JP2941541B2 - Equipment for maintaining low concentration of salt and potassium salt in pulp cooking chemicals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a salt and pulp cooking chemical applied to a soda recovery boiler of a pulp manufacturing plant.
The present invention relates to a device for maintaining a low concentration of potassium salt.

[0002]

2. Description of the Related Art In pulp cooking chemicals used for pulp production, salts and potassium salts are mainly brought from raw pulp wood as impurities. These impurities tend to concentrate and accumulate in the pulp and chemicals accompanying the lost chemicals that go out of the system. This concentrated and accumulated salt or potassium salt increases the circulatory load in the drug as an inert substance,
It is well known that dead loads not only reduce economics, but also significantly increase the corrosiveness of chemical recovery systems.

[0003] For this reason, a salt removal method described below has been conventionally applied to a pulp manufacturing plant. In this salt removal method, the collected ash from the exhaust gas of the soda recovery boiler is slurried using a small amount of water and a circulating liquid, and the salt is dissolved in water at a temperature of 60 to 70 ° C., and the solid content in the slurry is reduced. Separation
It is a method of collecting.

[0004] Further, in a plant that does not have a salt removal device (hereinafter, referred to as a desalination device) for performing the above-described salt removal method, the salt concentration in the collected ash is periodically measured, and the measured value is set to a reference value. In the case described above, the chemical was discharged outside the system, for example, to a pulp waste liquid treatment device.

[0005]

However, since the above salt removal method is based on the basic operation of dissolving and removing salt with water, sodium sulfate, which is a cooking chemical, is partially dissolved, resulting in chemical loss. Therefore, when operating the desalination apparatus, collecting
When the salt concentration of the ash is low, slurrying becomes difficult when the amount of added water is reduced, and chemical loss increases when the amount of added water is increased. Therefore, the operation of the desalination device is effective only when the salt concentration is high.

Further, regardless of whether or not the plant has the above-mentioned desalination apparatus, since the desalination operation or the measurement and discharge is performed periodically, for example, every eight hours even in a strictly controlled plant, appropriate system switching is performed. Could not. For this reason, the chemical loss was increased, and corrosion and failure were caused by returning the collected ash having a high salt concentration to the chemical recovery system.

The present invention has been made in view of the above circumstances, and appropriately removes collected ash having a high concentration of salt and potassium salt, minimizes the loss of pulp cooking chemicals, and improves the efficiency of work. It is an object of the present invention to provide an apparatus for maintaining a low concentration of sodium chloride and potassium salt in the obtained pulp cooking chemical.

[0008]

An apparatus for maintaining a low concentration of sodium chloride and potassium in a pulp cooking chemical according to the present invention is capable of measuring the concentration of chlorine or potassium in collected ash in a time series manner. Measuring means for measuring, when the concentration of chlorine or potassium measured by the measuring means is less than a predetermined concentration, the collected ash is sent out into a chemical system, and the concentration is not less than a predetermined concentration. means for delivering the collected ash to the system, such as a drug line outside or desalter if ash which is the collected were delivered to the grid, such as chemicals system outside or desalter by this means In this case, there is provided a means for supplying a new medicine into the medicine system according to the amount of ash sent out.

[0009]

The collected ash collected by the electric precipitator of the recovery boiler is sampled, and the concentration of chlorine or potassium is measured in a time series using a measuring means such as an ion electrode, an ion chromatograph or a fluorescent X-ray analyzer.

If the measured value is less than a predetermined reference value, the collected ash is returned to a chemical system such as an ash mixing tank, and if the measured value is more than the reference value, the collected ash is removed from a chemical system such as a pulp waste liquid treatment device. Alternatively, it is sent to a system such as a desalination device.

Further, when the measured value is equal to or higher than the reference value, a new chemical corresponding to the amount of collected ash discharged outside the chemical system is replenished, so that the salt or potassium salt in the pulp cooking chemical is always reduced to a low concentration. maintain.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the apparatus for maintaining a low concentration of salt and potassium salt in a pulp cooking chemical according to the present invention.

The electric precipitator 1 includes a recovery boiler (not shown).
Using transfer line 2 was collected ash from the ash mixing tank 3
Transfer to A line switching mechanism 4 is provided in the middle of the transfer line 2 so that the collection passing through the transfer line 2 is performed.
Depending on the salt or potassium salt concentration of the ash, which is to be transferred to the spent liquor processing unit 6 via the ash mixing tank 3 or culvert 5.

[0014] Also, on the upstream side of the line switching mechanism 4 in the transfer line 2 is sampling mechanism 7 for collecting ashes is attached performs sampling of the collecting ash weighed collecting ash sampling diluting mechanism It is sent to the ion chromatograph 9 via 8. The ion chromatograph 9 measures the concentration of chlorine or potassium in the sampled collected ash and outputs data to the arithmetic unit 10.

Further, data is sent from the weighing / diluting mechanism 8 to the arithmetic unit 10, and the arithmetic unit 10 calculates the concentration of salt or potassium in the collected ash based on these data, The result is output to 11.

Further, a chemical tank 12 containing a new chemical (sodium sulfate) is provided in the vicinity of the ash mixing tank 3, and a belt conveyor 13 is provided so as to charge the chemical into the ash mixing tank 3. Have been. The control device 11 controls the line switching mechanism 4 according to the input data.
And control of the belt conveyor 13. Next, an apparatus for measuring chlorine or potassium in the collected ash will be described with reference to FIG.

A valve 71 and a guide 72 are attached to the lower part of the transfer line 2, and guide the sampled ash to a dilution container 81. A weighing mechanism 82 is provided below the dilution container 81.
Is provided, and the result of weighing the sample is sent to the arithmetic unit 10.

The dilution mechanism 81 is provided with a line so that pure water is sent from a pure water tank 83 by using a pure water injection pump 84, and drains a sample unnecessary for measurement among the diluted samples. A discharge pump 85 for discharging to the groove is provided. Further, the collected ash sampled is stored in the dilution container 81 by the ion chromatography 9.
The sample is sent to the ion chromatograph 9 by this suction pump.

The configuration of the ion chromatograph 9, the arithmetic unit 10, and the control unit 11 is the same as that described with reference to FIG. 1, and a description thereof will be omitted. However, the control device 11 also controls the pure water injection pump 84 and the suction pump 86 in addition to the control described above. Next, the operation of the above embodiment will be described.

The ash collected by the electric precipitator 1 is usually transferred to an ash mixing tank 3 through a transfer line 2. At this time, the guide 72 is opened by opening the valve 71 for a predetermined time.
A part of the ash is led to the dilution container 81 via

Next, the weight of the sample introduced into the dilution container 81 is weighed by a weighing mechanism 82, and a pure water injection pump 84 is operated according to the weight to inject pure water from a pure water tank 83. This is for dissolving and diluting the sample within a measurable concentration range in the ion chromatograph 9 for measuring the concentration of chlorine or potassium.

The diluted solution is sent to the ion chromatograph 9 by the suction pump 86, and the concentration of chlorine or potassium in the sample solution is measured. The calculated concentration of chlorine or potassium is converted by the arithmetic unit 10 into the concentration of salt or potassium salt in the collected ash . Here, the converted salt or potassium salt concentration is a predetermined value (for example, 11
(wt% as NaCl) or more, the line switching mechanism 4 is driven to switch the output location of the transfer line 2 to the drain 5 (B side in FIG. 1), and the collected ash is discharged from the pulp wastewater outside the chemical system. It is discharged to the processing device 6. At this time, the belt conveyor 1
3 is operated to supply a new chemical corresponding to the amount of collected ash from the chemical tank 12 to the ash mixing tank 3.

The collection calculated by the arithmetic unit 10
When the concentration of the salt or potassium salt in the ash is lower than a predetermined value, the output place of the transfer line 2 maintains the state of the ash mixing tank 3 (A side in FIG. 1).

The sample solution prepared in the dilution vessel 81 is sent to the ion chromatograph 9 by a suction pump 86 in an amount necessary for concentration measurement, and the remaining sample solution is discharged to a drain by a discharge pump 85. Is done.
Further, the pure water injection pump 84 is operated as needed to wash the dilution container 81.

In the above embodiment, the ion chromatograph 9 has been described as a means for measuring chlorine or potassium in a time series. However, other means such as an ion electrode and a fluorescent X-ray analyzer may be used. It is possible. However,
In that case, it is necessary to change the pre-treatment of the sample according to the measurement means used. For example, when a fluorescent X-ray analyzer is used, the collected ash is subjected to X-
The condition of the irradiated part must be kept uniform.

[0026]

As described in detail above, according to the present invention,
In the recovery boiler salt or potassium salt are most condensed in medicaments lines, sampling the ash trapped by an electric precipitator, which is attached to the recovery boiler, by measuring the sodium chloride or potassium salt concentration at predetermined time intervals, capturing It can be used as a monitoring device because it can monitor the change over time of the salt or potassium salt concentration during ash collection .

Further, the measured concentration is determined by a predetermined collecting method.
When exceeding the concentration of acceptable salt or potassium salt in ash, automatically discharging the collected ash out chemical system, in which newly supplied chemicals in accordance with the ejected collected ash By doing so, it is possible to efficiently remove trapped ash having a high concentration of salt or potassium salt and to appropriately supply a new chemical. This minimizes the loss of pulp cooking chemicals and prevents the collection ash with high salt and potassium salt concentrations from circulating outside the chemical system, thereby preventing corrosion and dust clogging in the system. it can.

Further, since the apparatus for maintaining a low concentration of salt and potassium salt in pulp cooking chemicals can be operated as an automatic measuring apparatus, maintenance such as replenishment of eluent and pure water used in ion chromatography is extremely difficult. Conventionally, complicated operations such as sampling of collected ash at regular time intervals, analysis of salt concentration, discharging of collected ash as needed, replenishment of new chemicals, etc. are not required, and work efficiency can be improved. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus for maintaining a low concentration of salt and potassium salt in a pulp cooking chemical according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an apparatus for measuring chlorine or potassium in collected ash in the embodiment.

[Explanation of symbols]

1 ... Electric dust collector, 2 ... Transfer line, 3 ... Ash mixing tank,
4 line switching mechanism, 5 drainage channel, 6 pulp waste liquid treatment device, 7 sampling mechanism, 8 weighing / dilution mechanism, 9 ion chromatography, 10 arithmetic device, 11
... control device, 12 chemical tanks, 13 ... belt conveyor,
71: valve, 72: guide, 81: dilution container, 82:
Weighing mechanism, 83: pure water tank, 84: pure water injection pump,
85 ... discharge pump, 86 ... suction pump.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References Pulp and Paper Technology Association “Handbook of Paper and Pulp Technology” (s57) p.111 (58) Fields studied (Int. Cl. ⁶ , DB name) D21C 11/12 G01N 33 / 34

Claims (1)

(57) [Claims] 1. A measuring means for measuring the concentration of chlorine or potassium in ash collected in a time-series manner, and when the concentration of chlorine or potassium measured by the measuring means is less than a predetermined concentration, Sending the collected ash into the chemical system,
In the case of more than a predetermined concentration and means for delivering the collected ash medicines system outside or system of desalter like ashes which is the collection of such chemical systems outside or desalter by this means Means for supplying a new chemical into the chemical system according to the amount of ash sent when the ash is sent to the system, the apparatus for maintaining a low concentration of sodium chloride and potassium salt in pulp cooking chemicals.