1、 Overview Chemical make-up water, condenser scientific make-up water, condenser water-saving device summary
TG TEG equivalent enthalpy drop method is a thermal theory developed in recent years. TEG condenser water supplement device is a key energy saving measure popularized by the Ministry of electric power. As a new calculation and analysis method of thermal system, it is simple, convenient and accurate in the quantitative analysis of local changes of thermal system. It is the theoretical basis of thermal system optimization and energy-saving transformation, which is of great significance for tapping energy-saving potential and improving energy-saving technology.
Therefore, while popularizing the enthalpy drop method, we analyzed the thermal system of some representative steam turbine generator units in some power plants. Based on the analysis results, we formulated the relevant scheme, and introduced the technology of "chemical water supply mode and energy saving improvement of thermal power generation system", and produced products for users.
2 Replenish water Feasibility analysis of system transformation Chemical make-up water, condenser scientific make-up water, condenser water-saving device
In this paper, taking B Ⅱ - 25 - 3 type high temperature and high pressure heating unit of a power plant as an example, the feasibility analysis of the transformation by equivalent enthalpy drop method is carried out
The machine is equipped with two high-pressure heaters and three low-pressure heaters. The make-up water system is a "deaerator type" make-up water system. The chemical softened water is added to the pressure resisting deaerator, and the high-pressure deaerator is fed by the relay pump. The water inlet and outlet modes of the low-pressure and high-pressure deaerator are all in the main pipe operation.
Under normal operation conditions, the heating load is 40-70y / h and 0.8-1.3mpa (see Fig. 1 for the principle thermal system diagram).
Through investigation and research, the unit rating and related parameters are given priority to, and the actual parameters are corrected, and the equivalent enthalpy drop method is used for analysis.
1. Feasibility analysis results of heat recovery:
Note: η 1 improves the efficiency of rear engine and η improves the efficiency of front engine Chemical make-up water, condenser scientific make-up water, condenser water-saving device
relative increase △%
For the unit, every 1% increase in vacuum can save 750 tons of coal in half a year.
Through the analysis of "equivalent enthalpy drop", we know that the advantages of "deaerator type" to "condenser type" are as follows:
① make up water is supplied from the condenser, and the flow path is shaft seal cooler. After the steam extractor is heated at low pressure, it reaches the high-pressure deaerator. In this process, the make-up water absorbs a certain amount of heat to enter the high-pressure deaerator by about 50% higher than the outlet water temperature of the low-pressure deaerator. As a result, the extraction capacity of the low-pressure system is increased, that is, the low-grade steam extraction capacity is increased; the high-grade steam extraction amount is reduced, and the work of this part in the unit is increased; at the same time, the heat transfer deviation in the heat absorption process of the make-up water is reduced, the irreversible loss in the heat transfer process is reduced, the heat work conversion efficiency is improved, and the heat recovery effect is obviously improved.
② the condenser carries out vacuum deaeration for make-up water, which improves the deaeration capacity of the whole regenerative system.
③ The make-up water absorbs the exhaust heat in the condenser, reduces a certain share of the balance loss, strengthens the heat exchange, reduces the exhaust temperature, and improves the vacuum of the unit. Moreover, when the make-up water temperature is lower than the exhaust temperature, the effect is obvious month by month, which is not only economical but also conducive to the load connection of the unit (generally speaking, the make-up water temperature of the thermal power plant is between 20 ~ 38 ℃)
III. determination of reconstruction scheme and relevant parameters of water supply system Chemical make-up water, condenser scientific make-up water, condenser water-saving device Determination of relevant parameters
in order to obtain better economic benefits, the following matters should be paid attention to when formulating the transformation scheme:
(1) selection of implementation scheme for water supply system.
according to the characteristics of the site system, the source of water supplement for the system should be selected, i.e. unit water supply or water supply from the main pipe, etc., and then the position and space size of the condenser throat should be determined.
② determination of water supplement amount. The amount of water added into the condenser is restricted by the following main factors:
that is, it is limited by the flow capacity of condensate pump, main steam extractor, shaft seal cooler and low-pressure heater.
(1) when the amount of water added into the condenser is too large, the condensate pump can not pump the water in the condenser in time, which will lead to full water and affect the safe operation of the unit. Therefore, the amount of water added into the condenser should not exceed the difference between the output of condensate pump and the amount of condensate water. To solve the above problems, another small condensate pump can be set up.
(2) the main steam extractor, shaft seal cooler and low-pressure heater are all rated When the flow rate exceeds its rated flow rate, the outlet water temperature will be reduced due to its sufficient heating capacity, and the regenerative effect will be weakened. Therefore, the amount of water added into the condenser shall not exceed the difference between the rated flow of the main steam extractor, shaft seal cooler and low-pressure heater and the water volume of the condenser.
Secondly, due to the limitation of deaeration capacity, the deaeration capacity of the determined unit and condenser water replenishment device is determined. If the make-up water is too large, it will not be able to reduce the oxygen content in the make-up water below the required value, resulting in excessive oxygen content in condensate, which will corrode the condensate pipeline.
In addition, during operation, the make-up water should match the load of the unit.
(3) introduction of improvement measures and relevant methods of water supply system: Chemical make-up water, condenser scientific make-up water, condenser water-saving device
(1) as long as the make-up water is flushed into the condenser, better heat recovery efficiency can be obtained.
② in order to improve the vacuum of steam turbine by absorbing exhaust heat in the condenser, the way and position of make-up water entering the condenser should meet the requirements of thermal deoxidization, so the water feeding mode is very important.
through evidence collection and analysis, we determined that the water supplement state should be atomized from the throat, and it is better to form a "atomization belt". Through selection, we designed and manufactured a kind of "mechanical atomizing nozzle".
The secondary nozzle can strengthen the heat transfer between the make-up water and the exhaust steam, so that the make-up water is easy to reach saturation, which creates conditions for the gas to overflow and diffuse from the water droplets, and at the same time, it prevents the phenomenon of make-up water flowing along the inner wall of the condenser.
To sum up, according to the size of the condenser throat, determine the way and location of the pipe layout of the "make-up device" in the condenser, and then determine the optimal position of the nozzle. After the above two items are determined, the injection angle of the nozzle is determined as a constant. At the same time, the nozzle should be prevented from loosening and the support of "water replenishing device" in the condenser should be considered.
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