Promoting Waste Heat Recovery Power Generation in Coal Gangue Brick Factories in China

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Contents

Summary

Successfully piloting technologies requires allocating sufficient time to allow for advocacy and replication activities. Completion of technical pilots can be challenging in short time frames, such as the three year window within which the Joint Programme functioned; advocacy and replication to promote sectoral-level deployment require longer time frames.

Purpose of the activity

The purpose of the activity was to pilot waste heat recovery power generation technology in selected coal gangue brick factories in China.

Original issue addressed by the activity

Coal gangue is the waste left over from coal mining and is generally made up of a variety of types of rocky waste, including – importantly – coal particles. It is often dumped indiscriminately during mining, creating huge hill-like mounds. The Government of China has been promoting coal-gangue brick production to promote the reuse of industrial wastes in industrial production as well as to protect existing agricultural land resources from further encroachments. It has been estimated that by the end of 2007, China had accumulated 5 billion tonnes of coal-gangue. In coal-gangue bricks, a percentage of the clay used to make the bricks is replaced by coal gangue. Not only does this reduce the demand for clay and reduce the amount of coal-gangue waste, it also reduces the coal requirements of the brick kilns because there are sufficient coal particles in the coal gangue to heat the kilns without the use of extra coal. The coal-gangue brick sub-sector is still quite small with an annual production of approximately 20 billion bricks, representing 2.2 percent of the total output of the entire Chinese brick sector. However, this figure is increasing rapidly, with the sector now consisting of approximately 2,000 brick factories across China.

Technology for waste heat recovery power generation is quite mature and is already widely deployed internationally and in China in sectors such as cement, iron and steel, coking and glass making. The purpose of the pilot programme was to promote application and deployment of these smaller waste-to-heat recovery power generation systems in the Chinese coal-gangue brick sector. The potential exists to recover waste heat from the brick kilns, to use the heat to produce high temperature and pressure steam, and then pass the steam through a turbine to generate electricity. The factories can use this electricity on-site for their own needs, cutting their electricity bills, or sell it to the grid. There is also an added benefit, in that companies reduce their climate change impacts by displacing many thousands of tonnes of greenhouse gas emissions each year.

Strategy chosen to address the issue

This project demonstrated the technology in two pilot companies, the first on a new brick line and the second on an existing line to demonstrate feasibility in both scenarios. The results will be demonstrated locally to other companies, along with the feasibility studies and a full assessment of technical and economic benefits with a view to promoting wider dissemination in China.

Implementation of the strategy

The results have been shared in various workshops including a national workshop for the construction materials industry which was attended by representatives of numerous brick-making factories.

Promotional materials have been developed both in English and Chinese, providing the details from the feasibility studies conducted on the two pilot enterprises, the types of equipment and systems they have deployed, a breakdown of how much their initial cost/investment was under the project and the internal rate of return so as to give an indication of profitability. The risks are explained along with information on the potential savings which are calculated separately and respectively for different production lines.

Challenges and Innovations

The technology which was previously widely deployed in other sectors and in much larger scale installations (typically 10-12 MW) such as iron, steel, cement and coke in China and elsewhere was successfully proven as feasible in the coal gangue brick sector, at a range of just 1-2 MW. The methodology created under the Joint Programme has been tested, proven and is now easily accessible to interested companies.

However, identifying pilots, demonstrating the technology and replicating results in such a short period of time was challenging. It was particularly challenging in the instance of the Joint Programme given that it coincided with the global financial crisis and many companies were struggling to just stay in business at the time. The first company approached by the Programme which agreed to participate in the pilot had to later withdraw for financial reasons. Construction of each of the pilots took approximately 9-12 months from design to commissioning, and implementation was delayed at both sites on different occasions due to poor weather conditions.

Results and Impacts

A post-commissioning assessment of the performance of the two pilots was conducted independently to help support further dissemination of results. Software which can be run from a CD allows potentially interested companies to conduct a preliminary test to get an indication of whether such technology might be feasible for them.

Since the Programme ended, a third and much larger 3 MW heat recovery power generation system has been constructed by another company affiliated with one of the first two pilots. This third installation was financed independently from the Programme through other sources of funding. The construction work has since been completed, the pilot commissioned and at the time of print, the system just went into normal operation.

Next Steps

The programme has now distributed materials to the sector, allowing others to proceed with their own installations.

Potential replication / application

HRPG technology offers great potential for energy savings in the coal-gangue brick sector, allowing up to 100 percent savings in costs and allowing companies some protection against fluctuations in prices while also reducing GHG emissions from electricity purchased from the grid. In particular, there are benefits for large companies including, for example, state-owned enterprises for which feasibility studies show a higher return for larger scale plants. Likewise, these companies would also have less difficulty mobilizing funds to pay for installation of such systems.

However, when considering potential replication of these waste-to-energy recovery schemes, and particularly with respect to piloting such technologies, consideration must be given to allowing adequate time for implementation, as well as flexibility in case of having to change plans during implementation. For the full cycle of site selection, designing, implementing, and allowing sufficient time to view results, our experienced shows that three years is a tight time frame. The major lesson learned therefore is to give due consideration to realistic time frames for full pilot programme implementation.

Information products

This lesson learnt has been adapted from “The China Climate Change Partnership Framework Occasional Paper”.

For details of the engineering feasibility study and full technical, economic and financial assessment of the pilot projects, etc. please see: Promoting the Adoption of Heat Recovery Power Generation in the Chinese Coal Gangue Brick-Making Sector Support Package and Best Practice Guide.

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