Cogeneration Scheme with a Partial Oxidation Gas Turbine in Belgium

CO-UTILISATION Co-Utilisation of Gasified Biomass, Refuse and Coal

PART 2

* Read the texts below to find answers to the given questions.

*• What is the way to reduce emissions of SO_z and CO,?

*•• What did the modification of an existing coal-fired plant in Finland allow?

³-What are the impacts of the innovative technology?

70 Section I. Power Engineering

Despite moves towards greater use of renewable sources to generate power, much of our electricity is still produced from fossil fuel sources, especially coal. One way to reduce emissions of S0₂ and C0₂ is to substitute' some of the coal used by conventional power stations with alternative fuels which produce lesser amounts of gaseous pollutants. This can be technically difficult, but the benefits of success are con­siderable in terms of a cleaner environment and long-term cost-savings ² for the consumer.

The modification of an existing coal-fired plant in Finland allowed 30% of the coal used to be substituted with biomass and refuse-de­rived fuels. Because burning biomass in a conventional power station is difficult and expensive, this has been achieved by installing a gas­ification unit. The gas produced by the gasifier has a very low heat value, especially if a fuel is wet. If, however, this lean gas is mixed with richer gas, produced from coal in the conventional part of the power station, the mixture can be co-combusted, and the need of an expensive fuel dryer is therefore removed. The CFB gasifier at the plant (30 to 70 MW capacity) is complemented by an innovative feed system, which makes it possible to adjust the moisture content of the gas mixture, to ensure optimum combustion conditions in the plant's boiler. The impacts of the innovative technology are al­ready apparent³in a decrease in emissions of C0₂, NO_x, SO_x and particulates. Implementation of similar projects could have a signif­icant impact in the fight against global warming and in making our environment healthier.

1 - заменить; 2 — снижение себестоимости; 3 - очевидный

1. What does this new project provide?

2. What is the effect of the integrated system?

A recent study, financed by the European Commission, concluded that there is a very real need for new technologies which can improve the efficiency of high temperature cogeneration (> 600° C). This new project provides for the demonstration of an innovative plant compris-

Unit 9. Fossil Fuels

ing a conventional "base" gas turbine (6 MW) with a newer Oxipar gas turbine (1 MW).

The Oxipar turbine is fed with compressed air from the base gas tur­bine, steam from the boiler and natural gas. It exhausts a combustible gas into a power turbine driving a generator, and then into the burner of a boiler. The effect of the integrated system is to raise the electrical efficiency from 18% to nearly 21%, for the same 80% global thermal efficiency. Expected costs per kW installed are about 20% lower than those of equivalent conventional systems.

JUST FOR FUN • Read and retell the text.

SCIENTISTS SMILE Exothermic ' or Endothermic ²

A thermodynamics professor gave his graduate students a take-home exam. It had one question: "Is hell (ад) exothermic or endothermic? Support your answer with a proof. Most of the students wrote proofs of their beliefs using Boyle's Law or some variant. One student, how­ever, wrote the following:

First, we postulate³ that if souls exist, then they must have some mass. If they do, then a mole⁴ of souls can also have a mass. So, at what rate are souls moving into hell and at what rate are souls leav­ing? I think that we can safely assume (предположить) that once a soul gets to hell, it will not leave. Therefore, no souls are leaving. As for souls entering hell, lets look at the different religions that exist in the world today. Some of these religions state that if you are not the member of their religion, you will go to hell. Since there are more than one of these religions and people do not belong to more than one religion, we can project that all people and all souls go to hell. With birth and death rates (уровни) as they are, we can expect the number of souls in hell to increase exponentially⁵. Now, we look at the rate (скорость) of change in volume in hell. Boyle's Law states that in order for the temperature and pressure in hell to stay the same, the ratio (соотношение) of the mass of souls and volume needs to stay constant-.

72 Section I. Power Engineering

# 1 — So, if hell is expanding at a slower rate than the rate at which souls enter hell, then the temperature and pressure in hell will increase until all hell breaks loose⁶, meaning that hell is exothermic.

#2 — Of course, if hell is expanding at a rate faster than the increase of souls in hell, then the temperature and pressure will drop until hell freezes over (замерзнет), meaning that hell is endothermic.

So which is it? If we accept the postulate given me by Therese Ban­yan during freshman year, and take into account the fact that I still have not succeeded with her, then #2 cannot be true. Therefore, hell is exothermic.

1 — экзотермический, теплопоглощающий; 2 — эндотермический, теплоот-дающий; 3 — допускаем; 4 — грамм-молекула; 5 — экспоненциально, по­казательно; 6 — выйдет из-под контроля

^^т unit ю ^^ш

NUCLEAR POWER

Дата добавления: 2015-05-08