The rock products industry requires custom-engineered solutions to meet its heavy debris and process ventilation requirements. Robinson Fans meets and exceeds the industry’s requirements. Robinson’s experienced and knowledgeable technical team is able to recommend solutions that meet the specifications of any installation.
The Robinson team minimized the downtime and maximized the efficiency of the air moving equipment for multiple rock products plants during its more than 100-year history.
A kiln induced draft fan would continuously “trip out” due to excessive vibration. After stopping the fan and sand- blasting the areas where buildup was evident, the fan could be restarted and run for another one to five weeks before another untimely ‘trip out.” The customer was losing thousands of dollars--not only in maintenance costs, but also in lack of production--every time the fan shut down.
Robinson technicians went to the jobsite with the tools and equipment necessary to analyze the fan system. The diagnostic testing included an impact test (Bump Test) on the fan foundation and the rotor and shaft assembly. Analysis was also performed on the support system for structural integrity. In addition, examination of dampers, expansion joints, bearing pedestals and oil film stiffness was made.
The findings of this testing led the technicians to conclude that the float bearing pedestal (steel) and foundation (concrete) were in a rocking mode horizontally (both axial and vertical). Robinson recommended that the entire support of the float bearing be increased in size and stiffness to eliminate the sensitivity to material buildup on the fan rotor. Robinson completed this testing in one day. Robinson’s technical service team analyzed the data and submitted a written report to the customer with our recommendations. Robinson enabled a valuable customer to solve what had seemed an insurmountable challenge.
This plant was experiencing a buildup of process material on the blades of their 117” Raw Mill Fan. This buildup was causing vibration problems and the fan was being shut down three to four times a week to be cleaned. When these shutdowns occurred, production was stopped.
Robinson worked on the problem in the lab, testing different blade angles until arriving at a satisfactory backward curved fan wheel for this application. Robinson Service had a crew remove the existing wheel and cut the old wheel from the shaft and hub for reuse. Robinson Fans concurrently built the new wheel and when the shaft and hub arrived, assembled and returned the new unit to the plant site. At the plant site, Robinson Service reassembled the fan to online status.
The plant put this unit back into production and the buildup problem no longer existed. This was accomplished through the utilization of the years of experience and highly trained people at Robinson who continually strive for excellence.
A Robinson customer’s preheater fan had to be shut down every two to four weeks due to excessive vibration. Robinson’s field service team was called in to diagnose the issue and recommend a solution. Through a series of vibration tests, Robinson’s technicians determined that the fan’s support structure was too flexible to handle the excitation caused by the buildup of material on the fan blades.
A series of channels was added to the support base and bearing pedestals at the locations where excessive flexing was occurring.
The fan now runs significantly longer periods of time and the costs of maintenance and lost production have been reduced.
Excessive wear to blades, center plate and hub bolts due to process material in the air flow. This fan is located inside and in an awkward location, making a rotor change-out a difficult and lengthy job.
Robinson Service provided and installed center plate wear pads made of 3/8” erosion resistant material. They removed the old hub bolts, replaced and torqued down new bolts, and added hub bolt covers for further protection. The leading edge of each blade was repaired by welding numerous passes and capping off with a final overlay of hard surface weld material.
All repairs were accomplished by working through the available access doors. The fan rotor did not have to be removed, reducing time in bearing tear-down and reassembly, realignment of equipment and crane rental.