Brief introduction of direct air cooling system for generator sets

1. air cooling system of power station

1.1 single capacity of air cooling system

At present, the domestic and foreign power station air cooling is two kinds: one is the indirect air cooling system, and the two is the direct air cooling system. Among them, the indirect air cooling system is divided into mixed air cooling system and surface air cooling system. The world's first 1500KW direct air cooling unit in Germany in 1938, a pithead power plant put into operation, more than 60 years of history, the typical air cooling unit is put into operation, several: 1958 Italy air cooling power plant 2X36MW unit in 1968, Spain 160MW power plant put into operation of air cooling unit in 1978 in the United States, Wyoming Wodok power plant put into operation with 365MW air cooling 1987 South Africa Matimba power plant unit 6X665MW direct air cooling unit operation. Today, with the maximum capacity of single surface type condenser indirect air cooling system for South Africa Kendall station 6X686MW; the maximum capacity of single mixed type condenser indirect air cooling system for 300MW, currently in Iran operation of the 325MW (Harbin air conditioning Limited by Share Ltd supply) is running well. In the installed capacity of the air cooling unit in the world, the installed capacity of the direct air cooling unit is 60%, and the indirect air cooling unit accounts for about 40%.

1.2 characteristics of direct air cooling system

Both direct air cooling and indirect air cooling power plants have proved to be feasible after decades of operation. But do not rule out the air cooling system in operation, there are a variety of reasons caused problems, such as cold, hot and windy, the system design is not reasonable, improper operation and management.

Some of these problems have been solved, and it has been proved by the practice of 200MW air cooling unit put into operation in china.

Compared with air cooling system of power station, direct air cooling system has the main characteristics:

(1) high back pressure;

(2) due to forced ventilation fan, the power consumption is great;

(3) the forced ventilation fan produces great noise;

(4) the steel platform occupies less area than the reinforced concrete tower;

(5) efficiency than the indirect cooling system cooling area to about 30%, about 30% less than an;

(6) cost compared to economy.

2. composition and range of direct air cooling system

2.1 thermal system of direct air cooling system

The direct air cooling system, that is, the exhaust of the steam turbine enters the air condenser directly, and the condensed water is discharged into the regenerative system of the steam turbine by the condensate pump.

2.2 composition and range of direct air cooling system

Equipment and piping from the exhaust port of the steam turbine LP cylinder to the inlet of the condensate pump, including:

(1) exhaust pipe of low pressure cylinder of steam turbine;

(2) air cooled condenser tube bundle;

(3) condensed water system;

(4) pumping system;

(5) drainage system;

(6) ventilation system;

(7) direct air-cooled support structure;

(8) automatic control system;

(9) cleaning device.

3. the function and characteristics of each component of the direct air cooling system

3.1 row steam pipe

For large capacity air cooling unit, exhaust pipe diameter thick, South Africa Matimba power plant 665MW direct air-cooled unit 2 cylinder 4 exhaust, the exhaust pipe diameter of about 2XDN5000, the current domestic air cooling power plant design situation, row in DN5000 steam pipe diameter 300MW unit, 600MW unit steam pipeline in DN6000 about.

After the exhaust pipe is drawn from the A column of the steam engine room, the arrangement of the transverse exhaust steam pipe is arranged in two ways, one for low position and one for high position. It is difficult to optimize and manufacture the wall thickness of large diameter pipeline, and it is also one of the key factors that affect the cost of the project.

Cooling device for 3.2 air cooled condenser

(1) A type architecture:

The general double row pipe bundle is composed of steel tube fins, which is anticorrosive surface zinc crossing. The single row tube is made of steel tubes and aluminum fins, brazed to the large diameter rectangular oval tube. The upper end of the utility model is welded with a steam pipe, and the lower end is connected with a condensed water header. Each of the 8 or 10 components constitutes a heat dissipating unit, each of which has a tube bundle of 59.50 to 60.50 angles to form a A type architecture.

(2) cooling element:

The cooling element, the fin tube, is the core of the air cooling system, and its performance directly influences the cooling effect of the air cooling system. Basic requirements for performance of fin tube:

The heat transfer performance of A. good B. good temperature resistance properties; thermal shock; C. good; atmospheric corrosion resistance of D. good e.; easy to clean dirt: F. enough voltage capacity, low pressure drop in the tube, the air side resistance g. smaller; mechanical vibration resistance ability of H. good manufacturing cost; i. low.

The cooling element of the air cooled condenser is a multi tube with a fin outside the garden tube, such as a Coriolis cooling element. It has developed into a large diameter elliptical tube, and rectangular fin is double row tube. Recently, large diameter flat tube fin has been developed, which is also called single row tube. It should be said that the three cooling elements have been successfully applied in the direct air cooling system. The production of steel multi row pipe is mainly German buck Dole (BDT) company, the domestic production base is located in Zhangjiakou city; production of double row tube is mainly German GEA (GEA) company, the domestic production base for air-conditioning in Taiyuan jetye company, Limited by Share Ltd of Harbin; the original Harmon of Belgium (HAMON) Company production of single row tube no, the domestic production line, last year was the headquarter of BDT merger, merger with BDT for the same company, in the two production lines in Tianjin, up to now, there are three kinds of pipe joint production line in the country, or independent production.

(3) the composition of double tubes

Elliptical tube steel fin, diameter of 100X20mm oval tube, welded round welded rectangular fin, tube at both ends of a semi Park, the middle rectangle. First, the fin distance of the inner side of the air side is 4mm, and the fin distance of the outer tube is 2.5mm. The pipe distance is 50mm, according to the size of the radiating area, the number of the pipes can be changed, and a plurality of tubes are formed into a tube bundle, each of the 8 or 10 tube bundles form a heat radiating unit, and the two tubes are about 60 degrees angle