RU2315233C2 - Method and device for generating steam - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: method comprises using agents that are vapors under normal conditions, e.g. nitrogen, oxygen, and air, burning out or solidifying the agent before using, and burning out the fuel in a pressure-tight space filled with the agent. The steam is supplied to the turbine or piston expanding machine. The vessel filled with the fluid and combustion chamber represent a single pressure-tight tank in which a mixture of the fluid and combustion products is generated. The control system automatically controls the temperature and pressure of the mixture. The heat energy of the exhaust steam is used for evaporation and heating of the fluid.

EFFECT: enhanced efficiency.

4 cl, 1 dwg

Description

The invention relates to the field of vehicles and power engineering, in particular to steam power plants.

Two main methods are well known for generating working gas or steam, carried out respectively in gas and steam cycles to produce mechanical energy.

The method of generating working gas in modern engines is based on burning fuel inside a compressed working fluid that is in a gaseous state throughout the cycle, far from the saturation line. The disadvantage of this method is that the gas cycles of internal combustion have a large degree of imperfection with respect to the reversible Carnot cycle and a large irreversibility due to high temperatures, and also spend part of the obtained mechanical energy on the preliminary compression of atmospheric air. The consequence of these drawbacks is that most of the energy of burning fuel is not used to produce mechanical energy and is released into the atmosphere.

The method of generating working steam in steam cycles is based on the use of working fluids whose aggregate state changes in the cycle: in one part of the cycle, the working fluid is in a liquid state, in the other part in the form of a two-phase mixture (wet steam), in the third - in the form superheated steam. Usually superheated steam is in states so close to the saturation region that the laws of an ideal gas are not applicable to it. The energy of the burning fuel is supplied by heat exchange in the boiler. Despite the fact that the use of a working fluid that changes its state of aggregation during the cycle allows the Carnot cycle to be implemented in practice, in this method of generating most of the energy of the burning fuel is not supplied to the working fluid due to the low exergy efficiency of the boiler.

Known piston internal combustion engines operating on gas cycles of Otto, Diesel and Trinkler, as well as gas turbine plants operating on various gas cycles. These devices are more or less ineffective for reasons inherent in the working steam generation method described above.

Thermal power plants are known with the generation of working steam from a working fluid, which is in a liquid state at atmospheric pressure and room temperature. These devices can operate in different cycles, but all of them are united by the presence in their composition of a boiler having a low exergy coefficient of performance (Kirillin V.A. et al. Technical Thermodynamics, M., Energoatomizdat, 1983).

The closest technical solution (prototype) is a gas-vapor combustion chamber of engines (Alekseev G.N. General heat engineering: Textbook, M., Higher School, 1980).

This device implements an improved method for generating working gas in the cycle of a gas turbine installation. Injecting water into the combustion chamber lowers the maximum temperature, making the gas cycle closer to the Carnot cycle.

In the gas-vapor combustion chamber, kerosene is fed through the nozzle, and air (or another oxidizing agent) is supplied through the many openings of the top cover. The combustible mixture is ignited by the ignition device. Below the flame front, water is injected through a system of nozzles with small holes at the ends. After mixing with the combustion products, vapor gas forms, which is fed into the turbine or piston expansion machine.

The efficiency of a combined-cycle combustion chamber is somewhat improved compared to a gas turbine plant. However, the temperature range in which this cycle is carried out does not allow to obtain a coefficient of performance in excess of 0.5. In addition, we can assume that it is difficult to change the operating modes of a combined-cycle combustion chamber in combination with the optimal dosage of fuel and water when the load changes in a turbine or in a piston expansion machine.

The objective of the invention is to increase the efficiency of energy use of combustible fuel in a steam-powered installation.

The problem is solved due to the fact that, as a working fluid, a substance or mixture of substances is used, which under normal conditions is steam, for example nitrogen, oxygen, air, which is preliminarily liquefied or solidified, and the fuel is burnt inside the sealed volume in which this substance is located . The generated working steam is supplied to the working body, for example, to a turbine or to a piston expansion machine.

This method of generation is internal combustion in the steam cycle of the working fluid. Moreover, the efficiency of this cycle is greater, the lower the condensation temperature of the substance of the working fluid. For example, liquid air, the triple point temperature of which is 64K, may well be used as a working fluid. In this method, all the energy of the burning fuel is supplied to the working fluid, and the cycle is as close as possible to the reversible Carnot cycle. In this case, the efficiency of the cycle with a heater temperature of 550 ° C (823K) is (823-64) / 823 = 0.92. Such a calculation is quite accurate, despite the fact that part of the cycle is close to the saturation line and does not obey the laws of an ideal gas. But most of the cycle is far from this line and the error in the first approximation can be neglected. At a temperature of 550 ° C, the materials of the steam power plant can operate without a cooling system, and the thermal insulation of the hot parts ensures a decrease in irreversibility in the cycle to a negligible amount. The energy remaining in the exhaust gases can be transferred to the working fluid for its evaporation and heating before supplying energy from burning fuel.

A steam-powered installation using the described method has a single sealed container formed by a combustion chamber with a cylinder containing a working fluid connected to it and a working body, such as a turbine or piston expansion machine.

To maintain optimal temperature and pressure of the working steam, there is an automatic control system for the supply of combustion components. The optimal values are: the maximum temperature for which the installation materials are designed (550 ° C); working steam pressure based on the safety factor of structures and saturated steam pressure of the working fluid (for air 350 kg / sq.cm).

The control system is an actuator, which, acting on the dispensers of the components of the combustion, limits or interrupts the combustion process when the set temperature or pressure of the working steam is exceeded and again ignites or increases the intensity of combustion when both the pressure and temperature become lower than the set value.

The diagram shows a general view of a steam power plant.

A steam-powered installation consists of a cylinder (1) containing a working fluid in a liquefied form, a combustion chamber (2) with dispensers (3), an evaporator (4), a control system (5), which includes an actuator (6) and sensing elements ( 7), and the working body (8). The cylinder (1) and the combustion chamber (2) constitute a single sealed container, closed to the working body (8).

Steam power installation works as follows. In the initial state, when the inlet of the working body (8) is closed, the cylinder (1) is filled with a working fluid in a two-phase state under the pressure of saturated steam, which also fills the combustion chamber (2). When the working body (8), the inlet opens. Saturated steam, diverging, lowers temperature and pressure. Sensitive elements (7) provide a signal to the actuator (6) for supplying and igniting combustion components. As a result of the start of the generation of working steam, its temperature and pressure rise. When one of these parameters is exceeded, the state of the working steam exceeds a predetermined optimal value, the sensitive elements (7) reduce the supply of combustion components or completely stop it. With the further expenditure by the working body (8) of the working steam, the temperature and pressure fall below the set value and the control system (5) again resumes the process of generating working steam.

Information sources

1. Kirillin V.A. et al. Technical thermodynamics. M., Energoatomizdat, 1983.

2. Alekseev G.N. General heat engineering: Textbook, M., Higher School, 1980.

Claims (4)

1. The method of generating working steam, which consists in supplying the components of combustion and the working fluid in a sealed volume for heating and removal of working steam to the working body, characterized in that as the working fluid use a substance or mixture of substances, which under normal conditions are steam, and before use - previously cured or liquefied. 2. The method according to claim 1, characterized in that the working fluid is heated. 3. A steam-powered installation using the method according to claim 1 or 2, containing a cylinder with a working fluid, a combustion chamber and a working body connected to a combustion chamber, characterized in that the combustion chamber and a cylinder with a working fluid comprise a single sealed container, and the cylinder with the working fluid is equipped with an evaporator connected to the exhaust outlet of the working body. 4. The steam power plant according to claim 3, characterized in that it is equipped with an automatic control system for the supply of combustion components to maintain the temperature and pressure of the working steam.