JP2003320325A - Sludge discharge method for petroleum refining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently remove sludge bonded and deposited in a system in a short time while holding a petroleum refining apparatus to an unopened state without opening the same. <P>SOLUTION: A foaming agent is added to the interior of the system of the petroleum refining apparatus and residual sludge is efficiently discharged by generated air bubbles. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently discharging sludge adhering and depositing in a system of a petroleum refining apparatus to the outside of the system.

[0002]

2. Description of the Related Art Since dirt adheres to the inside of a petroleum refining system over time, chemical cleaning is performed to remove the dirt. However, when the chemical cleaning in the system of the oil refining apparatus is performed without opening, the stains that cannot be removed only by the chemical cleaning remain in the system as sludge. If the sludge residue does not hinder the operation of the equipment, the operation is restarted with the sludge remaining in the system.However, the sludge residue generally causes the local corrosion or the operation. Since it may cause early deterioration of the U value (overall heat transfer coefficient) and ΔP (differential pressure) after resumption, it is desirable to remove this.

Conventionally, the removal of sludge remaining in the system is
It is done by opening the device and cleaning it with high-pressure water, etc.
There is a drawback that the shutdown period becomes long.

[0004]

DISCLOSURE OF THE INVENTION The present invention is an oil refining apparatus capable of efficiently removing sludge adhering and depositing in a system in a short time without opening the oil refining apparatus. The purpose of the present invention is to provide a sludge discharge method.

[0005]

A sludge discharging method for an oil refining apparatus according to the present invention discharges sludge adhered and accumulated in the system of an oil refining apparatus to the outside of the system by adding a chemical to the system. The method is characterized in that the chemical comprises a foaming agent.

In the present invention, the bubbles generated in the system by adding the foaming agent adhere to the sludge deposited and accumulated in the system. The sludge to which the air bubbles are attached floats by the buoyancy of the air bubbles and is easily discharged to the outside of the system.

In the present invention, it is preferable to use a foaming agent and a foaming auxiliary together, and hydrogen peroxide or percarbonate can be used as the foaming agent.

Catalase or hydrazine can be used as a foaming aid. For example, by adding catalase, which is a hydrogen peroxide decomposing enzyme, to hydrogen peroxide, oxygen is generated by decomposition of hydrogen peroxide in the following reaction. Can be made.

[0009]

[Chemical 1]

If hydrazine is used, nitrogen can be generated by the following reaction.

[0011]

[Chemical 2]

Since such bubbles are also generated inside the sludge agglomerates accumulated in the system, the sludge agglomerates are collapsed by the generation of bubbles in the sludge agglomerates so that the sludge can be easily floated and flown out. You can Further, the flow velocity of the cleaning liquid is increased by the generation of bubbles, and the sludge discharging effect is further enhanced by increasing the flow velocity of the cleaning liquid.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a sludge discharging method for an oil refining apparatus of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of a sludge discharging method for an oil refining apparatus of the present invention. In FIG. 1, sludge in the heat exchangers 5 and 6 of the oil refining apparatus including the heating furnace 1, the vacuum flasher 2, the pumps 3 and 4, and the heat exchangers 5 and 6, particularly sludge in the heat exchangers 5 and 6 is likely to accumulate,
According to the method of the present invention, it is discharged out of the system by the following procedure.

First, as shown in FIG.
2, 16, 17, etc., the circulation pump 7, the circulation tank 8, and the sludge recovery device 9 are temporarily installed.

Supplying water into the system, the circulation tank 8,
Piping 11, circulation pump 7, piping 12, 13A, 13B,
Shell side of heat exchanger 5, tube side of heat exchanger 6, pipes 14A, 14B, shell side of heat exchanger 6, tube side of heat exchanger 5, pipes 15A, 15B, pipe 16, sludge recovery device 9, The cleaning system of the pipe 17 is filled with water.

Circulation of water in the cleaning system is started by the circulation pump 7. First, chemicals such as sodium hydroxide and a surfactant are added to the cleaning water to degrease and clean the system. After degreasing and cleaning, drain the cleaning water out of the system.

Next, water is supplied again to fill the inside of the cleaning system. Circulation is restarted by the circulation pump 7, and the foaming agent is added through the pipe 18 on the suction side of the circulation pump 7. For example, the 35 wt% hydrogen peroxide aqueous solution is injected at a constant flow rate and over a period of one cycle or more of the circulating water so that the injection amount is 35% by weight with respect to the total amount of water in the cleaning system.

After the injection of the foaming agent, the foaming auxiliary agent is injected from the pipe 19 to the discharge side of the circulation pump 7. As the foaming aid, for example, the foaming aid shown in Table 1 below is supplied at a constant flow rate so that the injection amount shown in Table 1 below is obtained with respect to the total amount of water in the cleaning system, and the circulating water is cycled once or more. Inject over time. In addition, since it is necessary to inject this foaming aid at a pressure higher than the discharge pressure of the circulation pump 7, a high-pressure pump such as a stroke pump is used.

After the completion of the injection of the foaming aid, the circulation treatment is preferably carried out for the time shown in Table 1 below. The circulation time shown in Table 1 corresponds to the foaming time (the time during which bubbles are generated) in the combination of the foaming agent and the foaming auxiliary.

[0021]

[Table 1]

The sludge discharged from the heat exchangers 5 and 6 during the circulation process is removed by the sludge recovery device 9 and discharged to the outside of the system, and is also separated in the circulation tank 8 by sedimentation.

After the above circulation treatment, the circulating liquid is discharged to the outside of the system, and then washed with at least 1 volume, preferably 2 to 3 volumes of water with respect to the amount of water in the cleaning system to perform the sludge discharge treatment. finish.

In the present invention, as the foaming agent, in addition to the above-mentioned hydrogen peroxide, sodium percarbonate (Na ₂ CO ₄ ),
It is also possible to use one or more percarbonates such as potassium percarbonate (K ₂ CO ₄ ). These percarbonates decompose in water to generate oxygen and become hydrogen carbonate.

The amount of these foaming agents added varies depending on whether or not a foaming aid is used in combination, but in consideration of the efficiency of bubble generation, economic efficiency, etc., the effective ingredient concentration in the cleaning system is 0.5 to 0.5.
It is preferably about 1.0% by weight.

As the foaming aid, hydrazine or catalase is preferably used, especially when hydrogen peroxide is used as the foaming agent. The amount of these foaming aids added is, for example, 0.05 to 0.1% by weight with respect to the total liquid amount for hydrazine, and 0.01 to 0.02 for hydrogen peroxide in the case of catalase. It is preferably set to wt%.

When a foaming aid is used in combination, it is preferable that the foaming aid is injected after the foaming agent has been injected, and then after the foaming agent has been sufficiently supplied to the entire system. In addition, hydrazine and catalase may be used in combination as the foaming agent, and for example, hydrazine may be injected and then catalase may be injected, or catalase may be injected and then hydrazine may be injected.

In FIG. 1, the foaming agent is injected into the suction side of the circulation pump, and the foaming auxiliary agent is injected into the discharge side of the circulation pump, for the following reason. That is, since the foaming agent does not foam by itself, it is preferable to inject it into the suction side of the circulation pump in order to uniformly mix it with water that is a solvent, and the foaming aid reacts with the foaming agent immediately after injection. ,
Since foaming occurs, it is preferable to inject into the discharge side of the circulation pump to prevent cavitation.

The circulation treatment time after the injection of the foaming agent or the foaming auxiliary agent varies depending on the capacity of the cleaning system, the amount of sludge, the foaming agent used, the type and the injection amount of the foaming auxiliary agent, and is generally 1 Approximately 2 hr is preferable, and in particular, in the combination of hydrogen peroxide and hydrazine and the combination of hydrogen peroxide and catalase, the circulation time shown in Table 1 is preferable.

[0030]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

Example 1 A simulated heat exchanger having the following specifications was manufactured at a scale of 1/6 of an actual heat exchanger, and a circulation loop shown in FIG. 2 (a) was assembled to carry out a sludge discharge experiment. As shown in FIG. 2 (a),
The water in the circulation tank 20 is sent to the simulated heat exchanger 22 by the pump 21, filtered by the strainer 23, and circulated. 24, 25 and 26 are valves, and 27 is a flow meter.

[Specification of simulated heat exchanger] Inner dimension of shell: 100 mm × 984 mmL (transparent PVC
Made) Bundle outer size: 100mmφ x 936mmL (SUS3
04) Tube: SUS φ6 mm × 200 mm (for 3 baffles) Tube arrangement: 6 or 7 tubes as shown in FIG. 2 (b)
Rows (3 rows only in the center)

The sludge accumulated in the shell of the actual heat exchanger was recovered and degreased in a beaker in advance. 1 kg of this sludge was put in the front part (introduction side of circulating water) in the shell of the simulated heat exchanger 22, and the sludge discharge experiment was conducted.

First, the tube 22A of the simulated heat exchanger 22
The flow velocity inside (the flow velocity of arrow F in FIG. 2B) is 0.1 m / s
The circulation of water was started to reach ec. 3 after the circulation starts
1 wt% (10,000 mg / Las 35% H ₂ O ₂ ) of a 5 wt% hydrogen peroxide aqueous solution was added to the amount of water in the system, and further 60% hydrated hydrazine aqueous solution was added to the amount of water in the system of 50 mg. / L (as 60% N ₂ H ₄ · H ₂ O). After 5 minutes have passed since there was no change in the sludge discharge condition in the simulated heat exchanger 22, the flow velocity was reduced to 0.
Circulation treatment was performed in increments of 05 m / sec, and the flow velocity was finally increased to 0.30 m / sec.

Table 2 shows the state of sludge discharge at each flow velocity and the circulation time required for complete sludge discharge.

Comparative Example 1 A sludge discharge experiment was conducted in the same manner as in Example 1 except that the aqueous hydrogen peroxide solution and hydrazine hydrate were not added. The circulation time was up to 1 hour when the flow velocity was increased to 0.30 m / sec.

As a result, the sludge discharge condition at each flow velocity is as shown in Table 2, and the flow velocity was 0.30 m / se.
The sludge discharge amount at the time of raising to c and circulating for 1 hour was 80%, and it was not possible to discharge the entire amount.

[0038]

[Table 2]

From Table 2, it is understood that according to the present invention, the sludge in the system can be completely discharged in a short time.

Examples 2 to 5 Simulated heat exchangers of the same scale as the actual one were manufactured, and 500 kL
A sludge discharge experiment was carried out by assembling the circulation loop shown in FIG. 3 using an engine pump of / hr. The simulated heat exchanger was manufactured with the following specifications, with a total length of up to 3 baffles.

[Specification of simulated heat exchanger] Shell: 1,200 mmφ × 2,000 mmL (made of carbon steel) Tube: O.D. D19 mmφ x 1,180 mm x 112
9

In FIG. 3, the water in the circulation tank 30 passes through a strainer 31 and a circulation pump (engine pump) 32.
Is introduced into the simulated heat exchanger 33 and returned to the circulation tank 30. Reference numeral 34 is a forward / reverse unit, which reverses the direction of the circulating water. That is, the circulating water is introduced by the forward / reverse unit 34 into the simulated heat exchanger 33 through the pipe 34A, and is discharged from the pipe 34B.
The flow direction introduced from 4B to the simulated heat exchanger 33 and discharged from the pipe 34A can be alternately set. Reference numeral 35 is a bypass pipe, 36 and 37 are valves, and 38 is a flow meter. Further, a pipe 41 provided with a chemical injection pump 39 and a valve 40 on the discharge side of the circulation pump 32.
More chemicals are injected.

In the simulated heat exchanger 33, the one recovered from the actual heat exchanger and degreased as in Example 1 was used, and 10 kg was put therein.

As the foaming agent, as in Example 1, 1.0% by weight of a 35 wt% hydrogen peroxide aqueous solution was added, and as the foaming aid, those shown in Table 3 were added at the concentrations shown in Table 3. The circulation treatment was performed at the circulation flow rate and the heat exchanger internal flow rate shown in Table 3.

In this circulation treatment, the inside of the simulated heat exchanger 33 was opened once every 30 minutes to check the internal condition, and the time required for complete discharge of sludge was examined.

As a result, as shown in Table 3, the time taken to complete the sludge discharge was smaller when catalase was used than when hydrazine was used as the foaming auxiliary under any flow rate condition. It was a short time. It is presumed that this is because the diameter of bubbles generated by catalase was larger, and the collapsing action of the sludge accumulation part was greater.

When catalase was used, air bleeding was frequently performed. Foaming in the system was completed in 2 hours when hydrazine was used and 1 hour when catalase was used.

[0048]

[Table 3]

Example 6 A sludge discharge process was carried out according to the present invention for a charge system and a bottom system having a large amount of dirt in a vacuum distillation apparatus of an actual facility. The circulation flow is as shown in FIG. In the sludge discharge treatment, an aromatic solvent was added to the light oil flushing, and then temporary equipment such as temporary piping was connected and both systems were circulated to perform degreasing cleaning, and then the results shown in Table 4 below. Sludge discharge treatment was performed under the conditions. After the first sludge discharge treatment, the water in the system was discharged and the second sludge discharge treatment was performed.

[0050]

[Table 4]

As a result, compared with the case where the sludge discharge treatment was not performed, both the oil content and the sludge were reduced on both the tube side and the shell side of the heat exchanger, and the finish was improved. In particular, the stain on the tube was almost completely removed. Further, even on the shell side, it was possible to pass through all the tubes, and there was little residual stain.

After the sludge discharge treatment, the heat exchanger was opened and the inside was inspected. As a result, it was found that the sludge inside the heat exchanger, which had been markedly deposited in the past, could be completely discharged to the outside of the system. confirmed.

[0053]

As described above in detail, according to the sludge discharging method of the petroleum refining apparatus of the present invention, sludge adhering and depositing in the system of the petroleum refining apparatus can be easily and efficiently operated by the open operation. Moreover, it can be discharged out of the system in a short time.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a sludge discharging method for an oil refining apparatus of the present invention.

2 (a) is a system diagram showing an experimental apparatus of Example 1, and FIG. 2 (b) is a schematic diagram showing a tube arrangement of a simulated heat exchanger.

FIG. 3 is a system diagram showing an experimental apparatus of Examples 2-5.

[Explanation of symbols]

1 heating furnace 2 vacuum flasher 3,4 pump 5,6 heat exchanger 7 Circulation pump 8 circulation tanks 9 Sludge recovery device 20 circulation tanks 22 Simulated heat exchanger 23 Strainer 30 circulation tanks 31 Strainer 33 Simulated heat exchanger 34 Forward / Reverse unit

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3B201 AA47 AB53 BB05 BB62 BB90                       BB95 CD22                 4H003 DA12 DA14 DC04 EA20 EB12                       EC01

Claims (4)

[Claims] 1. A method for discharging sludge adhering and accumulating in a system of a petroleum refining apparatus to the outside of the system by adding a chemical to the system, wherein the chemical contains a foaming agent. Sludge discharge method for refining equipment. 2. The sludge discharging method for a petroleum refining apparatus according to claim 1, wherein the chemicals include a foaming agent and a foaming auxiliary agent. 3. The sludge discharging method for a petroleum refining apparatus according to claim 1, wherein the foaming agent is hydrogen peroxide or percarbonate. 4. The sludge discharging method of a petroleum refining apparatus according to claim 2, wherein the foaming auxiliary agent is catalase or hydrazine.