JPS58130103A - Supplying method of reducing agent to reducing tower - Google Patents

Abstract

PURPOSE:To optimize the supply of reducing agents by controlling the rate of supplying of the reducing agents by the product of the flow rate of the SO2- contg. gas to be supplied into a reducing tower and the concn. of SO2 therein and the product of the concn. of O2 in the gas to be supplied to the reducing tower and the quantity of the air to be added. CONSTITUTION:An SO2-contg. gas is fed through a main pipeline 8 into a reducing tower 2 and is discharged as H2S into a main pipeline 9. The data calculated by reaction formulas is beforehand put into a control box 12, and the concn. of SO2 in the gas to be supplied into the tower 2 is measured with a measuring instrument 19 and is fed to the box 12. The concn. of O2 is measured with a measuring instrument 16 and is fed to the box 12. The amt. of the SO2 to be supplied is known from the product of the measured value of a gas flowmeter 8b and the concn. of SO2 and for the air to be added, the amt. of the O2 to be supplied is determined by the product of the measured value of a flowmeter 15 and the concn. of O2. Thus, the rate of supplying the reducing agents is determined, and the rate of discharging the reducing agents from a hopper 20 is determined, whereby the rate of supply of the reducing agents with good efficiency into the tower 2 is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reducing agent supply method for suitably supplying a reducing agent to a reduction tower, which is one of the devices constituting a sulfur recovery plant, to save the reducing agent.

One method for removing sulfur from combustion exhaust gas is to adsorb and remove the sulfur from flue gas using an adsorbent.When implementing this method, the adsorbed sulfur is desorbed and the adsorbent is regenerated. It is common practice to separate and recover elemental sulfur (S) from the desorbed sulfur-containing gas to improve economic efficiency.

FIG. 1 shows a conventional dry method for removing and recovering sulfur. In the figure, the desorbed sulfur component flows into the reduction tower 2 together with the gas containing it as S02. In the reduction tower 2, a part of the S02 supplied into the tower is converted into single S as shown in the following equation.
becomes.

C+802--8+002 (1) However, most of 802 undergoes the process shown in formula (2)t (3) and becomes H2S in order to undergo a Claus reaction in a reactor placed downstream of the reduction tower.

a + H20→H2+ Co...(
2) H2,+ SO2 → H2S+ 02...
(3) The reaction gas that has exited the reduction tower 2 undergoes removal of dust in a precipitator 3, and the gas from which dust has been removed is cooled to a predetermined temperature in a condenser 4.
is precipitated and recovered. The reaction gas from which S has been recovered further flows into the Claus reactor 5, where a simple substance S is produced according to the following equations (4) and (5), and S is recovered.

H2S + 1-202--u 2 o + s O2
...(4) 2H2S +5o2-4-38 + 2H
20. (5) In this case, 1. SO2 is generated from the H2S supplied from the reduction tower 2 as shown in formula (4), and then this SO2 and unreacted H2S are reacted as shown in formula (5). Since S is recovered by the reaction, SO2 may be insufficient depending on the state of the reaction, and S may not be recovered sufficiently according to equation (5). Here, the reaction of formula (4) is performed by combining a part of H2S with air (02) supplied through the air supply pipe 5a.
02, and the S recovery is insufficient.
This is because the amount of O2 generated is unstable. In other words, the formula (5
This is due to the fact that it is not possible to maintain an appropriate molar ratio in ), that is, a ratio of 1 for SO2 to 2 for H, 2S.

For this reason, the inventors first installed a pipe 7 that bypasses the reduction tower shown by the dashed line in FIG. A patent application was filed in 1973 requesting an invention for properly carrying out the
No. 6-91610) This problem was solved.

The purpose of this invention is to propose a method for supplying a reducing agent that reduces operating costs by using an appropriate amount of an oxidizing agent, which also serves as a consumable material, in order to operate the sulfur recovery plant more efficiently.

In short, this invention provides a method for supplying a reducing agent to a reduction tower of a sulfur recovery device. This method is characterized in that the product of the amount of added air is sent as a signal to a control box which stores and issues a command signal to control the amount of reducing agent supplied to the reducing tower.

The present invention will be explained below with reference to the accompanying drawings.

FIG. 2 is a drawing showing a control system for equipment of a reduction tower and pipes connected thereto according to the present invention. Reference numeral 8 is a main pipe line for the SO2 component-containing gas sent out from the desorption tower 1. A gas analyzer 19 for 802 gas is provided in this main pipe. The bypass line 7 branches from this main line 8 at a branch point 10 and connects to the main line 9 for the gas sent out from the reduction tower 2. The main line 8 is provided with a gas flow control valve 8a' and a gas flow meter 8b, and the bypass line 7 is provided with a bypass gas flow control valve 7a and a gas flow meter 7b. H2 sent to the main pipe line 9 by these two flow control valves
S and the SO2-containing gas supplied from the bypass pipe are mixed in the main pipe 9 at a ratio of 2 parts H2S to 1 part SO2, so that a suitable separation of S and S precipitation reaction in the Claus reactor can take place. can do.

The reducing agent whose main component is carbon (0) is contained in the reducing agent hopper 20.
The required amount is supplied into the reduction tower by a supply amount control device 21 such as a rotary feeder.

The level of the reducing agent in the tower is determined by the signals from the upper limit level meter 11a and the lower limit level meter 11b.
The reducing agent is sent via the Low Lim1ttJ LLC to the control box 12 which issues storage and control commands, and the extraction of the reducing agent that controls the rotary feeders 21 and 22 is controlled by the extraction amount of the rotary feeder etc. attached to the bottom of the reduction tower 2. The reducing agent extracted by the device 22 is separated into fine powder, cooled, and then incinerated in the incinerator.

The pipe line 8t is provided with a gas flow rate control valve 8 and a flowmeter 8b, and an additional air supply pipe 13 is connected downstream of the flowmeter 8b to control the temperature inside the reduction tower 2. →C0
2) Involved in the reaction. This additional air supply pipe 13 has an air flow control valve 14. and an air flow meter 15 are provided, and an air flow signal is sent to the control box 12.

0 downstream of the connection point between this additional air supply pipe 13 and the main pipe 8.
Two measuring instruments 16 are provided, and their o2 quantity signals are sent to the control box 12.

A gas analyzer 17 is provided near the outlet nozzle of the reduction tower 2 in the main pipe line 9 for the gas sent out from the reduction tower 2, and the 002 concentration signal is sent to the control box 12.

The temperature inside the reduction column 2 is measured by a thermometer 18, and the temperature signal is sent to the control box 12.

Here, C and S02, which are the main components of the reducing agent in the reduction tower,
Let us consider the reaction with S and the reaction that precipitates simple S.

0-8. complex +E302 002+Snog
) - (8) (Active point) According to experiments, when the utilization rate of C is low, that is, when there is a large amount of C relative to so2, the reaction up to equation (7) is completed, and the reducing agent is O-S cnmpl of the whale. It will be discharged in this condition. Therefore, if this waste reducing agent is incinerated in a boiler or the like, 802 will be regenerated and it will be necessary to dispose of it, which is an inconvenience. The utilization rate of C must be at least above a certain value, and on the other hand, the supply of C in excess of what is necessary will also harden due to the re-occurrence of SO2, so it must be eliminated.

On the other hand, other reactions occurring within the reduction tower include the following, and the amount of C consumed can be calculated.

C+02--CO2...(9) The reaction in (9) can be calculated based on the amount of air added.

0-1- H2O-m-001H2... (10) This reaction is a water gas reaction. The amount of H2O is determined by the concentration of H2SO4 generated in the adsorption tower (not shown; a tower that processes SO2 gas contained in boiler exhaust gas, etc.).
The reaction rate of the reaction of formula (lO) can be determined by the temperature inside the reduction column 2.

An example of the results measured at the pilot plant is shown below.

Example: When the gas temperature at the inlet of the reduction tower is 130°C and the moisture content is 7%, the H2SO4 concentration is 80%. (HS
o ・1.36H20) Therefore, the amount of 4 H2O is 2.36 times the amount of 802.

From the above explanation, the amount of reducing agent consumed in the reducing tower 2 changes depending on the sog amount at the inlet of the reducing tower, as is clear from equation (6), and equation (9) y ('o)
As is clear from the formula, it depends on the amount of <o2. Therefore, if the data calculated by the chemical reaction formula considering the operating conditions is stored in the control box 12, the SO2 concentration in the gas supplied to the reduction tower is measured by the gas measuring device 19 and sent as a signal to the control box 12. If you measure 04 degrees with the 02 measuring device 16 and send the signal to the control box 12, the gas flow meter 8
The amount of S02 supplied decreases by the product of b and the S O2 concentration,
Added air is supplied by the product of flowmeter 15 and 04 degrees.
The amount is determined. This determines the amount of reducing agent supplied, and therefore the amount of reducing agent extracted.

In addition to this, the temperature inside the reduction tower 2 is measured by the temperature measuring device 18 and a temperature signal is sent to the control box 12, and the signal from the gas measuring device 17 which measures the ao2 concentration in the main pipe line 9 at the outlet of the reduction tower 2 is sent. When the signals are sent to the control box 12 and used as correction signals, a more desirable reducing agent consumption situation can be grasped, and an appropriate amount of reducing agent can be supplied to the reduction tower.

By implementing this invention, it is possible to grasp the degree of consumption of the reducing agent and determine the most efficient supply rate of the reducing agent to the reduction tower, thereby avoiding wasteful consumption of the reducing agent during operation of the sulfur recovery plant. plant operation efficiency can be increased.

[Brief explanation of the drawing]

FIG. 1 is a pipe system diagram of a dry sulfur recovery apparatus, and FIG. 2 is a diagram showing a wiring diagram of a reducing tower, particularly a device for controlling supply of reducing agent, according to the present invention. 1... Desorption tower 2... Reduction tower 8, 8', 9... Main pipe line 7... Bypass pipe line 8 a'... ...Gas flow control valve 11a ...Upper limit level meter 11b ...Lower limit level meter 12 ...Control box 13 ...Additional air supply pipe 16... ...O1 measuring instrument 17...Gas analyzer (CO2) 18...
・Temperature measuring device 19... Gas analyzer (S02) 20...
・Reducing agent hopper

Claims (1)

[Claims] 1. Supplying a reducing agent to a reduction tower of a sulfur recovery device 3.
In the ゜method, the product of the flow rate of the SO2-containing gas supplied to the reduction tower and its SO2 concentration, and the product of the zero-voice degree in the gas supplied to the reduction tower and the amount of added air are stored and commanded as signals respectively. A method for supplying reducing agent to a reducing tower, characterized in that the amount of reducing agent supplied to the reducing tower is controlled by a control box that sends a signal. 2. A device is provided to supply almost the same amount of reducing agent to the reducing tower as the reducing agent extracted from the reducing tower, the reducing agent is extracted, and the reducing agent level in the reducing tower is sent as a correction signal to the control box. A method for supplying a reducing agent to a reduction tower according to claim 1. 3. Claims 1 or 2, characterized in that the Co2 concentration signal from the temperature measuring device that measures the temperature inside the reduction tower is sent to the control box as a correction signal.
A method for supplying a reducing agent to a reduction tower as described in Section 1.