现场性能测试的测试不确定度

摘要

Field testing of gas turbine or electric motor driven compressor packages requires the accurate determination of efficiency, capacity, head, or power consumption in sometimes less than ideal working environments. Nonetheless, field test results have significant implication for the compressor and gas turbine manufacturers and their customers. Economic considerations demand that the performance and efficiency of an installation are verified to assure the return on investment for the project. Thus, for the compressor and gas turbine manufacturers, as well as for the end-user, an accurate determination of the field performance is of vital interest. This paper discusses a method to determine the measurement uncertainty and, thus, the accuracy, of test results under the typical constraints of a site performance test, for compressors capable of variable speed operation. Namely, a method is presented which can be employed to verify the validity of field test performance results. Results are compared with actual field test results,using redundant methods. Typical field test measurement uncertainties are presented for different sets of instrumentation. The effect of different equations of state on the calculated performance is also discussed. Test parameters that correlate to the most significant influence on the performance uncertainties are identified and suggestions are provided on how to minimize their measurement errors. Results show that compressor efficiency uncertainties can be unacceptably high when some basic rules for accurate testing are violated. However, by following some simple measurement rules and maintaining commonality of the gas equations of state, the overall compressor package performance measurement uncertainty can be limited and meaningful results can be achieved.%燃气轮机或电机驱动的压缩机组的现场测试需要精确测定效率、容量、压头或在非理想的工作环境下的功耗.因此,现场测试结果对压缩机和燃气轮机制造商及其客户有重要意义.出于经济考虑,要求验证安装机组的性能和效率以确保项目的投资回报.因此,精准确定现场性能对于压缩机和燃气轮机的制造商以及终端用户非常重要.针对调速压缩机,讨论了一种确定测量不确定度的方法,由此确定在典型约束下的现场测试结果的准确性,即一种可用于验证现场测试性能结果有效性的方法.使用冗余方法把计算结果与现场实际测试结果进行了比较;描述了典型现场测试条件下不同仪表的不确定度;对不同状态方程对计算性能的影响进行了讨论;确认了对性能不确定度有显著影响的相关测试参数,并提供了关于如何使各参数测量误差最小化的建议.结果表明,当违反一些精确测量的基本规则时,压缩机效率的不确定度会超出可接受条件.然而,通过遵循一些简单的测量规则和保持气体状态方程的一致性,压缩机组总体性能测量的不确定度可被限制在一定范围内,并且可以获得有意义的测量结果.