Finned tube low-pressure economizer system using boiler waste heat

Abstract

A finned tube low-pressure economizer system using boiler waste heat comprise a water inlet pump (1), a low-pressure heating area I (2), a low-pressure heating area II (3), a low-pressure heating area III (4), a recirculating pipe (5) and a low-pressure economizer (6). The system is characterized in that the recirculating pipe (5) is parallelly connected between the low-pressure heating area I (2) and the low-pressure economizer (6), the condensate entering from the water inlet pump (1) passes the low-pressure heating area I (2) and the low-pressure heating area II (3) and flows out from the low-pressure heating area III (4), the outlet and inlet water temperature of the low-pressure economizer (6) is adjusted through an inlet water temperature adjusting valve (10) and automatic opening and closing of the recirculating pipe (5), and the outlet water temperature of the low-pressure heating area I (2) is allowed to meet the requirement. By the finned tube low-pressure economizer system, low-temperature corrosion is lowered, the service life of the low-pressure economizer is prolonged, and the low-pressure economizer is allowed to be in the optimal waste heat recycling state.

Description

technical field [0001] The invention relates to the field of boiler waste heat utilization, in particular to a finned tube low-pressure economizer system for boiler waste heat utilization. Background technique [0002] The low-pressure economizer is the exhaust waste heat utilization equipment used in recent years. Conventional low-pressure economizer has the same structure as ordinary economizer, but its connection system (working fluid side) is different from other economizers on the boiler. Its working fluid inlet and outlet are connected to the low-pressure heating area of ​​the steam turbine thermal system (hence the name), that is, the condensed water from a certain level of low-pressure heater, part (parallel system: and in one or several low-pressure heating) or all ( Series system; connected between two low-pressure heaters) enters the low-pressure economizer arranged behind the air preheater for heating, and the heated water returns to the low-pressure heater syst...

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Problems solved by technology

Conventional low economizers have the following disadvantages in operation: the first is the problem of corrosion

Because it is arranged in the low smoke temperature area at the tail of the boiler, corrosion will inevitably occur. Although the design can consider controlling the metal wall temperature in the second corrosion area (corrosion amount <0.2mm / year), if the coal quality is variable and The boiler undertakes peak-shaving tasks or long-term low-load operation, etc., so that the actual operation cannot meet the conditions proposed in the design, so the heating surface will be corroded and affect the life of the equipment; secondly, because the wall temperature should not be too low to meet the corrosion conditions during design, Therefore, the water temperature at the inlet of the low-pressure economizer is designed to be relatively high (acid dew point +10°C), so that it is impossible to greatly reduce the exhaust gas temperature, and the recovered waste heat deviates from the optimal state

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