Automatic pH control device for feeding dilute sulphuric acid in acidification lignin production process

Abstract

The utility model discloses an automatic pH control device for fed-batch dilute sulphuric acid in an acidification lignin production process, which comprises a dilute sulphuric acid fed-batch pipeline and a reaction kettle, one side of the surface of the dilute sulphuric acid fed-batch pipeline is provided with a corrosion-resistant electric adjusting ball valve, and the other side of the surface of the dilute sulphuric acid fed-batch pipeline is provided with a corrosion-resistant electromagnetic flowmeter. One end of the dilute sulfuric acid fed-batch pipeline penetrates through the inner wall of the reaction kettle and is fixedly communicated with an annular pipe, a dosing hole is formed in the surface of the annular pipe, and an online pH meter is fixedly mounted at the bottom of the inner wall of the reaction kettle. Through automatic program fed-batch, the product quality of each batch is stable, the carbonization phenomenon during sulfuric acid addition is reduced, the product quality is improved, the situation of excessive sulfuric acid fed-batch is also solved, production can be carried out in a relatively closed environment, and pollution is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of acid precipitation lignin, in particular to a pH automatic control device for adding dilute sulfuric acid in the production process of acid precipitation lignin. Background Art

[0002] Lignin is a complex class of organic polymers that forms an important structural material in the supporting tissues of vascular plants and some algae.

[0003] The existing acid-precipitated lignin production process is to add 8 cubic meters of ultra-membrane concentrated black liquor into a 10 cubic meter reactor, then use steam to heat and stir to about 92°C for full reaction, and then manually open the valve on the dilute sulfuric acid dosing pipe to add dilute sulfuric acid. Because the approximate addition amount is known, a large flow rate of 90% of the calculated amount is used in the early stage. At this time, the pH change is not large. When the NaOH in the black liquor is about to be consumed, a small flow rate of dilute sulfuric acid is added, and the pH will drop sharply. At the same time, the addition of sulfuric acid will produce H2S gas. However, the existing dilute sulfuric acid addition method in the acid-precipitated lignin production process has the following disadvantages:

[0004] (1) During the addition of dilute sulfuric acid at a low flow rate, manual observation is required to determine whether the pH value has reached the end point. Moreover, the addition process is manually controlled, and the carbonization reaction in the reactor is very serious, affecting the quality of the final product.

[0005] (2) The addition of sulfuric acid generates H2S gas, which has a significant impact on on-site operators, and some even require medical attention. Utility Model Content

[0006] The purpose of the utility model is to provide an automatic pH control device for adding dilute sulfuric acid during the acidification lignin production process, so as to solve the existing problems raised in the above background technology.

[0007] To achieve the above-mentioned purpose, the utility model provides the following technical solution: an automatic pH control device for adding dilute sulfuric acid during the acidification lignin production process, comprising a dilute sulfuric acid addition pipeline and a reactor, a corrosion-resistant electric regulating ball valve being installed on one side of the surface of the dilute sulfuric acid addition pipeline, a corrosion-resistant electromagnetic flowmeter being installed on the other side of the surface of the dilute sulfuric acid addition pipeline, one end of the dilute sulfuric acid addition pipeline passing through the inner wall of the reactor and fixedly connected to an annular tube, a plurality of dosing holes being opened on the surface of the annular tube, and an online pH meter being fixedly installed on the bottom of the inner wall of the reactor.

[0008] When the pH automatic control device for adding dilute sulfuric acid during the acid precipitation lignin production process of the present technical solution is used, the quality of each batch of products is stable through the automatic program of addition, the carbonization phenomenon when sulfuric acid is added is reduced, the product quality is improved, the production can be carried out in a relatively closed environment, and pollution is reduced.

[0009] As a preferred technical solution of the present invention, the corrosion-resistant electric regulating ball valve, corrosion-resistant electromagnetic flowmeter, and online pH meter are electrically connected to an external power supply via a PLC control system. The PLC control system automatically controls the opening and closing of the corrosion-resistant electric regulating ball valve based on flow rate and pH value.

[0010] As a preferred technical solution of the present invention, there are 500 dosing holes, which are evenly distributed on the surface of the annular tube. The 500 dosing holes distributed in an annular pattern make the spraying more uniform.

[0011] As a preferred technical solution of the present invention, the diameter of the dosing hole is 0.5 mm. The micropores are arranged so that the dilute sulfuric acid can be sprayed out in an atomized form.

[0012] As a preferred technical solution of the present invention, the annular tube is installed at the top of the inner wall of the reactor. The annular tube is arranged at an upper position in the reactor to facilitate the spraying of dilute sulfuric acid.

[0013] As a preferred technical solution of the present invention, the end of the dilute sulfuric acid feed pipeline away from the reactor is connected to the output end of an external dilute sulfuric acid pump, through which the dilute sulfuric acid is delivered.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. The control device enables safe flow addition of dilute sulfuric acid, which can be operated unmanned. The flow addition through the automatic program is highly repeatable, and the quality of each batch of products is stable. The carbonization phenomenon when adding sulfuric acid is reduced, and the product quality is improved. At the same time, the amount of sulfuric acid added is also reduced, and no or only a small amount of sulfuric acid participates in the carbonization reaction, which also solves the problem of excessive flow addition of sulfuric acid.

[0016] 2. This control device allows production to be carried out in a relatively closed environment, and the exhaust gas is passed into the exhaust gas treatment system, which reduces pollution and avoids the negative impact of H2S gas on the health of on-site operators. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of the utility model;

[0018] Figure 2 It is a top view of the annular pipe of the utility model.

[0019] In the figure: 1. Corrosion-resistant electric regulating ball valve; 2. Corrosion-resistant electromagnetic flowmeter; 3. Reactor; 4. Online pH meter; 5. PLC control system; 6. Dilute sulfuric acid feed pipeline; 7. Ring pipe; 8. Dosing hole. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] See also Figure 1-2 The utility model provides an automatic pH control device for adding dilute sulfuric acid during the acidification lignin production process, comprising a dilute sulfuric acid addition pipeline 6 and a reactor 3. A corrosion-resistant electric regulating ball valve 1 is installed on one side of the surface of the dilute sulfuric acid addition pipeline 6 to control the opening and closing of the pipeline. A corrosion-resistant electromagnetic flowmeter 2 is installed on the other side of the surface of the dilute sulfuric acid addition pipeline 6 to detect the flow of dilute sulfuric acid. One end of the dilute sulfuric acid addition pipeline 6 passes through the inner wall of the reactor 3 and is fixedly connected to an annular tube 7. A plurality of dosing holes 8 are opened on the surface of the annular tube 7. An online pH meter 4 is fixedly installed on the bottom of the inner wall of the reactor 3 to detect the pH value.

[0022] During use, the process of feed is to add a corrosion-resistant electric regulating ball valve 1 made of PP material to the main pipeline for the feed of dilute sulfuric acid, install a corrosion-resistant electromagnetic flowmeter 2 behind the valve, and then fix an online pH meter 4 in the reactor 3. Then, the signals of the electric valve, flowmeter and pH meter are led to the control system. The control system consists of a PLC and a touch screen, and then an automatic control program is written into the PLC. The valve opening is controlled by the readings of pH and flowmeter, thereby controlling the flow rate of dilute sulfuric acid and ensuring the stability of the feed.

[0023] The corrosion-resistant electric regulating ball valve 1, the corrosion-resistant electromagnetic flowmeter 2 and the online pH meter 4 are electrically connected to an external power supply through a PLC control system 5 to control operation. The end of the dilute sulfuric acid feed pipeline 6 away from the reactor 3 is connected to the output end of an external dilute sulfuric acid pump for conveying dilute sulfuric acid.

[0024] During use, dilute sulfuric acid is transported into the pipeline through an external dilute sulfuric acid pump, and the online pH is measured and fed back to the PLC. The PLC automatically controls the acid addition time and amount. The acid addition amount is calculated by the cumulative flow and instantaneous flow fed back by the corrosion-resistant electromagnetic flowmeter 2. The acid addition speed and total acid addition amount within a certain pH range are set in the automatic program. The real-time data is fed back by the corrosion-resistant electromagnetic flowmeter 2, and the PLC gives a signal to the corrosion-resistant electric regulating ball valve 1 to continuously adjust the valve opening, thereby realizing the curve flow addition of dilute sulfuric acid.

[0025] There are five hundred dosing holes 8 evenly distributed on the surface of the annular tube 7. The diameter of the dosing holes 8 is 0.5 mm. The annular tube 7 is installed on the top of the inner wall of the reactor 3 to facilitate the spraying of dilute sulfuric acid.

[0026] During use, the dilute sulfuric acid flow addition pipeline 6 is modified to surround the upper end of the reactor 3, and then 500 small holes with a diameter of 0.5 mm are punched in this circle of pipeline. When the dilute sulfuric acid is added, it will be added to the black liquor in the form of mist. The local reaction will be much milder and the reaction will be very uniform. No local violent reaction will occur. At the same time, the carbonization situation will be greatly reduced, thereby improving the quality of the final product.

[0027] When used specifically, the pH automatic control device for adding dilute sulfuric acid during the acidification lignin production process of the present invention adopts automated feeding equipment to achieve unmanned operation, and the feeding process is achieved through experimental simulation of gentle feeding. The feeding process is to add a corrosion-resistant electric regulating ball valve 1 made of PP material to the main pipeline for adding dilute sulfuric acid, install a corrosion-resistant electromagnetic flowmeter 2 behind the valve, and then fix an online pH meter 4 in the reactor 3, and then lead the signals of the electric valve, flowmeter and pH meter to the control system. The control system consists of a PLC and a touch screen, and then write an automatic control program in the PLC, and control the valve opening by the readings of pH and flowmeter, thereby controlling the flow addition amount of dilute sulfuric acid and ensuring the stability of the feeding. At the same time, the dilute sulfuric acid feeding pipeline 6 is modified around There is a circle on the top of the reactor 3, and then five hundred small holes with a diameter of 0.5mm are punched on this circle of pipes. When the dilute sulfuric acid is added, it will be added to the black liquor in the form of mist. The local reaction will be much milder and the reaction will be very uniform. There will be no local violent reaction. At the same time, the carbonization situation will be greatly reduced, which improves the quality of the final product. By measuring the online pH and feeding it back to the PLC, the PLC automatically controls the acid addition time and acid addition amount. The acid addition amount is calculated by the cumulative flow and instantaneous flow fed back by the corrosion-resistant electromagnetic flowmeter 2. The acid addition speed and total acid addition amount within a certain pH range are set in the automatic program. The real-time data is fed back by the corrosion-resistant electromagnetic flowmeter 2, and the PLC gives a signal to the corrosion-resistant electric regulating ball valve 1 to continuously adjust the valve opening, thereby realizing the curve flow addition of dilute sulfuric acid. These adjustments and feedback are immediate.

[0028] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pH automatic control device for adding dilute sulfuric acid during the acid precipitation lignin production process, comprising a dilute sulfuric acid addition pipeline (6) and a reactor (3), characterized in that: A corrosion-resistant electric regulating ball valve (1) is installed on one side of the surface of the dilute sulfuric acid flow-addition pipeline (6), and a corrosion-resistant electromagnetic flowmeter (2) is installed on the other side of the surface of the dilute sulfuric acid flow-addition pipeline (6). One end of the dilute sulfuric acid flow-addition pipeline (6) passes through the inner wall of the reactor (3) and is fixedly connected to an annular tube (7). A plurality of dosing holes (8) are opened on the surface of the annular tube (7), and an online pH meter (4) is fixedly installed on the bottom of the inner wall of the reactor (3).

2. The pH automatic control device for adding dilute sulfuric acid during the acidification lignin production process according to claim 1, characterized in that: The corrosion-resistant electric regulating ball valve (1), the corrosion-resistant electromagnetic flowmeter (2) and the online pH meter (4) are electrically connected to an external power supply via a PLC control system (5).

3. The pH automatic control device for adding dilute sulfuric acid during the acidification lignin production process according to claim 1, characterized in that: There are five hundred dosing holes (8) uniformly distributed on the surface of the annular tube (7).

4. The automatic pH control device for adding dilute sulfuric acid during the acidification lignin production process according to claim 3, characterized in that: The diameter of the dosing hole (8) is 0.5 mm.

5. The automatic pH control device for adding dilute sulfuric acid during the acidification lignin production process according to claim 1, characterized in that: The annular tube (7) is installed on the top of the inner wall of the reactor (3).

6. The automatic pH control device for adding dilute sulfuric acid during the acidification lignin production process according to claim 1, characterized in that: One end of the dilute sulfuric acid feed pipeline (6) away from the reactor (3) is connected to the output end of an external dilute sulfuric acid pump.

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