The current economic situation makes many people think about optimizing budgets for repairs of process equipment, including power boiler equipment in terms of repairs, partial or complete replacement of refractory linings associated with scheduled or unscheduled repairs of boilers. These boilers operating on various types of bark and wood waste or agricultural waste (sunflower husks, etc.). Thus, in the current conditions, there is a completely natural desire of our customers to use the cheapest solution to save the repair budget, using refrac-tory bricks with the lowest cost on the market.
Please allow me to dwell in more detail - the lining is not just a refractory brick, it is a set of activities related to the design of the lining structure (single-layer, multi-layer), the selection of refractory (molded or monolithic or a combination of various types of refractory), the use of ordinary, shaped or piece drawing products. This is also the technology and quality of lining works, this is the use of high-quality materials that meet all the conditions of the production process. Once all above main factors are observed, it can be expected that the refractory lining will serve properly for a long time (on our boilers, Wellons boilers, the lining lasts 15 years & more).
Then what is the answer to a reasonable question, which we hear sometimes from specialists: “Why, subject to the above factors, the lining does not last more than a year?”. There can only be one answer – watch for the COMPLIENCE! We have carried out a large number of inspections of the lining of boilers and we see that one of the reasons for the destruction of the lining is the use of refractories that do not meet the criteria of the techno-logical process occurring inside the thermal unit. Returning to the question of the minimum cost of refractory, we can say that aluminosilicate brick of the ShB brand has one of the lowest prices on the market, but at the same time it has one of the lowest Al2O3 = 28% content (in fact, maybe a little more). And its use as a working layer in the fuel combustion zone in boilers running on various types of biofuels cannot guarantee its long service life due to low resistance to thermal shocks, to alkaline and abrasive aggression, low strength characteristics.
After that, is it possible to say that the low quality of the refractory brick of the ShB brand led to the destruction of this brick, despite the fact that all procedures for checking the quality of the refractory for compliance with the GOST requirements were carried out in the factory laboratory and the customer receives a quality certificate for this refractory - clumsy? Definitely not! If the customer independently decides to use a refractory that DOES NOT CORRESPOND to the operating conditions in a particular zone, without taking into account other destructive factors affecting the refractory by the processes occurring inside the unit, in addition to the temperature effect, then Responsibility for the service life of the lining as a whole falls on the shoulders of the customer. And in this case, the customer must be ready to carry out unscheduled restoration repairs and an early replacement of the refractory lining as a whole. In our experience, we see that in some boilers running on biofuel, the life of the lining, when using refractory bricks ShB, does not exceed one year! And with the proper selection of refractory and the implementation of all other measures for the design and installation of the lining, the service life of the refractory can reach at least 5-7-10 years or more. In our opinion, the use of aluminosilicate refractories with a minimum Al2O3 content of less than 40% in biofuel boilers is irrational. The presented photographs show typical defects in the lining of refractory bricks ShB in solid fuel boilers running on biofuel (refractory melting under the influence of temperature and slag effect on the refractory, chips, destruction under the influence of sulfur and alkali aggression).
Now, returning to saving the budget issue, everyone concludes for himself that it is more profitable for him to "save" the budget and annually carry out repairs / replacements of the lining on the boilers, or use the APPROPRIATE refractory and ensure trouble-free operation of the lining for a long time.