JPS63201405A - Circulation system type steam feeder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Objective of the Invention) (Industrial Application Field) The present invention relates to a circulation system type steam supply device that recovers used steam as drain and returns it to the boiler. This invention relates to a circulation system type steam supply device with enhanced impurity removal function.

(Prior Art) This type of circulation system type steam supply apparatus is frequently used from the viewpoint of improving thermal efficiency, and is applied, for example, to heating buildings or driving turbines. Recently, as buildings and turbines have become larger, circulation system type steam supply devices have also become larger.

FIG. 8 shows a conventional example of such a circulation system type steam supply device.

Superheated steam generated by the operation of the boiler 1 is sent to a load 3 through a steam pipe 2 and used for work.

The steam used in the load 3 becomes saturated steam or wet steam, becomes a two-phase flow in which steam and condensed water are mixed, passes through the used steam pipe 4, and is guided to the steam trap 5. Steam and condensed water are separated in the steam trap 5 and transferred to a flash tank 6. Note that, in reality, the load 3 and the flash tank 6 are provided in multiple systems, but only one system is shown for ease of explanation. The inside of the flash tank 6 is at atmospheric pressure, and hot water of about 100° C. is stored therein. The steam in the flash tank 6 is cooled by a flash tank condenser 7 provided above the flash tank 6 and returned to the flash tank 6 in the form of water droplets.

The hot water in the flash tank 6 is transferred to one boiler water tank 10 through a transfer pipe 9 by a condensed water transfer pump 8.

The water in the boiler water supply tank 10 is returned to the boiler 1 by the boiler water supply pump 11 through the boiler water supply piping.

By the way, in such a circulation system type steam supply device, the inner surfaces of the pipes, valves, traps, etc. are severely eroded, especially in the used steam pipes 4 and steam traps 5 that are in contact with the two-phase flow of steam and condensed water, and the eroded materials A large amount of impurities such as dirt and rust flow into the flash tank 6. When these impurities are brought into the boiler 1 through the boiler water supply tank 10, the impurities such as iron (Fe) and chromium (Cr), which are the piping materials, are removed.
), nickel (Ni), copper (Cu), zinc (Zn), etc., deposit in the boiler 1 and cause scaling, or react with the boiler material to cause corrosion of the can body.

In particular, in a circulating system type steam supply device, impurities are continuously supplied to the boiler 1, and the impurity concentration in the boiler can water tends to be high.

On the other hand, the water quality of boiler 1 is Japanese Industrial Standard (JIS) B82.
23, there is a strict requirement that the total evaporation residue concentration of impurities alone be 2 oppm or less at maximum. Particularly in high-temperature, high-pressure boilers, the operating conditions for the heat exchanger tubes and the components of the can are severe, so if the water quality deteriorates due to the introduction of impurities, the can material is likely to corrode even after a short period of operation.

In the case of large boilers, there are a large number of heating equipment and turbine equipment that use steam, so the inability to operate due to corrosion will be widespread.

As a conventional countermeasure, as shown in FIG. Boiler can water is transferred to boiler blow water treatment equipment 1 using W14.
5, and at the same time injecting make-up water containing no impurities into the boiler feed water tank 10 from the make-up water injection device 16.

(Problems to be Solved by the Invention) However, it is extremely troublesome to adjust the injection amount of the anticorrosive agent to match the water quality of the boiler canned water. Moreover, the Poirapu water treatment device 15 requires large-scale equipment.

Therefore, these measures increase operating costs, equipment costs, etc.

On the other hand, simply installing a filtration device in a water supply system is considered inappropriate for a circulation system type steam supply device where the temperature of the water supply is high, partly because the heat resistance of filter media and the like is generally low. Note that lowering the total supply water temperature to a low temperature suitable for the filter medium is also not preferable for the device, which aims to improve thermal efficiency.

The present invention was developed in view of these circumstances, and it is possible to reduce the impurity concentration in boiler feed water while maintaining the characteristics of high thermal efficiency, thereby reducing boiler corrosion and reducing the amount of anticorrosive injection. It is an object of the present invention to provide a circulation system type steam supply device that can greatly contribute to reducing the amount of boiler blow water and, in turn, reducing operating costs and equipment costs.

[Structure of the invention]

(Means for solving the problems) The present invention provides a boiler, a steam usage load, a flash tank,
In a circulation system type steam supply device that includes a boiler feed water tank and a boiler feed water pump, and has a closed pipe line in which these are sequentially connected to recover used steam as drain and return it back to the boiler, the flash tank or the boiler feed water tank The present invention is characterized in that an auxiliary pipe line is provided for taking out and circulating a portion of the drain, and this auxiliary pipe line is provided with a pump cooler for drain circulation and a filter.

(Function) Impurities newly generated during the two-phase flow state in the preceding stage are introduced into the flash tank or boiler feed water tank. A portion of this impurity-containing hot water is led into an auxiliary pipe, cooled and filtered, and this action is carried out continuously. The amount of water to be cooled only needs to be set as much as is necessary for filtration.
The overall decrease in thermal efficiency is small. On the other hand, impurities are removed each time the water is supplied to the filter, and the impurity concentration in the boiler feed water is sufficiently reduced.

Note that a flash tank is usually installed for each load system, and a predetermined number of boiler water tanks are installed corresponding to the boilers, so the auxiliary pipes for filtration are the most efficient, considering the scale of the entire steam supply system. You can choose the desired layout.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 6.

A load 23 such as a heater or a turbine is connected to the boiler 21 via a steam pipe 22, and the load 23 is connected to a used steam pipe 2.
A steam trap 25 is connected via 4. The steam trap 25 is connected to a flash tank 26 whose upper part is connected to a flash tank condenser 27 and its lower part to a boiler feed tank 30 via a transfer pipe 29 with a condensate transfer pump 28. . and,
The boiler water supply tank 30 is connected to the boiler 21 by a boiler water supply pipe 32 including a boiler water supply pump 31.

In this device, an auxiliary conduit 33 in the form of a closed conduit is provided extending from the bottom to the top of the flash tank 26 to take out and circulate a part of the condensate in the flash tank 26.

A circulation pump 34, a cooler 35, and a filter 36 are arranged in the auxiliary pipe line 33 in this order from the lower side of the flash tank 26. The cooler 35 cools water at a temperature of about 100° C. under the condition of the water amount set by the circulation pump 34.
It has the ability to cool down to 0 to 60'C.

The filter 36 is of a hollow fiber membrane filter type, and its schematic configuration is shown in FIG. 2. That is, the filter 36 is a vertically long tank 3.
The interior of the filter 7 is divided into upper and lower sections by a horizontal flange 38, and a hollow fiber membrane filter element 39 is suspended from the flange 38. The water introduced into the lower part of the tank 37 passes through the hollow fiber membrane filter element 39 to the tank 37.
A filtration action takes place as it flows to the top.

FIG. 3 shows the structure of the hollow fiber membrane filter element 39 in detail, and FIGS. 4 to 6 show further enlarged cross-sectional structures of a part thereof, together with the flow state. This hollow fiber membrane filter element 39 is made of synthetic resin such as polyethylene, and has filter holes 40 with a diameter of 0.1 μm or less, and impurities 41 such as ordinary scale and rust can be directly filtered out. Pre-coating such as these is considered unnecessary. Furthermore, the diameter of the filter holes 40 is sufficiently small to prevent clogging with impurities 41, allowing stable continuous operation for a long period of time.

A backwash drain valve 42 and a drain pipe 43 are provided at the bottom of the filter 36, and when a certain amount of captured impurities is reached, the flow is reversed and backwash is performed to remove the impurities from the drain pipe 43. It is designed to be able to be discharged to the outside.

Next, the effect will be explained.

Superheated steam generated by the operation of the boiler 21 is transferred to the steam pipe 2.
2 to the load 23 and used for work. The steam used in the load becomes saturated steam or wet steam, becomes a two-phase flow in which steam and condensed water are mixed, and is transferred to the used steam pipe 2.
4 and is led to a steam trap 25. Steam and condensed water are separated in the steam trap 25 and transferred to a flash tank 26. The inside of the flash tank 26 is kept at atmospheric pressure, and heat soaking at about 100° C. accumulates therein. The steam in the flash tank 26 is cooled by a flash tank condenser 27 provided above the flash tank 26 and returned to the flash tank 26 in the form of water droplets.

A portion of the water in the flash tank 26 is guided to the auxiliary pipe 40 by the circulation pump 34.

The water led to the auxiliary pipe 40 is heated to 50°C by the cooler 35.
It is cooled to ~60°C and flows into filter 36. In the filter 36, the hollow fiber membrane filter element 39 filters 0.
Impurities 41 with a size of 1 μm or more are removed, and the purified water is returned to the flash tank 26 by this filtration action.

During filtration, the water flowing into the filter 36 from the flash tank 26 is cooled from 100°C to 50°C to 60°C, so the hollow fiber membrane filter element 39 made of resin is used at temperatures below its heat-resistant temperature. There is no adverse thermal effect. Further, the amount of water to be cooled is a portion of the inside of the flash tank 26, and the water temperature within the flash tank 26 does not drop significantly, and the thermal efficiency on the boiler water supply is sufficiently maintained.

The water in the flash tank 26 is then transferred to the boiler feed water tank 30, from where it is further returned to the boiler 21. In this case, the impurity concentration in the boiler feed water is sufficiently reduced, and the can body etc. are not adversely affected. Therefore, it is possible to downsize or omit the conventionally required anticorrosive injection device, boiler can water blowing device, make-up water injection device, and the like.

If impurities enter the filter 36 beyond a certain level, the flow direction of the water is reversed and the backwash drain valve 42 is opened, as shown in FIG. All you have to do is wash it. Thereafter, the filtration action can be reproduced using the regenerated hollow fiber membrane filter element 39.

According to the embodiments described above, impurities carried into boiler feed water can be significantly reduced without reducing thermal efficiency. As a result, the quality of boiler canned water remains highly pure and stable, corrosion of boiler heat transfer tubes and cans is prevented, and the need for anticorrosive injection equipment, make-up water piping and valves for replacing canned water, and boiler blow water treatment equipment can be eliminated. It becomes possible to reduce the scale, simplify the equipment, and facilitate operation.

In addition, since the drain from the impurity filter is returned to the circulation system, there is no loss of water, which is economical.

Note that the impurity removal filter 36 has filter holes 40 with a diameter of 0.
．． By having the hollow fiber membrane filter element 39 of 1 μm or less, almost all impurities can be removed. Further, the backwash water discharged from the filter 36 only flows out filtered impurities, and the amount of waste is relatively small, and the disposal cost is low.

In the above embodiment, the auxiliary pipe line 33 for filtering is provided in the flash tank 26, but the present invention is not limited thereto, and may be provided in the boiler water supply tank 30, for example, as shown in FIG. The configuration other than the mounting position of the auxiliary conduit 33 is the same as that of the previous embodiment, so corresponding parts in the figure are given the same reference numerals as in FIG. 1, and their explanation will be omitted.

In the embodiment shown in FIG. 7, since the boiler feed water tank 30 is a large tank with only one provided in the steam supply system,
The cooler 35 and the filter 36 may also be selected with capacities corresponding to these. As a result, substantially the same effects as those of the embodiment described above can be achieved. The configurations of each embodiment can be selectively applied to actual equipment depending on the scale.

〔Effect of the invention〕

As described above, according to the present invention, the flash tank or boiler feed water tank of the circulation system type steam supply device has
An auxiliary pipe line is installed to take out a portion of the drain, cool it, and filter it, reducing the amount of impurities brought into the boiler without significantly reducing thermal efficiency, improving reliability in boiler operation. , ease of operation, etc. can be achieved with a relatively simple configuration and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention, FIG. 2 is a schematic sectional view showing the filter of FIG. 1, and FIG. 3 is a sectional view showing an enlarged filter section of FIG. 2. FIG. 4 is a partial enlarged view of FIG. 3, FIGS. 5 and 6 are explanatory diagrams showing the filtration action, FIG. FIG. 2 is a system configuration diagram showing a conventional example. 21...Boiler, 23...Load, 25...Steam trap, 26...Flash tank, 30...Boiler feed water tank, 31...Boiler feed water pump, 33...
- Auxiliary pipe line, 34... Circulation pump, 35... Cooler, 36... Filter, 39... Hollow fiber membrane filter element. Figure 1 Figure 113 Figure 4 Figure 8

Claims (1)

[Claims] 1. A closed pipe line that includes a boiler, a steam usage load, a flash tank, a boiler water supply tank, and a boiler water supply pump, and connects these in sequence to recover used steam as drain and return it to the boiler. In the circulation system type steam supply device, an auxiliary pipe line is provided in the flash tank or the boiler feed water tank for taking out and circulating a part of the drain, and a pump cooler and a filter for drain circulation are installed in the auxiliary pipe line. A circulation system type steam supply device characterized by: 2. The circulation system type steam supply device according to claim 1, wherein the filter has a hollow fiber membrane filter with a filtration pore diameter of 0.1 μm or less.