CN218393011U

CN218393011U - NMP synthesis rear end tail gas absorbing device

Info

Publication number: CN218393011U
Application number: CN202222186462.XU
Authority: CN
Inventors: 陶斯强; 李程明; 林云; 连超; 刘晓军; 刘龙波
Original assignee: Anhui Shengjie New Energy Technology Co ltd
Current assignee: Anhui Shengjie New Energy Technology Co ltd
Priority date: 2022-08-19
Filing date: 2022-08-19
Publication date: 2023-01-31
Anticipated expiration: 2032-08-19

Abstract

The utility model discloses a synthetic rear end tail gas absorbing device of NMP, including absorption tower group and circulating pump group, the sealed intercommunication of the output of absorption tower group bottom and circulating pump group's input, the sealed intercommunication of circulating pump group's output has the reposition of redundant personnel nest of tubes, the sealed intercommunication of the left input of absorption tower group has the colating assembly, the sealed intercommunication of the other end of colating assembly has the group of admitting air, the sealed intercommunication of the input on absorption tower group right side has the raceway. The utility model overcomes prior art's is not enough, reasonable in design, compact structure, the inner structure of colating subassembly is simple, conveniently carries out the solid particle filtration processing when using to conveniently carry out its inside subassembly and change the processing, at the in-process that whole device used, the circulating pump group that connects in parallel and set up can be in the running state still at primary circulating pump or secondary circulating pump stall, has higher social use value and application prospect.

Description

NMP synthesis rear end tail gas absorbing device

Technical Field

The utility model relates to a NMP synthetic processing technology field especially relates to a synthetic rear end tail gas absorbing device of NMP.

Background

NMP is a colorless and slightly ammoniacal transparent liquid as a general solvent or an intermediate in chemical synthesis processes, and is usually synthesized from γ -butyrolactone and methylamine; in the process of tail gas absorption at the synthesis rear end of the modern product, the absorption reaction tower with the circulating absorption equipment is a single kinetic energy output pipe network, the defect that the whole equipment cannot normally operate due to the fact that kinetic energy output stops in the circulation process is easily caused, and a certain amount of magazines can be suspended in the tail gas, so that the blockage in the pipeline is easily caused.

The publication number is 201820388663.9, which discloses a tail gas absorption tower, comprising a tower body, a tail gas inlet pipe and a reaction liquid inlet pipe, wherein the upper part of the tower body is provided with a tail gas outlet pipe, the lower part of the tower body is provided with a reaction liquid outlet pipe, the reaction liquid outlet pipe is provided with a reaction liquid circulating pipe, one end of the reaction liquid circulating pipe is connected with the reaction liquid outlet pipe, the other end of the reaction liquid circulating pipe is communicated with the upper part of the tower body, the inside of the tower body is provided with a spraying device connected with the reaction liquid circulating pipe, the tower body is also provided with a TIR unit, a LIRC unit and a PH meter, however, when the circulation treatment is carried out on the pipe network, solid particles in the tail gas are accumulated in the pipe network, and the solid particles are adhered to the inner wall of the pipe, so that the circulation inside the pipe is caused by excessive accumulation of the solid particles, and the circulation equipment is a single passage, and the whole equipment can not normally run due to blockage, therefore, a device capable of carrying out front-section coarse filtration on the circulation absorption pipe network pipeline is provided, the tail gas can be filtered before entering the reaction tower, and the tail gas can be prevented from being accumulated in the inside of the pipe or on the inner wall of the reaction tower.

Therefore, the inventor provides a tail gas absorption device after NMP synthesis, which is developed based on the experience of design development and actual manufacturing in the related industry for many years, and is improved by research aiming at the existing structure and deficiency, so as to achieve the purpose of more practical value.

SUMMERY OF THE UTILITY MODEL

In order to solve the tail gas absorption processing in-process that mentions among the above-mentioned background art, the circulation of tail gas causes the solid particle of suspension in the tail gas to pile up among the pipe network pipeline and single pipeline blocks up and causes the unable moving problem of whole equipment, the utility model provides a synthetic rear end tail gas absorbing device of NMP.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the utility model provides a synthetic rear end tail gas absorbing device of NMP, includes absorption tower group and circulating pump group, the sealed intercommunication of the output of absorption tower group bottom and circulating pump group's input, the sealed intercommunication of output of circulating pump group has reposition of redundant personnel nest of tubes, the sealed intercommunication of the left input of absorption tower group has the coarse filter subassembly, the sealed intercommunication of the other end of coarse filter subassembly has the group of admitting air, the sealed intercommunication of the input on absorption tower group right side has the raceway, the sealed intercommunication of the output at absorption tower group right side top has the blow-down pipe, the middle-end intercommunication cover of blow-down pipe surface is equipped with the detection pipe network.

Preferably, the absorption tower set comprises a first-stage absorption tower, a second-stage absorption tower and a third-stage absorption tower, the top output end of the first-stage absorption tower is hermetically communicated with the top input end of the side face of the second-stage absorption tower, the top output end of the second-stage absorption tower is hermetically communicated with the top input end of the side face of the third-stage absorption tower, the top output end of the third-stage absorption tower is hermetically communicated with the bottom end of the vent pipe, the input end of the top portion of the right side face of the first-stage absorption tower is hermetically communicated with the output end of the diversion pipe set, the input end of the top portion of the right side face of the second-stage absorption tower is hermetically communicated with the output end of the diversion pipe set, the input end of the left bottom of the first-stage absorption tower is hermetically communicated with the input end of the diversion pipe set, the input end of the left bottom of the second-stage absorption tower is hermetically communicated with the input end of the diversion pipe set, the input end of the left bottom of the third-stage absorption tower is hermetically communicated with the input end of the diversion pipe set, the bottom of the first-stage absorption tower is hermetically communicated with the input end of the circulation pump set, the bottom of the second-stage absorption tower is hermetically communicated with the input end of the circulation pump set, and the bottom of the third-stage absorption tower is hermetically communicated with the input end of the circulation pump set.

Preferably, the circulation pump group comprises a main circulation pump and a secondary circulation pump, wherein the input end of the main circulation pump is communicated with the input end of the main circulation pump in parallel, the input end of the main circulation pump and the input end of the secondary circulation pump are communicated with the bottom output end of the absorption tower group in parallel in a sealing mode, the output end of the secondary circulation pump is communicated with the output end of the main circulation pump in parallel in a sealing mode, and the output end of the secondary circulation pump and the top end of the output end of the main circulation pump in parallel in a sealing mode are communicated with the bottom end of the diversion pipe group.

Preferably, the flow distribution pipe group comprises a first-stage flow distribution pipe, a second-stage flow distribution pipe and a third-stage flow distribution pipe, the bottom ends of the first-stage flow distribution pipe, the bottom ends of the second-stage flow distribution pipe and the bottom ends of the third-stage flow distribution pipe are respectively communicated with a circulating pump group in a sealing mode, the number of the circulating pump groups is three, and pipelines of the flow distribution pipe group are communicated with external pipelines of the absorption tower group in a sealing mode.

Preferably, the colating subassembly is including filtering the box, the top surface bolt cover of filtering the box has been connect the apron, both ends all are equipped with the connecting pipe around filtering the box, both ends all are equipped with fixed the knot around the filtering the box left and right sides face, the inside of fixed knot all is equipped with the support bar, the outside end of support bar is equipped with the fastener, the perforation has been seted up to the lateral surface of support bar, the locking hole has been seted up to the lateral surface of fixed knot.

Preferably, the group of admitting air includes first intake pipe and second intake pipe, the quantity of coarse filter subassembly is two, two coarse filter subassemblies respectively with the right side tip of first intake pipe and the sealed intercommunication of the right side tip of second intake pipe, the left top surface of first intake pipe is equipped with air intake branch, air intake branch's quantity is three.

Preferably, the detection pipe network includes gas-supply pipe, first blast gate, tail gas fan, detection instrument and second blast gate, the pipeline of gas-supply pipe is located to first blast gate, tail gas fan, detection instrument and second blast gate series connection cover in proper order, the top output of gas-supply pipe and the bottom input of gas-supply pipe are established in the sealed cover in top and the bottom at blow-down pipe surface left side middle part respectively, the middle part cover of blow-down pipe is equipped with main blast gate.

Compared with the prior art, the beneficial effects of the utility model are that:

1. at first through the setting of coarse filtration subassembly, utilize the cooperation between the inner assembly of coarse filtration subassembly, can carry out the coarse filtration processing of anterior segment for the leading-in inside tail gas of one-level absorption tower of first intake pipe and second intake pipe for suspended solid-state particle carries out filtration processing in the leading-in tail gas of first intake pipe and second intake pipe, and can let the coarse filtration subassembly provide for being connected between first intake pipe and second intake pipe and the one-level absorption tower and bind fixed effect, avoid the interface to appear becoming flexible.

2. Secondly, through the setting of circulating pump group, utilize the parallelly connected expert between main circulating pump and the secondary circulating pump to according to the connected mode of one-level absorption tower, second grade absorption tower and tertiary absorption tower, can carry out the components of a whole that can function independently control to main circulating pump and secondary circulating pump that first grade absorption tower, second grade absorption tower and tertiary absorption tower bottom communicate, avoid appearing single pump body and appear damaging and lead to the unable operating state appearance of whole device.

To sum up, the utility model overcomes prior art's is not enough, reasonable in design, compact structure, the inner structure of colating subassembly is simple, conveniently carries out the solid particle filtration processing when using to conveniently carry out its inside subassembly and change the processing, at the in-process that whole device used, the circulating pump group of parallelly connected setting can let whole state still be in running state when primary circulating pump or secondary circulating pump stall, has higher social use value and application prospect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the coarse filter assembly of the present invention;

FIG. 3 is an enlarged view of a portion A of FIG. 1;

fig. 4 is an enlarged view of a portion B in fig. 1.

In the figure: 1. an absorption tower set; 101. a first-stage absorption tower; 102. a secondary absorption tower; 103. a third stage absorption tower; 2. a circulating pump group; 21. a primary circulation pump; 22. a secondary circulation pump; 3. a shunt tube group; 31. a first-stage shunt pipe; 32. a secondary shunt tube; 33. a third stage shunt tube; 4. a coarse filtration component; 41. a filter box; 411. a connecting pipe; 42. a cover plate; 43. a fixing buckle; 44. a supporting strip; 441. perforating; 45. a fastener; 5. an air intake group; 51. a first intake pipe; 511. an intake branch pipe; 52. a second intake pipe; 6. a water delivery pipe; 7. an emptying pipe; 71. a main air valve; 8. detecting a pipe network; 81. a gas delivery pipe; 82. a first air valve; 83. a tail gas fan; 84. detecting a meter; 85. and a second air valve.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Example 1

Referring to fig. 1-4, synthetic rear end tail gas absorption device of NMP, including absorption tower 1 and circulating pump group 2, the sealed intercommunication of the output of absorption tower 1 bottom and the input of circulating pump group 2, the sealed intercommunication of the output of circulating pump group 2 has reposition of redundant personnel nest of tubes 3, the sealed intercommunication of the left input of absorption tower 1 has coarse filtration subassembly 4, the sealed intercommunication of the other end of coarse filtration subassembly 4 has group 5 of admitting air, the sealed intercommunication of the input on absorption tower 1 right side has raceway 6, the sealed intercommunication of the output at absorption tower 1 right side top has blow-down pipe 7, the middle-end intercommunication cover of blow-down pipe 7 surface is equipped with detection pipe network 8.

The absorption tower group 1 comprises a first-stage absorption tower 101, a second-stage absorption tower 102 and a third-stage absorption tower 103, the top output end of the first-stage absorption tower 101 is hermetically communicated with the side top input end of the second-stage absorption tower 102, the top output end of the second-stage absorption tower 102 is hermetically communicated with the side top input end of the third-stage absorption tower 103, the top output end of the third-stage absorption tower 103 is hermetically communicated with the bottom end of an air vent pipe 7, the input end of the right side top of the first-stage absorption tower 101 is hermetically communicated with the output end of a shunt pipe group 3, the input end of the right side top of the second-stage absorption tower 102 is hermetically communicated with the output end of the shunt pipe group 3, the input end of the right side top of the third-stage absorption tower 103 is hermetically communicated with the input end of the shunt pipe group 3, the input end of the left side bottom of the first-stage absorption tower 101 is hermetically communicated with the input end of the circulation pump group 2, the bottom output end of the second-stage absorption tower 102 is hermetically communicated with the input end of the circulation pump group 2, the sealed absorption tower 103 is communicated with the input end of the circulation pump group 103, the absorption tower 102, the absorption tower can utilize the kinetic energy of the circulation tower 1 and the absorption tower 102 and the circulation tower to process tail gas, and the tail gas, and tail gas.

Specifically, the circulating pump group 2 includes primary circulation pump 21 and secondary circulation pump 22, the input of primary circulation pump 21 and the parallelly connected intercommunication of primary circulation pump 21's input, the input of primary circulation pump 21 and the parallelly connected pipeline of secondary circulation pump 22's input and the sealed intercommunication of bottom output of absorption tower group 1, the output of secondary circulation pump 22 and the parallelly connected intercommunication of primary circulation pump 21's output, the output of secondary circulation pump 22 and primary circulation pump 21's the parallelly connected pipeline's of output top and the sealed intercommunication of the bottom of reposition of redundant personnel nest of tubes 3, the setting of circulating pump group 2 can provide parallelly connected kinetic energy output for the integrated device, avoid single kinetic energy output to stop to let whole device carry out the condition of lasting operation appear, can carry out the control of opening and shutting of pipeline through the valve body of intercommunication between the pipeline and handle.

Specifically, the shunting pipe group 3 comprises a first-stage shunting pipe 31, a second-stage shunting pipe 32 and a third-stage shunting pipe 33, the bottom ends of the first-stage shunting pipe 31, the second-stage shunting pipe 32 and the third-stage shunting pipe 33 are respectively communicated with a circulating pump group 2 in a sealing mode, the number of the circulating pump groups 2 is three, the pipelines of the shunting pipe group 3 are communicated with the external pipelines of the absorption tower group 1 in a sealing mode, the arrangement of the shunting pipe group 3 can aim at the circulating communication effect between the first-stage absorption tower 101 and the second-stage absorption tower 102 and the third-stage absorption tower 103, the communication between different pipelines is processed, and the first-stage absorption tower 101, the second-stage absorption tower 102 and the third-stage absorption tower 103 can be communicated to form a circulating absorption channel.

Specifically, coarse filter component 4 includes filter box 41, the top surface bolt of filter box 41 has cup jointed apron 42, the equal thread sealing cover in both ends is equipped with connecting pipe 411 around filter box 41, both ends all are equipped with fixed knot 43 around the filter box 41 left and right sides face, the inside of fixed knot 43 all is equipped with support bar 44, the outside end of support bar 44 is equipped with fastener 45, perforation 441 has been seted up to support bar 44's lateral surface, the locking hole has been seted up to fixed knot 43's lateral surface, fastener 45 can close the surface of detaining at the external pipeline of needs through the bolt snap-on, can let the inside tail gas of first intake pipe 51 and the leading-in one-level absorption tower 101 of second intake pipe 52 carry out the coarse filtration processing of front end through setting up of coarse filter component 4, let most solid particle that contains in the tail gas leave in the inside filter core that sets up of filter box 41, avoid appearing the too much condition that causes to pile up the jam.

Specifically, air inlet group 5 includes first intake pipe 51 and second intake pipe 52, and the quantity of rough filter subassembly 4 is two, and two rough filter subassemblies 4 are sealed with the right side tip of first intake pipe 51 and the right side tip of second intake pipe 52 respectively and are communicated, and the left top surface of first intake pipe 51 is equipped with air inlet branch pipe 511, and air inlet branch pipe 511's quantity is three, through air inlet group 5's setting, can carry out the intercommunication processing of pipeline for the tail gas that retort body and the intermediate tank body and the raw materials jar body released respectively.

Specifically, detection pipe network 8 includes air supply pipe 81, first blast gate 82, tail gas fan 83, instrumentation 84 and second blast gate 85 are established ties in proper order and are located the pipeline of air supply pipe 81, the top output of air supply pipe 81 and the bottom input of air supply pipe 81 are established in the top and the bottom seal cover at the middle part of blow-down pipe 7 surface left side respectively, the middle part cover of blow-down pipe 7 is equipped with main blast gate 71, the setting of detection pipe network 8 can detect before the tail gas after handling needs discharge, wait to detect after up to standard, alright in order to open main blast gate 71 and carry out discharge treatment.

The working principle is as follows: the utility model discloses in, add between the intercommunication passageway between first intake pipe 51 and second intake pipe 52 and the one-level absorption tower 101 and establish and cup jointed coarse filtration subassembly 4, let the inside air of the leading-in one-level absorption tower 101 of first intake pipe 51 and second intake pipe 52 carry out filtration treatment through the inside of coarse filtration subassembly 4, let solid particle among the tail gas can filter, avoid the inside of the leading-in one-level absorption tower 101 of a large amount of solid particle, make the inside a large amount of solid particle of remaining of subassembly of absorption tower group 1, be equipment moving time primary circulating pump 21 and secondary circulating pump 22 be in parallelly connected processing, opening and closing between primary circulating pump 21 and the secondary circulating pump 22 can go on in step, also can singly go on, the control action between output channel's control valve between utilizing primary circulating pump 21 and the secondary circulating pump 22 carries out and the reposition of redundant personnel nest of redundant personnel 3, then after the tail gas treatment, can detect the tail gas after handling by detecting pipe network 8, after detecting and reaching standard, alright in order to open main blast valve 71, let the tail gas after handling can through the discharge between 7.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "disposed," "mounted," "connected," "secured," and the like are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally formed; they may be mechanically coupled, directly coupled, or indirectly coupled through intervening agents, both internally and/or in any other manner known to those skilled in the art. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

The utility model discloses a control mode comes automatic control through the controller, and the control circuit of controller can realize through the simple programming of technical staff in this field, and the supply also belongs to the common general knowledge in this field, and the utility model discloses mainly used protects mechanical device, so the utility model discloses no longer explain control mode and circuit connection in detail.

The above, only be the embodiment of the preferred of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art is in the technical scope of the present invention, according to the technical solution of the present invention and the utility model, which are designed to be replaced or changed equally, all should be covered within the protection scope of the present invention.

Claims

1. The utility model provides a synthetic rear end tail gas absorbing device of NMP, includes absorption tower group (1) and circulating pump group (2), its characterized in that: the output of absorption tower group (1) bottom and the sealed intercommunication of the input of circulating pump group (2), the sealed intercommunication of the output of circulating pump group (2) has reposition of redundant personnel nest of tubes (3), the sealed intercommunication of the left input of absorption tower group (1) has coarse filter subassembly (4), the sealed intercommunication of the other end of coarse filter subassembly (4) has air intake group (5), the sealed intercommunication of the input on absorption tower group (1) right side has raceway (6), the sealed intercommunication of the output at absorption tower group (1) right side top has blow-down pipe (7), the middle-end intercommunication cover of blow-down pipe (7) surface is equipped with detection pipe network (8).

2. A NMP synthesis tail gas absorber according to claim 1, wherein: the absorption tower set (1) comprises a primary absorption tower (101), a secondary absorption tower (102) and a tertiary absorption tower (103), the top output end of the primary absorption tower (101) is hermetically communicated with the side top input end of the secondary absorption tower (102), the top output end of the secondary absorption tower (102) is hermetically communicated with the side top input end of the tertiary absorption tower (103), the top output end of the tertiary absorption tower (103) is hermetically communicated with the bottom end of a vent pipe (7), the input end of the top of the right side of the primary absorption tower (101) is hermetically communicated with the output end of a shunt pipe set (3), the input end of the top of the right side of the secondary absorption tower (102) is hermetically communicated with the output end of the shunt pipe set (3), the input end of the top of the right side of the tertiary absorption tower (103) is hermetically communicated with the left side output end of a water pipe (6), the input end of the bottom of the left side of the primary absorption tower (101) is hermetically communicated with the input end of the shunt pipe set (3), the input end of the bottom of the left side of the secondary absorption tower (102) is hermetically communicated with the input end of the shunt pipe set (3), the input end of a tertiary absorption tower (103) is hermetically communicated with the input end of the primary absorption tower (2), and the input end of the circulating tower (102) is hermetically communicated with the input end of the circulating tower (2), and the bottom output end of the three-stage absorption tower (103) is hermetically communicated with the input end of the circulating pump group (2).

3. The NMP synthesis tail gas absorber according to claim 1, wherein: the circulating pump group (2) comprises a main-stage circulating pump (21) and a secondary circulating pump (22), the input end of the main-stage circulating pump (21) is communicated with the input end of the main-stage circulating pump (21) in parallel, the input end of the main-stage circulating pump (21) and the input end of the secondary circulating pump (22) are communicated with the bottom output end of the absorption tower group (1) in a sealing mode, the output end of the secondary circulating pump (22) is communicated with the output end of the main-stage circulating pump (21) in parallel, and the top end of the output end of the secondary circulating pump (22) and the top end of the output end of the main-stage circulating pump (21) in parallel are communicated with the bottom end of the shunt pipe group (3) in a sealing mode.

4. A NMP synthesis tail gas absorber according to claim 1, wherein: the utility model discloses a circulating pump group, including the absorption tower group, the reposition of redundant personnel nest of tubes (3) is including one-level shunt tubes (31), second grade shunt tubes (32) and tertiary shunt tubes (33), the sealed intercommunication in bottom of one-level shunt tubes (31), second grade shunt tubes (32) and tertiary shunt tubes (33) has circulating pump group (2) respectively, the quantity of circulating pump group (2) is three, the pipeline of reposition of redundant personnel nest of tubes (3) and the sealed intercommunication of external pipeline of absorption tower group (1).

5. A NMP synthesis tail gas absorber according to claim 1, wherein: coarse filter subassembly (4) is including straining box (41), the top surface bolt housing of straining box (41) has apron (42), both ends all overlap and are equipped with connecting pipe (411) around straining box (41), both ends all are equipped with fixed knot (43) around straining box (41) the left and right sides face, the inside of fixed knot (43) all is equipped with support bar (44), the outside end of support bar (44) is equipped with fastener (45), perforation (441) have been seted up to the lateral surface of support bar (44), the locking hole has been seted up to the lateral surface of fixed knot (43).

6. The NMP synthesis tail gas absorber according to claim 1, wherein: the group (5) of admitting air includes first intake pipe (51) and second intake pipe (52), the quantity of coarse filter subassembly (4) is two, two coarse filter subassemblies (4) respectively with the right side tip of first intake pipe (51) and the sealed intercommunication of right side tip of second intake pipe (52), the left top surface of first intake pipe (51) is equipped with air intake branch (511), the quantity of air intake branch (511) is three.

7. The NMP synthesis tail gas absorber according to claim 1, wherein: detect pipe network (8) including gas-supply pipe (81), first blast gate (82), tail gas fan (83), instrumentation (84) and second blast gate (85), the pipeline of gas-supply pipe (81) is located to first blast gate (82), tail gas fan (83), instrumentation (84) and second blast gate (85) series connection cover in proper order, the top output of gas-supply pipe (81) and the bottom input of gas-supply pipe (81) are established respectively in the top and the bottom seal cover at blow-down pipe (7) surface left side middle part, the middle part cover of blow-down pipe (7) is equipped with main blast gate (71).