[Gasification] ORC, gasifier, SRC systems at around the 2MWe level

[David Coote]

Hi Tom,

Turboden et al claim that the lower temperatures and pressures in an ORC 
system compared to an SRC system of similar size lead to reduced 
maintenance costs and - as a guy with a specialist high-pressure steam 
ticket is no longer required - also lower operations costs. I was 
wondering what you have come across which leads you to say below:

"The manpower and capital requirements are pretty similar for both the steam and ORC systems because of safety and other considerations."


What are the varied experiences with hot oil you mention? There have 
been some spectacular fires at thermal oil plants - there's a cracker of 
a YouTube video showing one from memory somewhere in the US NE - but the 
industry says that the newer oils are much less flammable

Thanks

David

On 3/02/2013 7:00 AM, gasification-request at lists.bioenergylists.org wrote:
> Message: 7
> Date: Fri, 1 Feb 2013 15:43:08 -0800
> From: "Tom Miles"<tmiles at trmiles.com>
> To: "'Discussion of biomass pyrolysis and gasification'"
> 	<gasification at lists.bioenergylists.org>
> Subject: Re: [Gasification] Gasification Digest, Vol 30, Issue 1: ORC,
> 	gasifier, SRC systems at around the 2MWe level
> Message-ID:<00f901ce00d5$e3b9ed10$ab2dc730$@trmiles.com>
> Content-Type: text/plain;	charset="us-ascii"
>
> David,
>
> Heat rates were calculated the American way, using HHV.:-)
>
> Steam and ORC was proposed in different configurations. A couple of
> companies proposed using backpressure turbines or steam engines with oil
> heated from the exhaust to drive an ORC turbine. Other proposed hot oil
> boilers and ORC turbines. The 20% efficiency of Turboden and others is 20%
> of the heat input to the turbine so you have to subtract the efficiency of
> converting the wet wood fuel to hot oil which runs from 62-72% of HHV
> depending on the MC of the fuel and the boiler configuration. Now since you
> have 70% of the heat input exiting the ORD as waste heat you need to dump it
> to a heat consumer. That work fine if you have an onsite heat consumer or
> district heat arrangement. Unfortunately most of our American towns are not
> laid out so conveniently that we can afford to build a district heat system
> for a small biomass plant.
>
> I agree that for all the literature on ORC there are very few head to head
> comparisons with steam of CAPEX and OPEX. The manpower and capital
> requirements are pretty similar for both the steam and ORC systems because
> of safety and other considerations. In the end the levelized cost of
> electricity (LCOE) will be higher for the ORC if you don't have a heat
> customer. If your need is primarily heat , or if you have waste heat
> available, the ORC systems look great. A new 2 MWe plant on Vancouver island
> with a PW/Turboden ORC uses oil from an existing hot oil boiler at a wood
> plant. There are many more hot oil systems in use in Canada than in the US.
> We have had varied experience with hot oil here.
>
> Tom
>
>
>