Electric generating set small side road system and control method thereof

Abstract

A small bypass system of a generator set is provided, wherein the generator set at least comprises a boiler (1), a steam turbine (12), main steam pipes (13) connecting the boiler (1) with the turbine (12), and big bypass regulator valves (6, 7, 8, 9), the small bypass system comprises the steam pipes of the small bypass and at least a set of small bypass regulator valves (10, 11). A controlling method of the small bypass system is provided, which includes the steps that: firstly, before the big bypass system is opened, the small bypass regulator valves (10, 11) is opened gradually, until the small bypass system reaches the maximum rate of flow; secondly, after the small bypass system reaches the maximum rate of flow, the big bypass system is regulated to the degree corresponding to the maximum rate of flow of the small bypass system, at the same time the small bypass regulator valves (10, 11) is closed; then after the big bypass system reaches a bigger degree, the small bypass regulator valves (10, 11) is regulated to the maximum rate of flow gradually. The security of the generator set is enhanced and the starting time of the generator set is shorten by setting the small bypass system.

Description

technical field [0001] The invention relates to the field of electric heat engine and thermal automation, in particular to a small bypass system and a control method thereof. Background technique [0002] Coal-fired generating sets mainly include three main engines: boiler, steam turbine and generator. In the control strategy, the bulky boiler has a relatively large inertia of state change, and the change speed is relatively slow. The speed of change of the rotational speed and output state of the steam turbine is much faster than that of the boiler state. In the process of cooperating with the coordinated operation of the two, the bypass system is an indispensable part. [0003] At present, the large-capacity bypasses of domestic and foreign coal-fired generating units, including 100% capacity bypasses, are all directly drawn from the outlet pipe of the boiler superheater header close to the boiler side and then connected to the cold section of the reheater, which leads t...

AI Technical Summary

Problems solved by technology

In cold start-up conditions, the thermal shock causes the oxide scales that fall off the pipe to directly enter the high-pressure cylinder of the steam turbine, thereby causing great damage to the turbine blades

[0004] Second, when the unit is started, a large amount of foreign matter such as scale and solid particles will pass through the large bypass valve with the high-speed steam flow. The gap between the valve seats is very small, and the flow rate here is very high, and the solid foreign matter carried by the high-speed gas will erode the valve core of the bypass valve at a high speed, which will easily cause wounds on the valve core of the bypass valve.

However, when the valve core returns to its seat, the seal between the valve core and the valve body with the wound is significantly reduced, and the high-speed air flow will continuously wash away the wound, resulting in a continuous enlargement of the wound. In serious cases, the very expensive valve core will be scrapped directly.

At the same time, a large amount of steam will leak from this wound during operation, which will affect the economical operation of the unit

[0005] Thirdly, under normal circumstances, there is a period of start-up process with bypass when the unit is started. At this time, the main steam enters the cold section of the reheater through the large bypass valve and returns to the boiler reheater. During this process, when the steam passes through When the bypass valve is large, all the pipes from the large bypass valve to the steam turbine can only pass a small amount of steam through the trap, which will cause a considerable lag between the temperature of the main steam pipe in this section and the real main steam temperature

Moreover, the quality of the steam sampled from this section of the pipeline is not true, which makes it difficult to meet the conditions for the steam turbine to run, thus delaying the start of the steam turbine and wasting a lot of fuel, power consumption and time

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