JPS6066135A - Specific gravity measuring method of ammonium sulfate mother liquor in crystallizing tank - Google Patents

Abstract

PURPOSE:To measure exactly specific gravity of a mother liquor by connecting a pressure leading pipe to a charging pipe inserted from a tank wall and making water of a fixed quantity flow, in two parts being different in a depth from the surface of an ammonium sulfate mother liquor of a crystallizing tank, and by a back pressure difference and a depth difference of an inflow water of the two parts by a differential pressure transmitter connected to the pressure leading pipe. CONSTITUTION:Charging pipes 21, 22 inserted through tank walls of each different depth such as h1 and h2 from the surface of a mother liquor or an ammonium sulfate crystallizing tank 1 are provided, and pressure leading pipes 31, 32 are cnnected to each of them. A fixed little quantity of water is made to flow in the pressure leading pipes 31, 32 through flow meters 4, 4 from a water supply pipe 5, and a differential pressure transmitter 6 is provided on the way of the pressure leading pipes 31, 32. By using such a device, water of a fixed quantity is made to flow into a motor liquor from the tips of the charging pipes 21, 22, and a differential pressure P2-P1 of both the pipes is measured continuously. In this way, it does not occur that the mother liquor flows in from the tips of the charging pipes 21, 22, and the crystal closes the pipe end, and accordingly, the specific gravity can always be measured continuously and stably and with a high accuracy without executing an operation stop, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the specific gravity of ammonium sulfate mother liquor in a crystallization tank in a process for producing granular ammonium sulfate.

In the process of producing granular ammonium sulfate, ammonium sulfate mother liquor is introduced into a crystallization tank and heated and circulated between the evaporator to evaporate water, concentrate the ammonium sulfate mother liquor, and grow ammonium sulfate crystals to produce granular ammonium sulfate. are doing.

The particle size of the product ammonium sulfate in the above granular ammonium sulfate manufacturing process is determined by the ammonium sulfate slurry concentration at the time of extraction from the crystallization tank to the centrifuge. However, since it is impossible to measure the slurry concentration in the ammonium sulfate mother liquor, the slurry concentration is estimated by measuring the specific gravity of the ammonium sulfate mother liquor in the crystallization tank, and the amount withdrawn to the centrifuge is controlled.

In this way, particle size control is performed by keeping the slurry concentration in the ammonium sulfate mother liquor at a predetermined value, so it is necessary to continuously measure the specific gravity of the ammonium sulfate mother liquor. As one of the conventional specific gravity measurement methods, as shown in Fig. 1, when the difference in depth from the surface of the mother liquor in the crystallization tank (1) reaches a predetermined value, a pressure receiving part (7) is placed on the tank wall at position 7. (7) and are connected to the remote diaphragm type differential pressure transmitter (9) via the cabillary tube (8), respectively, and the depth difference (h2-h,) and the pressure difference (p
, -p,), the specific gravity was continuously measured.

However, in the above measurement method, since the pressure receiving part (7) (7) is installed on the tank wall, the transmitter (9) and the pressure receiving part (7) are installed on the tank wall.
) When inspecting (7), it is necessary to stop operation of the crystallization tank. Furthermore, even if an abnormality such as adhesion of ammonium sulfate crystals to the pressure receiving part occurs during operation, the operation must be stopped and inspected, which hinders stable operation of the crystallization tank.

In order to eliminate such drawbacks, the inventors, as a result of various studies, came up with a solution based on the depth difference and pressure difference caused by the air purge method. That is, as shown in Figure 2, the depth,
Insert the pub-to-pipe αOQl into the tank wall position, and connect the air and purge air (to) with the purge pipe αυ.
Connect a differential pressure transmitter (6) midway through the piping to connect the pub-to-pipe (
When a certain amount of air is bubbled into the mother liquor from 10αQ, the back pressure (bubbling pressure) of the air changes depending on the depth and specific gravity of the two pub-to-tubes, and the pressure difference (p2-p,
) is detected by the differential pressure transmitter (6).

According to this method, if the indicated value is abnormal, it can be inspected without stopping the operation, but since the purge air is compressible, the hunting of the indicated value increases as the specific gravity increases. Attempts were made to reduce the size of the inside by installing an aperture or a buffer tank, but no adjustments were made. In addition, since ammonium sulfate crystals adhere to the tip of the buff tube, it is necessary to provide a cleaning water pipe (6) and periodically charge cleaning water for cleaning. Furthermore, when the air is stopped, the mother liquid flows back into the purge pipe α◇.

Due to these drawbacks, it is difficult to employ it industrially. Therefore, the inventors succeeded in preventing the contamination of mother liquor by flowing a certain amount of water through a pressure impulse pipe instead of the purge air, and measuring the specific gravity by detecting the differential pressure of the back pressure. It was found that stable operation was possible without the occurrence of tip clogging.

That is, this invention involves connecting a pressure pipe to a charging pipe inserted from the tank wall at two locations at different depths from the surface of the ammonium sulfate mother liquor in a crystallization tank in the process of producing granular ammonium sulfate, and allowing a certain amount of water to flow. The gist is to detect the differential pressure between the back pressures of the inflow water at the two locations using a differential pressure transmitter connected to the pressure guiding pipe, and to convert the difference between the differential pressure and the depth into specific gravity.

Next, an embodiment of the present invention will be described with reference to FIG.

Charge tubes (21) and (22) are inserted through the tank wall at two different depths from the ammonium sulfate mother liquor surface of the crystallization tank (1).
), each connected to the impulse pipe (8,) (8,), and connected to the water supply pipe (5) via the flow meter (4) (4) to flow a certain amount of water, and Pressure pipe (81) (
82), the specific gravity of the mother liquor is continuously measured using a device equipped with a differential pressure transmitter (6).

That is, water is supplied from the supply pipe (5) to the impulse pipe (81) (8
,), and let it flow into the mother liquor from the tip of the charging tube (2+) (2J), and the differential pressure (p, -p,) of the back pressure is detected by the differential pressure transmitter (6). However, the specific gravity is calculated based on this differential pressure and the difference in depth.

By carrying out this invention, if a certain amount of water is constantly flowing through the impulse pipe and charging pipe, the depth will increase as described above, and
The pressure difference between the pressures p and p2 is measured. Moreover, the tip of the charging tube is not clogged with mother liquor (and mother liquor does not flow into the tube, so there is no need to stop operation).The specific gravity can be measured continuously and stably.Therefore, the crystallization tank can be operated stably. Furthermore, the amount of water flowing is extremely small compared to the ammonium sulfate mother liquor in the crystallization tank, and does not interfere with concentration.

Example: In a crystallization tank in the by-product ammonium sulfate manufacturing process at a coke factory, specific gravity measurements were carried out simultaneously using the air purge method and the method of this invention by flowing water, with a depth difference of 1 m from the surface of the ammonium sulfate mother liquor. . The chart record of the measurement results is recorded in the fourth
As shown in the figure. In this case, the amount of water inflow is 301/HX
There were 2 locations.

As shown in FIG. 4, in the case of the air purge method, hunting became large when the specific gravity of the ammonium sulfate mother liquor rose above a certain value, and sensitivity adjustment was ineffective.

However, in the case of the present invention, hunting was small, measurement could be performed stably, and there was no F trouble caused by adhesion of ammonium sulfate crystals.

Furthermore, the inflow of water at 60β/H had no effect on the concentration of the crystallization tank.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a conventional remote seal type mother liquor specific gravity measuring device for a crystallization tank, Fig. 2 is an explanatory diagram of a mother liquor specific gravity measuring device using an air purge method, and Fig. 8 is an explanatory diagram of the present invention. FIG. 4 is an explanatory diagram of the apparatus in one embodiment, and FIG. 4 is a chart recording of the measurement results of the embodiment. In the figure, 1... crystal tank, 2. ．． 2. ...Charging pipe, 8.
, 82... Impulse pipe, 4... Flow meter, 5... Supply pipe, 6... Differential pressure transmitter. Applicant Sumikin Chemical Co., Ltd. Figure 2 Figure 3

Claims (1)

[Claims] In the crystallization tank of the granular ammonium sulfate production process, a pressure pipe was connected to the charging pipe inserted from the tank wall at two locations at different depths from the surface of the ammonium sulfate mother liquor, a certain amount of water was flowed, and the water was connected to the pressure pipe. A method for measuring the specific gravity of ammonium sulfate mother liquor in a crystallization tank, characterized in that the specific gravity is converted from the difference in back pressure of the inflow water at the two locations using a differential pressure transmitter and the difference in depth.