CN101738133B - Optimized operation method of circulating cooling water system - Google Patents

Abstract

The optimized operation method of the circulating cooling water system comprises the following steps: the circulating cooling water system of the power generation device operates at a low concentration multiple, sewage discharged by the power generation device is used as water supplement of the chemical circulating cooling water system, the circulating cooling water system of the chemical system operates at a higher concentration multiple, water discharged by the chemical system is used as water supplement of the oil refining circulating water system, the circulating cooling water system of the oil refining device operates at the highest concentration multiple, and the discharged water of the system is directly discharged outside. When the three circulating cooling water systems of power generation, chemical engineering and oil refining are operated by adopting the method, the total water supplement amount and the total medicament amount are not more than the total water supplement amount and the total medicament amount of the three circulating cooling water systems which are independently operated, only the circulating water system of oil refining has higher concentration multiple, poorer water quality and higher treatment difficulty, and the two circulating water systems of power generation and chemical engineering have lower concentration multiple, better water quality and easier treatment, thereby ensuring the optimal effect of the water treatment medicament.

Description

Optimal Operation Method of Circulating Cooling Water System

technical field

The invention relates to a processing method for optimizing operation of three circulating cooling water systems respectively providing circulating cooling water for power generation, oil refining and chemical plants, and belongs to the field of circulating cooling water treatment technology.

Background technique

Cooling water is an indispensable public works for industrial enterprises, and it is a large water user. Recycling the cooling water after treatment, on the one hand, can meet the requirements of the process for water treatment effect and ensure the long-term normal operation of the production device; on the other hand, it can save more than 98% of industrial water, reduce a larger amount of sewage, and protect water resources. , protect the water environment, and reduce production costs have huge benefits.

At present, large-scale comprehensive enterprises contain multiple sets of production equipment such as oil refining, chemical industry, and power generation. Therefore, the enterprise has multiple circulating cooling water systems to provide circulating cooling water for oil refining, chemical industry, and power generation equipment. The open circulating cooling water system is the most widely used one in the process of power generation. The heat obtained by the cooling water from the heat exchanger is directly dissipated to the atmosphere in the cooling tower or other equipment, that is, it is cooled under the condition that the water is in contact with the air, and then returns to the heat exchanger to repeat the process of transferring heat. The main equipment in the circulating water system are cooling towers, circulating water pumps and heat exchangers. At present, cooling towers are mainly designed as hyperbolic natural draft cooling towers. Most heat exchangers are condensers, the outer wall is in contact with high-velocity steam and condensed water, and the inner wall is in contact with cooling water. Due to its large heat exchange capacity, the condenser is mostly made of copper alloy and titanium alloy. The circulating cooling water of the power generation unit has stable water quality, and there is no leakage of other substances.

The petrochemical industry is an industrial system that uses crude oil as a resource to produce chemical products. It is an important part of the energy and raw material industry and a pillar industry of my country's industry. The petrochemical industry takes ethylene plant as the leader, and its downstream includes chemical fiber, polyolefin, chemical raw material, large chemical fertilizer, rubber and other plants. The production characteristics of petrochemical production facilities are: (1) large-scale production and many equipments, especially high-temperature and high-pressure equipment; (2) raw materials and products are flammable and explosive; (3) complete sets of technologies have become the mainstream of technological development; (4) ) There are many auxiliary industries supporting petrochemical industry, such as power, computer, air separation unit, etc.; (5) The three major synthetic materials have a large volume and demand. According to the characteristics of petrochemical equipment, the water coolers of the equipment are mostly floating head type and fixed tube plate type, and the material also varies according to the heat exchange medium. Most of them are stainless steel and copper alloy, and a few are carbon steel. Since heat exchange equipment is mostly made of stainless steel and copper alloy, the main problem in the circulating water system is scaling, not corrosion, and it is not easy to cause corrosion and perforation of equipment to cause leakage of heat exchange medium. In addition, most of the heat exchange media are chemical raw materials and low-carbon hydrocarbons. Leakage only causes changes in the pH value of the circulating water, which has little impact on the water quality of the circulating cooling water, and the water quality is relatively stable.

Petroleum refining equipment includes atmospheric and vacuum, gas splitting, catalytic cracking, catalytic reforming, hydrocracking, delayed coking and other devices. The petroleum refining industry uses crude oil as raw material to produce light oil with high octane number after processing products and chemical raw materials. There are a large number of water coolers in refineries, most of which are made of carbon steel. The heat exchange medium is mostly organic substances such as oil. If the heat exchange medium leaks, the circulating water will contain oil substances, which will bring a lot of harm to the water quality control. For example, due to the extremely poor thermal conductivity of the oil film, adhesion to the pipe wall will affect the heat transfer effect, and will prevent the contact between the corrosion inhibitor and the metal surface, so that the protective film cannot be formed or the protective film is incomplete, resulting in localized corrosion. Oil is the nutrient source for microorganisms. Because the existence of oil will increase the activity of microorganisms, anaerobic sulfate-reducing bacteria can multiply rapidly under the oil pollution and form oily black slime. Therefore, the water quality of the circulating cooling water of the petroleum refining unit is the most difficult to control, and the composition of the water is the most complex.

At present, the enterprise adopts an independent treatment operation mode for these circulating water systems to meet the operation of each production device, that is, each circulating water system independently replenishes water, discharges sewage independently, and operates independently at a certain concentration multiple. In order to achieve water-saving goals, enterprises often control all circulating water systems to operate at a higher concentration multiple, resulting in poor water quality in all circulating water systems, resulting in increased difficulty in circulating water treatment, and treatment effects are difficult to guarantee.

Contents of the invention

The purpose of the present invention is to propose an optimized operation method that is beneficial to ensure the treatment effect of the circulating cooling water systems of the three devices for enterprises that have circulating cooling water systems that respectively provide circulating cooling water for power generation, oil refining and chemical plants.

The optimized operation method of the circulating cooling water system proposed by the present invention includes: the circulating cooling water system of the power generation device is operated at a low concentration ratio, its sewage is used as replenishment water for the circulating cooling water system of the chemical plant, and the circulating cooling water system of the chemical plant is at a higher It operates at the concentration multiple, and its drainage is used as replenishment water for the circulating cooling water system of the refining unit. The circulating cooling water system of the refining unit operates at the highest concentration multiple, and the drainage of the circulating cooling water system of the refining unit is directly discharged.

The concentration ratio of the circulating cooling water system of power generation, chemical and oil refining units n _power generation, n _{chemical industry} and n _{oil refining} meet the following conditions: M ₁ ≤ n _{power generation} < M ₂ ≤ n _{chemical industry} < n _{oil refining} , where n _{oil refining} is the circulating cooling of oil refining units When the water system operates independently, the concentration multiples, M ₁ and M ₂ are calculated according to the following formula:

In formulas (1) and (2), E _{power generation} , E _{chemical industry} , and E _{oil refinery} are the evaporated water volumes of the three circulating cooling water systems of power generation, chemical and oil refining units, respectively, in m ³ /h. The evaporation water of the circulating cooling water system of the three devices can be calculated according to the following formula:

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}{\mathrm{<span\; class="notranslate">\; 580</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In formula (3), R represents the amount of circulating water, in m ³ /h; Δt represents the temperature difference between outlet and inlet (the difference between outlet water temperature and inlet water temperature), in ℃.

When the concentration multiples n of the circulating cooling water systems of power _generation and _{chemical plants} are equal to M ₁ and M ₂ respectively, after the circulating cooling water systems of oil refining plants reach the concentration multiples, it is only necessary to add water to the circulating cooling water systems of power generation plants Treatment of chemicals, the circulating cooling water system of chemical and oil refining equipment does not need to add water treatment chemicals, and the drainage of the circulating cooling water system of power generation and chemical equipment does not need to be purified, and the drainage of the circulating cooling water system of power generation equipment is used as circulating cooling water of chemical equipment The water supply of the system, the drainage of the circulating cooling water system of the chemical plant is used as the supplementary water of the circulating cooling water system of the refinery plant.

When the concentration multiples n power generation and n chemical industry circulating cooling water systems of power _generation and _{chemical plant} are greater than M ₁ and M ₂ respectively, after the circulating cooling water system of oil refining unit reaches the concentration multiple, the three circulating cooling water systems of power generation, chemical and oil refining Water treatment chemicals need to be added to ensure the concentration of water treatment chemicals used in the circulating cooling water systems of the three devices to meet the normal operation of the circulating cooling water systems of the three devices.

Said water treatment agent can be a corrosion and scale inhibition composite agent with corrosion and scale inhibition effects, preferably organic phosphonate, phosphine carboxylate, zinc salt and multi-polymers containing acrylic acid-2-acrylamide group one or more of .

The present invention has the following characteristics:

a. adopting the operating method of the present invention ensures the best effect of the water treatment agent in the circulating cooling water system of the three devices.

b. When the three circulating cooling water systems of power generation, chemical industry and oil refining equipment are operated by the method of the present invention, the total amount of replenishment water and the total amount of water treatment agents are no more than the total amount of replenishment water and the total amount of water replenishment of the independent operation of the circulating cooling water systems of the three devices. The total amount of treatment agent.

Detailed ways

The present invention will be further described below by way of examples, but the present invention is not limited thereto.

Example 1

The water quality of the experiment was supplemented by the circulating water system of a petrochemical company in Zhongyuan. The multiple can reach up to about 6.0. The data in the table shows that the on-site water is high-hardness and high-salt water, which is of strong scaling quality.

Table 1 Main data of experimental water quality

The dynamic simulation experiment is carried out according to the 407 method in the "Cooling Water Analysis and Experimental Methods" of China Petroleum and Chemical Corporation. The circulating water volume of the system is 150L/h, and the temperature difference between the inlet and outlet water is 10°C. The on-site water was used as supplementary water for dynamic simulation experiments after the alkalinity was adjusted with sulfuric acid. The test tube is not pre-filmed, the water flow rate in the test tube is controlled at 0.8m/s, the inlet water temperature is controlled at 32°C, the outlet water temperature is controlled at 40°C-42°C, the concentration ratio is controlled at 6.0±0.2, and the use of composite water treatment agents in the system The concentration is 100mg/L.

For the dynamic simulation test system, the evaporation of the system can be calculated according to the formula (3) according to the circulating water volume of the system and the temperature difference between the inlet and outlet water.

E＝(150×10)/580＝2.6L/h

Since the circulating water volume of the dynamic simulation test device system and the temperature difference between the inlet and outlet water are the same,

E _{power generation} = E _{chemical industry} = E _{oil refining} = 2.6L/h

Three circulating water systems operate according to the method of the present invention, and the oil refining circulating water system controls the concentration factor to be 6.0 ± 0.2, and the use concentration of the composite water treatment agent is 100mg/L, calculated as follows according to formula (1) and formula (2):

M ₁ =[(6.0-1)/3]+1=2.7

M ₂ =[(6.0-1)×2/3]+1=4.3

The concentration multiple control range of the power generation circulating water system: 2.7≤n _{power generation} <6, the concentration multiple control range of the chemical circulating water system: 4.3≤nchemical _industry <6. When the concentration factor of the power generation circulating water system is 3.0±0.2, the concentration factor of the chemical industry circulating water system is 4.5±0.2, and the concentration factor of the oil refining circulating water system is controlled at 6.0±0.2, the results of the 15-day dynamic simulation experiment are shown in Table 2. The results in Table 2 show that the treatment effect of the power generation and chemical system operating at a lower concentration ratio is better than that of the oil refining system operating at a high concentration ratio.

Table 2 Dynamic simulation experiment results

Example 2

Experiment water quality and test condition are with embodiment 1,

According to the calculation of Example 1, the control range of the concentration multiple of the power generation circulating water system: 2.7≤npower _generation <6, and the concentration multiple control range of the chemical industry circulating water system: 4.3≤nchemical _industry <6. When the concentration factor of the power generation circulating water system is 3.5±0.2, the concentration factor of the chemical industry circulating water system is 5.0±0.2, and the concentration factor of the refinery circulating water system is controlled at 6.0±0.2, the results of the 15-day dynamic simulation experiment are shown in Table 3. The results in Table 3 show that the treatment effect of the power generation and chemical system operating at a lower concentration ratio is better than that of the oil refining system operating at a high concentration ratio.

Table 3 Dynamic simulation experiment results

Example 3

Experiment water quality and test condition are with embodiment 1,

According to the calculation of Example 1, the control range of the concentration multiple of the power generation circulating water system: 2.7≤npower _generation <6, and the concentration multiple control range of the chemical industry circulating water system: 4.3≤nchemical _industry <6. The concentration multiple of the power generation circulating water system is 2.7±0.2, the concentration multiple of the chemical circulating water system is 4.3±0.2, and the concentration multiple of the oil refining circulating water system is controlled at 6.0±0.2. After the three systems of power generation, chemical industry and oil refining reach the concentration multiple , the discharge volume of the three systems is the same, only need to supplement the water treatment agent in the power generation system to meet the concentration of chemicals used in the chemical and oil refining circulating water system, the other two systems do not need to add water treatment agent, easy to operate. The results of the 15-day dynamic simulation experiment are shown in Table 4. The results in Table 4 show that the treatment effect of the power generation and chemical system operating at a lower concentration ratio is significantly better than that of the oil refining system at a high concentration ratio.

Table 4 Dynamic simulation experiment results

Claims (5)

1. the Optimum Operating Method of recirculating cooling water system, comprising: the recirculating cooling water system of TRT moves at low cycles of concentration, and its sewer is as the moisturizing of chemical plant installations recirculating cooling water system; The recirculating cooling water system of chemical plant installations moves under higher cycles of concentration, and its draining is as the moisturizing of oil refining apparatus recirculating cooling water system; The recirculating cooling water system of oil refining apparatus moves under the highest cycles of concentration, and its draining directly effluxes.

2. according to the described method of claim 1, it is characterized in that the cycles of concentration n of the recirculating cooling water system of generating, chemical industry and oil refining apparatus _Generating, n _{Chemical industry}And n _{Oil refining}Meet the following conditions: M ₁≤n _Generating＜M ₂≤n _{Chemical industry}＜n _{Oil refining}, wherein, n _{Oil refining}Cycles of concentration when being oil refining apparatus recirculating cooling water system independent operating, M ₁, M ₂According to computes:

In formula (1) and (2), E _Generating, E _{Chemical industry}And E _{Oil refining}Be respectively the evaporated water of generating, chemical industry and three recirculating cooling water systems of oil refining apparatus, the m of unit ³/ h; The evaporated water of generating, chemical industry and three recirculating cooling water systems of oil refining apparatus is according to according to computes:

$E=\frac{R\&times;\mathrm{\&Delta;t}}{580}---\left(3\right)$

In the formula (3), R representes quantity of circulating water, the m of unit ³/ h; Δ t expresses the difference that the saliva temperature deducts the inlet water temperature degree, unit ℃.

3. according to the described method of claim 2, it is characterized in that, when the cycles of concentration of recirculating cooling water system of generating, chemical plant installations equals M respectively ₁, M ₂The time; After the recirculating cooling water system of oil refining apparatus reaches cycles of concentration; Only need to add water treatment agent at the TRT recirculating cooling water system; Chemical industry and oil refining apparatus recirculating cooling water system need not add water treatment agent again; And the draining of generating and chemical plant installations recirculating cooling water system need not carry out purified treatment, and the draining of TRT recirculating cooling water system is as the moisturizing of chemical plant installations recirculating cooling water system, and the draining of chemical plant installations recirculating cooling water system is as the moisturizing of oil refining apparatus recirculating cooling water system.

4. according to the described method of claim 2, it is characterized in that, when generating and the cycles of concentration of chemical plant installations recirculating cooling water system respectively greater than M ₁, M ₂The time; After the oil refining apparatus recirculating cooling water system reaches cycles of concentration; Generating, chemical industry and three recirculating cooling water systems of oil refining apparatus all need be added water treatment agent; Guarantee three water treatment agent working concentrations in the device recirculating cooling water system, satisfy the normal operation of three device recirculating cooling water systems.

5. according to claim 3 or 4 described methods, it is characterized in that said water treatment agent is selected from organic phosphonate, phosphine carboxylate, zinc salt and contains in the multiple copolymer of acrylic acid-2-acrylamido one or more.