火炬烯烃设施的系统检查
Because of the critical role the ethylene unit emergency flare fills, it is one of the last unit process systems available for maintenance and one of the first required back in service after a unit turnaround. With such a short window for maintenance, the condition of the flare system must be understood prior to a unit turnaround. Flares can be inherently difficult to inspect because of the intense heat radiation and physical elevation. However, the flare is dedicated to the safety of the process equipment and the surrounding community and must operate as designed at all times. This paper will discuss the two different types of flare system inspections: in-service and out-of-service / turnaround, and keys to conducting them effectively to keep your flare operating as designed.
Abstract
When evaluating the safety and environmental aspects of an olefins facility one must surely consider the flare. The flare is responsible for safely combusting enormous amounts of flammable material during plant upsets and it must perform its designed function in an environmentally acceptable manner. Tolerances are tight and regulations are strict. A flare operating at less than peak condition typically will not perform to the design criteria, creating safety and environmental concerns.
Regular and effective inspection of the flare is absolutely necessary to ensure the safety and compliance of the facility. This paper highlights components of a proper flare system inspection process. The paper will address two basic types of flare inspections: in-service and shutdown. Each type of inspection has its own challenges and advantages.
In-Service Inspection
Prior to the 1990s, the petrochemical industry standard for flare system maintenance scheduling was based upon time in service rather than detailed inspection. Unfortunately, this approach did not take into account the actual mechanical condition of the flare equipment at the minute level. If flare problems were evident during operation or visible from a ground level inspection, then maintenance time would be built into the turnaround schedule. Upon investigation during the outage, addressing the maintenance issues previously observed would typically reveal additional problems. Discovering maintenance issues in this way usually leads to extended downtime. Facilities were essentially forced to have various spare and often expensive flare parts on hand, or plan for a replacement of their flare tip at every outage to avoid extended downtime during turnarounds.
Summary
Flare systems fill a critical role in the safe and environmentally compliant operation of an ethylene plant and therefore must operate as designed. Unfortunately, the useful life and performance of a flare are impacted by unexpected problems within the ethylene unit operations or supporting utility system. A combination of inspection approaches should be utilized in order to most effectively maintain and efficiently operate a large ethylene flare. In-service inspections are the right tool to help identify problems, schedule parts and prepare a turnaround scope of internal inspection or repair for a flare. The in-service inspection should be evaluated in conjunction with the flare OEM or other flare suppliers for an unbiased opinion. Some concerns raised during the in-service inspection may require more immediate attention while others identified can help define the scheduled turnaround scope and ensure needed parts are on-hand in advance.
Out-of-service inspection of the flare system will often yield unforeseen additions to the planned scope of work, but is necessary for proper inspection of internal engineered components. Some of these issues may be able to be deferred until the next scheduled maintenance window, while others will require immediate attention. Using both in-service and out-of-service inspections to proactively identify problems and plan necessary maintenance based on actual observed conditions reduces unplanned downtime and potential system failures.