1000 □.

. Since it is g, it becomes.

Assuming that the specific heat a of the product under anhydrous conditions is 0.15 and the initial moisture content is 50, the above-mentioned X' becomes a factor of about 39.

After the above vacuum evacuation (product temperature 70°C), the vacuum is released and the temperature in the autoclave pot is 143°C (vapor pressure 4kg).
/i) and reheat the product again to about 143°C,
Vacuum is applied in the same manner as above, and the product temperature is 70°C.
℃, the moisture content at this time is approximately 32%, which is given by substituting the product moisture content X1 after the first evacuation, that is, 39%, into the fourth equation.

As mentioned above, after the product has been cooled to 70°C, the pressure is returned to normal, and the condensed water is discharged from the bottom of the steam curing pot using the drain pump 10', and then 143°C steam is introduced into the pot. In the early stage of the process, the incoming steam is condensed on the surface of the product, and some of this condensed water is absorbed by the product, but the increase in moisture content due to this is at most 1 and can be ignored.

Immediately after curing, the curing and drying apparatus according to the present invention dries the product by repeating the above-mentioned vacuum evacuation, vacuum release, draining of condensed water, and supply of steam, as shown in Figure 2. To,
An example thereof is shown.

In FIG. 2, 1 is an autoclave kettle, to which a steam supply pipe 2 from a boiler is connected.

3 is a vacuum release valve connected to the pot 1.

A is a vacuum system connected to pot 1, valve 4,
It is composed of multi-tubular cooling tanks 5, 5, a condensed water tank 6, a vacuum pump 7, and an exhaust tower 8.

9 is a water tank, 10 is a drainage pump for draining condensed water in the condensed water tank 6 into the water tank 9, and 11 is for circulating the water in the water tank 9 through the cooling inner pipes 51, 51 of the multi-tube cooling tanks 5, 5. 10' is a drain pump for discharging condensed water in the pot, and 12 is a valve.

In FIG. 2, when the curing of the products P, P, . . . is completed, the valve 21 is closed and the supply of steam is interrupted.

Next, when the valve 4 is opened, the vacuum system A is activated, and the inside of the pot 1 is maintained at a predetermined degree of vacuum, for example, 110 Torr, for a predetermined time.

The steam contained in the exhaust gas at the time of evacuation is condensed in the multi-tube cooling pumps 5, 5, and this condensed water tank 6
After that, it is discharged into a water tank 9 by a drainage pump 10.

After evacuation for the predetermined time, the valve 4 of the evacuation system A is closed and the vacuum release valve 3 is opened.

After the vacuum in pot 1 is released, valve 3 is closed.
The valve 21 is opened and steam is introduced into the pot 1 again.

Thereafter, the above series of operations is repeated.

The curing and drying device for cement-based products according to the present invention has the above-described configuration, and by simply adding a vacuum device and a vacuum release device to the autoclave pot for curing high-temperature, high-pressure steam, , Cement products can be dried immediately after curing.

Additionally, curing steam can be used as a heat source.

Therefore, both equipment costs and dry heat source costs can be kept sufficiently low.

Furthermore, it has the advantage of being able to dry the board uniformly, reliably preventing delamination that is inevitable when the surface of the board dries faster than the inside, and even drying even the inside of porous calcium silicate boards. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state diagram of water, and FIG. 2 is an explanatory diagram showing an embodiment of the apparatus of the present invention. In the figure, 1 is an autoclave pot, 3 is a vacuum release valve, and A is a vacuum system.

Claims (1)

[Claims] 1. A curing and drying device for cement-based products, characterized in that an autoclave pot is provided with a vacuum pulling device and a vacuum release device. 2. A curing and drying device for cement-based products, characterized in that an autoclave pot is equipped with a vacuum device, a vacuum release device, and a condensed water drainage device.