WO2001088343A1 - Mechanical and/or electric power production process using a combined cycle system comprised of an endothermal alternating engine and an exothermal turbine engine - Google Patents

Abstract

Process for producing electric power from the combustion of solid fuels on the one hand, by means of an external combustion machine (steam turbine) and fluid fuels, on the other hand, by internal combustion (alternating engine), by combining the thermal cycle of the second machine with the first.

Description

1- TITLE:

Procedure for obtaining mechanical and / or electrical energy by means of a combined cycle system of an alternative endothermic motor with a turbined exothermic motor.

2.- SECTOR:

Electricity production

3.- SUMMARY:

The present procedure consists in obtaining electrical energy from the use of solid fuels, on the one hand, by an external combustion machine (steam turbine) and fluid fuels, on the other, by internal combustion (alternative engine); combining the thermal cycle of the second machine over the first.

4.-BACKGROUND:

Until now, the obtaining of electrical energy has been carried out by combustion of primary energy by means of thermal machines to obtain mechanical energy and, subsequently, electrical energy. The thermal diagram would be as follows:

Residual heat

Energy Machine w Primary Thermal _f e ψ Mechanical Energy - Electricity

The thermodynamic laws establish that in any work process to obtain mechanical energy and, therefore, electrical energy, it has a lower performance than the unit, that is, that part of the primary energy invested, after the process, i

SUBSTITUTE SHEET (RULE 26) It will be in the form of residual heat. In addition, this work is obtained between two temperature levels, that is, thermal levels, one high and one other, lower.

The technique has taken care of maximizing the performance of these thermal devices using increasingly sophisticated machinery, obtaining the maximum production of electrical energy with the minimum consumption of primary energy, that is, minimizing residual heat.

Thermal machines are divided into exothermic or external combustion and endothermic or internal combustion. The exothermic ones basically consist of a combustion boiler plus a steam turbine, generally and, the most used endothermic ones are the gas turbine and the alternative engine.

Subsequently, modern engineering observed that in certain cases this residual heat was still at a high thermal level and, therefore, could be reused by combining the residual heat of the first machine over a second one operating at a lower thermal level , that is, between two lower temperature levels, the already known combined cycle.

This way of obtaining mechanical work has been carried out to date by combusting a single source of primary energy in the fluid phase and the type of machinery used to date has been "gas turbine" as a high-level thermal machine and "turbine of steam "as a machine that works with the residual heat of the first, that is, that operates at a lower thermal level, thus establishing a combined cycle.

The gas turbine has the disadvantage of obtaining a lower performance than the alternative engine, but it has the advantage that the residual heat emits it at a high temperature, around 6QQ ° C, sufficient thermal level to generate steam to move a steam turbine, obtaining, the latter, a good performance. Thus, the combination of both, achieves high performance on the inverted primary energy.

The scheme of operation that has been carried out until now, in combination of thermal cycles, would be the following:

SUBSTITUTE SHEET (RULE 26) Energy

Turbine Heat Primary gas boiler residual phase fluid phase recovery

Energy Turbine Mechanical heat of residual steam

Electricity Mechanical energy

Electricity

The combination of cycles has not been carried out until now with "alternative engine" + "steam turbine", since, despite the higher performance of the engine, it emits waste heat in two thermal phases, one at a high level, around 400 ° C and, another, at a low level, around 80 ° C. In any case, the high level is already lower than that of the "gas turbine". Roughly, these two heat items have an equivalent energy mass, being useful for a steam turbine, at most, the thermal phase at 400 ° C, although lower in performance than that of the "gas turbine", because the temperature is lower and, in no case, the phase at 90 ° C can be used, as this does not produce steam for the turbine. Thus, the combination of these two cycles is energetically unfeasible and, hence, has not been used in practice.

The operating scheme would be as follows:

SUBSTITUTE SHEET (RULE 26) Energy Primary motor alternative fluid phase Residual heat Residual heat at high level at low level

Energy Mechanical circuit Gases exhaust cooling

Electricity

Heat boiler residual recovery

Turbine Heat of residual steam

Mechanical energy

Electricity

Note also that the use of combined cycles has always been carried out with the same primary source of fluid energy.

5.- DESCRIPTION OF THE INVENTION:

The system that is provided as a novelty consists in obtaining electrical energy through the use of solid fuels, on the one hand and, of fluid fuels, on the other.

Solid fuels are burned in a boiler where steam is produced. This fluid is conducted to a condensation steam turbine that generates mechanical and, subsequently, electrical energy. The vapor condenses at low pressure inside a condenser and at a low temperature, around 45 ° C.

Fluid fuels are burned inside an alternative engine, also producing mechanical and, subsequently, electrical energy.

SUBSTITUTE SHEET (RULE 26) The combination of thermal cycles is performed as follows:

1) On the one hand, we have the high-level residual thermal phase that comes from the engine's exhaust gases, which leave around 400 ° C. These gases are taken to the interior of the boiler, we mix them with the combustion gases of the solid fuel, with which we achieve a thermal transfer of the residual heat of the engine, towards the external combustion boiler-turbine assembly, obtaining, as a consequence, a increase in the steam production of the boiler and, therefore, in the production of electricity in the steam turbine.

2) On the other hand, we have the thermal phase at low engine level in the engine cooling circuit at about 90 ° C. It is evident that with this temperature the water cannot be boiled, but what we do is use it to heat the water entering the boiler, at the outlet of the condenser that is around 45 ° C. Therefore, there is thermal transfer of heat from the engine cooling to the thermal circuit of the boiler-turbine. This has as an immediate consequence, a decrease in steam extraction to preheat the water entering the turbine, so that it will produce more electrical energy.

3) A small part of thermal energy is usually left over from the engine cooling circuit and, in our case, we use it to heat the combustion air of the boiler that is usually in the environment at about 20 ° C on average. And this is the third thermal junction between the residual heat of the engine and the boiler-turbine assembly. This thermal transfer results in a reduction of heat extraction in the combustion of the solid of the boiler that produces heat at a high level, using the heat of the solids directly for the production of steam, therefore, the heat introduced into the air Boiler oxidizer translates into an increase in the efficiency of the boiler and, therefore, in the production of steam and, consequently, electricity in the turbine.

Thus, we have managed to develop a system in which the low residual heat levels of the alternative engines compared to the gas turbine can be used in a combined cycle method by introducing them into the corresponding equivalent thermal levels of the boiler-turbine and , given that the performance of the "alternative engine" is higher than that of the "gas turbine", if almost all of its residual energy is used, it is obvious that the performance

5 SUBSTITUTE SHEET (RULE 26) on the primary fluid energy used, it is superior to the conventional set used to date "gas turbine - steam turbine".

On the other hand, we can see that the viability of the use of solid fuels is increased, so depleted in recent times, due to the cost of operation and the low yield on the inverted solid primary energy.

Note also that as a novelty the combustion of all types of fuels is provided with this system, whether they are in solid, liquid or gaseous phase, while with the traditional system "gas turbine - steam turbine" the introduction is not possible of solid fuels by conventional methods.

The scheme of the new combined cycle system will be as follows:

SUBSTITUTE SHEET (RULE 26) Primary energy Alternative fluid phase motor Residual heat Residual heat at high level at low level

Mechanical energy

Circuit

Exhaust gases cooling

Electricity

Steam circuit heating

Primary energy Boiler Heating water circuit solid vapor phase

Combustion air heating

Turbine Heat of residual steam

Mechanical energy

Electricity

SUBSTITUTE SHEET (RULE 26) 6.- DESCRIPTION OF A PREFERRED EMBODIMENT:

Solid fuels have, as main drawback, the cost of operation and its low efficiency. If we apply the new invented energy extraction method, we observe how the performance and, as a result, the profitability of a joint installation of solid and fluid fuel increases considerably.

The most appropriate system would consist of a steam boiler where solid fuel is burned. The steam would be driven to a condensation turbine and, as an internal combustion group, an alternative "Otto" cycle engine would be used.

7.- DESCRIPTION OF AN EXAMPLE:

The new energy policies lead to the use of renewable energy being, biomass, the pending subject in this process.

Biomass, like the rest of solid fuels, has as its main drawback in the extraction of energy, the operating cost and its low yield, forcing governments to encourage such use based on premiums and subsidies, in order to make viable its operation.

A suitable example would be the installation of a thermal power plant in which biomass would be used as main fuel and natural gas as secondary fuel.

The main machinery of the installation would be:

• A boiler of 22790 Kt of power consumption, of 23685 Kg / h of steam production, which feeds on biomass.

• A condensation turbine for 23 685 Kg / h of steam, which produces 4 804 KW _e of electrical power.

• An alternative Otto "cycle engine, which is powered by natural gas, 3 700 KW _and electric power, 9003 KWt of power consumption.

This set would consume 70% of energy in biomass and 30% of natural gas, measured by its P.C.I.

Well, of the 22 790 KW _t that the boiler needs to consume for the corresponding steam production associated with this power, 1 783 KW _{t would} proceed

8 SUBSTITUTE SHEET (RULE 26) of the engine exhaust gases, 1 583 KW _{t would} come from the cooling circuit of this apparatus to heat the inlet water to the boiler and 199 KWt would also come from the engine cooling circuit for heating the combustion air of the boiler. Thus, the biomass consumption of the boiler would drop from 2279Q KW _t , to:

Pb, lomasa = 22790-1 783-1,583-199 = 19225 KW _t

Seen from the motor side, of the 9 QQ3 KW _t invested in primary energy, 3 700 KW _e are obtained in the form of electrical energy, if we add them to the residual powers used on the side of the boiler we have a global use on the inverted primary energy in the form of natural gas of:

Amotor = 3700 + 1 783 + 1 583 + 199 = 7 265 KW

Given the approach from the perspective of electrical utilization we have that the 4804 KW _β produced by the turbine, come from the 22790 KW _t that are introduced into the boiler. If we distribute the electrical production of this turbogroup over each of the thermal sources, we have:

SUBSTITUTE SHEET (RULE 26) Thus, the proportion of electrical energy obtained in the turbogroup by, each of the above concepts, would be:

Which means that the electrical energy produced in the steam turbine, as a result of the combination of cycles, is:

P∞mbinado ^s 375 + 331 + 43 ^β 749 KW _e

It would be more correct to say that this electric power comes from the primary energy invested in the form of natural gas.

That is, the total electric power produced by natural gas would be:

Natural Pgas = 3 700 + 749 = 4449 KW _e

If the primary energy invested is 9 003 KW _t , we have that the electrical performance is as follows:

4449 η • 100 ^ 49.4% 90Q3

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SUBSTITUTE SHEET (RULE 26) A conventional combined cycle (gas turbine - steam turbine) running on the same fuel and the same amount, would not exceed, in the best case, 42% yield and, of course, with much more investment.

8.- CONCLUSIONS:

The main advantage of the system described lies in the high electrical performance obtained by associating the combustion of fluid fuels with solids by means of this new "combined cycle" system described, through conventional machinery; far superior to the performance obtained in combined cycles "gas turbine - steam turbine", without resorting to complex systems such as pyrolysis procedures, anaerobic digestion, gasification, etc. and, all this, at a lower cost of investment in capital goods.

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SUBSTITUTE SHEET (RULE 26)

Claims

9.- CLAIMS: 1) The object of the invention that is intended to be patented, consists in the process of obtaining electrical energy by means of a new combined cycle system, from the association of an external combustion machine for solid fuels (boiler-turbine) with a of internal combustion of alternative cycle for fuels in fluid state (motoaltemador); characterized by the thermal interconnection between the residual heat of the engine's exhaust gases with the combustion gases of the boiler, in the area of steam production and / or supply water secondary to the boiler and, the thermal link between the cooling circuit of the engine, with the primary feed water of the boiler and the combustion air of the boiler. Thus, most of the residual heat of the motor-alternator is transferred to the thermal circuit of the boiler-turbine. 2) Procedure for obtaining electrical energy by means of a new combined cycle system, based on the association of an external combustion machine for solid fuels (boiler-turbine) with an internal combustion cycle for alternative fuels in fluid state (motor-alternator) ); characterized by the thermal interconnection between the residual heat of the engine exhaust gases with the secondary boiler feed water circuit and the thermal link between the engine cooling circuit, with the primary feed water of the boiler and the oxidizing air thereof. Thus, most of the residual heat of the motor-alternator is transferred to the thermal circuit of the boiler-turbine. 3) Procedure for obtaining electrical energy by means of a new combined cycle system, based on the association of an external combustion machine for solid fuels (boiler-turbine) with an internal combustion cycle for alternative fuels in fluid state (motor-alternator) ); characterized by the thermal interconnection between the residual heat of the exhaust gases of the engine with the combustion air circuit of the boiler and, the thermal link between the cooling circuit of the engine, with the feed water of the boiler. Thus, most of the residual heat of the motor-heater is transferred to the thermal circuit of the boiler-turbine. The improvement of these three claims on the procedures of production of electrical energy for already existing fluid fuels, consists in the increase of the obtained electrical yield, on the primary energy of inverted fluid phase, to the 12 SUBSTITUTE SHEET (RULE 26) Take advantage of the internal combustion machine, the resources of the external combustion machine for solid fuels. 13 SUBSTITUTE SHEET (RULE 26)