JPS6142390A - Method for making pure water for boiler - Google Patents

Abstract

PURPOSE:To make high purity water for a boiler at low cost, by supplying distilled water, which was passed through an ion exchanger, to a boiler and driving turbine by steam generated by the boiler while condensing the exhaust gas of the turbine by a condenser. CONSTITUTION:Seawater with temp. of about 20 deg.C is heated to about 30 deg.C by the waste heat of a turbine condenser while pumped up and the greater part thereof is discarded from a pipe 3 while the remainder is flowed into a three- fluid heat exchanger 5 through a pipe 4 to be heated to about 60 deg.C and reaches a steam compression type evaporator 9 through a pipe 8. The seawater preheated to about 60 deg.C is scattered on a horizontal heat transfer tube bundle 10 from a scattering apparatus 11 and evaporated through the heat exchange with the high temp. fluid in the tube bundle 10 while the generated steam is compressed by a compressor 14 and introduced into the tubes of the horizontal heat transfer tube bundle 10 at high temp. to be converted to a heating source and, after condensed by heat exchange, the condensate is flowed out to an outlet side header 17 to enter the three-fluid heat exchanger 5 at about 70 deg.C. Conc. seawater enters the three-fluid heat exchanger 5 at about 60 deg.C from a conc. seawater sump 19.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing feed water for a high pressure boiler operating at supercritical pressure.

(Conventional technology) Turbines that use supercritical pressure steam undergo salt reduction and depressurization each time they perform work at each stage, and if salts are present in the stem air, these will reduce the age of the smelt. It deposits on the nozzles and W of each stage, causing steam flow resistance and vibration, and affecting turbine efficiency. Therefore, mixing of salts into the steam must be avoided as much as possible.

The quality of the steam generated in the boiler is greatly influenced by the properties of the feed water once it reaches critical pressure. In other words, impurities in the feed water are divided into two types: salts such as gold Iri mixed into the steam, and scale deposited on the boiler pipe walls, both of which impede the turbine. High purity is required, with the amount of dissolved ions being 0.2 PPM or less.

In order to satisfy such severe conditions, conventionally, tap water is passed through an ion exchanger to reduce the amount of dissolved ions to 0.
It was reduced to 2 ppm, but tap water usually has a concentration of 1100.
The amount of impurities is large, and the removal of these impurities requires the use of a large amount of ion exchange resin, making the equipment large and requiring a large amount of chemicals for regeneration. Improvements have been desired due to the high cost of sewage treatment of the wastewater produced during the process.

Instead of tap water, there is a method of using distilled water that can be obtained from a normal desalination multi-stage flash evaporator, a multi-effect evaporator, etc. that uses salt water such as seawater as raw water. This distilled water has about 2 ppm of impurities, which is only about 1,150 impurities compared to the tap water mentioned in -1-, and the ion exchangers of I&Z have also become smaller and use ion exchange resin. It is economical because the amount is reduced and the processing cost is reduced in proportion to the amount of ions, but its economic efficiency should have been pursued further through technological development.

(Problem to be solved by the invention) Therefore, we focused on the fact that if this distilled water could be produced with lower energy consumption, the cost of high-purity water for boiler water supply could be further reduced, and the present invention aimed to improve the economic effect. It is.

When seawater is desalinated by normal multi-stage flashing and multi-effect evaporation to provide high-purity boiler feed water, the energy consumption for desalination is approximately 70,0OOKcal/t and the price is approximately 400 yen/l, which is equivalent to It has a high price.

On the other hand, the air compression method, which is a type of evaporation method, adiabatically compresses the stem air generated in the evaporator and reuses it as heated steam in the evaporator to produce water. It is a desalination method with high thermal efficiency, with only a fraction of the heat of vaporization (latent heat). It is heated by the heat source from the start time section, and when it reaches a predetermined temperature, the compressor is used as the heat source to heat the evaporated salt rff at the temperature T2 after compression and compression 111].
Bookbinding is performed in one heat exchange with the temperature difference T2-TI.
This is an evaporation method that consumes little energy and operates by simply adding a small amount of auxiliary heat from the outside to maintain the generator at a predetermined temperature.

The present invention focuses on this air compression method with high thermal efficiency, and the gist of the present invention is that if the distilled water obtained by this method is used as a raw material for boiler feed water, it is possible to produce boiler feed water with higher economic efficiency.

(Means for solving the problem) When producing 1 ton of distilled water from seawater using the fuji compression method,
“Approximately 8KWII is required for compressor power.The amount of heat equivalent to this power is 8KWII x 860Kcal/
KWH=6880Kcal, but since this amount of heat alone cannot maintain the evaporator at a predetermined temperature, it is necessary to introduce about 16.0OOKcal from the outside as auxiliary heat, and turbine extraction air is used for this purpose. On the other hand, compared to using cold seawater as raw water, using heated wastewater from the turbine condenser as raw water can save about 4,000 Kcal of auxiliary heat for maintaining the evaporator at a predetermined temperature.

If we consider the power generation efficiency of 8KWl+ of compressor power as 30%, we can simply calculate the total amount of heat used: Heat equivalent to compressor power −−−−−−−−23,0OOKc
a l auxiliary heat ------------------------16,
000Kca I Fuku JL cane stem J roof 4 section j2! Ripe------
−−−−−1−−−−−・−J River (1↓Total amount of heat used
It becomes 35,000Kcal,
Heat consumption due to conventional multi-stage flash and multi-effect evaporation 7
It can be reduced by half compared to 0.000Kcal.

Of course, raw water other than seawater can be widely used, such as river water, groundwater, and saltwater such as factory wastewater.

- In view of the above, the present invention supplies a part of the turbine condenser cooling wastewater to a vapor compression type evaporator to evaporate it, compresses and condenses this vapor to form condensed water, and converts the distilled water into an ion exchanger. A boiler feed water production method in which water is then supplied to the boiler, the steam generated in the boiler drives a turbine, and the turbine exhaust is condensed in the condenser, and the turbine extracted air is guided to the evaporator to reduce the evaporation temperature. This provides a method for producing boiler feedwater as an auxiliary heat source for maintenance.

(Function) According to this method, the energy consumption of the water entering the ion exchanger can be reduced to nearly half that of distilled water obtained by ordinary multi-stage flash and multi-effect evaporation methods, and the unit cost of water treatment is reduced. becomes lower. This is because the waste heat of the turbine condenser is used to preheat the raw water, so less energy is required to maintain the evaporation temperature, which combines with the thermal economy of the vapor compression evaporation method to further reduce energy consumption. (Example) The figure is a flow sheet showing an example of the present invention, and description will be made with reference to this figure.

Seawater at about 20°C pumped up from pipe 1 rises in temperature to about 30°C due to the exhaust heat from turbine condenser 2, and then most of it wanders out from pipe 3, and some passes through pipe 4 and is converted to fluid heat. It flows into exchanger 5. This ball fluid heat exchanger 5 has a condensate water pipe bundle 6
and a concentrated seawater tube bundle 7, and the outside of the tube bundle has a structure through which the seawater flows, and the seawater is heated to about 60° C.
It passes through and reaches the stem air compression type generator 9.

This vapor compression type evaporator 9 has a horizontal heat exchanger tube bundle IO in a container, and a dispersion device 11 is disposed on the L side of the horizontal heat exchanger tube bundle IO.
0 outside the pipe (Il + space 12 is steam inlet pipe 13, compressor 1
4. It is connected to the inlet header 16 of the horizontal heat transfer tube bundle via the steam outlet pipe 15. The outlet willow 1 header 17 of the horizontal heat transfer tube bundle has a condensate reservoir 18.1 at the bottom! : The lower part of the container is at the concentrated seawater level 19, and a vacuum pump 20 is connected to the outlet header 17 to maintain the evaporator 9 in a vacuum.

As mentioned above, seawater preheated to 4V to about 60°C is (K
Spreading from the heavy equipment W I 1 to the horizontal heat exchanger tube bundle 101-,
The steam is emitted by exchanging heat with the high-temperature fluid inside the pipes, and the generated steam is compressed in the condenser 14, and the heated steam is introduced into the pipes of the horizontal heat transfer tube bundle and becomes a heating source, and after heat exchange, it condenses. It flows out to the outlet side header 17, collects in the condensate reservoir 1B, and pumps 2.
1 and enters the fluid heat exchanger 5 at about 70°C.

The concentrated seawater enters the ball fluid heat exchanger 5 at about 68° C. from the lower concentrated seawater level 19 by the pump 22.

The condensed water cooled to about 40°C in the ball fluid heat exchanger 5 passes through the pipe 23 and enters the ion exchanger 24, where impurities are removed and the water has a high purity of about 0.2 ppm. It is mixed with water and supplied to the boiler 26 via the pump 25. The cow steam from the boiler is supplied to the turbine 27 to drive the generator 28, and the turbine extracted air is supplied to the temperature controller 31.
It enters the large RL side header 16 through a certain pipe 30, and serves as an auxiliary heat source to maintain a predetermined heating temperature. The turbine exhaust gas is condensed in condenser 2 by exchanging heat with cold seawater. 29 is a combustion device.

(Effects) In the present invention, a part of the turbine condenser cooling waste water is supplied to a vapor compression type evaporator and evaporated, this vapor is compressed and condensed to produce distilled water, and the distilled water is passed through an ion exchanger. This is a boiler water supply method in which water is then supplied to the boiler, the steam generated by the boiler drives the turbine, and the turbine exhaust is condensed by the condenser.
The feed water that enters the ion exchanger can take advantage of the advantage that the work of the compressor of the vapor compression evaporation method is only a fraction of the heat of vaporization (latent heat), and furthermore, it can be applied to the cooling seawater by the turbine condenser. The generated heat is used to maintain the evaporator at a predetermined temperature, so compared to distilled water obtained from conventional multi-stage flash and multi-effect evaporation methods, the energy required is approximately half, making it possible to produce high-purity water for boilers. This has an economical effect of lowering the cost of water treatment.

[Brief explanation of drawings]

The figure is a flow sheet in one embodiment of the present invention. 2... Condenser, 5...: Fluid heat exchanger, 9
... Vapor compression evaporator, 10... Horizontal heat transfer tube bundle, 11... Spreading device, 14
...Compressor, 24...Ion exchanger, 26
...Boiler, 27...Turbine, 28.
··Generator.

Claims (2)

[Claims] (1) A portion of the turbine condenser cooling wastewater is supplied to a vapor compression evaporator and evaporated, this vapor is compressed and condensed to produce distilled water, and the distilled water is passed through an ion exchanger and then supplied to the boiler. A boiler feedwater production method in which a turbine is driven by steam generated in the boiler, and turbine exhaust gas is condensed in the condenser. (2) In the method for producing boiler feed water according to item 1, turbine bleed air is guided to the evaporator and used as an auxiliary heat source for maintaining the evaporation temperature.