Morocco Jerada O&M Project solved desulfurization system reliable operation problem


Since being operated from mid-May, the desulfurization system of Morocco Jerada O&M Project has been operating for more than two months. The bed pressure operation of the desulfurization tower is stable, the pressure difference of the precipitator is operated within the design range, and the sulfur content of the desulfurization tower meets the contract requirements, which means that the reliable operation of the project’s desulfurization system was solved successfully.

The Morocco 350MW coal-fired unit adopts the integrated process of dry desulfurization and dust removal. The system is mainly composed of flue gas system, ash circulation system, bag filter system, reactor system, absorbent feeding system and process water system. Since operating the unit, the desulfurization system has problems such as large fluctuations in bed pressure of the desulfurization tower, high pressure of the precipitator, poor operation reliability, and inability to automatically transfer, which leads to the problem of the long-term reliable operation of the desulfurization system and it has become a difficult problem for both the company and the project.

Prior to the minor repairs of this year, the project attached great importance to the reliability operation of the desulfurization system. In order to ensure that the desulfurization system can be put into normal use after the maintenance, the project set up a special research team to conduct research on similar equipment units in China on one hand, and on the other hand sort out the problems that restrict the operation of the desulfurization system, formulate treatment measures, and resolve to completely solve the problems of the desulfurization system.

The minor repairs were taken from late March to early April. The project strictly organized defect eliminating work for the desulfurization tower according to the established plan, and held special meetings to analyze the reasons that affect the reliable operation of the desulfurization system, checked and cleaned the desulfurization tower, the interior of the precipitator and the inlet and outlet flue, replaced the blown pipe elbow of the blown dust collector and the partially damaged dust bag, carried out tracking test for the return control valve switch, and completely cleared the fluidized air pipe of the circulating ash system, and completed the empty tower pressure correcting work.

During the trial operation period after the minor repairs, the research team developed ideas and deal with the problem of the unsealed fluidized cloth at the return valve and optimized the system and adjusted the parameters. The position and injection angle of the desulfurization tower water spray device were modified; the bed pressure trip value and the process water pump protection trip value were optimized; the dust spray bag blowing logic and the bed pressure operation range were optimized.

In mid-May, the desulfurization system was officially put into operation. Up to now, the bed pressure operation of the desulfurization tower is stable, the pressure difference of the precipitator is operated within the design range, the returning system is operated normally, and the process water, feedstock, and flue gas recirculation systems are automatically put into operation, which greatly reduced the intensity of work for operation personnel. The sulfur content of the desulfurization tower is below 700mg/Nm3, which meets the contract requirements (below 850mg/Nm3). So far, the project’s desulfurization reliable operation problem was completely and successfully solved.