The problem of power generation under back pressure

The exhaust or exhaust steam of the back-pressure turbine generator set is generally used to heat the water in the user's heating to achieve the purpose of heating. The steam turns into water and returns to the boiler. Reuse. So there is no steam loss.

The exhaust pressure is greater than.

Megapascal steam turbines. The exhaust steam can be used to supply heat or supply the original medium and low pressure steam turbines to replace the medium and low pressure boilers of the old power plant. The latter, also known as the front-mounted steam turbine, can not only increase the power generation capacity of the original power plant, but also improve the thermal economy of the original power plant.

The design value of the exhaust pressure of the back-pressure steam turbine for heating depends on the different heating purposes; The back pressure of a front-mounted steam turbine is often greater than.

2 MPa, depending on the steam parameters of the original unit. The exhaust steam is used in the heating system and then condensed into water, which is then pumped back to the boiler as feed water. The condensate of the general heating system cannot be all**, and the water supply needs to be supplemented.

The electrical power emitted by the back-pressure steam turbine generator set is determined by the heat load, so it cannot meet the needs of both heat and electric load. The back-pressure steam turbine is generally not installed separately, but runs in parallel with other condensing steam turbines, and the condensing steam turbine bears the change of electrical load to meet the needs of the external electrical load. The electrical power of a front-mounted steam turbine is determined by the amount of steam required by the medium and low pressure steam turbines.

The pressure regulator is used to control the inlet steam volume to maintain its exhaust pressure unchanged; The low-pressure unit adjusts its own steam intake according to the demand of the electrical load, thereby changing the steam exhaust volume of the front-mounted steam turbine. Therefore, the steam intake of the front-mounted steam turbine cannot be directly controlled according to the magnitude of the electrical load.

Since the power generation of the heating back-pressure unit is determined by the size of the heat load, it is suitable to be used in the occasion where the heat load is relatively stable, otherwise the adjusted exhaust steam turbine should be used.

Compared with the condensing steam turbine with very low exhaust pressure, the same power is emitted, and the amount of steam required is large, so the amount of steam required per unit power of the back pressure steam turbine is greater than that of the condensing steam turbine. However, most of the heat contained in the exhaust steam of the back-pressure steam turbine is used by the heat user, and there is no cold source loss, so from the perspective of the heat utilization coefficient of the fuel, the thermal efficiency of the back-pressure steam turbine device is higher than that of the condensing steam turbine. Because the back-pressure steam turbine can pass through a larger steam flow rate, and the first stages can use larger blades, the internal efficiency is higher than that of the high-pressure part of the condensing steam turbine.

Structurally, the high-pressure part of the back-pressure steam turbine is similar to that of the condensing steam turbine. The back-pressure steam turbine mostly uses nozzles to adjust the steam distribution mode to ensure that the efficiency does not change much when the working conditions change. Because the back pressure machine is often used in occasions with stable heat load, a single row impulse stage is generally used as the adjustment stage.