HomeBringing back memories

Bringing back memories

Junior Isles, Managing Editor

The newspaper headlines of “technical problems” with Alstom Power’s advanced turbines initially brought a sense of déjàƒ  vu. My first thoughts were ‘here we go again’, as I recalled memories of the problems GE encountered in the early 1990s when the first Frame 9Fs began commercial operation. If GE had had its problems, perhaps now it was Alstom’s turn.

Certainly all new technology encounters teething problems which often do not manifest themselves until they are run for extended periods in the field. However, it is how manufacturers ‘anticipate’ and solve these problems that is all-important.

The Alstom problem has arisen with the uprated B version of its GT26/24 gas turbines introduced a few years ago – the first of which are now in the field. Some 60-odd of the uprated version have been sold in addition to the 20 or so, of the A version. The A version has been ‘problem free’ as such.

But as Jim Thompson, marketing director of Alstom Power’s gas turbine and combined cycle division explained: “There isn’t a gas turbine on the face of the Earth that hasn’t had a bug here or there. The important issue is how quickly we can fix them and minimize the impact on our customers. We’ve already put into service a fix for the issue which was referred to in the recent market statement.”

The source of the problem has been traced to the second stage of the low pressure turbine à‚– the GT26/24 turbines use a sequential combustion system with two turbine sections. Above the rotating row-two stage of the LP turbine, there is a honeycomb sealing system and a heat shield system. On analysis, Alstom found temperatures which were higher than those calculated in the design. This called for cooling modifications in that area.

A fix is now in place on the first machines which are now up and running again. Modified cooling parts have been installed at the Enfield (UK), Agawam (USA) and Monterrey (Mexico) power plants. According to Alstom, early assessments indicate that the fix has worked.

The costs of the fix are associated with the cost of opening up the machine and putting it back together. Although these are minor, the real cost will be from the impact of delays in customers’ commissioning and operating schedules. Alstom expects to have a firm estimate on these costs by November.

Fortunately for Alstom it was a quick fix, so costs associated with delays should be kept to a minimum. “The time it took from identifying the problem to getting the machines back on line was pretty short à‚– just a couple of months. The [temperature] issue was discovered at Agawam at the end of June. By the first week of August we had the modification implemented in the first machine,” said Jonathan Lloyd, GT24/26 product manager.

It is perhaps slightly unfortunate, however, that this issue has arisen when the company is beginning to get marked success in the ballooning US market. It has seen a number of orders for GT24s over the last nine months in a market which is largely dominated by GE and Siemens Westinghouse.

But markets like the US, where turbines cannot be installed fast enough, are part of the reason why we will continue to see generators experience debugging issues in the field. Bringing products to market quickly can sometimes involve a manufacturer taking risks with some components.

To expect a unit to undergo full extended periods of testing in this increasingly competitive environment is perhaps no longer realistic. Manufacturers will therefore have to find other ways of bringing products to market quickly while minimizing risk. According to Alstom, a key reason why it was able to instigate a quick fix was because it had made design allowances in certain components which allowed the machine to still be put into production quickly.

No doubt anyone with a long enough memory will have learned from those early GE experiences and turbine manufacturers will be all the wiser for it. On the customer side there will also be more information available as industry user groups are established such as the one formed by DERA and the Boyce Consultancy (see page 15).

Anyway enough of gas turbine memories. With this issue of PEi put to bed, at last it’s time to reflect on some far more interesting memories à‚– a recent holiday (with the boys) in Barbados.