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Brick industry

Sector Highlights

Brick is a primary building material in many parts of Nepal, particularly in Kathmandu Valley and in the southern plain of Terai. Brick demand has increased dramatically over recent decades with the demand for housing. It is estimated that about 575 Brick kilns are in operation in Nepal. The capacities of these kilns range from 15,000 to 50,000 bricks per day. Clay is the main raw material for brick making, which is available at very low cost. Brick making is an energy and labour intensive process. Hand moulding of green bricks is widely practiced in Nepal and there is no mechanization of this process (except for large Hoffman Kiln units). The industry is seasonal and operates mostly for about six months from December to June again except for large mechanized kilns with shades for storing bricks.

 There are distinctly two types of brick industries namely the machine made bricks and handmade bricks. Most of the units in the country are handmade green brick making units. The kiln is mostly natural draft system or bull trench kilns (BTK). Moving Chimney BTKs (MC-BTK) that were the prevalent tchnologies in the past have been replaced by the fixed chimneys (FC-BTK) after the Government took steps to ban such units from the Kathmandu Valley. Apart from BTKs, there is also clamp, Hoffman and Vertical Shaft Brick Kilns (VSBK) in Nepal. Government has promulgated the standards on Chimney Height and Emission for the brick industries since 2008.

Table 1: Emission Standards and Chimney Height for Brick Kilns in Nepal

Process

Major process involved in brick making are Digging/Excavation, Clay preparation, Moulding, Sun drying, Stacking, Firing, and un-stacking/unloading. Hand moulding of green bricks is widely practiced in Nepal and there is no mechanization of this process (except for large Hoffman Kiln units). The industry is seasonal and operates mostly for about 6 months from December to June except for large mechanized kilns with shades for storing bricks.

Process flowchart for hand molded brick industry

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Process flowchart for machine molded brick industry

Energy Use

Nepalese brick kilns use mainly coal as energy resource which is imported from Assam in India. Apart from coal, a small fraction of sawdust/fire-wood is also used as fuel in these kilns. Brick making is an energy and labor intensive process. Approximate share of electrical and thermal energy used in brick industries in Nepal is presented below.

Major energy consuming section of the brick industry is the kiln where coal is used as an energy source for firing of green bricks. Electricity is mainly used for lighting. Few industries with mechanized moulding use electricity for clay preparation and moulding of green bricks.

Figure 1: Energy use in FC-BTK (GIZ/NEEP, 2012)

Conventional brick production is one of the largest energy consumers and air polluters in Nepal. VSBK technology consumes less energy and produces 30 to 40 % less CO2 emission, as compared to traditional production methods. Therefore, specific energy consumption of more efficient VSBK Kilns is considerable lower than in traditional FC-BTKs in Nepal (GIZ/NEEP, 2012).

Table 2: Specific energy consumption of different Kiln Technologies in Nepal

Figure 3: Handmoulding of green bricks (left); conventional coal feeding (middle); VSBK brick kiln in Nepal (right)

Figure 4: Functioning of a VSBK kiln

Beside the negative environmental impact, this labour-intensive sector carries a lot of health hazards as well as social complications, e.g. child labour, very bad working conditions, etc. Few years back the BrickClean Network was started by “concerned citizens” and non-governmental workers in Nepal to make brick consumers aware about the social and environmental impact of this industry. 

Figure 7: Criteria of BrickClean Network label in Nepal (BrickClean Network, 2012)

The overall objective of the network is to promote a socially responsible brick industry in the country, particularly working on eradication of child labour, improvement of living and working conditions of labourers, reduction of air pollution and other environmental impact and eradication of animal abuse. The BrickClean Network developed a voluntary label for the brick sector that gives an indication to the consumers how far a brick entrepreneur is considering environmental and social minimum standards.

References

  • GIZ/NEEP, 2012: Baseline Study of Selected Sector Industries to assess the Potentials for more efficient use of energy.
  • ESPS-DANIDA, 2000-2005: Cleaner Production report of brick industry
  • Confederation of Indian Industry: Investors manual for Energy Efficiency
  • BrickClean Network, 2012: The BrickClean Network Webpage. Available from: http://www.brickclean.net
 

Energy Saving Potentials

Major areas for potential energy savings in Nepalese in brick kilns are:

  • Improvement in heating system by installation of FD and ID fans
  • Improvement in heating system by adaptation of better technology (e.g. zig zag)
  • Minimization of heat losses from kiln wall, top coverage, doors
  • Improvement in combustion efficiency
  • Improvement in fuel feeding practice
  • Proper storages of fuel

The brick sector is one of the most energy-intensive industrial sectors in Nepal. In surveyed Fixed Bull Trench Kilns (FC-BTK) energy cost is almost 32 % of product value or total turnover; in Vertical Shift Brick Kiln (VSBK) it amounts to 14 % (GIZ/NEEP, 2012).

Figure 1: Energy cost on product value in % for different industrial sectors in Nepal (GIZ/NEEP, 2012).

In total Nepalese brick kilns units could save around 5,331,018 GJ thermal energy which means coal (see Table). Considering that most coal is imported from India and contributes to Nepal's huge trade deficit, energy efficiency improvements in brick kilns would reduce coal imports at considerably rate and, thus, the trade deficit with India.

By implementing energy efficiency the sector could achieve monetary savings of about 152,642 Crore Nepalese Rupees (GIZ/NEEP, 2012).

Table 1: Estimated energy saving potential in most important industrial sectors of Nepal (GIZ/NEEP, 2012).

Experience from the past have identified many options for improving energy efficiency in brick industries that are highly profitable, most of them with payback periods of investment of less than 1 year. The following table shows some implemented examples option in Nepalese brick sector with the respected payback (Danida/ESPS, 2005).

Table 2: Energy saving options for brick kilns and payback period (Danida/ESPS, 2005)

Energy Saving Tips

Brick making process has been divided into three processes:

In Nepal prominent share of firing technology is Bull trench kilns. As per experience there are significant losses which can be mitigated with small efforts. Following are the prominent areas of saving in fixed chimney brick kilns.

(1) Duct devise with double wall structure and insulation improvement( It Improve insulation and minimization of air infiltration within the kiln): In brick kiln duct, most of the brick kiln have single 14 inch wall with clay plastering results air infiltration from outside and heat loss from duct, results reduction in combustion efficiency and heat loss from the firing and soaking zone. This can be minimizing the proper wall construction .

Figure 2: Good duct wall design (left) and good insulation (right)

(2) Internal fuel (Fuel mixing with clay): Internal fuel addition significantly reduces. Cheaper fuels, such as, coal slurry, coal dust, charcoal dust, and sawdust can be used as internal fuels and can help reduce fuel cost. Management of internal fuel addition is extremely difficult in the manual molding process. Semi-mechanization of moulding needs to be promoted to support use of internal fuels. Semi-mechanization of the brick moulding process would have other benefits, including an ability to use inferior clay resources and wastes, reduction in drudgery and better working conditions for workers, and potential to produce hollow and perforated bricks.
(3) Control coal feeding - Reduction in spoon size and single man firing: It can saves energy with better combustion with correct air fuel ratio. Since within the duct there is constant air flow that means coal feeding should be constant and control .

Figure 3: Coal feeding practice (left); Use of small spoon (right)

(4) Improvement in Fixed chimney BTKs to Zig Zag kilns: Zig-zag kilns appear to be the logical replacement for FCBTKs, because of low capital investment, easy integration with the existing production process, and possibility of retrofitting FCBTKs into zig- zagfiring. The zig-zag kiln performance strongly depends on the kiln operation practices; also, zig-zag natural draught kiln appear to perform better than zig-zag forced draught kiln. These aspects need further study before finalizing recommendations and formulating a large-scale dissemination programme for zig-zag kilns.

(5) Air sealing in Wicket gate (Dawari): Leakage minimization in Wicket Gate leads on (see Fig.5 & 6):

  • Enhance combustion efficiency that means less energy (Coal) Consumption.
  • Improvement in Brick quality
  • Higher fire flow rate

Figure 4: Traditional (left) and improved (right) Wicket gate

Figure 5: Drawing improved Wicket gate

Further savings can be achieved by good housekeeping measures, improvement in combustion and insulation as well as the electrical system:

Housekeeping measures

  • Preventive/ Scheduled Maintenance of the Plant and Machinery
  • Improvement of storage system for raw materials and fuels
  • Capacity building / Awareness generation of the Firemen.
  • Optimization of Brick Stacking /Setting during loading.

Combustion and Insulation

  • Optimization of fuel Feeding System and improvement of combustion efficiency
  • Improvement of Insulation to minimize heat losses from kiln wall, top coverage, doors
  • Fuel switching if applicable.
  • Installation of Waste Heat Recovery System.

Electrical System

  • Minimising overall distribution losses, by proper cable sizing and addition of capacitor banks
  • Install delta to star convertors for lightly loaded motors
  • Install timers for automatic switching ON-OFF of lights
  • Install timers for yard and outside lighting
  • Grouping of lighting circuits for better control
  • Optimization of Water Pump system by careful selection of pumps in terms of capacity and application.
  • Install maximum demand controller to optimise maximum demand
  • Install capacitor banks to improve power factor
  • Replace rewound motors with energy efficient motors
  • Replace 40 Watts fluorescent lamps with 36 Watts fluorescent lamps
  • Replace conventional ballast with high efficiency electronic ballasts in all discharge lamps
  • Install LED lamps for panel indication instead of filament lamps
  • Install CFL's for lighting in non-critical areas, such as, toilets, corridors, canteens etc.
  • Replace V-belts with synthetic flat belts

References

  • GIZ/NEEP, 2012: Baseline Study of Selected Sector Industries to assess the Potentials for more efficient use of energy.
  • Danida/ESPS, 2005: Cleaner Production report of brick industry.
  • Confederation of Indian Industry: Investors manual for Energy Efficiency.
  • Central Bureau of Statistics (CBS), 2007: Census of Manufacturing Establishments carried out in the fiscal year 2006/07.
 
 

EEC Factsheet: Energy Efficiency for Brick Industries in Nepal - This fact-sheet summarizes energy saving potentials in Nepalese brick sector. It also give information on monetary savings by implementing energy audit and energy efficiency options in the industries. The fact-sheet is based on the findings of "Baseline Study of Selected Sector Industries to assess the Potentials for more Efficient use of Energy in Nepal" conducted by GIZ/NEEP Program in 2012.

Switch-Asia Project on VSBK and Sustainable Construction Practices (SCP) Nepal – The EU-funded project aims to contribute to the mitigation of global warming and environmental degradation by reducing greenhouse gases and black carbon emission, to foster sustainable (economic, environmental, social) production, to contribute to economic prosperity as well as to poverty reduction in Nepal. The project promotes energy-efficient VSBK-Technology and other sustainable construction practices in Nepal.