JP6981614B2 - Drying / concentration system - Google Patents

Description

The present invention includes a heat transfer member arranged in a drying / concentrating chamber through which steam for drying / concentrating passes, and the heat transfer member is brought into contact with the heat transfer member in the drying / concentrating chamber. The present invention relates to a drying / concentrating system provided with a drying / concentrating machine that transfers the heat of the steam for drying / concentrating passing through the inside of the object to the object to be processed to dry / concentrate the object to be processed.

For example, in a drying system equipped with a dryer for drying an object to be treated such as sludge, heat is recovered from steam (dried exhaust gas) evaporated from the object to be processed by a heat exchanger, while drying is performed by a multi-tube heat transfer tube of the dryer. The steam supplied as a heat source for drying (drying steam) is condensed and the discharged drain is re-evaporated into low-pressure steam, and the low-pressure steam is sucked and compressed by the first-stage compressor, and then compressed. A steam recompression (VRC) technology is known in which a so-called heat pump cycle is formed, in which high-temperature high-pressure steam is obtained as drying steam of a dryer by compressing to a high pressure with a subsequent second-stage compressor (for example, patent). Refer to Document 1 etc.). Here, the high-temperature high-pressure steam is the saturated steam S3 in Patent Document 1.

However, the technology for controlling the amount of heat of the high-temperature and high-pressure steam obtained in the drying system using this VRC technology is not yet sufficient, and the obtained high-temperature and high-pressure steam exceeds the amount of heat required for drying. Part of the high-temperature and high-pressure steam is released to the outside such as outdoors as surplus steam. The release of excess steam to the outside is not preferable in terms of appearance because it is contrary to energy saving and also generates unnecessary white smoke to the outdoors and the like.
On the other hand, in the field of heat recovery, various techniques have been developed as a technique for adjusting the amount of heat recovery in a heat exchanger (see, for example, Patent Documents 2 to 4), but there is still room for improvement. It is something to leave.

JP-A-2015-81712 Special Publication No. 47-18482 Japanese Unexamined Patent Publication No. 2002-257497 Japanese Unexamined Patent Publication No. 52-79101

The calorific value of the steam recovered in the drying system may vary depending on factors such as the type and condition of the object to be treated and the input amount, and it is not possible to adjust the heat recovery amount in the heat exchanger or control it in the compressor. , High temperature and high pressure steam may exceed the required amount of heat. In most cases, the increased amount of steam evaporating from the heat exchanger causes the compression by the compressor to exceed the amount of heat required by the drying system, resulting in higher steam pressure than necessary. It will cause a rise.

As a countermeasure, in Patent Document 1, the reevaporation temperature of the drain in the heat exchanger 45 is determined by the suction pressure (primary side pressure of the compressor) of the first-stage compressor, but the suction pressure is changed. It is conceivable to do. However, even if this change is made, the re-evaporation temperature changes only slightly, and it takes time for the change in the amount of re-evaporation of the drain to occur, resulting in poor reaction responsiveness. Therefore, the heat exchanger 45 The fact is that it is insufficient to control the amount of heat recovery in. In addition, by changing the primary pressure of the first-stage compressor, the effect may greatly fluctuate the balance of the pressure of the gas phase system of the drying system, and it may become difficult to converge the fluctuation. be.

As another countermeasure, there is a method of providing a throttle valve in the piping path of the saturated steam S3 in Patent Document 1, which is a high-temperature and high-pressure steam, so that an excessive amount of heat is not supplied to the multi-tube heating tube 11 of the dryer 1. .. However, the effect of squeezing this valve takes time until the amount of re-evaporation of the drain due to heat exchange in the heat exchanger 45 changes, and until then, the excess steam is continuously discharged to the outside for a long time. Alternatively, if a new fluctuation of the object to be processed occurs before the effect of throttled the valve becomes steady, it becomes very difficult to adjust the opening degree of the valve. For example, the amount of re-evaporated steam decreases too much, and a large amount of auxiliary steam (saturated steam S0) must be supplied in order to supplement the amount of steam required for drying the object to be processed, resulting in an energy-saving operation as a drying system. There can be situations where it is not. It can be said that the method of directly adjusting the high-temperature and high-pressure steam using a valve in this way is inferior in reaction responsiveness and is not preferable in terms of energy saving.

In the above description, the case where a dry product having a small amount of evaporation component is obtained from a solid object to be treated containing a large amount of evaporation component such as water has been described. However, the evaporation component such as water is evaporated from the liquid object to be treated. The same applies to the case of obtaining a concentrated liquid substance. Hereinafter, drying or concentration is referred to as drying / concentration.

In view of the above circumstances, it is an object of the present invention to provide a drying / concentrating system capable of controlling the calorific value of high-temperature and high-pressure steam with good reaction response.

The drying / concentrating system of the present invention that solves the above object is provided with a heat transfer member that is arranged in the drying / concentrating chamber and through which the drying / concentrating steam passes, and heat transfers the object to be treated in the drying / concentrating chamber. Drying / concentrator provided with a drying / concentrating machine that transfers the heat of the drying / concentrating steam that passes through the inside of the heat transfer member to the object to be processed and dries / concentrates the object to be processed. In the enrichment system
The steam recovered from the drying / concentrating chamber and the drain recovered from the heat transfer member are supplied, the steam is used as heat exchange steam, and the drain is evaporated using the heat amount of the heat exchange steam to steam. With a heat exchanger that discharges
A compressor that compresses the steam discharged from the heat exchanger to obtain high-temperature and high-pressure steam that is reused as the drying / concentrating steam.
Depending on the state of the steam discharged from the heat exchanger, characterized in that a first adjusting unit capable of adjusting the supply amount of the drain supplied to the heat exchanger.

As described above, drying or concentrating is referred to as drying / concentrating, and the drying / concentrating system of the present invention selects a dried product having a small amount of evaporation components from a solid object to be treated containing a large amount of evaporation components such as moisture. It can be obtained, or an evaporative component such as water can be evaporated from a liquid object to be treated to obtain a concentrated liquid (concentrate).

According to the drying / concentrating system of the present invention, the amount of heat recovered in the heat exchanger can be adjusted by adjusting the amount of drain supplied to the heat exchanger, and as a result, as steam for drying / concentrating. The amount of heat of the obtained high-temperature and high-pressure steam can be controlled.

Here, as the drying / concentrating machine, a heating device is provided in the drying / concentrating chamber, and a continuous type configured to bring an object to be treated into contact with the heat transfer surface of the heating device to evaporate evaporative components such as water. A conduction heat transfer type drying / concentrator may be used, and more specifically, a continuous conduction heat transfer type drying / concentrator in which the heating device is a multi-tube heating tube may be used, a paddle dryer or the like may be used. May be.

Further, the first adjusting unit may be a manual type (for example, a manual valve) that adjusts the supply amount by receiving an operation according to the state of the steam discharged from the heat exchanger. ..

Further, the heat exchanger may be a vertical type (vertical installation) or a horizontal type (horizontal installation).

Further, the heat exchanger may be a dry heat exchanger or may have an aspect of a full liquid heat exchanger.

Further, in the drying / concentrating system of the present invention, the first adjusting unit may be capable of adjusting the supply amount according to the degree of superheat of the steam discharged from the heat exchanger.

Here, the first adjusting unit is a manual type (for example, a manual valve) that adjusts the supply amount by receiving an operation according to the degree of superheat of the steam discharged from the heat exchanger. May be good.

Further, the first adjusting unit may be an automatic expansion valve that mechanically (self-poweredly) adjusts the supply amount.

Further, the first adjusting unit may include a calculation unit for calculating the degree of superheat of steam discharged from the heat exchanger, and the first adjusting unit may supply the supply according to the calculation result of the calculation unit. It may be a control unit that automatically adjusts the amount.

Further, in the drying / concentrating system of the present invention, an output unit for outputting information according to the state of the high-temperature high-pressure steam obtained by the compressor is provided.
The first adjusting unit may be capable of adjusting the supply amount based on the degree of superheat of the steam discharged from the heat exchanger and the information from the output unit.

Here, the first adjusting unit may be a manual type (for example, a manual valve) that adjusts the supply amount.

Further, the first adjusting unit includes a calculation unit for calculating the degree of superheat of the steam discharged from the heat exchanger, and the output unit has a detection value of the pressure of the high-temperature high-pressure steam and a preset pressure set value. The first adjusting unit outputs information according to the deviation from the above, and the first adjusting unit uses the calculation result (heat superheat degree of steam) of the calculation unit and the output result (information according to the deviation) of the output unit. Based on this, it may be a control unit that automatically adjusts the supply amount.

Further, in the drying / concentrating system of the present invention, the heat exchanger exchanges heat between the gas in which the non-condensable gas is mixed with the heat exchange steam and the supplied drain, and evaporates the drain. It is a thing
An output unit that outputs information according to the state of the high-temperature and high-pressure steam obtained by the compressor, and
The mode may include a second adjusting unit that can adjust the mixing amount of the non-condensable gas with the heat exchange steam based on the information from the output unit.

According to this aspect, by adjusting the mixing amount of the non-condensable gas with the heat exchange steam, the heat recovery amount in the heat exchanger and the supply amount of the drain supplied to the heat exchanger can be adjusted. It can be adjusted separately, and as a result, the amount of heat of the high-temperature and high-pressure steam reused as the drying / condensing steam can be controlled in two steps.

Here, the second adjusting unit may be a control unit that performs an calculation according to the information from the output unit and automatically adjusts the mixing amount according to the result of the calculation. Further, it may be a manual type (for example, a manual valve) that adjusts the mixing amount by receiving an operation according to the display of the result of this calculation. Alternatively, it may be a manual type (for example, a manual valve) that adjusts the mixing amount by receiving an operation according to a meter display or the like of the output result of the output unit.

Further, the heat exchanger does not always exchange heat between the gas in which the non-condensable gas is mixed with the heat exchange steam and the supplied drain, and the heat exchange vapor has the non-condensable property. In some cases, heat exchange may occur between the gas that is not mixed with the gas and the drain that is supplied.

Further, in the drying / concentrating system of the present invention, the drying / concentrating chamber may be provided with a supply port for the non-condensable gas.

Further, in this embodiment, the non-condensable gas is already mixed with the steam recovered from the drying / concentrating chamber.

Further, in the drying / concentrating system of the present invention, the non-condensable gas supply port may be provided in the path for sending the steam recovered from the drying / concentrating chamber to the heat exchanger.

According to this aspect, the non-condensable gas may or may not be already mixed with the steam recovered from the drying / concentrating chamber, and the non-condensable gas may be mixed with the steam recovered from the drying / concentrating chamber. Gas can be added later.

Further, in the drying / concentrating system of the present invention, the heat exchanger may be provided with the non-condensable gas supply port.

Also in this embodiment, the non-condensable gas may or may not be already mixed with the steam recovered from the drying / concentrating chamber, and the non-condensable gas may be mixed with the steam recovered from the drying / concentrating chamber. Can be added later.

According to the drying / concentrating system of the present invention, the calorific value of high-temperature and high-pressure steam can be controlled with good reaction response.

It is a system diagram of the drying system of 1st Embodiment of this invention. FIG. 3 is a block diagram schematically showing the drying system shown in FIG. 1 centering on a heat exchanger. It is a system diagram of the drying system of 2nd Embodiment.

Hereinafter, the drying system according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a system diagram of a drying system according to the first embodiment of the present invention.

In the drying system D1 of the first embodiment, the dryer 1, the dust collector 2, the drain tank 3, the heat exchanger 4, the steam blower 5 which is the first stage compressor, and the second stage compression are performed. It includes a steam compressor 6, a system header 7, an overheater 8, and the like.

The dryer 1 shown in FIG. 1 is a conduction heat transfer type dryer, and more specifically, a continuous conduction heat transfer dryer capable of continuously processing an object to be processed. The dryer 1 has a drying chamber 11 and a multi-tube heating tube 12 arranged in the drying chamber 11. The drying chamber 11 is a hollow one having a substantially circular or substantially elliptical cross section, and is supported in a horizontally extending state by a machine frame or the like (not shown). Hereinafter, the direction in which the drying chamber 11 extends may be referred to as an extension direction. The drying chamber 11 is provided with an input port 111, an discharge port 112, a carrier steam port 113, and an exhaust port 114. The charging port 111 is a port for charging sludge and other objects to be treated, and is located on the left side side of the drying chamber 11 shown in FIG. 1, for example, at the upper end portion of the drying chamber 11. The discharge port 112 is an opening in which the object to be charged from the input port 111 is dried by being subjected to a drying process while staying in the drying chamber 11, and is discharged as a dried product. be. The discharge port 112 is located on the right side of the drying chamber 11 shown in FIG. 1 and is provided at a position higher than the bottom of the drying chamber 11. A rotary valve 1121 is provided at the discharge port 112. The object to be charged from the charging port 111 moves from the left side to the right side in the drying chamber 11 shown in FIG. 1, and is eventually discharged from the discharging port 112.

The carrier steam port 113 is a port for introducing the carrier steam, which is the superheated steam obtained by the superheater 8, into the drying chamber 11. A temperature sensor 85 for measuring the temperature of the carrier steam (superheated steam) is provided between the superheater 8 and the carrier steam port 113, and the signal from the temperature sensor 85 and the carrier steam temperature of the carrier steam temperature control unit 81 are provided. The overheater 8 is controlled based on the set value. The carrier steam is provided with steam from the system header 7. In FIG. 1, the path of the carrier steam is shown from the steam path for drying to the superheater 8.

The exhaust port 114 is a port for discharging the steam evaporated from the object to be processed in the drying chamber 11 to the outside of the drying chamber 11 together with the carrier steam introduced from the carrier steam port 113. Hereinafter, the carrier vapor and the vapor evaporated from the object to be processed are collectively referred to as recovered vapor.

A dust collector 2 is connected to the exhaust port 114. The dust collector 2 is provided with a bag filter 21, and the steam recovered from the drying chamber 11 is sent to the heat exchanger 4 after the bag filter 21 removes fine powder and the like.

The dust collector 2 is provided with a spraying mechanism 22 for cleaning the bug filter 21, and is in the direction opposite to the direction in which the recovered steam flows into the bug filter 21 (primary side of the bug filter 21) (bug filter). From the secondary side of 21), the attached fine powder is blown off into the drying chamber 11 at a predetermined timing. The superheated steam supplied to the spraying mechanism 22 is obtained by heating the steam supplied from the system header 7 by a superheater (not shown) while controlling the temperature with a temperature control device (not shown). be.

The multi-tube heating tube 12 is rotatably arranged in the drying chamber 11 around a rotating shaft along the extending direction, and a hollow shaft member 121 is provided in the rotating shaft portion. In the multi-tube heating tube 12, the shaft member 121 is rotated around a rotating shaft by being rotated by a motor or the like (not shown). Further, the multi-tube heating tube 12 is composed of a plurality of heating tubes 122a arranged along the shaft member 121 around the shaft member 121. For example, these plurality of heating tubes 122a are arranged concentrically around the axis of rotation, and a large number of heating tubes 122a arranged between the concentric circles or on the concentric circles are arranged at predetermined intervals from each other. Has been done. A hemispherical header 123 composed of a can plate and a mirror plate communicating with the heating tube 122a is provided at both ends of the plurality of heating tubes 122a in the extending direction. Although not shown, a plurality of angle steel materials are bridged between the headers 123 at both ends thereof at predetermined intervals in the rotation direction of the header 123. A plurality of lifters and feed vanes (not shown) are provided on these angle steel materials at predetermined intervals in the extending direction. The lifter scrapes up the object to be treated that stays in the drying chamber 11 when the multi-tube heating tube 12 rotates. When the multi-tube heating tube 12 rotates, the feed vane sends the object to be treated staying in the drying chamber 11 to the discharge port 112 side.

Further, drying steam is supplied to the inlet side of the shaft member 121 via a rotary joint and flows into the header 123, and further flows from the header 123 into each heating tube 122a to heat each heating tube 122a. ..

In addition, a part of the drying steam here is also used as heat-retaining steam for the drying chamber 11 and the dust collector 2 in steam trace pipes or heat-retaining jackets (hereinafter referred to as steam trace pipes, etc.) provided on the outer surfaces of the respective outer surfaces. Will be supplied.

In the present embodiment, since the saturated steam is sent into each heating tube 122a as drying steam, each heating tube 122a is kept heated to a substantially constant temperature in the extending direction. Is done. In the present embodiment, the saturated steam passing through the multi-tube heating tube 12 corresponds to an example of drying steam, and the multi-tube heating tube 12 corresponds to an example of a heat transfer member. The drain generated by condensing the drying steam supplied to each heating pipe 122a flows into the header 123 on the discharge port side, further flows into a siphon pipe (not shown) provided in the header 123, and then the discharge port. It passes through the hollow shaft member 121 on the side and the rotary joint connected to the shaft member 121, and is collected in the drain tank 3 described in detail later. The drain generated in the steam trace pipe or the like is also collected in the drain tank 3. A steam trap 31a having a built-in needle valve is provided between the drying chamber and the drain tank 3 and functions as an expansion valve and a steam trap. Similarly, a steam trap 31b having a built-in needle valve is provided between the steam trace pipe and the like and the drain tank 3. For example, if the drain is on the primary side (upstream side) of the steam traps 31a and 31b, the temperature is 160 ° C. of 0.5 MPaG, and a part of the drain that has passed through the steam traps 31a and 31b is re-evaporated (hereinafter, hereinafter). (Sometimes referred to as re-evaporation steam), for example, the temperature drops to about 90 ° C. of about −0.04 MPaG.

The drain collected in the drain tank 3 is sent to the heat exchanger 4 by the drain pump 32 via the three-way valve 33 in the path of the arrow Sl. A drain control valve 35 is provided between the three-way valve 33 and the heat exchanger 4, and when the drain control valve 35 is completely closed (hereinafter, may be referred to as fully closed), heat exchange is performed. No drain is sent to the vessel 4, and the drain circulates along the path of arrow C. The drain control valve 35 also has a function as an expansion valve, and the temperature of the drain passing through the drain control valve 35 is further lowered from the state in the drain tank 3.

Further, of the drain collected in the drain tank 3, the re-evaporated steam is sent from the upper part of the drain tank 3 to the heat exchanger 4 by the path of the arrow Sa. That is, the heat exchanger 4 is supplied with the recovered steam that has passed through the dust collector 2, and is also supplied with drain and re-evaporation steam.

A liquid level meter (not shown) is provided in the drain tank 3, and when the drain tank 3 exceeds a certain liquid level, the drain is drained from the drain tank 3 so that the liquid level does not exceed a certain level. Be controlled.

Further, as described above, the drain is sent to the heat exchanger 4 by the drain pump 32, but when the steam blower 5 is activated, the region in the heat exchanger 4 to which the drain is supplied becomes a negative pressure, while the pressure becomes negative. Since the steam in the heating pipe 122a, the steam trace pipe, etc. has a positive pressure, the drain in the drain tank 3 can be sent even if the drain pump 32 is not provided, depending on the arrangement relationship between the drain tank 3 and the heat exchanger 4. .. In addition, the steam traps 31a, 31 or the path of the arrow Sa described above can be eliminated.

FIG. 2 is a block diagram schematically showing the drying system shown in FIG. 1 centering on a heat exchanger.

The dryer 1 is shown at the left end of FIG. 2, and the steam traps 31a and 31b in which the needle valve shown in FIG. 1 is built are marked with a valve symbol as 31.

The heat exchanger 4 shown in FIG. 2 is, for example, a vertical (vertical) heat exchanger, and a tube 45, which is a large number of cylindrical straight tubes extending in the vertical direction, is provided in the heat exchanger 4. Has been done. The upper and lower ends of the tube 45 are connected to the can plate 43, and in the heat exchanger 4, the recovered steam is separated from the drain and the re-evaporation steam by the can plate 43 and the tube 45. The recovered steam passes through the tube 45 from top to bottom.

The drain is sprayed in the form of mist toward the upper end portion of the tube 45, and heat exchange is performed by contacting the outer peripheral surface of the tube 45, and the drain is re-evaporated to generate steam. The generated steam is sucked by the steam blower 5. On the other hand, due to heat exchange, most of the recovered steam becomes condensed water, and the rest of the recovered steam flows out of the heat exchanger 4 as steam.

The drain that is sprayed onto the tube 45 and flows down without evaporating to reach the lower can plate 43 of the heat exchanger 4 is discharged from the discharge port provided above the lower can plate 43 by the path C2 shown in FIG. It is returned to the drain tank 3. Since this discharge port is provided immediately above the lower can plate 43, almost no drainage is generated in the heat exchanger. In the field of heat exchangers, a heat exchanger in such a manner that a liquid (drain in the present invention) is not stored in the heat exchanger is sometimes referred to as a dry heat exchanger.

When the drain is sprayed on the tube 45, the path of spraying from two places is shown in FIG. 2, but it is preferable to spray the drain from two or more places in multiple directions. Further, it may be sprayed from the vertical direction along the extending direction of the tube 45. Further, in order to make the tube 45 more mist and spray it on the tube 45, a mist nozzle may be provided at the end of the path S1 (see FIG. 1) which is a connection portion with the heat exchanger 4.

On the other hand, as shown in FIG. 1, the condensed water generated from the recovered steam is drained to a water treatment facility or the like by the second drain pump 911 along the path of the arrow W1. Further, the recovered steam flowing out of the heat exchanger 4 flows into the second heat exchanger 921. The second heat exchanger 921 is supplied with cooling water or the like from a cleaning tower (not shown), whereby the water content in the recovered steam is further condensed. The condensed water is also drained to a water treatment facility or the like by the second drain pump 911 along the route of arrow W2. The recovered steam flowing out of the second heat exchanger 921 is sucked by the exhaust fan 922, and if the recovered steam contains an odor component, it is exhausted to a deodorizing facility (not shown) or the like.

A temperature sensor 461 and a pressure sensor 462 are provided between the heat exchanger 4 and the steam blower 5. The temperature sensor 461 measures the temperature of the steam sucked by the steam blower 5, and outputs information about the temperature. The pressure sensor 462 measures the pressure of the steam sucked by the steam blower 5, and outputs information about the pressure. As shown in FIG. 2, the drying system D1 of the present embodiment is provided with a control unit PLC. In the control unit PLC, the information of the temperature sensor 461 and the pressure sensor 462 is input, and the degree of superheat of the steam flowing into the steam blower 5 from the heat exchanger 4 is calculated. The set value SN1 of the degree of superheat is stored in advance in the control unit PLC, the calculated value of the degree of superheat and the set value SN1 are compared, and the opening degree of the drain control valve 35 is controlled according to the comparison result. The control signal is output to the drain control valve 35. For example, a PID control signal or the like is output to the drain control valve 35 based on the deviation between the calculated value of the degree of superheat and the set value SN1, and the opening degree of the drain control valve 35 is controlled. Briefly, if the calculated value is higher than the set value SN1, a control signal for narrowing the opening degree of the drain control valve 35 is output, the amount of drain supplied to the heat exchanger 4 decreases, and heat exchange occurs. The amount of steam generated in the vessel 4 is suppressed. On the contrary, if the calculated value is lower than the set value SN1, a control signal for expanding the opening degree of the drain control valve 35 is output, the amount of drain supplied to the heat exchanger 4 increases, and the heat exchanger 4 increases. The amount of steam generated increases.

In addition, the control unit PLC is displayed with information such as the value of the degree of superheat or the opening degree of the drain control valve 35 required by the comparison result, and the opening degree of the drain control valve 35 is manually operated based on the information. You may. Further, the drain control valve 35 may be a self-powered automatic expansion valve provided with a temperature sensitive portion that simultaneously detects pressure and temperature. The drain control valve 35 and the control unit PLC correspond to an example of the first adjusting unit, and when the opening operation of the drain control valve 35 is manually performed, the drain control valve 35 corresponds to an example of the first adjusting unit. It will be. The above-mentioned automatic expansion valve also corresponds to an example of the first adjusting unit.

In the steam blower 5 that sucks steam from the heat exchanger 4, the suction pressure is controlled to be constant. The steam blower 5 is, for example, a roots compressor. The steam sucked by the steam blower 5 is boosted by the steam compressor 6 on the downstream side to become high-temperature and high-pressure steam. The steam compressor 6 is a screw type compressor. In both the steam blower 5 and the steam compressor 6, water is injected to control the degree of superheat. In this embodiment, the steam blower 5 and the steam compressor 6 are arranged in series to form a two-stage compression system, and the steam blower 5 in the previous stage sucks steam below the atmospheric pressure and from the atmospheric pressure to the atmospheric pressure. It is used to increase the pressure to a positive pressure that slightly exceeds the above, and the steam compressor 6 in the subsequent stage is used to further increase the temperature and pressure.

The high temperature and high pressure steam obtained by the steam compressor 6 is sent to the system header 7. As shown in FIG. 1, a check valve 61 is provided between the steam compressor 6 and the system header 7.

Drying steam is sent from the system header 7 toward the dryer 1. A pipe SP (see FIG. 1) to which auxiliary steam heated by an auxiliary steam boiler (not shown) is sent is connected to the system header 7. Further, the system header 7 is provided with a steam pressure gauge 71 for drying. The drying steam pressure gauge 71 receives an output signal (pressure value) from the pressure sensor 75 that measures the pressure of the drying steam in the system header 7, performs an calculation on the pressure of the drying steam, and performs drying. It displays the pressure of steam for drying and outputs a control signal based on the pressure of steam for drying.

Specifically, it is calculated based on the information from the pressure sensor 75 (the actual pressure value of the system header 7) and the preset pressure set value SN2 that is optimal as the drying steam in the drying steam pressure gauge 71. Is performed, information is output based on the calculation result, control signals are output, and these are displayed. The steam pressure gauge 71 for drying corresponds to an example of the output unit.

Further, as shown in FIG. 1, the pipe SP to which the auxiliary steam is sent is provided with the auxiliary steam control valve 72, and the auxiliary steam control valve 72 is opened by the drying steam pressure gauge 71. Be controlled.

Specifically, when the pressure of the drying steam (high temperature and high pressure steam generated by the steam compressor 6) in the system header 7 is lower than the pressure set value SN2, the actual pressure of the pressure set value SN2 and the system header 7 The opening degree of the auxiliary steam control valve 72 is controlled by using a PID control signal or the like based on the deviation from the value. The steam for drying is mainly covered by auxiliary steam when the drying system D1 is started, and most of the steam is covered by high-temperature high-pressure steam from the steam compressor 6 in steady operation.

Here, regarding the control of drain supply to the heat exchanger 4 in the drying system D1 of the present embodiment, the relationship between the first adjusting unit and the drying steam pressure gauge 71, which is an output unit, will be described.

As described above, the drying steam pressure gauge 71 stores in advance the pressure setting value SN2 of the drying steam in the system header 7, and for example, the actual pressure value which is the information from the pressure sensor 75 is the pressure setting. In the case of a high pressure exceeding the value SN2, the correction value Δt is calculated as an example based on the deviation between the actual pressure value and the pressure set value SN2. This correction value Δt is output from the drying steam pressure gauge 71 to the control unit PLC, and in the control unit PLC, for example, the correction value Δt is added to the set value SN1 based on the correction value Δt and the set value SN1 of the degree of superheat. Then, the new set value SN1 is updated. A series of processes of updating the information of the pressure sensor 75 to the new set value SN1 is repeated at regular time intervals.

The opening degree control of the drain control valve 35 described above is performed by the updated setting value SN1 of the degree of superheat. That is, the drain supply amount is adjusted based on the information according to the deviation obtained by the drying steam pressure gauge 71 and the calculated value of the degree of superheat calculated by the control unit PLC.

By this control, the opening degree of the drain control valve 35 is adjusted while keeping the suction pressure in the steam blower 5 constant, and the heat exchanger 4 generates it while keeping the compression ratio in the steam compressor 6 constant. The amount of steam produced can be changed. Then, the pressure of the high-temperature high-pressure steam (drying steam in the system header 7) generated by the steam compressor 6 also quickly converges to the pressure set value SN2. As a result, the amount of heat of the drying steam supplied to the dryer 1 can be adjusted without significantly changing the balance of the pressure of the gas phase system of the drying system D1.

More specifically, for example, if the operation of narrowing the opening degree of the drain control valve 35 is performed, the amount of steam generated in the heat exchanger 4 decreases, and thereby the pressure of the drying steam in the system header 7 also decreases. However, the drying steam supplied to the dryer 1 is reduced to an appropriate amount of heat. Further, in the past, when the system header 7 became excessive pressure, the regulating valve 73 was opened and the excess steam was released to the atmosphere outdoors, but the system header was used. Since the pressure of 7 quickly converges to the pressure set value SN2, waste such as release to the atmosphere to the outdoors or the like can be reduced.

Further, since it is not necessary to adjust the suction pressure in the steam blower 5 and the compression ratio in the steam compressor 6, the increase in power consumption is eliminated and energy saving operation can be realized.

Furthermore, in the prior art, the drying steam supplied to the multi-tube heating tube 12 was directly adjusted by the throttle valve 901, but this is no longer necessary.

The drying system D1 of the present invention is configured as described above as an example, and an example of an operation method of the present system will be described below.

First, the exhaust fan 922 and the equipment (not shown) downstream of the exhaust fan 922 are started, and the pressure in the drying chamber 11 is maintained at about atmospheric pressure (−0.02 to +0.1 kPaG) by automatic control. Further, the second drain pump 911 and the equipment (not shown) downstream of the second drain pump 911 are started. Cooling water is supplied to the second heat exchanger 921.

Next, the auxiliary steam is controlled and supplied to the drying steam pressure gauge 71 so that the inside of the system header 7 becomes 0.5 MPaG and about 159 ° C., and the steam from the system header 7 is partially multi-tube. A part of the steam for drying is supplied to the heating tube 12 and a part of the steam is supplied to the drying chamber 11 and the dust collector 2 for heat retention. The multi-tube heating tube 12 is rotated by starting a motor (not shown), and steam flows in the rotated state.

At the stage of heating the multi-tube heating tube 12 and keeping the heat of the drying chamber 11 and the dust collector 2, non-condensable gas such as air in the multi-tube heating tube 12 and the steam trace pipe and the like flows into the drain tank 3 together with the drain. Since it flows in, it is discharged from the drain tank 3 from a discharge port (not shown) of the drain tank 3. In addition to the drain tank 3, the operation of discharging the non-condensable gas, which is unnecessary at the time of starting the drying system, to the outside of the drying system D1 is performed at an appropriate timing from an appropriate place (not shown). .. When the drain tank 3 exceeds a certain liquid level, the drain is drained from the drain tank 3.

After the temperature sensor (not shown) in the multi-tube heating tube 12 reaches a predetermined temperature, the non-condensable gas discharge port from the drain tank 3 described above is closed. Then, the drain pump 32 is started, and the drain is supplied to the heat exchanger 4.

Next, the superheater 8 is energized, and under the control of the carrier steam temperature control unit 81, a part of the steam from the system header 7 flows into the drying chamber 11 as carrier steam at about 0.0 MPaG and about 160 ° C. .. The steam from the system header 7 supplied to the spraying mechanism 22 of the dust collector 2 is adjusted to a state of about 0.4 MPaG and about 200 ° C., and spraying is started at appropriate time intervals. By these operations, non-condensable gas such as air in the drying chamber 11 and the tube 45 of the heat exchanger 4 existing at the start-up stage is discharged by the exhaust fan 922. The generated drain is discharged by the second drain pump 911.

Next, the steam compressor 6 and the steam blower 5 are started, the steam compressor 6 is controlled so that the pressure on the suction side becomes a predetermined pressure, and the steam blower 5 also has a pressure on the suction side as a predetermined pressure. Is controlled by. At this stage, since the drain has already evaporated from the heat exchanger 4, the steam is sucked into the steam blower 5. The steam blower 5 is operated so that the suction side of the steam blower 5 is about −0.05 MPaG, and the steam compressor 6 is operated so that the suction side of the steam compressor 6 is about 0.05 MPaG and about 111 ° C. To. Non-condensable gas in the steam compressor 6 and the steam blower 5 existing at the start-up stage, and in the paths before and after these are also discharged from appropriate discharge ports, and the discharge ports are closed after a certain period of time.

Next, the rotary valve 1121 of the discharge port 112 is activated, and for example, sewage sludge is charged as an object to be processed from the input port 111. The sludge comes into contact with the multi-tube heating tube 12 and the water is evaporated, and the evaporated water is collected from the exhaust port 114 through the dust collector 2 together with the carrier steam as recovered steam (heat exchange steam) at about 0.0 MPaG and about 112 ° C. It flows into the heat exchanger 4 in this state.

In addition to the starting method of charging the object to be processed from an empty state where there is no object to be processed in the drying chamber 11, it is also possible to start the process from a state in which the object to be processed is filled to some extent in the drying chamber 11 before starting. can. Further, the drying material may be filled in the drying chamber 11 before starting.

The object to be processed is dried while being moved from the input port 111 side to the discharge port 112 side, and is discharged as a dry substance from the discharge port 112 via the rotary valve 1121.

The charging of the object to be processed starts from a small amount of charging and is gradually increased so as to reach the set value of the charging amount. When the set value is reached, the start-up stage is completed and the steady operation stage is reached.

When the drying system D1 is operated in a stable state, high-temperature high-pressure steam of 0.5 MPaG and about 159 ° C. is obtained on the discharge side of the steam compressor 6, and this steam is supplied to the system header 7. The steam of the system header 7 will be used as the above-mentioned drying steam, carrier steam, or the like.

However, in reality, the material to be treated does not always have a constant physical property value, and the dispersed state of the material to be treated in the drying chamber 11 also fluctuates. Due to the influence of these fluctuations, the amount of steam of the high-temperature and high-pressure steam on the discharge side of the steam compressor 6 increases and decreases, and the pressure increases and decreases. When the pressure of the system header 7 becomes higher than the pressure set value SN2, excess steam is discharged from the regulating valve 73 to the atmosphere or the like.

The effect of this fluctuation also appears as a change in the degree of superheat of the steam sucked into the steam blower 5, and if the pressure of the system header 7 is higher than the pressure set value SN2, the degree of superheat is lower than the normal value. Is. For example, when the normal value of the degree of superheat, that is, the set value SN1 in the control unit PLC is 2 ° C, and the actual degree of superheat is 1 ° C, which is lower than this, the drain depends on the difference of 1 ° C. The opening degree of the control valve 35 will be narrowed down.

On the other hand, in the system header 7, the correction value Δt calculated based on the pressure difference between the pressure set value SN2 in the drying steam pressure gauge 71 and the actual pressure value higher than that is, for example. When the temperature is 0.2 ° C., 0.2 ° C. can be added to the set value SN1 to change the new set value SN1 to 2.2 ° C. The opening degree of the drain control valve 35 may be narrowed according to 1.2 ° C., which is the difference between the 2.2 ° C. and the above-mentioned actual superheat degree of 1 ° C.

Since the opening degree of the drain control valve 35 is narrowed, the amount of drain supplied to the heat exchanger 4 is reduced, and the steam sucked by the steam blower 5 is reduced, before the steam is discharged from the system header 7. In addition, the pressure of the system header 7 quickly converges to the pressure set value SN2.

Regarding the stop of the drying system D1, the charging of the object to be processed is first stopped, and the operation of supplying the drying steam and the carrier steam is continued until all the objects to be processed in the drying chamber 11 are dried, and then the operation is continued. Each device is stopped and valves are opened and closed in the reverse order of startup. In some cases, it is possible to stop each device in a state where all the objects to be processed in the drying chamber 11 are not dried, and to perform the next operation (start) with the objects to be processed left in the drying chamber 11.

Subsequently, the drying system of the second embodiment will be described. In the following description, the components having the same names as the components in the drying system of the first embodiment are designated by the same reference numerals as those used so far, and are different from the drying system of the first embodiment. Will be mainly explained.

FIG. 3 is a system diagram of the drying system of the second embodiment.

The drying system D2 of the second embodiment is also the same as the drying system D1 of the first embodiment, that is, the dryer 1, the dust collector 2, the drain tank 3, the heat exchanger 4, the steam blower 5, and the steam compressor. 6 and a system header 7 and the like are provided.

The drying system D2 of the second embodiment is different from the drying system D1 of the first embodiment in that a non-condensable gas can be supplied. That is, the carrier steam port 113 of the dryer 1 shown in FIG. 3 is connected so that the non-condensable gas can be supplied together with the carrier steam. The non-condensable gas is a gas that does not become liquid at least under the temperature and pressure in the closed system of the drying system D2 shown in FIG. 3, and specifically, outside air may be used or nitrogen gas. Etc. may be used. A non-condensable gas control valve 74 is provided in the non-condensable gas supply path connected to the carrier steam port 113 of the dryer 1, and the opening degree of the non-condensable gas control valve 74 is adjusted. Thereby, the supply amount of the non-condensable gas is adjusted. The drying system D2 of the second embodiment is also provided with a steam pressure gauge 71 for drying and a control unit PLC2. The control unit PLC2 receives information from the drying steam pressure gauge 71 and controls the opening degree of the non-condensable gas control valve 74.

Here, the supply control of the non-condensable gas in the drying system D2 of the second embodiment will be described.

For example, when the pressure of the system header 7 exceeds the pressure set value SN2, the non-condensable gas is supplied by the non-condensable gas control valve 74.

Specifically, information on the magnitude of the deviation between the pressure set value SN2 and the actual pressure value of the system header 7 is sent from the drying steam pressure gauge 71 to the control unit PLC2, and the calculation unit in the control unit PLC2. A PID control signal is sent to the non-condensable gas control valve 74 via the control unit, and the opening degree of the valve is controlled. Specifically, the control will be described. Within a certain pressure range in which the pressure of the system header 7 is determined by a pressure value lower than the pressure set value SN2 and a pressure value higher than the pressure set value SN2, the pressure set value SN2 The opening degree of the non-condensable gas control valve 74 may be controlled based on the deviation between the pressure value and the pressure value of the system header 7. In this case, if the pressure is lower than the pressure set value SN2 and less than the above pressure value, the non-condensable gas control valve 74 is fully closed and the non-condensable gas is not supplied. Further, when the pressure value of the system header 7 exceeds the predetermined speed from the pressure state lower than the pressure set value SN2 within a certain period of time, the pressure set value SN2 and the system Control regarding the supply of non-condensable gas is started based on the deviation from the pressure value of the header 7, and this control is performed until the pressure value of the system header 7 exceeds the pressure set value SN2 and then becomes less than the pressure set value SN2. It may be continued.

When the non-condensable gas is supplied, the non-condensable gas reaches the heat exchanger 4 in a state of being mixed with the recovered steam. In the heat exchanger 4, the recovery of the amount of heat of the recovered steam from the drying chamber 11 is rapidly reduced due to the presence of the non-condensable gas, and the heat exchange capacity in the heat exchanger 4 is also immediately reduced. Moreover, the heat exchange capacity can be reduced with a small amount of non-condensable gas. Therefore, the capacity control of the heat exchanger 4 can be efficiently performed with good reaction response. As a result, the amount of steam discharged from the heat exchanger 4 decreases, which reduces the pressure of the high-temperature high-pressure steam generated by the steam compressor 6, that is, the drying steam in the system header 7, and the pressure set value. It will converge to SN2. In the present embodiment, the non-condensable gas is supplied to the drying chamber 11 of the dryer 1, so that the non-condensable gas is contained in the steam recovered from the drying chamber 11, and the heat exchanger 4 is used. The steam passing through the inside of the tube 45 is mixed with a non-condensable gas. In the following description, the recovered steam is referred to as heat exchange steam regardless of the presence or absence of mixing of non-condensable gas. As described above, for example, if the pressure of the system header 7 is equal to or less than the pressure set value SN2, the supply of the non-condensable gas may be stopped. In this case, the inside of the tube 45 of the heat exchanger 4 may be stopped. In addition, a gas in which the non-condensable gas is not mixed with the heat exchange vapor will pass through.

According to the drying system D2 in the second embodiment, the pressure of the drying steam is reduced while the suction pressure in the steam blower 5 is kept constant and the compression ratio in the steam compressor 6 is also kept constant. The amount of heat of the drying steam supplied to the dryer 1 can be adjusted while maintaining the balance of the entire drying system D2. Further, since it is not necessary to increase the suction pressure in the steam blower 5 and the compression ratio in the steam compressor 6, the increase in power consumption is eliminated and energy saving operation can be realized.

As described above, the opening degree of the non-condensable gas control valve 74 is not controlled by PID control, but the pressure detection result of the system header 7 by the drying steam pressure gauge 71 is higher than the pressure set value SN2. Until then, the control signal for opening the non-condensable gas control valve 74 is not output, the non-condensable gas control valve 74 is maintained in a fully closed state, and when the detection result becomes the pressure set value SN2 or more, the non-condensable gas control valve 74 is not output. Control may be performed to fully open / fully close the non-condensable gas control valve 74 by outputting a control signal for opening the sex gas control valve 74.

According to the drying system D2 of the second embodiment, the heat recovery amount in the heat exchanger 4 is supplied to the heat exchanger 4 by adjusting the mixing amount of the non-condensable gas with the heat exchange steam. The amount can be adjusted separately from the adjustment, and as a result, the calorific value of the high-temperature and high-pressure steam reused as the drying steam can be adjusted in two stages, and the reaction response can be controlled better. ..

In the drying system D2 of the second embodiment, the non-condensable gas may be supplied to the path connecting the dust collector 2 and the heat exchanger 4, or may be supplied directly to the heat exchanger 4. There may be. That is, a non-condensable gas supply port may be provided in the path for sending the recovered steam to the heat exchanger 4, or a non-condensable gas supply port may be provided in a portion of the heat exchanger 4 through which the heat exchange steam passes. It may be provided. The non-condensable gas may be supplied to the drying chamber 11 of the dryer 1, the path connecting the dust collector 2 and the heat exchanger 4, and the heat exchanger 4 at three locations, respectively. Of the locations, the heat may be supplied only to the path connecting the drying chamber 11 of the dryer 1, the dust collector 2 and the heat exchanger 4, or the path connecting the dust collector 2 and the heat exchanger 4 and the heat exchanger 4. It may be supplied only to the drying chamber 11 of the dryer 1 and the heat exchanger 4. Further, it may be supplied only to the path connecting the dust collector 2 and the heat exchanger 4, or only to the heat exchanger 4.

Further, in the drying system D2 of the second embodiment, the opening degree of the non-condensable gas control valve 74 is set by the control unit PLC2, but the result displayed on the drying steam pressure gauge 71 is manually checked. The opening degree of the non-condensable gas control valve 74 may be operated.

Alternatively, the non-condensable gas control valve 74 may be a self-powered automatic expansion valve in which a temperature sensitive portion for simultaneously detecting pressure and temperature is provided in the system header 7.

The combination of the non-condensable gas control valve 74 and the control unit PLC2 corresponds to an example of the second adjusting unit, and when the non-condensable gas control valve 74 is manually opened and closed, the non-condensable gas control valve 74 is not condensed. The control valve 74 for sex gas corresponds to an example of the second adjusting unit. The above-mentioned automatic expansion valve also corresponds to an example of the second adjusting unit.

Most of the operating methods and drying methods of the apparatus relating to the drying system D2 of the present invention overlap with those of the drying system D1. The difference is that the opening control of the non-condensable gas control valve 74, which is the second adjusting unit described above, functions together with the control by the first adjusting unit.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.

For example, in both the drying system D1 of the first embodiment and the drying system D2 of the second embodiment, the dryer 1 is a continuous conduction heat transfer type dryer having a multi-tube heating tube 12. However, it may be a continuous conduction heat transfer type dryer such as a so-called paddle dryer in which the stirring part and the rotating shaft part form an indirect heating part.

Further, in both the drying system D1 of the first embodiment and the drying system D2 of the second embodiment, the heat exchanger 4 was a vertical type (vertical installation), but a horizontal type (horizontal installation). It may be. However, in the embodiment of the vertical heat exchanger 4, the condensed water generated by the heat exchange between the recovered steam and the drain flows down in the vertical tube 45, so that the condensed water is unevenly distributed near the boundary film on the inner surface of the tube 45. The condensable gas is rapidly discharged to the outside of the tube 45 together with the flow of the condensed water. Therefore, the non-condensable gas is unlikely to remain in the tube 45, and the change in the supply amount of the non-condensable gas rapidly appears in the heat exchange, which is more excellent in terms of reaction responsiveness.

Further, in both the drying system D1 of the first embodiment and the drying system D2 of the second embodiment, the heat exchanger 4 has been described as a dry heat exchanger, but the drainage is contained in the heat exchanger 4. In order to provide a liquid pool, the drain outlet may be provided at a height higher than that of the lower can plate 43 so that the liquid level is required, and a part of the tube 45 may be immersed in the drain. As a result, the drain can be evaporated from the tube 45 in the range of being immersed in the drain. In the field of heat exchangers, a heat exchanger in which a liquid (drain in the present invention) is stored and used in the heat exchanger may be referred to as a full-liquid heat exchanger.

In the above description, the case where a dry product having a small amount of evaporation component is obtained from a solid object to be treated containing a large amount of evaporation component such as water has been described. It is also applicable to the case where the components are evaporated to obtain a concentrated liquid, in which case the drying systems D1 and D2 become a concentration system, the dryer 1 becomes a concentrator, and the drying chamber 11 concentrates. Become a room. Further, the steam for drying becomes steam for concentration, and the dried product becomes a concentrate.

Even if the constituent requirements are included only in the description of each of the above-described embodiments, the constituent requirements may be applied to other embodiments.

D1, D2 Drying system 1 Dryer 11 Drying chamber 12 Multi-tube heating tube 2 Dust collector 3 Drain tank 35 Drain water control valve 4 Heat exchanger 41 Shell 45 Tube 46 Overheat meter 5 Steam blower 6 Steam compressor 7 System header 8 Overheater 71 Drying steam pressure gauge 72 Auxiliary steam control valve 74 Non-condensable gas control valve PLC control unit

Claims (7)

It is equipped with a heat transfer member that is placed in the drying / concentrating chamber and allows steam for drying / concentrating to pass through the inside of the heat transfer member. In a drying / concentrating system provided with a drying / concentrating machine that transfers the heat of the steam for drying / concentrating to the object to be processed to dry / concentrate the object to be processed.
The steam recovered from the drying / concentrating chamber and the drain recovered from the heat transfer member are supplied, the steam is used as heat exchange steam, and the drain is evaporated using the heat amount of the heat exchange steam to steam. With a heat exchanger that discharges
A compressor that compresses the steam discharged from the heat exchanger to obtain high-temperature and high-pressure steam that is reused as the drying / concentrating steam.
Drying and concentration system characterized by comprising, depending on the state of the discharged steam, and a first adjusting unit capable of adjusting the supply amount of the drain supplied to the heat exchanger from the heat exchanger. The drying / concentrating system according to claim 1, wherein the first adjusting unit can adjust the supply amount according to the degree of superheat of the steam discharged from the heat exchanger. It is equipped with an output unit that outputs information according to the state of the high-temperature and high-pressure steam obtained by the compressor.
The first adjusting unit is characterized in that the supply amount can be adjusted based on the degree of superheat of the steam discharged from the heat exchanger and the information from the output unit. Drying and concentrating system. The heat exchanger exchanges heat between a gas in which a non-condensable gas is mixed with the heat exchange steam and a supplied drain to evaporate the drain.
An output unit that outputs information according to the state of the high-temperature and high-pressure steam obtained by the compressor, and
Any of claims 1 to 3, further comprising a second adjusting unit that can adjust the mixing amount of the non-condensable gas with the heat exchange steam based on the information from the output unit. The drying / concentrating system according to item 1. The drying / concentrating system according to claim 4, wherein the drying / concentrating chamber is provided with a supply port for the non-condensable gas. The drying / concentrating system according to claim 4 or 5, wherein the non-condensable gas supply port is provided in a path for sending the steam recovered from the drying / concentrating chamber to the heat exchanger. The drying / concentrating system according to any one of claims 4 to 6, wherein the heat exchanger is provided with a supply port for the non-condensable gas.

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