JPH1047015A - Generation and sea water desalting combined device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a generation and sea water desalting combined device to ensure a constant generating amount regardless of a fluctuation in a fresh water amount and provide high integral heat energy efficiency for generation and fresh water generation, and high economical efficiency. SOLUTION: A generation and sea water desalting combined device comprises a circulation fluidized bed boiler 16 to generate superheated steam by burning fuel, such as RDF; a back pressure bleed steam turbine 18 to introduce steam from a boiler and convert it into a power to drive a generator 17; a multiple effect vaporizing can device 34 to desalt sea water by means of back pressure steam of a turbine serving as a heat source; an auxiliary condenser 22 to condense surplus back pressure steam; and deaerator 28 to deaerate condensate from a vaporizing can device for a multiple effect and condensate from a condenser by middle pressure steam bled and feed it to a boiler. This constitution realizes a system having extremely high thermal efficiency. Further, thermal power generating equipment is provided with an auxiliary condenser to condense surplus back pressure steam flowing out from a back pressure steam turbine, whereby generation by a constant output is practicable regardless of a fluctuation in a fresh water amount of a sea water desalting device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined power generation and seawater desalination apparatus, and more particularly, to a high overall thermal efficiency of power generation and seawater desalination, and a constant electric power regardless of fluctuations in fresh water production. Combined power generation and seawater desalination using a circulating fluidized bed boiler using solid fuel or solid industrial waste obtained from combustible waste as fuel It concerns the device.

[0002]

2. Description of the Related Art In areas where water resources are scarce, such as remote islands, and are isolated from other areas, it is very important to secure fresh water such as drinking water. In recent years, seawater desalination, in which electric power is supplied from a power company and freshwater is obtained from seawater using a reverse osmosis membrane, is frequently used. In principle, seawater desalination involves either evaporating seawater to remove freshwater or removing dissolved salts from seawater, and there are two main types: evaporation and membrane. .

[0003] In the evaporation method, seawater is heated to produce steam,
This method is a method of obtaining fresh water by cooling, and consumes a large amount of heat energy, which is not economical. The other membrane method includes two methods, a reverse osmosis method and an electrodialysis method. The reverse osmosis method (RO method) is a method in which fresh water is obtained from seawater by applying a pressure higher than the osmotic pressure to the seawater side, using a semipermeable membrane having a property of allowing water to pass through, but hardly allowing salt to pass. Therefore, in seawater desalination by the RO method, 25 kg / cm ²
As described above, practically, it is necessary to increase the pressure to a pressure in the range of 50 to 60 kg / cm ² , and there is a problem that the power cost increases.
In addition, in the electrodialysis method, seawater is passed between a cation exchange membrane selectively passing cations and an anion exchange membrane selectively passing anions, and a DC voltage is applied to both ends of the ion exchange membrane.
In this method, ions in seawater are moved through a membrane to desalinate. This method requires two types of ion exchange membranes,
Desalination of seawater with a high salt concentration has a problem that equipment costs increase.

[0004] Therefore, an attempt has been made to install a thermal power generation facility and desalinate seawater by an evaporation method using waste heat generated from the thermal power generation facility, and to reduce the power generated from the thermal power generation facility. Attempts have been made to desalinate seawater using the reverse osmosis method.

[0005]

However, in a conventional dual purpose power generation and seawater desalination combined apparatus for simultaneously obtaining electric power and freshwater by an evaporation method, a steam for driving a generator is used as a heating source of the seawater desalination apparatus. Because it uses high-level turbine bleed steam from the turbine,
The amount of power generated by the thermal power plant decreases accordingly, and the amount of generated power and the amount of fresh water produced by seawater desalination are always constant, and the amount of freshwater produced by the seawater desalination equipment without changing the amount of power generation is free. Could not be set to. In addition, the combined use of a condensate turbine condenser (condenser) as part of the power generation equipment using a bleed condensate steam turbine separately from the seawater desalination equipment, Although it is possible to adjust the amount of fresh water, there is a problem that the amount of generated power changes as the amount of fresh water changes. Also,
Conventional power generation using seawater desalination equipment by reverse osmosis
In the seawater desalination combined device, it has been difficult to solve the problem that the equipment cost and the operation cost increase.

Accordingly, an object of the present invention is to provide a power generation and seawater freshwater which can secure a fixed amount of power generation irrespective of fluctuations in the amount of fresh water, have high overall thermal energy efficiency in power generation and fresh water, and have high economic efficiency. To provide a chemical combined device.

[0007]

Means for Solving the Problems The present inventor has repeatedly studied from various aspects, and as in the prior art, has developed a medium pressure steam supplied from a thermal power plant, for example, about 3 kg / cm ² g. As long as seawater is desalinated by evaporation using pressure steam,
It was concluded that it was difficult to improve the overall thermal energy efficiency of power generation and desalination from the conventional level. Then, the thermal energy of the steam generated by the boiler of the thermal power plant is used as much as possible for power generation, collected as electrical energy, and the multi-effect evaporation is performed using the heat of the low-pressure steam, which has a low pressure and economic value. Focusing on seawater desalination using a seawater desalination apparatus, a large number of process simulations were performed to find the pressure range of low-pressure steam with the highest thermal efficiency, and the present invention was completed.

In order to achieve the above object, a combined power generation and seawater desalination apparatus according to the present invention comprises a boiler for generating steam, a generator rotated by the steam generated by the boiler, and a generator for generating power. A thermal power plant having a back-pressure steam turbine for generating 25-0.5 kg / cm ² abs of back-pressure steam, a steam room, a condenser and a seawater sprinkler for sprinkling seawater into the condenser are respectively provided in the steam room. A plurality of evaporators having a steam chamber of one evaporator and a condenser of the next-stage evaporator in communication with each other, and a seawater desalination facility comprising a connected multi-effect evaporator device, The back-pressure steam from the high-pressure steam turbine is introduced into the condenser of the first-stage evaporator of the seawater desalination facility, and the heat of the steam condensed in the condenser evaporates the seawater sprinkled from the seawater sprinkler in the steam chamber and evaporates. The steam is condensed in the next evaporator. Into the vessel, and sequentially generate steam in the steam chamber to serve as a heat source for evaporating the seawater and collect the condensed water obtained by condensing the steam evaporated from the seawater with the condenser and send it as fresh water, Condensed water of back-pressure steam condensed in the first-stage evaporator is recovered and supplied to the boiler as boiler water.

The mode of introducing seawater into each evaporator of the multi-effect evaporator apparatus is not particularly limited, but preferably, a preheater is provided in a steam chamber of a part of the evaporator, and seawater is heated by the heat of the steam chamber. When preheating is performed, thermal efficiency is improved. Further, the pressure in the evaporator becomes a saturation pressure corresponding to the evaporating temperature of seawater in each can, and gradually decreases from the first-stage evaporator to the last-stage evaporator. Therefore, the evaporation temperature of the seawater in the evaporator gradually decreases from the first evaporator to the last evaporator according to the pressure of each steam chamber. The bottom of each evaporator communicates with the bottom of the next evaporator via piping, and the concentrated seawater in the evaporator sequentially flows into the next evaporator via the pipe due to the pressure difference, and ends. It is discharged out of the system from the stage evaporator.

In a preferred embodiment of the present invention, an auxiliary condenser for condensing surplus back-pressure steam from the back-pressure steam discharged from the back-pressure steam turbine when desalination of the seawater desalination equipment is reduced is provided in the thermal power generation equipment. By condensing excess backpressure steam other than the backpressure steam supplied to the seawater desalination facility, the thermal power generation facility can be operated at a predetermined output regardless of the amount of desalination of the seawater desalination facility. Can be. When the amount of fresh water produced by the multi-effect evaporator type seawater desalination device is insufficient, in addition to the multi-effect evaporator device, a reverse osmosis membrane is used to convert the permeated water with a low salt concentration and the salt water with a high salt concentration. The reverse osmosis membrane device to be separated may be provided in the seawater desalination facility, and the power required for operating the reverse osmosis membrane device may be supplied from the thermal power generation facility.

A further preferred embodiment of the present invention is characterized in that the boiler of the thermal power plant is a circulating fluidized bed boiler using solid fuel or solid industrial waste as fuel for combustible waste. And In the present embodiment, a solidified fuel production device is provided, and combustible waste, for example, solidified fuel (RDF) obtained by processing combustible waste with the solidified fuel production device is burned in a circulating fluidized bed boiler. Thereby, garbage disposal, power generation, and fresh water generation can be performed simultaneously. RDF is a generic name for solidified fuels obtained by subjecting combustible wastes to processing such as sorting, pulverization, particle size adjustment, and solidification. Preferably, an RDF in the form of a pellet that has been molded and solidified is used. A circulating fluidized bed boiler is a boiler that burns RDF in a circulating fluidized bed, and usually includes a dust collector such as a cyclone that collects dust. In a preferred embodiment of the present invention, a back-pressure steam turbine for extracting medium-pressure steam used as deaeration steam for boiler feedwater is provided as the back-pressure steam turbine. This eliminates the need to separately generate degassing steam.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. This embodiment is an embodiment of the combined power generation and seawater desalination apparatus according to the present invention, and includes a thermal power plant using solidified fuel as fuel, and a seawater desalination by a multiple effect evaporator method and a reverse osmosis membrane method. This is an example of a combination with a chemical facility. 1 and 2
Are flow sheets each showing the configuration of the present example. Power generation / seawater desalination combined device 10 of the present embodiment
(Hereinafter referred to as the apparatus 10) is an apparatus combining the thermal power generation equipment 12 shown in FIG. 1 and the seawater desalination equipment 14 shown in FIG.

[0013] The thermal power generation equipment 12 is provided with
Circulating fluidized bed boiler (RDF)
uidized-Bed Combustor, CFB boiler) 16 (hereinafter,
The power is obtained by the superheated steam generated from the boiler 16, the generator 17 is rotated, and two types of medium-pressure steam having different pressure levels, namely, 10 kg
/ cm ² g and 3 kg / cm ² g of steam are extracted, and 0.3 kg / c
back-pressure bleeding steam turbine 18 that generates m ² abs back-pressure steam
And Further, the thermal power generation equipment 12 sends all or a part of the back pressure steam to the seawater desalination equipment 14, and the piping systems 20, 21, and 10 receive the condensed water condensed there.
kg / cm ² g extraction steam is supplied to a seawater supply line degassing ejector by a piping line 51, an auxiliary condenser 22 for condensing excess backpressure steam, and a seawater desalination facility 14 via a piping system 21. A condensed water receiving tank 24 is provided for receiving the condensed condensed water and the condensed water condensed by the auxiliary condenser 22.
The thermal power generation equipment 12 includes, as a boiler water supply system, an ion-exchange type pure water apparatus 26 for purifying condensed water collected in a condensed water receiving tank 24 and a deaerator 28 for removing gas components in the condensed water.
And a condensed water pump 30 for supplying condensed water in the condensed water receiving tank 24 to the deaerator 28 via the pure water device 26, and a boiler water pump 32 for supplying water from the deaerator 28 to the boiler 16.

The seawater desalination facility 14 comprises a multiple effect evaporator unit 34 and a reverse osmosis membrane unit 36. The multiple effect evaporator unit 34 includes a plurality of (in FIG. 2, N evaporators are shown) evaporators 38 </ b> A to 38 </ b> N, a seawater pump 40 that supplies seawater to the seawater desalination facility 14, and a seawater pump 40. A steam ejector for removing gas components in the seawater supply system supplied by the pump; Each evaporator 38 is formed of a can body having a steam chamber therein, and includes at least a condenser 44 and a seawater sprinkler 46 for sprinkling seawater into the condenser 44 in the steam chamber. , A seawater preheater 48. The temperature and pressure in the vapor chamber of the evaporator are set so as to decrease from the first-stage evaporator to the last-stage evaporator. In this embodiment, the first-stage evaporator has a pressure of 0.22 kg / cm ² abs. , And the last stage evaporator is 0.0
It is set to 66 kg / cm ² abs. The vapor chamber of each evaporator 38 communicates with the condenser 44 of the next evaporator,
The steam generated in the steam chamber flows into the condenser 44 of the next stage evaporator, where it is condensed. In addition, the bottom of each evaporator communicates with the bottom of the next evaporator via piping, and seawater that has not evaporated in each evaporator flows into the next evaporator due to the pressure difference. It flash evaporates partially and is finally discharged outside the facility as concentrated seawater.

More specifically, in the first stage evaporator 38A,
The back pressure steam supplied from the thermal power plant 12 is
A, the condensed water is condensed in a condensed water receiving tank 24 by a piping system 21.
to go into. On the other hand, part of the seawater sprinkled from the seawater sprinkler 46A evaporates due to the heat of condensation of the back-pressure steam, and enters the condenser 44B of the second-stage evaporator 38B. Also, the first stage evaporator 38A
The seawater that did not evaporate in the second stage evaporator 38B enters the can of the second stage evaporator 38B due to the pressure difference between the first stage evaporator 38A and the second stage evaporator 38B, and partially flash evaporates. Second stage evaporator 38B
Then, the vapor evaporated in the first-stage evaporator 38A is transferred to the condenser 44B.
And enters the condensed water collecting pipe 50. On the other hand, part of the seawater sprinkled from the seawater sprinkler 46B evaporates due to the heat of condensation of the steam condensed in the condenser 44B, and the third-stage evaporator 38C
Into the condenser 44C. Further, the seawater not evaporated in the second-stage evaporator 38B is mixed with seawater from the first-stage evaporator 38A due to a pressure difference from the third-stage evaporator 38C.
Enter C and flash evaporate partially.

In the N-1st stage evaporator 38N-1 and the last stage evaporator 38N, as described above, inflow of steam, sprinkling of seawater, condensation of steam, evaporation of seawater, and movement due to seawater pressure difference occur. . In the final stage evaporator 38N, the receiving plate 5 receives the condensed water of the steam generated by the preheating of the seawater in the preheater 48.
The condensed water received by the receiving plate 52 is collected in the condensed water collecting pipe 50.

The reverse osmosis membrane device 36 includes a seawater filtration device 54 for capturing foreign substances, a reverse osmosis membrane 56, and a pressurizing pump (not shown) for pressurizing and supplying seawater to the reverse osmosis membrane 56.
It is equipped with necessary facilities such as.

The boiler 16 has an RDF as shown in FIG.
Hopper 60 containing RP, RD supplied from hopper 60
A furnace 62 for circulating and burning F in a fluidized bed to generate steam in a water pipe (not shown); a steam drum 64 connected to the water pipe to allow steam multi-phase water to flow therein to separate gas and liquid; An evaporating tube group 66 for circulating water between the water drum 80 and evaporating it as water vapor is provided. Further, the boiler 16 is provided in the flue 70 for collecting and collecting a large amount of dust generated by the combustion of the RDF from the flue gas, and the flue 70 for flowing the flue gas. A superheater 72 that superheats the steam emitted by the flue gas, an air preheater 76 that preheats the combustion air with the flue gas, and a blower 78 that blows the combustion air are provided. If necessary, an economizer for preheating boiler water supplied to the steam drum 64 with flue gas may be provided. The ash is collected from the flue 70 and the bottom of the furnace 62. In addition, the device 1
0 includes a condensed water pump 30, a boiler water pump 32, a seawater pump 40, and the like, as well as a pump as necessary as shown in the flow sheets of FIGS.

In the apparatus 10, as shown in FIG. 4, superheated steam is generated by the boiler 16 of the thermal power generation equipment 12, and the superheated steam is sent to the back pressure extraction steam turbine 18, and the generator 17
Is rotated to generate electric power, and the medium-pressure steam is extracted and supplied to the deaerator 28 as deaeration steam. 0.3kg / cm ² abs
All or part of the back pressure steam is sent to the multiple effect evaporator unit 34 of the seawater desalination facility 14 by the piping system 20 to collect the fresh water from the sea water by the evaporation method and to condense the water obtained by condensing the back pressure steam. The gas is returned to the thermal power generation facility 12 via the deaerator 28 by the piping system 21. Therefore, the multiple effect evaporator unit 34 constitutes a part of the condenser of the back pressure bleed steam turbine 18. When the amount of fresh water produced by the multi-effect evaporator 34 is insufficient, the reverse osmosis membrane device 36 is operated using the electric power generated by the thermal power plant 12, and the permeated water, that is, fresh water, is obtained from seawater by the reverse osmosis method. Can be. Apparatus 10 of the present embodiment
Since the auxiliary condenser 22 is provided, the thermal power generation equipment 12 can be operated at a predetermined output regardless of a change in the amount of fresh water of the multiple effect evaporator unit 34.

In order to evaluate the apparatus 10, the amount of fresh water is 5
The process simulation was performed on the assumption that the fresh water ratio was 10 at 00 Ton / Day, and the following results were obtained. The main operating conditions of the apparatus 10 when performing the process simulation are as follows. The pressure of the superheated steam: 32kg / cm ² g superheated steam temperature: 420 ° C extraction backpressure steam turbine back pressure: 0.3kg / cm ² abs degassed dexterity extraction steam pressure: 3kg / cm ² g seawater deaerator Pressure of extracted steam for use: 10 kg / cm ² g Supply temperature of boiler water: 100 ° C RDF lower heating value (LHV): 4,300 Kcal / Kg Boiler efficiency: 80% Steam chamber pressure of first stage evaporator: 0.22 kg / cm ² abs Steam chamber pressure of final stage evaporator: 0.066 kg / cm ² abs Seawater temperature: 30 ° C

The results of the above process simulation are as shown in Table 1.

[Table 1] As is clear from Table 1, the overall thermal efficiency of the combined power generation and seawater desalination apparatus is about 26% in the flow sheet of FIG. 4, and the thermal efficiency of the apparatus 10 is lower than that of the conventional waste combustion type power generation apparatus. Is extremely high. This difference is due to seawater desalination using steam of low economic value. It should be noted that the stream numbers in Table 1 are shown in FIGS.
In the right place.

[0022]

According to the configuration of the present invention, the steam turbine is driven by the thermal power generation equipment to generate electric power, and at the same time, the ultra low temperature and low pressure waste steam (0.
Fresh water is obtained using a multi-effect evaporator-type seawater desalination apparatus using 3 kg / cm ² abs of steam as a heat source. In addition, seawater desalination equipment plays the role of a condenser by recovering ultra-low-temperature, low-pressure steam that has heated seawater as condensate and then circulating it as boiler feedwater, realizing a system with extremely high thermal efficiency. I have. Further, since the thermal power generation equipment is provided with a condenser for excess back pressure steam from the back pressure steam turbine, it is possible to generate power at a constant output regardless of a change in the amount of fresh water generated by the seawater desalination apparatus. In other words, the amount of fresh water and the amount of power generation can be freely combined. Furthermore, since the evaporation temperature of the seawater of the seawater desalination apparatus is as low as 62 ° C. or less, there is little problem of corrosion and scaling of equipment and piping. Further, by combusting combustible waste, for example, solidified fuel (RDF) obtained by processing waste in a circulating fluidized-bed boiler, waste treatment, power generation, and seawater desalination can be efficiently performed simultaneously.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a configuration of a thermal power generation facility of a combined power generation / seawater desalination apparatus according to the present invention.

FIG. 2 is a flow sheet showing a configuration of a seawater desalination facility of the combined power generation / seawater desalination apparatus according to the present invention.

FIG. 3 is a schematic diagram showing a configuration of a boiler.

FIG. 4 is a block diagram showing a circulation path of steam and condensed water obtained by condensing the steam.

[Explanation of symbols]

10 Example of combined power generation / seawater desalination apparatus according to the present invention 12 Thermal power generation equipment 14 Seawater desalination equipment 16 Boiler 17 Generator 18 Back pressure bleeding steam turbine 20, 21 Piping system 22 Auxiliary condenser 24 Condensed water receiving tank 26 Pure water device 28 Deaerator 30 Condensed water pump 32 Boiler water pump 34 Multi-effect evaporator device 36 Reverse osmosis membrane device 38 Evaporator 40 Seawater pump 42 Steam ejector 44 Condenser 46 Seawater sprinkler 48 Seawater preheater 50 Condensed water collection Water pipe 51 Supply pipe for driving steam for steam ejector 52 Receiving plate 54 Seawater filtration device 56 Reverse osmosis membrane 60 Hopper 62 Furnace 64 Steam drum 66 Evaporation tube group 68 Cyclone 70 Chimney 72 Superheater 76 Air preheater 78 Blower 80 Water drum

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Fujioka 3-7-1, Nishishinjuku, Shinjuku-ku, Tokyo Inside Tokyo Gas Engineering Co., Ltd. (72) Inventor Hiroshi Nishizawa 2--12, Tsurumichuo, Tsurumi-ku, Yokohama-shi No. 1 Chiyoda Chemical Construction Co., Ltd. (72) Inventor Yo Yoyamada 2-1-1, Tsurumi Chuo, Tsurumi-ku, Yokohama

Claims (5)

[Claims] 1. A boiler for generating steam, and a back-pressure steam for generating electricity by rotating a generator by the steam generated by the boiler and generating a back-pressure steam of 0.25 to 0.5 kg / cm ² abs. A thermal power plant having a turbine, a steam chamber, a condenser and a plurality of evaporators having a seawater sprinkler for sprinkling seawater in the condenser in the steam chamber, respectively, A seawater desalination facility consisting of a multi-effect evaporator unit connected to the condenser of the evaporator in communication with the condenser of the evaporator, and the backpressure steam from the backpressure steam turbine is condensed in the first stage evaporator of the seawater desalination facility The seawater sprinkled from the seawater sprinkler is evaporated in the steam chamber by the heat of the steam condensed in the condenser, and the evaporated steam is introduced into the condenser of the next-stage evaporator. If you use steam as a heat source to evaporate seawater The condensed water evaporated vapor from seawater obtained by condensing in the condenser recovered by water as fresh water, whereas,
A combined power generation / seawater desalination apparatus characterized in that condensed water of back-pressure steam condensed in the first-stage evaporator is recovered and supplied to the boiler as boiler water. 2. A thermal power generation facility is provided with an auxiliary condenser for condensing surplus back-pressure steam from the back-pressure steam discharged from the back-pressure steam turbine as the amount of desalination of the seawater desalination facility is reduced. Item 2. A power generation / seawater desalination combined device according to Item 1. 3. The seawater desalination facility has a reverse osmosis membrane device for separating into permeate having a low salt concentration and salt water having a high salt concentration by using a reverse osmosis membrane in addition to a multiple effect evaporator device. The power generation system according to claim 1 or 2, wherein power required for operation of the reverse osmosis membrane device is supplied from a thermal power generation facility.
Seawater desalination combined equipment. 4. The boiler of a thermal power plant is a circulating fluidized-bed boiler using solid fuel or solid industrial waste as fuel for combustible waste as a main raw material. The combined power generation / seawater desalination apparatus according to any one of the preceding claims. 5. A back-pressure steam turbine, wherein different-pressure steam is used for driving steam for an ejector for degassing the seawater supply system of a seawater desalination facility and medium-pressure steam used as degassing steam for boiler feedwater. The combined power generation / seawater desalination apparatus according to any one of claims 1 to 4, wherein the apparatus is a bleed back pressure steam turbine for bleeding.