Changes in how facilities are powered are driving a change in how existing equipment is used. For the heat recovery steam generator (HRSG) market, this is a good thing – and a challenge.
The good news for the sector is that business is increasing. MarketsAndMarkets reported in February that the global maret was valued at $714.4 million in 2014. From that base, the firm said, the category will experience a combined annual growth rate (CAGR) of 3.7 percent from 2015 to 2020. The driver, according to the firm, will be increasing overall demand for electricity, the growth of heat recovery steam generating and the growth of combined heat and power and combined cycle power plants (CHP and CCPP).
HRSGs capture heat that is produced by steam generation. That heat is re-purposed and drives overall energy efficiency. The secondary use can vary, from heating water used by residence in an apartment building to driving heavy machinery in an industrial plant.
John Susong at Industrial Access provides more detail on what HRSGs are and how they fit in:
HRSGs recover the heat from a hot gas stream produced by gas turbines, then turns that heat into steam. The steam can be used to generate electricity in order to create power or run a combined-cycle power plant. In the cogeneration mode, steam produced from the HRSG is mainly used for process applications, whereas in the combined-cycle mode, power is generated via a steam turbine generator.
The implementation of HRSGs in new approaches to power is tricky and can have complications. Jack Sine, a freelancer writing at Power, suggests that the transition from the main power source to one that is used for backups for wind, solar and conventional types of power plants causes difficulties. The details are technical, but the big picture is that changing equipment’s operational mode must be done with great care:
A lot of water can condense in HRSG superheater and reheater sections, and it can be problematic to drain the water. If the water isn’t drained, it can cause damage to the boiler’s tubing, resulting in expensive repairs and major downtime. This has been a chronic issue with these boilers for many years. Now that they are being cycled more frequently, the problem has become even more critical.
The issue seems to be that HRSGs were designed to marathon runners, while the new uses – as backups that have to start and stop often – demand that they act as sprinters. The industry to some extent is playing catch up, Sine writes. Rules and regulations don’t cover this type of operation, though the feature says that manufacturers are adapting.
The interesting ongoing issue is that HRSGs are being used in ways that are subtly different than that for which they were designed. Besides requiring changes to how they are managed – as Sine suggests – it also means that they now play a role in new approaches to energy generation. Today, Onward State – the website of Penn State University – reported that as of next month the school will use no coal. That’s a big deal: Penn State had relied on coal since it was founded in 1855. The decision to move to natural gas was made in 2011.
The story points out that the school has used a combustion turbine and HRSG since 2010. The system, which is almost 50 percent more efficient than legacy systems, pumps captured waste steam through 17 miles of pipes to heat campus buildings.
The role of HRSGs is great, growing – and in some cases changing. The ability of a technology to adapt to new roles is a key to its long term success. At the same time, however, the new ways in which HRSGs are used will lead to changes in how they are managed and cared for. Energy managers must pay attention.