CONSTRUCTION BRICK PRODUCTION INDUSTRY IN SOUTHERN THAILAND: A CASE STUDY OF KILN

Purpose: To study the kiln that affect the construction brick production industry and to provide guidelines for solving problems. Method: This is qualitative research collecting data from 17 Kiln brick production industry Owners with in-depth interview. Data is analyzed by content and thematic analysis. Results and Conclusion: (1) Physical characteristics of the furnace square brick kiln model. The structure of this kiln is made of cooked bricks into a rectangular permanent wall. There is a firewood compartment and a brick entry door on the side. Production capacity is 50,000-100,000 bricks/stove. Specific energy was 1.6-3.8 MJ/kg of brick, some stoves use 7.8 MJ/kg brick. (2) Burning temperature. Brick firing in Thailand usually ends at 900 degrees Celsius, with brick heating, brick drying, brick kilning, and temperature reduction. which uses a fairly high temperature for burning. (3) The burning time is approximately 7 days, which corresponds to the temperature of the firing side by heating the bricks, baking the bricks, burning the bricks, and reducing the temperature. By using firewood as a leaven. Therefore, there is a lack of technology development in brick production and efficient brick firing with a long firing period. (4) Heat energy loss. Brick firing in Thailand usually ends at a temperature of 900 degrees Celsius and is then turned off for a few days. To reduce cracking due to sudden temperature changes, then turn on the kiln to let the bricks cool naturally allowing the bricks to cool naturally. The heat energy stored is left and that is a loss of heat energy. Research Implications: Brick burning uses a lot of energy, firewood as fuel, and the efficiency of the kilns used is quite low. It is likely that the efficiency of brick kilns will be improved or brick kilns with high thermal efficiency to be used as a replacement to achieve high efficiency. This allows the brick production industry to continue to exist. Originality/Value: The improvement of fuel using for Kiln in brick burning can be improved for more effectiveness and clean environment.


INTRODUCTION
The kiln is the heart of the ceramic industry as well as the production of construction bricks because the product will be good or bad depending on the kiln because it is the final stage of the product.If damage occurs, it means that the process must be started all over again.
From document study and field visits, it was found that there are two types of brick burning in Thailand: burning with temporary kilns.and burning with a permanent kiln.
Burning bricks in a temporary kiln is approx.30,000-60,000 bricks for burning with rice husks, bricks are usually piled about 1.0-1.5 meters high.This is because they want to be convenient when adding rice husks as fuel.As for the kiln that burns firewood, it can be built as high as 2 meters.The bricks on the lower level are arranged so that they are clear.Some models leave a space for firewood at the bottom.The upper layers are stacked next to each other, but there is space between the blocks to allow the heat to distribute evenly.After the raw bricks are arranged, the walls around the kiln are built using unsized bricks.There will be a distance of about 10-15 cm.from the pile of burned bricks, and the fire spaces will match.The top of this temporary kiln, if it is a rice husk kiln, will be left empty for filling with rice husks when it collapses.If it's a wood-fired stove, bricks are often placed to open the space above.

Rice husk stacking kiln
Source: Phongjesada Mon Brick Factory, 2023 The permanent firing of bricks used in brick factories is a method of cooling up (updraft) and cooling down (downdraft).They come in different shapes, such as round, square, or long kilns.This permanent kiln mostly uses reclaimed wood as fuel.As commonly seen in Thailand, there are 3 types: 1) Dragon Furnace is a furnace that is formed into a tunnel with a slope upwards from the level.The floor leading to the stove is behind and throughout the stove there are compartments to put firewood in at regular intervals.The end of the stove contacts the chimney.When opening the furnace door, the bricks are brought in and arranged so that there are enough gaps until they are tight.Then close the furnace door and start putting fire in the furnace for about 24 hours, then the burning will end.But you must close all the openings to bake the oven for another 72 hours until the oven is sufficiently cool, then open the oven door to take out the cooked bricks.5 2) Taiwanese kiln is a kiln made in the shape of an upside-down pan.The chimney may be in the center or it may extend outside of the burner.There may be several openings for the fire.It is popular to use firewood as fuel.When the bricks are cooked, the mouth of the kiln is sealed, put on the fire and left closed until cool so the bricks were removed from the kiln.
3) Square stove is a kiln that is built in the shape of a square or rectangle.There is a door on one side that opens the kiln for loading bricks in and out.The remaining side is a compartment for putting firewood.
This research has two objectives.The first objective is to study the kilns that affect the construction brick production industry.Second objective is to provide guidelines for solving problems in the construction brick production industry of Thailand.Therefore, if the brick industry, which is a family industry scattered throughout the countryside survives, the need to find the cause of the problem is imperative.The researchers need to study kiln problems affecting the construction brick production industry in southern Thailand is to improve the efficiency of brick kilns or bring brick kilns with high thermal efficiency to be used as a replacement to suit local problem conditions.

BRICK PRODUCTION PROCESS
The construction brick kiln generally consists of 4 steps: baking bricks, preheating bricks, kilning bricks, and reducing brick temperature.A brick kiln uses this entire process.But the energy consumption of each type of stove is different.This depends on the stove being designed.For the use of heat energy There are mainly two types of brick kilns in Thailand: rice husk pile kilns and square brick kilns.

Figure 3
Rectangular brick kiln in the southern Thailand In the southern region of Thailand, a square brick kiln is used.The structure of this kiln is made of cooked bricks into a rectangular permanent wall.Heat flows upwards (updraft).
There is a firewood compartment and a brick entry door on the side.The top of the stove is mostly open.Production capacity is 50,000-100,000 bricks/stove.Arranging raw bricks in the stove will leave a space at the bottom of the stove for putting firewood.From the survey it was found that the specific energy was 1.6-3.8MJ/kg of brick, but some reports found that This type of kiln uses energy as high as 7.8 MJ/kg brick.The cost of the fuel used in kiln accounts for 30-40% of the cost of brick production and is likely to increase.Because at present the price of firewood used is increasing.In the southern region, firewood is used as the main fuel for brick production.

Figure 4
Brick kiln wall Firing bricks in a kiln consists of the 4 processes mentioned above: baking bricks, preheating bricks, kilning bricks and reducing brick temperature.Brick drying involves expelling the water contained in the bricks to evaporate, which uses a temperature in the range of 25-150 degrees Celsius.The time required to dry the bricks depends on the number of bricks and the amount of moisture in the bricks.If baking the bricks is accelerated too quickly, it will cause the bricks to crack when entering the firing process.This is because the moisture cannot completely escape from the soil.Most raw bricks that have gone through the machine-forming process will have about 30% moisture by weight and will be dried until there is about 10-15% moisture remaining before they can be put in the kiln.
The temperature range of 150-400 degrees Celsius is the brick warming period.It removes carbon compounds and volatile substances from bricks.Brick firing starts at a temperature of 400-900 degrees Celsius.During the firing of clay, the structure changes from clay to brick at a temperature of 573 degrees Celsius, with expansion due to the change.
Structure of quartz mineral in clay and at a temperature of 900 degrees Celsius, it will look like glass.Bricks will increase in strength and change color according to the atmospheric conditions in the kiln.
Brick firing in Thailand usually ends at a temperature of 900 degrees Celsius and is then turned off for the first few days at the end of the firing to reduce cracking due to sudden temperature changes, then turn on the kiln to let the bricks cool naturally.Allowing the bricks to cool naturally.The heat energy stored in the cooked bricks will not be put to good use.which is a loss of heat energy.

Composition of clay and effect of heat on clay
The main components in clay are mainly silica, alumina and iron oxide.For iron carbonate, it is small particles.Iron oxide is concentrated in the clay.This causes a dark color to occur in clay bricks that are fired in a reducing atmosphere.The burning of carbon substances.It will start burning from 200-350 ° C, during which time the volatile substances will be released.In order to burn the carbon substances left in the bricks, it will be carbon monoxide.or more carbon dioxide.

RESEARCH METHODOLOGY
Conceptual Framework

POPULATION AND SAMPLE
Population is 17 brick factory owners in Nakhon Si Thammarat Province.

RESEARCH TOOLS
Tools used to collect data in this research is an interview collecting data from owners of Moklan brick kiln factory Nakhon Si Thammarat Province.The interview form is a tool used for data collection.The questions were created from theories, principles, variables, or important issues that require information.

DATA ANALYSIS
The data were analyzed by content analysis and thematic analysis.

RESULTS AND DISCUSSIONS
From an interview with the owner of the Moklan brick kiln factory.Nakhon Si Thammarat Province face-to-face and actually visiting the area to study the whole process found that Issue 1. Characteristics of the furnace square brick kiln model.The structure of this kiln is made of cooked bricks into a rectangular permanent wall.There is a firewood compartment and a brick entry door on the side.The top of the stove is open, usually with a production capacity of 50,000-100,000 bricks/stove.Arranging raw bricks in the stove will leave a line at the bottom of the stove for putting firewood.From the survey it was found that the specific energy was 1.6-3.8MJ/kg of brick, but some reports found that This type of stove uses energy up to 7.8 MJ/kg brick.Issue 3. The burning time, approximately 7 days, is a result of the shape of the furnace and the furnace walls, which are designed according to local wisdom, allowing heat to escape from the furnace walls.As a result, the firing temperature rises slowly and takes a long time.
Including the process of burning bricks in the kiln, it consists of 4 processes: baking bricks, preheating bricks, burning bricks and reducing brick temperature.Issue 4. Heat energy loss Brick firing in Thailand usually ends at a temperature of 900 degrees Celsius and is then turned off for the first few days at the end of the firing.To reduce cracking due to sudden temperature changes, then turn on the kiln to let the bricks cool naturally.Allowing the bricks to cool naturally.The heat energy stored in the cooked bricks will not be used.which is a loss of heat energy.

DISCUSSION
Issue 1. Characteristics of the furnace square brick kiln model.The structure of this kiln is made of cooked bricks into a rectangular permanent wall.There is a firewood compartment and a brick entry door on the side.The top of the stove is mostly open.Production capacity is 50,000-100,000 bricks/stove.Arranging raw bricks in the stove will leave a space at the bottom of the stove for putting firewood.From the survey it was found that the specific energy was 1.6-3.8MJ/kg of brick, but some reports found that This type of stove uses energy up to 7.8 MJ/kg brick.The stove roof should be improved.Furnace wall/fire barrier wall Air ducts and the kiln floor.The other structures can continue to be used because the brick kiln is not complicated in nature.
Issue 2. Burning temperature Brick firing in Thailand usually ends at a temperature of 900 degrees Celsius approximately 20-150 degrees Celsius will mechanically expel water from the bricks.Up to a temperature of 900 degrees Celsius, vitrification will occur.(Vitrification) The strength of the brick will occur at this temperature.Issue 3. In terms of the burning time, approximately 7 days, it was found that the process of burning bricks in the kiln consists of 4 processes: baking bricks, warming bricks, burning bricks and reducing the brick temperature.The brick firing time depends on the amount of mechanical water.Water and carbon substances in the soil.

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-Removing water, burning using low heat.The hydration range depends on the mechanical water content and brick quantity in the kiln.This may take 2 days.Do not allow high temperatures to reduce cracking.
-Medium fire period is the process after the water has been removed by increasing the firing temperature to 650 degrees Celsius.
-During the high power period, the temperature is used up to 900 degrees Celsius.
-Temperature reduction period After finishing firing the bricks in the kiln, allow the bricks to cool down, which may take up to 3 days, depending on the weather conditions outside.Issue 4. Heat energy loss Brick firing in Thailand usually ends at a temperature of 900 degrees Celsius and is then turned off for the first few days at the end of the firing.To reduce cracking due to sudden temperature changes, then turn on the kiln to let the bricks cool naturally.Allowing the bricks to cool naturally The heat energy stored in the cooked bricks will not be put to good use.which is a loss of heat energy This type of burning uses a temporary kiln.This type of kiln burns one brick at a time.50,000-100,000 blocks will use rubber firewood as fuel.When burning is finished, the kiln must be allowed to cool down before the next fire can be fired.This is not continuous burning, resulting in a loss of heat energy and fuel value as a result.

SUGGESTIONS
As for domestic brick production, it is important to construction activities, especially in the provinces.It was found that brick burning uses a lot of energy.Most of them use firewood as fuel and the efficiency of the kilns used is quite low.It is likely that the efficiency of brick kilns will be improved or brick kilns with high thermal efficiency will be introduced.to be used as a replacement to suit local problem conditions to achieve high efficiency This allows the brick production industry to continue to exist.

Figure 2
Figure 2Dragon kiln Figure 5Forming construction bricks The chemical formula of clay is Al2O3.2SiO2.2H2O.Water is a chemical component of approximately 13.96% by weight, which is called combined water.The water mixed with clay is used in the process of forming raw bricks, which must be expelled during drying or drying of the bricks (drying).It is called mechanical water.The temperature that causes mechanical water to escape from raw bricks is in the range of 100-150 °C in firing clay bricks.It will remove mechanical water, compound water, combustible carbon and sulfur.(carbonaceous matter and sulfur) out of clay Decomposition of carbon substances contained in clay Carbonates contained in clay are impurities which can be decomposed by heat to form oxides and carbon dioxide (Rowden, 1964).Temperature 400-700 ° C FeCo3 = FeO + CO2 Temperature 400-650 ° C MgCo3 = MgO + CO2 Temperature 600-900 ° C CaCo3 = CaO + CO2 . Soc. Ambient.| Miami | v.18.n.7 | p.1-15 | e08399 | 2024.10 3.3 DATA COLLECTION Researchers went to interview the owner of the Moklan brick kiln factory Nakhon Si Thammarat Province on various issues.Bring the results from the interviews to gather issues for data analysis.

Figure 8
Figure 8Characteristics of the firewood compartment.