ES2975438A1 - Procedure for drying clay slips for manufacturing ceramic products and installation to carry out said procedure (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Clay slip drying procedure for manufacturing ceramic products and installation to carry out said procedure. The procedure includes a process of atomization and drying of the slip, an absorption process (2) of the water existing in the drying air in absorption equipment using a hydrophilic liquid; and a regeneration process (3) of the hydrophilic absorbent liquid used in the absorption equipment: the drying air is recirculated between the atomization process (1) and the absorption process (2); The hydrophilic absorbent liquid is recirculated between the absorption process (2) and the regeneration process (3). The installation includes an atomizer, water absorption equipment using a hydrophilic liquid, equipment for regeneration of the diluted hydrophilic liquid, means for recirculating the drying air between the atomization equipment and the absorption equipment, and means for recirculation of the hydrophilic liquid between the absorption equipment and the regeneration equipment. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

Drying procedure for clay slips for the manufacture of ceramic products and installation to carry out said procedure

Technical sector

The present invention relates to a process for drying clay slips of the type used in the ceramic industry, particularly in the manufacture of ceramic covering tiles, which improves the energy efficiency of the process.

Background and state of the art

The clay treatment process includes stages of washing, grinding, mixing, where appropriate, and subsequent sieving, obtaining a slip with a high quantity of water not suitable for subsequent dry pressing processes, which must be eliminated by a drying process.

Spray drying is carried out by injecting the slip into a stream of hot, dry air, in which the water evaporates and the atomized clay is separated from the air stream.

Drying of slips is carried out in industrial installations that take an air flow from outside which is heated, normally by gas combustion processes and/or by cogeneration, so that the hot air from the final phase of the process is expelled into the atmosphere while still very hot, despite energy recovery procedures, for example by counter-current preheating of the inlet air. This implies that a significant part of the energy supplied for drying the slip is lost, which implies an energy input cost that should be minimised.

Furthermore, the air to be expelled, although it is duly filtered before being emitted to the outside, may contain unwanted particles, which it would be advisable to avoid.

Explanation of the invention

To solve the problems indicated above, and with special emphasis on energy savings which represent a significant part of the production cost of the atomized clays used in the manufacture of ceramic pieces, a drying process is proposed by means of recirculation and elimination of water from the drying air of the slip, which substantially comprises three processes or exchange phases, as follows:

• A first process or phase consists of the atomization and drying of the slip in an atomizer;

• A second process or phase consists of the absorption of water from the drying air in an absorption equipment; and

• A third process or phase consists of the regeneration of an absorbent hydrophilic liquid used in the absorption equipment.

In the first process, the influents are slip, a mixture of clay and water, and dry air, and the effluents are dry clay and humid air. In other words, in this phase, the humid clay is dried with dry air, with the water or humidity of the clay passing into the air.

The dry air comes from the second process and the dry clay is conducted to a storage tank, from where it will be distributed.

In the second process or phase, the influents are the humid air from the drying of the first process and the concentrated absorbent hydrophilic liquid from the third process. In turn, the effluents of the second process are dry air (the humid air from which the humidity has been extracted), which is returned to the first process, and a hydrophilic liquid, which absorbs water, which is sent to the third process. In this process, the humid air from the drying of the clays is circulated through the hydrophilic liquid, so that the effluent hydrophilic liquid has a high water content, while the air returned to the first process, having transferred water to the hydrophilic liquid, remains dry and can continue drying the slip.

The third process is a regeneration process, which has as tributaries the hydrophilic absorbent liquid diluted with water, and an input of energy. In this process, by adding energy, the water contained in the hydrophilic liquid is evaporated, which is separated into phases of water vapor, which is sent to the outside, and into concentrated hydrophilic liquid, which is returned to the second process, absorption.

Optionally, the process includes filtering of air, hydrophilic liquid and effluent steam, as well as suitable heat exchange processes, in particular of the water vapor obtained by heating, as well as, where appropriate, that from the first and second processes for better use of energy.

This improves the energy efficiency of the plant, improves the ergonomic and health conditions of the plant, and minimises the risk of particle emissions into the atmosphere. In addition, through condensation processes, water can be reused in the grinding of new slips.

It should be noted that the indicated processes are carried out continuously and simultaneously.

The invention also relates to an installation for drying clay slips which includes an atomizer, a water absorption equipment using a hydrophilic liquid, and a regeneration equipment for the diluted hydrophilic liquid by separating the water vapor therefrom, with means for recirculating the drying air between the atomization equipment and the absorption equipment, and means for recirculating the hydrophilic liquid between the absorption equipment and the regenerator respectively.

Brief description of the drawings

To complement the description being made and in order to help better understand the characteristics of the invention, in accordance with a preferred example of its practical implementation, a set of figures is included as an integral part of said description, in which, for illustrative and non-limiting purposes, the following has been represented:

Figure 1 shows a diagram showing the configuration of an installation according to the method of the invention.

The following reference signs can be observed in this diagram:

1 Atomization

2 Absorption process

3 Regeneration

11 Slip entering the atomizer

12 Dry clay removed from the atomizer

21 Humid air from the atomizer

22 Dry air entering the atomizer

31 Hydrophilic absorbent liquid diluted with water

32 Concentrated absorbent hydrophilic liquid

33 steam extracted

34 energy (heat) supplied

Description of the preferred embodiments of the invention

As described above, the present invention relates to a process for drying clays for manufacturing ceramic products that includes the atomization processes (1) of the clays contained in a slip (11), of which approximately 50% by weight is water.

For drying, in the atomization process (1) a mass of dry air (22) is circulated through the pulverized slip (11), the dry air (22) absorbing the water contained in said slip, becoming humid air (21). The humid air (21) is conducted to a second process or absorption process (2) that uses an absorption equipment provided with an absorbent hydrophilic liquid (31,32). At the same time the dry clay (12) is removed and conducted to a storage and supply tank.

Dry air (22) also comes from the absorption equipment and is the moist air (21) from which water has been removed in the absorption process (2). Thus, the air is recirculated between the atomization process, in which the air is charged with moisture, and the absorption process in which the air is dried.

In the absorption process (2) the humid air (21) is passed through the concentrated hydrophilic absorbent liquid (32) which progressively absorbs the water contained in the humid air flow (21), so that the air becomes dry (22) and the absorbent hydrophilic liquid becomes diluted (31); the dry air, as indicated, is redirected to the atomization process (1) and the diluted absorbent hydrophilic liquid (31) is directed to a regeneration process (3).

In the regeneration process (3) water is removed in the form of vapour (33) from the diluted hydrophilic absorbent liquid (31), for which an input of energy (34) is produced, normally in the form of heat. This heat evaporates the water contained in the diluted liquid (31) and returns the concentrated hydrophilic absorbent liquid (32) to the absorption process (2).

As a non-limiting example, it can be stated that the dry air entering the atomisation process will be at a temperature greater than 150°C, the humid air coming from the atomisation process will be at a temperature less than 100°C, the diluted hydrophilic absorbent liquid will have a temperature between 80°C and 140°C, the concentrated hydrophilic absorbent liquid will have a temperature greater than 150°C and the vapour will be expelled or conducted to an exchanger or condenser at a temperature of approx.

350°C.

Other complementary processes and apparatus in the installation can be used within the scope of the present invention. Also, in accordance with the invention, and in order to reuse existing installations as far as possible, the process and installation described can be partially combined with the previous procedures.

Claims (5)

1.- Drying process for clay slips for the manufacture of ceramic products, which comprises an atomization process of a slip containing approximately 50% by weight of clay and 50% by weight of water, characterized by comprising the following processes: • A first process or phase of atomization (1) and drying of the slip in an atomizer; • A second process or phase of absorption (2) of the water existing in the drying air in an absorption equipment; and • A third process or regeneration phase (3) of an absorbent hydrophilic liquid used in the absorption equipment; And because the drying air is recirculated between the atomization process (1) and the absorption process (2); And because the absorbent hydrophilic liquid is recirculated between the absorption process (2) and the regeneration process (3). 2.- Drying process for clay slips for the manufacture of ceramic products, according to claim 1, characterized in that the effluents in the atomization process are: • Slip (11) • Dry air (22) And because the effluents are: • Humid air (21) • Dry clay (12). 3. - Drying process for clay slips for the manufacture of ceramic products, according to any of claims 1 to 2, characterized in that the tributaries in the absorption process are: • Humid air (21) from the atomization process • Concentrated absorbent hydrophilic liquid (32), from the regeneration process And because the effluents are: • Dry air (22), conducted to the atomization process • Diluted hydrophilic absorbent liquid (31). 4. - Drying process for clay slips for the manufacture of ceramic products, according to any of claims 1 to 3, characterized in that the effluents in the regeneration process are: • Energy (34) • Diluted absorbent hydrophilic liquid (31), from absorption And because the effluents are: • Concentrated absorbent hydrophilic liquid (32), which is conducted to the absorption process • Water vapor (33) that is conducted to the outside or to an exchanger or a condenser 5. - Installation for drying clay slips for the manufacture of ceramic products, according to any of claims 1 to 4, characterized by comprising at least the following elements: • An atomizer • A water absorption equipment using a hydrophilic liquid • A regeneration equipment for the diluted hydrophilic liquid Means of recirculating drying air between the atomizing equipment and the absorption equipment Means of recirculating the hydrophilic liquid between the absorption equipment and the regeneration equipment.