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Title:
A PROCESS FOR IMPROVING EFFICIENCY, WHILE ALSO DECREASING FLUE GAS EMISSIONS IN STATIONS PRODUCING POWER AND HEAT AND THE IMPLEMENTATION SYSTEM OF THIS PROCESS
Document Type and Number:
WIPO Patent Application WO/2007/132312
Kind Code:
A3
Abstract:
A dried fuel process brings an efficiency increase and at the same flue gas emission decrease during the process of producing electrical energy in big power stations and heat and power stations that are fired with brown coal or other solid fuels, is achieved by in drying coal or other solid fuel before energetic cycles, mainly before the combustion process, where the water separated from the coal through drying is drained during the cycles. The dried fuel process employs heat obtained directly or indirectly from steam that was used for running the turbine (T). Positive heat is obtained from the steam cooling installation that was used for running the turbine (T). Positive heat is obtained from the steam installation that was used for running the turbine (T), between the turbine (T) and the condenser (S). Positive heat is obtained from the condensate installation between the condenser (S) and the boiler (K). Positive heat is obtained from the cooling system located between the condenser (S) and the cooling tower (CK) or heat exchanger, or water tank. Positively, all foresaid resources can feed the drier at diversified combination. The system for implementing this method by adds a fuel drying system to recently operated power and energy systems relieving humidity from fuel. The drying system is fed with heat obtained directly or indirectly from steam that was used for running the turbine (T).

Inventors:
BUDZINSKI DARIUSZ (PL)
KURLAPSKI ROMAN (PL)
Application Number:
PCT/IB2007/001161
Publication Date:
June 03, 2010
Filing Date:
May 04, 2007
Export Citation:
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Assignee:
BUDZINSKI DARIUSZ (PL)
International Classes:
F01K17/06; F26B23/00; F26B23/02
Domestic Patent References:
WO1992014802A11992-09-03
WO1982003224A11982-09-30
Foreign References:
DE3433313A11986-03-20
DE19518644A11996-11-21
GB2014710A1979-08-30
US20060075682A12006-04-13
US4089657A1978-05-16
Attorney, Agent or Firm:
PSIORZ, Grzegorz (Szczecin, PL)
Download PDF:
Claims:

Claims

1. Directions for efficiency increase and at the same time flue gas emission decrease during the process of producing electrical energy in large power stations and heat and power stations brown coal or other solid fuels fired featured by the fact that prior to energy production cycles, and mainly before being fired, brown coal or other solid fuels are dried in driers (D) in such a way that water separated from coal by drying is relieved outside and fuel is dried with heat supplied directly or indirectly from steam that was used for running the turbine (T) or from its condensate.

2. Directions for claim 1, featured by the fact that heat is recovered from power producing steam's cooling system using the steam that was used for running the turbine (T).

3. Directions for claim 1, featured by the fact that heat is recovered from the power producing installation using the steam that was used for running turbine (T), prior to entering the condenser (S).

4. Directions for claim 1, featured by the fact that heat is recovered from condensate installation from power producing steam's installation using the steam that was used for running the turbine (T), prior to entering the boiler (K).

5. Directions for claim 1, featured by the fact that heat is recovered from cooling installation between the condenser (S) and cooling tower (CK) or between heat exchanger or water tank.

6. Directions for claim 1, featured by the fact that heat is recovered from combined resources listed in claims 2, 3, 4 and 5.

7. Directions for claim 1, featured by the fact that brown coal or other solid fuels are mixed with other solid combustible components after drying.

8. Directions for claim 1, featured by the fact that brown coal or other solid fuels are mixed with other solid combustible components before drying.

9. Directions for claim 1, featured by the fact that brown coal or other solid fuels are processed after drying to obtain either briquettes or granulated fuels.

10. Directions for claim 1, featured by the fact that brown coal or other solid fuels are soaked with vegetable, animal or mineral oil.

11. System for implementing the invention according to Claim 1, featured by the fact by adding a fuel drying system to recently operated power and energy systems removing moisture from fuel, where drying system is fed with heat obtained directly or indirectly from steam that was used for running the turbine (ϊ).

Description:

A process for improving efficiency, while also decreasing flue gas emissions in stations producing power and heat and the implementation system of this process.

The subject of this invention is efficiency increases at the same time that flue gas emission decrease during the process of producing electrical energy in big power stations and heat and power stations and the system for implementing this method.

Increasing demand for economically produced electrical power requires the improved efficiency of power producing installations. Other trials to increase electrical power production have focused on using circulation systems and seek to maximize the effectiveness of individual units through improvements or the addition of supporting system installations. With regard to the reduction of exhaust gas emissions they focus on removing effects rather than the root causes. One of the causes is the high moisture content of the fuel, mainly brown coal in which it can exceed 50%.

One of the cheapest means of producing electrical energy is power station output fired with brown coal that is easily accessible and relatively inexpensive. Low heat value resulting from high humidity causes logistic problems. As a matter of fact the moisture in brown coal reduces its energy properties especially its calorific or heat value.

Existing systems use brown coal which is powdered and pre-dried before being fired in the steam boilers to supply power to generator turbines. The intrinsic problem with this process is that the actual moisture reduction for brown coal does not a create a corresponding combustion efficiency increase because from the coal evaporated water as steam enters the boiler's furnace during combustion and is mixed with flue gases making up wet flue gas and reducing the energy transferred to the working medium, i.e. power steam. This phenomenon seriously influences the energy balance for power production and pollutant emissions that escape to the atmosphere.

The essence of this invention is increased process efficiency with simultaneous reduced flue gas emissions during the process of generating electrical energy in large power stations or heat and power stations that are fired with brown coal, consisting in drying coal or other solid fuel before energetic cycles, mainly before the combustion process, where the water separated from the coal through drying is drained during the cycles. Another important feature of this invention is the fact that the drying process employs heat obtained directly or indirectly from steam that was used for running the

turbine. Positive heat is obtained from the steam cooling installation that was used for running the turbine. Positive heat is obtained from the steam installation, which performed work in the turbine, between the turbine and the condenser. Positive heat is obtained from the condensate installation between the condenser and boiler. Positive heat may also be obtained from the cooling system located between the condenser and cooling tower or heat exchanger, or the water tank. Positively, all foresaid resources can feed the drier at diversified combination. An important property of brown coal is the fact that, when dried, it can be mixed with other combustibles or it can be dried as solid fuels mixture that is consist of difference solid components. Solid fuels can be processed after drying to obtain either briquettes or granulated fuels. Brown coal or other fuels are soaked with vegetable, animal or mineral oil. Another advantage is the system for implementing this method by adding a fuel drying system to recently operated and energy systems removing moisture from fuel. The drying system is fed with the heat obtained directly or indirectly from the steam that was used for running the turbine.

The subject of this invention is shown in the attached drawings where fig. 1 is the block diagram for the power production while figures 2, 3, 4, and 5 respectively show a dryer heat feeding installation between a condenser and cooling tower, between the turbine and before condenser, from condenser, and to carry condensate from the condenser back to the boiler. The diagrams depict a situation in which power stations fitted with cooling towers can replace them with a heat exchanger or water tank.

Brown coal, with the moisture level of 50% and more, is delivered to a power station, and then dried in special D dryers. The drying allows for producing fuel of improved quality and parameters. The drying of brown coal makes up for the fact that the moisture present in supplied brown coal is removed before the power producing cycles, because it is earlier returned to the atmosphere or is bled off as condensate. As a result it does not interfere with the combustion process. To illustrate let us assume the following data: brown coal with a moisture content of 58.1% has heat value 8.238 GJ/t; and brown coal with a moisture content of 21% has heat value 17.429 GJ/t. Thus, to produce the same amount of energy, it takes just 0.473 t of brown coal with a moisture content of 21%. This seriously influences the combustion and gas emission, as in order to produce 0.473 t of brown coal with a moisture content of 21% and heat value 17.429 GJ/t, 0.892 t of brown coal with a moisture content of 58.1% and heat value 8.238 GJ/t should be dried. This example proves that emission lowering depends directly on

decreasing amount of coal used for producing the same amount of power/energy.

However, the efficiency increase for producing power will result from the additional heat from the steam that performed work in turbine T. A basic thermodynamics principle states that the greater the temperature differential between boiler K and the cooler the more thermal energy taken from boiler K that can be converted into kinetic energy by turbine T. After leaving the turbine the steam can then be transported to the cooling system as waste heat or it can be utilized for drying fuel as outlined in this invention. Evaporated in drying process water, due to the fact it is vaporized at quite low temperatures, is inactive or neutral to the natural environment. Efficiency improvement will result also from decreasing outlet loss which is also known as loss in the flue gas. Loss in the flue gas depends mainly on the amount of flue gas. The less moisture in the fuel the less flue gas, which reduces loss in the flue gas and enables greater system efficiency. By using properly dried brown coal before the start of the energy cycle results in an efficiency increase for pulverizing mill where coal is pulverized and fed into the boiler K furnace in combination with heated air. Coal firing in the boiler K furnace produces superheated steam that runs turbine T. After the steam goes through turbine T it is condensed in condenser S and that condensate is pumped with feed water pump P 0 to boiler K where it regains its high parameters.

Energy balance would not be economical if additional energy were required for drying brown coal. In the process of generating electrical energy is produced the heat that utilize is troublesome. This heat should be reclaimed from steam that performed work running turbine T. This is low-parameter steam with a temperature of 40° C, which is reused when it's condensed into liquid form that is fed into boiler K. Therefore condenser S is in the power station's recirculation system to remove heat from the steam. Depending on the cooling system, heat is transported to environment in cooling tower CK in a closed circulation system or to a river in an open circulation system.

This invention provides several options for recovering heat from cooling system: condenser S and cooling tower CK, heat exchanger G in the water tank for closed circulation, or between condenser S and outside water sources for open circulation. It is also possible to recovering heat directly from condenser S into an energy dispersing system. Heat can be recovered both by a heat exchanger placed in at any point in the cooling system or by directing some or all of the water to the heat exchangers in drier D. After the heat is recovered the condensate is returned to the cooling system. Several other configuration options can be employed for heat collection directly from energy

circulation, viz. from the return part of the installation running to boiler K. In this case heat collection is possible from between turbine T and condenser S, from condenser S or from installation carry condensate between condenser S and boiler K. The manner in which heat is collected can be adapted to correspond to system requirements. It is also possible to combine the above methods of feeding the drier.

In all cases heat comes directly or indirectly from the steam that was used for running the turbine T. It is important to note that heat for feeding drier D comes from that steam or condensate prior to entering the boiler and that would otherwise be lost in cooling tower or water tanks.

To recap, the above solutions can be applied for heat and power stations. Drying procedures can cover not only brown coal but also hard coal or other types of solid fuel. Brown coal and/or other solid fuels are mixed after drying with other solid combustible components. In another version, brown coal or other solid fuels are mixed with other solid combustible components before drying. Fuels prepared that way can be fed directly to power producing units, but can also be processed to be granulated or made into briquettes after drying. Additionally high heating value can be obtained by soaking the fuel with vegetable, animal or mineral oils depending on system needs and capabilities.