JP7380747B2 - Method for improving productivity of production process with heat exchange process - Google Patents

Description

The present invention relates to a method for improving the productivity of a production process including a heat exchange process using steam.

During the production process, heating with steam or hot water and cooling with cold water, air, etc. are common in industrial manufacturing processes.

For example, in reaction vessels for chemical synthesis, polymerization is accelerated by a heating process using steam or hot water, and when the reaction is stopped, cold water or a refrigerant is introduced for rapid cooling. ing.

This production process is generally performed alternately and repeated for each production batch, so the longer the temperature rise time at the start, the longer the heating process becomes, which lengthens the production time and reduces productivity.

Even for a single product, multiple manufacturing processes are often combined, and a delay in the manufacturing time of one process often affects the entire process.

Reasons for the longer heating time include the presence of air in the heat exchanger during cold start-up, the obstruction of heat exchange due to the accumulation of initial condensate, and the fact that the originally limited capacity of the heat exchanger becomes rate-limiting. Examples include cases where it takes time to raise the temperature.

On the other hand, if the heat exchanger itself is made of carbon steel, etc., if the inner surface corrodes due to the quality of the industrial water or the steam properties, heat transfer may be inhibited by metal oxides or inner scale due to hardness, causing a delay in heating time. As a result, the production time itself sometimes became longer.

Furthermore, in cases where steam condensed water is collected on the boiler side, if any cold water remains, there is a risk that it will be brought into the boiler side and cause scale problems in the boiler. Therefore, when switching from cold water to steam, it is necessary to thoroughly discharge some of the initial condensed water. Alternatively, there are many cases where recovery itself is postponed, leading to heat loss.

In addition, in many chemical industries, there are not only steam heating processes, but also multiple processes before and after the heating process, so it is not enough to simply shorten the heating time. The need to optimize the system was necessary for overall optimization. Previously, workers in each process had to monitor each process individually, and it was necessary to grasp the information as a whole and reflect it in the entire process.

Patent Document 1 describes a method in which vapor is introduced into a heat exchanger and brought into contact with a cooling body in the heat exchanger to liquefy and condense, in which a droplet -like condensation accelerator such as a film-forming amine is introduced into the heat exchanger. It is described that by adding it to the introduced steam, it promotes droplet condensation and increases the condensation efficiency.

JP2019-158255A

Air is discharged from the heat exchanger by installing an air vent in the heat exchanger and increasing the steam valve opening to increase the steam pressure inside the heat exchanger and promote the discharge of steam condensed water. However, there is a limit because the effective heat transfer area of the heat exchanger is limited.

Dirt or rust on the heat transfer surface reduces the overall heat transfer coefficient. In order to prevent rust, it is possible to change the heat exchanger itself to corrosion-resistant stainless steel or titanium, but this would require updating new equipment, and the metal itself has low thermal conductivity, so it would be difficult to install the heat exchanger itself due to the low thermal conductivity of the metal itself. Not realistic from that point of view.

In order to prevent scale formation on heat transfer surfaces, cold water is treated with water. When steam and cold water are used alternately, depending on the timing of switching, hard components and silica in the cold water remaining in the heat exchanger may dry up and form scales at the time of switching. This lowers the overall heat transfer coefficient and further increases the heating time.

Flushing may take some time to drain the cold water remaining in the heat exchanger. This not only increases the amount of waste water, but also increases the time required for the heating and cooling manufacturing process.

In order to improve productivity in production processes involving heat exchangers, it is important to increase the overall heat transfer coefficient of the heat exchanger as much as possible.

In addition, for overall optimization, it is necessary to grasp the progress of the entire process, including not only the parts where steam is used, but also the processes before and after.

The present invention increases the overall heat transfer coefficient of the heat exchanger, and also enables the progress of the entire process, including not only the steam usage area, but also the processes before and after the process, to be grasped. The objective is to provide a method for improving process productivity.

The present invention solves the above problems by the following.

[1] A method for improving the productivity of a production process including a heat exchange process having a heat exchanger using steam as a heat source fluid,
In a method for improving the productivity of a production process by adding a droplet condensation accelerator to the feed water of a boiler that generates the steam or to the steam,
A method for improving the productivity of a production process having a heat exchange step, which comprises adjusting the entire production process by measuring the degree of shortening of the heating time of the heat exchanger by adding a droplet condensation accelerator. .

[2] The production having a heat exchange step according to [1], wherein the degree of shortening of the heating time of the heat exchanger is the degree of shortening of the heating time of the heat exchanger during cold startup. How to improve process productivity.

[3] The heat exchange process according to [1] or [2], which is characterized by adjusting the operation status (work man-hours, work personnel, or input energy) of each process based on the measured temperature increase time reduction degree. A method for improving the productivity of a production process.

[4] The method for improving the productivity of a production process having a heat exchange step according to [1] or [2], wherein the droplet condensation promoter is a volatile droplet condensation promoter.

[5] The method for improving the productivity of a production process having a heat exchange step according to [1] or [2], wherein the droplet-like condensation accelerator has anticorrosive properties.

[6] The method for improving the productivity of a production process having a heat exchange step according to [1] or [2], characterized in that a pH adjuster or an oxygen scavenger is added to the boiler feed water or steam.

[7] A method of performing a heat exchange step using steam and a cooling step using cold water in the heat exchanger, wherein in the cooling step, the cold water remaining in the heat exchanger is removed by the water repellency of the droplet condensation accelerator. The method for improving the productivity of a production process having a heat exchange step according to [1] or [2], characterized in that scale formation due to adhesion of dissolved solids is suppressed by promoting discharge.

[8] When recovering the condensed water from the heat exchanger to the boiler, it is recommended to add a scale inhibitor to the boiler feed water in order to prevent scale components contained in the condensed water from forming scales in the boiler. A method for improving the productivity of a production process having a heat exchange step according to [1] or [2].

[9] The method for improving productivity of a production process having a heat exchange step according to [8], wherein the scale inhibitor is any one or more of polyacrylate, polymaleate, and phosphate.

[10] The droplet condensation promoter of [1] or [2], wherein the droplet-like condensation accelerator is any one or more of oleylamine, octadecylamine, oleylpropanediamine, azelaic acid and its salts, sarcosine derivatives, and polysorbates. A method for improving the productivity of a production process that includes a heat exchange process.

[11] The steam supply line to the heat exchanger is equipped with a desuperheater that sprays water into the superheated steam. The method for improving productivity of a production process having a heat exchange step according to [1] or [2], characterized in that scale formation is suppressed.

According to the present invention, in a production process including a heat exchange step that uses steam as a heat source fluid, by providing a droplet condensation accelerator on the heated steam side, it not only shortens the cold startup time of the target equipment, but also By preventing the adhesion of metal oxides and scale components in cold water, the heating efficiency of the steam can be improved and maintained.

Furthermore, productivity can be maximized by optimizing the entire process of multiple processes.

It is an explanatory view of the addition point of the droplet condensation accelerator in the method of the present invention. It is an explanatory view of the addition point of the droplet condensation accelerator in the method of the present invention. It is an explanatory view of the addition point of the droplet condensation accelerator in a comparative example. It is a graph showing the temperature increase status of the reaction vessel. It is a block diagram showing an example of a production process.

A method for improving productivity according to one aspect of the present invention is a method for improving the productivity of a production process including a heat exchange step having a heat exchanger using steam as a heat source fluid, the method comprising supplying water to a boiler that generates the steam. Alternatively, in a method of improving the productivity of the production process by adding a droplet condensation accelerator to the steam, the degree of reduction in heating time of the heat exchanger due to the addition of the droplet condensation accelerator is measured, and the overall It is characterized by adjusting the production process.

The material of the heat exchanger to which the present invention is applied is not particularly limited, and may be any material that can realize droplet condensation by forming a water-repellent film with the droplet condensation accelerator used, such as mild steel, low Examples include alloy steel, alloy steel, copper, copper alloy, titanium, titanium alloy, aluminum, aluminum alloy, and the like.

In the present invention, the droplet condensation promoter is added to the steam that is introduced into the heat exchanger or to the feed water of the boiler that generates this steam. 1 and 2 show preferred examples of locations where the droplet-like condensation accelerator is added to the steam.

In FIG. 1, steam from a boiler 1 is introduced into a steam header 3 through a pipe 2. Steam in the steam header 3 is supplied to a heat exchanger 5 through piping 4 and to a heat exchanger 7 through piping 6. Furthermore, the steam in the steam header 3 is supplied to the steam header 10 through the piping 8. Steam in the steam header 10 is supplied to a heat exchanger 12 through piping 11 and to a heat exchanger 14 through piping 13.

A pipe 15 branches from the pipe 8. The pipe 15 is further connected to another steam header or steam using equipment (not shown). Piping 15 may also be used as a blow line.

In FIG. 1, pipes 4, 6, 11, and 13 are provided with droplet-like condensation accelerator addition parts 4a, 6a, 11a, and 13a.

In FIG. 2, droplet-like condensation accelerator addition parts 4a, 6a, and 8a are provided in the pipes 4 and 6 and the pipe 8 (but downstream of the branch part of the pipe 15).

FIG. 3 shows a comparative example, in which droplet-like condensation accelerator addition parts 2a and 8a are provided in the pipe 2 and the pipe 8 (but downstream of the branch part of the pipe 15). In FIG. 3, the steam that branches and flows into the pipe 15 also contains the droplet condensation accelerator. Therefore, as shown in FIGS. 1 and 2, it is preferable to add the droplet condensation accelerator only to the steam supplied to the heat exchanger.

In one aspect of the present invention, the reduction in the heating time of the heat exchanger is the reduction in the heating time during cold startup of the heat exchanger.

As an example of an evaluation method for improving heating time, an example of application to a reaction vessel is shown below.

A reaction vessel is a device that indirectly applies heat to the product inside the vessel using steam, and many have a structure called a jacket type. In a reaction vessel, steam is usually continued to flow into the jacket until the set temperature is reached.

By adding a droplet condensation accelerator to this steam or the feed water of the boiler that generates the steam, a high overall heat transfer coefficient can be obtained, resulting in a shorter time to reach the set temperature, as shown in Figure 4. Ru. In many cases, a system is installed in the reaction vessel to record the temperature increase process, so it is possible to monitor the reduction in heating time when producing the same product in the same quantity. Based on the degree of shortening of the heating time, it is possible to optimize the steps before and after the process and improve productivity.

In addition, as another example, a desuperheater may be used that sprays water into superheated steam and absorbs the heat in the steam as the water evaporates, generating steam close to the saturated steam temperature. The water repellency of the droplet-like condensation accelerator can suppress scale formation due to adhesion of dissolved solids derived from spray water that accumulate in the heat exchanger.

If there are multiple processes before and after the steam heating process, overall optimization can be achieved by calculating the working time, intermediate raw material inventory, input energy, and heating shortening time for each process and performing feedback control. For example, it is possible to adjust the operating status of each process (eg, number of work hours, number of workers, input energy, etc.).

FIG. 5 is a flow diagram of a production process with manufacturing steps A1, A2, and A3 proceeding in parallel. Note that the product is manufactured through manufacturing steps A1, A2, and A3. The manufacturing process A3 includes a heating heat exchanger and a cooling heat exchanger. The heating heat exchanger is supplied with steam and the condensed water is recovered or discharged. Cold water from the chiller is circulated through the cooling heat exchanger. A droplet condensation accelerator is added to the steam described above or to the feed water to the boiler for generating this steam.

For example, in FIG. 5, even if the productivity of manufacturing process A3 is improved beyond the capacity of manufacturing process A1's production volume per unit time or manufacturing process A2's capacity of manufacturing volume per unit time, the manufacturing process will proceed in parallel. If the productivity of manufacturing steps A1 and A2 remains unchanged, the productivity of the entire process cannot be improved. Therefore, while monitoring the inventory amount of intermediate products in manufacturing processes A1 and A2 and the degree of productivity improvement in manufacturing process A3, we reviewed the allocation of workers to processes A1, A2, and A3, and changed the manufacturing equipment for processes A1 and A2. By performing feedback control such as increasing the amount of energy input, it is possible to improve the productivity of the entire process.

In the present invention, the droplet-like condensation accelerator may be one that imparts water repellency to the metal surface to which it is applied, and is preferably one that is volatile in a steam system. Examples of the droplet condensation promoter include, but are not limited to, any one or more of oleylamine, octadecylamine, oleylpropanediamine, azelaic acid and its salts, sarcosine derivatives, and polysorbate.

These droplet-like condensation accelerators may be used alone or in combination of two or more.

The amount of the droplet condensation accelerator to be added is sufficient as long as the effect of promoting droplet condensation in the heat exchanger can be obtained, and although it varies depending on the type of the droplet condensation accelerator and the type of the heat exchanger, usually, It is preferably about 0.001 to 10 mg/L, particularly about 0.01 to 2.0 mg/L, based on the amount of steam calculated as water.

The droplet-like condensation accelerator may be added intermittently or continuously, but from the viewpoint of stably maintaining a water-repellent film due to condensation on the surface of the cooling body in the heat exchanger, continuous addition is preferable.

The droplet condensation accelerator may be dissolved in a solvent such as methanol, ethanol, isopropanol, etc. in addition to water and added to the steam or feed water, but it is also possible to make an aqueous emulsion using an emulsifier and add this to the steam or feed water. You can.

In one aspect of the invention, a volatile droplet condensation promoter may be used and added to boiler feed water, pre-heat exchanger steam, or both.

In one aspect of the present invention, prevention of metal oxide deposition due to corrosion of the heat exchanger is also performed in parallel. A suitable method for preventing corrosion of a heat exchanger is to use one or more of a droplet condensation accelerator, a pH adjuster, and an oxygen scavenger that have anticorrosive properties in a boiler system that generates heated steam.

In one aspect of the present invention, in a heat exchanger that performs heat exchange with steam and cooling with cold water in separate steps, the water repellency of the droplet condensation accelerator promotes discharge of cold water remaining in the heat exchanger. Thereby, scale formation due to adhesion of dissolved solids can be suppressed. In addition, as a scale component, any one or more of the hardness in cold water, silica, iron, copper, and zinc is illustrated.

In one aspect of the present invention, when condensed water from a heat exchanger is recovered and used as boiler water, boiler feed water is A scale inhibitor is preferably added in an amount equal to or more than the amount required to prevent scale components. Examples of the scale inhibitor include any one or more of polyacrylates, polymaleates, and phosphates.

In one aspect of the present invention, if a desuperheater is installed, which sprays water into the superheated steam and absorbs the heat in the steam as the water evaporates, generating steam close to the saturated steam temperature, The water repellency of the condensation accelerator suppresses scale formation due to adhesion of dissolved solids derived from spray water that accumulates inside the heat exchanger, thereby reducing the frequency of cleaning the attemperator.

1 Boiler 3,10 Steam header 5,7,12,14 Heat exchanger

Claims (11)

A method for improving the productivity of a production process including a heat exchange step having a heat exchanger using steam as a heat source fluid, the method comprising:
The production process includes a plurality of manufacturing steps that proceed in parallel, and some of the manufacturing steps (A3) are equipped with a heating heat exchanger using steam from a boiler as a heat source,
A method for improving the productivity of a production process by adding a droplet condensation accelerator to the feed water of the boiler or the steam from the boiler,
The degree of shortening of the heating time of the heating heat exchanger in the manufacturing process (A3) by adding the droplet condensation accelerator is measured, and the heating time of the heating heat exchanger in the manufacturing process (A3) is measured. Production of a production process having a heat exchange process characterized by allocating workers to each manufacturing process based on the degree of shortening and controlling the amount of energy input to manufacturing equipment for manufacturing processes other than the manufacturing process (A3). How to improve your sex. The production process having a heat exchange step according to claim 1, wherein the degree of reduction in the temperature increase time of the heat exchanger is the degree of decrease in the temperature increase time during cold startup of the heat exchanger. How to improve your sex. 3. The method for improving productivity of a production process having a heat exchange step according to claim 1 or 2, wherein the droplet-like condensation promoter is a volatile droplet-like condensation promoter. 3. The method for improving productivity of a production process having a heat exchange step according to claim 1 or 2, wherein the droplet-like condensation accelerator has anti-corrosion performance. 3. The method for improving productivity of a production process having a heat exchange step according to claim 1 or 2, characterized in that a pH adjuster or an oxygen scavenger is added to the boiler feed water or steam. In the heat exchanger, a heat exchange step using steam and a cooling step using cold water are performed, and in the cooling step, the water repellency of the droplet condensation accelerator promotes discharge of cold water remaining in the heat exchanger. 3. The method for improving productivity in a production process having a heat exchange step according to claim 1, wherein scale formation due to fixation of dissolved solids is suppressed by this. When the condensed water from the heat exchanger is recovered to the boiler, a scale inhibitor is added to the boiler feed water in order to prevent scale components contained in the condensed water from forming scales in the boiler. A method for improving productivity of a production process comprising the heat exchange step according to claim 1 or 2. 8. The method for improving productivity of a production process having a heat exchange step according to claim 7 , wherein the scale inhibitor is any one or more of polyacrylate, polymaleate, and phosphate. 3. The heat exchange step according to claim 1 or 2, wherein the droplet-like condensation accelerator is one or more of oleylamine, octadecylamine, oleylpropanediamine, azelaic acid and its salts, sarcosine derivatives, and polysorbates. How to improve productivity in production processes. The steam supply line to the heat exchanger is equipped with a desuperheater that sprays water into the superheated steam, and the water repellency of the droplet condensation accelerator prevents scale formation due to the adhesion of dissolved solids derived from the sprayed water. 3. The method for improving productivity of a production process having a heat exchange step according to claim 1 or 2, wherein the heat exchange step is suppressed. 3. The method for improving productivity of a production process having a heat exchange step according to claim 1 or 2, wherein the manufacturing step (A3) includes a cooling heat exchanger through which cold water is passed.

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