JPS6036829B2 - Condensate treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a condensate treatment method and apparatus for removing impurities present in condensate in order to prevent scale formation and corrosion in boilers and turbines.

In general, condensate desalination equipment uses strongly acidic intestine ion exchange resin H
The other method is the H cycle treatment method, in which a mixture of the OH form and the OH form of a strongly basic anion exchange resin is used, and the cation exchange resin is regenerated when it is saturated with ammonia in the condensate. There is an NH3 cycle treatment method in which the treatment is continued using the resin substituted into the ammonia form even after the ammonia in the condensate has broken through.

Recently, many condensate desalination apparatuses have adopted N-ratio cycle condensate treatment, which requires less regeneration frequency, from the viewpoint of saving regeneration chemicals and operational management. However, the operation of the NH3 cycle is subject to various limitations different from those of the H cycle, and there are drawbacks such as the equipment being complicated and regeneration taking a long time, so it cannot necessarily be said that it is a perfected technology. The current situation is that there is no such thing. In the conventional N-horse cycle, ammonia in the desalination tower inflow is not adsorbed and removed in the desalination tower and is directly included in the outflow water.
If impurities remain in the resin packed in the regenerative desalination tower, these impurities react with ammonia in the condensate, eluting the impurities from the resin and mixing with the treated water, degrading the quality of the treated water. It turns out.

For example, when regenerating an anion exchange resin with caustic soda, some of the intestinal ion exchange resin comes into contact with the caustic soda and becomes Na form, which reacts with ammonia in the condensate during the water flow process, adding Na to the treated water. One example is leakage. Methods to reduce this sodium leakage include passing slaked lime solution and using ammonia water, but both use special chemicals and require a long time for regeneration. There was a drawback. The present invention aims to eliminate the drawbacks of these conventional condensate desalination methods and provide an effective treatment method for stably obtaining treated water of extremely high purity not only in H cycle but also in NH3 cycle operation. There is.

Furthermore, another object of the present invention is to provide an effective treatment method that can significantly reduce the amount of regenerant in a condensate desalination device and facilitate maintenance.

The present invention uses a condensate treatment device consisting of an ion-exchanged resin tower 1, a precoat furnace filtration machine 3, and a hot bed desalination tower 5 to treat high-pressure poller condensate, and remove dissolved solids and suspended solids in the condensate. In the method of removing substances, when treating condensate containing a large amount of impurities, such as when starting a boiler, the condensate is passed through a first column filled with granular intestinal ion exchanger resin, and then After processing by passing water through the pre-coat filter 3 of the second tower, which is pre-coated with a mixture of powdered cation and anion exchange resins,
It is characterized in that water is then passed in series to the moat bed type desalination tower 5 of the third tower, which has a mixed bed type resin layer 6 containing a mixture of granular H type resin and OH type resin, to perform the final finishing. It is.

Normally, when a boiler is started, the main component of suspended solids contained in condensate is iron oxide, and approximately 90% of these are removed by the overaction of the adsorption furnace in the H-type cation-converting resin layer 2. The removal rate of suspended solids differs depending on the ionic form of the resin, and the removal rate of NH4 type resin is 10 to 20% lower than that of H type resin. From this, in order to keep the turbidity concentration of the condensate flowing into the second column as low as possible, the ionic form of the resin in the first column is preferably H type. The water flowing out of the cation exchange resin tower 2 in the first tower contains some suspended solids, but these are almost completely removed by the pre-coating furnace filter 3 pre-coated with powder ion exchange resin in the second tower. removed. When condensate containing high concentration of impurities is directly passed through the precoat layer 4 of powdered ion exchange resin, the differential pressure in the precoat filter 3 increases rapidly, and the precoat layer 4 must be frequently renewed. It was not economical to replenish expensive powdered ion exchange resin.
When most of the insoluble substances are removed in the cation exchange resin column 1 in the first column as in the present invention, the amount of water treated per unit weight of precoat material in the precoat furnace filtration machine 3 in the second column increases significantly. The operational management of condensate treatment equipment is of utmost importance, as the first tower contaminated with insoluble substances can be restored to its turbidity collection capacity by simple backwashing with water or scrubbing with water and air. This makes it easy to use. After the boiler is started, the purity of the condensate flowing into the condensate treatment device gradually increases as time passes, and the purity of the second headwater effluent also increases accordingly.

When such normal operation starts, the water flow to the desalination tower 5 of the third tower is stopped from the time when the second tower outflow water satisfies the boiler feed water standard value based on the water quality measurement of the second tower outflow water. Then, a method is used in which condensate is treated in the first and second towers. During normal operation, not only the granular resin in the first tower, which was in the H form at the beginning of water flow, but also the powdered cationic cross-resin in the second tower gradually changed to the N ratio form as the water flow increased. However, it is possible to continue processing and perform condensate treatment in the ammonia cycle. If an increase in dissolved solids is detected in the inflow condensate by measuring the quality of the condensate flowing into the condensate treatment equipment, the second tower effluent is immediately passed to the concentrated bed demineralization tower 5 of the third tower. Switch to Since the mixed bed in the third column is always in the ionic form of H type and OH type, the method of the present invention is sufficient to prevent an increase in dissolved salts due to a major condenser leakage accident. can be dealt with with ease. In the event of a leak in the condenser where the salt concentration is relatively low, it is possible to treat it with only the pre-coated layer 4 of powdered mixed resin in the second column, but for safety reasons, if the salt concentration of the condensate increases, the third column should be used. A method using . Another feature of the present invention is that condensate can be treated continuously.

In other words, in the conventional condensate treatment equipment using only a mixed-bed demineralization tower, it was necessary to temporarily stop the water flow to the demineralization tower 5 when regenerating the resin, but the method of the present invention According to , continuous treatment is easily possible by switching the valves, so there is no need for a standby demineralization tower.
For example, while the cationic exchange resin 2 in the first column is being backwashed or regenerated, the condensate is bypassed from the first column and then passed to the second column, where the necessary water is continued. In this case, water can be passed to the third tower for treatment. When the second tower is renewing the precoat layer, the condensate is passed from the first tower to the third tower for treatment, and if the third tower is regenerated during normal times,
It becomes possible to perform continuous operation treatment without interruption of condensate treatment due to regeneration of the resin in the third column. In one embodiment of the illustrated example of the present invention, a cationic mixed dried sardine resin tower 1 with a cationic mixed resin layer 2, a precoated furnace 3 with a precoated furnace layer 4, and a mixed bed type resin layer 6 are provided. In a condensate treatment device in which a certain hotbed type demineralization tower 5 is connected in series through a piping route with a valve, an inflow condensate water quality monitoring meter Mi is connected to each piping route.
, pre-coat furnace filtration machine effluent water quality monitor Mc, mixed bed desalination tower effluent water quality monitor Me and valves 7, 8, 9, 10, 11
, 12, 13, 14, 15, 16, and 17 are deployed.

Generally, in a condensate desalination apparatus, it is common to divide the water to be treated into a plurality of treatment apparatuses and pass the water through the treatment apparatuses. Although the method of the present invention similarly has a plurality of processing sequences, only one sequence is shown here, omitting the other sequences. When the boiler is started, the condensate that has passed through valve 7 and whose water quality has been checked by the inflow condensate water quality monitor Mi is introduced into the cation exchange resin tower 1 through valve 8, and enters the ion exchange resin layer 1. After passing through the filter 2, suspended solids and cations are removed by the adsorption furnace filtering action, and then introduced into the precoat filter 3 via valves 9 and 11.

After passing through the pre-coat layer 4, which serves as a resin overlay during the positive and negative ion phase of the powder, the water quality is measured by a water quality monitor Mc, and then enters the mud bed desalination tower 5 through valves 12 and 15, where the water quality is measured. The water quality is tested by the monitor Me, and the water is led out of the system through the valve 16. When the differential pressure in the resin column 1 of the first column exceeds the set value or the resin layer 2 in the column becomes contaminated, valves 8 and 9 are closed and valve 10 is opened to transfer condensate to the first column. The water is passed to the second tower by bypassing the tower. Although the regeneration method is not shown in Fig. 1, the contaminated resin layer 2 in the first column can be backwashed, scrubbed, or treated with tin acid by using an in-column regeneration device or an external regeneration device. After performing the regeneration, valve 10 is closed, valves 8 and 9 are opened, and the process returns to the water flow process again. In this way, even during the regeneration of the resin in the first column, continuous treatment is possible without stopping the operation of the condensate treatment device. In this case, if the resin in the first column is H-type, about 90% of the iron oxides in the inflow condensate will be removed in the first column, and if the resin is N-type, 70-80% of the suspended particles will be removed. removed. Next, after the boiler is started, the purity of the inflow condensate gradually increases, and the purity of the second column outflow water increases accordingly.
When it is confirmed by the water quality monitor Mc that the quality of the second column effluent water satisfies the boiler water supply standard value, valves 15 and 16 are closed and valves 13 and 17 are opened to bypass the third column and perform condensate treatment. Shift to normal operation.

During normal operation, both the 1st tower and the 2nd *
It is possible to arbitrarily adopt either a cycle or an NA cycle processing method. When regenerating the first column during normal times, condensate is treated only in the second column. Also,
When renewing the precoat layer 4 of the second column, the valves 11 and 1
2 and 17, and open valves 14, 15, and 16, the condensate is temporarily passed from the first column to the third column, and when the precoating operation in the second column is completed, the condensate is returned to the first column. A method is used to pass water from the main tower to the second tower. Although the precoating operation in the second column is not shown in the drawings, a precoat layer is formed by a conventional method in which a slurry prepared by mixing powdered cationic and anionic exchange resins in water is applied to the precoat support. If the inflow condensate water quality monitor Mi detects an increase in dissolved salt in the inflow condensate, immediately close the valves 13 and 17.
Valve 15. , 16 to allow the second column effluent to pass to the third column, the mixed-bed desalination column 5, to continue the treatment. Regarding the regeneration of the hot bed type resin layer 6 of the third column, although not particularly shown in the figure, it can be carried out by either an in-column regeneration method or an off-site regeneration method, and the method is a normal H cycle condensate treatment. The method used in the equipment may be followed, and special chemicals or strict separation of mixed resins are not required.

Further, if the regeneration timing is selected when the third tower is in a standby state, there is no need to stop the operation of the condensate treatment equipment for regenerating the third tower. According to the method of the present invention, under normal conditions, condensate treatment is performed through a granular resin layer with extremely low impurity content and a powder resin precoat layer, so special chemicals and regeneration operations are required not only in the H cycle but also in the operation of the ammonia cycle. Highly purified treated water can be obtained without using

As described above, according to the method of the present invention, in cases where condensate purity is low, such as during boiler startup and condenser leakage,
Condensate is treated continuously by series treatment of intestinal ion exchange resin layer, powdered ion exchange resin furnace layer, and moat bed type resin layer, and also in normal times when condensate purity is high, by two-stage treatment excluding the hot bed tower. processing efficiency can be significantly increased by
The use of regeneration chemicals in the condensate treatment equipment can be drastically reduced, operation and maintenance is easy, and the drawbacks of conventional condensate desalination methods have been eliminated, resulting in extremely high purity even in H cycle as well as NH3 cycle operation. The advantage is that a large amount of treated water can be obtained stably and the treatment cost can be reduced economically.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a system explanatory diagram showing one embodiment of the present invention. 1...Resin column for intestinal ion exchange, 2...Cation exchange resin layer, 3...Pre-coating furnace filter, 4...Pre-coating furnace filter, 5...Mixed bed desorption Salt tower, 6...
・Mixed bed type resin layer, 7, 8, 9, 10, 11, 12, 13
, 14, 15, 16, 17... Valve, Mi...
...Inflow condensate water quality monitor, Mc...Precoat furnace filtration machine effluent water quality monitor, Me...Moat bed type desalination tower effluent water quality monitor.

Claims (1)

[Scope of Claims] 1. Impurities in condensate are removed in a condensate treatment process in which boiler condensate is passed through a pre-coated filter pre-coated with powdered ion-exchange resin and an ion-exchange resin column filled with granular ion-exchange resin to remove impurities in condensate. During normal times when the amount is small,
An adsorption filtration process in which condensate is passed through a first column filled with granular cation exchange resin, followed by precoat filtration in a second column in which powdered cation exchange resin and anion exchange resin are mixed and precoated. In the pre-coat filtration step, in which water is passed through the machine in series for treatment, and when the boiler starts up or the condenser leaks, when the amount of impurities in the condensate is relatively large, the condensate treated in the first and second columns is A condensate treatment method comprising a desalination step in which water is passed through a mixed demineralization tower of a third tower filled with a mixture of granular cation exchange resin and anion exchange resin. 2. The adsorption filtration step is carried out in the first column filled with H type or NH_4 type cation exchange resin, and the precoat filtration process is performed using a combination of H type and OH type or NH_4 type and OH type. the desalting step is carried out in a second column with a mixed bed of a combination of H-form cation exchange resin and OH-form anion exchange resin; The condensate treatment method according to claim 1, wherein the condensate treatment method is performed. 3. While the pre-coat filtration step backwashes or regenerates the resin in the first column, the condensate is treated alone without going through the adsorption filtration step, or in series with the desalination step. The condensate treatment method according to claim 1 or 2, which is carried out in combination with. 4. While the pre-coat filtration step pre-coats a new filter aid, the second column is bypassed and the condensate is processed from the adsorption filtration step to the desalination step, or The condensate treatment method according to item 2. 5. During the desalting step, during the regeneration of the resin in the desalting tower,
The method according to claim 1 or 2, wherein the condensate is treated in an adsorption filtration step and a precoat filtration step without going through a desalination step and is omitted from the actual condensate treatment step. Condensate treatment method.