From wet to dry in a cold climate

June 15, 2015 Claus Hagen Jensen

One of the biggest challenges facing cement plant owners in Russia lies in the type and quality of the raw material extracted from quarries. It is no different for JSC Sebryakovcement, whose raw material has a moisture content of approximately 20 percent. Traditionally, the raw materials (chalk and clay) need to be ground with water to produce a slurry with a 36 percent moisture content making it easy to pump into the kilns.

But this is an energy-consuming process. An economically viable solution was needed to replace two of JSC Sebryakovcement’s wet-process kiln lines that dated back to 1953. Sergey P. Rogachev, General Director at JSC Sebryakovcement explains the reasons behind the construction of a new dry process line with a clinker-producing capacity of 3575 tpd:

“The plant is located between two large cement markets in the European part of Russia. In order to sell a significant amount of cement on the markets, even competing with wet plants, it is essential for us to ensure the lowest production cost, since the transportation cost makes up a large part in the cement price.

New dry cement plants have emerged recently on the same markets, so it is vital our plant is as competitive as possible. Therefore, as part of the plant upgrade programme and reconstruction of all departments, the best means to bring down the fuel cost in the plant’s production cost structure was to convert the pyro-section from a wet to dry process.”

The ‘dreamline’ vision
The idea of a dry line at JSC Sebryakovcement is in fact not new. The plant’s first director and his colleagues had been dreaming about transforming the plant into a dry line. It was their common dream. That's why today, more than sixty years later, the line is affectionately known as the ‘dreamline’. But achieving the dream needed to be based on real business objectives, explains Sergey P. Rogachev:

“Our objectives included upgrading the plant infrastructure to achieve a steep reduction of fuel consumption and, consequently, production costs at the same time as maintaining the quality of clinker production. We also saw the opportunity for taking out of service the clinker burning equipment that had become inefficient, obsolete and worn-out.” - Sergey P. Rogachev, General Director at JSC Sebryakovcement

JSC Sebryakovcement needed to find an equally visionary partner who could meet the requirements of a demanding environment. The company had worked with FLSmidth on various projects since 2005, and it was a natural decision to continue the partnership.

Lower fuel consumption
Where the new dry line sets itself apart is in the concept of direct feeding to the kiln. The plant owners worked closely with the team at FLSmidth to design a solution that did not require the use of a raw meal storage silo, such as a CF-silo. This was one of the key reasons JSC Sebryakovcement chose FLSmidth, partly because of FLSmidth’s experience and reputation, but also because of its proven track record in producing innovative solutions to meet specific requirements.

Flow sheet of the new dry cement plant at JSC Sebryakovcement

The concept involved feeding the raw materials with their natural moisture content directly into the kiln system without grinding them to slurry. Since no further water is added as before, the overall heat consumption was reduced from the expected 1450-1500 kcal/kg clinker to less than 900 kcal/kg, which is the equivalent of more than 40 percent in fuel consumption savings.

A world first
A special feature of the raw materials, chalk and clay, is that  they are relatively homogeneous, regardless of where they are extracted in the quarry. It was this feature that led to the idea of producing the final mixture in storage. The chemical composition of the mixture is controlled by measuring the weight and analysing the bulk on the conveyor belt before storage. The intended chemical composition needs to be met before completion of a pile because no further chemical correction is possible.

In storage, the materials are stacked according to the windrow method made up of 10 layers split into some 20 rows. Cutting across these approximately 200 rows produces a high homogenising effect. Not only does this unique concept eliminate the need for a costly raw meal blending silo, but this combination of direct kiln feed with blending of all raw materials in storage has not been seen before.

First clinker was achieved in September 2013, less than three years after the contract was signed with FLSmidth. By December 2013, the performance guarantees were confirmed for the entire upgraded clinker line. The plant has now been running for more than one year with very high reliability.

​Operations at JSC Sebryakovcement have consistently outperformed performance guarantees

Local expertise
Satisfied that the plant can run at 3700 tpd, above the 3575 tpd target originally agreed, Claus Hagen Jensen, Project manager at FLSmidth, reveals why the issue of a cold climate is not actually a problem for the line’s performance:

“All parties took time during the design phase to ensure that lessons from other cold climate sites were taken on board. Everything was thought through very carefully to minimise any areas of doubt. Also, the team at JSC Sebryakovcement took an extremely professional approach to all aspects of the project. They went to great lengths to look ahead in order to foresee potential issues. This plant means a lot to the people who work there, and to the local community, which is why the plant’s management adopted a mind-set of wanting to prevent problems before they occur" - Claus Hagen Jensen, Project Manager, FLSmidth

In JSC Sebryakovcement’s new modern control room, plant operators oversee the dry process cement line operations

All performance guarantees achieved
Sergey P. Rogachev is pleased that his colleagues at JSC Sebryakovcement have quickly developed the necessary skills to operate the new dry cement line. And he is equally satisfied that all performance guarantees have been achieved. He puts this down to the experience and helpfulness of FLSmidth’s experts during the design, construction and commissioning of the plant:

“FLSmidth believed in our experience and jointly developed a unique production flow sheet enabling a significant reduction of the construction costs. The first year’s operation has proved that the flow sheet not only delivers the required clinker quality and a considerable reduction of the fuel consumption, but also lowers electric power costs compared to the ‘classic’ dry and wet processes.”

The equipment installed at JSC Sebryakovcement includes:


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