JPS59137786A - Air extractor for condenser - Google Patents

Abstract

PURPOSE:To enable to optimally operate an air extractor, by a method wherein the pressure in the first-stage condenser is maintained to be constant by controlling the flow rate of cooling water, and the number of ejectors operated is controlled by detecting the temperature of a gas at inlets of the ejectors. CONSTITUTION:Bleed air [arrow (a)] from the condenser in a steam turbine system is raised in pressure by steam fed from a steam source [arrow (b)] at the first ejectors 1a, 1b, and is cooled by cooling water in the first-stage condenser 3. Cooling water in the condenser 3 is controlled by the first-stage flow control valve 14 so that the temperature of water discharged from the condenser 3 is maintained to be constant. Namely, by maintaining the pressure (saturated pressure) in the condenser 3 to be constant, the performance of the ejectors can be maintained in an optimum condition. In addition, since the ratio of air to steam can be easily calculated from the pressure in the condenser and the temperature of bleed air on the basis of the characteristics of air and steam, extracting capacity of the ejectors can be gradually controlled by selecting a combination of the first-stage ejectros 1a, 1b.

Description

[Detailed description of the invention] This relates to an air extraction device for a condenser.

First, an overview of the conventional example will be described.

Conventionally, a two-stage steam injection air ejector with a surface condenser shown in FIG. 1 and a water ring rotary vacuum pump shown in FIG. 2 have been employed as air extraction devices for condensers.

In FIG. 1, 01 is the first stage ejector, 02 is the second stage ejector, 03 is the first stage supply condenser, 04 is the second stage condenser, arrow a is from the condenser, arrow b is from the steam source, Arrow C shows the flow of condensate from the condensate pump, arrow d shows the flow to the atmosphere, and arrow e shows the flow to the low pressure heater.

The two-stage steam injection air ejector with surface condenser shown in Figure 1 does not have any control device installed in the first stage condenser 03, and the ejector can be operated at the design point without any control. If this is not possible, the operation will be low in efficiency, and if the conditions are bad, the ejector will become inoperable.

In FIG. 2, reference numeral 05 is an air-driven ejector, 06 is a water ring vacuum pump, arrow a indicates flow from the condenser, and arrow d indicates flow to the atmosphere.

In the case of the water ring rotary vacuum pump shown in Figure 2, the ejector driving medium is air, so unlike the above-mentioned air ejector with a surface condenser, the ejector does not become inoperable, but if the driving medium is air. In addition, the water ring type pump corresponding to the second stage ejector is
No. 6 requires extracting the driving air of the first stage ejector, further deteriorating the efficiency.

There are two types of air extraction devices for condensers, each of which has the drawbacks mentioned above, but some say that the steam injection ejector is more efficient and lower in cost. For some reason, water ring type vacuum pumps tend to be adopted more often, and while we were investigating the causes and countermeasures for this, the present invention was developed in an attempt to eliminate the above drawbacks.The new features are as follows: a. ), to take advantage of the characteristics of the ejector (single point design),
The internal pressure of the first stage condenser is maintained constant by controlling the flow rate of cooling water.

b) The ejector inlet gas temperature is detected and the number of operating ejectors at each stage is controlled so as to optimize the ratio of air to steam in the ejector inlet gas.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

(3) In FIG. 3 showing the system of the air extractor of the present invention, reference numerals 1a and 1b refer to first stage steam injection ejectors (hereinafter referred to as first stage steam injection ejectors).
2a and 2b are second stage steam injection ejectors (hereinafter referred to as second stage ejectors), 3 is a first stage soap condenser (hereinafter referred to as first stage condenser), and 4 is a second stage Direct shaft condenser (hereinafter referred to as second stage condenser), sa and sb are first stage ejector inlet check valves (hereinafter referred to as first stage check valves), 6 is an ejector drive steam pressure control valve (hereinafter referred to as ejector 7 is an ejector-driven steam pressure transmitter (hereinafter referred to as ejector transmitter),
8 is an ejector drive steam pressure regulator (hereinafter referred to as an ejector regulator), 9 is a first stage ejector inlet air temperature switch (hereinafter referred to as a first stage temperature switch), 10a, and Job is a first stage ejector drive steam opening/closing control valve ( Hereinafter, 1st stage control valve),
ha, 11b is the second stage ejector artificial check valve (hereinafter referred to as the second stage
12 is the second stage ejector inlet air temperature switch (hereinafter referred to as the second stage temperature switch), 13a and 1.3b are the second stage ejector drive steam opening/closing control valves (hereinafter referred to as the second stage check valve section). 14 is a first stage condenser cooling water flow control valve (hereinafter referred to as
15 is a 1st stage transmitter outlet condensate temperature transmitter (hereinafter referred to as 1st stage transmitter); 16 is a 1st stage transmitter outlet condensate temperature regulator (hereinafter referred to as (abbreviated as 1st stage temperature controller), arrow a indicates the flow from the condenser, arrow s indicates the flow from the steam source, arrow d indicates the flow to the atmosphere, arrow e indicates the flow to the exhaust heat recovery system, and arrow f indicates the flow from the cooling water source. It shows.

Extracted air from the condenser of the steam turbine system passes through the first stage check valves 5a and 5b, and then passes through the first stage ejector 1a or 1b.
The pressure is increased and sent to the first stage condenser 3.

1st stage ejector, ta, 1b, ejector pressure control valve 6
It is driven by steam from a steam source (arrow b) such as a boiler whose pressure is adjusted to a constant level.

The first stage ejectors 1a, xb are operated and stopped by supplying or cutting off driving steam using the first stage control valves 10a, 10b. When the ejector is stopped, the first stage check valve 5
a and 5b prevent backflow from the first stage condenser 3.

The extracted air pressurized by the first stage ejector 1a or 1b and the steam that drove the ejector enter from the lower part of the first stage condenser 3, and are cooled by cooling water falling from the upper part of the condenser, and most of the steam is becomes water and becomes the cooling water of the second stage condenser 4 together with the cooling water that has completed heat exchange. The extracted air and some steam are discharged from the top of the first stage condenser 3 and directed to the second stage ejector 4.

The cooling water in the first stage condenser 3 is pumped up condensate from the steam turbine system condenser, and the first stage flow control valve 14
, and is supplied from the upper part of the first stage condenser 3. The first stage flow rate control valve 14 is controlled to maintain the temperature of the waste water of the first stage condenser 3 constant. That is, the first stage condenser 3
Maintain the internal pressure (saturation pressure) constant.

Extracted air discharged from the first stage condenser 3 is pressurized to atmospheric pressure by the second stage ejectors 2a, 2b as in the first stage, and enters the second stage condenser 4.

Cooling water from the cooling water 3 of the first stage condenser 3j passes through a siphon (to prevent backflow) and is supplied from the upper part of the second stage condenser 4, cooling the exhaust gas of the second stage ejectors 2a and 2b.
It is discharged from the lower part of the second stage condenser 4 and supplied to the exhaust heat recovery device.

The extracted air is sent to the atmosphere from the top of the second stage condenser 4 (arrow d)
released.

Next, the effects of the air extraction device according to the present invention will be described.

The ejector is a typical single point design device. That is, the designed suction capacity is obtained only when all conditions of suction pressure, discharge pressure, and driving steam pressure are at the designed values, but when the above conditions are deviated from, the performance is significantly reduced. In particular, an increase in discharge pressure and a decrease in driving steam pressure cause malfunction. The present invention takes into full consideration the characteristics of the ejector described above. That is, a) the performance of the ejector can be optimized by keeping the internal pressure of the first stage condenser 3 constant, the temperature of the cooling water drainage, and the flow rate of the cooling water.

b) In order to keep the air content in the condensate of the condenser below the target value, an air extraction device usually extracts steam from 2 to 7 times the amount of extracted air together with the extracted air. The ratio of air and steam can be easily calculated from the (7) characteristics of air and steam, the internal pressure of the condenser, and the temperature of the extracted gas (air and steam).

In the present invention, paying attention to this point, the number of operating ejectors at each stage is controlled depending on the ejector inlet temperature, so that the air extraction device can be operated optimally. That is, in the example shown in FIG. 3, there are two first-stage ejectors 1a and 1bfd, and if the capacity of ejector 1a is 1, then ejector 1b
The extraction capacity of the ejector is designed to be 2, and by selecting the number of operating ejectors i1a, 1b, and 1a+lb, the extraction capacity of the ejector can be controlled stepwise to 1.2 and 3.

In the case of this embodiment, there are two ejectors, but if three ejectors are used, detailed control of 1, 2, 3, 4, 56 and 7 will be possible using the same method.

[Brief explanation of drawings]

Figures 1 and 2 are conventional air extraction equipment, Figure 1 is a system diagram of a two-stage steam injection air ejector with a surface condenser, Figure 2 is a system diagram of a water ring rotary vacuum pump, and Figure 3 is a system diagram of a water ring rotary vacuum pump. is a system diagram (8) of the air extraction device of the present invention. 1a11b... 1st stage ejector, 2a12b... 2nd stage ejector, 3... 1st stage condenser, 4... 2nd stage condenser,
5a, sb...1st stage check valve, 6...Ejector pressure control valve, 7...Ejector transmitter, 8...Ejector regulator, 9
...1st stage temperature switch, 10a, 10b...1st stage control valve, il a, ]1b --2nd stage check valve, 12...
2nd stage temperature switch, 13a, 13b...2nd stage check valve mode valve, 14...1st stage check valve mode valve, 15...1st stage transmitter, 16...1st stage temperature controller . Figure 1 Figure Z Figure 3 Figure m-(

Claims (1)

[Claims] In the air extraction device, the internal pressure of the condenser is kept constant,
In order to achieve high efficiency of the device, a condenser cooling water flow control valve is installed on the upstream side of the condenser to fully control the condenser cooling water flow rate, and a condenser cooling water flow control valve is installed on the upstream side of the ejector to control the ratio of air to steam in the ejector inlet gas. An air extraction device for a condenser, characterized in that it is equipped with a temperature switch that controls the temperature to an optimum value, and a control valve that supplies and cuts off driving steam and controls the number of ejectors in operation at each stage.